[clang] [-Wunsafe-buffer-usage] Allow strerror for %s in printf-like calls (PR #175208)

[Oliver Hunt via cfe-commits]

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@@ -771,6 +771,11 @@ static bool isNullTermPointer(const Expr *Ptr, ASTContext &Ctx) {
       if (MD->getName() == "c_str" && RD->getName() == "basic_string")
         return true;
   }
+  if (auto *CE = dyn_cast<CallExpr>(Ptr->IgnoreParenImpCasts())) {
+    const FunctionDecl *F = CE->getDirectCallee();
+    if (F && F->getIdentifier() && F->getName() == "strerror")
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ojhunt wrote:

I think we should have an array of known function names or better yet some way to annotate functions/return types - I believe that the -fbounds-safety work includes such an attribute, but using that attribute would seem to depend on having bounds safety enabled, which I think is a stricter requirement than we want for this.

https://github.com/llvm/llvm-project/pull/175208