perf(channel): reduce send coroutine frame storage

CHANGELOG.md

@@ -61,6 +61,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- **Smaller channel send coroutine frames**: `channel<T>::send(...)` now lets
+  its internal waiter borrow the by-value payload already owned by the send
+  coroutine frame instead of retaining a second moved-from/moved-to `T` pair.
+  Directly constructed public send awaiters remain owning, and queue,
+  cancellation, close, and dequeue-versus-destruction behavior is unchanged
+  (#1047).
 - **Allocation-free ready semaphore acquires**: Non-cancellable acquires now
   defer shared wake-state allocation until the ready permit check fails.
   Entering `await_suspend` allocates before taking the semaphore queue lock,

examples/CMakeLists.txt

@@ -66,6 +66,13 @@ add_executable(bench_channel bench_channel.cpp)
 target_link_libraries(bench_channel PRIVATE elio)
 target_link_options(bench_channel PRIVATE ${STATIC_LINK_FLAGS})
 
+add_executable(bench_channel_send_frame
+    bench_channel_send_frame.cpp
+    channel_send_frame_bench_factory.cpp
+)
+target_link_libraries(bench_channel_send_frame PRIVATE elio)
+target_link_options(bench_channel_send_frame PRIVATE ${STATIC_LINK_FLAGS})
+
 # Signal handling example
 add_executable(signal_handling signal_handling.cpp)
 target_link_libraries(signal_handling PRIVATE elio)