ev-stdexec-copy-elision-member-awaitable-002¶
| 字段 | 值 |
|---|---|
| 项目 | NVIDIA/stdexec |
| 固定 commit | 6d7ad689f4d4 |
| 路径 | include/stdexec/__detail/__connect_awaitable.hpp |
| 行段 | L169-L176 |
| 特性 | 保证的复制消除 |
| 许可证 | Apache-2.0 |
| 代码来源 | 项目源码 |
| 级别 | manual |
| 审核 | zyuhao7 @ 2026-10-27 |
| 测试代码 | 否 |
| 发现方式 | manual |
用法¶
注释说明成员以函数返回值直接初始化本应触发强制复制消除，GCC 未实现时退回手动生命周期管理
为什么典型¶
把规则用在成员初始化上；同时展示编译器缺陷迫使库作者准备回退路径。
摘录¶
// GCC doesn't like initializing __awaitable_ or __awaiter_ in the member initializer
// clause when the result of __get_awaitable or __get_awaiter is immovable; it *seems*
// like direct initialization of a member with the result of a function ought to trigger
// C++17's mandatory copy elision, and both Clang and MSVC accept that code, but using
// __manual_lifetime works around the issue.
__awaitable_.__construct_from(__get_awaitable,
static_cast<_Awaitable&&>(__source),
__coro.promise());
备注¶
生产路径；协程 awaitable 包装的构造逻辑，用 __manual_lifetime 绕过 GCC 的复制消除缺陷。