https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94759
--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Iain D Sandoe <ia...@gcc.gnu.org>: https://gcc.gnu.org/g:b9c91b7f3279e23aed965c05197acf3b6f439f8d commit r10-8004-gb9c91b7f3279e23aed965c05197acf3b6f439f8d Author: Iain Sandoe <i...@sandoe.co.uk> Date: Tue Apr 28 00:27:47 2020 +0100 coroutines: Fix handling of non-class coroutine returns [PR94759] From the standard: The header <coroutine> defines the primary template coroutine_traits such that if ArgTypes is a parameter pack of types and if the qualified-id R::promise_type is valid and denotes a type, then coroutine_traits<R,ArgTypes...> has the following publicly accessible member: using promise_type = typename R::promise_type; this should not prevent more specialised cases and the following code should be accepted, but is currently rejected with: 'error: coroutine return type âvoidâ is not a class' This is because the check for non-class-ness of the return value was in the wrong place; it needs to be carried out in a SFINAE context. The following patch removes the restriction in the traits template instantiation and allows for the case that the ramp function could return void. The <coroutine> header is amended to implement the required functionality. gcc/cp/ChangeLog: 2020-04-28 Iain Sandoe <i...@sandoe.co.uk> PR c++/94759 * coroutines.cc (coro_promise_type_found_p): Do not exclude non-classes here (this needs to be handled in the coroutine header). (morph_fn_to_coro): Allow for the case where the coroutine returns void. gcc/testsuite/ChangeLog: 2020-04-28 Iain Sandoe <i...@sandoe.co.uk> PR c++/94759 * g++.dg/coroutines/coro-bad-alloc-00-bad-op-new.C: Adjust for updated error messages. * g++.dg/coroutines/coro-bad-alloc-01-bad-op-del.C: Likewise. * g++.dg/coroutines/coro-bad-alloc-02-no-op-new-nt.C: Likewise. * g++.dg/coroutines/coro-missing-promise.C: Likewise. * g++.dg/coroutines/pr93458-5-bad-coro-type.C: Liekwise. * g++.dg/coroutines/torture/co-ret-17-void-ret-coro.C: New test. libstdc++-v3/ChangeLog: 2020-04-28 Jonathan Wakely <jwak...@redhat.com> Iain Sandoe <i...@sandoe.co.uk> PR c++/94759 * include/std/coroutine: Implement handing for non- class coroutine return types.
