mirror/gcc
2
0
Fork 0
mirror of git://gcc.gnu.org/git/gcc.git synced 2025-04-10 13:31:04 +08:00
Code Issues Packages Projects Releases Wiki Activity

libstdc++: Make std::compare_three_way check if <=> is valid (PR 93479)

Browse Source 
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.
This commit is contained in:
Jonathan Wakely 2020-01-29 13:36:15 +00:00
parent 5cd2e126f5
commit 83b0201035
3 changed files with 51 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
libstdc++-v3/ChangeLog
View File

@ -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.

4
libstdc++-v3/libsupc++/compare
View File

@ -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)); }

44
libstdc++-v3/testsuite/18_support/comparisons/object/93479.cc Normal file
View File

@ -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" }
}