[clang] [LifeitimeSafety] Support C Language in LifetimeSafety (PR #203270)

[Gábor Horváth via cfe-commits]

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@@ -347,6 +353,12 @@ void FactsGenerator::VisitUnaryOperator(const UnaryOperator *UO) {
   switch (UO->getOpcode()) {
   case UO_AddrOf: {
     const Expr *SubExpr = UO->getSubExpr();
+    // In C, function addresses do not need lifetime tracking. Also skip
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Xazax-hun wrote:

There are two cases I can think of, you either take the address of a lambda, in that case you have the address of an object (wherever that lambda is stored, usually on the stack). That is not a function pointer. Or you could take the address of the `operator()(...)` of the lambda, but that is going to have static lifetime.

There is a 3rd case, lambdas can implicitly be converted to function pointers, but only if they do not capture anything. No `&` is involved there and the returned pointer should have static lifetime.

That being said if you have a code snippet in mind feel free to share it, just in case I am missing something. 

https://github.com/llvm/llvm-project/pull/203270