std.Io: add ResetEvent based on futexes

and add futex to the vtable. A future commit may make the other sync
primitives based on futexes.

lib/std/Io/File/Writer.zig

@@ -52,14 +52,14 @@ pub const Mode = union(enum) {
         return switch (m) {
             .positional, .positional_simple => .positional_simple,
             .streaming, .streaming_simple => .streaming_simple,
-            inline else => |x| x,
+            inline else => |_, x| x,
         };
     }
 
     pub fn toUnescaped(m: @This()) @This() {
         return switch (m) {
             .terminal_escaped => .streaming_simple,
-            inline else => |x| x,
+            inline else => |_, x| x,
         };
     }
 
@@ -469,13 +469,13 @@ pub fn restoreEscape(w: *Writer, mode: Mode) void {
     w.mode = mode;
 }
 
-pub fn writeAllUnescaped(w: *Writer, bytes: []const u8) Io.Error!void {
+pub fn writeAllUnescaped(w: *Writer, bytes: []const u8) Io.Writer.Error!void {
     const prev_mode = w.disableEscape();
     defer w.restoreEscape(prev_mode);
     return w.interface.writeAll(bytes);
 }
 
-pub fn printUnescaped(w: *Writer, comptime fmt: []const u8, args: anytype) Io.Error!void {
+pub fn printUnescaped(w: *Writer, comptime fmt: []const u8, args: anytype) Io.Writer.Error!void {
     const prev_mode = w.disableEscape();
     defer w.restoreEscape(prev_mode);
     return w.interface.print(fmt, args);

lib/std/Progress.zig

@@ -52,6 +52,8 @@ node_freelist: Freelist,
 /// value may at times temporarily exceed the node count.
 node_end_index: u32,
 
+start_failure: StartFailure,
+
 pub const Status = enum {
     /// Indicates the application is progressing towards completion of a task.
     /// Unless the application is interactive, this is the only status the
@@ -448,6 +450,8 @@ const noop_impl = builtin.single_threaded or switch (builtin.os.tag) {
 /// Asserts there is only one global Progress instance.
 ///
 /// Call `Node.end` when done.
+///
+/// If an error occurs, `start_failure` will be populated.
 pub fn start(options: Options, io: Io) Node {
     // Ensure there is only 1 global Progress object.
     if (global_progress.node_end_index != 0) {
@@ -757,7 +761,7 @@ fn appendTreeSymbol(symbol: TreeSymbol, buf: []u8, start_i: usize) usize {
 
 pub fn clearWrittenWithEscapeCodes(file_writer: *Io.File.Writer) anyerror!void {
     if (noop_impl or !global_progress.need_clear) return;
-    try file_writer.interface.writeAllUnescaped(clear ++ progress_remove);
+    try file_writer.writeAllUnescaped(clear ++ progress_remove);
     global_progress.need_clear = false;
 }