[clang] [Clang][Interp] Diagnose use sizeless vector type as the argument of `__builtin_vectorelements` (PR #99794)

[Timm Baeder via cfe-commits]

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@@ -2735,6 +2736,13 @@ inline bool InvalidDeclRef(InterpState &S, CodePtr OpPC,
   return CheckDeclRef(S, OpPC, DR);
 }
 
+inline bool SizelessVectorElementSize(InterpState &S, CodePtr OpPC) {
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tbaederr wrote:

If you look at what the current interpreter does: 1) This should use `CCEDiag` instead and 2) the diagnostic should only be emitted if we're in a constant context

https://github.com/llvm/llvm-project/pull/99794