Merge pull request #14523 from ziglang/zon

introduce Zig Object Notation and use it for the build manifest file (build.zig.zon)

CMakeLists.txt

@@ -513,7 +513,7 @@ set(ZIG_STAGE2_SOURCES
     "${CMAKE_SOURCE_DIR}/lib/std/zig/Ast.zig"
     "${CMAKE_SOURCE_DIR}/lib/std/zig/CrossTarget.zig"
     "${CMAKE_SOURCE_DIR}/lib/std/zig/c_builtins.zig"
-    "${CMAKE_SOURCE_DIR}/lib/std/zig/parse.zig"
+    "${CMAKE_SOURCE_DIR}/lib/std/zig/Parse.zig"
     "${CMAKE_SOURCE_DIR}/lib/std/zig/render.zig"
     "${CMAKE_SOURCE_DIR}/lib/std/zig/string_literal.zig"
     "${CMAKE_SOURCE_DIR}/lib/std/zig/system.zig"

lib/std/Build.zig

@@ -1496,8 +1496,8 @@ pub fn dependency(b: *Build, name: []const u8, args: anytype) *Dependency {
         }
     }
 
-    const full_path = b.pathFromRoot("build.zig.ini");
-    std.debug.print("no dependency named '{s}' in '{s}'\n", .{ name, full_path });
+    const full_path = b.pathFromRoot("build.zig.zon");
+    std.debug.print("no dependency named '{s}' in '{s}'. All packages used in build.zig must be declared in this file.\n", .{ name, full_path });
     std.process.exit(1);
 }
 

lib/std/Build/OptionsStep.zig

@@ -367,5 +367,5 @@ test "OptionsStep" {
         \\
     , options.contents.items);
 
-    _ = try std.zig.parse(arena.allocator(), try options.contents.toOwnedSliceSentinel(0));
+    _ = try std.zig.Ast.parse(arena.allocator(), try options.contents.toOwnedSliceSentinel(0), .zig);
 }

lib/std/array_hash_map.zig

@@ -1145,7 +1145,8 @@ pub fn ArrayHashMapUnmanaged(
         }
 
         /// Create a copy of the hash map which can be modified separately.
-        /// The copy uses the same context and allocator as this instance.
+        /// The copy uses the same context as this instance, but is allocated
+        /// with the provided allocator.
         pub fn clone(self: Self, allocator: Allocator) !Self {
             if (@sizeOf(ByIndexContext) != 0)
                 @compileError("Cannot infer context " ++ @typeName(Context) ++ ", call cloneContext instead.");

lib/std/zig.zig

@@ -8,7 +8,6 @@ pub const Tokenizer = tokenizer.Tokenizer;
 pub const fmtId = fmt.fmtId;
 pub const fmtEscapes = fmt.fmtEscapes;
 pub const isValidId = fmt.isValidId;
-pub const parse = @import("zig/parse.zig").parse;
 pub const string_literal = @import("zig/string_literal.zig");
 pub const number_literal = @import("zig/number_literal.zig");
 pub const primitives = @import("zig/primitives.zig");

lib/std/zig/Ast.zig

@@ -1,4 +1,8 @@
 //! Abstract Syntax Tree for Zig source code.
+//! For Zig syntax, the root node is at nodes[0] and contains the list of
+//! sub-nodes.
+//! For Zon syntax, the root node is at nodes[0] and contains lhs as the node
+//! index of the main expression.
 
 /// Reference to externally-owned data.
 source: [:0]const u8,
@@ -11,13 +15,6 @@ extra_data: []Node.Index,
 
 errors: []const Error,
 
-const std = @import("../std.zig");
-const assert = std.debug.assert;
-const testing = std.testing;
-const mem = std.mem;
-const Token = std.zig.Token;
-const Ast = @This();
-
 pub const TokenIndex = u32;
 pub const ByteOffset = u32;
 
@@ -34,7 +31,7 @@ pub const Location = struct {
     line_end: usize,
 };
 
-pub fn deinit(tree: *Ast, gpa: mem.Allocator) void {
+pub fn deinit(tree: *Ast, gpa: Allocator) void {
     tree.tokens.deinit(gpa);
     tree.nodes.deinit(gpa);
     gpa.free(tree.extra_data);
@@ -48,11 +45,69 @@ pub const RenderError = error{
     OutOfMemory,
 };
 
+pub const Mode = enum { zig, zon };
+
+/// Result should be freed with tree.deinit() when there are
+/// no more references to any of the tokens or nodes.
+pub fn parse(gpa: Allocator, source: [:0]const u8, mode: Mode) Allocator.Error!Ast {
+    var tokens = Ast.TokenList{};
+    defer tokens.deinit(gpa);
+
+    // Empirically, the zig std lib has an 8:1 ratio of source bytes to token count.
+    const estimated_token_count = source.len / 8;
+    try tokens.ensureTotalCapacity(gpa, estimated_token_count);
+
+    var tokenizer = std.zig.Tokenizer.init(source);
+    while (true) {
+        const token = tokenizer.next();
+        try tokens.append(gpa, .{
+            .tag = token.tag,
+            .start = @intCast(u32, token.loc.start),
+        });
+        if (token.tag == .eof) break;
+    }
+
+    var parser: Parse = .{
+        .source = source,
+        .gpa = gpa,
+        .token_tags = tokens.items(.tag),
+        .token_starts = tokens.items(.start),
+        .errors = .{},
+        .nodes = .{},
+        .extra_data = .{},
+        .scratch = .{},
+        .tok_i = 0,
+    };
+    defer parser.errors.deinit(gpa);
+    defer parser.nodes.deinit(gpa);
+    defer parser.extra_data.deinit(gpa);
+    defer parser.scratch.deinit(gpa);
+
+    // Empirically, Zig source code has a 2:1 ratio of tokens to AST nodes.
+    // Make sure at least 1 so we can use appendAssumeCapacity on the root node below.
+    const estimated_node_count = (tokens.len + 2) / 2;
+    try parser.nodes.ensureTotalCapacity(gpa, estimated_node_count);
+
+    switch (mode) {
+        .zig => try parser.parseRoot(),
+        .zon => try parser.parseZon(),
+    }
+
+    // TODO experiment with compacting the MultiArrayList slices here
+    return Ast{
+        .source = source,
+        .tokens = tokens.toOwnedSlice(),
+        .nodes = parser.nodes.toOwnedSlice(),
+        .extra_data = try parser.extra_data.toOwnedSlice(gpa),
+        .errors = try parser.errors.toOwnedSlice(gpa),
+    };
+}
+
 /// `gpa` is used for allocating the resulting formatted source code, as well as
 /// for allocating extra stack memory if needed, because this function utilizes recursion.
 /// Note: that's not actually true yet, see https://github.com/ziglang/zig/issues/1006.
 /// Caller owns the returned slice of bytes, allocated with `gpa`.
-pub fn render(tree: Ast, gpa: mem.Allocator) RenderError![]u8 {
+pub fn render(tree: Ast, gpa: Allocator) RenderError![]u8 {
     var buffer = std.ArrayList(u8).init(gpa);
     defer buffer.deinit();
 
@@ -3347,3 +3402,12 @@ pub const Node = struct {
         rparen: TokenIndex,
     };
 };
+
+const std = @import("../std.zig");
+const assert = std.debug.assert;
+const testing = std.testing;
+const mem = std.mem;
+const Token = std.zig.Token;
+const Ast = @This();
+const Allocator = std.mem.Allocator;
+const Parse = @import("Parse.zig");

