[clang] [Clang][Sema] Diagnosis for constexpr constructor not initializing a union member (PR #81042)

[via cfe-commits]

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@@ -224,6 +224,9 @@ struct TemplateInit {
   };
   // FIXME: This is ill-formed (no diagnostic required). We should diagnose it.
   constexpr TemplateInit() {} // desired-error {{must initialize all members}}
+#ifndef CXX2A
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mahtohappy wrote:

yes, I'm here just following the convention in that file and didn't want to change the run command
https://github.com/llvm/llvm-project/blob/main/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp

https://github.com/llvm/llvm-project/pull/81042