ayzhao added inline comments.
================
Comment at: clang/lib/Sema/SemaInit.cpp:4151
+ QualType T = Entity.getType();
+ // FIXME: Union is unsupported.
+ int InitKind = T->isArrayType() ? 0 : 4;
----------------
ayzhao wrote:
> Hmm...it seems like as is this patch generates the correct code for
> parentheses-initialized `union`s:
>
> ```
> % cat ~/src/tests/test-union.cc
> union C {
> float a;
> double b;
> };
>
>
> C foo() {
> return C(1);
> }
>
> % bin/clang++ -std=c++20 -emit-llvm -S -c -o - ~/src/tests/test-union.cc
> ; ModuleID = '/usr/local/google/home/ayzhao/src/tests/test-union.cc'
> source_filename = "/usr/local/google/home/ayzhao/src/tests/test-union.cc"
> target datalayout =
> "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
> target triple = "x86_64-unknown-linux-gnu"
>
> %union.C = type { double }
>
> ; Function Attrs: mustprogress noinline nounwind optnone uwtable
> define dso_local double @_Z3foov() #0 {
> entry:
> %retval = alloca %union.C, align 8
> store float 1.000000e+00, ptr %retval, align 8
> %coerce.dive = getelementptr inbounds %union.C, ptr %retval, i32 0, i32 0
> %0 = load double, ptr %coerce.dive, align 8
> ret double %0
> }
>
> attributes #0 = { mustprogress noinline nounwind optnone uwtable
> "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true"
> "stack-protector-buffer-size"="8" "target-cpu"="x86-64"
> "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
>
> !llvm.linker.options = !{}
> !llvm.module.flags = !{!0, !1, !2, !3, !4}
> !llvm.ident = !{!5}
>
> !0 = !{i32 1, !"wchar_size", i32 4}
> !1 = !{i32 8, !"PIC Level", i32 2}
> !2 = !{i32 7, !"PIE Level", i32 2}
> !3 = !{i32 7, !"uwtable", i32 2}
> !4 = !{i32 7, !"frame-pointer", i32 2}
> !5 = !{!"clang version 16.0.0"}
> ```
>
> I'm guessing this comment is specific to error messages.
OK, I see what's going on. The following program fails to build:
```
#include <string>
union C {
int a;
std::string b;
};
C foo() {
return C("Hello, World!");
}
```
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D129531/new/
https://reviews.llvm.org/D129531
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
