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* [gcc(refs/users/giulianob/heads/autopar_rebase2)] libstdc++: Fix ambiguous comparisons in __gnu_debug::bitset [PR 96303]
@ 2020-08-18 1:33 Giuliano Belinassi
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From: Giuliano Belinassi @ 2020-08-18 1:33 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:f2e7661aad6ca8b75e9c9c5dc7eb489df52646f6
commit f2e7661aad6ca8b75e9c9c5dc7eb489df52646f6
Author: Jonathan Wakely <jwakely@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.
Diff:
---
libstdc++-v3/include/debug/bitset | 6 +++--
.../23_containers/bitset/operations/96303.cc | 31 ++++++++++++++++++++++
2 files changed, 35 insertions(+), 2 deletions(-)
diff --git a/libstdc++-v3/include/debug/bitset b/libstdc++-v3/include/debug/bitset
index fb498012605..1b8dc6d422c 100644
--- a/libstdc++-v3/include/debug/bitset
+++ b/libstdc++-v3/include/debug/bitset
@@ -353,11 +353,13 @@ namespace __debug
bool
operator==(const bitset<_Nb>& __rhs) const _GLIBCXX_NOEXCEPT
- { return _M_base() == __rhs; }
+ { return _M_base() == __rhs._M_base(); }
+#if __cpp_impl_three_way_comparison < 201907L
bool
operator!=(const bitset<_Nb>& __rhs) const _GLIBCXX_NOEXCEPT
- { return _M_base() != __rhs; }
+ { return _M_base() != __rhs._M_base(); }
+#endif
using _Base::test;
using _Base::all;
diff --git a/libstdc++-v3/testsuite/23_containers/bitset/operations/96303.cc b/libstdc++-v3/testsuite/23_containers/bitset/operations/96303.cc
new file mode 100644
index 00000000000..ab31e3c47d5
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/bitset/operations/96303.cc
@@ -0,0 +1,31 @@
+// 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 -pedantic" }
+// { dg-do compile { target c++2a } }
+
+#include <debug/bitset>
+
+bool
+test01()
+{
+ __gnu_debug::bitset<1> b;
+ // PR libstdc++/96303
+ bool eq = b == b;
+ bool ne = b != b;
+ return eq && !ne;
+}
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