[clang] [coroutines][coro_lifetimebound] Detect lifetime issues with lambda captures (PR #77066)

[Utkarsh Saxena via cfe-commits]

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@@ -15845,8 +15845,10 @@ void Sema::CheckCoroutineWrapper(FunctionDecl *FD) {
   RecordDecl *RD = FD->getReturnType()->getAsRecordDecl();
   if (!RD || !RD->getUnderlyingDecl()->hasAttr<CoroReturnTypeAttr>())
     return;
-  // Allow `get_return_object()`.
-  if (FD->getDeclName().isIdentifier() &&
+  // Allow some_promise_type::get_return_object().
+  // Since we are still in the promise definition, we can only do this
+  // heuristically as the promise may not be yet associated to a coroutine.
+  if (isa<CXXMethodDecl>(FD) && FD->getDeclName().isIdentifier() &&
       FD->getName().equals("get_return_object") && FD->param_empty())
     return;
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usx95 wrote:

> But in that case we shouldn't see any coro_return_type annotations either and there will be no pending actions? I don't see why this approach won't work.

Why not ? We would always see the `coro_return_type` annotation for the return type. The declaration (and therefore the annotations) of `CoroReturnType` would be visible to `CoroReturnType get_return_object() { return {}; }`. This TU does not have to have a coroutine definition. 

https://github.com/llvm/llvm-project/pull/77066