From a25f94ddb26d218af2ecbf7cdf943ac755a355a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adri=C3=A0=20Arrufat?= <adria.arrufat@gmail.com>
Date: Wed, 11 Mar 2026 22:17:26 +0900
Subject: [PATCH] Sema: handle generic poison in rounding builtins

---
 src/Sema.zig           | 42 +++++++++++++++++++++++++-----------------
 test/behavior/cast.zig | 17 +++++++++++++++++
 2 files changed, 42 insertions(+), 17 deletions(-)

diff --git a/src/Sema.zig b/src/Sema.zig
index 90a9533171..8bce6432ee 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -20850,30 +20850,36 @@ fn zirRoundCast(
     const src = block.nodeOffset(extra.node);
     const operand_src = block.builtinCallArgSrc(extra.node, 0);
 
-    const builtin_name = switch (mode) {
-        .round => "@round",
-        .floor => "@floor",
-        .ceil => "@ceil",
-        .truncate => "@trunc",
-        .exact => unreachable,
-    };
+    const dest_ty_or_poison = try sema.resolveTypeOrPoison(block, src, extra.lhs) orelse Type.generic_poison;
+    var dest_ty = dest_ty_or_poison;
+    if (!dest_ty.isGenericPoison()) {
+        if (dest_ty.zigTypeTag(zcu) == .error_union) {
+            dest_ty = dest_ty.errorUnionPayload(zcu);
+        }
+        if (dest_ty.zigTypeTag(zcu) == .optional) {
+            dest_ty = dest_ty.childType(zcu);
+        }
+    }
 
-    const dest_ty = try sema.resolveDestType(block, src, extra.lhs, .remove_eu_opt, builtin_name);
     const operand = sema.resolveInst(extra.rhs);
     const operand_ty = sema.typeOf(operand);
 
-    try sema.checkVectorizableBinaryOperands(block, operand_src, dest_ty, operand_ty, src, operand_src);
-    const dest_scalar_ty = dest_ty.scalarType(zcu);
+    const is_poison = dest_ty.isGenericPoison();
+    if (!is_poison) {
+        try sema.checkVectorizableBinaryOperands(block, operand_src, dest_ty, operand_ty, src, operand_src);
+    }
+    const dest_scalar_ty = if (is_poison) dest_ty else dest_ty.scalarType(zcu);
     const operand_scalar_ty = operand_ty.scalarType(zcu);
 
-    if (dest_scalar_ty.zigTypeTag(zcu) == .float or dest_scalar_ty.zigTypeTag(zcu) == .comptime_float) {
+    if (is_poison or dest_scalar_ty.zigTypeTag(zcu) == .float or dest_scalar_ty.zigTypeTag(zcu) == .comptime_float) {
         const coerced_operand = try sema.coerce(block, dest_ty, operand, operand_src);
+        const math_ty = if (is_poison) operand_ty else dest_ty;
 
         const result_ref = switch (mode) {
-            .round => try sema.maybeConstantUnaryMath(coerced_operand, dest_ty, Value.round),
-            .floor => try sema.maybeConstantUnaryMath(coerced_operand, dest_ty, Value.floor),
-            .ceil => try sema.maybeConstantUnaryMath(coerced_operand, dest_ty, Value.ceil),
-            .truncate => try sema.maybeConstantUnaryMath(coerced_operand, dest_ty, Value.trunc),
+            .round => try sema.maybeConstantUnaryMath(coerced_operand, math_ty, Value.round),
+            .floor => try sema.maybeConstantUnaryMath(coerced_operand, math_ty, Value.floor),
+            .ceil => try sema.maybeConstantUnaryMath(coerced_operand, math_ty, Value.ceil),
+            .truncate => try sema.maybeConstantUnaryMath(coerced_operand, math_ty, Value.trunc),
             else => unreachable,
         };
 
@@ -25122,9 +25128,11 @@ fn zirRoundOpType(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstDa
     const extra = sema.code.extraData(Zir.Inst.UnNode, extended.operand).data;
     const operand_src = block.builtinCallArgSrc(extra.node, 0);
 
-    const dest_ty = try sema.resolveDestType(block, operand_src, extra.operand, .remove_eu_opt, "type hint");
+    const dest_ty_or_poison = try sema.resolveTypeOrPoison(block, operand_src, extra.operand) orelse Type.generic_poison;
 
-    const float_ty = dest_ty.optEuBaseType(zcu);
+    if (dest_ty_or_poison.isGenericPoison()) return .generic_poison_type;
+
+    const float_ty = dest_ty_or_poison.optEuBaseType(zcu);
     switch (float_ty.scalarType(zcu).zigTypeTag(zcu)) {
         .float, .comptime_float => return .fromType(float_ty),
         else => return .comptime_float_type,
diff --git a/test/behavior/cast.zig b/test/behavior/cast.zig
index da54201ab8..04c5ce3848 100644
--- a/test/behavior/cast.zig
+++ b/test/behavior/cast.zig
@@ -253,6 +253,23 @@ fn testIntFromFloats() !void {
     try expectTruncCast(f32, -128.2, i8, -128);
 }
 
+test "rounding builtins with anytype and context propagation" {
+    const S = struct {
+        const x: i32 = 10;
+        fn check(expected: anytype, actual: anytype) !void {
+            try expectEqual(expected, actual);
+        }
+    };
+    try expectEqual(@as(f32, 1.0), @round(@as(f32, 1.4)));
+    try S.check(@as(f32, 1.0), @round(@as(f32, 1.4)));
+
+    const y: f64 = @floor(@floatFromInt(S.x));
+    try expect(y == 10.0);
+
+    try expectEqual(1.0, @round(1.4));
+    try S.check(1.0, @round(1.4));
+}
+
 fn expectIntFromFloat(comptime F: type, f: F, comptime I: type, i: I) !void {
     try expect(@as(I, @intFromFloat(f)) == i);
 }