Commit f782202910

@@ -22368,7 +22368,10 @@ fn zirErrorCast(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstData
 
     try sema.requireRuntimeBlock(block, src, operand_src);
     const err_int_ty = try mod.errorIntType();
-    if (block.wantSafety() and !dest_ty.isAnyError(mod) and sema.mod.backendSupportsFeature(.error_set_has_value)) {
+    if (block.wantSafety() and !dest_ty.isAnyError(mod) and
+        dest_ty.toIntern() != .adhoc_inferred_error_set_type and
+        sema.mod.backendSupportsFeature(.error_set_has_value))
+    {
         if (dest_tag == .ErrorUnion) {
             const err_code = try sema.analyzeErrUnionCode(block, operand_src, operand);
             const err_int = try block.addBitCast(err_int_ty, err_code);

@@ -1027,3 +1027,15 @@ test "generic type constructed from inferred error set of unresolved function" {
     };
     _ = std.io.multiWriter(.{S.writer()});
 }
+
+test "errorCast to adhoc inferred error set" {
+    const S = struct {
+        inline fn baz() !i32 {
+            return @errorCast(err());
+        }
+        fn err() anyerror!i32 {
+            return 1234;
+        }
+    };
+    try std.testing.expect((try S.baz()) == 1234);
+}