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From: Aldy Hernandez <aldyh@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc/devel/ranger] libstdc++: Make std::compare_three_way check if <=> is valid (PR 93479) Date: Wed, 17 Jun 2020 18:26:40 +0000 (GMT) [thread overview] Message-ID: <20200617182640.ED13E3954424@sourceware.org> (raw) https://gcc.gnu.org/g:83b0201035cfdc1d4d80153f4e19ec98cf059941 commit 83b0201035cfdc1d4d80153f4e19ec98cf059941 Author: Jonathan Wakely <jwakely@redhat.com> Date: Wed Jan 29 13:36:15 2020 +0000 libstdc++: Make std::compare_three_way check if <=> is valid (PR 93479) Currently types that cannot be compared using <=> but which are convertible to pointers will be compared by converting to pointers first. They should not be comparable. PR libstdc++/93479 * libsupc++/compare (__3way_builtin_ptr_cmp): Require <=> to be valid. * testsuite/18_support/comparisons/object/93479.cc: New test. Diff: --- libstdc++-v3/ChangeLog | 4 ++ libstdc++-v3/libsupc++/compare | 4 +- .../18_support/comparisons/object/93479.cc | 44 ++++++++++++++++++++++ 3 files changed, 51 insertions(+), 1 deletion(-) diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 133e216cc59..2c3d33e96ca 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,9 @@ 2020-01-29 Jonathan Wakely <jwakely@redhat.com> + PR libstdc++/93479 + * libsupc++/compare (__3way_builtin_ptr_cmp): Require <=> to be valid. + * testsuite/18_support/comparisons/object/93479.cc: New test. + * testsuite/std/ranges/access/end.cc: Do not assume test_range::end() returns the same type as test_range::begin(). Add comments. * testsuite/std/ranges/access/rbegin.cc: Likewise. diff --git a/libstdc++-v3/libsupc++/compare b/libstdc++-v3/libsupc++/compare index 117340ff184..aabd0c56530 100644 --- a/libstdc++-v3/libsupc++/compare +++ b/libstdc++-v3/libsupc++/compare @@ -525,7 +525,9 @@ namespace std // BUILTIN-PTR-THREE-WAY(T, U) template<typename _Tp, typename _Up> concept __3way_builtin_ptr_cmp - = convertible_to<_Tp, const volatile void*> + = requires(_Tp&& __t, _Up&& __u) + { static_cast<_Tp&&>(__t) <=> static_cast<_Up&&>(__u); } + && 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)); } diff --git a/libstdc++-v3/testsuite/18_support/comparisons/object/93479.cc b/libstdc++-v3/testsuite/18_support/comparisons/object/93479.cc new file mode 100644 index 00000000000..7da1df15848 --- /dev/null +++ b/libstdc++-v3/testsuite/18_support/comparisons/object/93479.cc @@ -0,0 +1,44 @@ +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// <http://www.gnu.org/licenses/>. + +// { dg-options "-std=gnu++2a" } +// { dg-do compile { target c++2a } } + +#include <compare> + +void +test01() +{ + // PR libstdc++/93479 + int i[1]; + int j[1]; + std::compare_three_way{}(i, j); // { dg-error "no match" } +} + +void +test02() +{ + struct X + { + operator const char*() const noexcept { return "!"; } + void operator<=>(X) const = delete; + void operator<=>(const void*) const = delete; + } x; + std::compare_three_way{}(x, x); // { dg-error "no match" } + std::compare_three_way{}(x, ""); // { dg-error "no match" } + std::compare_three_way{}("", x); // { dg-error "no match" } +}
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