[clang] [coroutines] Introduce [[clang::coro_return_type]] and [[clang::coro_wrapper]] (PR #71945)

[Haojian Wu via cfe-commits]

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@@ -15811,6 +15813,32 @@ static void diagnoseImplicitlyRetainedSelf(Sema &S) {
           << FixItHint::CreateInsertion(P.first, "self->");
 }
 
+// Return whether FD is `promise_type::get_return_object`.
+bool isGetReturnObject(FunctionDecl *FD) {
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hokein wrote:

nit: this function is only used in this TU, add `static`

https://github.com/llvm/llvm-project/pull/71945