[clang] [Clang] Propagate elide safe context through [[clang::coro_must_await]] (PR #108474)

[Adrian Vogelsgesang via cfe-commits]

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@@ -880,14 +898,12 @@ ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *Operand,
   }
 
   auto *RD = Promise->getType()->getAsCXXRecordDecl();
-  bool AwaitElidable =
-      isCoroAwaitElidableCall(Operand) &&
-      isAttributedCoroAwaitElidable(
-          getCurFunctionDecl(/*AllowLambda=*/true)->getReturnType());
-
-  if (AwaitElidable)
-    if (auto *Call = dyn_cast<CallExpr>(Operand->IgnoreImplicit()))
-      Call->setCoroElideSafe();
+
+  bool CurFnAwaitElidable = isAttributedCoroAwaitElidable(
+      getCurFunctionDecl(/*AllowLambda=*/true)->getReturnType());
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vogelsgesang wrote:

shouldn't we actually check if the return type of àwait_transform` is marked as elideable, instead of the immediate argument to `co_await`? Or maybe we should check that both the immediate argument and the transformed awaitable are annotated?

(Not really related to this commit. I just noticed this as I was reviewing this code change here. Fell free to ship this PR without addressing this comment. In case this is actually something we want to change, we should probably do so in a separate PR, anyway...)

https://github.com/llvm/llvm-project/pull/108474