[clang] [-Wunsafe-buffer-usage] Fix a bug and suppress libc warnings for C files (PR #109496)

[Henrik G. Olsson via cfe-commits]

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@@ -789,7 +791,7 @@ AST_MATCHER_P(CallExpr, hasUnsafePrintfStringArg,
   if (!FristParmTy->isPointerType())
     return false; // possibly some user-defined printf function
 
-  QualType FirstPteTy = (cast<PointerType>(FristParmTy))->getPointeeType();
+  QualType FirstPteTy = FristParmTy->getAs<PointerType>()->getPointeeType();
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hnrklssn wrote:

Nit: FristParmTy -> FirstParmTy

https://github.com/llvm/llvm-project/pull/109496