[PATCH] D129531: [clang][C++20] P0960R3: Allow initializing aggregates from a parenthesized list of values

[Alan Zhao via Phabricator via cfe-commits]

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;
----------------
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.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129531/new/

https://reviews.llvm.org/D129531