https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119125
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Tomasz Kaminski <tkami...@gcc.gnu.org>: https://gcc.gnu.org/g:0e93f7cd4ed0cf6bcfda90ed4dcad51a1f65b4b6 commit r16-618-g0e93f7cd4ed0cf6bcfda90ed4dcad51a1f65b4b6 Author: Tomasz KamiÅski <tkami...@redhat.com> Date: Mon May 12 10:01:22 2025 +0200 libstdc++: Implement C++26 copyable_function [PR119125] This patch implements C++26 copyable_function as specified in P2548R6. It also implements LWG 4255 that adjust move_only_function so constructing from empty copyable_function, produces empty functor. This falls from existing checks, after specializing __is_polymorphic_function_v for copyable_function specializations. For compatible invoker signatures, the move_only_function may be constructed from copyable_funciton without double indirection. To achieve that we derive _Cpy_base from _Mo_base, and specialize __is_polymorphic_function_v for copyable_function. Similary copyable_functions with compatible signatures can be converted without double indirection. As we starting to use _Op::_Copy operation from the _M_manage function, invocations of that functions may now throw exceptions, so noexcept needs to be removed from the signature of stored _M_manage pointers. This also affects operations in _Mo_base, however we already wrap _M_manage invocations in noexcept member functions (_M_move, _M_destroy, swap). PR libstdc++/119125 libstdc++-v3/ChangeLog: * doc/doxygen/stdheader.cc: Addded cpyfunc_impl.h header. * include/Makefile.am: Add bits cpyfunc_impl.h. * include/Makefile.in: Add bits cpyfunc_impl.h. * include/bits/cpyfunc_impl.h: New file. * include/bits/mofunc_impl.h: Mention LWG 4255. * include/bits/move_only_function.h: Update header description and change guard to also check __glibcxx_copyable_function. (_Manager::_Func): Remove noexcept. (std::__is_polymorphic_function_v<move_only_function<_Tp>>) (__variant::_Never_valueless_alt<std::move_only_function<_Signature...>>) (move_only_function) [__glibcxx_move_only_function]: Adjust guard. (std::__is_polymorphic_function_v<copyable_function<_Tp>>) (__variant::_Never_valueless_alt<std::copyable_function<_Signature...>>) (__polyfunc::_Cpy_base, std::copyable_function) [__glibcxx_copyable_function]: Define. * include/bits/version.def: Define copyable_function. * include/bits/version.h: Regenerate. * include/std/functional: Define __cpp_lib_copyable_function. * src/c++23/std.cc.in (copyable_function) [__cpp_lib_copyable_function]: Export. * testsuite/20_util/copyable_function/call.cc: New test based on move_only_function tests. * testsuite/20_util/copyable_function/cons.cc: New test based on move_only_function tests. * testsuite/20_util/copyable_function/conv.cc: New test based on move_only_function tests. * testsuite/20_util/copyable_function/copy.cc: New test. * testsuite/20_util/copyable_function/move.cc: New test based on move_only_function tests. Reviewed-by: Jonathan Wakely <jwak...@redhat.com> Signed-off-by: Tomasz KamiÅski <tkami...@redhat.com>