lib/std/zig/Parse.zig

@@ -0,0 +1,3825 @@
+//! Represents in-progress parsing, will be converted to an Ast after completion.
+
+pub const Error = error{ParseError} || Allocator.Error;
+
+gpa: Allocator,
+source: []const u8,
+token_tags: []const Token.Tag,
+token_starts: []const Ast.ByteOffset,
+tok_i: TokenIndex,
+errors: std.ArrayListUnmanaged(AstError),
+nodes: Ast.NodeList,
+extra_data: std.ArrayListUnmanaged(Node.Index),
+scratch: std.ArrayListUnmanaged(Node.Index),
+
+const SmallSpan = union(enum) {
+    zero_or_one: Node.Index,
+    multi: Node.SubRange,
+};
+
+const Members = struct {
+    len: usize,
+    lhs: Node.Index,
+    rhs: Node.Index,
+    trailing: bool,
+
+    fn toSpan(self: Members, p: *Parse) !Node.SubRange {
+        if (self.len <= 2) {
+            const nodes = [2]Node.Index{ self.lhs, self.rhs };
+            return p.listToSpan(nodes[0..self.len]);
+        } else {
+            return Node.SubRange{ .start = self.lhs, .end = self.rhs };
+        }
+    }
+};
+
+fn listToSpan(p: *Parse, list: []const Node.Index) !Node.SubRange {
+    try p.extra_data.appendSlice(p.gpa, list);
+    return Node.SubRange{
+        .start = @intCast(Node.Index, p.extra_data.items.len - list.len),
+        .end = @intCast(Node.Index, p.extra_data.items.len),
+    };
+}
+
+fn addNode(p: *Parse, elem: Ast.NodeList.Elem) Allocator.Error!Node.Index {
+    const result = @intCast(Node.Index, p.nodes.len);
+    try p.nodes.append(p.gpa, elem);
+    return result;
+}
+
+fn setNode(p: *Parse, i: usize, elem: Ast.NodeList.Elem) Node.Index {
+    p.nodes.set(i, elem);
+    return @intCast(Node.Index, i);
+}
+
+fn reserveNode(p: *Parse, tag: Ast.Node.Tag) !usize {
+    try p.nodes.resize(p.gpa, p.nodes.len + 1);
+    p.nodes.items(.tag)[p.nodes.len - 1] = tag;
+    return p.nodes.len - 1;
+}
+
+fn unreserveNode(p: *Parse, node_index: usize) void {
+    if (p.nodes.len == node_index) {
+        p.nodes.resize(p.gpa, p.nodes.len - 1) catch unreachable;
+    } else {
+        // There is zombie node left in the tree, let's make it as inoffensive as possible
+        // (sadly there's no no-op node)
+        p.nodes.items(.tag)[node_index] = .unreachable_literal;
+        p.nodes.items(.main_token)[node_index] = p.tok_i;
+    }
+}
+
+fn addExtra(p: *Parse, extra: anytype) Allocator.Error!Node.Index {
+    const fields = std.meta.fields(@TypeOf(extra));
+    try p.extra_data.ensureUnusedCapacity(p.gpa, fields.len);
+    const result = @intCast(u32, p.extra_data.items.len);
+    inline for (fields) |field| {
+        comptime assert(field.type == Node.Index);
+        p.extra_data.appendAssumeCapacity(@field(extra, field.name));
+    }
+    return result;
+}
+
+fn warnExpected(p: *Parse, expected_token: Token.Tag) error{OutOfMemory}!void {
+    @setCold(true);
+    try p.warnMsg(.{
+        .tag = .expected_token,
+        .token = p.tok_i,
+        .extra = .{ .expected_tag = expected_token },
+    });
+}
+
+fn warn(p: *Parse, error_tag: AstError.Tag) error{OutOfMemory}!void {
+    @setCold(true);
+    try p.warnMsg(.{ .tag = error_tag, .token = p.tok_i });
+}
+
+fn warnMsg(p: *Parse, msg: Ast.Error) error{OutOfMemory}!void {
+    @setCold(true);
+    switch (msg.tag) {
+        .expected_semi_after_decl,
+        .expected_semi_after_stmt,
+        .expected_comma_after_field,
+        .expected_comma_after_arg,
+        .expected_comma_after_param,
+        .expected_comma_after_initializer,
+        .expected_comma_after_switch_prong,
+        .expected_semi_or_else,
+        .expected_semi_or_lbrace,
+        .expected_token,
+        .expected_block,
+        .expected_block_or_assignment,
+        .expected_block_or_expr,
+        .expected_block_or_field,
+        .expected_expr,
+        .expected_expr_or_assignment,
+        .expected_fn,
+        .expected_inlinable,
+        .expected_labelable,
+        .expected_param_list,
+        .expected_prefix_expr,
+        .expected_primary_type_expr,
+        .expected_pub_item,
+        .expected_return_type,
+        .expected_suffix_op,
+        .expected_type_expr,
+        .expected_var_decl,
+        .expected_var_decl_or_fn,
+        .expected_loop_payload,
+        .expected_container,
+        => if (msg.token != 0 and !p.tokensOnSameLine(msg.token - 1, msg.token)) {
+            var copy = msg;
+            copy.token_is_prev = true;
+            copy.token -= 1;
+            return p.errors.append(p.gpa, copy);
+        },
+        else => {},
+    }
+    try p.errors.append(p.gpa, msg);
+}
+
+fn fail(p: *Parse, tag: Ast.Error.Tag) error{ ParseError, OutOfMemory } {
+    @setCold(true);
+    return p.failMsg(.{ .tag = tag, .token = p.tok_i });
+}
+
+fn failExpected(p: *Parse, expected_token: Token.Tag) error{ ParseError, OutOfMemory } {
+    @setCold(true);
+    return p.failMsg(.{
+        .tag = .expected_token,
+        .token = p.tok_i,
+        .extra = .{ .expected_tag = expected_token },
+    });
+}
+
+fn failMsg(p: *Parse, msg: Ast.Error) error{ ParseError, OutOfMemory } {
+    @setCold(true);
+    try p.warnMsg(msg);
+    return error.ParseError;
+}
+
+/// Root <- skip container_doc_comment? ContainerMembers eof
+pub fn parseRoot(p: *Parse) !void {
+    // Root node must be index 0.
+    p.nodes.appendAssumeCapacity(.{
+        .tag = .root,
+        .main_token = 0,
+        .data = undefined,
+    });
+    const root_members = try p.parseContainerMembers();
+    const root_decls = try root_members.toSpan(p);
+    if (p.token_tags[p.tok_i] != .eof) {
+        try p.warnExpected(.eof);
+    }
+    p.nodes.items(.data)[0] = .{
+        .lhs = root_decls.start,
+        .rhs = root_decls.end,
+    };
+}
+
+/// Parse in ZON mode. Subset of the language.
+/// TODO: set a flag in Parse struct, and honor that flag
+/// by emitting compilation errors when non-zon nodes are encountered.
+pub fn parseZon(p: *Parse) !void {
+    // We must use index 0 so that 0 can be used as null elsewhere.
+    p.nodes.appendAssumeCapacity(.{
+        .tag = .root,
+        .main_token = 0,
+        .data = undefined,
+    });
+    const node_index = p.expectExpr() catch |err| switch (err) {
+        error.ParseError => {
+            assert(p.errors.items.len > 0);
+            return;
+        },
+        else => |e| return e,
+    };
+    if (p.token_tags[p.tok_i] != .eof) {
+        try p.warnExpected(.eof);
+    }
+    p.nodes.items(.data)[0] = .{
+        .lhs = node_index,
+        .rhs = undefined,
+    };
+}
+
+/// ContainerMembers <- ContainerDeclarations (ContainerField COMMA)* (ContainerField / ContainerDeclarations)
+///
+/// ContainerDeclarations
+///     <- TestDecl ContainerDeclarations
+///      / ComptimeDecl ContainerDeclarations
+///      / doc_comment? KEYWORD_pub? Decl ContainerDeclarations
+///      /
+///
+/// ComptimeDecl <- KEYWORD_comptime Block
+fn parseContainerMembers(p: *Parse) !Members {
+    const scratch_top = p.scratch.items.len;
+    defer p.scratch.shrinkRetainingCapacity(scratch_top);
+
+    var field_state: union(enum) {
+        /// No fields have been seen.
+        none,
+        /// Currently parsing fields.
+        seen,
+        /// Saw fields and then a declaration after them.
+        /// Payload is first token of previous declaration.
+        end: Node.Index,
+        /// There was a declaration between fields, don't report more errors.
+        err,
+    } = .none;
+
+    var last_field: TokenIndex = undefined;
+
+    // Skip container doc comments.
+    while (p.eatToken(.container_doc_comment)) |_| {}
+
+    var trailing = false;
+    while (true) {
+        const doc_comment = try p.eatDocComments();
+
+        switch (p.token_tags[p.tok_i]) {
+            .keyword_test => {
+                if (doc_comment) |some| {
+                    try p.warnMsg(.{ .tag = .test_doc_comment, .token = some });
+                }
+                const test_decl_node = try p.expectTestDeclRecoverable();
+                if (test_decl_node != 0) {
+                    if (field_state == .seen) {
+                        field_state = .{ .end = test_decl_node };
+                    }
+                    try p.scratch.append(p.gpa, test_decl_node);
+                }
+                trailing = false;
+            },
+            .keyword_comptime => switch (p.token_tags[p.tok_i + 1]) {
+                .l_brace => {
+                    if (doc_comment) |some| {
+                        try p.warnMsg(.{ .tag = .comptime_doc_comment, .token = some });
+                    }
+                    const comptime_token = p.nextToken();
+                    const block = p.parseBlock() catch |err| switch (err) {
+                        error.OutOfMemory => return error.OutOfMemory,
+                        error.ParseError => blk: {
+                            p.findNextContainerMember();
+                            break :blk null_node;
+                        },
+                    };
+                    if (block != 0) {
+                        const comptime_node = try p.addNode(.{
+                            .tag = .@"comptime",
+                            .main_token = comptime_token,
+                            .data = .{
+                                .lhs = block,
+                                .rhs = undefined,
+                            },
+                        });
+                        if (field_state == .seen) {
+                            field_state = .{ .end = comptime_node };
+                        }
+                        try p.scratch.append(p.gpa, comptime_node);
+                    }
+                    trailing = false;
+                },
+                else => {
+                    const identifier = p.tok_i;
+                    defer last_field = identifier;
+                    const container_field = p.expectContainerField() catch |err| switch (err) {
+                        error.OutOfMemory => return error.OutOfMemory,
+                        error.ParseError => {
+                            p.findNextContainerMember();
+                            continue;
+                        },
+                    };
+                    switch (field_state) {
+                        .none => field_state = .seen,
+                        .err, .seen => {},
+                        .end => |node| {
+                            try p.warnMsg(.{
+                                .tag = .decl_between_fields,
+                                .token = p.nodes.items(.main_token)[node],
+                            });
+                            try p.warnMsg(.{
+                                .tag = .previous_field,
+                                .is_note = true,
+                                .token = last_field,
+                            });
+                            try p.warnMsg(.{
+                                .tag = .next_field,
+                                .is_note = true,
+                                .token = identifier,
+                            });
+                            // Continue parsing; error will be reported later.
+                            field_state = .err;
+                        },
+                    }
+                    try p.scratch.append(p.gpa, container_field);
+                    switch (p.token_tags[p.tok_i]) {
+                        .comma => {
+                            p.tok_i += 1;
+                            trailing = true;
+                            continue;
+                        },
+                        .r_brace, .eof => {
+                            trailing = false;
+                            break;
+                        },
+                        else => {},
+                    }
+                    // There is not allowed to be a decl after a field with no comma.
+                    // Report error but recover parser.
+                    try p.warn(.expected_comma_after_field);
+                    p.findNextContainerMember();
+                },
+            },
+            .keyword_pub => {
+                p.tok_i += 1;
+                const top_level_decl = try p.expectTopLevelDeclRecoverable();
+                if (top_level_decl != 0) {
+                    if (field_state == .seen) {
+                        field_state = .{ .end = top_level_decl };
+                    }
+                    try p.scratch.append(p.gpa, top_level_decl);
+                }
+                trailing = p.token_tags[p.tok_i - 1] == .semicolon;
+            },
+            .keyword_usingnamespace => {
+                const node = try p.expectUsingNamespaceRecoverable();
+                if (node != 0) {
+                    if (field_state == .seen) {
+                        field_state = .{ .end = node };
+                    }
+                    try p.scratch.append(p.gpa, node);
+                }
+                trailing = p.token_tags[p.tok_i - 1] == .semicolon;
+            },
+            .keyword_const,
+            .keyword_var,
+            .keyword_threadlocal,
+            .keyword_export,
+            .keyword_extern,
+            .keyword_inline,
+            .keyword_noinline,
+            .keyword_fn,
+            => {
+                const top_level_decl = try p.expectTopLevelDeclRecoverable();
+                if (top_level_decl != 0) {
+                    if (field_state == .seen) {
+                        field_state = .{ .end = top_level_decl };
+                    }
+                    try p.scratch.append(p.gpa, top_level_decl);
+                }
+                trailing = p.token_tags[p.tok_i - 1] == .semicolon;
+            },
+            .eof, .r_brace => {
+                if (doc_comment) |tok| {
+                    try p.warnMsg(.{
+                        .tag = .unattached_doc_comment,
+                        .token = tok,
+                    });
+                }
+                break;
+            },
+            else => {
+                const c_container = p.parseCStyleContainer() catch |err| switch (err) {
+                    error.OutOfMemory => return error.OutOfMemory,
+                    error.ParseError => false,
+                };
+                if (c_container) continue;
+
+                const identifier = p.tok_i;
+                defer last_field = identifier;
+                const container_field = p.expectContainerField() catch |err| switch (err) {
+                    error.OutOfMemory => return error.OutOfMemory,
+                    error.ParseError => {
+                        p.findNextContainerMember();
+                        continue;
+                    },
+                };
+                switch (field_state) {
+                    .none => field_state = .seen,
+                    .err, .seen => {},
+                    .end => |node| {
+                        try p.warnMsg(.{
+                            .tag = .decl_between_fields,
+                            .token = p.nodes.items(.main_token)[node],
+                        });
+                        try p.warnMsg(.{
+                            .tag = .previous_field,
+                            .is_note = true,
+                            .token = last_field,
+                        });
+                        try p.warnMsg(.{
+                            .tag = .next_field,
+                            .is_note = true,
+                            .token = identifier,
+                        });
+                        // Continue parsing; error will be reported later.
+                        field_state = .err;
+                    },
+                }
+                try p.scratch.append(p.gpa, container_field);
+                switch (p.token_tags[p.tok_i]) {
+                    .comma => {
+                        p.tok_i += 1;
+                        trailing = true;
+                        continue;
+                    },
+                    .r_brace, .eof => {
+                        trailing = false;
+                        break;
+                    },
+                    else => {},
+                }
+                // There is not allowed to be a decl after a field with no comma.
+                // Report error but recover parser.
+                try p.warn(.expected_comma_after_field);
+                if (p.token_tags[p.tok_i] == .semicolon and p.token_tags[identifier] == .identifier) {
+                    try p.warnMsg(.{
+                        .tag = .var_const_decl,
+                        .is_note = true,
+                        .token = identifier,
+                    });
+                }
+                p.findNextContainerMember();
+                continue;
+            },
+        }
+    }
+
+    const items = p.scratch.items[scratch_top..];
+    switch (items.len) {
+        0 => return Members{
+            .len = 0,
+            .lhs = 0,
+            .rhs = 0,
+            .trailing = trailing,
+        },
+        1 => return Members{
+            .len = 1,
+            .lhs = items[0],
+            .rhs = 0,
+            .trailing = trailing,
+        },
+        2 => return Members{
+            .len = 2,
+            .lhs = items[0],
+            .rhs = items[1],
+            .trailing = trailing,
+        },
+        else => {
+            const span = try p.listToSpan(items);
+            return Members{
+                .len = items.len,
+                .lhs = span.start,
+                .rhs = span.end,
+                .trailing = trailing,
+            };
+        },
+    }
+}
+
+/// Attempts to find next container member by searching for certain tokens
+fn findNextContainerMember(p: *Parse) void {
+    var level: u32 = 0;
+    while (true) {
+        const tok = p.nextToken();
+        switch (p.token_tags[tok]) {
+            // Any of these can start a new top level declaration.
+            .keyword_test,
+            .keyword_comptime,
+            .keyword_pub,
+            .keyword_export,
+            .keyword_extern,
+            .keyword_inline,
+            .keyword_noinline,
+            .keyword_usingnamespace,
+            .keyword_threadlocal,
+            .keyword_const,
+            .keyword_var,
+            .keyword_fn,
+            => {
+                if (level == 0) {
+                    p.tok_i -= 1;
+                    return;
+                }
+            },
+            .identifier => {
+                if (p.token_tags[tok + 1] == .comma and level == 0) {
+                    p.tok_i -= 1;
+                    return;
+                }
+            },
+            .comma, .semicolon => {
+                // this decl was likely meant to end here
+                if (level == 0) {
+                    return;
+                }
+            },
+            .l_paren, .l_bracket, .l_brace => level += 1,
+            .r_paren, .r_bracket => {
+                if (level != 0) level -= 1;
+            },
+            .r_brace => {
+                if (level == 0) {
+                    // end of container, exit
+                    p.tok_i -= 1;
+                    return;
+                }
+                level -= 1;
+            },
+            .eof => {
+                p.tok_i -= 1;
+                return;
+            },
+            else => {},
+        }
+    }
+}
+
+/// Attempts to find the next statement by searching for a semicolon
+fn findNextStmt(p: *Parse) void {
+    var level: u32 = 0;
+    while (true) {
+        const tok = p.nextToken();
+        switch (p.token_tags[tok]) {
+            .l_brace => level += 1,
+            .r_brace => {
+                if (level == 0) {
+                    p.tok_i -= 1;
+                    return;
+                }
+                level -= 1;
+            },
+            .semicolon => {
+                if (level == 0) {
+                    return;
+                }
+            },
+            .eof => {
+                p.tok_i -= 1;
+                return;
+            },
+            else => {},
+        }
+    }
+}
+
+/// TestDecl <- KEYWORD_test (STRINGLITERALSINGLE / IDENTIFIER)? Block
+fn expectTestDecl(p: *Parse) !Node.Index {
+    const test_token = p.assertToken(.keyword_test);
+    const name_token = switch (p.token_tags[p.nextToken()]) {
+        .string_literal, .identifier => p.tok_i - 1,
+        else => blk: {
+            p.tok_i -= 1;
+            break :blk null;
+        },
+    };
+    const block_node = try p.parseBlock();
+    if (block_node == 0) return p.fail(.expected_block);
+    return p.addNode(.{
+        .tag = .test_decl,
+        .main_token = test_token,
+        .data = .{
+            .lhs = name_token orelse 0,
+            .rhs = block_node,
+        },
+    });
+}
+
+fn expectTestDeclRecoverable(p: *Parse) error{OutOfMemory}!Node.Index {
+    return p.expectTestDecl() catch |err| switch (err) {
+        error.OutOfMemory => return error.OutOfMemory,
+        error.ParseError => {
+            p.findNextContainerMember();
+            return null_node;
+        },
+    };
+}
+
+/// Decl
+///     <- (KEYWORD_export / KEYWORD_extern STRINGLITERALSINGLE? / (KEYWORD_inline / KEYWORD_noinline))? FnProto (SEMICOLON / Block)
+///      / (KEYWORD_export / KEYWORD_extern STRINGLITERALSINGLE?)? KEYWORD_threadlocal? VarDecl
+///      / KEYWORD_usingnamespace Expr SEMICOLON
+fn expectTopLevelDecl(p: *Parse) !Node.Index {
+    const extern_export_inline_token = p.nextToken();
+    var is_extern: bool = false;
+    var expect_fn: bool = false;
+    var expect_var_or_fn: bool = false;
+    switch (p.token_tags[extern_export_inline_token]) {
+        .keyword_extern => {
+            _ = p.eatToken(.string_literal);
+            is_extern = true;
+            expect_var_or_fn = true;
+        },
+        .keyword_export => expect_var_or_fn = true,
+        .keyword_inline, .keyword_noinline => expect_fn = true,
+        else => p.tok_i -= 1,
+    }
+    const fn_proto = try p.parseFnProto();
+    if (fn_proto != 0) {
+        switch (p.token_tags[p.tok_i]) {
+            .semicolon => {
+                p.tok_i += 1;
+                return fn_proto;
+            },
+            .l_brace => {
+                if (is_extern) {
+                    try p.warnMsg(.{ .tag = .extern_fn_body, .token = extern_export_inline_token });
+                    return null_node;
+                }
+                const fn_decl_index = try p.reserveNode(.fn_decl);
+                errdefer p.unreserveNode(fn_decl_index);
+
+                const body_block = try p.parseBlock();
+                assert(body_block != 0);
+                return p.setNode(fn_decl_index, .{
+                    .tag = .fn_decl,
+                    .main_token = p.nodes.items(.main_token)[fn_proto],
+                    .data = .{
+                        .lhs = fn_proto,
+                        .rhs = body_block,
+                    },
+                });
+            },
+            else => {
+                // Since parseBlock only return error.ParseError on
+                // a missing '}' we can assume this function was
+                // supposed to end here.
+                try p.warn(.expected_semi_or_lbrace);
+                return null_node;
+            },
+        }
+    }
+    if (expect_fn) {
+        try p.warn(.expected_fn);
+        return error.ParseError;
+    }
+
+    const thread_local_token = p.eatToken(.keyword_threadlocal);
+    const var_decl = try p.parseVarDecl();
+    if (var_decl != 0) {
+        try p.expectSemicolon(.expected_semi_after_decl, false);
+        return var_decl;
+    }
+    if (thread_local_token != null) {
+        return p.fail(.expected_var_decl);
+    }
+    if (expect_var_or_fn) {
+        return p.fail(.expected_var_decl_or_fn);
+    }
+    if (p.token_tags[p.tok_i] != .keyword_usingnamespace) {
+        return p.fail(.expected_pub_item);
+    }
+    return p.expectUsingNamespace();
+}
+
+fn expectTopLevelDeclRecoverable(p: *Parse) error{OutOfMemory}!Node.Index {
+    return p.expectTopLevelDecl() catch |err| switch (err) {
+        error.OutOfMemory => return error.OutOfMemory,
+        error.ParseError => {
+            p.findNextContainerMember();
+            return null_node;
+        },
+    };
+}
+
+fn expectUsingNamespace(p: *Parse) !Node.Index {
+    const usingnamespace_token = p.assertToken(.keyword_usingnamespace);
+    const expr = try p.expectExpr();
+    try p.expectSemicolon(.expected_semi_after_decl, false);
+    return p.addNode(.{
+        .tag = .@"usingnamespace",
+        .main_token = usingnamespace_token,
+        .data = .{
+            .lhs = expr,
+            .rhs = undefined,
+        },
+    });
+}
+
+fn expectUsingNamespaceRecoverable(p: *Parse) error{OutOfMemory}!Node.Index {
+    return p.expectUsingNamespace() catch |err| switch (err) {
+        error.OutOfMemory => return error.OutOfMemory,
+        error.ParseError => {
+            p.findNextContainerMember();
+            return null_node;
+        },
+    };
+}
+
+/// FnProto <- KEYWORD_fn IDENTIFIER? LPAREN ParamDeclList RPAREN ByteAlign? AddrSpace? LinkSection? CallConv? EXCLAMATIONMARK? TypeExpr
+fn parseFnProto(p: *Parse) !Node.Index {
+    const fn_token = p.eatToken(.keyword_fn) orelse return null_node;
+
+    // We want the fn proto node to be before its children in the array.
+    const fn_proto_index = try p.reserveNode(.fn_proto);
+    errdefer p.unreserveNode(fn_proto_index);
+
+    _ = p.eatToken(.identifier);
+    const params = try p.parseParamDeclList();
+    const align_expr = try p.parseByteAlign();
+    const addrspace_expr = try p.parseAddrSpace();
+    const section_expr = try p.parseLinkSection();
+    const callconv_expr = try p.parseCallconv();
+    _ = p.eatToken(.bang);
+
+    const return_type_expr = try p.parseTypeExpr();
+    if (return_type_expr == 0) {
+        // most likely the user forgot to specify the return type.
+        // Mark return type as invalid and try to continue.
+        try p.warn(.expected_return_type);
+    }
+
+    if (align_expr == 0 and section_expr == 0 and callconv_expr == 0 and addrspace_expr == 0) {
+        switch (params) {
+            .zero_or_one => |param| return p.setNode(fn_proto_index, .{
+                .tag = .fn_proto_simple,
+                .main_token = fn_token,
+                .data = .{
+                    .lhs = param,
+                    .rhs = return_type_expr,
+                },
+            }),
+            .multi => |span| {
+                return p.setNode(fn_proto_index, .{
+                    .tag = .fn_proto_multi,
+                    .main_token = fn_token,
+                    .data = .{
+                        .lhs = try p.addExtra(Node.SubRange{
+                            .start = span.start,
+                            .end = span.end,
+                        }),
+                        .rhs = return_type_expr,
+                    },
+                });
+            },
+        }
+    }
+    switch (params) {
+        .zero_or_one => |param| return p.setNode(fn_proto_index, .{
+            .tag = .fn_proto_one,
+            .main_token = fn_token,
+            .data = .{
+                .lhs = try p.addExtra(Node.FnProtoOne{
+                    .param = param,
+                    .align_expr = align_expr,
+                    .addrspace_expr = addrspace_expr,
+                    .section_expr = section_expr,
+                    .callconv_expr = callconv_expr,
+                }),
+                .rhs = return_type_expr,
+            },
+        }),
+        .multi => |span| {
+            return p.setNode(fn_proto_index, .{
+                .tag = .fn_proto,
+                .main_token = fn_token,
+                .data = .{
+                    .lhs = try p.addExtra(Node.FnProto{
+                        .params_start = span.start,
+                        .params_end = span.end,
+                        .align_expr = align_expr,
+                        .addrspace_expr = addrspace_expr,
+                        .section_expr = section_expr,
+                        .callconv_expr = callconv_expr,
+                    }),
+                    .rhs = return_type_expr,
+                },
+            });
+        },
+    }
+}
+
+/// VarDecl <- (KEYWORD_const / KEYWORD_var) IDENTIFIER (COLON TypeExpr)? ByteAlign? AddrSpace? LinkSection? (EQUAL Expr)? SEMICOLON
+fn parseVarDecl(p: *Parse) !Node.Index {
+    const mut_token = p.eatToken(.keyword_const) orelse
+        p.eatToken(.keyword_var) orelse
+        return null_node;
+
+    _ = try p.expectToken(.identifier);
+    const type_node: Node.Index = if (p.eatToken(.colon) == null) 0 else try p.expectTypeExpr();
+    const align_node = try p.parseByteAlign();
+    const addrspace_node = try p.parseAddrSpace();
+    const section_node = try p.parseLinkSection();
+    const init_node: Node.Index = switch (p.token_tags[p.tok_i]) {
+        .equal_equal => blk: {
+            try p.warn(.wrong_equal_var_decl);
+            p.tok_i += 1;
+            break :blk try p.expectExpr();
+        },
+        .equal => blk: {
+            p.tok_i += 1;
+            break :blk try p.expectExpr();
+        },
+        else => 0,
+    };
+    if (section_node == 0 and addrspace_node == 0) {
+        if (align_node == 0) {
+            return p.addNode(.{
+                .tag = .simple_var_decl,
+                .main_token = mut_token,
+                .data = .{
+                    .lhs = type_node,
+                    .rhs = init_node,
+                },
+            });
+        } else if (type_node == 0) {
+            return p.addNode(.{
+                .tag = .aligned_var_decl,
+                .main_token = mut_token,
+                .data = .{
+                    .lhs = align_node,
+                    .rhs = init_node,
+                },
+            });
+        } else {
+            return p.addNode(.{
+                .tag = .local_var_decl,
+                .main_token = mut_token,
+                .data = .{
+                    .lhs = try p.addExtra(Node.LocalVarDecl{
+                        .type_node = type_node,
+                        .align_node = align_node,
+                    }),
+                    .rhs = init_node,
+                },
+            });
+        }
+    } else {
+        return p.addNode(.{
+            .tag = .global_var_decl,
+            .main_token = mut_token,
+            .data = .{
+                .lhs = try p.addExtra(Node.GlobalVarDecl{
+                    .type_node = type_node,
+                    .align_node = align_node,
+                    .addrspace_node = addrspace_node,
+                    .section_node = section_node,
+                }),
+                .rhs = init_node,
+            },
+        });
+    }
+}
+
+/// ContainerField
+///     <- doc_comment? KEYWORD_comptime? IDENTIFIER (COLON TypeExpr)? ByteAlign? (EQUAL Expr)?
+///      / doc_comment? KEYWORD_comptime? (IDENTIFIER COLON)? !KEYWORD_fn TypeExpr ByteAlign? (EQUAL Expr)?
+fn expectContainerField(p: *Parse) !Node.Index {
+    var main_token = p.tok_i;
+    _ = p.eatToken(.keyword_comptime);
+    const tuple_like = p.token_tags[p.tok_i] != .identifier or p.token_tags[p.tok_i + 1] != .colon;
+    if (!tuple_like) {
+        main_token = p.assertToken(.identifier);
+    }
+
+    var align_expr: Node.Index = 0;
+    var type_expr: Node.Index = 0;
+    if (p.eatToken(.colon) != null or tuple_like) {
+        type_expr = try p.expectTypeExpr();
+        align_expr = try p.parseByteAlign();
+    }
+
+    const value_expr: Node.Index = if (p.eatToken(.equal) == null) 0 else try p.expectExpr();
+
+    if (align_expr == 0) {
+        return p.addNode(.{
+            .tag = .container_field_init,
+            .main_token = main_token,
+            .data = .{
+                .lhs = type_expr,
+                .rhs = value_expr,
+            },
+        });
+    } else if (value_expr == 0) {
+        return p.addNode(.{
+            .tag = .container_field_align,
+            .main_token = main_token,
+            .data = .{
+                .lhs = type_expr,
+                .rhs = align_expr,
+            },
+        });
+    } else {
+        return p.addNode(.{
+            .tag = .container_field,
+            .main_token = main_token,
+            .data = .{
+                .lhs = type_expr,
+                .rhs = try p.addExtra(Node.ContainerField{
+                    .value_expr = value_expr,
+                    .align_expr = align_expr,
+                }),
+            },
+        });
+    }
+}
+
+/// Statement
+///     <- KEYWORD_comptime? VarDecl
+///      / KEYWORD_comptime BlockExprStatement
+///      / KEYWORD_nosuspend BlockExprStatement
+///      / KEYWORD_suspend BlockExprStatement
+///      / KEYWORD_defer BlockExprStatement
+///      / KEYWORD_errdefer Payload? BlockExprStatement
+///      / IfStatement
+///      / LabeledStatement
+///      / SwitchExpr
+///      / AssignExpr SEMICOLON
+fn parseStatement(p: *Parse, allow_defer_var: bool) Error!Node.Index {
+    const comptime_token = p.eatToken(.keyword_comptime);
+
+    if (allow_defer_var) {
+        const var_decl = try p.parseVarDecl();
+        if (var_decl != 0) {
+            try p.expectSemicolon(.expected_semi_after_decl, true);
+            return var_decl;
+        }
+    }
+
+    if (comptime_token) |token| {
+        return p.addNode(.{
+            .tag = .@"comptime",
+            .main_token = token,
+            .data = .{
+                .lhs = try p.expectBlockExprStatement(),
+                .rhs = undefined,
+            },
+        });
+    }
+
+    switch (p.token_tags[p.tok_i]) {
+        .keyword_nosuspend => {
+            return p.addNode(.{
+                .tag = .@"nosuspend",
+                .main_token = p.nextToken(),
+                .data = .{
+                    .lhs = try p.expectBlockExprStatement(),
+                    .rhs = undefined,
+                },
+            });
+        },
+        .keyword_suspend => {
+            const token = p.nextToken();
+            const block_expr = try p.expectBlockExprStatement();
+            return p.addNode(.{
+                .tag = .@"suspend",
+                .main_token = token,
+                .data = .{
+                    .lhs = block_expr,
+                    .rhs = undefined,
+                },
+            });
+        },
+        .keyword_defer => if (allow_defer_var) return p.addNode(.{
+            .tag = .@"defer",
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = undefined,
+                .rhs = try p.expectBlockExprStatement(),
+            },
+        }),
+        .keyword_errdefer => if (allow_defer_var) return p.addNode(.{
+            .tag = .@"errdefer",
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = try p.parsePayload(),
+                .rhs = try p.expectBlockExprStatement(),
+            },
+        }),
+        .keyword_switch => return p.expectSwitchExpr(),
+        .keyword_if => return p.expectIfStatement(),
+        .keyword_enum, .keyword_struct, .keyword_union => {
+            const identifier = p.tok_i + 1;
+            if (try p.parseCStyleContainer()) {
+                // Return something so that `expectStatement` is happy.
+                return p.addNode(.{
+                    .tag = .identifier,
+                    .main_token = identifier,
+                    .data = .{
+                        .lhs = undefined,
+                        .rhs = undefined,
+                    },
+                });
+            }
+        },
+        else => {},
+    }
+
+    const labeled_statement = try p.parseLabeledStatement();
+    if (labeled_statement != 0) return labeled_statement;
+
+    const assign_expr = try p.parseAssignExpr();
+    if (assign_expr != 0) {
+        try p.expectSemicolon(.expected_semi_after_stmt, true);
+        return assign_expr;
+    }
+
+    return null_node;
+}
+
+fn expectStatement(p: *Parse, allow_defer_var: bool) !Node.Index {
+    const statement = try p.parseStatement(allow_defer_var);
+    if (statement == 0) {
+        return p.fail(.expected_statement);
+    }
+    return statement;
+}
+
+/// If a parse error occurs, reports an error, but then finds the next statement
+/// and returns that one instead. If a parse error occurs but there is no following
+/// statement, returns 0.
+fn expectStatementRecoverable(p: *Parse) Error!Node.Index {
+    while (true) {
+        return p.expectStatement(true) catch |err| switch (err) {
+            error.OutOfMemory => return error.OutOfMemory,
+            error.ParseError => {
+                p.findNextStmt(); // Try to skip to the next statement.
+                switch (p.token_tags[p.tok_i]) {
+                    .r_brace => return null_node,
+                    .eof => return error.ParseError,
+                    else => continue,
+                }
+            },
+        };
+    }
+}
+
+/// IfStatement
+///     <- IfPrefix BlockExpr ( KEYWORD_else Payload? Statement )?
+///      / IfPrefix AssignExpr ( SEMICOLON / KEYWORD_else Payload? Statement )
+fn expectIfStatement(p: *Parse) !Node.Index {
+    const if_token = p.assertToken(.keyword_if);
+    _ = try p.expectToken(.l_paren);
+    const condition = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    _ = try p.parsePtrPayload();
+
+    // TODO propose to change the syntax so that semicolons are always required
+    // inside if statements, even if there is an `else`.
+    var else_required = false;
+    const then_expr = blk: {
+        const block_expr = try p.parseBlockExpr();
+        if (block_expr != 0) break :blk block_expr;
+        const assign_expr = try p.parseAssignExpr();
+        if (assign_expr == 0) {
+            return p.fail(.expected_block_or_assignment);
+        }
+        if (p.eatToken(.semicolon)) |_| {
+            return p.addNode(.{
+                .tag = .if_simple,
+                .main_token = if_token,
+                .data = .{
+                    .lhs = condition,
+                    .rhs = assign_expr,
+                },
+            });
+        }
+        else_required = true;
+        break :blk assign_expr;
+    };
+    _ = p.eatToken(.keyword_else) orelse {
+        if (else_required) {
+            try p.warn(.expected_semi_or_else);
+        }
+        return p.addNode(.{
+            .tag = .if_simple,
+            .main_token = if_token,
+            .data = .{
+                .lhs = condition,
+                .rhs = then_expr,
+            },
+        });
+    };
+    _ = try p.parsePayload();
+    const else_expr = try p.expectStatement(false);
+    return p.addNode(.{
+        .tag = .@"if",
+        .main_token = if_token,
+        .data = .{
+            .lhs = condition,
+            .rhs = try p.addExtra(Node.If{
+                .then_expr = then_expr,
+                .else_expr = else_expr,
+            }),
+        },
+    });
+}
+
+/// LabeledStatement <- BlockLabel? (Block / LoopStatement)
+fn parseLabeledStatement(p: *Parse) !Node.Index {
+    const label_token = p.parseBlockLabel();
+    const block = try p.parseBlock();
+    if (block != 0) return block;
+
+    const loop_stmt = try p.parseLoopStatement();
+    if (loop_stmt != 0) return loop_stmt;
+
+    if (label_token != 0) {
+        const after_colon = p.tok_i;
+        const node = try p.parseTypeExpr();
+        if (node != 0) {
+            const a = try p.parseByteAlign();
+            const b = try p.parseAddrSpace();
+            const c = try p.parseLinkSection();
+            const d = if (p.eatToken(.equal) == null) 0 else try p.expectExpr();
+            if (a != 0 or b != 0 or c != 0 or d != 0) {
+                return p.failMsg(.{ .tag = .expected_var_const, .token = label_token });
+            }
+        }
+        return p.failMsg(.{ .tag = .expected_labelable, .token = after_colon });
+    }
+
+    return null_node;
+}
+
+/// LoopStatement <- KEYWORD_inline? (ForStatement / WhileStatement)
+fn parseLoopStatement(p: *Parse) !Node.Index {
+    const inline_token = p.eatToken(.keyword_inline);
+
+    const for_statement = try p.parseForStatement();
+    if (for_statement != 0) return for_statement;
+
+    const while_statement = try p.parseWhileStatement();
+    if (while_statement != 0) return while_statement;
+
+    if (inline_token == null) return null_node;
+
+    // If we've seen "inline", there should have been a "for" or "while"
+    return p.fail(.expected_inlinable);
+}
+
+/// ForPrefix <- KEYWORD_for LPAREN Expr RPAREN PtrIndexPayload
+///
+/// ForStatement
+///     <- ForPrefix BlockExpr ( KEYWORD_else Statement )?
+///      / ForPrefix AssignExpr ( SEMICOLON / KEYWORD_else Statement )
+fn parseForStatement(p: *Parse) !Node.Index {
+    const for_token = p.eatToken(.keyword_for) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const array_expr = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    const found_payload = try p.parsePtrIndexPayload();
+    if (found_payload == 0) try p.warn(.expected_loop_payload);
+
+    // TODO propose to change the syntax so that semicolons are always required
+    // inside while statements, even if there is an `else`.
+    var else_required = false;
+    const then_expr = blk: {
+        const block_expr = try p.parseBlockExpr();
+        if (block_expr != 0) break :blk block_expr;
+        const assign_expr = try p.parseAssignExpr();
+        if (assign_expr == 0) {
+            return p.fail(.expected_block_or_assignment);
+        }
+        if (p.eatToken(.semicolon)) |_| {
+            return p.addNode(.{
+                .tag = .for_simple,
+                .main_token = for_token,
+                .data = .{
+                    .lhs = array_expr,
+                    .rhs = assign_expr,
+                },
+            });
+        }
+        else_required = true;
+        break :blk assign_expr;
+    };
+    _ = p.eatToken(.keyword_else) orelse {
+        if (else_required) {
+            try p.warn(.expected_semi_or_else);
+        }
+        return p.addNode(.{
+            .tag = .for_simple,
+            .main_token = for_token,
+            .data = .{
+                .lhs = array_expr,
+                .rhs = then_expr,
+            },
+        });
+    };
+    return p.addNode(.{
+        .tag = .@"for",
+        .main_token = for_token,
+        .data = .{
+            .lhs = array_expr,
+            .rhs = try p.addExtra(Node.If{
+                .then_expr = then_expr,
+                .else_expr = try p.expectStatement(false),
+            }),
+        },
+    });
+}
+
+/// WhilePrefix <- KEYWORD_while LPAREN Expr RPAREN PtrPayload? WhileContinueExpr?
+///
+/// WhileStatement
+///     <- WhilePrefix BlockExpr ( KEYWORD_else Payload? Statement )?
+///      / WhilePrefix AssignExpr ( SEMICOLON / KEYWORD_else Payload? Statement )
+fn parseWhileStatement(p: *Parse) !Node.Index {
+    const while_token = p.eatToken(.keyword_while) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const condition = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    _ = try p.parsePtrPayload();
+    const cont_expr = try p.parseWhileContinueExpr();
+
+    // TODO propose to change the syntax so that semicolons are always required
+    // inside while statements, even if there is an `else`.
+    var else_required = false;
+    const then_expr = blk: {
+        const block_expr = try p.parseBlockExpr();
+        if (block_expr != 0) break :blk block_expr;
+        const assign_expr = try p.parseAssignExpr();
+        if (assign_expr == 0) {
+            return p.fail(.expected_block_or_assignment);
+        }
+        if (p.eatToken(.semicolon)) |_| {
+            if (cont_expr == 0) {
+                return p.addNode(.{
+                    .tag = .while_simple,
+                    .main_token = while_token,
+                    .data = .{
+                        .lhs = condition,
+                        .rhs = assign_expr,
+                    },
+                });
+            } else {
+                return p.addNode(.{
+                    .tag = .while_cont,
+                    .main_token = while_token,
+                    .data = .{
+                        .lhs = condition,
+                        .rhs = try p.addExtra(Node.WhileCont{
+                            .cont_expr = cont_expr,
+                            .then_expr = assign_expr,
+                        }),
+                    },
+                });
+            }
+        }
+        else_required = true;
+        break :blk assign_expr;
+    };
+    _ = p.eatToken(.keyword_else) orelse {
+        if (else_required) {
+            try p.warn(.expected_semi_or_else);
+        }
+        if (cont_expr == 0) {
+            return p.addNode(.{
+                .tag = .while_simple,
+                .main_token = while_token,
+                .data = .{
+                    .lhs = condition,
+                    .rhs = then_expr,
+                },
+            });
+        } else {
+            return p.addNode(.{
+                .tag = .while_cont,
+                .main_token = while_token,
+                .data = .{
+                    .lhs = condition,
+                    .rhs = try p.addExtra(Node.WhileCont{
+                        .cont_expr = cont_expr,
+                        .then_expr = then_expr,
+                    }),
+                },
+            });
+        }
+    };
+    _ = try p.parsePayload();
+    const else_expr = try p.expectStatement(false);
+    return p.addNode(.{
+        .tag = .@"while",
+        .main_token = while_token,
+        .data = .{
+            .lhs = condition,
+            .rhs = try p.addExtra(Node.While{
+                .cont_expr = cont_expr,
+                .then_expr = then_expr,
+                .else_expr = else_expr,
+            }),
+        },
+    });
+}
+
+/// BlockExprStatement
+///     <- BlockExpr
+///      / AssignExpr SEMICOLON
+fn parseBlockExprStatement(p: *Parse) !Node.Index {
+    const block_expr = try p.parseBlockExpr();
+    if (block_expr != 0) {
+        return block_expr;
+    }
+    const assign_expr = try p.parseAssignExpr();
+    if (assign_expr != 0) {
+        try p.expectSemicolon(.expected_semi_after_stmt, true);
+        return assign_expr;
+    }
+    return null_node;
+}
+
+fn expectBlockExprStatement(p: *Parse) !Node.Index {
+    const node = try p.parseBlockExprStatement();
+    if (node == 0) {
+        return p.fail(.expected_block_or_expr);
+    }
+    return node;
+}
+
+/// BlockExpr <- BlockLabel? Block
+fn parseBlockExpr(p: *Parse) Error!Node.Index {
+    switch (p.token_tags[p.tok_i]) {
+        .identifier => {
+            if (p.token_tags[p.tok_i + 1] == .colon and
+                p.token_tags[p.tok_i + 2] == .l_brace)
+            {
+                p.tok_i += 2;
+                return p.parseBlock();
+            } else {
+                return null_node;
+            }
+        },
+        .l_brace => return p.parseBlock(),
+        else => return null_node,
+    }
+}
+
+/// AssignExpr <- Expr (AssignOp Expr)?
+///
+/// AssignOp
+///     <- ASTERISKEQUAL
+///      / ASTERISKPIPEEQUAL
+///      / SLASHEQUAL
+///      / PERCENTEQUAL
+///      / PLUSEQUAL
+///      / PLUSPIPEEQUAL
+///      / MINUSEQUAL
+///      / MINUSPIPEEQUAL
+///      / LARROW2EQUAL
+///      / LARROW2PIPEEQUAL
+///      / RARROW2EQUAL
+///      / AMPERSANDEQUAL
+///      / CARETEQUAL
+///      / PIPEEQUAL
+///      / ASTERISKPERCENTEQUAL
+///      / PLUSPERCENTEQUAL
+///      / MINUSPERCENTEQUAL
+///      / EQUAL
+fn parseAssignExpr(p: *Parse) !Node.Index {
+    const expr = try p.parseExpr();
+    if (expr == 0) return null_node;
+
+    const tag: Node.Tag = switch (p.token_tags[p.tok_i]) {
+        .asterisk_equal => .assign_mul,
+        .slash_equal => .assign_div,
+        .percent_equal => .assign_mod,
+        .plus_equal => .assign_add,
+        .minus_equal => .assign_sub,
+        .angle_bracket_angle_bracket_left_equal => .assign_shl,
+        .angle_bracket_angle_bracket_left_pipe_equal => .assign_shl_sat,
+        .angle_bracket_angle_bracket_right_equal => .assign_shr,
+        .ampersand_equal => .assign_bit_and,
+        .caret_equal => .assign_bit_xor,
+        .pipe_equal => .assign_bit_or,
+        .asterisk_percent_equal => .assign_mul_wrap,
+        .plus_percent_equal => .assign_add_wrap,
+        .minus_percent_equal => .assign_sub_wrap,
+        .asterisk_pipe_equal => .assign_mul_sat,
+        .plus_pipe_equal => .assign_add_sat,
+        .minus_pipe_equal => .assign_sub_sat,
+        .equal => .assign,
+        else => return expr,
+    };
+    return p.addNode(.{
+        .tag = tag,
+        .main_token = p.nextToken(),
+        .data = .{
+            .lhs = expr,
+            .rhs = try p.expectExpr(),
+        },
+    });
+}
+
+fn expectAssignExpr(p: *Parse) !Node.Index {
+    const expr = try p.parseAssignExpr();
+    if (expr == 0) {
+        return p.fail(.expected_expr_or_assignment);
+    }
+    return expr;
+}
+
+fn parseExpr(p: *Parse) Error!Node.Index {
+    return p.parseExprPrecedence(0);
+}
+
+fn expectExpr(p: *Parse) Error!Node.Index {
+    const node = try p.parseExpr();
+    if (node == 0) {
+        return p.fail(.expected_expr);
+    } else {
+        return node;
+    }
+}
+
+const Assoc = enum {
+    left,
+    none,
+};
+
+const OperInfo = struct {
+    prec: i8,
+    tag: Node.Tag,
+    assoc: Assoc = Assoc.left,
+};
+
+// A table of binary operator information. Higher precedence numbers are
+// stickier. All operators at the same precedence level should have the same
+// associativity.
+const operTable = std.enums.directEnumArrayDefault(Token.Tag, OperInfo, .{ .prec = -1, .tag = Node.Tag.root }, 0, .{
+    .keyword_or = .{ .prec = 10, .tag = .bool_or },
+
+    .keyword_and = .{ .prec = 20, .tag = .bool_and },
+
+    .equal_equal = .{ .prec = 30, .tag = .equal_equal, .assoc = Assoc.none },
+    .bang_equal = .{ .prec = 30, .tag = .bang_equal, .assoc = Assoc.none },
+    .angle_bracket_left = .{ .prec = 30, .tag = .less_than, .assoc = Assoc.none },
+    .angle_bracket_right = .{ .prec = 30, .tag = .greater_than, .assoc = Assoc.none },
+    .angle_bracket_left_equal = .{ .prec = 30, .tag = .less_or_equal, .assoc = Assoc.none },
+    .angle_bracket_right_equal = .{ .prec = 30, .tag = .greater_or_equal, .assoc = Assoc.none },
+
+    .ampersand = .{ .prec = 40, .tag = .bit_and },
+    .caret = .{ .prec = 40, .tag = .bit_xor },
+    .pipe = .{ .prec = 40, .tag = .bit_or },
+    .keyword_orelse = .{ .prec = 40, .tag = .@"orelse" },
+    .keyword_catch = .{ .prec = 40, .tag = .@"catch" },
+
+    .angle_bracket_angle_bracket_left = .{ .prec = 50, .tag = .shl },
+    .angle_bracket_angle_bracket_left_pipe = .{ .prec = 50, .tag = .shl_sat },
+    .angle_bracket_angle_bracket_right = .{ .prec = 50, .tag = .shr },
+
+    .plus = .{ .prec = 60, .tag = .add },
+    .minus = .{ .prec = 60, .tag = .sub },
+    .plus_plus = .{ .prec = 60, .tag = .array_cat },
+    .plus_percent = .{ .prec = 60, .tag = .add_wrap },
+    .minus_percent = .{ .prec = 60, .tag = .sub_wrap },
+    .plus_pipe = .{ .prec = 60, .tag = .add_sat },
+    .minus_pipe = .{ .prec = 60, .tag = .sub_sat },
+
+    .pipe_pipe = .{ .prec = 70, .tag = .merge_error_sets },
+    .asterisk = .{ .prec = 70, .tag = .mul },
+    .slash = .{ .prec = 70, .tag = .div },
+    .percent = .{ .prec = 70, .tag = .mod },
+    .asterisk_asterisk = .{ .prec = 70, .tag = .array_mult },
+    .asterisk_percent = .{ .prec = 70, .tag = .mul_wrap },
+    .asterisk_pipe = .{ .prec = 70, .tag = .mul_sat },
+});
+
+fn parseExprPrecedence(p: *Parse, min_prec: i32) Error!Node.Index {
+    assert(min_prec >= 0);
+    var node = try p.parsePrefixExpr();
+    if (node == 0) {
+        return null_node;
+    }
+
+    var banned_prec: i8 = -1;
+
+    while (true) {
+        const tok_tag = p.token_tags[p.tok_i];
+        const info = operTable[@intCast(usize, @enumToInt(tok_tag))];
+        if (info.prec < min_prec) {
+            break;
+        }
+        if (info.prec == banned_prec) {
+            return p.fail(.chained_comparison_operators);
+        }
+
+        const oper_token = p.nextToken();
+        // Special-case handling for "catch"
+        if (tok_tag == .keyword_catch) {
+            _ = try p.parsePayload();
+        }
+        const rhs = try p.parseExprPrecedence(info.prec + 1);
+        if (rhs == 0) {
+            try p.warn(.expected_expr);
+            return node;
+        }
+
+        {
+            const tok_len = tok_tag.lexeme().?.len;
+            const char_before = p.source[p.token_starts[oper_token] - 1];
+            const char_after = p.source[p.token_starts[oper_token] + tok_len];
+            if (tok_tag == .ampersand and char_after == '&') {
+                // without types we don't know if '&&' was intended as 'bitwise_and address_of', or a c-style logical_and
+                // The best the parser can do is recommend changing it to 'and' or ' & &'
+                try p.warnMsg(.{ .tag = .invalid_ampersand_ampersand, .token = oper_token });
+            } else if (std.ascii.isWhitespace(char_before) != std.ascii.isWhitespace(char_after)) {
+                try p.warnMsg(.{ .tag = .mismatched_binary_op_whitespace, .token = oper_token });
+            }
+        }
+
+        node = try p.addNode(.{
+            .tag = info.tag,
+            .main_token = oper_token,
+            .data = .{
+                .lhs = node,
+                .rhs = rhs,
+            },
+        });
+
+        if (info.assoc == Assoc.none) {
+            banned_prec = info.prec;
+        }
+    }
+
+    return node;
+}
+
+/// PrefixExpr <- PrefixOp* PrimaryExpr
+///
+/// PrefixOp
+///     <- EXCLAMATIONMARK
+///      / MINUS
+///      / TILDE
+///      / MINUSPERCENT
+///      / AMPERSAND
+///      / KEYWORD_try
+///      / KEYWORD_await
+fn parsePrefixExpr(p: *Parse) Error!Node.Index {
+    const tag: Node.Tag = switch (p.token_tags[p.tok_i]) {
+        .bang => .bool_not,
+        .minus => .negation,
+        .tilde => .bit_not,
+        .minus_percent => .negation_wrap,
+        .ampersand => .address_of,
+        .keyword_try => .@"try",
+        .keyword_await => .@"await",
+        else => return p.parsePrimaryExpr(),
+    };
+    return p.addNode(.{
+        .tag = tag,
+        .main_token = p.nextToken(),
+        .data = .{
+            .lhs = try p.expectPrefixExpr(),
+            .rhs = undefined,
+        },
+    });
+}
+
+fn expectPrefixExpr(p: *Parse) Error!Node.Index {
+    const node = try p.parsePrefixExpr();
+    if (node == 0) {
+        return p.fail(.expected_prefix_expr);
+    }
+    return node;
+}
+
+/// TypeExpr <- PrefixTypeOp* ErrorUnionExpr
+///
+/// PrefixTypeOp
+///     <- QUESTIONMARK
+///      / KEYWORD_anyframe MINUSRARROW
+///      / SliceTypeStart (ByteAlign / AddrSpace / KEYWORD_const / KEYWORD_volatile / KEYWORD_allowzero)*
+///      / PtrTypeStart (AddrSpace / KEYWORD_align LPAREN Expr (COLON Expr COLON Expr)? RPAREN / KEYWORD_const / KEYWORD_volatile / KEYWORD_allowzero)*
+///      / ArrayTypeStart
+///
+/// SliceTypeStart <- LBRACKET (COLON Expr)? RBRACKET
+///
+/// PtrTypeStart
+///     <- ASTERISK
+///      / ASTERISK2
+///      / LBRACKET ASTERISK (LETTERC / COLON Expr)? RBRACKET
+///
+/// ArrayTypeStart <- LBRACKET Expr (COLON Expr)? RBRACKET
+fn parseTypeExpr(p: *Parse) Error!Node.Index {
+    switch (p.token_tags[p.tok_i]) {
+        .question_mark => return p.addNode(.{
+            .tag = .optional_type,
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = try p.expectTypeExpr(),
+                .rhs = undefined,
+            },
+        }),
+        .keyword_anyframe => switch (p.token_tags[p.tok_i + 1]) {
+            .arrow => return p.addNode(.{
+                .tag = .anyframe_type,
+                .main_token = p.nextToken(),
+                .data = .{
+                    .lhs = p.nextToken(),
+                    .rhs = try p.expectTypeExpr(),
+                },
+            }),
+            else => return p.parseErrorUnionExpr(),
+        },
+        .asterisk => {
+            const asterisk = p.nextToken();
+            const mods = try p.parsePtrModifiers();
+            const elem_type = try p.expectTypeExpr();
+            if (mods.bit_range_start != 0) {
+                return p.addNode(.{
+                    .tag = .ptr_type_bit_range,
+                    .main_token = asterisk,
+                    .data = .{
+                        .lhs = try p.addExtra(Node.PtrTypeBitRange{
+                            .sentinel = 0,
+                            .align_node = mods.align_node,
+                            .addrspace_node = mods.addrspace_node,
+                            .bit_range_start = mods.bit_range_start,
+                            .bit_range_end = mods.bit_range_end,
+                        }),
+                        .rhs = elem_type,
+                    },
+                });
+            } else if (mods.addrspace_node != 0) {
+                return p.addNode(.{
+                    .tag = .ptr_type,
+                    .main_token = asterisk,
+                    .data = .{
+                        .lhs = try p.addExtra(Node.PtrType{
+                            .sentinel = 0,
+                            .align_node = mods.align_node,
+                            .addrspace_node = mods.addrspace_node,
+                        }),
+                        .rhs = elem_type,
+                    },
+                });
+            } else {
+                return p.addNode(.{
+                    .tag = .ptr_type_aligned,
+                    .main_token = asterisk,
+                    .data = .{
+                        .lhs = mods.align_node,
+                        .rhs = elem_type,
+                    },
+                });
+            }
+        },
+        .asterisk_asterisk => {
+            const asterisk = p.nextToken();
+            const mods = try p.parsePtrModifiers();
+            const elem_type = try p.expectTypeExpr();
+            const inner: Node.Index = inner: {
+                if (mods.bit_range_start != 0) {
+                    break :inner try p.addNode(.{
+                        .tag = .ptr_type_bit_range,
+                        .main_token = asterisk,
+                        .data = .{
+                            .lhs = try p.addExtra(Node.PtrTypeBitRange{
+                                .sentinel = 0,
+                                .align_node = mods.align_node,
+                                .addrspace_node = mods.addrspace_node,
+                                .bit_range_start = mods.bit_range_start,
+                                .bit_range_end = mods.bit_range_end,
+                            }),
+                            .rhs = elem_type,
+                        },
+                    });
+                } else if (mods.addrspace_node != 0) {
+                    break :inner try p.addNode(.{
+                        .tag = .ptr_type,
+                        .main_token = asterisk,
+                        .data = .{
+                            .lhs = try p.addExtra(Node.PtrType{
+                                .sentinel = 0,
+                                .align_node = mods.align_node,
+                                .addrspace_node = mods.addrspace_node,
+                            }),
+                            .rhs = elem_type,
+                        },
+                    });
+                } else {
+                    break :inner try p.addNode(.{
+                        .tag = .ptr_type_aligned,
+                        .main_token = asterisk,
+                        .data = .{
+                            .lhs = mods.align_node,
+                            .rhs = elem_type,
+                        },
+                    });
+                }
+            };
+            return p.addNode(.{
+                .tag = .ptr_type_aligned,
+                .main_token = asterisk,
+                .data = .{
+                    .lhs = 0,
+                    .rhs = inner,
+                },
+            });
+        },
+        .l_bracket => switch (p.token_tags[p.tok_i + 1]) {
+            .asterisk => {
+                _ = p.nextToken();
+                const asterisk = p.nextToken();
+                var sentinel: Node.Index = 0;
+                if (p.eatToken(.identifier)) |ident| {
+                    const ident_slice = p.source[p.token_starts[ident]..p.token_starts[ident + 1]];
+                    if (!std.mem.eql(u8, std.mem.trimRight(u8, ident_slice, &std.ascii.whitespace), "c")) {
+                        p.tok_i -= 1;
+                    }
+                } else if (p.eatToken(.colon)) |_| {
+                    sentinel = try p.expectExpr();
+                }
+                _ = try p.expectToken(.r_bracket);
+                const mods = try p.parsePtrModifiers();
+                const elem_type = try p.expectTypeExpr();
+                if (mods.bit_range_start == 0) {
+                    if (sentinel == 0 and mods.addrspace_node == 0) {
+                        return p.addNode(.{
+                            .tag = .ptr_type_aligned,
+                            .main_token = asterisk,
+                            .data = .{
+                                .lhs = mods.align_node,
+                                .rhs = elem_type,
+                            },
+                        });
+                    } else if (mods.align_node == 0 and mods.addrspace_node == 0) {
+                        return p.addNode(.{
+                            .tag = .ptr_type_sentinel,
+                            .main_token = asterisk,
+                            .data = .{
+                                .lhs = sentinel,
+                                .rhs = elem_type,
+                            },
+                        });
+                    } else {
+                        return p.addNode(.{
+                            .tag = .ptr_type,
+                            .main_token = asterisk,
+                            .data = .{
+                                .lhs = try p.addExtra(Node.PtrType{
+                                    .sentinel = sentinel,
+                                    .align_node = mods.align_node,
+                                    .addrspace_node = mods.addrspace_node,
+                                }),
+                                .rhs = elem_type,
+                            },
+                        });
+                    }
+                } else {
+                    return p.addNode(.{
+                        .tag = .ptr_type_bit_range,
+                        .main_token = asterisk,
+                        .data = .{
+                            .lhs = try p.addExtra(Node.PtrTypeBitRange{
+                                .sentinel = sentinel,
+                                .align_node = mods.align_node,
+                                .addrspace_node = mods.addrspace_node,
+                                .bit_range_start = mods.bit_range_start,
+                                .bit_range_end = mods.bit_range_end,
+                            }),
+                            .rhs = elem_type,
+                        },
+                    });
+                }
+            },
+            else => {
+                const lbracket = p.nextToken();
+                const len_expr = try p.parseExpr();
+                const sentinel: Node.Index = if (p.eatToken(.colon)) |_|
+                    try p.expectExpr()
+                else
+                    0;
+                _ = try p.expectToken(.r_bracket);
+                if (len_expr == 0) {
+                    const mods = try p.parsePtrModifiers();
+                    const elem_type = try p.expectTypeExpr();
+                    if (mods.bit_range_start != 0) {
+                        try p.warnMsg(.{
+                            .tag = .invalid_bit_range,
+                            .token = p.nodes.items(.main_token)[mods.bit_range_start],
+                        });
+                    }
+                    if (sentinel == 0 and mods.addrspace_node == 0) {
+                        return p.addNode(.{
+                            .tag = .ptr_type_aligned,
+                            .main_token = lbracket,
+                            .data = .{
+                                .lhs = mods.align_node,
+                                .rhs = elem_type,
+                            },
+                        });
+                    } else if (mods.align_node == 0 and mods.addrspace_node == 0) {
+                        return p.addNode(.{
+                            .tag = .ptr_type_sentinel,
+                            .main_token = lbracket,
+                            .data = .{
+                                .lhs = sentinel,
+                                .rhs = elem_type,
+                            },
+                        });
+                    } else {
+                        return p.addNode(.{
+                            .tag = .ptr_type,
+                            .main_token = lbracket,
+                            .data = .{
+                                .lhs = try p.addExtra(Node.PtrType{
+                                    .sentinel = sentinel,
+                                    .align_node = mods.align_node,
+                                    .addrspace_node = mods.addrspace_node,
+                                }),
+                                .rhs = elem_type,
+                            },
+                        });
+                    }
+                } else {
+                    switch (p.token_tags[p.tok_i]) {
+                        .keyword_align,
+                        .keyword_const,
+                        .keyword_volatile,
+                        .keyword_allowzero,
+                        .keyword_addrspace,
+                        => return p.fail(.ptr_mod_on_array_child_type),
+                        else => {},
+                    }
+                    const elem_type = try p.expectTypeExpr();
+                    if (sentinel == 0) {
+                        return p.addNode(.{
+                            .tag = .array_type,
+                            .main_token = lbracket,
+                            .data = .{
+                                .lhs = len_expr,
+                                .rhs = elem_type,
+                            },
+                        });
+                    } else {
+                        return p.addNode(.{
+                            .tag = .array_type_sentinel,
+                            .main_token = lbracket,
+                            .data = .{
+                                .lhs = len_expr,
+                                .rhs = try p.addExtra(.{
+                                    .elem_type = elem_type,
+                                    .sentinel = sentinel,
+                                }),
+                            },
+                        });
+                    }
+                }
+            },
+        },
+        else => return p.parseErrorUnionExpr(),
+    }
+}
+
+fn expectTypeExpr(p: *Parse) Error!Node.Index {
+    const node = try p.parseTypeExpr();
+    if (node == 0) {
+        return p.fail(.expected_type_expr);
+    }
+    return node;
+}
+
+/// PrimaryExpr
+///     <- AsmExpr
+///      / IfExpr
+///      / KEYWORD_break BreakLabel? Expr?
+///      / KEYWORD_comptime Expr
+///      / KEYWORD_nosuspend Expr
+///      / KEYWORD_continue BreakLabel?
+///      / KEYWORD_resume Expr
+///      / KEYWORD_return Expr?
+///      / BlockLabel? LoopExpr
+///      / Block
+///      / CurlySuffixExpr
