================
@@ -9363,6 +9363,119 @@ Example:
}];
}
+def CoroAwaitSuspendDestroyDoc : Documentation {
+ let Category = DocCatFunction;
+ let Content = [{
+
+The ``[[clang::coro_await_suspend_destroy]]`` attribute applies to an
+``await_suspend(std::coroutine_handle<Promise>)`` member function of a
+coroutine awaiter. When applied, suspensions into the awaiter use an optimized
+call path that bypasses standard suspend intrinsics, and immediately destroys
+the suspending coro.
+
+Each annotated ``await_suspend`` member must contain a compatibility stub:
+
+.. code-block:: c++
+
+ [[clang::coro_await_suspend_destroy]]
+ void await_suspend(std::coroutine_handle<Promise> handle) {
+ await_suspend_destroy(handle.promise());
+ handle.destroy();
+ }
----------------
snarkmaster wrote:
Here is what is **the same** in both the old and the new version:
- The compiler does not constrain the implementation of `await_suspend()`.
- Normal users SHOULD implement a portability `await_suspend()` with those
two lines -- it should be very uncommon not to do this.
- Given the attribute, the emitted code only uses `await_suspend_destroy()`
-- the stub does not run.
The only thing that **differs** is that in the new version, we test-call
`await_suspend()` to check for the attribute, so as a result:
- `await_suspend()` must be at least declared, and have the same return type
as `await_suspend_destroy()`
IMO, having to declare both functions is a good tradeoff in exchange for the
outcome is that an awaiter can use overloads to select whether or not it is
short-circuiting in a particular promise.
If you need me to elaborate **why** it's useful to have the overload selection,
I can write more.
---
As far as the comment, I will make the requirements more explicit in the doc,
and replace "must" by "should".
https://github.com/llvm/llvm-project/pull/152623
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