[clang] [Clang] Added clang diagnostic when snprintf/vsnprintf uses sizeof(de… (PR #170637)

[Oliver Hunt via cfe-commits]

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@@ -1451,6 +1451,8 @@ void Sema::checkFortifiedBuiltinMemoryFunction(FunctionDecl *FD,
     DestinationSize = ComputeSizeArgument(0);
     const Expr *LenArg = TheCall->getArg(1)->IgnoreParenImpCasts();
     const Expr *Dest = TheCall->getArg(0)->IgnoreParenImpCasts();
+    if (const auto *DestCast = dyn_cast_or_null<CastExpr>(Dest))
+      Dest = DestCast->getSubExprAsWritten();
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ojhunt wrote:

Why as written rather than just `getSubExpr()`?

https://github.com/llvm/llvm-project/pull/170637