From aea6096daa761b0cc1cdd8772bbe3987c32b238b Mon Sep 17 00:00:00 2001
From: Yuxuan Chen <ych@meta.com>
Date: Fri, 3 Jan 2025 10:40:29 -0800
Subject: [PATCH] add `[[clang::coro_await_elidable]]` to `NothrowAwaitable`
 and `TryAwaitable`

Summary: [[clang::coro_await_elidable]] is an attribute to help us elide more coroutine heap allocations. See the diff where we enabled it. D58956574

Reviewed By: skrueger

Differential Revision: D67299322

fbshipit-source-id: 2321765fd8818d8025e4e5c4a2f83a52544c1b37
---
 folly/coro/ViaIfAsync.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/folly/coro/ViaIfAsync.h b/folly/coro/ViaIfAsync.h
index e4f96d56759..11e98d7e8ee 100644
--- a/folly/coro/ViaIfAsync.h
+++ b/folly/coro/ViaIfAsync.h
@@ -645,7 +645,8 @@ class CommutativeWrapperAwaitable {
 };
 
 template <typename T>
-class TryAwaitable : public CommutativeWrapperAwaitable<TryAwaitable, T> {
+class [[FOLLY_ATTR_CLANG_CORO_AWAIT_ELIDABLE]] TryAwaitable
+    : public CommutativeWrapperAwaitable<TryAwaitable, T> {
  public:
   using CommutativeWrapperAwaitable<TryAwaitable, T>::
       CommutativeWrapperAwaitable;
@@ -680,7 +681,7 @@ using semi_await_try_result_t =
 namespace detail {
 
 template <typename T>
-class NothrowAwaitable
+class [[FOLLY_ATTR_CLANG_CORO_AWAIT_ELIDABLE]] NothrowAwaitable
     : public CommutativeWrapperAwaitable<NothrowAwaitable, T> {
  public:
   using CommutativeWrapperAwaitable<NothrowAwaitable, T>::