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

[Aaron Ballman via cfe-commits]

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@@ -8285,10 +8285,20 @@ static void HandleVectorSizeAttr(QualType &CurType, const ParsedAttr &Attr,
 
   Expr *SizeExpr = Attr.getArgAsExpr(0);
   QualType T = S.BuildVectorType(CurType, SizeExpr, Attr.getLoc());
-  if (!T.isNull())
-    CurType = T;
-  else
+  if (T.isNull()) {
+    Attr.setInvalid();
+    return;
+  }
+
+  std::optional<llvm::APSInt> VecSize =
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AaronBallman wrote:

I think this logic should live in `BuildVectorType()` instead, near where we emit `err_attribute_invalid_size`.

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