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

[Yuxuan Chen 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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yuxuanchen1997 wrote:

> So after this patch, we could actually check await_transform and also operator co_await and thereby get rid of the CurFnAwaitElidable check?

No, not yet. I am just saying that we can potentially check the entire expression built here including the `CallerType::await_transform` and `CalleeType::operator co_await` part. Right now we are just checking the immediate operand before any transformation customization points. 

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