https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103904
--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-11 branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: https://gcc.gnu.org/g:3273e704d04a98bcfccdc93c8d07e88f2b032043 commit r11-9561-g3273e704d04a98bcfccdc93c8d07e88f2b032043 Author: Patrick Palka <ppa...@redhat.com> Date: Fri Feb 11 15:39:06 2022 -0500 libstdc++: Back out some changes from P2325R3 backport [PR103904] In the P2325R3 backport r11-9555 the relaxation of the constraints on the partial specialization of __box (which is semantically equivalent to the primary template, only more space efficient) means some specializations of __box will now use the partial specialization instead of the primary template, which constitutes an ABI change unsuitable for a release branch. So this patch reverts this constraint change, which isn't needed for correctness anyway. Similarly, the change to use __non_propagating_cache for the data member split_view::_M_current (so that it's always default-initializable) also constitutes an unsuitable ABI change. This patch reverts this change too, and instead further constrains split_view's default constructor to require that we can default-initialize _M_current. PR libstdc++/103904 libstdc++-v3/ChangeLog: * include/std/ranges (__detail::__box): Revert r11-9555 changes to the constraints on the partial specialization and the now-unnecessary special member functions. (__detail::__non_propagating_cache::operator=): Remove now-unused overload added by r11-9555. (split_view::_OuterIter::__current): Adjust after reverting the r11-9555 change to the type of _M_current. (split_view::_M_current): Revert r11-9555 change to its type. (split_view::split_view): Constrain the default constructor further. * testsuite/std/ranges/adaptors/detail/copyable_box.cc: Disable now-irrelevant test for the r11-9555 changes to the partial specialization of __box.
