From f214ffb336d582a66149068a2a96b7fcf395b5de Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Wed, 29 Jan 2020 13:56:49 +0000 Subject: [PATCH] libstdc++: Simplify constraints on std::compare_three_way The __3way_builtin_ptr_cmp concept can use three_way_comparable_with to check whether <=> is valid. Doing that makes it obvious that the disjunction on compare_three_way::operator() is redundant, because the second constraint subsumes the first. The workaround for PR c++/91073 can also be removed as that bug is fixed now. * libsupc++/compare (__detail::__3way_builtin_ptr_cmp): Use three_way_comparable_with. (__detail::__3way_cmp_with): Remove workaround for fixed bug. (compare_three_way::operator()): Remove redundant constraint from requires-clause. (__detail::_Synth3way::operator()): Use three_way_comparable_with instead of workaround. * testsuite/18_support/comparisons/object/93479.cc: Prune extra output due to simplified constraints on compare_three_way::operator(). --- libstdc++-v3/ChangeLog | 10 ++++++++++ libstdc++-v3/libsupc++/compare | 12 +++--------- .../testsuite/18_support/comparisons/object/93479.cc | 2 ++ 3 files changed, 15 insertions(+), 9 deletions(-) diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 2c3d33e96ca..e9a8a677e4c 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,15 @@ 2020-01-29 Jonathan Wakely + * libsupc++/compare (__detail::__3way_builtin_ptr_cmp): Use + three_way_comparable_with. + (__detail::__3way_cmp_with): Remove workaround for fixed bug. + (compare_three_way::operator()): Remove redundant constraint from + requires-clause. + (__detail::_Synth3way::operator()): Use three_way_comparable_with + instead of workaround. + * testsuite/18_support/comparisons/object/93479.cc: Prune extra + output due to simplified constraints on compare_three_way::operator(). + PR libstdc++/93479 * libsupc++/compare (__3way_builtin_ptr_cmp): Require <=> to be valid. * testsuite/18_support/comparisons/object/93479.cc: New test. diff --git a/libstdc++-v3/libsupc++/compare b/libstdc++-v3/libsupc++/compare index aabd0c56530..a7a29ef0440 100644 --- a/libstdc++-v3/libsupc++/compare +++ b/libstdc++-v3/libsupc++/compare @@ -525,26 +525,20 @@ namespace std // BUILTIN-PTR-THREE-WAY(T, U) template concept __3way_builtin_ptr_cmp - = requires(_Tp&& __t, _Up&& __u) - { static_cast<_Tp&&>(__t) <=> static_cast<_Up&&>(__u); } + = three_way_comparable_with<_Tp, _Up> && convertible_to<_Tp, const volatile void*> && convertible_to<_Up, const volatile void*> && ! requires(_Tp&& __t, _Up&& __u) { operator<=>(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)); } && ! requires(_Tp&& __t, _Up&& __u) { static_cast<_Tp&&>(__t).operator<=>(static_cast<_Up&&>(__u)); }; - - // FIXME: workaround for PR c++/91073 - template - concept __3way_cmp_with = three_way_comparable_with<_Tp, _Up>; } // namespace __detail // [cmp.object], typename compare_three_way struct compare_three_way { template - requires (__detail::__3way_cmp_with<_Tp, _Up> - || __detail::__3way_builtin_ptr_cmp<_Tp, _Up>) + requires three_way_comparable_with<_Tp, _Up> constexpr auto operator()(_Tp&& __t, _Up&& __u) const noexcept { @@ -919,7 +913,7 @@ namespace std { __u < __t } -> convertible_to; } { - if constexpr (__3way_cmp_with<_Tp, _Up>) + if constexpr (three_way_comparable_with<_Tp, _Up>) return __t <=> __u; else { diff --git a/libstdc++-v3/testsuite/18_support/comparisons/object/93479.cc b/libstdc++-v3/testsuite/18_support/comparisons/object/93479.cc index 7da1df15848..f4f0a36685b 100644 --- a/libstdc++-v3/testsuite/18_support/comparisons/object/93479.cc +++ b/libstdc++-v3/testsuite/18_support/comparisons/object/93479.cc @@ -42,3 +42,5 @@ test02() std::compare_three_way{}(x, ""); // { dg-error "no match" } std::compare_three_way{}("", x); // { dg-error "no match" } } + +// { dg-prune-output "in requirements with" } -- 2.30.2