+fn parsePrimaryExpr(p: *Parse) !Node.Index {
+    switch (p.token_tags[p.tok_i]) {
+        .keyword_asm => return p.expectAsmExpr(),
+        .keyword_if => return p.parseIfExpr(),
+        .keyword_break => {
+            p.tok_i += 1;
+            return p.addNode(.{
+                .tag = .@"break",
+                .main_token = p.tok_i - 1,
+                .data = .{
+                    .lhs = try p.parseBreakLabel(),
+                    .rhs = try p.parseExpr(),
+                },
+            });
+        },
+        .keyword_continue => {
+            p.tok_i += 1;
+            return p.addNode(.{
+                .tag = .@"continue",
+                .main_token = p.tok_i - 1,
+                .data = .{
+                    .lhs = try p.parseBreakLabel(),
+                    .rhs = undefined,
+                },
+            });
+        },
+        .keyword_comptime => {
+            p.tok_i += 1;
+            return p.addNode(.{
+                .tag = .@"comptime",
+                .main_token = p.tok_i - 1,
+                .data = .{
+                    .lhs = try p.expectExpr(),
+                    .rhs = undefined,
+                },
+            });
+        },
+        .keyword_nosuspend => {
+            p.tok_i += 1;
+            return p.addNode(.{
+                .tag = .@"nosuspend",
+                .main_token = p.tok_i - 1,
+                .data = .{
+                    .lhs = try p.expectExpr(),
+                    .rhs = undefined,
+                },
+            });
+        },
+        .keyword_resume => {
+            p.tok_i += 1;
+            return p.addNode(.{
+                .tag = .@"resume",
+                .main_token = p.tok_i - 1,
+                .data = .{
+                    .lhs = try p.expectExpr(),
+                    .rhs = undefined,
+                },
+            });
+        },
+        .keyword_return => {
+            p.tok_i += 1;
+            return p.addNode(.{
+                .tag = .@"return",
+                .main_token = p.tok_i - 1,
+                .data = .{
+                    .lhs = try p.parseExpr(),
+                    .rhs = undefined,
+                },
+            });
+        },
+        .identifier => {
+            if (p.token_tags[p.tok_i + 1] == .colon) {
+                switch (p.token_tags[p.tok_i + 2]) {
+                    .keyword_inline => {
+                        p.tok_i += 3;
+                        switch (p.token_tags[p.tok_i]) {
+                            .keyword_for => return p.parseForExpr(),
+                            .keyword_while => return p.parseWhileExpr(),
+                            else => return p.fail(.expected_inlinable),
+                        }
+                    },
+                    .keyword_for => {
+                        p.tok_i += 2;
+                        return p.parseForExpr();
+                    },
+                    .keyword_while => {
+                        p.tok_i += 2;
+                        return p.parseWhileExpr();
+                    },
+                    .l_brace => {
+                        p.tok_i += 2;
+                        return p.parseBlock();
+                    },
+                    else => return p.parseCurlySuffixExpr(),
+                }
+            } else {
+                return p.parseCurlySuffixExpr();
+            }
+        },
+        .keyword_inline => {
+            p.tok_i += 1;
+            switch (p.token_tags[p.tok_i]) {
+                .keyword_for => return p.parseForExpr(),
+                .keyword_while => return p.parseWhileExpr(),
+                else => return p.fail(.expected_inlinable),
+            }
+        },
+        .keyword_for => return p.parseForExpr(),
+        .keyword_while => return p.parseWhileExpr(),
+        .l_brace => return p.parseBlock(),
+        else => return p.parseCurlySuffixExpr(),
+    }
+}
+
+/// IfExpr <- IfPrefix Expr (KEYWORD_else Payload? Expr)?
+fn parseIfExpr(p: *Parse) !Node.Index {
+    return p.parseIf(expectExpr);
+}
+
+/// Block <- LBRACE Statement* RBRACE
+fn parseBlock(p: *Parse) !Node.Index {
+    const lbrace = p.eatToken(.l_brace) orelse return null_node;
+    const scratch_top = p.scratch.items.len;
+    defer p.scratch.shrinkRetainingCapacity(scratch_top);
+    while (true) {
+        if (p.token_tags[p.tok_i] == .r_brace) break;
+        const statement = try p.expectStatementRecoverable();
+        if (statement == 0) break;
+        try p.scratch.append(p.gpa, statement);
+    }
+    _ = try p.expectToken(.r_brace);
+    const semicolon = (p.token_tags[p.tok_i - 2] == .semicolon);
+    const statements = p.scratch.items[scratch_top..];
+    switch (statements.len) {
+        0 => return p.addNode(.{
+            .tag = .block_two,
+            .main_token = lbrace,
+            .data = .{
+                .lhs = 0,
+                .rhs = 0,
+            },
+        }),
+        1 => return p.addNode(.{
+            .tag = if (semicolon) .block_two_semicolon else .block_two,
+            .main_token = lbrace,
+            .data = .{
+                .lhs = statements[0],
+                .rhs = 0,
+            },
+        }),
+        2 => return p.addNode(.{
+            .tag = if (semicolon) .block_two_semicolon else .block_two,
+            .main_token = lbrace,
+            .data = .{
+                .lhs = statements[0],
+                .rhs = statements[1],
+            },
+        }),
+        else => {
+            const span = try p.listToSpan(statements);
+            return p.addNode(.{
+                .tag = if (semicolon) .block_semicolon else .block,
+                .main_token = lbrace,
+                .data = .{
+                    .lhs = span.start,
+                    .rhs = span.end,
+                },
+            });
+        },
+    }
+}
+
+/// ForPrefix <- KEYWORD_for LPAREN Expr RPAREN PtrIndexPayload
+///
+/// ForExpr <- ForPrefix Expr (KEYWORD_else Expr)?
+fn parseForExpr(p: *Parse) !Node.Index {
+    const for_token = p.eatToken(.keyword_for) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const array_expr = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    const found_payload = try p.parsePtrIndexPayload();
+    if (found_payload == 0) try p.warn(.expected_loop_payload);
+
+    const then_expr = try p.expectExpr();
+    _ = p.eatToken(.keyword_else) orelse {
+        return p.addNode(.{
+            .tag = .for_simple,
+            .main_token = for_token,
+            .data = .{
+                .lhs = array_expr,
+                .rhs = then_expr,
+            },
+        });
+    };
+    const else_expr = try p.expectExpr();
+    return p.addNode(.{
+        .tag = .@"for",
+        .main_token = for_token,
+        .data = .{
+            .lhs = array_expr,
+            .rhs = try p.addExtra(Node.If{
+                .then_expr = then_expr,
+                .else_expr = else_expr,
+            }),
+        },
+    });
+}
+
+/// WhilePrefix <- KEYWORD_while LPAREN Expr RPAREN PtrPayload? WhileContinueExpr?
+///
+/// WhileExpr <- WhilePrefix Expr (KEYWORD_else Payload? Expr)?
+fn parseWhileExpr(p: *Parse) !Node.Index {
+    const while_token = p.eatToken(.keyword_while) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const condition = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    _ = try p.parsePtrPayload();
+    const cont_expr = try p.parseWhileContinueExpr();
+
+    const then_expr = try p.expectExpr();
+    _ = p.eatToken(.keyword_else) orelse {
+        if (cont_expr == 0) {
+            return p.addNode(.{
+                .tag = .while_simple,
+                .main_token = while_token,
+                .data = .{
+                    .lhs = condition,
+                    .rhs = then_expr,
+                },
+            });
+        } else {
+            return p.addNode(.{
+                .tag = .while_cont,
+                .main_token = while_token,
+                .data = .{
+                    .lhs = condition,
+                    .rhs = try p.addExtra(Node.WhileCont{
+                        .cont_expr = cont_expr,
+                        .then_expr = then_expr,
+                    }),
+                },
+            });
+        }
+    };
+    _ = try p.parsePayload();
+    const else_expr = try p.expectExpr();
+    return p.addNode(.{
+        .tag = .@"while",
+        .main_token = while_token,
+        .data = .{
+            .lhs = condition,
+            .rhs = try p.addExtra(Node.While{
+                .cont_expr = cont_expr,
+                .then_expr = then_expr,
+                .else_expr = else_expr,
+            }),
+        },
+    });
+}
+
+/// CurlySuffixExpr <- TypeExpr InitList?
+///
+/// InitList
+///     <- LBRACE FieldInit (COMMA FieldInit)* COMMA? RBRACE
+///      / LBRACE Expr (COMMA Expr)* COMMA? RBRACE
+///      / LBRACE RBRACE
+fn parseCurlySuffixExpr(p: *Parse) !Node.Index {
+    const lhs = try p.parseTypeExpr();
+    if (lhs == 0) return null_node;
+    const lbrace = p.eatToken(.l_brace) orelse return lhs;
+
+    // If there are 0 or 1 items, we can use ArrayInitOne/StructInitOne;
+    // otherwise we use the full ArrayInit/StructInit.
+
+    const scratch_top = p.scratch.items.len;
+    defer p.scratch.shrinkRetainingCapacity(scratch_top);
+    const field_init = try p.parseFieldInit();
+    if (field_init != 0) {
+        try p.scratch.append(p.gpa, field_init);
+        while (true) {
+            switch (p.token_tags[p.tok_i]) {
+                .comma => p.tok_i += 1,
+                .r_brace => {
+                    p.tok_i += 1;
+                    break;
+                },
+                .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
+                // Likely just a missing comma; give error but continue parsing.
+                else => try p.warn(.expected_comma_after_initializer),
+            }
+            if (p.eatToken(.r_brace)) |_| break;
+            const next = try p.expectFieldInit();
+            try p.scratch.append(p.gpa, next);
+        }
+        const comma = (p.token_tags[p.tok_i - 2] == .comma);
+        const inits = p.scratch.items[scratch_top..];
+        switch (inits.len) {
+            0 => unreachable,
+            1 => return p.addNode(.{
+                .tag = if (comma) .struct_init_one_comma else .struct_init_one,
+                .main_token = lbrace,
+                .data = .{
+                    .lhs = lhs,
+                    .rhs = inits[0],
+                },
+            }),
+            else => return p.addNode(.{
+                .tag = if (comma) .struct_init_comma else .struct_init,
+                .main_token = lbrace,
+                .data = .{
+                    .lhs = lhs,
+                    .rhs = try p.addExtra(try p.listToSpan(inits)),
+                },
+            }),
+        }
+    }
+
+    while (true) {
+        if (p.eatToken(.r_brace)) |_| break;
+        const elem_init = try p.expectExpr();
+        try p.scratch.append(p.gpa, elem_init);
+        switch (p.token_tags[p.tok_i]) {
+            .comma => p.tok_i += 1,
+            .r_brace => {
+                p.tok_i += 1;
+                break;
+            },
+            .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
+            // Likely just a missing comma; give error but continue parsing.
+            else => try p.warn(.expected_comma_after_initializer),
+        }
+    }
+    const comma = (p.token_tags[p.tok_i - 2] == .comma);
+    const inits = p.scratch.items[scratch_top..];
+    switch (inits.len) {
+        0 => return p.addNode(.{
+            .tag = .struct_init_one,
+            .main_token = lbrace,
+            .data = .{
+                .lhs = lhs,
+                .rhs = 0,
+            },
+        }),
+        1 => return p.addNode(.{
+            .tag = if (comma) .array_init_one_comma else .array_init_one,
+            .main_token = lbrace,
+            .data = .{
+                .lhs = lhs,
+                .rhs = inits[0],
+            },
+        }),
+        else => return p.addNode(.{
+            .tag = if (comma) .array_init_comma else .array_init,
+            .main_token = lbrace,
+            .data = .{
+                .lhs = lhs,
+                .rhs = try p.addExtra(try p.listToSpan(inits)),
+            },
+        }),
+    }
+}
+
+/// ErrorUnionExpr <- SuffixExpr (EXCLAMATIONMARK TypeExpr)?
+fn parseErrorUnionExpr(p: *Parse) !Node.Index {
+    const suffix_expr = try p.parseSuffixExpr();
+    if (suffix_expr == 0) return null_node;
+    const bang = p.eatToken(.bang) orelse return suffix_expr;
+    return p.addNode(.{
+        .tag = .error_union,
+        .main_token = bang,
+        .data = .{
+            .lhs = suffix_expr,
+            .rhs = try p.expectTypeExpr(),
+        },
+    });
+}
+
+/// SuffixExpr
+///     <- KEYWORD_async PrimaryTypeExpr SuffixOp* FnCallArguments
+///      / PrimaryTypeExpr (SuffixOp / FnCallArguments)*
+///
+/// FnCallArguments <- LPAREN ExprList RPAREN
+///
+/// ExprList <- (Expr COMMA)* Expr?
+fn parseSuffixExpr(p: *Parse) !Node.Index {
+    if (p.eatToken(.keyword_async)) |_| {
+        var res = try p.expectPrimaryTypeExpr();
+        while (true) {
+            const node = try p.parseSuffixOp(res);
+            if (node == 0) break;
+            res = node;
+        }
+        const lparen = p.eatToken(.l_paren) orelse {
+            try p.warn(.expected_param_list);
+            return res;
+        };
+        const scratch_top = p.scratch.items.len;
+        defer p.scratch.shrinkRetainingCapacity(scratch_top);
+        while (true) {
+            if (p.eatToken(.r_paren)) |_| break;
+            const param = try p.expectExpr();
+            try p.scratch.append(p.gpa, param);
+            switch (p.token_tags[p.tok_i]) {
+                .comma => p.tok_i += 1,
+                .r_paren => {
+                    p.tok_i += 1;
+                    break;
+                },
+                .colon, .r_brace, .r_bracket => return p.failExpected(.r_paren),
+                // Likely just a missing comma; give error but continue parsing.
+                else => try p.warn(.expected_comma_after_arg),
+            }
+        }
+        const comma = (p.token_tags[p.tok_i - 2] == .comma);
+        const params = p.scratch.items[scratch_top..];
+        switch (params.len) {
+            0 => return p.addNode(.{
+                .tag = if (comma) .async_call_one_comma else .async_call_one,
+                .main_token = lparen,
+                .data = .{
+                    .lhs = res,
+                    .rhs = 0,
+                },
+            }),
+            1 => return p.addNode(.{
+                .tag = if (comma) .async_call_one_comma else .async_call_one,
+                .main_token = lparen,
+                .data = .{
+                    .lhs = res,
+                    .rhs = params[0],
+                },
+            }),
+            else => return p.addNode(.{
+                .tag = if (comma) .async_call_comma else .async_call,
+                .main_token = lparen,
+                .data = .{
+                    .lhs = res,
+                    .rhs = try p.addExtra(try p.listToSpan(params)),
+                },
+            }),
+        }
+    }
+
+    var res = try p.parsePrimaryTypeExpr();
+    if (res == 0) return res;
+    while (true) {
+        const suffix_op = try p.parseSuffixOp(res);
+        if (suffix_op != 0) {
+            res = suffix_op;
+            continue;
+        }
+        const lparen = p.eatToken(.l_paren) orelse return res;
+        const scratch_top = p.scratch.items.len;
+        defer p.scratch.shrinkRetainingCapacity(scratch_top);
+        while (true) {
+            if (p.eatToken(.r_paren)) |_| break;
+            const param = try p.expectExpr();
+            try p.scratch.append(p.gpa, param);
+            switch (p.token_tags[p.tok_i]) {
+                .comma => p.tok_i += 1,
+                .r_paren => {
+                    p.tok_i += 1;
+                    break;
+                },
+                .colon, .r_brace, .r_bracket => return p.failExpected(.r_paren),
+                // Likely just a missing comma; give error but continue parsing.
+                else => try p.warn(.expected_comma_after_arg),
+            }
+        }
+        const comma = (p.token_tags[p.tok_i - 2] == .comma);
+        const params = p.scratch.items[scratch_top..];
+        res = switch (params.len) {
+            0 => try p.addNode(.{
+                .tag = if (comma) .call_one_comma else .call_one,
+                .main_token = lparen,
+                .data = .{
+                    .lhs = res,
+                    .rhs = 0,
+                },
+            }),
+            1 => try p.addNode(.{
+                .tag = if (comma) .call_one_comma else .call_one,
+                .main_token = lparen,
+                .data = .{
+                    .lhs = res,
+                    .rhs = params[0],
+                },
+            }),
+            else => try p.addNode(.{
+                .tag = if (comma) .call_comma else .call,
+                .main_token = lparen,
+                .data = .{
+                    .lhs = res,
+                    .rhs = try p.addExtra(try p.listToSpan(params)),
+                },
+            }),
+        };
+    }
+}
+
+/// PrimaryTypeExpr
+///     <- BUILTINIDENTIFIER FnCallArguments
+///      / CHAR_LITERAL
+///      / ContainerDecl
+///      / DOT IDENTIFIER
+///      / DOT InitList
+///      / ErrorSetDecl
+///      / FLOAT
+///      / FnProto
+///      / GroupedExpr
+///      / LabeledTypeExpr
+///      / IDENTIFIER
+///      / IfTypeExpr
+///      / INTEGER
+///      / KEYWORD_comptime TypeExpr
+///      / KEYWORD_error DOT IDENTIFIER
+///      / KEYWORD_anyframe
+///      / KEYWORD_unreachable
+///      / STRINGLITERAL
+///      / SwitchExpr
+///
+/// ContainerDecl <- (KEYWORD_extern / KEYWORD_packed)? ContainerDeclAuto
+///
+/// ContainerDeclAuto <- ContainerDeclType LBRACE container_doc_comment? ContainerMembers RBRACE
+///
+/// InitList
+///     <- LBRACE FieldInit (COMMA FieldInit)* COMMA? RBRACE
+///      / LBRACE Expr (COMMA Expr)* COMMA? RBRACE
+///      / LBRACE RBRACE
+///
+/// ErrorSetDecl <- KEYWORD_error LBRACE IdentifierList RBRACE
+///
+/// GroupedExpr <- LPAREN Expr RPAREN
+///
+/// IfTypeExpr <- IfPrefix TypeExpr (KEYWORD_else Payload? TypeExpr)?
+///
+/// LabeledTypeExpr
+///     <- BlockLabel Block
+///      / BlockLabel? LoopTypeExpr
+///
+/// LoopTypeExpr <- KEYWORD_inline? (ForTypeExpr / WhileTypeExpr)
+fn parsePrimaryTypeExpr(p: *Parse) !Node.Index {
+    switch (p.token_tags[p.tok_i]) {
+        .char_literal => return p.addNode(.{
+            .tag = .char_literal,
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = undefined,
+                .rhs = undefined,
+            },
+        }),
+        .number_literal => return p.addNode(.{
+            .tag = .number_literal,
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = undefined,
+                .rhs = undefined,
+            },
+        }),
+        .keyword_unreachable => return p.addNode(.{
+            .tag = .unreachable_literal,
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = undefined,
+                .rhs = undefined,
+            },
+        }),
+        .keyword_anyframe => return p.addNode(.{
+            .tag = .anyframe_literal,
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = undefined,
+                .rhs = undefined,
+            },
+        }),
+        .string_literal => {
+            const main_token = p.nextToken();
+            return p.addNode(.{
+                .tag = .string_literal,
+                .main_token = main_token,
+                .data = .{
+                    .lhs = undefined,
+                    .rhs = undefined,
+                },
+            });
+        },
+
+        .builtin => return p.parseBuiltinCall(),
+        .keyword_fn => return p.parseFnProto(),
+        .keyword_if => return p.parseIf(expectTypeExpr),
+        .keyword_switch => return p.expectSwitchExpr(),
+
+        .keyword_extern,
+        .keyword_packed,
+        => {
+            p.tok_i += 1;
+            return p.parseContainerDeclAuto();
+        },
+
+        .keyword_struct,
+        .keyword_opaque,
+        .keyword_enum,
+        .keyword_union,
+        => return p.parseContainerDeclAuto(),
+
+        .keyword_comptime => return p.addNode(.{
+            .tag = .@"comptime",
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = try p.expectTypeExpr(),
+                .rhs = undefined,
+            },
+        }),
+        .multiline_string_literal_line => {
+            const first_line = p.nextToken();
+            while (p.token_tags[p.tok_i] == .multiline_string_literal_line) {
+                p.tok_i += 1;
+            }
+            return p.addNode(.{
+                .tag = .multiline_string_literal,
+                .main_token = first_line,
+                .data = .{
+                    .lhs = first_line,
+                    .rhs = p.tok_i - 1,
+                },
+            });
+        },
+        .identifier => switch (p.token_tags[p.tok_i + 1]) {
+            .colon => switch (p.token_tags[p.tok_i + 2]) {
+                .keyword_inline => {
+                    p.tok_i += 3;
+                    switch (p.token_tags[p.tok_i]) {
+                        .keyword_for => return p.parseForTypeExpr(),
+                        .keyword_while => return p.parseWhileTypeExpr(),
+                        else => return p.fail(.expected_inlinable),
+                    }
+                },
+                .keyword_for => {
+                    p.tok_i += 2;
+                    return p.parseForTypeExpr();
+                },
+                .keyword_while => {
+                    p.tok_i += 2;
+                    return p.parseWhileTypeExpr();
+                },
+                .l_brace => {
+                    p.tok_i += 2;
+                    return p.parseBlock();
+                },
+                else => return p.addNode(.{
+                    .tag = .identifier,
+                    .main_token = p.nextToken(),
+                    .data = .{
+                        .lhs = undefined,
+                        .rhs = undefined,
+                    },
+                }),
+            },
+            else => return p.addNode(.{
+                .tag = .identifier,
+                .main_token = p.nextToken(),
+                .data = .{
+                    .lhs = undefined,
+                    .rhs = undefined,
+                },
+            }),
+        },
+        .keyword_inline => {
+            p.tok_i += 1;
+            switch (p.token_tags[p.tok_i]) {
+                .keyword_for => return p.parseForTypeExpr(),
+                .keyword_while => return p.parseWhileTypeExpr(),
+                else => return p.fail(.expected_inlinable),
+            }
+        },
+        .keyword_for => return p.parseForTypeExpr(),
+        .keyword_while => return p.parseWhileTypeExpr(),
+        .period => switch (p.token_tags[p.tok_i + 1]) {
+            .identifier => return p.addNode(.{
+                .tag = .enum_literal,
+                .data = .{
+                    .lhs = p.nextToken(), // dot
+                    .rhs = undefined,
+                },
+                .main_token = p.nextToken(), // identifier
+            }),
+            .l_brace => {
+                const lbrace = p.tok_i + 1;
+                p.tok_i = lbrace + 1;
+
+                // If there are 0, 1, or 2 items, we can use ArrayInitDotTwo/StructInitDotTwo;
+                // otherwise we use the full ArrayInitDot/StructInitDot.
+
+                const scratch_top = p.scratch.items.len;
+                defer p.scratch.shrinkRetainingCapacity(scratch_top);
+                const field_init = try p.parseFieldInit();
+                if (field_init != 0) {
+                    try p.scratch.append(p.gpa, field_init);
+                    while (true) {
+                        switch (p.token_tags[p.tok_i]) {
+                            .comma => p.tok_i += 1,
+                            .r_brace => {
+                                p.tok_i += 1;
+                                break;
+                            },
+                            .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
+                            // Likely just a missing comma; give error but continue parsing.
+                            else => try p.warn(.expected_comma_after_initializer),
+                        }
+                        if (p.eatToken(.r_brace)) |_| break;
+                        const next = try p.expectFieldInit();
+                        try p.scratch.append(p.gpa, next);
+                    }
+                    const comma = (p.token_tags[p.tok_i - 2] == .comma);
+                    const inits = p.scratch.items[scratch_top..];
+                    switch (inits.len) {
+                        0 => unreachable,
+                        1 => return p.addNode(.{
+                            .tag = if (comma) .struct_init_dot_two_comma else .struct_init_dot_two,
+                            .main_token = lbrace,
+                            .data = .{
+                                .lhs = inits[0],
+                                .rhs = 0,
+                            },
+                        }),
+                        2 => return p.addNode(.{
+                            .tag = if (comma) .struct_init_dot_two_comma else .struct_init_dot_two,
+                            .main_token = lbrace,
+                            .data = .{
+                                .lhs = inits[0],
+                                .rhs = inits[1],
+                            },
+                        }),
+                        else => {
+                            const span = try p.listToSpan(inits);
+                            return p.addNode(.{
+                                .tag = if (comma) .struct_init_dot_comma else .struct_init_dot,
+                                .main_token = lbrace,
+                                .data = .{
+                                    .lhs = span.start,
+                                    .rhs = span.end,
+                                },
+                            });
+                        },
+                    }
+                }
+
+                while (true) {
+                    if (p.eatToken(.r_brace)) |_| break;
+                    const elem_init = try p.expectExpr();
+                    try p.scratch.append(p.gpa, elem_init);
+                    switch (p.token_tags[p.tok_i]) {
+                        .comma => p.tok_i += 1,
+                        .r_brace => {
+                            p.tok_i += 1;
+                            break;
+                        },
+                        .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
+                        // Likely just a missing comma; give error but continue parsing.
+                        else => try p.warn(.expected_comma_after_initializer),
+                    }
+                }
+                const comma = (p.token_tags[p.tok_i - 2] == .comma);
+                const inits = p.scratch.items[scratch_top..];
+                switch (inits.len) {
+                    0 => return p.addNode(.{
+                        .tag = .struct_init_dot_two,
+                        .main_token = lbrace,
+                        .data = .{
+                            .lhs = 0,
+                            .rhs = 0,
+                        },
+                    }),
+                    1 => return p.addNode(.{
+                        .tag = if (comma) .array_init_dot_two_comma else .array_init_dot_two,
+                        .main_token = lbrace,
+                        .data = .{
+                            .lhs = inits[0],
+                            .rhs = 0,
+                        },
+                    }),
+                    2 => return p.addNode(.{
+                        .tag = if (comma) .array_init_dot_two_comma else .array_init_dot_two,
+                        .main_token = lbrace,
+                        .data = .{
+                            .lhs = inits[0],
+                            .rhs = inits[1],
+                        },
+                    }),
+                    else => {
+                        const span = try p.listToSpan(inits);
+                        return p.addNode(.{
+                            .tag = if (comma) .array_init_dot_comma else .array_init_dot,
+                            .main_token = lbrace,
+                            .data = .{
+                                .lhs = span.start,
+                                .rhs = span.end,
+                            },
+                        });
+                    },
+                }
+            },
+            else => return null_node,
+        },
+        .keyword_error => switch (p.token_tags[p.tok_i + 1]) {
+            .l_brace => {
+                const error_token = p.tok_i;
+                p.tok_i += 2;
+                while (true) {
+                    if (p.eatToken(.r_brace)) |_| break;
+                    _ = try p.eatDocComments();
+                    _ = try p.expectToken(.identifier);
+                    switch (p.token_tags[p.tok_i]) {
+                        .comma => p.tok_i += 1,
+                        .r_brace => {
+                            p.tok_i += 1;
+                            break;
+                        },
+                        .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
+                        // Likely just a missing comma; give error but continue parsing.
+                        else => try p.warn(.expected_comma_after_field),
+                    }
+                }
+                return p.addNode(.{
+                    .tag = .error_set_decl,
+                    .main_token = error_token,
+                    .data = .{
+                        .lhs = undefined,
+                        .rhs = p.tok_i - 1, // rbrace
+                    },
+                });
+            },
+            else => {
+                const main_token = p.nextToken();
+                const period = p.eatToken(.period);
+                if (period == null) try p.warnExpected(.period);
+                const identifier = p.eatToken(.identifier);
+                if (identifier == null) try p.warnExpected(.identifier);
+                return p.addNode(.{
+                    .tag = .error_value,
+                    .main_token = main_token,
+                    .data = .{
+                        .lhs = period orelse 0,
+                        .rhs = identifier orelse 0,
+                    },
+                });
+            },
+        },
+        .l_paren => return p.addNode(.{
+            .tag = .grouped_expression,
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = try p.expectExpr(),
+                .rhs = try p.expectToken(.r_paren),
+            },
+        }),
+        else => return null_node,
+    }
+}
+
+fn expectPrimaryTypeExpr(p: *Parse) !Node.Index {
+    const node = try p.parsePrimaryTypeExpr();
+    if (node == 0) {
+        return p.fail(.expected_primary_type_expr);
+    }
+    return node;
+}
+
+/// ForPrefix <- KEYWORD_for LPAREN Expr RPAREN PtrIndexPayload
+///
+/// ForTypeExpr <- ForPrefix TypeExpr (KEYWORD_else TypeExpr)?
+fn parseForTypeExpr(p: *Parse) !Node.Index {
+    const for_token = p.eatToken(.keyword_for) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const array_expr = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    const found_payload = try p.parsePtrIndexPayload();
+    if (found_payload == 0) try p.warn(.expected_loop_payload);
+
+    const then_expr = try p.expectTypeExpr();
+    _ = p.eatToken(.keyword_else) orelse {
+        return p.addNode(.{
+            .tag = .for_simple,
+            .main_token = for_token,
+            .data = .{
+                .lhs = array_expr,
+                .rhs = then_expr,
+            },
+        });
+    };
+    const else_expr = try p.expectTypeExpr();
+    return p.addNode(.{
+        .tag = .@"for",
+        .main_token = for_token,
+        .data = .{
+            .lhs = array_expr,
+            .rhs = try p.addExtra(Node.If{
+                .then_expr = then_expr,
+                .else_expr = else_expr,
+            }),
+        },
+    });
+}
+
+/// WhilePrefix <- KEYWORD_while LPAREN Expr RPAREN PtrPayload? WhileContinueExpr?
+///
+/// WhileTypeExpr <- WhilePrefix TypeExpr (KEYWORD_else Payload? TypeExpr)?
+fn parseWhileTypeExpr(p: *Parse) !Node.Index {
+    const while_token = p.eatToken(.keyword_while) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const condition = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    _ = try p.parsePtrPayload();
+    const cont_expr = try p.parseWhileContinueExpr();
+
+    const then_expr = try p.expectTypeExpr();
+    _ = p.eatToken(.keyword_else) orelse {
+        if (cont_expr == 0) {
+            return p.addNode(.{
+                .tag = .while_simple,
+                .main_token = while_token,
+                .data = .{
+                    .lhs = condition,
+                    .rhs = then_expr,
+                },
+            });
+        } else {
+            return p.addNode(.{
+                .tag = .while_cont,
+                .main_token = while_token,
+                .data = .{
+                    .lhs = condition,
+                    .rhs = try p.addExtra(Node.WhileCont{
+                        .cont_expr = cont_expr,
+                        .then_expr = then_expr,
+                    }),
+                },
+            });
+        }
+    };
+    _ = try p.parsePayload();
+    const else_expr = try p.expectTypeExpr();
+    return p.addNode(.{
+        .tag = .@"while",
+        .main_token = while_token,
+        .data = .{
+            .lhs = condition,
+            .rhs = try p.addExtra(Node.While{
+                .cont_expr = cont_expr,
+                .then_expr = then_expr,
+                .else_expr = else_expr,
+            }),
+        },
+    });
+}
+
+/// SwitchExpr <- KEYWORD_switch LPAREN Expr RPAREN LBRACE SwitchProngList RBRACE
+fn expectSwitchExpr(p: *Parse) !Node.Index {
+    const switch_token = p.assertToken(.keyword_switch);
+    _ = try p.expectToken(.l_paren);
+    const expr_node = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    _ = try p.expectToken(.l_brace);
+    const cases = try p.parseSwitchProngList();
+    const trailing_comma = p.token_tags[p.tok_i - 1] == .comma;
+    _ = try p.expectToken(.r_brace);
+
+    return p.addNode(.{
+        .tag = if (trailing_comma) .switch_comma else .@"switch",
+        .main_token = switch_token,
+        .data = .{
+            .lhs = expr_node,
+            .rhs = try p.addExtra(Node.SubRange{
+                .start = cases.start,
+                .end = cases.end,
+            }),
+        },
+    });
+}
+
+/// AsmExpr <- KEYWORD_asm KEYWORD_volatile? LPAREN Expr AsmOutput? RPAREN
+///
+/// AsmOutput <- COLON AsmOutputList AsmInput?
+///
+/// AsmInput <- COLON AsmInputList AsmClobbers?
+///
+/// AsmClobbers <- COLON StringList
+///
+/// StringList <- (STRINGLITERAL COMMA)* STRINGLITERAL?
+///
+/// AsmOutputList <- (AsmOutputItem COMMA)* AsmOutputItem?
+///
+/// AsmInputList <- (AsmInputItem COMMA)* AsmInputItem?
+fn expectAsmExpr(p: *Parse) !Node.Index {
+    const asm_token = p.assertToken(.keyword_asm);
+    _ = p.eatToken(.keyword_volatile);
+    _ = try p.expectToken(.l_paren);
+    const template = try p.expectExpr();
+
+    if (p.eatToken(.r_paren)) |rparen| {
+        return p.addNode(.{
+            .tag = .asm_simple,
+            .main_token = asm_token,
+            .data = .{
+                .lhs = template,
+                .rhs = rparen,
+            },
+        });
+    }
+
+    _ = try p.expectToken(.colon);
+
+    const scratch_top = p.scratch.items.len;
+    defer p.scratch.shrinkRetainingCapacity(scratch_top);
+
+    while (true) {
+        const output_item = try p.parseAsmOutputItem();
+        if (output_item == 0) break;
+        try p.scratch.append(p.gpa, output_item);
+        switch (p.token_tags[p.tok_i]) {
+            .comma => p.tok_i += 1,
+            // All possible delimiters.
+            .colon, .r_paren, .r_brace, .r_bracket => break,
+            // Likely just a missing comma; give error but continue parsing.
+            else => try p.warnExpected(.comma),
+        }
+    }
+    if (p.eatToken(.colon)) |_| {
+        while (true) {
+            const input_item = try p.parseAsmInputItem();
+            if (input_item == 0) break;
+            try p.scratch.append(p.gpa, input_item);
+            switch (p.token_tags[p.tok_i]) {
+                .comma => p.tok_i += 1,
+                // All possible delimiters.
+                .colon, .r_paren, .r_brace, .r_bracket => break,
+                // Likely just a missing comma; give error but continue parsing.
+                else => try p.warnExpected(.comma),
+            }
+        }
+        if (p.eatToken(.colon)) |_| {
+            while (p.eatToken(.string_literal)) |_| {
+                switch (p.token_tags[p.tok_i]) {
+                    .comma => p.tok_i += 1,
+                    .colon, .r_paren, .r_brace, .r_bracket => break,
+                    // Likely just a missing comma; give error but continue parsing.
+                    else => try p.warnExpected(.comma),
+                }
+            }
+        }
+    }
+    const rparen = try p.expectToken(.r_paren);
+    const span = try p.listToSpan(p.scratch.items[scratch_top..]);
+    return p.addNode(.{
+        .tag = .@"asm",
+        .main_token = asm_token,
+        .data = .{
+            .lhs = template,
+            .rhs = try p.addExtra(Node.Asm{
+                .items_start = span.start,
+                .items_end = span.end,
+                .rparen = rparen,
+            }),
+        },
+    });
+}
+
+/// AsmOutputItem <- LBRACKET IDENTIFIER RBRACKET STRINGLITERAL LPAREN (MINUSRARROW TypeExpr / IDENTIFIER) RPAREN
+fn parseAsmOutputItem(p: *Parse) !Node.Index {
+    _ = p.eatToken(.l_bracket) orelse return null_node;
+    const identifier = try p.expectToken(.identifier);
+    _ = try p.expectToken(.r_bracket);
+    _ = try p.expectToken(.string_literal);
+    _ = try p.expectToken(.l_paren);
+    const type_expr: Node.Index = blk: {
+        if (p.eatToken(.arrow)) |_| {
+            break :blk try p.expectTypeExpr();
+        } else {
+            _ = try p.expectToken(.identifier);
+            break :blk null_node;
+        }
+    };
+    const rparen = try p.expectToken(.r_paren);
+    return p.addNode(.{
+        .tag = .asm_output,
+        .main_token = identifier,
+        .data = .{
+            .lhs = type_expr,
+            .rhs = rparen,
+        },
+    });
+}
+
+/// AsmInputItem <- LBRACKET IDENTIFIER RBRACKET STRINGLITERAL LPAREN Expr RPAREN
+fn parseAsmInputItem(p: *Parse) !Node.Index {
+    _ = p.eatToken(.l_bracket) orelse return null_node;
+    const identifier = try p.expectToken(.identifier);
+    _ = try p.expectToken(.r_bracket);
+    _ = try p.expectToken(.string_literal);
+    _ = try p.expectToken(.l_paren);
+    const expr = try p.expectExpr();
+    const rparen = try p.expectToken(.r_paren);
+    return p.addNode(.{
+        .tag = .asm_input,
+        .main_token = identifier,
+        .data = .{
+            .lhs = expr,
+            .rhs = rparen,
+        },
+    });
+}
+
+/// BreakLabel <- COLON IDENTIFIER
+fn parseBreakLabel(p: *Parse) !TokenIndex {
+    _ = p.eatToken(.colon) orelse return @as(TokenIndex, 0);
+    return p.expectToken(.identifier);
+}
+
+/// BlockLabel <- IDENTIFIER COLON
+fn parseBlockLabel(p: *Parse) TokenIndex {
+    if (p.token_tags[p.tok_i] == .identifier and
+        p.token_tags[p.tok_i + 1] == .colon)
+    {
+        const identifier = p.tok_i;
+        p.tok_i += 2;
+        return identifier;
+    }
+    return null_node;
+}
+
+/// FieldInit <- DOT IDENTIFIER EQUAL Expr
+fn parseFieldInit(p: *Parse) !Node.Index {
+    if (p.token_tags[p.tok_i + 0] == .period and
+        p.token_tags[p.tok_i + 1] == .identifier and
+        p.token_tags[p.tok_i + 2] == .equal)
+    {
+        p.tok_i += 3;
+        return p.expectExpr();
+    } else {
+        return null_node;
+    }
+}
+
+fn expectFieldInit(p: *Parse) !Node.Index {
+    if (p.token_tags[p.tok_i] != .period or
+        p.token_tags[p.tok_i + 1] != .identifier or
+        p.token_tags[p.tok_i + 2] != .equal)
+        return p.fail(.expected_initializer);
+
+    p.tok_i += 3;
+    return p.expectExpr();
+}
+
+/// WhileContinueExpr <- COLON LPAREN AssignExpr RPAREN
+fn parseWhileContinueExpr(p: *Parse) !Node.Index {
+    _ = p.eatToken(.colon) orelse {
+        if (p.token_tags[p.tok_i] == .l_paren and
+            p.tokensOnSameLine(p.tok_i - 1, p.tok_i))
+            return p.fail(.expected_continue_expr);
+        return null_node;
+    };
+    _ = try p.expectToken(.l_paren);
+    const node = try p.parseAssignExpr();
+    if (node == 0) return p.fail(.expected_expr_or_assignment);
+    _ = try p.expectToken(.r_paren);
+    return node;
+}
+
+/// LinkSection <- KEYWORD_linksection LPAREN Expr RPAREN
+fn parseLinkSection(p: *Parse) !Node.Index {
+    _ = p.eatToken(.keyword_linksection) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const expr_node = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    return expr_node;
+}
+
+/// CallConv <- KEYWORD_callconv LPAREN Expr RPAREN
+fn parseCallconv(p: *Parse) !Node.Index {
+    _ = p.eatToken(.keyword_callconv) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const expr_node = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    return expr_node;
+}
+
+/// AddrSpace <- KEYWORD_addrspace LPAREN Expr RPAREN
+fn parseAddrSpace(p: *Parse) !Node.Index {
+    _ = p.eatToken(.keyword_addrspace) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const expr_node = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    return expr_node;
+}
+
+/// This function can return null nodes and then still return nodes afterwards,
+/// such as in the case of anytype and `...`. Caller must look for rparen to find
+/// out when there are no more param decls left.
+///
+/// ParamDecl
+///     <- doc_comment? (KEYWORD_noalias / KEYWORD_comptime)? (IDENTIFIER COLON)? ParamType
+///      / DOT3
+///
+/// ParamType
+///     <- KEYWORD_anytype
+///      / TypeExpr
+fn expectParamDecl(p: *Parse) !Node.Index {
+    _ = try p.eatDocComments();
+    switch (p.token_tags[p.tok_i]) {
+        .keyword_noalias, .keyword_comptime => p.tok_i += 1,
+        .ellipsis3 => {
+            p.tok_i += 1;
+            return null_node;
+        },
+        else => {},
+    }
+    if (p.token_tags[p.tok_i] == .identifier and
+        p.token_tags[p.tok_i + 1] == .colon)
+    {
+        p.tok_i += 2;
+    }
+    switch (p.token_tags[p.tok_i]) {
+        .keyword_anytype => {
+            p.tok_i += 1;
+            return null_node;
+        },
+        else => return p.expectTypeExpr(),
+    }
+}
+
+/// Payload <- PIPE IDENTIFIER PIPE
+fn parsePayload(p: *Parse) !TokenIndex {
+    _ = p.eatToken(.pipe) orelse return @as(TokenIndex, 0);
+    const identifier = try p.expectToken(.identifier);
+    _ = try p.expectToken(.pipe);
+    return identifier;
+}
+
+/// PtrPayload <- PIPE ASTERISK? IDENTIFIER PIPE
+fn parsePtrPayload(p: *Parse) !TokenIndex {
+    _ = p.eatToken(.pipe) orelse return @as(TokenIndex, 0);
+    _ = p.eatToken(.asterisk);
+    const identifier = try p.expectToken(.identifier);
+    _ = try p.expectToken(.pipe);
+    return identifier;
+}
+
+/// Returns the first identifier token, if any.
+///
+/// PtrIndexPayload <- PIPE ASTERISK? IDENTIFIER (COMMA IDENTIFIER)? PIPE
+fn parsePtrIndexPayload(p: *Parse) !TokenIndex {
+    _ = p.eatToken(.pipe) orelse return @as(TokenIndex, 0);
+    _ = p.eatToken(.asterisk);
+    const identifier = try p.expectToken(.identifier);
+    if (p.eatToken(.comma) != null) {
+        _ = try p.expectToken(.identifier);
+    }
+    _ = try p.expectToken(.pipe);
+    return identifier;
+}
+
+/// SwitchProng <- KEYWORD_inline? SwitchCase EQUALRARROW PtrIndexPayload? AssignExpr
+///
+/// SwitchCase
+///     <- SwitchItem (COMMA SwitchItem)* COMMA?
+///      / KEYWORD_else
+fn parseSwitchProng(p: *Parse) !Node.Index {
+    const scratch_top = p.scratch.items.len;
+    defer p.scratch.shrinkRetainingCapacity(scratch_top);
+
+    const is_inline = p.eatToken(.keyword_inline) != null;
+
+    if (p.eatToken(.keyword_else) == null) {
+        while (true) {
+            const item = try p.parseSwitchItem();
+            if (item == 0) break;
+            try p.scratch.append(p.gpa, item);
+            if (p.eatToken(.comma) == null) break;
+        }
+        if (scratch_top == p.scratch.items.len) {
+            if (is_inline) p.tok_i -= 1;
+            return null_node;
+        }
+    }
+    const arrow_token = try p.expectToken(.equal_angle_bracket_right);
+    _ = try p.parsePtrIndexPayload();
+
+    const items = p.scratch.items[scratch_top..];
+    switch (items.len) {
+        0 => return p.addNode(.{
+            .tag = if (is_inline) .switch_case_inline_one else .switch_case_one,
+            .main_token = arrow_token,
+            .data = .{
+                .lhs = 0,
+                .rhs = try p.expectAssignExpr(),
+            },
+        }),
+        1 => return p.addNode(.{
+            .tag = if (is_inline) .switch_case_inline_one else .switch_case_one,
+            .main_token = arrow_token,
+            .data = .{
+                .lhs = items[0],
+                .rhs = try p.expectAssignExpr(),
+            },
+        }),
+        else => return p.addNode(.{
+            .tag = if (is_inline) .switch_case_inline else .switch_case,
+            .main_token = arrow_token,
+            .data = .{
+                .lhs = try p.addExtra(try p.listToSpan(items)),
+                .rhs = try p.expectAssignExpr(),
+            },
+        }),
+    }
+}
+
+/// SwitchItem <- Expr (DOT3 Expr)?
+fn parseSwitchItem(p: *Parse) !Node.Index {
+    const expr = try p.parseExpr();
+    if (expr == 0) return null_node;
+
+    if (p.eatToken(.ellipsis3)) |token| {
+        return p.addNode(.{
+            .tag = .switch_range,
+            .main_token = token,
+            .data = .{
+                .lhs = expr,
+                .rhs = try p.expectExpr(),
+            },
+        });
+    }
+    return expr;
+}
+
+const PtrModifiers = struct {
+    align_node: Node.Index,
+    addrspace_node: Node.Index,
+    bit_range_start: Node.Index,
+    bit_range_end: Node.Index,
+};
+
+fn parsePtrModifiers(p: *Parse) !PtrModifiers {
+    var result: PtrModifiers = .{
+        .align_node = 0,
+        .addrspace_node = 0,
+        .bit_range_start = 0,
+        .bit_range_end = 0,
+    };
+    var saw_const = false;
+    var saw_volatile = false;
+    var saw_allowzero = false;
+    var saw_addrspace = false;
+    while (true) {
+        switch (p.token_tags[p.tok_i]) {
+            .keyword_align => {
+                if (result.align_node != 0) {
+                    try p.warn(.extra_align_qualifier);
+                }
+                p.tok_i += 1;
+                _ = try p.expectToken(.l_paren);
+                result.align_node = try p.expectExpr();
+
+                if (p.eatToken(.colon)) |_| {
+                    result.bit_range_start = try p.expectExpr();
+                    _ = try p.expectToken(.colon);
+                    result.bit_range_end = try p.expectExpr();
+                }
+
+                _ = try p.expectToken(.r_paren);
+            },
+            .keyword_const => {
+                if (saw_const) {
+                    try p.warn(.extra_const_qualifier);
+                }
+                p.tok_i += 1;
+                saw_const = true;
+            },
+            .keyword_volatile => {
+                if (saw_volatile) {
+                    try p.warn(.extra_volatile_qualifier);
+                }
+                p.tok_i += 1;
+                saw_volatile = true;
+            },
+            .keyword_allowzero => {
+                if (saw_allowzero) {
+                    try p.warn(.extra_allowzero_qualifier);
+                }
+                p.tok_i += 1;
+                saw_allowzero = true;
+            },
+            .keyword_addrspace => {
+                if (saw_addrspace) {
+                    try p.warn(.extra_addrspace_qualifier);
+                }
+                result.addrspace_node = try p.parseAddrSpace();
+            },
+            else => return result,
+        }
+    }
+}
+
+/// SuffixOp
+///     <- LBRACKET Expr (DOT2 (Expr? (COLON Expr)?)?)? RBRACKET
+///      / DOT IDENTIFIER
+///      / DOTASTERISK
+///      / DOTQUESTIONMARK
+fn parseSuffixOp(p: *Parse, lhs: Node.Index) !Node.Index {
+    switch (p.token_tags[p.tok_i]) {
+        .l_bracket => {
+            const lbracket = p.nextToken();
+            const index_expr = try p.expectExpr();
+
+            if (p.eatToken(.ellipsis2)) |_| {
+                const end_expr = try p.parseExpr();
+                if (p.eatToken(.colon)) |_| {
+                    const sentinel = try p.expectExpr();
+                    _ = try p.expectToken(.r_bracket);
+                    return p.addNode(.{
+                        .tag = .slice_sentinel,
+                        .main_token = lbracket,
+                        .data = .{
+                            .lhs = lhs,
+                            .rhs = try p.addExtra(Node.SliceSentinel{
+                                .start = index_expr,
+                                .end = end_expr,
+                                .sentinel = sentinel,
+                            }),
+                        },
+                    });
+                }
+                _ = try p.expectToken(.r_bracket);
+                if (end_expr == 0) {
+                    return p.addNode(.{
+                        .tag = .slice_open,
+                        .main_token = lbracket,
+                        .data = .{
+                            .lhs = lhs,
+                            .rhs = index_expr,
+                        },
+                    });
+                }
+                return p.addNode(.{
+                    .tag = .slice,
+                    .main_token = lbracket,
+                    .data = .{
+                        .lhs = lhs,
+                        .rhs = try p.addExtra(Node.Slice{
+                            .start = index_expr,
+                            .end = end_expr,
+                        }),
+                    },
+                });
+            }
+            _ = try p.expectToken(.r_bracket);
+            return p.addNode(.{
+                .tag = .array_access,
+                .main_token = lbracket,
+                .data = .{
+                    .lhs = lhs,
+                    .rhs = index_expr,
+                },
+            });
+        },
+        .period_asterisk => return p.addNode(.{
+            .tag = .deref,
+            .main_token = p.nextToken(),
+            .data = .{
+                .lhs = lhs,
+                .rhs = undefined,
+            },
+        }),
+        .invalid_periodasterisks => {
+            try p.warn(.asterisk_after_ptr_deref);
+            return p.addNode(.{
+                .tag = .deref,
+                .main_token = p.nextToken(),
+                .data = .{
+                    .lhs = lhs,
+                    .rhs = undefined,
+                },
+            });
+        },
+        .period => switch (p.token_tags[p.tok_i + 1]) {
+            .identifier => return p.addNode(.{
+                .tag = .field_access,
+                .main_token = p.nextToken(),
+                .data = .{
+                    .lhs = lhs,
+                    .rhs = p.nextToken(),
+                },
+            }),
+            .question_mark => return p.addNode(.{
+                .tag = .unwrap_optional,
+                .main_token = p.nextToken(),
+                .data = .{
+                    .lhs = lhs,
+                    .rhs = p.nextToken(),
+                },
+            }),
+            .l_brace => {
+                // this a misplaced `.{`, handle the error somewhere else
+                return null_node;
+            },
+            else => {
+                p.tok_i += 1;
+                try p.warn(.expected_suffix_op);
+                return null_node;
+            },
+        },
+        else => return null_node,
+    }
+}
+
+/// Caller must have already verified the first token.
+///
+/// ContainerDeclAuto <- ContainerDeclType LBRACE container_doc_comment? ContainerMembers RBRACE
+///
+/// ContainerDeclType
+///     <- KEYWORD_struct (LPAREN Expr RPAREN)?
+///      / KEYWORD_opaque
+///      / KEYWORD_enum (LPAREN Expr RPAREN)?
+///      / KEYWORD_union (LPAREN (KEYWORD_enum (LPAREN Expr RPAREN)? / Expr) RPAREN)?
+fn parseContainerDeclAuto(p: *Parse) !Node.Index {
+    const main_token = p.nextToken();
+    const arg_expr = switch (p.token_tags[main_token]) {
+        .keyword_opaque => null_node,
+        .keyword_struct, .keyword_enum => blk: {
+            if (p.eatToken(.l_paren)) |_| {
+                const expr = try p.expectExpr();
+                _ = try p.expectToken(.r_paren);
+                break :blk expr;
+            } else {
+                break :blk null_node;
+            }
+        },
+        .keyword_union => blk: {
+            if (p.eatToken(.l_paren)) |_| {
+                if (p.eatToken(.keyword_enum)) |_| {
+                    if (p.eatToken(.l_paren)) |_| {
+                        const enum_tag_expr = try p.expectExpr();
+                        _ = try p.expectToken(.r_paren);
+                        _ = try p.expectToken(.r_paren);
+
+                        _ = try p.expectToken(.l_brace);
+                        const members = try p.parseContainerMembers();
+                        const members_span = try members.toSpan(p);
+                        _ = try p.expectToken(.r_brace);
+                        return p.addNode(.{
+                            .tag = switch (members.trailing) {
+                                true => .tagged_union_enum_tag_trailing,
+                                false => .tagged_union_enum_tag,
+                            },
+                            .main_token = main_token,
+                            .data = .{
+                                .lhs = enum_tag_expr,
+                                .rhs = try p.addExtra(members_span),
+                            },
+                        });
+                    } else {
+                        _ = try p.expectToken(.r_paren);
+
+                        _ = try p.expectToken(.l_brace);
+                        const members = try p.parseContainerMembers();
+                        _ = try p.expectToken(.r_brace);
+                        if (members.len <= 2) {
+                            return p.addNode(.{
+                                .tag = switch (members.trailing) {
+                                    true => .tagged_union_two_trailing,
+                                    false => .tagged_union_two,
+                                },
+                                .main_token = main_token,
+                                .data = .{
+                                    .lhs = members.lhs,
+                                    .rhs = members.rhs,
+                                },
+                            });
+                        } else {
+                            const span = try members.toSpan(p);
+                            return p.addNode(.{
+                                .tag = switch (members.trailing) {
+                                    true => .tagged_union_trailing,
+                                    false => .tagged_union,
+                                },
+                                .main_token = main_token,
+                                .data = .{
+                                    .lhs = span.start,
+                                    .rhs = span.end,
+                                },
+                            });
+                        }
+                    }
+                } else {
+                    const expr = try p.expectExpr();
+                    _ = try p.expectToken(.r_paren);
+                    break :blk expr;
+                }
+            } else {
+                break :blk null_node;
+            }
+        },
+        else => {
+            p.tok_i -= 1;
+            return p.fail(.expected_container);
+        },
+    };
+    _ = try p.expectToken(.l_brace);
+    const members = try p.parseContainerMembers();
+    _ = try p.expectToken(.r_brace);
+    if (arg_expr == 0) {
+        if (members.len <= 2) {
+            return p.addNode(.{
+                .tag = switch (members.trailing) {
+                    true => .container_decl_two_trailing,
+                    false => .container_decl_two,
+                },
+                .main_token = main_token,
+                .data = .{
+                    .lhs = members.lhs,
+                    .rhs = members.rhs,
+                },
+            });
+        } else {
+            const span = try members.toSpan(p);
+            return p.addNode(.{
+                .tag = switch (members.trailing) {
+                    true => .container_decl_trailing,
+                    false => .container_decl,
+                },
+                .main_token = main_token,
+                .data = .{
+                    .lhs = span.start,
+                    .rhs = span.end,
+                },
+            });
+        }
+    } else {
+        const span = try members.toSpan(p);
+        return p.addNode(.{
+            .tag = switch (members.trailing) {
+                true => .container_decl_arg_trailing,
+                false => .container_decl_arg,
+            },
+            .main_token = main_token,
+            .data = .{
+                .lhs = arg_expr,
+                .rhs = try p.addExtra(Node.SubRange{
+                    .start = span.start,
+                    .end = span.end,
+                }),
+            },
+        });
+    }
+}
+
+/// Give a helpful error message for those transitioning from
+/// C's 'struct Foo {};' to Zig's 'const Foo = struct {};'.
+fn parseCStyleContainer(p: *Parse) Error!bool {
+    const main_token = p.tok_i;
+    switch (p.token_tags[p.tok_i]) {
+        .keyword_enum, .keyword_union, .keyword_struct => {},
+        else => return false,
+    }
+    const identifier = p.tok_i + 1;
+    if (p.token_tags[identifier] != .identifier) return false;
+    p.tok_i += 2;
+
+    try p.warnMsg(.{
+        .tag = .c_style_container,
+        .token = identifier,
+        .extra = .{ .expected_tag = p.token_tags[main_token] },
+    });
+    try p.warnMsg(.{
+        .tag = .zig_style_container,
+        .is_note = true,
+        .token = identifier,
+        .extra = .{ .expected_tag = p.token_tags[main_token] },
+    });
+
+    _ = try p.expectToken(.l_brace);
+    _ = try p.parseContainerMembers();
+    _ = try p.expectToken(.r_brace);
+    try p.expectSemicolon(.expected_semi_after_decl, true);
+    return true;
+}
+
+/// Holds temporary data until we are ready to construct the full ContainerDecl AST node.
+///
+/// ByteAlign <- KEYWORD_align LPAREN Expr RPAREN
+fn parseByteAlign(p: *Parse) !Node.Index {
+    _ = p.eatToken(.keyword_align) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const expr = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    return expr;
+}
+
+/// SwitchProngList <- (SwitchProng COMMA)* SwitchProng?
+fn parseSwitchProngList(p: *Parse) !Node.SubRange {
+    const scratch_top = p.scratch.items.len;
+    defer p.scratch.shrinkRetainingCapacity(scratch_top);
+
+    while (true) {
+        const item = try parseSwitchProng(p);
+        if (item == 0) break;
+
+        try p.scratch.append(p.gpa, item);
+
+        switch (p.token_tags[p.tok_i]) {
+            .comma => p.tok_i += 1,
+            // All possible delimiters.
+            .colon, .r_paren, .r_brace, .r_bracket => break,
+            // Likely just a missing comma; give error but continue parsing.
+            else => try p.warn(.expected_comma_after_switch_prong),
+        }
+    }
+    return p.listToSpan(p.scratch.items[scratch_top..]);
+}
+
+/// ParamDeclList <- (ParamDecl COMMA)* ParamDecl?
+fn parseParamDeclList(p: *Parse) !SmallSpan {
+    _ = try p.expectToken(.l_paren);
+    const scratch_top = p.scratch.items.len;
+    defer p.scratch.shrinkRetainingCapacity(scratch_top);
+    var varargs: union(enum) { none, seen, nonfinal: TokenIndex } = .none;
+    while (true) {
+        if (p.eatToken(.r_paren)) |_| break;
+        if (varargs == .seen) varargs = .{ .nonfinal = p.tok_i };
+        const param = try p.expectParamDecl();
+        if (param != 0) {
+            try p.scratch.append(p.gpa, param);
+        } else if (p.token_tags[p.tok_i - 1] == .ellipsis3) {
+            if (varargs == .none) varargs = .seen;
+        }
+        switch (p.token_tags[p.tok_i]) {
+            .comma => p.tok_i += 1,
+            .r_paren => {
+                p.tok_i += 1;
+                break;
+            },
+            .colon, .r_brace, .r_bracket => return p.failExpected(.r_paren),
+            // Likely just a missing comma; give error but continue parsing.
+            else => try p.warn(.expected_comma_after_param),
+        }
+    }
+    if (varargs == .nonfinal) {
+        try p.warnMsg(.{ .tag = .varargs_nonfinal, .token = varargs.nonfinal });
+    }
+    const params = p.scratch.items[scratch_top..];
+    return switch (params.len) {
+        0 => SmallSpan{ .zero_or_one = 0 },
+        1 => SmallSpan{ .zero_or_one = params[0] },
+        else => SmallSpan{ .multi = try p.listToSpan(params) },
+    };
+}
+
+/// FnCallArguments <- LPAREN ExprList RPAREN
+///
+/// ExprList <- (Expr COMMA)* Expr?
+fn parseBuiltinCall(p: *Parse) !Node.Index {
+    const builtin_token = p.assertToken(.builtin);
+    if (p.token_tags[p.nextToken()] != .l_paren) {
+        p.tok_i -= 1;
+        try p.warn(.expected_param_list);
+        // Pretend this was an identifier so we can continue parsing.
+        return p.addNode(.{
+            .tag = .identifier,
+            .main_token = builtin_token,
+            .data = .{
+                .lhs = undefined,
+                .rhs = undefined,
+            },
+        });
+    }
+    const scratch_top = p.scratch.items.len;
+    defer p.scratch.shrinkRetainingCapacity(scratch_top);
+    while (true) {
+        if (p.eatToken(.r_paren)) |_| break;
+        const param = try p.expectExpr();
+        try p.scratch.append(p.gpa, param);
+        switch (p.token_tags[p.tok_i]) {
+            .comma => p.tok_i += 1,
+            .r_paren => {
+                p.tok_i += 1;
+                break;
+            },
+            // Likely just a missing comma; give error but continue parsing.
+            else => try p.warn(.expected_comma_after_arg),
+        }
+    }
+    const comma = (p.token_tags[p.tok_i - 2] == .comma);
+    const params = p.scratch.items[scratch_top..];
+    switch (params.len) {
+        0 => return p.addNode(.{
+            .tag = .builtin_call_two,
+            .main_token = builtin_token,
+            .data = .{
+                .lhs = 0,
+                .rhs = 0,
+            },
+        }),
+        1 => return p.addNode(.{
+            .tag = if (comma) .builtin_call_two_comma else .builtin_call_two,
+            .main_token = builtin_token,
+            .data = .{
+                .lhs = params[0],
+                .rhs = 0,
+            },
+        }),
+        2 => return p.addNode(.{
+            .tag = if (comma) .builtin_call_two_comma else .builtin_call_two,
+            .main_token = builtin_token,
+            .data = .{
+                .lhs = params[0],
+                .rhs = params[1],
+            },
+        }),
+        else => {
+            const span = try p.listToSpan(params);
+            return p.addNode(.{
+                .tag = if (comma) .builtin_call_comma else .builtin_call,
+                .main_token = builtin_token,
+                .data = .{
+                    .lhs = span.start,
+                    .rhs = span.end,
+                },
+            });
+        },
+    }
+}
+
+/// IfPrefix <- KEYWORD_if LPAREN Expr RPAREN PtrPayload?
+fn parseIf(p: *Parse, comptime bodyParseFn: fn (p: *Parse) Error!Node.Index) !Node.Index {
+    const if_token = p.eatToken(.keyword_if) orelse return null_node;
+    _ = try p.expectToken(.l_paren);
+    const condition = try p.expectExpr();
+    _ = try p.expectToken(.r_paren);
+    _ = try p.parsePtrPayload();
+
+    const then_expr = try bodyParseFn(p);
+    assert(then_expr != 0);
+
+    _ = p.eatToken(.keyword_else) orelse return p.addNode(.{
+        .tag = .if_simple,
+        .main_token = if_token,
+        .data = .{
+            .lhs = condition,
+            .rhs = then_expr,
+        },
+    });
+    _ = try p.parsePayload();
+    const else_expr = try bodyParseFn(p);
+    assert(then_expr != 0);
+
+    return p.addNode(.{
+        .tag = .@"if",
+        .main_token = if_token,
+        .data = .{
+            .lhs = condition,
+            .rhs = try p.addExtra(Node.If{
+                .then_expr = then_expr,
+                .else_expr = else_expr,
+            }),
+        },
+    });
+}
+
+/// Skips over doc comment tokens. Returns the first one, if any.
+fn eatDocComments(p: *Parse) !?TokenIndex {
+    if (p.eatToken(.doc_comment)) |tok| {
+        var first_line = tok;
+        if (tok > 0 and tokensOnSameLine(p, tok - 1, tok)) {
+            try p.warnMsg(.{
+                .tag = .same_line_doc_comment,
+                .token = tok,
+            });
+            first_line = p.eatToken(.doc_comment) orelse return null;
+        }
+        while (p.eatToken(.doc_comment)) |_| {}
+        return first_line;
+    }
+    return null;
+}
+
+fn tokensOnSameLine(p: *Parse, token1: TokenIndex, token2: TokenIndex) bool {
+    return std.mem.indexOfScalar(u8, p.source[p.token_starts[token1]..p.token_starts[token2]], '\n') == null;
+}
+
+fn eatToken(p: *Parse, tag: Token.Tag) ?TokenIndex {
+    return if (p.token_tags[p.tok_i] == tag) p.nextToken() else null;
+}
+
+fn assertToken(p: *Parse, tag: Token.Tag) TokenIndex {
+    const token = p.nextToken();
+    assert(p.token_tags[token] == tag);
+    return token;
+}
+
+fn expectToken(p: *Parse, tag: Token.Tag) Error!TokenIndex {
+    if (p.token_tags[p.tok_i] != tag) {
+        return p.failMsg(.{
+            .tag = .expected_token,
+            .token = p.tok_i,
+            .extra = .{ .expected_tag = tag },
+        });
+    }
+    return p.nextToken();
+}
+
+fn expectSemicolon(p: *Parse, error_tag: AstError.Tag, recoverable: bool) Error!void {
+    if (p.token_tags[p.tok_i] == .semicolon) {
+        _ = p.nextToken();
+        return;
+    }
+    try p.warn(error_tag);
+    if (!recoverable) return error.ParseError;
+}
+
+fn nextToken(p: *Parse) TokenIndex {
+    const result = p.tok_i;
+    p.tok_i += 1;
+    return result;
+}
+
+const null_node: Node.Index = 0;
+
+const Parse = @This();
+const std = @import("../std.zig");
+const assert = std.debug.assert;
+const Allocator = std.mem.Allocator;
+const Ast = std.zig.Ast;
+const Node = Ast.Node;
+const AstError = Ast.Error;
+const TokenIndex = Ast.TokenIndex;
+const Token = std.zig.Token;
+
+test {
+    _ = @import("parser_test.zig");
+}

