co_composed produces mismatched new/delete

[justend29]

Forward: asio is a gift to humanity.

Issue

GCC's -Wmismatched-new-delete warns on usages of co_composed. Although this may be spurious, it could indicate an intrinsic issue. The warnings can be reproduced with asio's native tests of co_composed.

Reproduction

I'm not sure how to compile & run individual tests in asio, but the tests of concern are those in asio/src/tests/unit/experimental/co_composed.cpp. Reproducing these warnings was accomplished with GCC 13.2.1 through:

git clone https://github.com/chriskohlhoff/asio.git
cd asio/asio
./autogen.sh
./configure CXXFLAGS='-std=c++20 -Wmismatche-new-delete'
make check

Sample Warning

unit/experimental/co_composed.cpp: In lambda function:
unit/experimental/co_composed.cpp:169:9: warning: ‘static void asio::experimental::detail::co_composed_promise<Execu
tors, Handler, Return>::operator delete(void*, std::size_t) [with Executors = void(asio::io_context::basic_executor_type<std::allocator<void>, 0>); Handler = asio::experimental::detail::co_composed_handler<void(asio::io_context::basic_executor_type<std::allocator<void>, 0>), test_nested_post_loop()::<lambda(int)>, asio::experimental::detail::co_composed_returns<>, void()>; Return = asio::experimental::detail::co_composed_returns<>]’ called on pointer returned from a mismatched allocation function [-Wmismatched-new-delete]
  169 |         [](auto state, asio::io_context& ctx) -> void
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  170 |         {
      |         ~
  171 |           co_await asio::post(ctx, asio::deferred);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  172 |           co_yield state.complete();
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~
  173 |         }, ctx), token, std::ref(ctx));
      |         ~
unit/experimental/co_composed.cpp:169:9: note: returned from ‘static void* asio::experimental::detail::co_composed_promise<Executors, Handler, Return>::operator new(std::size_t, C&&, asio::experimental::detail::co_composed_state<Executors, Handler, Return>&, Args&& ...) [with C = const nested_post<const asio::deferred_t&>(asio::io_context&, const asio::deferred_t&)::<lambda(auto:51, asio::io_context&)>&; Args = {asio::io_context&}; Executors = void(asio::io_context::basic_executor_type<std::allocator<void>, 0>); Handler = asio::experimental::detail::co_composed_handler<void(asio::io_context::basic_executor_type<std::allocator<void>, 0>), test_nested_post_loop()::<lambda(int)>, asio::experimental::detail::co_composed_returns<>, void()>; Return = asio::experimental::detail::co_composed_returns<>]’
  169 |         [](auto state, asio::io_context& ctx) -> void
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  170 |         {
      |         ~
  171 |           co_await asio::post(ctx, asio::deferred);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  172 |           co_yield state.complete();
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~
  173 |         }, ctx), token, std::ref(ctx));
      |         ~