[clang] Sema: detect adjusted function prototypes to fix crash with __typeof + __asm + noreturn (#173598) (PR #174092)

[Shafik Yaghmour via cfe-commits]

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@@ -9529,12 +9529,23 @@ static FunctionDecl *CreateNewFunctionDecl(Sema &SemaRef, Declarator &D,
     //     declarator to still have a function type. e.g.,
     //       typedef void func(int a);
     //       __attribute__((noreturn)) func other_func; // This has a prototype
+    auto HasFunctionPrototype = [&](QualType T) -> bool {
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shafik wrote:

This does not looks like a good simplification to me. I either would not have bothered and just added the `isNull()` check below or I would have created a lambda that takes `D` and `R` from below by reference and did the whole set of checks and assigned that result to `HasPrototype`.

https://github.com/llvm/llvm-project/pull/174092