lib/std/zig/parse.zig

@@ -1,3852 +0,0 @@
-const std = @import("../std.zig");
-const assert = std.debug.assert;
-const Allocator = std.mem.Allocator;
-const Ast = std.zig.Ast;
-const Node = Ast.Node;
-const AstError = Ast.Error;
-const TokenIndex = Ast.TokenIndex;
-const Token = std.zig.Token;
-
-pub const Error = error{ParseError} || Allocator.Error;
-
-/// Result should be freed with tree.deinit() when there are
-/// no more references to any of the tokens or nodes.
-pub fn parse(gpa: Allocator, source: [:0]const u8) Allocator.Error!Ast {
-    var tokens = Ast.TokenList{};
-    defer tokens.deinit(gpa);
-
-    // Empirically, the zig std lib has an 8:1 ratio of source bytes to token count.
-    const estimated_token_count = source.len / 8;
-    try tokens.ensureTotalCapacity(gpa, estimated_token_count);
-
-    var tokenizer = std.zig.Tokenizer.init(source);
-    while (true) {
-        const token = tokenizer.next();
-        try tokens.append(gpa, .{
-            .tag = token.tag,
-            .start = @intCast(u32, token.loc.start),
-        });
-        if (token.tag == .eof) break;
-    }
-
-    var parser: Parser = .{
-        .source = source,
-        .gpa = gpa,
-        .token_tags = tokens.items(.tag),
-        .token_starts = tokens.items(.start),
-        .errors = .{},
-        .nodes = .{},
-        .extra_data = .{},
-        .scratch = .{},
-        .tok_i = 0,
-    };
-    defer parser.errors.deinit(gpa);
-    defer parser.nodes.deinit(gpa);
-    defer parser.extra_data.deinit(gpa);
-    defer parser.scratch.deinit(gpa);
-
-    // Empirically, Zig source code has a 2:1 ratio of tokens to AST nodes.
-    // Make sure at least 1 so we can use appendAssumeCapacity on the root node below.
-    const estimated_node_count = (tokens.len + 2) / 2;
-    try parser.nodes.ensureTotalCapacity(gpa, estimated_node_count);
-
-    try parser.parseRoot();
-
-    // TODO experiment with compacting the MultiArrayList slices here
-    return Ast{
-        .source = source,
-        .tokens = tokens.toOwnedSlice(),
-        .nodes = parser.nodes.toOwnedSlice(),
-        .extra_data = try parser.extra_data.toOwnedSlice(gpa),
-        .errors = try parser.errors.toOwnedSlice(gpa),
-    };
-}
-
-const null_node: Node.Index = 0;
-
-/// Represents in-progress parsing, will be converted to an Ast after completion.
-const Parser = struct {
-    gpa: Allocator,
-    source: []const u8,
-    token_tags: []const Token.Tag,
-    token_starts: []const Ast.ByteOffset,
-    tok_i: TokenIndex,
-    errors: std.ArrayListUnmanaged(AstError),
-    nodes: Ast.NodeList,
-    extra_data: std.ArrayListUnmanaged(Node.Index),
-    scratch: std.ArrayListUnmanaged(Node.Index),
-
-    const SmallSpan = union(enum) {
-        zero_or_one: Node.Index,
-        multi: Node.SubRange,
-    };
-
-    const Members = struct {
-        len: usize,
-        lhs: Node.Index,
-        rhs: Node.Index,
-        trailing: bool,
-
-        fn toSpan(self: Members, p: *Parser) !Node.SubRange {
-            if (self.len <= 2) {
-                const nodes = [2]Node.Index{ self.lhs, self.rhs };
-                return p.listToSpan(nodes[0..self.len]);
-            } else {
-                return Node.SubRange{ .start = self.lhs, .end = self.rhs };
-            }
-        }
-    };
-
-    fn listToSpan(p: *Parser, list: []const Node.Index) !Node.SubRange {
-        try p.extra_data.appendSlice(p.gpa, list);
-        return Node.SubRange{
-            .start = @intCast(Node.Index, p.extra_data.items.len - list.len),
-            .end = @intCast(Node.Index, p.extra_data.items.len),
-        };
-    }
-
-    fn addNode(p: *Parser, elem: Ast.NodeList.Elem) Allocator.Error!Node.Index {
-        const result = @intCast(Node.Index, p.nodes.len);
-        try p.nodes.append(p.gpa, elem);
-        return result;
-    }
-
-    fn setNode(p: *Parser, i: usize, elem: Ast.NodeList.Elem) Node.Index {
-        p.nodes.set(i, elem);
-        return @intCast(Node.Index, i);
-    }
-
-    fn reserveNode(p: *Parser, tag: Ast.Node.Tag) !usize {
-        try p.nodes.resize(p.gpa, p.nodes.len + 1);
-        p.nodes.items(.tag)[p.nodes.len - 1] = tag;
-        return p.nodes.len - 1;
-    }
-
-    fn unreserveNode(p: *Parser, node_index: usize) void {
-        if (p.nodes.len == node_index) {
-            p.nodes.resize(p.gpa, p.nodes.len - 1) catch unreachable;
-        } else {
-            // There is zombie node left in the tree, let's make it as inoffensive as possible
-            // (sadly there's no no-op node)
-            p.nodes.items(.tag)[node_index] = .unreachable_literal;
-            p.nodes.items(.main_token)[node_index] = p.tok_i;
-        }
-    }
-
-    fn addExtra(p: *Parser, extra: anytype) Allocator.Error!Node.Index {
-        const fields = std.meta.fields(@TypeOf(extra));
-        try p.extra_data.ensureUnusedCapacity(p.gpa, fields.len);
-        const result = @intCast(u32, p.extra_data.items.len);
-        inline for (fields) |field| {
-            comptime assert(field.type == Node.Index);
-            p.extra_data.appendAssumeCapacity(@field(extra, field.name));
-        }
-        return result;
-    }
-
-    fn warnExpected(p: *Parser, expected_token: Token.Tag) error{OutOfMemory}!void {
-        @setCold(true);
-        try p.warnMsg(.{
-            .tag = .expected_token,
-            .token = p.tok_i,
-            .extra = .{ .expected_tag = expected_token },
-        });
-    }
-
-    fn warn(p: *Parser, error_tag: AstError.Tag) error{OutOfMemory}!void {
-        @setCold(true);
-        try p.warnMsg(.{ .tag = error_tag, .token = p.tok_i });
-    }
-
-    fn warnMsg(p: *Parser, msg: Ast.Error) error{OutOfMemory}!void {
-        @setCold(true);
-        switch (msg.tag) {
-            .expected_semi_after_decl,
-            .expected_semi_after_stmt,
-            .expected_comma_after_field,
-            .expected_comma_after_arg,
-            .expected_comma_after_param,
-            .expected_comma_after_initializer,
-            .expected_comma_after_switch_prong,
-            .expected_semi_or_else,
-            .expected_semi_or_lbrace,
-            .expected_token,
-            .expected_block,
-            .expected_block_or_assignment,
-            .expected_block_or_expr,
-            .expected_block_or_field,
-            .expected_expr,
-            .expected_expr_or_assignment,
-            .expected_fn,
-            .expected_inlinable,
-            .expected_labelable,
-            .expected_param_list,
-            .expected_prefix_expr,
-            .expected_primary_type_expr,
-            .expected_pub_item,
-            .expected_return_type,
-            .expected_suffix_op,
-            .expected_type_expr,
-            .expected_var_decl,
-            .expected_var_decl_or_fn,
-            .expected_loop_payload,
-            .expected_container,
-            => if (msg.token != 0 and !p.tokensOnSameLine(msg.token - 1, msg.token)) {
-                var copy = msg;
-                copy.token_is_prev = true;
-                copy.token -= 1;
-                return p.errors.append(p.gpa, copy);
-            },
-            else => {},
-        }
-        try p.errors.append(p.gpa, msg);
-    }
-
-    fn fail(p: *Parser, tag: Ast.Error.Tag) error{ ParseError, OutOfMemory } {
-        @setCold(true);
-        return p.failMsg(.{ .tag = tag, .token = p.tok_i });
-    }
-
-    fn failExpected(p: *Parser, expected_token: Token.Tag) error{ ParseError, OutOfMemory } {
-        @setCold(true);
-        return p.failMsg(.{
-            .tag = .expected_token,
-            .token = p.tok_i,
-            .extra = .{ .expected_tag = expected_token },
-        });
-    }
-
-    fn failMsg(p: *Parser, msg: Ast.Error) error{ ParseError, OutOfMemory } {
-        @setCold(true);
-        try p.warnMsg(msg);
-        return error.ParseError;
-    }
-
-    /// Root <- skip container_doc_comment? ContainerMembers eof
-    fn parseRoot(p: *Parser) !void {
-        // Root node must be index 0.
-        p.nodes.appendAssumeCapacity(.{
-            .tag = .root,
-            .main_token = 0,
-            .data = undefined,
-        });
-        const root_members = try p.parseContainerMembers();
-        const root_decls = try root_members.toSpan(p);
-        if (p.token_tags[p.tok_i] != .eof) {
-            try p.warnExpected(.eof);
-        }
-        p.nodes.items(.data)[0] = .{
-            .lhs = root_decls.start,
-            .rhs = root_decls.end,
-        };
-    }
-
-    /// ContainerMembers <- ContainerDeclarations (ContainerField COMMA)* (ContainerField / ContainerDeclarations)
-    ///
-    /// ContainerDeclarations
-    ///     <- TestDecl ContainerDeclarations
-    ///      / ComptimeDecl ContainerDeclarations
-    ///      / doc_comment? KEYWORD_pub? Decl ContainerDeclarations
-    ///      /
-    ///
-    /// ComptimeDecl <- KEYWORD_comptime Block
-    fn parseContainerMembers(p: *Parser) !Members {
-        const scratch_top = p.scratch.items.len;
-        defer p.scratch.shrinkRetainingCapacity(scratch_top);
-
-        var field_state: union(enum) {
-            /// No fields have been seen.
-            none,
-            /// Currently parsing fields.
-            seen,
-            /// Saw fields and then a declaration after them.
-            /// Payload is first token of previous declaration.
-            end: Node.Index,
-            /// There was a declaration between fields, don't report more errors.
-            err,
-        } = .none;
-
-        var last_field: TokenIndex = undefined;
-
-        // Skip container doc comments.
-        while (p.eatToken(.container_doc_comment)) |_| {}
-
-        var trailing = false;
-        while (true) {
-            const doc_comment = try p.eatDocComments();
-
-            switch (p.token_tags[p.tok_i]) {
-                .keyword_test => {
-                    if (doc_comment) |some| {
-                        try p.warnMsg(.{ .tag = .test_doc_comment, .token = some });
-                    }
-                    const test_decl_node = try p.expectTestDeclRecoverable();
-                    if (test_decl_node != 0) {
-                        if (field_state == .seen) {
-                            field_state = .{ .end = test_decl_node };
-                        }
-                        try p.scratch.append(p.gpa, test_decl_node);
-                    }
-                    trailing = false;
-                },
-                .keyword_comptime => switch (p.token_tags[p.tok_i + 1]) {
-                    .l_brace => {
-                        if (doc_comment) |some| {
-                            try p.warnMsg(.{ .tag = .comptime_doc_comment, .token = some });
-                        }
-                        const comptime_token = p.nextToken();
-                        const block = p.parseBlock() catch |err| switch (err) {
-                            error.OutOfMemory => return error.OutOfMemory,
-                            error.ParseError => blk: {
-                                p.findNextContainerMember();
-                                break :blk null_node;
-                            },
-                        };
-                        if (block != 0) {
-                            const comptime_node = try p.addNode(.{
-                                .tag = .@"comptime",
-                                .main_token = comptime_token,
-                                .data = .{
-                                    .lhs = block,
-                                    .rhs = undefined,
-                                },
-                            });
-                            if (field_state == .seen) {
-                                field_state = .{ .end = comptime_node };
-                            }
-                            try p.scratch.append(p.gpa, comptime_node);
-                        }
-                        trailing = false;
-                    },
-                    else => {
-                        const identifier = p.tok_i;
-                        defer last_field = identifier;
-                        const container_field = p.expectContainerField() catch |err| switch (err) {
-                            error.OutOfMemory => return error.OutOfMemory,
-                            error.ParseError => {
-                                p.findNextContainerMember();
-                                continue;
-                            },
-                        };
-                        switch (field_state) {
-                            .none => field_state = .seen,
-                            .err, .seen => {},
-                            .end => |node| {
-                                try p.warnMsg(.{
-                                    .tag = .decl_between_fields,
-                                    .token = p.nodes.items(.main_token)[node],
-                                });
-                                try p.warnMsg(.{
-                                    .tag = .previous_field,
-                                    .is_note = true,
-                                    .token = last_field,
-                                });
-                                try p.warnMsg(.{
-                                    .tag = .next_field,
-                                    .is_note = true,
-                                    .token = identifier,
-                                });
-                                // Continue parsing; error will be reported later.
-                                field_state = .err;
-                            },
-                        }
-                        try p.scratch.append(p.gpa, container_field);
-                        switch (p.token_tags[p.tok_i]) {
-                            .comma => {
-                                p.tok_i += 1;
-                                trailing = true;
-                                continue;
-                            },
-                            .r_brace, .eof => {
-                                trailing = false;
-                                break;
-                            },
-                            else => {},
-                        }
-                        // There is not allowed to be a decl after a field with no comma.
-                        // Report error but recover parser.
-                        try p.warn(.expected_comma_after_field);
-                        p.findNextContainerMember();
-                    },
-                },
-                .keyword_pub => {
-                    p.tok_i += 1;
-                    const top_level_decl = try p.expectTopLevelDeclRecoverable();
-                    if (top_level_decl != 0) {
-                        if (field_state == .seen) {
-                            field_state = .{ .end = top_level_decl };
-                        }
-                        try p.scratch.append(p.gpa, top_level_decl);
-                    }
-                    trailing = p.token_tags[p.tok_i - 1] == .semicolon;
-                },
-                .keyword_usingnamespace => {
-                    const node = try p.expectUsingNamespaceRecoverable();
-                    if (node != 0) {
-                        if (field_state == .seen) {
-                            field_state = .{ .end = node };
-                        }
-                        try p.scratch.append(p.gpa, node);
-                    }
-                    trailing = p.token_tags[p.tok_i - 1] == .semicolon;
-                },
-                .keyword_const,
-                .keyword_var,
-                .keyword_threadlocal,
-                .keyword_export,
-                .keyword_extern,
-                .keyword_inline,
-                .keyword_noinline,
-                .keyword_fn,
-                => {
-                    const top_level_decl = try p.expectTopLevelDeclRecoverable();
-                    if (top_level_decl != 0) {
-                        if (field_state == .seen) {
-                            field_state = .{ .end = top_level_decl };
-                        }
-                        try p.scratch.append(p.gpa, top_level_decl);
-                    }
-                    trailing = p.token_tags[p.tok_i - 1] == .semicolon;
-                },
-                .eof, .r_brace => {
-                    if (doc_comment) |tok| {
-                        try p.warnMsg(.{
-                            .tag = .unattached_doc_comment,
-                            .token = tok,
-                        });
-                    }
-                    break;
-                },
-                else => {
-                    const c_container = p.parseCStyleContainer() catch |err| switch (err) {
-                        error.OutOfMemory => return error.OutOfMemory,
-                        error.ParseError => false,
-                    };
-                    if (c_container) continue;
-
-                    const identifier = p.tok_i;
-                    defer last_field = identifier;
-                    const container_field = p.expectContainerField() catch |err| switch (err) {
-                        error.OutOfMemory => return error.OutOfMemory,
-                        error.ParseError => {
-                            p.findNextContainerMember();
-                            continue;
-                        },
-                    };
-                    switch (field_state) {
-                        .none => field_state = .seen,
-                        .err, .seen => {},
-                        .end => |node| {
-                            try p.warnMsg(.{
-                                .tag = .decl_between_fields,
-                                .token = p.nodes.items(.main_token)[node],
-                            });
-                            try p.warnMsg(.{
-                                .tag = .previous_field,
-                                .is_note = true,
-                                .token = last_field,
-                            });
-                            try p.warnMsg(.{
-                                .tag = .next_field,
-                                .is_note = true,
-                                .token = identifier,
-                            });
-                            // Continue parsing; error will be reported later.
-                            field_state = .err;
-                        },
-                    }
-                    try p.scratch.append(p.gpa, container_field);
-                    switch (p.token_tags[p.tok_i]) {
-                        .comma => {
-                            p.tok_i += 1;
-                            trailing = true;
-                            continue;
-                        },
-                        .r_brace, .eof => {
-                            trailing = false;
-                            break;
-                        },
-                        else => {},
-                    }
-                    // There is not allowed to be a decl after a field with no comma.
-                    // Report error but recover parser.
-                    try p.warn(.expected_comma_after_field);
-                    if (p.token_tags[p.tok_i] == .semicolon and p.token_tags[identifier] == .identifier) {
-                        try p.warnMsg(.{
-                            .tag = .var_const_decl,
-                            .is_note = true,
-                            .token = identifier,
-                        });
-                    }
-                    p.findNextContainerMember();
-                    continue;
-                },
-            }
-        }
-
-        const items = p.scratch.items[scratch_top..];
-        switch (items.len) {
-            0 => return Members{
-                .len = 0,
-                .lhs = 0,
-                .rhs = 0,
-                .trailing = trailing,
-            },
-            1 => return Members{
-                .len = 1,
-                .lhs = items[0],
-                .rhs = 0,
-                .trailing = trailing,
-            },
-            2 => return Members{
-                .len = 2,
-                .lhs = items[0],
-                .rhs = items[1],
-                .trailing = trailing,
-            },
-            else => {
-                const span = try p.listToSpan(items);
-                return Members{
-                    .len = items.len,
-                    .lhs = span.start,
-                    .rhs = span.end,
-                    .trailing = trailing,
-                };
-            },
-        }
-    }
-
-    /// Attempts to find next container member by searching for certain tokens
-    fn findNextContainerMember(p: *Parser) void {
-        var level: u32 = 0;
-        while (true) {
-            const tok = p.nextToken();
-            switch (p.token_tags[tok]) {
-                // Any of these can start a new top level declaration.
-                .keyword_test,
-                .keyword_comptime,
-                .keyword_pub,
-                .keyword_export,
-                .keyword_extern,
-                .keyword_inline,
-                .keyword_noinline,
-                .keyword_usingnamespace,
-                .keyword_threadlocal,
-                .keyword_const,
-                .keyword_var,
-                .keyword_fn,
-                => {
-                    if (level == 0) {
-                        p.tok_i -= 1;
-                        return;
-                    }
-                },
-                .identifier => {
-                    if (p.token_tags[tok + 1] == .comma and level == 0) {
-                        p.tok_i -= 1;
-                        return;
-                    }
-                },
-                .comma, .semicolon => {
-                    // this decl was likely meant to end here
-                    if (level == 0) {
-                        return;
-                    }
-                },
-                .l_paren, .l_bracket, .l_brace => level += 1,
-                .r_paren, .r_bracket => {
-                    if (level != 0) level -= 1;
-                },
-                .r_brace => {
-                    if (level == 0) {
-                        // end of container, exit
-                        p.tok_i -= 1;
-                        return;
-                    }
-                    level -= 1;
-                },
-                .eof => {
-                    p.tok_i -= 1;
-                    return;
-                },
-                else => {},
-            }
-        }
-    }
-
-    /// Attempts to find the next statement by searching for a semicolon
-    fn findNextStmt(p: *Parser) void {
-        var level: u32 = 0;
-        while (true) {
-            const tok = p.nextToken();
-            switch (p.token_tags[tok]) {
-                .l_brace => level += 1,
-                .r_brace => {
-                    if (level == 0) {
-                        p.tok_i -= 1;
-                        return;
-                    }
-                    level -= 1;
-                },
-                .semicolon => {
-                    if (level == 0) {
-                        return;
-                    }
-                },
-                .eof => {
-                    p.tok_i -= 1;
-                    return;
-                },
-                else => {},
-            }
-        }
-    }
-
-    /// TestDecl <- KEYWORD_test (STRINGLITERALSINGLE / IDENTIFIER)? Block
-    fn expectTestDecl(p: *Parser) !Node.Index {
-        const test_token = p.assertToken(.keyword_test);
-        const name_token = switch (p.token_tags[p.nextToken()]) {
-            .string_literal, .identifier => p.tok_i - 1,
-            else => blk: {
-                p.tok_i -= 1;
-                break :blk null;
-            },
-        };
-        const block_node = try p.parseBlock();
-        if (block_node == 0) return p.fail(.expected_block);
-        return p.addNode(.{
-            .tag = .test_decl,
-            .main_token = test_token,
-            .data = .{
-                .lhs = name_token orelse 0,
-                .rhs = block_node,
-            },
-        });
-    }
-
-    fn expectTestDeclRecoverable(p: *Parser) error{OutOfMemory}!Node.Index {
-        return p.expectTestDecl() catch |err| switch (err) {
-            error.OutOfMemory => return error.OutOfMemory,
-            error.ParseError => {
-                p.findNextContainerMember();
-                return null_node;
-            },
-        };
-    }
-
-    /// Decl
-    ///     <- (KEYWORD_export / KEYWORD_extern STRINGLITERALSINGLE? / (KEYWORD_inline / KEYWORD_noinline))? FnProto (SEMICOLON / Block)
-    ///      / (KEYWORD_export / KEYWORD_extern STRINGLITERALSINGLE?)? KEYWORD_threadlocal? VarDecl
-    ///      / KEYWORD_usingnamespace Expr SEMICOLON
-    fn expectTopLevelDecl(p: *Parser) !Node.Index {
-        const extern_export_inline_token = p.nextToken();
-        var is_extern: bool = false;
-        var expect_fn: bool = false;
-        var expect_var_or_fn: bool = false;
-        switch (p.token_tags[extern_export_inline_token]) {
-            .keyword_extern => {
-                _ = p.eatToken(.string_literal);
-                is_extern = true;
-                expect_var_or_fn = true;
-            },
-            .keyword_export => expect_var_or_fn = true,
-            .keyword_inline, .keyword_noinline => expect_fn = true,
-            else => p.tok_i -= 1,
-        }
-        const fn_proto = try p.parseFnProto();
-        if (fn_proto != 0) {
-            switch (p.token_tags[p.tok_i]) {
-                .semicolon => {
-                    p.tok_i += 1;
-                    return fn_proto;
-                },
-                .l_brace => {
-                    if (is_extern) {
-                        try p.warnMsg(.{ .tag = .extern_fn_body, .token = extern_export_inline_token });
-                        return null_node;
-                    }
-                    const fn_decl_index = try p.reserveNode(.fn_decl);
-                    errdefer p.unreserveNode(fn_decl_index);
-
-                    const body_block = try p.parseBlock();
-                    assert(body_block != 0);
-                    return p.setNode(fn_decl_index, .{
-                        .tag = .fn_decl,
-                        .main_token = p.nodes.items(.main_token)[fn_proto],
-                        .data = .{
-                            .lhs = fn_proto,
-                            .rhs = body_block,
-                        },
-                    });
-                },
-                else => {
-                    // Since parseBlock only return error.ParseError on
-                    // a missing '}' we can assume this function was
-                    // supposed to end here.
-                    try p.warn(.expected_semi_or_lbrace);
-                    return null_node;
-                },
-            }
-        }
-        if (expect_fn) {
-            try p.warn(.expected_fn);
-            return error.ParseError;
-        }
-
-        const thread_local_token = p.eatToken(.keyword_threadlocal);
-        const var_decl = try p.parseVarDecl();
-        if (var_decl != 0) {
-            try p.expectSemicolon(.expected_semi_after_decl, false);
-            return var_decl;
-        }
-        if (thread_local_token != null) {
-            return p.fail(.expected_var_decl);
-        }
-        if (expect_var_or_fn) {
-            return p.fail(.expected_var_decl_or_fn);
-        }
-        if (p.token_tags[p.tok_i] != .keyword_usingnamespace) {
-            return p.fail(.expected_pub_item);
-        }
-        return p.expectUsingNamespace();
-    }
-
-    fn expectTopLevelDeclRecoverable(p: *Parser) error{OutOfMemory}!Node.Index {
-        return p.expectTopLevelDecl() catch |err| switch (err) {
-            error.OutOfMemory => return error.OutOfMemory,
-            error.ParseError => {
-                p.findNextContainerMember();
-                return null_node;
-            },
-        };
-    }
-
-    fn expectUsingNamespace(p: *Parser) !Node.Index {
-        const usingnamespace_token = p.assertToken(.keyword_usingnamespace);
-        const expr = try p.expectExpr();
-        try p.expectSemicolon(.expected_semi_after_decl, false);
-        return p.addNode(.{
-            .tag = .@"usingnamespace",
-            .main_token = usingnamespace_token,
-            .data = .{
-                .lhs = expr,
-                .rhs = undefined,
-            },
-        });
-    }
-
-    fn expectUsingNamespaceRecoverable(p: *Parser) error{OutOfMemory}!Node.Index {
-        return p.expectUsingNamespace() catch |err| switch (err) {
-            error.OutOfMemory => return error.OutOfMemory,
-            error.ParseError => {
-                p.findNextContainerMember();
-                return null_node;
-            },
-        };
-    }
-
-    /// FnProto <- KEYWORD_fn IDENTIFIER? LPAREN ParamDeclList RPAREN ByteAlign? AddrSpace? LinkSection? CallConv? EXCLAMATIONMARK? TypeExpr
-    fn parseFnProto(p: *Parser) !Node.Index {
-        const fn_token = p.eatToken(.keyword_fn) orelse return null_node;
-
-        // We want the fn proto node to be before its children in the array.
-        const fn_proto_index = try p.reserveNode(.fn_proto);
-        errdefer p.unreserveNode(fn_proto_index);
-
-        _ = p.eatToken(.identifier);
-        const params = try p.parseParamDeclList();
-        const align_expr = try p.parseByteAlign();
-        const addrspace_expr = try p.parseAddrSpace();
-        const section_expr = try p.parseLinkSection();
-        const callconv_expr = try p.parseCallconv();
-        _ = p.eatToken(.bang);
-
-        const return_type_expr = try p.parseTypeExpr();
-        if (return_type_expr == 0) {
-            // most likely the user forgot to specify the return type.
-            // Mark return type as invalid and try to continue.
-            try p.warn(.expected_return_type);
-        }
-
-        if (align_expr == 0 and section_expr == 0 and callconv_expr == 0 and addrspace_expr == 0) {
-            switch (params) {
-                .zero_or_one => |param| return p.setNode(fn_proto_index, .{
-                    .tag = .fn_proto_simple,
-                    .main_token = fn_token,
-                    .data = .{
-                        .lhs = param,
-                        .rhs = return_type_expr,
-                    },
-                }),
-                .multi => |span| {
-                    return p.setNode(fn_proto_index, .{
-                        .tag = .fn_proto_multi,
-                        .main_token = fn_token,
-                        .data = .{
-                            .lhs = try p.addExtra(Node.SubRange{
-                                .start = span.start,
-                                .end = span.end,
-                            }),
-                            .rhs = return_type_expr,
-                        },
-                    });
-                },
-            }
-        }
-        switch (params) {
-            .zero_or_one => |param| return p.setNode(fn_proto_index, .{
-                .tag = .fn_proto_one,
-                .main_token = fn_token,
-                .data = .{
-                    .lhs = try p.addExtra(Node.FnProtoOne{
-                        .param = param,
-                        .align_expr = align_expr,
-                        .addrspace_expr = addrspace_expr,
-                        .section_expr = section_expr,
-                        .callconv_expr = callconv_expr,
-                    }),
-                    .rhs = return_type_expr,
-                },
-            }),
-            .multi => |span| {
-                return p.setNode(fn_proto_index, .{
-                    .tag = .fn_proto,
-                    .main_token = fn_token,
-                    .data = .{
-                        .lhs = try p.addExtra(Node.FnProto{
-                            .params_start = span.start,
-                            .params_end = span.end,
-                            .align_expr = align_expr,
-                            .addrspace_expr = addrspace_expr,
-                            .section_expr = section_expr,
-                            .callconv_expr = callconv_expr,
-                        }),
-                        .rhs = return_type_expr,
-                    },
-                });
-            },
-        }
-    }
-
-    /// VarDecl <- (KEYWORD_const / KEYWORD_var) IDENTIFIER (COLON TypeExpr)? ByteAlign? AddrSpace? LinkSection? (EQUAL Expr)? SEMICOLON
-    fn parseVarDecl(p: *Parser) !Node.Index {
-        const mut_token = p.eatToken(.keyword_const) orelse
-            p.eatToken(.keyword_var) orelse
-            return null_node;
-
-        _ = try p.expectToken(.identifier);
-        const type_node: Node.Index = if (p.eatToken(.colon) == null) 0 else try p.expectTypeExpr();
-        const align_node = try p.parseByteAlign();
-        const addrspace_node = try p.parseAddrSpace();
-        const section_node = try p.parseLinkSection();
-        const init_node: Node.Index = switch (p.token_tags[p.tok_i]) {
-            .equal_equal => blk: {
-                try p.warn(.wrong_equal_var_decl);
-                p.tok_i += 1;
-                break :blk try p.expectExpr();
-            },
-            .equal => blk: {
-                p.tok_i += 1;
-                break :blk try p.expectExpr();
-            },
-            else => 0,
-        };
-        if (section_node == 0 and addrspace_node == 0) {
-            if (align_node == 0) {
-                return p.addNode(.{
-                    .tag = .simple_var_decl,
-                    .main_token = mut_token,
-                    .data = .{
-                        .lhs = type_node,
-                        .rhs = init_node,
-                    },
-                });
-            } else if (type_node == 0) {
-                return p.addNode(.{
-                    .tag = .aligned_var_decl,
-                    .main_token = mut_token,
-                    .data = .{
-                        .lhs = align_node,
-                        .rhs = init_node,
-                    },
-                });
-            } else {
-                return p.addNode(.{
-                    .tag = .local_var_decl,
-                    .main_token = mut_token,
-                    .data = .{
-                        .lhs = try p.addExtra(Node.LocalVarDecl{
-                            .type_node = type_node,
-                            .align_node = align_node,
-                        }),
-                        .rhs = init_node,
-                    },
-                });
-            }
-        } else {
-            return p.addNode(.{
-                .tag = .global_var_decl,
-                .main_token = mut_token,
-                .data = .{
-                    .lhs = try p.addExtra(Node.GlobalVarDecl{
-                        .type_node = type_node,
-                        .align_node = align_node,
-                        .addrspace_node = addrspace_node,
-                        .section_node = section_node,
-                    }),
-                    .rhs = init_node,
-                },
-            });
-        }
-    }
-
-    /// ContainerField
-    ///     <- doc_comment? KEYWORD_comptime? IDENTIFIER (COLON TypeExpr)? ByteAlign? (EQUAL Expr)?
-    ///      / doc_comment? KEYWORD_comptime? (IDENTIFIER COLON)? !KEYWORD_fn TypeExpr ByteAlign? (EQUAL Expr)?
-    fn expectContainerField(p: *Parser) !Node.Index {
-        var main_token = p.tok_i;
-        _ = p.eatToken(.keyword_comptime);
-        const tuple_like = p.token_tags[p.tok_i] != .identifier or p.token_tags[p.tok_i + 1] != .colon;
-        if (!tuple_like) {
-            main_token = p.assertToken(.identifier);
-        }
-
-        var align_expr: Node.Index = 0;
-        var type_expr: Node.Index = 0;
-        if (p.eatToken(.colon) != null or tuple_like) {
-            type_expr = try p.expectTypeExpr();
-            align_expr = try p.parseByteAlign();
-        }
-
-        const value_expr: Node.Index = if (p.eatToken(.equal) == null) 0 else try p.expectExpr();
-
-        if (align_expr == 0) {
-            return p.addNode(.{
-                .tag = .container_field_init,
-                .main_token = main_token,
-                .data = .{
-                    .lhs = type_expr,
-                    .rhs = value_expr,
-                },
-            });
-        } else if (value_expr == 0) {
-            return p.addNode(.{
-                .tag = .container_field_align,
-                .main_token = main_token,
-                .data = .{
-                    .lhs = type_expr,
-                    .rhs = align_expr,
-                },
-            });
-        } else {
-            return p.addNode(.{
-                .tag = .container_field,
-                .main_token = main_token,
-                .data = .{
-                    .lhs = type_expr,
-                    .rhs = try p.addExtra(Node.ContainerField{
-                        .value_expr = value_expr,
-                        .align_expr = align_expr,
-                    }),
-                },
-            });
-        }
-    }
-
-    /// Statement
-    ///     <- KEYWORD_comptime? VarDecl
-    ///      / KEYWORD_comptime BlockExprStatement
-    ///      / KEYWORD_nosuspend BlockExprStatement
-    ///      / KEYWORD_suspend BlockExprStatement
-    ///      / KEYWORD_defer BlockExprStatement
-    ///      / KEYWORD_errdefer Payload? BlockExprStatement
-    ///      / IfStatement
-    ///      / LabeledStatement
-    ///      / SwitchExpr
-    ///      / AssignExpr SEMICOLON
-    fn parseStatement(p: *Parser, allow_defer_var: bool) Error!Node.Index {
-        const comptime_token = p.eatToken(.keyword_comptime);
-
-        if (allow_defer_var) {
-            const var_decl = try p.parseVarDecl();
-            if (var_decl != 0) {
-                try p.expectSemicolon(.expected_semi_after_decl, true);
-                return var_decl;
-            }
-        }
-
-        if (comptime_token) |token| {
-            return p.addNode(.{
-                .tag = .@"comptime",
-                .main_token = token,
-                .data = .{
-                    .lhs = try p.expectBlockExprStatement(),
-                    .rhs = undefined,
-                },
-            });
-        }
-
-        switch (p.token_tags[p.tok_i]) {
-            .keyword_nosuspend => {
-                return p.addNode(.{
-                    .tag = .@"nosuspend",
-                    .main_token = p.nextToken(),
-                    .data = .{
-                        .lhs = try p.expectBlockExprStatement(),
-                        .rhs = undefined,
-                    },
-                });
-            },
-            .keyword_suspend => {
-                const token = p.nextToken();
-                const block_expr = try p.expectBlockExprStatement();
-                return p.addNode(.{
-                    .tag = .@"suspend",
-                    .main_token = token,
-                    .data = .{
-                        .lhs = block_expr,
-                        .rhs = undefined,
-                    },
-                });
-            },
-            .keyword_defer => if (allow_defer_var) return p.addNode(.{
-                .tag = .@"defer",
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = undefined,
-                    .rhs = try p.expectBlockExprStatement(),
-                },
-            }),
-            .keyword_errdefer => if (allow_defer_var) return p.addNode(.{
-                .tag = .@"errdefer",
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = try p.parsePayload(),
-                    .rhs = try p.expectBlockExprStatement(),
-                },
-            }),
-            .keyword_switch => return p.expectSwitchExpr(),
-            .keyword_if => return p.expectIfStatement(),
-            .keyword_enum, .keyword_struct, .keyword_union => {
-                const identifier = p.tok_i + 1;
-                if (try p.parseCStyleContainer()) {
-                    // Return something so that `expectStatement` is happy.
-                    return p.addNode(.{
-                        .tag = .identifier,
-                        .main_token = identifier,
-                        .data = .{
-                            .lhs = undefined,
-                            .rhs = undefined,
-                        },
-                    });
-                }
-            },
-            else => {},
-        }
-
-        const labeled_statement = try p.parseLabeledStatement();
-        if (labeled_statement != 0) return labeled_statement;
-
-        const assign_expr = try p.parseAssignExpr();
-        if (assign_expr != 0) {
-            try p.expectSemicolon(.expected_semi_after_stmt, true);
-            return assign_expr;
-        }
-
-        return null_node;
-    }
-
-    fn expectStatement(p: *Parser, allow_defer_var: bool) !Node.Index {
-        const statement = try p.parseStatement(allow_defer_var);
-        if (statement == 0) {
-            return p.fail(.expected_statement);
-        }
-        return statement;
-    }
-
-    /// If a parse error occurs, reports an error, but then finds the next statement
-    /// and returns that one instead. If a parse error occurs but there is no following
-    /// statement, returns 0.
-    fn expectStatementRecoverable(p: *Parser) Error!Node.Index {
-        while (true) {
-            return p.expectStatement(true) catch |err| switch (err) {
-                error.OutOfMemory => return error.OutOfMemory,
-                error.ParseError => {
-                    p.findNextStmt(); // Try to skip to the next statement.
-                    switch (p.token_tags[p.tok_i]) {
-                        .r_brace => return null_node,
-                        .eof => return error.ParseError,
-                        else => continue,
-                    }
-                },
-            };
-        }
-    }
-
-    /// IfStatement
-    ///     <- IfPrefix BlockExpr ( KEYWORD_else Payload? Statement )?
-    ///      / IfPrefix AssignExpr ( SEMICOLON / KEYWORD_else Payload? Statement )
-    fn expectIfStatement(p: *Parser) !Node.Index {
-        const if_token = p.assertToken(.keyword_if);
-        _ = try p.expectToken(.l_paren);
-        const condition = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        _ = try p.parsePtrPayload();
-
-        // TODO propose to change the syntax so that semicolons are always required
-        // inside if statements, even if there is an `else`.
-        var else_required = false;
-        const then_expr = blk: {
-            const block_expr = try p.parseBlockExpr();
-            if (block_expr != 0) break :blk block_expr;
-            const assign_expr = try p.parseAssignExpr();
-            if (assign_expr == 0) {
-                return p.fail(.expected_block_or_assignment);
-            }
-            if (p.eatToken(.semicolon)) |_| {
-                return p.addNode(.{
-                    .tag = .if_simple,
-                    .main_token = if_token,
-                    .data = .{
-                        .lhs = condition,
-                        .rhs = assign_expr,
-                    },
-                });
-            }
-            else_required = true;
-            break :blk assign_expr;
-        };
-        _ = p.eatToken(.keyword_else) orelse {
-            if (else_required) {
-                try p.warn(.expected_semi_or_else);
-            }
-            return p.addNode(.{
-                .tag = .if_simple,
-                .main_token = if_token,
-                .data = .{
-                    .lhs = condition,
-                    .rhs = then_expr,
-                },
-            });
-        };
-        _ = try p.parsePayload();
-        const else_expr = try p.expectStatement(false);
-        return p.addNode(.{
-            .tag = .@"if",
-            .main_token = if_token,
-            .data = .{
-                .lhs = condition,
-                .rhs = try p.addExtra(Node.If{
-                    .then_expr = then_expr,
-                    .else_expr = else_expr,
-                }),
-            },
-        });
-    }
-
-    /// LabeledStatement <- BlockLabel? (Block / LoopStatement)
-    fn parseLabeledStatement(p: *Parser) !Node.Index {
-        const label_token = p.parseBlockLabel();
-        const block = try p.parseBlock();
-        if (block != 0) return block;
-
-        const loop_stmt = try p.parseLoopStatement();
-        if (loop_stmt != 0) return loop_stmt;
-
-        if (label_token != 0) {
-            const after_colon = p.tok_i;
-            const node = try p.parseTypeExpr();
-            if (node != 0) {
-                const a = try p.parseByteAlign();
-                const b = try p.parseAddrSpace();
-                const c = try p.parseLinkSection();
-                const d = if (p.eatToken(.equal) == null) 0 else try p.expectExpr();
-                if (a != 0 or b != 0 or c != 0 or d != 0) {
-                    return p.failMsg(.{ .tag = .expected_var_const, .token = label_token });
-                }
-            }
-            return p.failMsg(.{ .tag = .expected_labelable, .token = after_colon });
-        }
-
-        return null_node;
-    }
-
-    /// LoopStatement <- KEYWORD_inline? (ForStatement / WhileStatement)
-    fn parseLoopStatement(p: *Parser) !Node.Index {
-        const inline_token = p.eatToken(.keyword_inline);
-
-        const for_statement = try p.parseForStatement();
-        if (for_statement != 0) return for_statement;
-
-        const while_statement = try p.parseWhileStatement();
-        if (while_statement != 0) return while_statement;
-
-        if (inline_token == null) return null_node;
-
-        // If we've seen "inline", there should have been a "for" or "while"
-        return p.fail(.expected_inlinable);
-    }
-
-    /// ForPrefix <- KEYWORD_for LPAREN Expr RPAREN PtrIndexPayload
-    ///
-    /// ForStatement
-    ///     <- ForPrefix BlockExpr ( KEYWORD_else Statement )?
-    ///      / ForPrefix AssignExpr ( SEMICOLON / KEYWORD_else Statement )
-    fn parseForStatement(p: *Parser) !Node.Index {
-        const for_token = p.eatToken(.keyword_for) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const array_expr = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        const found_payload = try p.parsePtrIndexPayload();
-        if (found_payload == 0) try p.warn(.expected_loop_payload);
-
-        // TODO propose to change the syntax so that semicolons are always required
-        // inside while statements, even if there is an `else`.
-        var else_required = false;
-        const then_expr = blk: {
-            const block_expr = try p.parseBlockExpr();
-            if (block_expr != 0) break :blk block_expr;
-            const assign_expr = try p.parseAssignExpr();
-            if (assign_expr == 0) {
-                return p.fail(.expected_block_or_assignment);
-            }
-            if (p.eatToken(.semicolon)) |_| {
-                return p.addNode(.{
-                    .tag = .for_simple,
-                    .main_token = for_token,
-                    .data = .{
-                        .lhs = array_expr,
-                        .rhs = assign_expr,
-                    },
-                });
-            }
-            else_required = true;
-            break :blk assign_expr;
-        };
-        _ = p.eatToken(.keyword_else) orelse {
-            if (else_required) {
-                try p.warn(.expected_semi_or_else);
-            }
-            return p.addNode(.{
-                .tag = .for_simple,
-                .main_token = for_token,
-                .data = .{
-                    .lhs = array_expr,
-                    .rhs = then_expr,
-                },
-            });
-        };
-        return p.addNode(.{
-            .tag = .@"for",
-            .main_token = for_token,
-            .data = .{
-                .lhs = array_expr,
-                .rhs = try p.addExtra(Node.If{
-                    .then_expr = then_expr,
-                    .else_expr = try p.expectStatement(false),
-                }),
-            },
-        });
-    }
-
-    /// WhilePrefix <- KEYWORD_while LPAREN Expr RPAREN PtrPayload? WhileContinueExpr?
-    ///
-    /// WhileStatement
-    ///     <- WhilePrefix BlockExpr ( KEYWORD_else Payload? Statement )?
-    ///      / WhilePrefix AssignExpr ( SEMICOLON / KEYWORD_else Payload? Statement )
-    fn parseWhileStatement(p: *Parser) !Node.Index {
-        const while_token = p.eatToken(.keyword_while) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const condition = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        _ = try p.parsePtrPayload();
-        const cont_expr = try p.parseWhileContinueExpr();
-
-        // TODO propose to change the syntax so that semicolons are always required
-        // inside while statements, even if there is an `else`.
-        var else_required = false;
-        const then_expr = blk: {
-            const block_expr = try p.parseBlockExpr();
-            if (block_expr != 0) break :blk block_expr;
-            const assign_expr = try p.parseAssignExpr();
-            if (assign_expr == 0) {
-                return p.fail(.expected_block_or_assignment);
-            }
-            if (p.eatToken(.semicolon)) |_| {
-                if (cont_expr == 0) {
-                    return p.addNode(.{
-                        .tag = .while_simple,
-                        .main_token = while_token,
-                        .data = .{
-                            .lhs = condition,
-                            .rhs = assign_expr,
-                        },
-                    });
-                } else {
-                    return p.addNode(.{
-                        .tag = .while_cont,
-                        .main_token = while_token,
-                        .data = .{
-                            .lhs = condition,
-                            .rhs = try p.addExtra(Node.WhileCont{
-                                .cont_expr = cont_expr,
