diff options
| -rw-r--r-- | libstdc++-v3/ChangeLog | 13 | ||||
| -rw-r--r-- | libstdc++-v3/include/std/variant | 33 | ||||
| -rw-r--r-- | libstdc++-v3/testsuite/20_util/variant/87431.cc | 71 | ||||
| -rw-r--r-- | libstdc++-v3/testsuite/20_util/variant/run.cc | 4 |
4 files changed, 118 insertions, 3 deletions
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 48f1464..fe1643d 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,18 @@ 2019-01-06 Jonathan Wakely <jwakely@redhat.com> + PR libstdc++/87431 + * include/std/variant (_Variant_storage<true, _Types...>::_M_valid): + Check is_trivially_copyable instead of is_scalar. + (variant::emplace<N, Args>(Args&&...)): If construction of the new + contained value can throw and its type is trivially copyable then + construct into a temporary variant and move from it, to provide the + strong exception safety guarantee. + (variant::emplace<N, U, Args>(initializer_list<U>, Args&&...)): + Likewise. + * testsuite/20_util/variant/87431.cc: New test. + * testsuite/20_util/variant/run.cc: Adjust test so that throwing + conversion causes valueless state. + PR libstdc++/88607 * testsuite/17_intro/headers/c++1998/charset.cc: New test. * testsuite/17_intro/headers/c++2011/charset.cc: New test. diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant index 6f2205c..83cf99e 100644 --- a/libstdc++-v3/include/std/variant +++ b/libstdc++-v3/include/std/variant @@ -439,7 +439,7 @@ namespace __variant constexpr bool _M_valid() const noexcept { - if constexpr ((is_scalar_v<_Types> && ...)) + if constexpr ((is_trivially_copyable_v<_Types> && ...)) return true; return this->_M_index != __index_type(variant_npos); } @@ -1185,6 +1185,23 @@ namespace __variant { static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); + + using type = variant_alternative_t<_Np, variant>; + // If constructing the value can throw but move assigning it can't, + // construct in a temporary and then move assign from it. This gives + // the strong exception safety guarantee, ensuring we never become + // valueless. + if constexpr (is_trivially_copyable_v<type> + && !is_nothrow_constructible_v<type, _Args...>) + { + // If move assignment cannot throw then we can provide the + // strong exception safety guarantee, and never become valueless. + variant __tmp(in_place_index<_Np>, + std::forward<_Args>(__args)...); + *this = std::move(__tmp); + return std::get<_Np>(*this); + } + this->~variant(); __try { @@ -1208,6 +1225,20 @@ namespace __variant { static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); + + using type = variant_alternative_t<_Np, variant>; + if constexpr (is_trivially_copyable_v<type> + && !is_nothrow_constructible_v<type, initializer_list<_Up>, + _Args...>) + { + // If move assignment cannot throw then we can provide the + // strong exception safety guarantee, and never become valueless. + variant __tmp(in_place_index<_Np>, __il, + std::forward<_Args>(__args)...); + *this = std::move(__tmp); + return std::get<_Np>(*this); + } + this->~variant(); __try { diff --git a/libstdc++-v3/testsuite/20_util/variant/87431.cc b/libstdc++-v3/testsuite/20_util/variant/87431.cc new file mode 100644 index 0000000..8c5c4a7 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/variant/87431.cc @@ -0,0 +1,71 @@ +// Copyright (C) 2019 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++17" } +// { dg-do run { target c++17 } } + +#include <variant> +#include <testsuite_hooks.h> + +void +test01() +{ + struct ThrowingConversion { + operator int() { throw 0; } + }; + + std::variant<float, char, int> v{'a'}; + try + { + ThrowingConversion x; + v.emplace<2>(x); + VERIFY(false); + } + catch (int) + { + VERIFY( !v.valueless_by_exception() ); + VERIFY( v.index() == 1 ); + VERIFY( std::get<1>(v) == 'a' ); + } +} + +void +test02() +{ + struct ThrowingConstructor { + ThrowingConstructor(std::initializer_list<int>, char) { throw 1; } + }; + + std::variant<float, char, ThrowingConstructor> v{'a'}; + try + { + v.emplace<2>({1, 2, 3}, '4'); + VERIFY(false); + } + catch (int) + { + VERIFY( !v.valueless_by_exception() ); + VERIFY( v.index() == 1 ); + VERIFY( std::get<1>(v) == 'a' ); + } +} + +int +main() +{ + test01(); +} diff --git a/libstdc++-v3/testsuite/20_util/variant/run.cc b/libstdc++-v3/testsuite/20_util/variant/run.cc index 1247592..c5ea7df 100644 --- a/libstdc++-v3/testsuite/20_util/variant/run.cc +++ b/libstdc++-v3/testsuite/20_util/variant/run.cc @@ -354,7 +354,7 @@ void test_hash() { struct A { - operator int() + operator string() { throw nullptr; } @@ -362,7 +362,7 @@ void test_hash() variant<int, string> v; try { - v.emplace<0>(A{}); + v.emplace<1>(A{}); } catch (nullptr_t) { |