[clang] [clang] Report Diagnostic when builtin vector has negative size (PR #166055)

[Aaron Ballman via cfe-commits]

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@@ -8306,6 +8316,14 @@ static void HandleExtVectorTypeAttr(QualType &CurType, const ParsedAttr &Attr,
   QualType T = S.BuildExtVectorType(CurType, SizeExpr, Attr.getLoc());
   if (!T.isNull())
     CurType = T;
+
+  std::optional<llvm::APSInt> VecSize =
+      SizeExpr->getIntegerConstantExpr(S.Context);
+  if (VecSize && VecSize->isNegative()) {
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AaronBallman wrote:

Similar, I think this should live in `BuildExtVectorType()`.

https://github.com/llvm/llvm-project/pull/166055