-                                .then_expr = assign_expr,
-                            }),
-                        },
-                    });
-                }
-            }
-            else_required = true;
-            break :blk assign_expr;
-        };
-        _ = p.eatToken(.keyword_else) orelse {
-            if (else_required) {
-                try p.warn(.expected_semi_or_else);
-            }
-            if (cont_expr == 0) {
-                return p.addNode(.{
-                    .tag = .while_simple,
-                    .main_token = while_token,
-                    .data = .{
-                        .lhs = condition,
-                        .rhs = then_expr,
-                    },
-                });
-            } else {
-                return p.addNode(.{
-                    .tag = .while_cont,
-                    .main_token = while_token,
-                    .data = .{
-                        .lhs = condition,
-                        .rhs = try p.addExtra(Node.WhileCont{
-                            .cont_expr = cont_expr,
-                            .then_expr = then_expr,
-                        }),
-                    },
-                });
-            }
-        };
-        _ = try p.parsePayload();
-        const else_expr = try p.expectStatement(false);
-        return p.addNode(.{
-            .tag = .@"while",
-            .main_token = while_token,
-            .data = .{
-                .lhs = condition,
-                .rhs = try p.addExtra(Node.While{
-                    .cont_expr = cont_expr,
-                    .then_expr = then_expr,
-                    .else_expr = else_expr,
-                }),
-            },
-        });
-    }
-
-    /// BlockExprStatement
-    ///     <- BlockExpr
-    ///      / AssignExpr SEMICOLON
-    fn parseBlockExprStatement(p: *Parser) !Node.Index {
-        const block_expr = try p.parseBlockExpr();
-        if (block_expr != 0) {
-            return block_expr;
-        }
-        const assign_expr = try p.parseAssignExpr();
-        if (assign_expr != 0) {
-            try p.expectSemicolon(.expected_semi_after_stmt, true);
-            return assign_expr;
-        }
-        return null_node;
-    }
-
-    fn expectBlockExprStatement(p: *Parser) !Node.Index {
-        const node = try p.parseBlockExprStatement();
-        if (node == 0) {
-            return p.fail(.expected_block_or_expr);
-        }
-        return node;
-    }
-
-    /// BlockExpr <- BlockLabel? Block
-    fn parseBlockExpr(p: *Parser) Error!Node.Index {
-        switch (p.token_tags[p.tok_i]) {
-            .identifier => {
-                if (p.token_tags[p.tok_i + 1] == .colon and
-                    p.token_tags[p.tok_i + 2] == .l_brace)
-                {
-                    p.tok_i += 2;
-                    return p.parseBlock();
-                } else {
-                    return null_node;
-                }
-            },
-            .l_brace => return p.parseBlock(),
-            else => return null_node,
-        }
-    }
-
-    /// AssignExpr <- Expr (AssignOp Expr)?
-    ///
-    /// AssignOp
-    ///     <- ASTERISKEQUAL
-    ///      / ASTERISKPIPEEQUAL
-    ///      / SLASHEQUAL
-    ///      / PERCENTEQUAL
-    ///      / PLUSEQUAL
-    ///      / PLUSPIPEEQUAL
-    ///      / MINUSEQUAL
-    ///      / MINUSPIPEEQUAL
-    ///      / LARROW2EQUAL
-    ///      / LARROW2PIPEEQUAL
-    ///      / RARROW2EQUAL
-    ///      / AMPERSANDEQUAL
-    ///      / CARETEQUAL
-    ///      / PIPEEQUAL
-    ///      / ASTERISKPERCENTEQUAL
-    ///      / PLUSPERCENTEQUAL
-    ///      / MINUSPERCENTEQUAL
-    ///      / EQUAL
-    fn parseAssignExpr(p: *Parser) !Node.Index {
-        const expr = try p.parseExpr();
-        if (expr == 0) return null_node;
-
-        const tag: Node.Tag = switch (p.token_tags[p.tok_i]) {
-            .asterisk_equal => .assign_mul,
-            .slash_equal => .assign_div,
-            .percent_equal => .assign_mod,
-            .plus_equal => .assign_add,
-            .minus_equal => .assign_sub,
-            .angle_bracket_angle_bracket_left_equal => .assign_shl,
-            .angle_bracket_angle_bracket_left_pipe_equal => .assign_shl_sat,
-            .angle_bracket_angle_bracket_right_equal => .assign_shr,
-            .ampersand_equal => .assign_bit_and,
-            .caret_equal => .assign_bit_xor,
-            .pipe_equal => .assign_bit_or,
-            .asterisk_percent_equal => .assign_mul_wrap,
-            .plus_percent_equal => .assign_add_wrap,
-            .minus_percent_equal => .assign_sub_wrap,
-            .asterisk_pipe_equal => .assign_mul_sat,
-            .plus_pipe_equal => .assign_add_sat,
-            .minus_pipe_equal => .assign_sub_sat,
-            .equal => .assign,
-            else => return expr,
-        };
-        return p.addNode(.{
-            .tag = tag,
-            .main_token = p.nextToken(),
-            .data = .{
-                .lhs = expr,
-                .rhs = try p.expectExpr(),
-            },
-        });
-    }
-
-    fn expectAssignExpr(p: *Parser) !Node.Index {
-        const expr = try p.parseAssignExpr();
-        if (expr == 0) {
-            return p.fail(.expected_expr_or_assignment);
-        }
-        return expr;
-    }
-
-    fn parseExpr(p: *Parser) Error!Node.Index {
-        return p.parseExprPrecedence(0);
-    }
-
-    fn expectExpr(p: *Parser) Error!Node.Index {
-        const node = try p.parseExpr();
-        if (node == 0) {
-            return p.fail(.expected_expr);
-        } else {
-            return node;
-        }
-    }
-
-    const Assoc = enum {
-        left,
-        none,
-    };
-
-    const OperInfo = struct {
-        prec: i8,
-        tag: Node.Tag,
-        assoc: Assoc = Assoc.left,
-    };
-
-    // A table of binary operator information. Higher precedence numbers are
-    // stickier. All operators at the same precedence level should have the same
-    // associativity.
-    const operTable = std.enums.directEnumArrayDefault(Token.Tag, OperInfo, .{ .prec = -1, .tag = Node.Tag.root }, 0, .{
-        .keyword_or = .{ .prec = 10, .tag = .bool_or },
-
-        .keyword_and = .{ .prec = 20, .tag = .bool_and },
-
-        .equal_equal = .{ .prec = 30, .tag = .equal_equal, .assoc = Assoc.none },
-        .bang_equal = .{ .prec = 30, .tag = .bang_equal, .assoc = Assoc.none },
-        .angle_bracket_left = .{ .prec = 30, .tag = .less_than, .assoc = Assoc.none },
-        .angle_bracket_right = .{ .prec = 30, .tag = .greater_than, .assoc = Assoc.none },
-        .angle_bracket_left_equal = .{ .prec = 30, .tag = .less_or_equal, .assoc = Assoc.none },
-        .angle_bracket_right_equal = .{ .prec = 30, .tag = .greater_or_equal, .assoc = Assoc.none },
-
-        .ampersand = .{ .prec = 40, .tag = .bit_and },
-        .caret = .{ .prec = 40, .tag = .bit_xor },
-        .pipe = .{ .prec = 40, .tag = .bit_or },
-        .keyword_orelse = .{ .prec = 40, .tag = .@"orelse" },
-        .keyword_catch = .{ .prec = 40, .tag = .@"catch" },
-
-        .angle_bracket_angle_bracket_left = .{ .prec = 50, .tag = .shl },
-        .angle_bracket_angle_bracket_left_pipe = .{ .prec = 50, .tag = .shl_sat },
-        .angle_bracket_angle_bracket_right = .{ .prec = 50, .tag = .shr },
-
-        .plus = .{ .prec = 60, .tag = .add },
-        .minus = .{ .prec = 60, .tag = .sub },
-        .plus_plus = .{ .prec = 60, .tag = .array_cat },
-        .plus_percent = .{ .prec = 60, .tag = .add_wrap },
-        .minus_percent = .{ .prec = 60, .tag = .sub_wrap },
-        .plus_pipe = .{ .prec = 60, .tag = .add_sat },
-        .minus_pipe = .{ .prec = 60, .tag = .sub_sat },
-
-        .pipe_pipe = .{ .prec = 70, .tag = .merge_error_sets },
-        .asterisk = .{ .prec = 70, .tag = .mul },
-        .slash = .{ .prec = 70, .tag = .div },
-        .percent = .{ .prec = 70, .tag = .mod },
-        .asterisk_asterisk = .{ .prec = 70, .tag = .array_mult },
-        .asterisk_percent = .{ .prec = 70, .tag = .mul_wrap },
-        .asterisk_pipe = .{ .prec = 70, .tag = .mul_sat },
-    });
-
-    fn parseExprPrecedence(p: *Parser, min_prec: i32) Error!Node.Index {
-        assert(min_prec >= 0);
-        var node = try p.parsePrefixExpr();
-        if (node == 0) {
-            return null_node;
-        }
-
-        var banned_prec: i8 = -1;
-
-        while (true) {
-            const tok_tag = p.token_tags[p.tok_i];
-            const info = operTable[@intCast(usize, @enumToInt(tok_tag))];
-            if (info.prec < min_prec) {
-                break;
-            }
-            if (info.prec == banned_prec) {
-                return p.fail(.chained_comparison_operators);
-            }
-
-            const oper_token = p.nextToken();
-            // Special-case handling for "catch"
-            if (tok_tag == .keyword_catch) {
-                _ = try p.parsePayload();
-            }
-            const rhs = try p.parseExprPrecedence(info.prec + 1);
-            if (rhs == 0) {
-                try p.warn(.expected_expr);
-                return node;
-            }
-
-            {
-                const tok_len = tok_tag.lexeme().?.len;
-                const char_before = p.source[p.token_starts[oper_token] - 1];
-                const char_after = p.source[p.token_starts[oper_token] + tok_len];
-                if (tok_tag == .ampersand and char_after == '&') {
-                    // without types we don't know if '&&' was intended as 'bitwise_and address_of', or a c-style logical_and
-                    // The best the parser can do is recommend changing it to 'and' or ' & &'
-                    try p.warnMsg(.{ .tag = .invalid_ampersand_ampersand, .token = oper_token });
-                } else if (std.ascii.isWhitespace(char_before) != std.ascii.isWhitespace(char_after)) {
-                    try p.warnMsg(.{ .tag = .mismatched_binary_op_whitespace, .token = oper_token });
-                }
-            }
-
-            node = try p.addNode(.{
-                .tag = info.tag,
-                .main_token = oper_token,
-                .data = .{
-                    .lhs = node,
-                    .rhs = rhs,
-                },
-            });
-
-            if (info.assoc == Assoc.none) {
-                banned_prec = info.prec;
-            }
-        }
-
-        return node;
-    }
-
-    /// PrefixExpr <- PrefixOp* PrimaryExpr
-    ///
-    /// PrefixOp
-    ///     <- EXCLAMATIONMARK
-    ///      / MINUS
-    ///      / TILDE
-    ///      / MINUSPERCENT
-    ///      / AMPERSAND
-    ///      / KEYWORD_try
-    ///      / KEYWORD_await
-    fn parsePrefixExpr(p: *Parser) Error!Node.Index {
-        const tag: Node.Tag = switch (p.token_tags[p.tok_i]) {
-            .bang => .bool_not,
-            .minus => .negation,
-            .tilde => .bit_not,
-            .minus_percent => .negation_wrap,
-            .ampersand => .address_of,
-            .keyword_try => .@"try",
-            .keyword_await => .@"await",
-            else => return p.parsePrimaryExpr(),
-        };
-        return p.addNode(.{
-            .tag = tag,
-            .main_token = p.nextToken(),
-            .data = .{
-                .lhs = try p.expectPrefixExpr(),
-                .rhs = undefined,
-            },
-        });
-    }
-
-    fn expectPrefixExpr(p: *Parser) Error!Node.Index {
-        const node = try p.parsePrefixExpr();
-        if (node == 0) {
-            return p.fail(.expected_prefix_expr);
-        }
-        return node;
-    }
-
-    /// TypeExpr <- PrefixTypeOp* ErrorUnionExpr
-    ///
-    /// PrefixTypeOp
-    ///     <- QUESTIONMARK
-    ///      / KEYWORD_anyframe MINUSRARROW
-    ///      / SliceTypeStart (ByteAlign / AddrSpace / KEYWORD_const / KEYWORD_volatile / KEYWORD_allowzero)*
-    ///      / PtrTypeStart (AddrSpace / KEYWORD_align LPAREN Expr (COLON Expr COLON Expr)? RPAREN / KEYWORD_const / KEYWORD_volatile / KEYWORD_allowzero)*
-    ///      / ArrayTypeStart
-    ///
-    /// SliceTypeStart <- LBRACKET (COLON Expr)? RBRACKET
-    ///
-    /// PtrTypeStart
-    ///     <- ASTERISK
-    ///      / ASTERISK2
-    ///      / LBRACKET ASTERISK (LETTERC / COLON Expr)? RBRACKET
-    ///
-    /// ArrayTypeStart <- LBRACKET Expr (COLON Expr)? RBRACKET
-    fn parseTypeExpr(p: *Parser) Error!Node.Index {
-        switch (p.token_tags[p.tok_i]) {
-            .question_mark => return p.addNode(.{
-                .tag = .optional_type,
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = try p.expectTypeExpr(),
-                    .rhs = undefined,
-                },
-            }),
-            .keyword_anyframe => switch (p.token_tags[p.tok_i + 1]) {
-                .arrow => return p.addNode(.{
-                    .tag = .anyframe_type,
-                    .main_token = p.nextToken(),
-                    .data = .{
-                        .lhs = p.nextToken(),
-                        .rhs = try p.expectTypeExpr(),
-                    },
-                }),
-                else => return p.parseErrorUnionExpr(),
-            },
-            .asterisk => {
-                const asterisk = p.nextToken();
-                const mods = try p.parsePtrModifiers();
-                const elem_type = try p.expectTypeExpr();
-                if (mods.bit_range_start != 0) {
-                    return p.addNode(.{
-                        .tag = .ptr_type_bit_range,
-                        .main_token = asterisk,
-                        .data = .{
-                            .lhs = try p.addExtra(Node.PtrTypeBitRange{
-                                .sentinel = 0,
-                                .align_node = mods.align_node,
-                                .addrspace_node = mods.addrspace_node,
-                                .bit_range_start = mods.bit_range_start,
-                                .bit_range_end = mods.bit_range_end,
-                            }),
-                            .rhs = elem_type,
-                        },
-                    });
-                } else if (mods.addrspace_node != 0) {
-                    return p.addNode(.{
-                        .tag = .ptr_type,
-                        .main_token = asterisk,
-                        .data = .{
-                            .lhs = try p.addExtra(Node.PtrType{
-                                .sentinel = 0,
-                                .align_node = mods.align_node,
-                                .addrspace_node = mods.addrspace_node,
-                            }),
-                            .rhs = elem_type,
-                        },
-                    });
-                } else {
-                    return p.addNode(.{
-                        .tag = .ptr_type_aligned,
-                        .main_token = asterisk,
-                        .data = .{
-                            .lhs = mods.align_node,
-                            .rhs = elem_type,
-                        },
-                    });
-                }
-            },
-            .asterisk_asterisk => {
-                const asterisk = p.nextToken();
-                const mods = try p.parsePtrModifiers();
-                const elem_type = try p.expectTypeExpr();
-                const inner: Node.Index = inner: {
-                    if (mods.bit_range_start != 0) {
-                        break :inner try p.addNode(.{
-                            .tag = .ptr_type_bit_range,
-                            .main_token = asterisk,
-                            .data = .{
-                                .lhs = try p.addExtra(Node.PtrTypeBitRange{
-                                    .sentinel = 0,
-                                    .align_node = mods.align_node,
-                                    .addrspace_node = mods.addrspace_node,
-                                    .bit_range_start = mods.bit_range_start,
-                                    .bit_range_end = mods.bit_range_end,
-                                }),
-                                .rhs = elem_type,
-                            },
-                        });
-                    } else if (mods.addrspace_node != 0) {
-                        break :inner try p.addNode(.{
-                            .tag = .ptr_type,
-                            .main_token = asterisk,
-                            .data = .{
-                                .lhs = try p.addExtra(Node.PtrType{
-                                    .sentinel = 0,
-                                    .align_node = mods.align_node,
-                                    .addrspace_node = mods.addrspace_node,
-                                }),
-                                .rhs = elem_type,
-                            },
-                        });
-                    } else {
-                        break :inner try p.addNode(.{
-                            .tag = .ptr_type_aligned,
-                            .main_token = asterisk,
-                            .data = .{
-                                .lhs = mods.align_node,
-                                .rhs = elem_type,
-                            },
-                        });
-                    }
-                };
-                return p.addNode(.{
-                    .tag = .ptr_type_aligned,
-                    .main_token = asterisk,
-                    .data = .{
-                        .lhs = 0,
-                        .rhs = inner,
-                    },
-                });
-            },
-            .l_bracket => switch (p.token_tags[p.tok_i + 1]) {
-                .asterisk => {
-                    _ = p.nextToken();
-                    const asterisk = p.nextToken();
-                    var sentinel: Node.Index = 0;
-                    if (p.eatToken(.identifier)) |ident| {
-                        const ident_slice = p.source[p.token_starts[ident]..p.token_starts[ident + 1]];
-                        if (!std.mem.eql(u8, std.mem.trimRight(u8, ident_slice, &std.ascii.whitespace), "c")) {
-                            p.tok_i -= 1;
-                        }
-                    } else if (p.eatToken(.colon)) |_| {
-                        sentinel = try p.expectExpr();
-                    }
-                    _ = try p.expectToken(.r_bracket);
-                    const mods = try p.parsePtrModifiers();
-                    const elem_type = try p.expectTypeExpr();
-                    if (mods.bit_range_start == 0) {
-                        if (sentinel == 0 and mods.addrspace_node == 0) {
-                            return p.addNode(.{
-                                .tag = .ptr_type_aligned,
-                                .main_token = asterisk,
-                                .data = .{
-                                    .lhs = mods.align_node,
-                                    .rhs = elem_type,
-                                },
-                            });
-                        } else if (mods.align_node == 0 and mods.addrspace_node == 0) {
-                            return p.addNode(.{
-                                .tag = .ptr_type_sentinel,
-                                .main_token = asterisk,
-                                .data = .{
-                                    .lhs = sentinel,
-                                    .rhs = elem_type,
-                                },
-                            });
-                        } else {
-                            return p.addNode(.{
-                                .tag = .ptr_type,
-                                .main_token = asterisk,
-                                .data = .{
-                                    .lhs = try p.addExtra(Node.PtrType{
-                                        .sentinel = sentinel,
-                                        .align_node = mods.align_node,
-                                        .addrspace_node = mods.addrspace_node,
-                                    }),
-                                    .rhs = elem_type,
-                                },
-                            });
-                        }
-                    } else {
-                        return p.addNode(.{
-                            .tag = .ptr_type_bit_range,
-                            .main_token = asterisk,
-                            .data = .{
-                                .lhs = try p.addExtra(Node.PtrTypeBitRange{
-                                    .sentinel = sentinel,
-                                    .align_node = mods.align_node,
-                                    .addrspace_node = mods.addrspace_node,
-                                    .bit_range_start = mods.bit_range_start,
-                                    .bit_range_end = mods.bit_range_end,
-                                }),
-                                .rhs = elem_type,
-                            },
-                        });
-                    }
-                },
-                else => {
-                    const lbracket = p.nextToken();
-                    const len_expr = try p.parseExpr();
-                    const sentinel: Node.Index = if (p.eatToken(.colon)) |_|
-                        try p.expectExpr()
-                    else
-                        0;
-                    _ = try p.expectToken(.r_bracket);
-                    if (len_expr == 0) {
-                        const mods = try p.parsePtrModifiers();
-                        const elem_type = try p.expectTypeExpr();
-                        if (mods.bit_range_start != 0) {
-                            try p.warnMsg(.{
-                                .tag = .invalid_bit_range,
-                                .token = p.nodes.items(.main_token)[mods.bit_range_start],
-                            });
-                        }
-                        if (sentinel == 0 and mods.addrspace_node == 0) {
-                            return p.addNode(.{
-                                .tag = .ptr_type_aligned,
-                                .main_token = lbracket,
-                                .data = .{
-                                    .lhs = mods.align_node,
-                                    .rhs = elem_type,
-                                },
-                            });
-                        } else if (mods.align_node == 0 and mods.addrspace_node == 0) {
-                            return p.addNode(.{
-                                .tag = .ptr_type_sentinel,
-                                .main_token = lbracket,
-                                .data = .{
-                                    .lhs = sentinel,
-                                    .rhs = elem_type,
-                                },
-                            });
-                        } else {
-                            return p.addNode(.{
-                                .tag = .ptr_type,
-                                .main_token = lbracket,
-                                .data = .{
-                                    .lhs = try p.addExtra(Node.PtrType{
-                                        .sentinel = sentinel,
-                                        .align_node = mods.align_node,
-                                        .addrspace_node = mods.addrspace_node,
-                                    }),
-                                    .rhs = elem_type,
-                                },
-                            });
-                        }
-                    } else {
-                        switch (p.token_tags[p.tok_i]) {
-                            .keyword_align,
-                            .keyword_const,
-                            .keyword_volatile,
-                            .keyword_allowzero,
-                            .keyword_addrspace,
-                            => return p.fail(.ptr_mod_on_array_child_type),
-                            else => {},
-                        }
-                        const elem_type = try p.expectTypeExpr();
-                        if (sentinel == 0) {
-                            return p.addNode(.{
-                                .tag = .array_type,
-                                .main_token = lbracket,
-                                .data = .{
-                                    .lhs = len_expr,
-                                    .rhs = elem_type,
-                                },
-                            });
-                        } else {
-                            return p.addNode(.{
-                                .tag = .array_type_sentinel,
-                                .main_token = lbracket,
-                                .data = .{
-                                    .lhs = len_expr,
-                                    .rhs = try p.addExtra(.{
-                                        .elem_type = elem_type,
-                                        .sentinel = sentinel,
-                                    }),
-                                },
-                            });
-                        }
-                    }
-                },
-            },
-            else => return p.parseErrorUnionExpr(),
-        }
-    }
-
-    fn expectTypeExpr(p: *Parser) Error!Node.Index {
-        const node = try p.parseTypeExpr();
-        if (node == 0) {
-            return p.fail(.expected_type_expr);
-        }
-        return node;
-    }
-
-    /// PrimaryExpr
-    ///     <- AsmExpr
-    ///      / IfExpr
-    ///      / KEYWORD_break BreakLabel? Expr?
-    ///      / KEYWORD_comptime Expr
-    ///      / KEYWORD_nosuspend Expr
-    ///      / KEYWORD_continue BreakLabel?
-    ///      / KEYWORD_resume Expr
-    ///      / KEYWORD_return Expr?
-    ///      / BlockLabel? LoopExpr
-    ///      / Block
-    ///      / CurlySuffixExpr
-    fn parsePrimaryExpr(p: *Parser) !Node.Index {
-        switch (p.token_tags[p.tok_i]) {
-            .keyword_asm => return p.expectAsmExpr(),
-            .keyword_if => return p.parseIfExpr(),
-            .keyword_break => {
-                p.tok_i += 1;
-                return p.addNode(.{
-                    .tag = .@"break",
-                    .main_token = p.tok_i - 1,
-                    .data = .{
-                        .lhs = try p.parseBreakLabel(),
-                        .rhs = try p.parseExpr(),
-                    },
-                });
-            },
-            .keyword_continue => {
-                p.tok_i += 1;
-                return p.addNode(.{
-                    .tag = .@"continue",
-                    .main_token = p.tok_i - 1,
-                    .data = .{
-                        .lhs = try p.parseBreakLabel(),
-                        .rhs = undefined,
-                    },
-                });
-            },
-            .keyword_comptime => {
-                p.tok_i += 1;
-                return p.addNode(.{
-                    .tag = .@"comptime",
-                    .main_token = p.tok_i - 1,
-                    .data = .{
-                        .lhs = try p.expectExpr(),
-                        .rhs = undefined,
-                    },
-                });
-            },
-            .keyword_nosuspend => {
-                p.tok_i += 1;
-                return p.addNode(.{
-                    .tag = .@"nosuspend",
-                    .main_token = p.tok_i - 1,
-                    .data = .{
-                        .lhs = try p.expectExpr(),
-                        .rhs = undefined,
-                    },
-                });
-            },
-            .keyword_resume => {
-                p.tok_i += 1;
-                return p.addNode(.{
-                    .tag = .@"resume",
-                    .main_token = p.tok_i - 1,
-                    .data = .{
-                        .lhs = try p.expectExpr(),
-                        .rhs = undefined,
-                    },
-                });
-            },
-            .keyword_return => {
-                p.tok_i += 1;
-                return p.addNode(.{
-                    .tag = .@"return",
-                    .main_token = p.tok_i - 1,
-                    .data = .{
-                        .lhs = try p.parseExpr(),
-                        .rhs = undefined,
-                    },
-                });
-            },
-            .identifier => {
-                if (p.token_tags[p.tok_i + 1] == .colon) {
-                    switch (p.token_tags[p.tok_i + 2]) {
-                        .keyword_inline => {
-                            p.tok_i += 3;
-                            switch (p.token_tags[p.tok_i]) {
-                                .keyword_for => return p.parseForExpr(),
-                                .keyword_while => return p.parseWhileExpr(),
-                                else => return p.fail(.expected_inlinable),
-                            }
-                        },
-                        .keyword_for => {
-                            p.tok_i += 2;
-                            return p.parseForExpr();
-                        },
-                        .keyword_while => {
-                            p.tok_i += 2;
-                            return p.parseWhileExpr();
-                        },
-                        .l_brace => {
-                            p.tok_i += 2;
-                            return p.parseBlock();
-                        },
-                        else => return p.parseCurlySuffixExpr(),
-                    }
-                } else {
-                    return p.parseCurlySuffixExpr();
-                }
-            },
-            .keyword_inline => {
-                p.tok_i += 1;
-                switch (p.token_tags[p.tok_i]) {
-                    .keyword_for => return p.parseForExpr(),
-                    .keyword_while => return p.parseWhileExpr(),
-                    else => return p.fail(.expected_inlinable),
-                }
-            },
-            .keyword_for => return p.parseForExpr(),
-            .keyword_while => return p.parseWhileExpr(),
-            .l_brace => return p.parseBlock(),
-            else => return p.parseCurlySuffixExpr(),
-        }
-    }
-
-    /// IfExpr <- IfPrefix Expr (KEYWORD_else Payload? Expr)?
-    fn parseIfExpr(p: *Parser) !Node.Index {
-        return p.parseIf(expectExpr);
-    }
-
-    /// Block <- LBRACE Statement* RBRACE
-    fn parseBlock(p: *Parser) !Node.Index {
-        const lbrace = p.eatToken(.l_brace) orelse return null_node;
-        const scratch_top = p.scratch.items.len;
-        defer p.scratch.shrinkRetainingCapacity(scratch_top);
-        while (true) {
-            if (p.token_tags[p.tok_i] == .r_brace) break;
-            const statement = try p.expectStatementRecoverable();
-            if (statement == 0) break;
-            try p.scratch.append(p.gpa, statement);
-        }
-        _ = try p.expectToken(.r_brace);
-        const semicolon = (p.token_tags[p.tok_i - 2] == .semicolon);
-        const statements = p.scratch.items[scratch_top..];
-        switch (statements.len) {
-            0 => return p.addNode(.{
-                .tag = .block_two,
-                .main_token = lbrace,
-                .data = .{
-                    .lhs = 0,
-                    .rhs = 0,
-                },
-            }),
-            1 => return p.addNode(.{
-                .tag = if (semicolon) .block_two_semicolon else .block_two,
-                .main_token = lbrace,
-                .data = .{
-                    .lhs = statements[0],
-                    .rhs = 0,
-                },
-            }),
-            2 => return p.addNode(.{
-                .tag = if (semicolon) .block_two_semicolon else .block_two,
-                .main_token = lbrace,
-                .data = .{
-                    .lhs = statements[0],
-                    .rhs = statements[1],
-                },
-            }),
-            else => {
-                const span = try p.listToSpan(statements);
-                return p.addNode(.{
-                    .tag = if (semicolon) .block_semicolon else .block,
-                    .main_token = lbrace,
-                    .data = .{
-                        .lhs = span.start,
-                        .rhs = span.end,
-                    },
-                });
-            },
-        }
-    }
-
-    /// ForPrefix <- KEYWORD_for LPAREN Expr RPAREN PtrIndexPayload
-    ///
-    /// ForExpr <- ForPrefix Expr (KEYWORD_else Expr)?
-    fn parseForExpr(p: *Parser) !Node.Index {
-        const for_token = p.eatToken(.keyword_for) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const array_expr = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        const found_payload = try p.parsePtrIndexPayload();
-        if (found_payload == 0) try p.warn(.expected_loop_payload);
-
-        const then_expr = try p.expectExpr();
-        _ = p.eatToken(.keyword_else) orelse {
-            return p.addNode(.{
-                .tag = .for_simple,
-                .main_token = for_token,
-                .data = .{
-                    .lhs = array_expr,
-                    .rhs = then_expr,
-                },
-            });
-        };
-        const else_expr = try p.expectExpr();
-        return p.addNode(.{
-            .tag = .@"for",
-            .main_token = for_token,
-            .data = .{
-                .lhs = array_expr,
-                .rhs = try p.addExtra(Node.If{
-                    .then_expr = then_expr,
-                    .else_expr = else_expr,
-                }),
-            },
-        });
-    }
-
-    /// WhilePrefix <- KEYWORD_while LPAREN Expr RPAREN PtrPayload? WhileContinueExpr?
-    ///
-    /// WhileExpr <- WhilePrefix Expr (KEYWORD_else Payload? Expr)?
-    fn parseWhileExpr(p: *Parser) !Node.Index {
-        const while_token = p.eatToken(.keyword_while) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const condition = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        _ = try p.parsePtrPayload();
-        const cont_expr = try p.parseWhileContinueExpr();
-
-        const then_expr = try p.expectExpr();
-        _ = p.eatToken(.keyword_else) orelse {
-            if (cont_expr == 0) {
-                return p.addNode(.{
-                    .tag = .while_simple,
-                    .main_token = while_token,
-                    .data = .{
-                        .lhs = condition,
-                        .rhs = then_expr,
-                    },
-                });
-            } else {
-                return p.addNode(.{
-                    .tag = .while_cont,
-                    .main_token = while_token,
-                    .data = .{
-                        .lhs = condition,
-                        .rhs = try p.addExtra(Node.WhileCont{
-                            .cont_expr = cont_expr,
-                            .then_expr = then_expr,
-                        }),
-                    },
-                });
-            }
-        };
-        _ = try p.parsePayload();
-        const else_expr = try p.expectExpr();
-        return p.addNode(.{
-            .tag = .@"while",
-            .main_token = while_token,
-            .data = .{
-                .lhs = condition,
-                .rhs = try p.addExtra(Node.While{
-                    .cont_expr = cont_expr,
-                    .then_expr = then_expr,
-                    .else_expr = else_expr,
-                }),
-            },
-        });
-    }
-
-    /// CurlySuffixExpr <- TypeExpr InitList?
-    ///
-    /// InitList
-    ///     <- LBRACE FieldInit (COMMA FieldInit)* COMMA? RBRACE
-    ///      / LBRACE Expr (COMMA Expr)* COMMA? RBRACE
-    ///      / LBRACE RBRACE
-    fn parseCurlySuffixExpr(p: *Parser) !Node.Index {
-        const lhs = try p.parseTypeExpr();
-        if (lhs == 0) return null_node;
-        const lbrace = p.eatToken(.l_brace) orelse return lhs;
-
-        // If there are 0 or 1 items, we can use ArrayInitOne/StructInitOne;
-        // otherwise we use the full ArrayInit/StructInit.
-
-        const scratch_top = p.scratch.items.len;
-        defer p.scratch.shrinkRetainingCapacity(scratch_top);
-        const field_init = try p.parseFieldInit();
-        if (field_init != 0) {
-            try p.scratch.append(p.gpa, field_init);
-            while (true) {
-                switch (p.token_tags[p.tok_i]) {
-                    .comma => p.tok_i += 1,
-                    .r_brace => {
-                        p.tok_i += 1;
-                        break;
-                    },
-                    .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
-                    // Likely just a missing comma; give error but continue parsing.
-                    else => try p.warn(.expected_comma_after_initializer),
-                }
-                if (p.eatToken(.r_brace)) |_| break;
-                const next = try p.expectFieldInit();
-                try p.scratch.append(p.gpa, next);
-            }
-            const comma = (p.token_tags[p.tok_i - 2] == .comma);
-            const inits = p.scratch.items[scratch_top..];
-            switch (inits.len) {
-                0 => unreachable,
-                1 => return p.addNode(.{
-                    .tag = if (comma) .struct_init_one_comma else .struct_init_one,
-                    .main_token = lbrace,
-                    .data = .{
-                        .lhs = lhs,
-                        .rhs = inits[0],
-                    },
-                }),
-                else => return p.addNode(.{
-                    .tag = if (comma) .struct_init_comma else .struct_init,
-                    .main_token = lbrace,
-                    .data = .{
-                        .lhs = lhs,
-                        .rhs = try p.addExtra(try p.listToSpan(inits)),
-                    },
-                }),
-            }
-        }
-
-        while (true) {
-            if (p.eatToken(.r_brace)) |_| break;
-            const elem_init = try p.expectExpr();
-            try p.scratch.append(p.gpa, elem_init);
-            switch (p.token_tags[p.tok_i]) {
-                .comma => p.tok_i += 1,
-                .r_brace => {
-                    p.tok_i += 1;
-                    break;
-                },
-                .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
-                // Likely just a missing comma; give error but continue parsing.
-                else => try p.warn(.expected_comma_after_initializer),
-            }
-        }
-        const comma = (p.token_tags[p.tok_i - 2] == .comma);
-        const inits = p.scratch.items[scratch_top..];
-        switch (inits.len) {
-            0 => return p.addNode(.{
-                .tag = .struct_init_one,
-                .main_token = lbrace,
-                .data = .{
-                    .lhs = lhs,
-                    .rhs = 0,
-                },
-            }),
-            1 => return p.addNode(.{
-                .tag = if (comma) .array_init_one_comma else .array_init_one,
-                .main_token = lbrace,
-                .data = .{
-                    .lhs = lhs,
-                    .rhs = inits[0],
-                },
-            }),
-            else => return p.addNode(.{
-                .tag = if (comma) .array_init_comma else .array_init,
-                .main_token = lbrace,
-                .data = .{
-                    .lhs = lhs,
-                    .rhs = try p.addExtra(try p.listToSpan(inits)),
-                },
-            }),
-        }
-    }
-
-    /// ErrorUnionExpr <- SuffixExpr (EXCLAMATIONMARK TypeExpr)?
-    fn parseErrorUnionExpr(p: *Parser) !Node.Index {
-        const suffix_expr = try p.parseSuffixExpr();
-        if (suffix_expr == 0) return null_node;
-        const bang = p.eatToken(.bang) orelse return suffix_expr;
-        return p.addNode(.{
-            .tag = .error_union,
-            .main_token = bang,
-            .data = .{
-                .lhs = suffix_expr,
-                .rhs = try p.expectTypeExpr(),
-            },
-        });
-    }
-
-    /// SuffixExpr
-    ///     <- KEYWORD_async PrimaryTypeExpr SuffixOp* FnCallArguments
-    ///      / PrimaryTypeExpr (SuffixOp / FnCallArguments)*
-    ///
-    /// FnCallArguments <- LPAREN ExprList RPAREN
-    ///
-    /// ExprList <- (Expr COMMA)* Expr?
-    fn parseSuffixExpr(p: *Parser) !Node.Index {
-        if (p.eatToken(.keyword_async)) |_| {
-            var res = try p.expectPrimaryTypeExpr();
-            while (true) {
-                const node = try p.parseSuffixOp(res);
-                if (node == 0) break;
-                res = node;
-            }
-            const lparen = p.eatToken(.l_paren) orelse {
-                try p.warn(.expected_param_list);
-                return res;
-            };
-            const scratch_top = p.scratch.items.len;
-            defer p.scratch.shrinkRetainingCapacity(scratch_top);
-            while (true) {
-                if (p.eatToken(.r_paren)) |_| break;
-                const param = try p.expectExpr();
-                try p.scratch.append(p.gpa, param);
-                switch (p.token_tags[p.tok_i]) {
-                    .comma => p.tok_i += 1,
-                    .r_paren => {
-                        p.tok_i += 1;
-                        break;
-                    },
-                    .colon, .r_brace, .r_bracket => return p.failExpected(.r_paren),
-                    // Likely just a missing comma; give error but continue parsing.
-                    else => try p.warn(.expected_comma_after_arg),
-                }
-            }
-            const comma = (p.token_tags[p.tok_i - 2] == .comma);
-            const params = p.scratch.items[scratch_top..];
-            switch (params.len) {
-                0 => return p.addNode(.{
-                    .tag = if (comma) .async_call_one_comma else .async_call_one,
-                    .main_token = lparen,
-                    .data = .{
-                        .lhs = res,
-                        .rhs = 0,
-                    },
-                }),
-                1 => return p.addNode(.{
-                    .tag = if (comma) .async_call_one_comma else .async_call_one,
-                    .main_token = lparen,
-                    .data = .{
-                        .lhs = res,
-                        .rhs = params[0],
-                    },
-                }),
-                else => return p.addNode(.{
-                    .tag = if (comma) .async_call_comma else .async_call,
-                    .main_token = lparen,
-                    .data = .{
-                        .lhs = res,
-                        .rhs = try p.addExtra(try p.listToSpan(params)),
-                    },
-                }),
-            }
-        }
-
-        var res = try p.parsePrimaryTypeExpr();
-        if (res == 0) return res;
-        while (true) {
-            const suffix_op = try p.parseSuffixOp(res);
-            if (suffix_op != 0) {
-                res = suffix_op;
-                continue;
-            }
-            const lparen = p.eatToken(.l_paren) orelse return res;
-            const scratch_top = p.scratch.items.len;
-            defer p.scratch.shrinkRetainingCapacity(scratch_top);
-            while (true) {
-                if (p.eatToken(.r_paren)) |_| break;
-                const param = try p.expectExpr();
-                try p.scratch.append(p.gpa, param);
-                switch (p.token_tags[p.tok_i]) {
-                    .comma => p.tok_i += 1,
-                    .r_paren => {
-                        p.tok_i += 1;
-                        break;
-                    },
-                    .colon, .r_brace, .r_bracket => return p.failExpected(.r_paren),
-                    // Likely just a missing comma; give error but continue parsing.
-                    else => try p.warn(.expected_comma_after_arg),
-                }
-            }
-            const comma = (p.token_tags[p.tok_i - 2] == .comma);
-            const params = p.scratch.items[scratch_top..];
-            res = switch (params.len) {
-                0 => try p.addNode(.{
-                    .tag = if (comma) .call_one_comma else .call_one,
-                    .main_token = lparen,
-                    .data = .{
-                        .lhs = res,
-                        .rhs = 0,
-                    },
-                }),
-                1 => try p.addNode(.{
-                    .tag = if (comma) .call_one_comma else .call_one,
-                    .main_token = lparen,
-                    .data = .{
-                        .lhs = res,
-                        .rhs = params[0],
-                    },
-                }),
-                else => try p.addNode(.{
-                    .tag = if (comma) .call_comma else .call,
-                    .main_token = lparen,
-                    .data = .{
-                        .lhs = res,
-                        .rhs = try p.addExtra(try p.listToSpan(params)),
-                    },
-                }),
-            };
-        }
-    }
-
-    /// PrimaryTypeExpr
-    ///     <- BUILTINIDENTIFIER FnCallArguments
-    ///      / CHAR_LITERAL
-    ///      / ContainerDecl
-    ///      / DOT IDENTIFIER
-    ///      / DOT InitList
-    ///      / ErrorSetDecl
-    ///      / FLOAT
-    ///      / FnProto
-    ///      / GroupedExpr
-    ///      / LabeledTypeExpr
-    ///      / IDENTIFIER
-    ///      / IfTypeExpr
-    ///      / INTEGER
-    ///      / KEYWORD_comptime TypeExpr
-    ///      / KEYWORD_error DOT IDENTIFIER
-    ///      / KEYWORD_anyframe
-    ///      / KEYWORD_unreachable
-    ///      / STRINGLITERAL
-    ///      / SwitchExpr
-    ///
-    /// ContainerDecl <- (KEYWORD_extern / KEYWORD_packed)? ContainerDeclAuto
-    ///
-    /// ContainerDeclAuto <- ContainerDeclType LBRACE container_doc_comment? ContainerMembers RBRACE
-    ///
-    /// InitList
-    ///     <- LBRACE FieldInit (COMMA FieldInit)* COMMA? RBRACE
-    ///      / LBRACE Expr (COMMA Expr)* COMMA? RBRACE
-    ///      / LBRACE RBRACE
-    ///
-    /// ErrorSetDecl <- KEYWORD_error LBRACE IdentifierList RBRACE
-    ///
-    /// GroupedExpr <- LPAREN Expr RPAREN
-    ///
-    /// IfTypeExpr <- IfPrefix TypeExpr (KEYWORD_else Payload? TypeExpr)?
-    ///
-    /// LabeledTypeExpr
-    ///     <- BlockLabel Block
-    ///      / BlockLabel? LoopTypeExpr
-    ///
-    /// LoopTypeExpr <- KEYWORD_inline? (ForTypeExpr / WhileTypeExpr)
-    fn parsePrimaryTypeExpr(p: *Parser) !Node.Index {
-        switch (p.token_tags[p.tok_i]) {
-            .char_literal => return p.addNode(.{
-                .tag = .char_literal,
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = undefined,
-                    .rhs = undefined,
-                },
-            }),
-            .number_literal => return p.addNode(.{
-                .tag = .number_literal,
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = undefined,
-                    .rhs = undefined,
-                },
-            }),
-            .keyword_unreachable => return p.addNode(.{
-                .tag = .unreachable_literal,
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = undefined,
-                    .rhs = undefined,
-                },
-            }),
-            .keyword_anyframe => return p.addNode(.{
-                .tag = .anyframe_literal,
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = undefined,
-                    .rhs = undefined,
-                },
-            }),
-            .string_literal => {
-                const main_token = p.nextToken();
-                return p.addNode(.{
-                    .tag = .string_literal,
-                    .main_token = main_token,
-                    .data = .{
-                        .lhs = undefined,
-                        .rhs = undefined,
-                    },
-                });
-            },
-
-            .builtin => return p.parseBuiltinCall(),
-            .keyword_fn => return p.parseFnProto(),
-            .keyword_if => return p.parseIf(expectTypeExpr),
-            .keyword_switch => return p.expectSwitchExpr(),
-
-            .keyword_extern,
-            .keyword_packed,
-            => {
-                p.tok_i += 1;
-                return p.parseContainerDeclAuto();
-            },
-
-            .keyword_struct,
-            .keyword_opaque,
-            .keyword_enum,
-            .keyword_union,
-            => return p.parseContainerDeclAuto(),
-
-            .keyword_comptime => return p.addNode(.{
-                .tag = .@"comptime",
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = try p.expectTypeExpr(),
-                    .rhs = undefined,
-                },
-            }),
-            .multiline_string_literal_line => {
-                const first_line = p.nextToken();
-                while (p.token_tags[p.tok_i] == .multiline_string_literal_line) {
-                    p.tok_i += 1;
-                }
-                return p.addNode(.{
-                    .tag = .multiline_string_literal,
-                    .main_token = first_line,
-                    .data = .{
-                        .lhs = first_line,
-                        .rhs = p.tok_i - 1,
-                    },
-                });
-            },
-            .identifier => switch (p.token_tags[p.tok_i + 1]) {
-                .colon => switch (p.token_tags[p.tok_i + 2]) {
-                    .keyword_inline => {
-                        p.tok_i += 3;
-                        switch (p.token_tags[p.tok_i]) {
-                            .keyword_for => return p.parseForTypeExpr(),
-                            .keyword_while => return p.parseWhileTypeExpr(),
-                            else => return p.fail(.expected_inlinable),
-                        }
-                    },
-                    .keyword_for => {
-                        p.tok_i += 2;
-                        return p.parseForTypeExpr();
-                    },
-                    .keyword_while => {
-                        p.tok_i += 2;
-                        return p.parseWhileTypeExpr();
-                    },
-                    .l_brace => {
