mirror of
https://github.com/gcc-mirror/gcc.git
synced 2026-05-06 23:25:24 +02:00
3d3145e9e1
Some _Safe_iterator member functions define a variable of non-literal type __gnu_cxx::__scoped_lock, which automatically disqualifies them from being constexpr in C++20 mode even if that code path is never constant evaluated. This restriction was lifted by P2242R3 for C++23, but we need to work around it in C++20 mode. To that end this patch defines a pair of macros that encapsulate the lambda-based workaround mentioned in that paper and uses it to make these functions valid C++20 constexpr functions. The augmented std::vector test element_access/constexpr.cc now successfully compiles in C++20 mode with -D_GLIBCXX_DEBUG (and it should test all member functions modified by this patch). PR libstdc++/109536 libstdc++-v3/ChangeLog: * include/debug/safe_base.h (_Safe_sequence_base::_M_swap): Remove _GLIBCXX20_CONSTEXPR from non-inline member function. * include/debug/safe_iterator.h (_GLIBCXX20_CONSTEXPR_NON_LITERAL_SCOPE_BEGIN): Define. (_GLIBCXX20_CONSTEXPR_NON_LITERAL_SCOPE_END): Define. (_Safe_iterator::operator=): Use them around the code path that defines a variable of type __gnu_cxx::__scoped_lock. (_Safe_iterator::operator++): Likewise. (_Safe_iterator::operator--): Likewise. (_Safe_iterator::operator+=): Likewise. (_Safe_iterator::operator-=): Likewise. * testsuite/23_containers/vector/element_access/constexpr.cc (test_iterators): Test more iterator operations. * testsuite/23_containers/vector/bool/element_access/constexpr.cc (test_iterators): Likewise. * testsuite/std/ranges/adaptors/all.cc (test08) [_GLIBCXX_DEBUG]: Remove. Reviewed-by: Jonathan Wakely <jwakely@redhat.com>