https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96303
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:7e26e4fbd4ee618dd991c6bbf3c5403aa90d2192 commit r10-8592-g7e26e4fbd4ee618dd991c6bbf3c5403aa90d2192 Author: Jonathan Wakely <jwak...@redhat.com> Date: Fri Aug 7 20:29:11 2020 +0100 libstdc++: Fix ambiguous comparisons in __gnu_debug::bitset [PR 96303] With -pedantic the debug mode bitset has an ambiguous equality comparison operator, because it tries to compare the non-debug base to the debug object. The base object can be converted to another debug bitset, making the same operator== a candidate again. The fix is to do the comparison on both base objects, so the operator for the derived type isn't a candidate. For the inequality operator the same change should be done, but that operator can be removed entirely for C++20 because it can be synthesized by the compiler. I don't think either equality or inequality operators are really needed, because the public _GLIBCXX_STD_C::bitset base class cam always be compared using its own comparison operators. I'm not changing that here though. libstdc++-v3/ChangeLog: PR libstdc++/96303 * include/debug/bitset (bitset::operator==): Call _M_base() on right operand. (bitset::operator!=): Likewise, but don't define it at all when default comparisons are supported by the compiler. * testsuite/23_containers/bitset/operations/96303.cc: New test. (cherry picked from commit de1e3b8795e507c3cfa5b62984272628ca62a9bd)