-                        p.tok_i += 2;
-                        return p.parseBlock();
-                    },
-                    else => return p.addNode(.{
-                        .tag = .identifier,
-                        .main_token = p.nextToken(),
-                        .data = .{
-                            .lhs = undefined,
-                            .rhs = undefined,
-                        },
-                    }),
-                },
-                else => return p.addNode(.{
-                    .tag = .identifier,
-                    .main_token = p.nextToken(),
-                    .data = .{
-                        .lhs = undefined,
-                        .rhs = undefined,
-                    },
-                }),
-            },
-            .keyword_inline => {
-                p.tok_i += 1;
-                switch (p.token_tags[p.tok_i]) {
-                    .keyword_for => return p.parseForTypeExpr(),
-                    .keyword_while => return p.parseWhileTypeExpr(),
-                    else => return p.fail(.expected_inlinable),
-                }
-            },
-            .keyword_for => return p.parseForTypeExpr(),
-            .keyword_while => return p.parseWhileTypeExpr(),
-            .period => switch (p.token_tags[p.tok_i + 1]) {
-                .identifier => return p.addNode(.{
-                    .tag = .enum_literal,
-                    .data = .{
-                        .lhs = p.nextToken(), // dot
-                        .rhs = undefined,
-                    },
-                    .main_token = p.nextToken(), // identifier
-                }),
-                .l_brace => {
-                    const lbrace = p.tok_i + 1;
-                    p.tok_i = lbrace + 1;
-
-                    // If there are 0, 1, or 2 items, we can use ArrayInitDotTwo/StructInitDotTwo;
-                    // otherwise we use the full ArrayInitDot/StructInitDot.
-
-                    const scratch_top = p.scratch.items.len;
-                    defer p.scratch.shrinkRetainingCapacity(scratch_top);
-                    const field_init = try p.parseFieldInit();
-                    if (field_init != 0) {
-                        try p.scratch.append(p.gpa, field_init);
-                        while (true) {
-                            switch (p.token_tags[p.tok_i]) {
-                                .comma => p.tok_i += 1,
-                                .r_brace => {
-                                    p.tok_i += 1;
-                                    break;
-                                },
-                                .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
-                                // Likely just a missing comma; give error but continue parsing.
-                                else => try p.warn(.expected_comma_after_initializer),
-                            }
-                            if (p.eatToken(.r_brace)) |_| break;
-                            const next = try p.expectFieldInit();
-                            try p.scratch.append(p.gpa, next);
-                        }
-                        const comma = (p.token_tags[p.tok_i - 2] == .comma);
-                        const inits = p.scratch.items[scratch_top..];
-                        switch (inits.len) {
-                            0 => unreachable,
-                            1 => return p.addNode(.{
-                                .tag = if (comma) .struct_init_dot_two_comma else .struct_init_dot_two,
-                                .main_token = lbrace,
-                                .data = .{
-                                    .lhs = inits[0],
-                                    .rhs = 0,
-                                },
-                            }),
-                            2 => return p.addNode(.{
-                                .tag = if (comma) .struct_init_dot_two_comma else .struct_init_dot_two,
-                                .main_token = lbrace,
-                                .data = .{
-                                    .lhs = inits[0],
-                                    .rhs = inits[1],
-                                },
-                            }),
-                            else => {
-                                const span = try p.listToSpan(inits);
-                                return p.addNode(.{
-                                    .tag = if (comma) .struct_init_dot_comma else .struct_init_dot,
-                                    .main_token = lbrace,
-                                    .data = .{
-                                        .lhs = span.start,
-                                        .rhs = span.end,
-                                    },
-                                });
-                            },
-                        }
-                    }
-
-                    while (true) {
-                        if (p.eatToken(.r_brace)) |_| break;
-                        const elem_init = try p.expectExpr();
-                        try p.scratch.append(p.gpa, elem_init);
-                        switch (p.token_tags[p.tok_i]) {
-                            .comma => p.tok_i += 1,
-                            .r_brace => {
-                                p.tok_i += 1;
-                                break;
-                            },
-                            .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
-                            // Likely just a missing comma; give error but continue parsing.
-                            else => try p.warn(.expected_comma_after_initializer),
-                        }
-                    }
-                    const comma = (p.token_tags[p.tok_i - 2] == .comma);
-                    const inits = p.scratch.items[scratch_top..];
-                    switch (inits.len) {
-                        0 => return p.addNode(.{
-                            .tag = .struct_init_dot_two,
-                            .main_token = lbrace,
-                            .data = .{
-                                .lhs = 0,
-                                .rhs = 0,
-                            },
-                        }),
-                        1 => return p.addNode(.{
-                            .tag = if (comma) .array_init_dot_two_comma else .array_init_dot_two,
-                            .main_token = lbrace,
-                            .data = .{
-                                .lhs = inits[0],
-                                .rhs = 0,
-                            },
-                        }),
-                        2 => return p.addNode(.{
-                            .tag = if (comma) .array_init_dot_two_comma else .array_init_dot_two,
-                            .main_token = lbrace,
-                            .data = .{
-                                .lhs = inits[0],
-                                .rhs = inits[1],
-                            },
-                        }),
-                        else => {
-                            const span = try p.listToSpan(inits);
-                            return p.addNode(.{
-                                .tag = if (comma) .array_init_dot_comma else .array_init_dot,
-                                .main_token = lbrace,
-                                .data = .{
-                                    .lhs = span.start,
-                                    .rhs = span.end,
-                                },
-                            });
-                        },
-                    }
-                },
-                else => return null_node,
-            },
-            .keyword_error => switch (p.token_tags[p.tok_i + 1]) {
-                .l_brace => {
-                    const error_token = p.tok_i;
-                    p.tok_i += 2;
-                    while (true) {
-                        if (p.eatToken(.r_brace)) |_| break;
-                        _ = try p.eatDocComments();
-                        _ = try p.expectToken(.identifier);
-                        switch (p.token_tags[p.tok_i]) {
-                            .comma => p.tok_i += 1,
-                            .r_brace => {
-                                p.tok_i += 1;
-                                break;
-                            },
-                            .colon, .r_paren, .r_bracket => return p.failExpected(.r_brace),
-                            // Likely just a missing comma; give error but continue parsing.
-                            else => try p.warn(.expected_comma_after_field),
-                        }
-                    }
-                    return p.addNode(.{
-                        .tag = .error_set_decl,
-                        .main_token = error_token,
-                        .data = .{
-                            .lhs = undefined,
-                            .rhs = p.tok_i - 1, // rbrace
-                        },
-                    });
-                },
-                else => {
-                    const main_token = p.nextToken();
-                    const period = p.eatToken(.period);
-                    if (period == null) try p.warnExpected(.period);
-                    const identifier = p.eatToken(.identifier);
-                    if (identifier == null) try p.warnExpected(.identifier);
-                    return p.addNode(.{
-                        .tag = .error_value,
-                        .main_token = main_token,
-                        .data = .{
-                            .lhs = period orelse 0,
-                            .rhs = identifier orelse 0,
-                        },
-                    });
-                },
-            },
-            .l_paren => return p.addNode(.{
-                .tag = .grouped_expression,
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = try p.expectExpr(),
-                    .rhs = try p.expectToken(.r_paren),
-                },
-            }),
-            else => return null_node,
-        }
-    }
-
-    fn expectPrimaryTypeExpr(p: *Parser) !Node.Index {
-        const node = try p.parsePrimaryTypeExpr();
-        if (node == 0) {
-            return p.fail(.expected_primary_type_expr);
-        }
-        return node;
-    }
-
-    /// ForPrefix <- KEYWORD_for LPAREN Expr RPAREN PtrIndexPayload
-    ///
-    /// ForTypeExpr <- ForPrefix TypeExpr (KEYWORD_else TypeExpr)?
-    fn parseForTypeExpr(p: *Parser) !Node.Index {
-        const for_token = p.eatToken(.keyword_for) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const array_expr = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        const found_payload = try p.parsePtrIndexPayload();
-        if (found_payload == 0) try p.warn(.expected_loop_payload);
-
-        const then_expr = try p.expectTypeExpr();
-        _ = p.eatToken(.keyword_else) orelse {
-            return p.addNode(.{
-                .tag = .for_simple,
-                .main_token = for_token,
-                .data = .{
-                    .lhs = array_expr,
-                    .rhs = then_expr,
-                },
-            });
-        };
-        const else_expr = try p.expectTypeExpr();
-        return p.addNode(.{
-            .tag = .@"for",
-            .main_token = for_token,
-            .data = .{
-                .lhs = array_expr,
-                .rhs = try p.addExtra(Node.If{
-                    .then_expr = then_expr,
-                    .else_expr = else_expr,
-                }),
-            },
-        });
-    }
-
-    /// WhilePrefix <- KEYWORD_while LPAREN Expr RPAREN PtrPayload? WhileContinueExpr?
-    ///
-    /// WhileTypeExpr <- WhilePrefix TypeExpr (KEYWORD_else Payload? TypeExpr)?
-    fn parseWhileTypeExpr(p: *Parser) !Node.Index {
-        const while_token = p.eatToken(.keyword_while) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const condition = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        _ = try p.parsePtrPayload();
-        const cont_expr = try p.parseWhileContinueExpr();
-
-        const then_expr = try p.expectTypeExpr();
-        _ = p.eatToken(.keyword_else) orelse {
-            if (cont_expr == 0) {
-                return p.addNode(.{
-                    .tag = .while_simple,
-                    .main_token = while_token,
-                    .data = .{
-                        .lhs = condition,
-                        .rhs = then_expr,
-                    },
-                });
-            } else {
-                return p.addNode(.{
-                    .tag = .while_cont,
-                    .main_token = while_token,
-                    .data = .{
-                        .lhs = condition,
-                        .rhs = try p.addExtra(Node.WhileCont{
-                            .cont_expr = cont_expr,
-                            .then_expr = then_expr,
-                        }),
-                    },
-                });
-            }
-        };
-        _ = try p.parsePayload();
-        const else_expr = try p.expectTypeExpr();
-        return p.addNode(.{
-            .tag = .@"while",
-            .main_token = while_token,
-            .data = .{
-                .lhs = condition,
-                .rhs = try p.addExtra(Node.While{
-                    .cont_expr = cont_expr,
-                    .then_expr = then_expr,
-                    .else_expr = else_expr,
-                }),
-            },
-        });
-    }
-
-    /// SwitchExpr <- KEYWORD_switch LPAREN Expr RPAREN LBRACE SwitchProngList RBRACE
-    fn expectSwitchExpr(p: *Parser) !Node.Index {
-        const switch_token = p.assertToken(.keyword_switch);
-        _ = try p.expectToken(.l_paren);
-        const expr_node = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        _ = try p.expectToken(.l_brace);
-        const cases = try p.parseSwitchProngList();
-        const trailing_comma = p.token_tags[p.tok_i - 1] == .comma;
-        _ = try p.expectToken(.r_brace);
-
-        return p.addNode(.{
-            .tag = if (trailing_comma) .switch_comma else .@"switch",
-            .main_token = switch_token,
-            .data = .{
-                .lhs = expr_node,
-                .rhs = try p.addExtra(Node.SubRange{
-                    .start = cases.start,
-                    .end = cases.end,
-                }),
-            },
-        });
-    }
-
-    /// AsmExpr <- KEYWORD_asm KEYWORD_volatile? LPAREN Expr AsmOutput? RPAREN
-    ///
-    /// AsmOutput <- COLON AsmOutputList AsmInput?
-    ///
-    /// AsmInput <- COLON AsmInputList AsmClobbers?
-    ///
-    /// AsmClobbers <- COLON StringList
-    ///
-    /// StringList <- (STRINGLITERAL COMMA)* STRINGLITERAL?
-    ///
-    /// AsmOutputList <- (AsmOutputItem COMMA)* AsmOutputItem?
-    ///
-    /// AsmInputList <- (AsmInputItem COMMA)* AsmInputItem?
-    fn expectAsmExpr(p: *Parser) !Node.Index {
-        const asm_token = p.assertToken(.keyword_asm);
-        _ = p.eatToken(.keyword_volatile);
-        _ = try p.expectToken(.l_paren);
-        const template = try p.expectExpr();
-
-        if (p.eatToken(.r_paren)) |rparen| {
-            return p.addNode(.{
-                .tag = .asm_simple,
-                .main_token = asm_token,
-                .data = .{
-                    .lhs = template,
-                    .rhs = rparen,
-                },
-            });
-        }
-
-        _ = try p.expectToken(.colon);
-
-        const scratch_top = p.scratch.items.len;
-        defer p.scratch.shrinkRetainingCapacity(scratch_top);
-
-        while (true) {
-            const output_item = try p.parseAsmOutputItem();
-            if (output_item == 0) break;
-            try p.scratch.append(p.gpa, output_item);
-            switch (p.token_tags[p.tok_i]) {
-                .comma => p.tok_i += 1,
-                // All possible delimiters.
-                .colon, .r_paren, .r_brace, .r_bracket => break,
-                // Likely just a missing comma; give error but continue parsing.
-                else => try p.warnExpected(.comma),
-            }
-        }
-        if (p.eatToken(.colon)) |_| {
-            while (true) {
-                const input_item = try p.parseAsmInputItem();
-                if (input_item == 0) break;
-                try p.scratch.append(p.gpa, input_item);
-                switch (p.token_tags[p.tok_i]) {
-                    .comma => p.tok_i += 1,
-                    // All possible delimiters.
-                    .colon, .r_paren, .r_brace, .r_bracket => break,
-                    // Likely just a missing comma; give error but continue parsing.
-                    else => try p.warnExpected(.comma),
-                }
-            }
-            if (p.eatToken(.colon)) |_| {
-                while (p.eatToken(.string_literal)) |_| {
-                    switch (p.token_tags[p.tok_i]) {
-                        .comma => p.tok_i += 1,
-                        .colon, .r_paren, .r_brace, .r_bracket => break,
-                        // Likely just a missing comma; give error but continue parsing.
-                        else => try p.warnExpected(.comma),
-                    }
-                }
-            }
-        }
-        const rparen = try p.expectToken(.r_paren);
-        const span = try p.listToSpan(p.scratch.items[scratch_top..]);
-        return p.addNode(.{
-            .tag = .@"asm",
-            .main_token = asm_token,
-            .data = .{
-                .lhs = template,
-                .rhs = try p.addExtra(Node.Asm{
-                    .items_start = span.start,
-                    .items_end = span.end,
-                    .rparen = rparen,
-                }),
-            },
-        });
-    }
-
-    /// AsmOutputItem <- LBRACKET IDENTIFIER RBRACKET STRINGLITERAL LPAREN (MINUSRARROW TypeExpr / IDENTIFIER) RPAREN
-    fn parseAsmOutputItem(p: *Parser) !Node.Index {
-        _ = p.eatToken(.l_bracket) orelse return null_node;
-        const identifier = try p.expectToken(.identifier);
-        _ = try p.expectToken(.r_bracket);
-        _ = try p.expectToken(.string_literal);
-        _ = try p.expectToken(.l_paren);
-        const type_expr: Node.Index = blk: {
-            if (p.eatToken(.arrow)) |_| {
-                break :blk try p.expectTypeExpr();
-            } else {
-                _ = try p.expectToken(.identifier);
-                break :blk null_node;
-            }
-        };
-        const rparen = try p.expectToken(.r_paren);
-        return p.addNode(.{
-            .tag = .asm_output,
-            .main_token = identifier,
-            .data = .{
-                .lhs = type_expr,
-                .rhs = rparen,
-            },
-        });
-    }
-
-    /// AsmInputItem <- LBRACKET IDENTIFIER RBRACKET STRINGLITERAL LPAREN Expr RPAREN
-    fn parseAsmInputItem(p: *Parser) !Node.Index {
-        _ = p.eatToken(.l_bracket) orelse return null_node;
-        const identifier = try p.expectToken(.identifier);
-        _ = try p.expectToken(.r_bracket);
-        _ = try p.expectToken(.string_literal);
-        _ = try p.expectToken(.l_paren);
-        const expr = try p.expectExpr();
-        const rparen = try p.expectToken(.r_paren);
-        return p.addNode(.{
-            .tag = .asm_input,
-            .main_token = identifier,
-            .data = .{
-                .lhs = expr,
-                .rhs = rparen,
-            },
-        });
-    }
-
-    /// BreakLabel <- COLON IDENTIFIER
-    fn parseBreakLabel(p: *Parser) !TokenIndex {
-        _ = p.eatToken(.colon) orelse return @as(TokenIndex, 0);
-        return p.expectToken(.identifier);
-    }
-
-    /// BlockLabel <- IDENTIFIER COLON
-    fn parseBlockLabel(p: *Parser) TokenIndex {
-        if (p.token_tags[p.tok_i] == .identifier and
-            p.token_tags[p.tok_i + 1] == .colon)
-        {
-            const identifier = p.tok_i;
-            p.tok_i += 2;
-            return identifier;
-        }
-        return null_node;
-    }
-
-    /// FieldInit <- DOT IDENTIFIER EQUAL Expr
-    fn parseFieldInit(p: *Parser) !Node.Index {
-        if (p.token_tags[p.tok_i + 0] == .period and
-            p.token_tags[p.tok_i + 1] == .identifier and
-            p.token_tags[p.tok_i + 2] == .equal)
-        {
-            p.tok_i += 3;
-            return p.expectExpr();
-        } else {
-            return null_node;
-        }
-    }
-
-    fn expectFieldInit(p: *Parser) !Node.Index {
-        if (p.token_tags[p.tok_i] != .period or
-            p.token_tags[p.tok_i + 1] != .identifier or
-            p.token_tags[p.tok_i + 2] != .equal)
-            return p.fail(.expected_initializer);
-
-        p.tok_i += 3;
-        return p.expectExpr();
-    }
-
-    /// WhileContinueExpr <- COLON LPAREN AssignExpr RPAREN
-    fn parseWhileContinueExpr(p: *Parser) !Node.Index {
-        _ = p.eatToken(.colon) orelse {
-            if (p.token_tags[p.tok_i] == .l_paren and
-                p.tokensOnSameLine(p.tok_i - 1, p.tok_i))
-                return p.fail(.expected_continue_expr);
-            return null_node;
-        };
-        _ = try p.expectToken(.l_paren);
-        const node = try p.parseAssignExpr();
-        if (node == 0) return p.fail(.expected_expr_or_assignment);
-        _ = try p.expectToken(.r_paren);
-        return node;
-    }
-
-    /// LinkSection <- KEYWORD_linksection LPAREN Expr RPAREN
-    fn parseLinkSection(p: *Parser) !Node.Index {
-        _ = p.eatToken(.keyword_linksection) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const expr_node = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        return expr_node;
-    }
-
-    /// CallConv <- KEYWORD_callconv LPAREN Expr RPAREN
-    fn parseCallconv(p: *Parser) !Node.Index {
-        _ = p.eatToken(.keyword_callconv) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const expr_node = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        return expr_node;
-    }
-
-    /// AddrSpace <- KEYWORD_addrspace LPAREN Expr RPAREN
-    fn parseAddrSpace(p: *Parser) !Node.Index {
-        _ = p.eatToken(.keyword_addrspace) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const expr_node = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        return expr_node;
-    }
-
-    /// This function can return null nodes and then still return nodes afterwards,
-    /// such as in the case of anytype and `...`. Caller must look for rparen to find
-    /// out when there are no more param decls left.
-    ///
-    /// ParamDecl
-    ///     <- doc_comment? (KEYWORD_noalias / KEYWORD_comptime)? (IDENTIFIER COLON)? ParamType
-    ///      / DOT3
-    ///
-    /// ParamType
-    ///     <- KEYWORD_anytype
-    ///      / TypeExpr
-    fn expectParamDecl(p: *Parser) !Node.Index {
-        _ = try p.eatDocComments();
-        switch (p.token_tags[p.tok_i]) {
-            .keyword_noalias, .keyword_comptime => p.tok_i += 1,
-            .ellipsis3 => {
-                p.tok_i += 1;
-                return null_node;
-            },
-            else => {},
-        }
-        if (p.token_tags[p.tok_i] == .identifier and
-            p.token_tags[p.tok_i + 1] == .colon)
-        {
-            p.tok_i += 2;
-        }
-        switch (p.token_tags[p.tok_i]) {
-            .keyword_anytype => {
-                p.tok_i += 1;
-                return null_node;
-            },
-            else => return p.expectTypeExpr(),
-        }
-    }
-
-    /// Payload <- PIPE IDENTIFIER PIPE
-    fn parsePayload(p: *Parser) !TokenIndex {
-        _ = p.eatToken(.pipe) orelse return @as(TokenIndex, 0);
-        const identifier = try p.expectToken(.identifier);
-        _ = try p.expectToken(.pipe);
-        return identifier;
-    }
-
-    /// PtrPayload <- PIPE ASTERISK? IDENTIFIER PIPE
-    fn parsePtrPayload(p: *Parser) !TokenIndex {
-        _ = p.eatToken(.pipe) orelse return @as(TokenIndex, 0);
-        _ = p.eatToken(.asterisk);
-        const identifier = try p.expectToken(.identifier);
-        _ = try p.expectToken(.pipe);
-        return identifier;
-    }
-
-    /// Returns the first identifier token, if any.
-    ///
-    /// PtrIndexPayload <- PIPE ASTERISK? IDENTIFIER (COMMA IDENTIFIER)? PIPE
-    fn parsePtrIndexPayload(p: *Parser) !TokenIndex {
-        _ = p.eatToken(.pipe) orelse return @as(TokenIndex, 0);
-        _ = p.eatToken(.asterisk);
-        const identifier = try p.expectToken(.identifier);
-        if (p.eatToken(.comma) != null) {
-            _ = try p.expectToken(.identifier);
-        }
-        _ = try p.expectToken(.pipe);
-        return identifier;
-    }
-
-    /// SwitchProng <- KEYWORD_inline? SwitchCase EQUALRARROW PtrIndexPayload? AssignExpr
-    ///
-    /// SwitchCase
-    ///     <- SwitchItem (COMMA SwitchItem)* COMMA?
-    ///      / KEYWORD_else
-    fn parseSwitchProng(p: *Parser) !Node.Index {
-        const scratch_top = p.scratch.items.len;
-        defer p.scratch.shrinkRetainingCapacity(scratch_top);
-
-        const is_inline = p.eatToken(.keyword_inline) != null;
-
-        if (p.eatToken(.keyword_else) == null) {
-            while (true) {
-                const item = try p.parseSwitchItem();
-                if (item == 0) break;
-                try p.scratch.append(p.gpa, item);
-                if (p.eatToken(.comma) == null) break;
-            }
-            if (scratch_top == p.scratch.items.len) {
-                if (is_inline) p.tok_i -= 1;
-                return null_node;
-            }
-        }
-        const arrow_token = try p.expectToken(.equal_angle_bracket_right);
-        _ = try p.parsePtrIndexPayload();
-
-        const items = p.scratch.items[scratch_top..];
-        switch (items.len) {
-            0 => return p.addNode(.{
-                .tag = if (is_inline) .switch_case_inline_one else .switch_case_one,
-                .main_token = arrow_token,
-                .data = .{
-                    .lhs = 0,
-                    .rhs = try p.expectAssignExpr(),
-                },
-            }),
-            1 => return p.addNode(.{
-                .tag = if (is_inline) .switch_case_inline_one else .switch_case_one,
-                .main_token = arrow_token,
-                .data = .{
-                    .lhs = items[0],
-                    .rhs = try p.expectAssignExpr(),
-                },
-            }),
-            else => return p.addNode(.{
-                .tag = if (is_inline) .switch_case_inline else .switch_case,
-                .main_token = arrow_token,
-                .data = .{
-                    .lhs = try p.addExtra(try p.listToSpan(items)),
-                    .rhs = try p.expectAssignExpr(),
-                },
-            }),
-        }
-    }
-
-    /// SwitchItem <- Expr (DOT3 Expr)?
-    fn parseSwitchItem(p: *Parser) !Node.Index {
-        const expr = try p.parseExpr();
-        if (expr == 0) return null_node;
-
-        if (p.eatToken(.ellipsis3)) |token| {
-            return p.addNode(.{
-                .tag = .switch_range,
-                .main_token = token,
-                .data = .{
-                    .lhs = expr,
-                    .rhs = try p.expectExpr(),
-                },
-            });
-        }
-        return expr;
-    }
-
-    const PtrModifiers = struct {
-        align_node: Node.Index,
-        addrspace_node: Node.Index,
-        bit_range_start: Node.Index,
-        bit_range_end: Node.Index,
-    };
-
-    fn parsePtrModifiers(p: *Parser) !PtrModifiers {
-        var result: PtrModifiers = .{
-            .align_node = 0,
-            .addrspace_node = 0,
-            .bit_range_start = 0,
-            .bit_range_end = 0,
-        };
-        var saw_const = false;
-        var saw_volatile = false;
-        var saw_allowzero = false;
-        var saw_addrspace = false;
-        while (true) {
-            switch (p.token_tags[p.tok_i]) {
-                .keyword_align => {
-                    if (result.align_node != 0) {
-                        try p.warn(.extra_align_qualifier);
-                    }
-                    p.tok_i += 1;
-                    _ = try p.expectToken(.l_paren);
-                    result.align_node = try p.expectExpr();
-
-                    if (p.eatToken(.colon)) |_| {
-                        result.bit_range_start = try p.expectExpr();
-                        _ = try p.expectToken(.colon);
-                        result.bit_range_end = try p.expectExpr();
-                    }
-
-                    _ = try p.expectToken(.r_paren);
-                },
-                .keyword_const => {
-                    if (saw_const) {
-                        try p.warn(.extra_const_qualifier);
-                    }
-                    p.tok_i += 1;
-                    saw_const = true;
-                },
-                .keyword_volatile => {
-                    if (saw_volatile) {
-                        try p.warn(.extra_volatile_qualifier);
-                    }
-                    p.tok_i += 1;
-                    saw_volatile = true;
-                },
-                .keyword_allowzero => {
-                    if (saw_allowzero) {
-                        try p.warn(.extra_allowzero_qualifier);
-                    }
-                    p.tok_i += 1;
-                    saw_allowzero = true;
-                },
-                .keyword_addrspace => {
-                    if (saw_addrspace) {
-                        try p.warn(.extra_addrspace_qualifier);
-                    }
-                    result.addrspace_node = try p.parseAddrSpace();
-                },
-                else => return result,
-            }
-        }
-    }
-
-    /// SuffixOp
-    ///     <- LBRACKET Expr (DOT2 (Expr? (COLON Expr)?)?)? RBRACKET
-    ///      / DOT IDENTIFIER
-    ///      / DOTASTERISK
-    ///      / DOTQUESTIONMARK
-    fn parseSuffixOp(p: *Parser, lhs: Node.Index) !Node.Index {
-        switch (p.token_tags[p.tok_i]) {
-            .l_bracket => {
-                const lbracket = p.nextToken();
-                const index_expr = try p.expectExpr();
-
-                if (p.eatToken(.ellipsis2)) |_| {
-                    const end_expr = try p.parseExpr();
-                    if (p.eatToken(.colon)) |_| {
-                        const sentinel = try p.expectExpr();
-                        _ = try p.expectToken(.r_bracket);
-                        return p.addNode(.{
-                            .tag = .slice_sentinel,
-                            .main_token = lbracket,
-                            .data = .{
-                                .lhs = lhs,
-                                .rhs = try p.addExtra(Node.SliceSentinel{
-                                    .start = index_expr,
-                                    .end = end_expr,
-                                    .sentinel = sentinel,
-                                }),
-                            },
-                        });
-                    }
-                    _ = try p.expectToken(.r_bracket);
-                    if (end_expr == 0) {
-                        return p.addNode(.{
-                            .tag = .slice_open,
-                            .main_token = lbracket,
-                            .data = .{
-                                .lhs = lhs,
-                                .rhs = index_expr,
-                            },
-                        });
-                    }
-                    return p.addNode(.{
-                        .tag = .slice,
-                        .main_token = lbracket,
-                        .data = .{
-                            .lhs = lhs,
-                            .rhs = try p.addExtra(Node.Slice{
-                                .start = index_expr,
-                                .end = end_expr,
-                            }),
-                        },
-                    });
-                }
-                _ = try p.expectToken(.r_bracket);
-                return p.addNode(.{
-                    .tag = .array_access,
-                    .main_token = lbracket,
-                    .data = .{
-                        .lhs = lhs,
-                        .rhs = index_expr,
-                    },
-                });
-            },
-            .period_asterisk => return p.addNode(.{
-                .tag = .deref,
-                .main_token = p.nextToken(),
-                .data = .{
-                    .lhs = lhs,
-                    .rhs = undefined,
-                },
-            }),
-            .invalid_periodasterisks => {
-                try p.warn(.asterisk_after_ptr_deref);
-                return p.addNode(.{
-                    .tag = .deref,
-                    .main_token = p.nextToken(),
-                    .data = .{
-                        .lhs = lhs,
-                        .rhs = undefined,
-                    },
-                });
-            },
-            .period => switch (p.token_tags[p.tok_i + 1]) {
-                .identifier => return p.addNode(.{
-                    .tag = .field_access,
-                    .main_token = p.nextToken(),
-                    .data = .{
-                        .lhs = lhs,
-                        .rhs = p.nextToken(),
-                    },
-                }),
-                .question_mark => return p.addNode(.{
-                    .tag = .unwrap_optional,
-                    .main_token = p.nextToken(),
-                    .data = .{
-                        .lhs = lhs,
-                        .rhs = p.nextToken(),
-                    },
-                }),
-                .l_brace => {
-                    // this a misplaced `.{`, handle the error somewhere else
-                    return null_node;
-                },
-                else => {
-                    p.tok_i += 1;
-                    try p.warn(.expected_suffix_op);
-                    return null_node;
-                },
-            },
-            else => return null_node,
-        }
-    }
-
-    /// Caller must have already verified the first token.
-    ///
-    /// ContainerDeclAuto <- ContainerDeclType LBRACE container_doc_comment? ContainerMembers RBRACE
-    ///
-    /// ContainerDeclType
-    ///     <- KEYWORD_struct (LPAREN Expr RPAREN)?
-    ///      / KEYWORD_opaque
-    ///      / KEYWORD_enum (LPAREN Expr RPAREN)?
-    ///      / KEYWORD_union (LPAREN (KEYWORD_enum (LPAREN Expr RPAREN)? / Expr) RPAREN)?
-    fn parseContainerDeclAuto(p: *Parser) !Node.Index {
-        const main_token = p.nextToken();
-        const arg_expr = switch (p.token_tags[main_token]) {
-            .keyword_opaque => null_node,
-            .keyword_struct, .keyword_enum => blk: {
-                if (p.eatToken(.l_paren)) |_| {
-                    const expr = try p.expectExpr();
-                    _ = try p.expectToken(.r_paren);
-                    break :blk expr;
-                } else {
-                    break :blk null_node;
-                }
-            },
-            .keyword_union => blk: {
-                if (p.eatToken(.l_paren)) |_| {
-                    if (p.eatToken(.keyword_enum)) |_| {
-                        if (p.eatToken(.l_paren)) |_| {
-                            const enum_tag_expr = try p.expectExpr();
-                            _ = try p.expectToken(.r_paren);
-                            _ = try p.expectToken(.r_paren);
-
-                            _ = try p.expectToken(.l_brace);
-                            const members = try p.parseContainerMembers();
-                            const members_span = try members.toSpan(p);
-                            _ = try p.expectToken(.r_brace);
-                            return p.addNode(.{
-                                .tag = switch (members.trailing) {
-                                    true => .tagged_union_enum_tag_trailing,
-                                    false => .tagged_union_enum_tag,
-                                },
-                                .main_token = main_token,
-                                .data = .{
-                                    .lhs = enum_tag_expr,
-                                    .rhs = try p.addExtra(members_span),
-                                },
-                            });
-                        } else {
-                            _ = try p.expectToken(.r_paren);
-
-                            _ = try p.expectToken(.l_brace);
-                            const members = try p.parseContainerMembers();
-                            _ = try p.expectToken(.r_brace);
-                            if (members.len <= 2) {
-                                return p.addNode(.{
-                                    .tag = switch (members.trailing) {
-                                        true => .tagged_union_two_trailing,
-                                        false => .tagged_union_two,
-                                    },
-                                    .main_token = main_token,
-                                    .data = .{
-                                        .lhs = members.lhs,
-                                        .rhs = members.rhs,
-                                    },
-                                });
-                            } else {
-                                const span = try members.toSpan(p);
-                                return p.addNode(.{
-                                    .tag = switch (members.trailing) {
-                                        true => .tagged_union_trailing,
-                                        false => .tagged_union,
-                                    },
-                                    .main_token = main_token,
-                                    .data = .{
-                                        .lhs = span.start,
-                                        .rhs = span.end,
-                                    },
-                                });
-                            }
-                        }
-                    } else {
-                        const expr = try p.expectExpr();
-                        _ = try p.expectToken(.r_paren);
-                        break :blk expr;
-                    }
-                } else {
-                    break :blk null_node;
-                }
-            },
-            else => {
-                p.tok_i -= 1;
-                return p.fail(.expected_container);
-            },
-        };
-        _ = try p.expectToken(.l_brace);
-        const members = try p.parseContainerMembers();
-        _ = try p.expectToken(.r_brace);
-        if (arg_expr == 0) {
-            if (members.len <= 2) {
-                return p.addNode(.{
-                    .tag = switch (members.trailing) {
-                        true => .container_decl_two_trailing,
-                        false => .container_decl_two,
-                    },
-                    .main_token = main_token,
-                    .data = .{
-                        .lhs = members.lhs,
-                        .rhs = members.rhs,
-                    },
-                });
-            } else {
-                const span = try members.toSpan(p);
-                return p.addNode(.{
-                    .tag = switch (members.trailing) {
-                        true => .container_decl_trailing,
-                        false => .container_decl,
-                    },
-                    .main_token = main_token,
-                    .data = .{
-                        .lhs = span.start,
-                        .rhs = span.end,
-                    },
-                });
-            }
-        } else {
-            const span = try members.toSpan(p);
-            return p.addNode(.{
-                .tag = switch (members.trailing) {
-                    true => .container_decl_arg_trailing,
-                    false => .container_decl_arg,
-                },
-                .main_token = main_token,
-                .data = .{
-                    .lhs = arg_expr,
-                    .rhs = try p.addExtra(Node.SubRange{
-                        .start = span.start,
-                        .end = span.end,
-                    }),
-                },
-            });
-        }
-    }
-
-    /// Give a helpful error message for those transitioning from
-    /// C's 'struct Foo {};' to Zig's 'const Foo = struct {};'.
-    fn parseCStyleContainer(p: *Parser) Error!bool {
-        const main_token = p.tok_i;
-        switch (p.token_tags[p.tok_i]) {
-            .keyword_enum, .keyword_union, .keyword_struct => {},
-            else => return false,
-        }
-        const identifier = p.tok_i + 1;
-        if (p.token_tags[identifier] != .identifier) return false;
-        p.tok_i += 2;
-
-        try p.warnMsg(.{
-            .tag = .c_style_container,
-            .token = identifier,
-            .extra = .{ .expected_tag = p.token_tags[main_token] },
-        });
-        try p.warnMsg(.{
-            .tag = .zig_style_container,
-            .is_note = true,
-            .token = identifier,
-            .extra = .{ .expected_tag = p.token_tags[main_token] },
-        });
-
-        _ = try p.expectToken(.l_brace);
-        _ = try p.parseContainerMembers();
-        _ = try p.expectToken(.r_brace);
-        try p.expectSemicolon(.expected_semi_after_decl, true);
-        return true;
-    }
-
-    /// Holds temporary data until we are ready to construct the full ContainerDecl AST node.
-    ///
-    /// ByteAlign <- KEYWORD_align LPAREN Expr RPAREN
-    fn parseByteAlign(p: *Parser) !Node.Index {
-        _ = p.eatToken(.keyword_align) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const expr = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        return expr;
-    }
-
-    /// SwitchProngList <- (SwitchProng COMMA)* SwitchProng?
-    fn parseSwitchProngList(p: *Parser) !Node.SubRange {
-        const scratch_top = p.scratch.items.len;
-        defer p.scratch.shrinkRetainingCapacity(scratch_top);
-
-        while (true) {
-            const item = try parseSwitchProng(p);
-            if (item == 0) break;
-
-            try p.scratch.append(p.gpa, item);
-
-            switch (p.token_tags[p.tok_i]) {
-                .comma => p.tok_i += 1,
-                // All possible delimiters.
-                .colon, .r_paren, .r_brace, .r_bracket => break,
-                // Likely just a missing comma; give error but continue parsing.
-                else => try p.warn(.expected_comma_after_switch_prong),
-            }
-        }
-        return p.listToSpan(p.scratch.items[scratch_top..]);
-    }
-
-    /// ParamDeclList <- (ParamDecl COMMA)* ParamDecl?
-    fn parseParamDeclList(p: *Parser) !SmallSpan {
-        _ = try p.expectToken(.l_paren);
-        const scratch_top = p.scratch.items.len;
-        defer p.scratch.shrinkRetainingCapacity(scratch_top);
-        var varargs: union(enum) { none, seen, nonfinal: TokenIndex } = .none;
-        while (true) {
-            if (p.eatToken(.r_paren)) |_| break;
-            if (varargs == .seen) varargs = .{ .nonfinal = p.tok_i };
-            const param = try p.expectParamDecl();
-            if (param != 0) {
-                try p.scratch.append(p.gpa, param);
-            } else if (p.token_tags[p.tok_i - 1] == .ellipsis3) {
-                if (varargs == .none) varargs = .seen;
-            }
-            switch (p.token_tags[p.tok_i]) {
-                .comma => p.tok_i += 1,
-                .r_paren => {
-                    p.tok_i += 1;
-                    break;
-                },
-                .colon, .r_brace, .r_bracket => return p.failExpected(.r_paren),
-                // Likely just a missing comma; give error but continue parsing.
-                else => try p.warn(.expected_comma_after_param),
-            }
-        }
-        if (varargs == .nonfinal) {
-            try p.warnMsg(.{ .tag = .varargs_nonfinal, .token = varargs.nonfinal });
-        }
-        const params = p.scratch.items[scratch_top..];
-        return switch (params.len) {
-            0 => SmallSpan{ .zero_or_one = 0 },
-            1 => SmallSpan{ .zero_or_one = params[0] },
-            else => SmallSpan{ .multi = try p.listToSpan(params) },
-        };
-    }
-
-    /// FnCallArguments <- LPAREN ExprList RPAREN
-    ///
-    /// ExprList <- (Expr COMMA)* Expr?
-    fn parseBuiltinCall(p: *Parser) !Node.Index {
-        const builtin_token = p.assertToken(.builtin);
-        if (p.token_tags[p.nextToken()] != .l_paren) {
-            p.tok_i -= 1;
-            try p.warn(.expected_param_list);
-            // Pretend this was an identifier so we can continue parsing.
-            return p.addNode(.{
-                .tag = .identifier,
-                .main_token = builtin_token,
-                .data = .{
-                    .lhs = undefined,
-                    .rhs = undefined,
-                },
-            });
-        }
-        const scratch_top = p.scratch.items.len;
-        defer p.scratch.shrinkRetainingCapacity(scratch_top);
-        while (true) {
-            if (p.eatToken(.r_paren)) |_| break;
-            const param = try p.expectExpr();
-            try p.scratch.append(p.gpa, param);
-            switch (p.token_tags[p.tok_i]) {
-                .comma => p.tok_i += 1,
-                .r_paren => {
-                    p.tok_i += 1;
-                    break;
-                },
-                // Likely just a missing comma; give error but continue parsing.
-                else => try p.warn(.expected_comma_after_arg),
-            }
-        }
-        const comma = (p.token_tags[p.tok_i - 2] == .comma);
-        const params = p.scratch.items[scratch_top..];
-        switch (params.len) {
-            0 => return p.addNode(.{
-                .tag = .builtin_call_two,
-                .main_token = builtin_token,
-                .data = .{
-                    .lhs = 0,
-                    .rhs = 0,
-                },
-            }),
-            1 => return p.addNode(.{
-                .tag = if (comma) .builtin_call_two_comma else .builtin_call_two,
-                .main_token = builtin_token,
-                .data = .{
-                    .lhs = params[0],
-                    .rhs = 0,
-                },
-            }),
-            2 => return p.addNode(.{
-                .tag = if (comma) .builtin_call_two_comma else .builtin_call_two,
-                .main_token = builtin_token,
-                .data = .{
-                    .lhs = params[0],
-                    .rhs = params[1],
-                },
-            }),
-            else => {
-                const span = try p.listToSpan(params);
-                return p.addNode(.{
-                    .tag = if (comma) .builtin_call_comma else .builtin_call,
-                    .main_token = builtin_token,
-                    .data = .{
-                        .lhs = span.start,
-                        .rhs = span.end,
-                    },
-                });
-            },
-        }
-    }
-
-    /// IfPrefix <- KEYWORD_if LPAREN Expr RPAREN PtrPayload?
-    fn parseIf(p: *Parser, comptime bodyParseFn: fn (p: *Parser) Error!Node.Index) !Node.Index {
-        const if_token = p.eatToken(.keyword_if) orelse return null_node;
-        _ = try p.expectToken(.l_paren);
-        const condition = try p.expectExpr();
-        _ = try p.expectToken(.r_paren);
-        _ = try p.parsePtrPayload();
-
-        const then_expr = try bodyParseFn(p);
-        assert(then_expr != 0);
-
-        _ = p.eatToken(.keyword_else) orelse return p.addNode(.{
-            .tag = .if_simple,
-            .main_token = if_token,
-            .data = .{
-                .lhs = condition,
-                .rhs = then_expr,
-            },
-        });
-        _ = try p.parsePayload();
-        const else_expr = try bodyParseFn(p);
-        assert(then_expr != 0);
-
-        return p.addNode(.{
-            .tag = .@"if",
-            .main_token = if_token,
-            .data = .{
-                .lhs = condition,
-                .rhs = try p.addExtra(Node.If{
-                    .then_expr = then_expr,
-                    .else_expr = else_expr,
-                }),
-            },
-        });
-    }
-
-    /// Skips over doc comment tokens. Returns the first one, if any.
-    fn eatDocComments(p: *Parser) !?TokenIndex {
-        if (p.eatToken(.doc_comment)) |tok| {
-            var first_line = tok;
-            if (tok > 0 and tokensOnSameLine(p, tok - 1, tok)) {
-                try p.warnMsg(.{
-                    .tag = .same_line_doc_comment,
-                    .token = tok,
-                });
-                first_line = p.eatToken(.doc_comment) orelse return null;
-            }
-            while (p.eatToken(.doc_comment)) |_| {}
-            return first_line;
-        }
-        return null;
-    }
-
-    fn tokensOnSameLine(p: *Parser, token1: TokenIndex, token2: TokenIndex) bool {
-        return std.mem.indexOfScalar(u8, p.source[p.token_starts[token1]..p.token_starts[token2]], '\n') == null;
-    }
-
-    fn eatToken(p: *Parser, tag: Token.Tag) ?TokenIndex {
-        return if (p.token_tags[p.tok_i] == tag) p.nextToken() else null;
-    }
-
-    fn assertToken(p: *Parser, tag: Token.Tag) TokenIndex {
-        const token = p.nextToken();
-        assert(p.token_tags[token] == tag);
-        return token;
-    }
-
-    fn expectToken(p: *Parser, tag: Token.Tag) Error!TokenIndex {
-        if (p.token_tags[p.tok_i] != tag) {
-            return p.failMsg(.{
-                .tag = .expected_token,
-                .token = p.tok_i,
-                .extra = .{ .expected_tag = tag },
-            });
-        }
-        return p.nextToken();
-    }
-
-    fn expectSemicolon(p: *Parser, error_tag: AstError.Tag, recoverable: bool) Error!void {
-        if (p.token_tags[p.tok_i] == .semicolon) {
-            _ = p.nextToken();
-            return;
-        }
-        try p.warn(error_tag);
-        if (!recoverable) return error.ParseError;
-    }
-
-    fn nextToken(p: *Parser) TokenIndex {
-        const result = p.tok_i;
-        p.tok_i += 1;
-        return result;
-    }
-};
-
-test {
-    _ = @import("parser_test.zig");
-}

