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author | Paul Keir <paul.keir@uws.ac.uk> | 2020-06-15 14:31:26 +0100 |
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committer | Jonathan Wakely <jwakely@redhat.com> | 2020-06-15 14:31:26 +0100 |
commit | eb11134d0c4e4db623aefe433c9613632ef8618e (patch) | |
tree | c1ea1f74218954d572521a5203bcda7f7a741dce /libstdc++-v3 | |
parent | e46dad5d8f09cd344911e2df428a9d38981c2351 (diff) | |
download | gcc-eb11134d0c4e4db623aefe433c9613632ef8618e.zip gcc-eb11134d0c4e4db623aefe433c9613632ef8618e.tar.gz gcc-eb11134d0c4e4db623aefe433c9613632ef8618e.tar.bz2 |
libstdc++: Fix char_traits move with overlap
Upon constexpr evaluation, char_traits move uses copy_backward, but its
last argument should be to the range end rather than its beginning.
2020-06-12 Paul Keir <paul.keir@uws.ac.uk>
* include/bits/char_traits.h (char_traits::move): constexpr move with
overlap was using copy_backward incorrectly.
* testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc:
New test.
Diffstat (limited to 'libstdc++-v3')
-rw-r--r-- | libstdc++-v3/include/bits/char_traits.h | 2 | ||||
-rw-r--r-- | libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc | 52 |
2 files changed, 53 insertions, 1 deletions
diff --git a/libstdc++-v3/include/bits/char_traits.h b/libstdc++-v3/include/bits/char_traits.h index c6da184..c623a67 100644 --- a/libstdc++-v3/include/bits/char_traits.h +++ b/libstdc++-v3/include/bits/char_traits.h @@ -196,7 +196,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION if (std::is_constant_evaluated()) { if (__s1 > __s2 && __s1 < __s2 + __n) - std::copy_backward(__s2, __s2 + __n, __s1); + std::copy_backward(__s2, __s2 + __n, __s1 + __n); else std::copy(__s2, __s2 + __n, __s1); return __s1; diff --git a/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc b/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc new file mode 100644 index 0000000..6358640 --- /dev/null +++ b/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc @@ -0,0 +1,52 @@ +// { dg-options "-std=gnu++2a" } +// { dg-do compile { target c++2a } } + +// Copyright (C) 2017-2020 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/>. + +#include <string> + +template<typename CT> + constexpr bool + test_move() + { + using char_type = typename CT::char_type; + char_type s1[3] = {1, 2, 3}; + CT::move(s1+1, s1, 2); + return s1[0]==char_type{1} && s1[1]==char_type{1} && s1[2]==char_type{2}; + } + +#ifndef __cpp_lib_constexpr_char_traits +# error Feature-test macro for constexpr char_traits is missing +#elif __cpp_lib_constexpr_char_traits != 201611 +# error Feature-test macro for constexpr char_traits has the wrong value +#endif + +static_assert( test_move<std::char_traits<char>>() ); +#ifdef _GLIBCXX_USE_WCHAR_T +static_assert( test_move<std::char_traits<wchar_t>>() ); +#endif +#ifdef _GLIBCXX_USE_CHAR8_T +static_assert( test_move<std::char_traits<char8_t>>() ); +#endif +static_assert( test_move<std::char_traits<char16_t>>() ); +static_assert( test_move<std::char_traits<char32_t>>() ); + +struct C { unsigned char c; }; +constexpr bool operator==(const C& c1, const C& c2) { return c1.c == c2.c; } +constexpr bool operator<(const C& c1, const C& c2) { return c1.c < c2.c; } +static_assert( test_move<std::char_traits<C>>() ); |