[Bug libstdc++/103726] --disable-hosted-libstdcxx (freestanding C++) does not provide <coroutine> as what standard requires
cvs-commit at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Tue Jan 11 13:29:39 GMT 2022
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103726
--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:
https://gcc.gnu.org/g:265d3e1a4e3d6c71d354f859302f023dc2d33f62
commit r12-6474-g265d3e1a4e3d6c71d354f859302f023dc2d33f62
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Jan 10 20:48:53 2022 +0000
libstdc++: Install <coroutine> header for freestanding [PR103726]
The standard says that <coroutine> should be present for freestanding.
That was intentionally left out of the initial implementation, but can
be done without much trouble. The header should be moved to libsupc++ at
some point in stage 1.
The standard also says that <coroutine> defines a std::hash
specialization, which was missing from our implementation. That's a
problem for freestanding (see LWG 3653) so only do that for hosted.
We can use concepts to constrain the __coroutine_traits_impl base class
when compiled with concepts enabled. In a pure C++20 implementation we
would not need that base class at all and could just use a constrained
partial specialization of coroutine_traits. But the absence of the
__coroutine_traits_impl<R, void> base would create an ABI difference
between the non-standard C++14/C++17 support for coroutines and the same
code compiled as C++20. If we drop support for <coroutine> pre-C++20 we
should revisit this.
libstdc++-v3/ChangeLog:
PR libstdc++/103726
* include/Makefile.am: Install <coroutine> for freestanding.
* include/Makefile.in: Regenerate.
* include/std/coroutine: Adjust headers and preprocessor
conditions.
(__coroutine_traits_impl): Use concepts when available.
[_GLIBCXX_HOSTED] (hash<coroutine_handle>): Define.
More information about the Gcc-bugs
mailing list