lib/std/zig/parser_test.zig

@@ -6073,7 +6073,7 @@ var fixed_buffer_mem: [100 * 1024]u8 = undefined;
 fn testParse(source: [:0]const u8, allocator: mem.Allocator, anything_changed: *bool) ![]u8 {
     const stderr = io.getStdErr().writer();
 
-    var tree = try std.zig.parse(allocator, source);
+    var tree = try std.zig.Ast.parse(allocator, source, .zig);
     defer tree.deinit(allocator);
 
     for (tree.errors) |parse_error| {
@@ -6124,7 +6124,7 @@ fn testCanonical(source: [:0]const u8) !void {
 const Error = std.zig.Ast.Error.Tag;
 
 fn testError(source: [:0]const u8, expected_errors: []const Error) !void {
-    var tree = try std.zig.parse(std.testing.allocator, source);
+    var tree = try std.zig.Ast.parse(std.testing.allocator, source, .zig);
     defer tree.deinit(std.testing.allocator);
 
     std.testing.expectEqual(expected_errors.len, tree.errors.len) catch |err| {

lib/std/zig/perf_test.zig

@@ -1,7 +1,6 @@
 const std = @import("std");
 const mem = std.mem;
 const Tokenizer = std.zig.Tokenizer;
-const Parser = std.zig.Parser;
 const io = std.io;
 const fmtIntSizeBin = std.fmt.fmtIntSizeBin;
 
@@ -34,6 +33,6 @@ pub fn main() !void {
 fn testOnce() usize {
     var fixed_buf_alloc = std.heap.FixedBufferAllocator.init(fixed_buffer_mem[0..]);
     var allocator = fixed_buf_alloc.allocator();
-    _ = std.zig.parse(allocator, source) catch @panic("parse failure");
+    _ = std.zig.Ast.parse(allocator, source, .zig) catch @panic("parse failure");
     return fixed_buf_alloc.end_index;
 }

src/Compilation.zig

@@ -385,7 +385,7 @@ pub const AllErrors = struct {
             count: u32 = 1,
             /// Does not include the trailing newline.
             source_line: ?[]const u8,
-            notes: []Message = &.{},
+            notes: []const Message = &.{},
             reference_trace: []Message = &.{},
 
