[clang] [Clang][Sema] Allow counted_by on void* as GNU extension (PR #164737)

[Kees Cook via cfe-commits]

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@@ -272,6 +286,11 @@ GetCountedByAttrOnIncompletePointee(QualType Ty, NamedDecl **ND) {
   if (!PointeeTy->isIncompleteType(ND))
     return {};
 
+  // If counted_by is on void*, it was already validated at declaration time
+  // as a GNU extension. No need to re-check GNU mode here.
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kees wrote:

Ah yes, this isn't a useful comment any more. I will drop this.

https://github.com/llvm/llvm-project/pull/164737