             /// Splits the error message up into lines to properly indent them

src/Manifest.zig

@@ -0,0 +1,499 @@
+pub const basename = "build.zig.zon";
+pub const Hash = std.crypto.hash.sha2.Sha256;
+
+pub const Dependency = struct {
+    url: []const u8,
+    url_tok: Ast.TokenIndex,
+    hash: ?[]const u8,
+    hash_tok: Ast.TokenIndex,
+};
+
+pub const ErrorMessage = struct {
+    msg: []const u8,
+    tok: Ast.TokenIndex,
+    off: u32,
+};
+
+pub const MultihashFunction = enum(u16) {
+    identity = 0x00,
+    sha1 = 0x11,
+    @"sha2-256" = 0x12,
+    @"sha2-512" = 0x13,
+    @"sha3-512" = 0x14,
+    @"sha3-384" = 0x15,
+    @"sha3-256" = 0x16,
+    @"sha3-224" = 0x17,
+    @"sha2-384" = 0x20,
+    @"sha2-256-trunc254-padded" = 0x1012,
+    @"sha2-224" = 0x1013,
+    @"sha2-512-224" = 0x1014,
+    @"sha2-512-256" = 0x1015,
+    @"blake2b-256" = 0xb220,
+    _,
+};
+
+pub const multihash_function: MultihashFunction = switch (Hash) {
+    std.crypto.hash.sha2.Sha256 => .@"sha2-256",
+    else => @compileError("unreachable"),
+};
+comptime {
+    // We avoid unnecessary uleb128 code in hexDigest by asserting here the
+    // values are small enough to be contained in the one-byte encoding.
+    assert(@enumToInt(multihash_function) < 127);
+    assert(Hash.digest_length < 127);
+}
+pub const multihash_len = 1 + 1 + Hash.digest_length;
+
+name: []const u8,
+version: std.SemanticVersion,
+dependencies: std.StringArrayHashMapUnmanaged(Dependency),
+
+errors: []ErrorMessage,
+arena_state: std.heap.ArenaAllocator.State,
+
+pub const Error = Allocator.Error;
+
+pub fn parse(gpa: Allocator, ast: std.zig.Ast) Error!Manifest {
+    const node_tags = ast.nodes.items(.tag);
+    const node_datas = ast.nodes.items(.data);
+    assert(node_tags[0] == .root);
+    const main_node_index = node_datas[0].lhs;
+
+    var arena_instance = std.heap.ArenaAllocator.init(gpa);
+    errdefer arena_instance.deinit();
+
+    var p: Parse = .{
+        .gpa = gpa,
+        .ast = ast,
+        .arena = arena_instance.allocator(),
+        .errors = .{},
+
+        .name = undefined,
+        .version = undefined,
+        .dependencies = .{},
+        .buf = .{},
+    };
+    defer p.buf.deinit(gpa);
+    defer p.errors.deinit(gpa);
+    defer p.dependencies.deinit(gpa);
+
+    p.parseRoot(main_node_index) catch |err| switch (err) {
+        error.ParseFailure => assert(p.errors.items.len > 0),
+        else => |e| return e,
+    };
+
+    return .{
+        .name = p.name,
+        .version = p.version,
+        .dependencies = try p.dependencies.clone(p.arena),
+        .errors = try p.arena.dupe(ErrorMessage, p.errors.items),
+        .arena_state = arena_instance.state,
+    };
+}
+
+pub fn deinit(man: *Manifest, gpa: Allocator) void {
+    man.arena_state.promote(gpa).deinit();
+    man.* = undefined;
+}
+
+const hex_charset = "0123456789abcdef";
+
+pub fn hex64(x: u64) [16]u8 {
+    var result: [16]u8 = undefined;
+    var i: usize = 0;
+    while (i < 8) : (i += 1) {
+        const byte = @truncate(u8, x >> @intCast(u6, 8 * i));
+        result[i * 2 + 0] = hex_charset[byte >> 4];
+        result[i * 2 + 1] = hex_charset[byte & 15];
+    }
+    return result;
+}
+
+test hex64 {
+    const s = "[" ++ hex64(0x12345678_abcdef00) ++ "]";
+    try std.testing.expectEqualStrings("[00efcdab78563412]", s);
+}
+
+pub fn hexDigest(digest: [Hash.digest_length]u8) [multihash_len * 2]u8 {
+    var result: [multihash_len * 2]u8 = undefined;
+
+    result[0] = hex_charset[@enumToInt(multihash_function) >> 4];
+    result[1] = hex_charset[@enumToInt(multihash_function) & 15];
+
+    result[2] = hex_charset[Hash.digest_length >> 4];
+    result[3] = hex_charset[Hash.digest_length & 15];
+
+    for (digest) |byte, i| {
+        result[4 + i * 2] = hex_charset[byte >> 4];
+        result[5 + i * 2] = hex_charset[byte & 15];
+    }
+    return result;
+}
+
+const Parse = struct {
+    gpa: Allocator,
+    ast: std.zig.Ast,
+    arena: Allocator,
+    buf: std.ArrayListUnmanaged(u8),
+    errors: std.ArrayListUnmanaged(ErrorMessage),
+
+    name: []const u8,
+    version: std.SemanticVersion,
+    dependencies: std.StringArrayHashMapUnmanaged(Dependency),
+
+    const InnerError = error{ ParseFailure, OutOfMemory };
+
+    fn parseRoot(p: *Parse, node: Ast.Node.Index) !void {
+        const ast = p.ast;
+        const main_tokens = ast.nodes.items(.main_token);
+        const main_token = main_tokens[node];
+
+        var buf: [2]Ast.Node.Index = undefined;
+        const struct_init = ast.fullStructInit(&buf, node) orelse {
+            return fail(p, main_token, "expected top level expression to be a struct", .{});
+        };
+
+        var have_name = false;
+        var have_version = false;
+
+        for (struct_init.ast.fields) |field_init| {
+            const name_token = ast.firstToken(field_init) - 2;
+            const field_name = try identifierTokenString(p, name_token);
+            // We could get fancy with reflection and comptime logic here but doing
+            // things manually provides an opportunity to do any additional verification
+            // that is desirable on a per-field basis.
+            if (mem.eql(u8, field_name, "dependencies")) {
+                try parseDependencies(p, field_init);
+            } else if (mem.eql(u8, field_name, "name")) {
+                p.name = try parseString(p, field_init);
+                have_name = true;
+            } else if (mem.eql(u8, field_name, "version")) {
+                const version_text = try parseString(p, field_init);
+                p.version = std.SemanticVersion.parse(version_text) catch |err| v: {
+                    try appendError(p, main_tokens[field_init], "unable to parse semantic version: {s}", .{@errorName(err)});
+                    break :v undefined;
+                };
+                have_version = true;
+            } else {
+                // Ignore unknown fields so that we can add fields in future zig
+                // versions without breaking older zig versions.
+            }
+        }
+
+        if (!have_name) {
+            try appendError(p, main_token, "missing top-level 'name' field", .{});
+        }
+
+        if (!have_version) {
+            try appendError(p, main_token, "missing top-level 'version' field", .{});
+        }
+    }
+
+    fn parseDependencies(p: *Parse, node: Ast.Node.Index) !void {
+        const ast = p.ast;
+        const main_tokens = ast.nodes.items(.main_token);
+
+        var buf: [2]Ast.Node.Index = undefined;
+        const struct_init = ast.fullStructInit(&buf, node) orelse {
+            const tok = main_tokens[node];
+            return fail(p, tok, "expected dependencies expression to be a struct", .{});
+        };
+
+        for (struct_init.ast.fields) |field_init| {
+            const name_token = ast.firstToken(field_init) - 2;
+            const dep_name = try identifierTokenString(p, name_token);
+            const dep = try parseDependency(p, field_init);
+            try p.dependencies.put(p.gpa, dep_name, dep);
+        }
+    }
+
+    fn parseDependency(p: *Parse, node: Ast.Node.Index) !Dependency {
+        const ast = p.ast;
+        const main_tokens = ast.nodes.items(.main_token);
+
+        var buf: [2]Ast.Node.Index = undefined;
+        const struct_init = ast.fullStructInit(&buf, node) orelse {
+            const tok = main_tokens[node];
+            return fail(p, tok, "expected dependency expression to be a struct", .{});
+        };
+
+        var dep: Dependency = .{
+            .url = undefined,
+            .url_tok = undefined,
+            .hash = null,
+            .hash_tok = undefined,
+        };
+        var have_url = false;
+
+        for (struct_init.ast.fields) |field_init| {
+            const name_token = ast.firstToken(field_init) - 2;
+            const field_name = try identifierTokenString(p, name_token);
+            // We could get fancy with reflection and comptime logic here but doing
+            // things manually provides an opportunity to do any additional verification
+            // that is desirable on a per-field basis.
+            if (mem.eql(u8, field_name, "url")) {
+                dep.url = parseString(p, field_init) catch |err| switch (err) {
+                    error.ParseFailure => continue,
+                    else => |e| return e,
+                };
+                dep.url_tok = main_tokens[field_init];
+                have_url = true;
+            } else if (mem.eql(u8, field_name, "hash")) {
+                dep.hash = parseHash(p, field_init) catch |err| switch (err) {
+                    error.ParseFailure => continue,
+                    else => |e| return e,
+                };
+                dep.hash_tok = main_tokens[field_init];
+            } else {
+                // Ignore unknown fields so that we can add fields in future zig
+                // versions without breaking older zig versions.
+            }
+        }
+
+        if (!have_url) {
+            try appendError(p, main_tokens[node], "dependency is missing 'url' field", .{});
+        }
+
+        return dep;
+    }
+
+    fn parseString(p: *Parse, node: Ast.Node.Index) ![]const u8 {
+        const ast = p.ast;
+        const node_tags = ast.nodes.items(.tag);
+        const main_tokens = ast.nodes.items(.main_token);
+        if (node_tags[node] != .string_literal) {
+            return fail(p, main_tokens[node], "expected string literal", .{});
+        }
+        const str_lit_token = main_tokens[node];
+        const token_bytes = ast.tokenSlice(str_lit_token);
+        p.buf.clearRetainingCapacity();
+        try parseStrLit(p, str_lit_token, &p.buf, token_bytes, 0);
+        const duped = try p.arena.dupe(u8, p.buf.items);
+        return duped;
+    }
+
+    fn parseHash(p: *Parse, node: Ast.Node.Index) ![]const u8 {
+        const ast = p.ast;
+        const main_tokens = ast.nodes.items(.main_token);
+        const tok = main_tokens[node];
+        const h = try parseString(p, node);
+
+        if (h.len >= 2) {
+            const their_multihash_func = std.fmt.parseInt(u8, h[0..2], 16) catch |err| {
+                return fail(p, tok, "invalid multihash value: unable to parse hash function: {s}", .{
+                    @errorName(err),
+                });
+            };
+            if (@intToEnum(MultihashFunction, their_multihash_func) != multihash_function) {
+                return fail(p, tok, "unsupported hash function: only sha2-256 is supported", .{});
+            }
+        }
+
+        const hex_multihash_len = 2 * Manifest.multihash_len;
+        if (h.len != hex_multihash_len) {
+            return fail(p, tok, "wrong hash size. expected: {d}, found: {d}", .{
+                hex_multihash_len, h.len,
+            });
+        }
+
+        return h;
+    }
+
+    /// TODO: try to DRY this with AstGen.identifierTokenString
+    fn identifierTokenString(p: *Parse, token: Ast.TokenIndex) InnerError![]const u8 {
+        const ast = p.ast;
+        const token_tags = ast.tokens.items(.tag);
+        assert(token_tags[token] == .identifier);
+        const ident_name = ast.tokenSlice(token);
+        if (!mem.startsWith(u8, ident_name, "@")) {
+            return ident_name;
+        }
+        p.buf.clearRetainingCapacity();
+        try parseStrLit(p, token, &p.buf, ident_name, 1);
+        const duped = try p.arena.dupe(u8, p.buf.items);
+        return duped;
+    }
+
+    /// TODO: try to DRY this with AstGen.parseStrLit
+    fn parseStrLit(
+        p: *Parse,
+        token: Ast.TokenIndex,
+        buf: *std.ArrayListUnmanaged(u8),
+        bytes: []const u8,
+        offset: u32,
+    ) InnerError!void {
+        const raw_string = bytes[offset..];
+        var buf_managed = buf.toManaged(p.gpa);
+        const result = std.zig.string_literal.parseWrite(buf_managed.writer(), raw_string);
+        buf.* = buf_managed.moveToUnmanaged();
+        switch (try result) {
+            .success => {},
+            .failure => |err| try p.appendStrLitError(err, token, bytes, offset),
+        }
+    }
+
+    /// TODO: try to DRY this with AstGen.failWithStrLitError
+    fn appendStrLitError(
+        p: *Parse,
+        err: std.zig.string_literal.Error,
+        token: Ast.TokenIndex,
+        bytes: []const u8,
+        offset: u32,
+    ) Allocator.Error!void {
+        const raw_string = bytes[offset..];
+        switch (err) {
+            .invalid_escape_character => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "invalid escape character: '{c}'",
+                    .{raw_string[bad_index]},
+                );
+            },
+            .expected_hex_digit => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "expected hex digit, found '{c}'",
+                    .{raw_string[bad_index]},
+                );
+            },
+            .empty_unicode_escape_sequence => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "empty unicode escape sequence",
+                    .{},
+                );
+            },
+            .expected_hex_digit_or_rbrace => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "expected hex digit or '}}', found '{c}'",
+                    .{raw_string[bad_index]},
+                );
+            },
+            .invalid_unicode_codepoint => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "unicode escape does not correspond to a valid codepoint",
+                    .{},
+                );
+            },
+            .expected_lbrace => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "expected '{{', found '{c}",
+                    .{raw_string[bad_index]},
+                );
+            },
+            .expected_rbrace => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "expected '}}', found '{c}",
+                    .{raw_string[bad_index]},
+                );
+            },
+            .expected_single_quote => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "expected single quote ('), found '{c}",
+                    .{raw_string[bad_index]},
+                );
+            },
+            .invalid_character => |bad_index| {
+                try p.appendErrorOff(
+                    token,
+                    offset + @intCast(u32, bad_index),
+                    "invalid byte in string or character literal: '{c}'",
+                    .{raw_string[bad_index]},
+                );
+            },
+        }
+    }
+
+    fn fail(
+        p: *Parse,
+        tok: Ast.TokenIndex,
+        comptime fmt: []const u8,
+        args: anytype,
+    ) InnerError {
+        try appendError(p, tok, fmt, args);
+        return error.ParseFailure;
+    }
+
+    fn appendError(p: *Parse, tok: Ast.TokenIndex, comptime fmt: []const u8, args: anytype) !void {
+        return appendErrorOff(p, tok, 0, fmt, args);
+    }
+
+    fn appendErrorOff(
+        p: *Parse,
+        tok: Ast.TokenIndex,
+        byte_offset: u32,
+        comptime fmt: []const u8,
+        args: anytype,
+    ) Allocator.Error!void {
+        try p.errors.append(p.gpa, .{
+            .msg = try std.fmt.allocPrint(p.arena, fmt, args),
+            .tok = tok,
+            .off = byte_offset,
+        });
+    }
+};
+
+const Manifest = @This();
+const std = @import("std");
+const mem = std.mem;
+const Allocator = std.mem.Allocator;
+const assert = std.debug.assert;
+const Ast = std.zig.Ast;
+const testing = std.testing;
+
+test "basic" {
+    const gpa = testing.allocator;
+
+    const example =
+        \\.{
+        \\    .name = "foo",
+        \\    .version = "3.2.1",
+        \\    .dependencies = .{
+        \\        .bar = .{
+        \\            .url = "https://example.com/baz.tar.gz",
+        \\            .hash = "1220f1b680b6065fcfc94fe777f22e73bcb7e2767e5f4d99d4255fe76ded69c7a35f",
+        \\        },
+        \\    },
+        \\}
+    ;
+
+    var ast = try std.zig.Ast.parse(gpa, example, .zon);
+    defer ast.deinit(gpa);
+
+    try testing.expect(ast.errors.len == 0);
+
+    var manifest = try Manifest.parse(gpa, ast);
+    defer manifest.deinit(gpa);
+
+    try testing.expectEqualStrings("foo", manifest.name);
+
+    try testing.expectEqual(@as(std.SemanticVersion, .{
+        .major = 3,
+        .minor = 2,
+        .patch = 1,
+    }), manifest.version);
+
+    try testing.expect(manifest.dependencies.count() == 1);
+    try testing.expectEqualStrings("bar", manifest.dependencies.keys()[0]);
+    try testing.expectEqualStrings(
+        "https://example.com/baz.tar.gz",
+        manifest.dependencies.values()[0].url,
+    );
+    try testing.expectEqualStrings(
+        "1220f1b680b6065fcfc94fe777f22e73bcb7e2767e5f4d99d4255fe76ded69c7a35f",
+        manifest.dependencies.values()[0].hash orelse return error.TestFailed,
+    );
+}

src/Module.zig

@@ -2057,7 +2057,7 @@ pub const File = struct {
         if (file.tree_loaded) return &file.tree;
 
         const source = try file.getSource(gpa);
-        file.tree = try std.zig.parse(gpa, source.bytes);
+        file.tree = try Ast.parse(gpa, source.bytes, .zig);
         file.tree_loaded = true;
         return &file.tree;
     }
@@ -3662,7 +3662,7 @@ pub fn astGenFile(mod: *Module, file: *File) !void {
     file.source = source;
     file.source_loaded = true;
 
-    file.tree = try std.zig.parse(gpa, source);
+    file.tree = try Ast.parse(gpa, source, .zig);
     defer if (!file.tree_loaded) file.tree.deinit(gpa);
 
     if (file.tree.errors.len != 0) {
@@ -3977,7 +3977,7 @@ pub fn populateBuiltinFile(mod: *Module) !void {
         else => |e| return e,
     }
 
-    file.tree = try std.zig.parse(gpa, file.source);
+    file.tree = try Ast.parse(gpa, file.source, .zig);
     file.tree_loaded = true;
     assert(file.tree.errors.len == 0); // builtin.zig must parse
 

src/Package.zig

@@ -6,8 +6,8 @@ const fs = std.fs;
 const mem = std.mem;
 const Allocator = mem.Allocator;
 const assert = std.debug.assert;
-const Hash = std.crypto.hash.sha2.Sha256;
 const log = std.log.scoped(.package);
+const main = @import("main.zig");
 
 const Compilation = @import("Compilation.zig");
 const Module = @import("Module.zig");
@@ -15,6 +15,7 @@ const ThreadPool = @import("ThreadPool.zig");
 const WaitGroup = @import("WaitGroup.zig");
 const Cache = @import("Cache.zig");
 const build_options = @import("build_options");
+const Manifest = @import("Manifest.zig");
 
 pub const Table = std.StringHashMapUnmanaged(*Package);
 
@@ -141,10 +142,10 @@ pub fn addAndAdopt(parent: *Package, gpa: Allocator, child: *Package) !void {
 }
 
 pub const build_zig_basename = "build.zig";
-pub const ini_basename = build_zig_basename ++ ".ini";
 
 pub fn fetchAndAddDependencies(
     pkg: *Package,
+    arena: Allocator,
     thread_pool: *ThreadPool,
     http_client: *std.http.Client,
     directory: Compilation.Directory,
@@ -153,89 +154,77 @@ pub fn fetchAndAddDependencies(
     dependencies_source: *std.ArrayList(u8),
     build_roots_source: *std.ArrayList(u8),
     name_prefix: []const u8,
+    color: main.Color,
 ) !void {
     const max_bytes = 10 * 1024 * 1024;
     const gpa = thread_pool.allocator;
-    const build_zig_ini = directory.handle.readFileAlloc(gpa, ini_basename, max_bytes) catch |err| switch (err) {
+    const build_zig_zon_bytes = directory.handle.readFileAllocOptions(
+        arena,
+        Manifest.basename,
+        max_bytes,
+        null,
+        1,
+        0,
+    ) catch |err| switch (err) {
         error.FileNotFound => {
             // Handle the same as no dependencies.
             return;
         },
         else => |e| return e,
     };
-    defer gpa.free(build_zig_ini);
 
-    const ini: std.Ini = .{ .bytes = build_zig_ini };
-    var any_error = false;
-    var it = ini.iterateSection("\n[dependency]\n");
-    while (it.next()) |dep| {
-        var line_it = mem.split(u8, dep, "\n");
-        var opt_name: ?[]const u8 = null;
-        var opt_url: ?[]const u8 = null;
-        var expected_hash: ?[]const u8 = null;
-        while (line_it.next()) |kv| {
-            const eq_pos = mem.indexOfScalar(u8, kv, '=') orelse continue;
-            const key = kv[0..eq_pos];
-            const value = kv[eq_pos + 1 ..];
-            if (mem.eql(u8, key, "name")) {
-                opt_name = value;
-            } else if (mem.eql(u8, key, "url")) {
-                opt_url = value;
-            } else if (mem.eql(u8, key, "hash")) {
-                expected_hash = value;
-            } else {
-                const loc = std.zig.findLineColumn(ini.bytes, @ptrToInt(key.ptr) - @ptrToInt(ini.bytes.ptr));
-                std.log.warn("{s}/{s}:{d}:{d} unrecognized key: '{s}'", .{
-                    directory.path orelse ".",
-                    "build.zig.ini",
-                    loc.line,
-                    loc.column,
-                    key,
-                });
-            }
+    var ast = try std.zig.Ast.parse(gpa, build_zig_zon_bytes, .zon);
+    defer ast.deinit(gpa);
+
+    if (ast.errors.len > 0) {
+        const file_path = try directory.join(arena, &.{Manifest.basename});
+        try main.printErrsMsgToStdErr(gpa, arena, ast, file_path, color);
+        return error.PackageFetchFailed;
+    }
+
+    var manifest = try Manifest.parse(gpa, ast);
+    defer manifest.deinit(gpa);
+
+    if (manifest.errors.len > 0) {
+        const ttyconf: std.debug.TTY.Config = switch (color) {
+            .auto => std.debug.detectTTYConfig(std.io.getStdErr()),
+            .on => .escape_codes,
+            .off => .no_color,
+        };
+        const file_path = try directory.join(arena, &.{Manifest.basename});
+        for (manifest.errors) |msg| {
+            Report.renderErrorMessage(ast, file_path, ttyconf, msg, &.{});
         }
+        return error.PackageFetchFailed;
+    }
 
-        const name = opt_name orelse {
-            const loc = std.zig.findLineColumn(ini.bytes, @ptrToInt(dep.ptr) - @ptrToInt(ini.bytes.ptr));
-            std.log.err("{s}/{s}:{d}:{d} missing key: 'name'", .{
-                directory.path orelse ".",
-                "build.zig.ini",
-                loc.line,
-                loc.column,
-            });
-            any_error = true;
-            continue;
-        };
+    const report: Report = .{
+        .ast = &ast,
+        .directory = directory,
+        .color = color,
+        .arena = arena,
+    };
 
-        const url = opt_url orelse {
-            const loc = std.zig.findLineColumn(ini.bytes, @ptrToInt(dep.ptr) - @ptrToInt(ini.bytes.ptr));
-            std.log.err("{s}/{s}:{d}:{d} missing key: 'name'", .{
-                directory.path orelse ".",
-                "build.zig.ini",
-                loc.line,
-                loc.column,
-            });
-            any_error = true;
-            continue;
-        };
+    var any_error = false;
+    const deps_list = manifest.dependencies.values();
+    for (manifest.dependencies.keys()) |name, i| {
+        const dep = deps_list[i];
 
-        const sub_prefix = try std.fmt.allocPrint(gpa, "{s}{s}.", .{ name_prefix, name });
-        defer gpa.free(sub_prefix);
+        const sub_prefix = try std.fmt.allocPrint(arena, "{s}{s}.", .{ name_prefix, name });
         const fqn = sub_prefix[0 .. sub_prefix.len - 1];
 
         const sub_pkg = try fetchAndUnpack(
             thread_pool,
             http_client,
             global_cache_directory,
-            url,
-            expected_hash,
-            ini,
-            directory,
+            dep,
+            report,
             build_roots_source,
             fqn,
         );
 
         try pkg.fetchAndAddDependencies(
+            arena,
             thread_pool,
             http_client,
             sub_pkg.root_src_directory,
@@ -244,6 +233,7 @@ pub fn fetchAndAddDependencies(
             dependencies_source,
             build_roots_source,
             sub_prefix,
+            color,
         );
 
         try addAndAdopt(pkg, gpa, sub_pkg);
@@ -253,7 +243,7 @@ pub fn fetchAndAddDependencies(
         });
     }
 
-    if (any_error) return error.InvalidBuildZigIniFile;
+    if (any_error) return error.InvalidBuildManifestFile;
 }
 
 pub fn createFilePkg(
@@ -264,7 +254,7 @@ pub fn createFilePkg(
     contents: []const u8,
 ) !*Package {
     const rand_int = std.crypto.random.int(u64);
-    const tmp_dir_sub_path = "tmp" ++ fs.path.sep_str ++ hex64(rand_int);
+    const tmp_dir_sub_path = "tmp" ++ fs.path.sep_str ++ Manifest.hex64(rand_int);
     {
         var tmp_dir = try cache_directory.handle.makeOpenPath(tmp_dir_sub_path, .{});
         defer tmp_dir.close();
@@ -282,14 +272,73 @@ pub fn createFilePkg(
     return createWithDir(gpa, name, cache_directory, o_dir_sub_path, basename);
 }
 
+const Report = struct {
+    ast: *const std.zig.Ast,
+    directory: Compilation.Directory,
+    color: main.Color,
+    arena: Allocator,
+
+    fn fail(
+        report: Report,
+        tok: std.zig.Ast.TokenIndex,
+        comptime fmt_string: []const u8,
+        fmt_args: anytype,
+    ) error{ PackageFetchFailed, OutOfMemory } {
+        return failWithNotes(report, &.{}, tok, fmt_string, fmt_args);
+    }
+
+    fn failWithNotes(
+        report: Report,
+        notes: []const Compilation.AllErrors.Message,
+        tok: std.zig.Ast.TokenIndex,
+        comptime fmt_string: []const u8,
+        fmt_args: anytype,
+    ) error{ PackageFetchFailed, OutOfMemory } {
+        const ttyconf: std.debug.TTY.Config = switch (report.color) {
+            .auto => std.debug.detectTTYConfig(std.io.getStdErr()),
+            .on => .escape_codes,
+            .off => .no_color,
+        };
+        const file_path = try report.directory.join(report.arena, &.{Manifest.basename});
+        renderErrorMessage(report.ast.*, file_path, ttyconf, .{
+            .tok = tok,
+            .off = 0,
+            .msg = try std.fmt.allocPrint(report.arena, fmt_string, fmt_args),
+        }, notes);
+        return error.PackageFetchFailed;
+    }
+
+    fn renderErrorMessage(
+        ast: std.zig.Ast,
+        file_path: []const u8,
+        ttyconf: std.debug.TTY.Config,
+        msg: Manifest.ErrorMessage,
+        notes: []const Compilation.AllErrors.Message,
+    ) void {
+        const token_starts = ast.tokens.items(.start);
+        const start_loc = ast.tokenLocation(0, msg.tok);
+        Compilation.AllErrors.Message.renderToStdErr(.{ .src = .{
+            .msg = msg.msg,
+            .src_path = file_path,
+            .line = @intCast(u32, start_loc.line),
+            .column = @intCast(u32, start_loc.column),
+            .span = .{
+                .start = token_starts[msg.tok],
+                .end = @intCast(u32, token_starts[msg.tok] + ast.tokenSlice(msg.tok).len),
+                .main = token_starts[msg.tok] + msg.off,
+            },
+            .source_line = ast.source[start_loc.line_start..start_loc.line_end],
+            .notes = notes,
+        } }, ttyconf);
+    }
+};
+
 fn fetchAndUnpack(
     thread_pool: *ThreadPool,
     http_client: *std.http.Client,
     global_cache_directory: Compilation.Directory,
-    url: []const u8,
-    expected_hash: ?[]const u8,
-    ini: std.Ini,
-    comp_directory: Compilation.Directory,
+    dep: Manifest.Dependency,
+    report: Report,
     build_roots_source: *std.ArrayList(u8),
     fqn: []const u8,
 ) !*Package {
@@ -298,37 +347,8 @@ fn fetchAndUnpack(
 
     // Check if the expected_hash is already present in the global package
     // cache, and thereby avoid both fetching and unpacking.
-    if (expected_hash) |h| cached: {
-        const hex_multihash_len = 2 * multihash_len;
-        if (h.len >= 2) {
-            const their_multihash_func = std.fmt.parseInt(u8, h[0..2], 16) catch |err| {
-                return reportError(
-                    ini,
-                    comp_directory,
-                    h.ptr,
-                    "invalid multihash value: unable to parse hash function: {s}",
-                    .{@errorName(err)},
-                );
-            };
-            if (@intToEnum(MultihashFunction, their_multihash_func) != multihash_function) {
-                return reportError(
-                    ini,
-                    comp_directory,
-                    h.ptr,
-                    "unsupported hash function: only sha2-256 is supported",
-                    .{},
-                );
-            }
-        }
-        if (h.len != hex_multihash_len) {
-            return reportError(
-                ini,
-                comp_directory,
-                h.ptr,
-                "wrong hash size. expected: {d}, found: {d}",
-                .{ hex_multihash_len, h.len },
-            );
-        }
+    if (dep.hash) |h| cached: {
+        const hex_multihash_len = 2 * Manifest.multihash_len;
         const hex_digest = h[0..hex_multihash_len];
         const pkg_dir_sub_path = "p" ++ s ++ hex_digest;
         var pkg_dir = global_cache_directory.handle.openDir(pkg_dir_sub_path, .{}) catch |err| switch (err) {
@@ -366,10 +386,10 @@ fn fetchAndUnpack(
         return ptr;
     }
 
-    const uri = try std.Uri.parse(url);
+    const uri = try std.Uri.parse(dep.url);
 
     const rand_int = std.crypto.random.int(u64);
-    const tmp_dir_sub_path = "tmp" ++ s ++ hex64(rand_int);
+    const tmp_dir_sub_path = "tmp" ++ s ++ Manifest.hex64(rand_int);
 
     const actual_hash = a: {
         var tmp_directory: Compilation.Directory = d: {
@@ -398,13 +418,9 @@ fn fetchAndUnpack(
             // by default, so the same logic applies for buffering the reader as for gzip.
             try unpackTarball(gpa, &req, tmp_directory.handle, std.compress.xz);
         } else {
-            return reportError(
-                ini,
-                comp_directory,
-                uri.path.ptr,
-                "unknown file extension for path '{s}'",
-                .{uri.path},
-            );
+            return report.fail(dep.url_tok, "unknown file extension for path '{s}'", .{
+                uri.path,
+            });
         }
 
         // TODO: delete files not included in the package prior to computing the package hash.
@@ -415,28 +431,21 @@ fn fetchAndUnpack(
         break :a try computePackageHash(thread_pool, .{ .dir = tmp_directory.handle });
     };
 
-    const pkg_dir_sub_path = "p" ++ s ++ hexDigest(actual_hash);
+    const pkg_dir_sub_path = "p" ++ s ++ Manifest.hexDigest(actual_hash);
     try renameTmpIntoCache(global_cache_directory.handle, tmp_dir_sub_path, pkg_dir_sub_path);
 
-    const actual_hex = hexDigest(actual_hash);
-    if (expected_hash) |h| {
+    const actual_hex = Manifest.hexDigest(actual_hash);
+    if (dep.hash) |h| {
         if (!mem.eql(u8, h, &actual_hex)) {
-            return reportError(
-                ini,
-                comp_directory,
-                h.ptr,
-                "hash mismatch: expected: {s}, found: {s}",
-                .{ h, actual_hex },
-            );
+            return report.fail(dep.hash_tok, "hash mismatch: expected: {s}, found: {s}", .{
+                h, actual_hex,
+            });
         }
     } else {
-        return reportError(
-            ini,
-            comp_directory,
-            url.ptr,
-            "url field is missing corresponding hash field: hash={s}",
-            .{&actual_hex},
-        );
+        const notes: [1]Compilation.AllErrors.Message = .{.{ .plain = .{
+            .msg = try std.fmt.allocPrint(report.arena, "expected .hash = \"{s}\",", .{&actual_hex}),
+        } }};
+        return report.failWithNotes(&notes, dep.url_tok, "url field is missing corresponding hash field", .{});
     }
 
     const build_root = try global_cache_directory.join(gpa, &.{pkg_dir_sub_path});
@@ -471,29 +480,9 @@ fn unpackTarball(
     });
 }
 
-fn reportError(
-    ini: std.Ini,
-    comp_directory: Compilation.Directory,
-    src_ptr: [*]const u8,
-    comptime fmt_string: []const u8,
-    fmt_args: anytype,
-) error{PackageFetchFailed} {
-    const loc = std.zig.findLineColumn(ini.bytes, @ptrToInt(src_ptr) - @ptrToInt(ini.bytes.ptr));
-    if (comp_directory.path) |p| {
-        std.debug.print("{s}{c}{s}:{d}:{d}: error: " ++ fmt_string ++ "\n", .{
-            p, fs.path.sep, ini_basename, loc.line + 1, loc.column + 1,
-        } ++ fmt_args);
-    } else {
-        std.debug.print("{s}:{d}:{d}: error: " ++ fmt_string ++ "\n", .{
-            ini_basename, loc.line + 1, loc.column + 1,
-        } ++ fmt_args);
-    }
-    return error.PackageFetchFailed;
-}
-
 const HashedFile = struct {
     path: []const u8,
-    hash: [Hash.digest_length]u8,
+    hash: [Manifest.Hash.digest_length]u8,
     failure: Error!void,
 
     const Error = fs.File.OpenError || fs.File.ReadError || fs.File.StatError;
@@ -507,7 +496,7 @@ const HashedFile = struct {
 fn computePackageHash(
     thread_pool: *ThreadPool,
     pkg_dir: fs.IterableDir,
-) ![Hash.digest_length]u8 {
+) ![Manifest.Hash.digest_length]u8 {
     const gpa = thread_pool.allocator;
 
     // We'll use an arena allocator for the path name strings since they all
@@ -550,7 +539,7 @@ fn computePackageHash(
 
     std.sort.sort(*HashedFile, all_files.items, {}, HashedFile.lessThan);
 
-    var hasher = Hash.init(.{});
+    var hasher = Manifest.Hash.init(.{});
     var any_failures = false;
     for (all_files.items) |hashed_file| {
         hashed_file.failure catch |err| {
@@ -571,7 +560,7 @@ fn workerHashFile(dir: fs.Dir, hashed_file: *HashedFile, wg: *WaitGroup) void {
 fn hashFileFallible(dir: fs.Dir, hashed_file: *HashedFile) HashedFile.Error!void {
     var buf: [8000]u8 = undefined;
     var file = try dir.openFile(hashed_file.path, .{});
-    var hasher = Hash.init(.{});
+    var hasher = Manifest.Hash.init(.{});
     hasher.update(hashed_file.path);
     hasher.update(&.{ 0, @boolToInt(try isExecutable(file)) });
     while (true) {
@@ -595,52 +584,6 @@ fn isExecutable(file: fs.File) !bool {
     }
 }
 
-const hex_charset = "0123456789abcdef";
-
-fn hex64(x: u64) [16]u8 {
-    var result: [16]u8 = undefined;
-    var i: usize = 0;
-    while (i < 8) : (i += 1) {
-        const byte = @truncate(u8, x >> @intCast(u6, 8 * i));
-        result[i * 2 + 0] = hex_charset[byte >> 4];
-        result[i * 2 + 1] = hex_charset[byte & 15];
-    }
-    return result;
-}
-
-test hex64 {
-    const s = "[" ++ hex64(0x12345678_abcdef00) ++ "]";
-    try std.testing.expectEqualStrings("[00efcdab78563412]", s);
-}
-
-const multihash_function: MultihashFunction = switch (Hash) {
-    std.crypto.hash.sha2.Sha256 => .@"sha2-256",
-    else => @compileError("unreachable"),
-};
-comptime {
-    // We avoid unnecessary uleb128 code in hexDigest by asserting here the
-    // values are small enough to be contained in the one-byte encoding.
-    assert(@enumToInt(multihash_function) < 127);
-    assert(Hash.digest_length < 127);
-}
-const multihash_len = 1 + 1 + Hash.digest_length;
-
-fn hexDigest(digest: [Hash.digest_length]u8) [multihash_len * 2]u8 {
-    var result: [multihash_len * 2]u8 = undefined;
-
-    result[0] = hex_charset[@enumToInt(multihash_function) >> 4];
-    result[1] = hex_charset[@enumToInt(multihash_function) & 15];
-
-    result[2] = hex_charset[Hash.digest_length >> 4];
-    result[3] = hex_charset[Hash.digest_length & 15];
-
-    for (digest) |byte, i| {
-        result[4 + i * 2] = hex_charset[byte >> 4];
-        result[5 + i * 2] = hex_charset[byte & 15];
-    }
-    return result;
-}
-
 fn renameTmpIntoCache(
     cache_dir: fs.Dir,
     tmp_dir_sub_path: []const u8,
@@ -669,21 +612,3 @@ fn renameTmpIntoCache(
         break;
     }
 }
-
-const MultihashFunction = enum(u16) {
-    identity = 0x00,
-    sha1 = 0x11,
-    @"sha2-256" = 0x12,
-    @"sha2-512" = 0x13,
-    @"sha3-512" = 0x14,
-    @"sha3-384" = 0x15,
-    @"sha3-256" = 0x16,
-    @"sha3-224" = 0x17,
-    @"sha2-384" = 0x20,
-    @"sha2-256-trunc254-padded" = 0x1012,
-    @"sha2-224" = 0x1013,
-    @"sha2-512-224" = 0x1014,
-    @"sha2-512-256" = 0x1015,
-    @"blake2b-256" = 0xb220,
-    _,
-};

src/main.zig

@@ -3915,6 +3915,7 @@ pub const usage_build =
 ;
 
 pub fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
+    var color: Color = .auto;
     var prominent_compile_errors: bool = false;
 
     // We want to release all the locks before executing the child process, so we make a nice
@@ -4117,6 +4118,7 @@ pub fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !voi
             // Here we borrow main package's table and will replace it with a fresh
             // one after this process completes.
             main_pkg.fetchAndAddDependencies(
+                arena,
                 &thread_pool,
                 &http_client,
                 build_directory,
@@ -4125,6 +4127,7 @@ pub fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !voi
                 &dependencies_source,
                 &build_roots_source,
                 "",
+                color,
             ) catch |err| switch (err) {
                 error.PackageFetchFailed => process.exit(1),
                 else => |e| return e,
@@ -4361,12 +4364,12 @@ pub fn cmdFmt(gpa: Allocator, arena: Allocator, args: []const []const u8) !void
         };
         defer gpa.free(source_code);
 
-        var tree = std.zig.parse(gpa, source_code) catch |err| {
+        var tree = Ast.parse(gpa, source_code, .zig) catch |err| {
             fatal("error parsing stdin: {}", .{err});
         };
         defer tree.deinit(gpa);
 
-        try printErrsMsgToStdErr(gpa, arena, tree.errors, tree, "<stdin>", color);
+        try printErrsMsgToStdErr(gpa, arena, tree, "<stdin>", color);
         var has_ast_error = false;
         if (check_ast_flag) {
             const Module = @import("Module.zig");
@@ -4566,10 +4569,10 @@ fn fmtPathFile(
     // Add to set after no longer possible to get error.IsDir.
     if (try fmt.seen.fetchPut(stat.inode, {})) |_| return;
 
-    var tree = try std.zig.parse(fmt.gpa, source_code);
+    var tree = try Ast.parse(fmt.gpa, source_code, .zig);
     defer tree.deinit(fmt.gpa);
 
-    try printErrsMsgToStdErr(fmt.gpa, fmt.arena, tree.errors, tree, file_path, fmt.color);
+    try printErrsMsgToStdErr(fmt.gpa, fmt.arena, tree, file_path, fmt.color);
     if (tree.errors.len != 0) {
         fmt.any_error = true;
         return;
@@ -4649,14 +4652,14 @@ fn fmtPathFile(
     }
 }
 
-fn printErrsMsgToStdErr(
+pub fn printErrsMsgToStdErr(
     gpa: mem.Allocator,
     arena: mem.Allocator,
-    parse_errors: []const Ast.Error,
     tree: Ast,
     path: []const u8,
     color: Color,
 ) !void {
+    const parse_errors: []const Ast.Error = tree.errors;
     var i: usize = 0;
     while (i < parse_errors.len) : (i += 1) {
         const parse_error = parse_errors[i];
@@ -5312,11 +5315,11 @@ pub fn cmdAstCheck(
     file.pkg = try Package.create(gpa, "root", null, file.sub_file_path);
     defer file.pkg.destroy(gpa);
 
-    file.tree = try std.zig.parse(gpa, file.source);
+    file.tree = try Ast.parse(gpa, file.source, .zig);
     file.tree_loaded = true;
     defer file.tree.deinit(gpa);
 
-    try printErrsMsgToStdErr(gpa, arena, file.tree.errors, file.tree, file.sub_file_path, color);
+    try printErrsMsgToStdErr(gpa, arena, file.tree, file.sub_file_path, color);
     if (file.tree.errors.len != 0) {
         process.exit(1);
     }
@@ -5438,11 +5441,11 @@ pub fn cmdChangelist(
     file.source = source;
     file.source_loaded = true;
 
-    file.tree = try std.zig.parse(gpa, file.source);
+    file.tree = try Ast.parse(gpa, file.source, .zig);
     file.tree_loaded = true;
     defer file.tree.deinit(gpa);
 
-    try printErrsMsgToStdErr(gpa, arena, file.tree.errors, file.tree, old_source_file, .auto);
+    try printErrsMsgToStdErr(gpa, arena, file.tree, old_source_file, .auto);
     if (file.tree.errors.len != 0) {
         process.exit(1);
     }
@@ -5476,10 +5479,10 @@ pub fn cmdChangelist(
     if (new_amt != new_stat.size)
         return error.UnexpectedEndOfFile;
 
-    var new_tree = try std.zig.parse(gpa, new_source);
+    var new_tree = try Ast.parse(gpa, new_source, .zig);
     defer new_tree.deinit(gpa);
 
-    try printErrsMsgToStdErr(gpa, arena, new_tree.errors, new_tree, new_source_file, .auto);
+    try printErrsMsgToStdErr(gpa, arena, new_tree, new_source_file, .auto);
     if (new_tree.errors.len != 0) {
         process.exit(1);
     }