From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2153) id 08FF8398B8A0; Thu, 17 Sep 2020 17:18:26 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 08FF8398B8A0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1600363106; bh=jSuZXBcSM0h9Aq71xO7GAsokFDW1ZB0R374nFIDiLf4=; h=From:To:Subject:Date:From; b=Vmqjvn9IPXHsvqfbhlS/StLJiA8tOsvEpvI3D3xOKuQwShu5dVztUIhhtiaybOnNM xe5/VciM8/TC/5bANrNltdHw3IKvpvd138m6vzhib4cc+uBAHVZXNpzv8MjmZFtB8+ boT4knH75smb0/xiWguFgsbG5ID/YBIlePOaLPhQ= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Jakub Jelinek To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc(refs/vendors/redhat/heads/gcc-8-branch)] libstdc++: Fix is_trivially_constructible (PR 94033) X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/vendors/redhat/heads/gcc-8-branch X-Git-Oldrev: 050ccc3b983ef6716e4cc0f6a4db21e502279093 X-Git-Newrev: ccfe790fda66df542c08ce1f1cbc287d9a487755 Message-Id: <20200917171826.08FF8398B8A0@sourceware.org> Date: Thu, 17 Sep 2020 17:18:26 +0000 (GMT) X-BeenThere: libstdc++-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 Sep 2020 17:18:26 -0000 https://gcc.gnu.org/g:ccfe790fda66df542c08ce1f1cbc287d9a487755 commit ccfe790fda66df542c08ce1f1cbc287d9a487755 Author: Jonathan Wakely Date: Wed Mar 18 23:19:12 2020 +0000 libstdc++: Fix is_trivially_constructible (PR 94033) This attempts to make is_nothrow_constructible more robust (and efficient to compile) by not depending on is_constructible. Instead the __is_constructible intrinsic is used directly. The helper class __is_nt_constructible_impl which checks whether the construction is non-throwing now takes a bool template parameter that is substituted by the result of the instrinsic. This fixes the reported bug by not using the already-instantiated (and incorrect) value of std::is_constructible. I don't think it really fixes the problem in general, because std::is_nothrow_constructible itself could already have been instantiated in a context where it gives the wrong result. A proper fix needs to be done in the compiler. Backported to the gcc-8 and gcc-9 branches to fix PR 96999. PR libstdc++/94033 * include/std/type_traits (__is_nt_default_constructible_atom): Remove. (__is_nt_default_constructible_impl): Remove. (__is_nothrow_default_constructible_impl): Remove. (__is_nt_constructible_impl): Add bool template parameter. Adjust partial specializations. (__is_nothrow_constructible_impl): Replace class template with alias template. (is_nothrow_default_constructible): Derive from alias template __is_nothrow_constructible_impl instead of __is_nothrow_default_constructible_impl. * testsuite/20_util/is_nothrow_constructible/94003.cc: New test. (cherry picked from commit b3341826531e80e02f194460b4fbe1b0541c0463) Diff: --- libstdc++-v3/include/std/type_traits | 57 ++++++++++------------ .../20_util/is_nothrow_constructible/94003.cc | 46 +++++++++++++++++ .../is_nothrow_default_constructible/96999.cc | 54 ++++++++++++++++++++ 3 files changed, 125 insertions(+), 32 deletions(-) diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits index e0394179963..6c32dd4a51f 100644 --- a/libstdc++-v3/include/std/type_traits +++ b/libstdc++-v3/include/std/type_traits @@ -915,55 +915,48 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION : public __is_move_constructible_impl<_Tp> { }; - template - struct __is_nt_default_constructible_atom - : public integral_constant + template + struct __is_nt_constructible_impl + : public false_type { }; - template::value> - struct __is_nt_default_constructible_impl; + template + struct __is_nt_constructible_impl + : public __bool_constant()...))> + { }; - template - struct __is_nt_default_constructible_impl<_Tp, true> - : public __and_<__is_array_known_bounds<_Tp>, - __is_nt_default_constructible_atom::type>> + template + struct __is_nt_constructible_impl + : public __bool_constant(std::declval<_Arg>()))> { }; template - struct __is_nt_default_constructible_impl<_Tp, false> - : public __is_nt_default_constructible_atom<_Tp> + struct __is_nt_constructible_impl + : public __bool_constant { }; - /// is_nothrow_default_constructible - template - struct is_nothrow_default_constructible - : public __and_, - __is_nt_default_constructible_impl<_Tp>> + template + struct __is_nt_constructible_impl + : public __bool_constant::type())> { }; template - struct __is_nt_constructible_impl - : public integral_constant()...))> - { }; + using __is_nothrow_constructible_impl + = __is_nt_constructible_impl<__is_constructible(_Tp, _Args...), + _Tp, _Args...>; - template - struct __is_nt_constructible_impl<_Tp, _Arg> - : public integral_constant(declval<_Arg>()))> + /// is_nothrow_constructible + template + struct is_nothrow_constructible + : public __is_nothrow_constructible_impl<_Tp, _Args...>::type { }; + /// is_nothrow_default_constructible template - struct __is_nt_constructible_impl<_Tp> - : public is_nothrow_default_constructible<_Tp> + struct is_nothrow_default_constructible + : public __is_nothrow_constructible_impl<_Tp>::type { }; - /// is_nothrow_constructible - template - struct is_nothrow_constructible - : public __and_, - __is_nt_constructible_impl<_Tp, _Args...>> - { }; template::value> struct __is_nothrow_copy_constructible_impl; diff --git a/libstdc++-v3/testsuite/20_util/is_nothrow_constructible/94003.cc b/libstdc++-v3/testsuite/20_util/is_nothrow_constructible/94003.cc new file mode 100644 index 00000000000..392a0878ba5 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/is_nothrow_constructible/94003.cc @@ -0,0 +1,46 @@ +// 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 +// . + +// { dg-options "-std=gnu++17" } +// { dg-do compile { target c++17 } } + +#include +#include + +template struct abc {}; + +template + +struct future : public abc>> {}; + +class mutation { + mutation(); + friend class std::optional; +}; + +using mutation_opt = std::optional; + +future foo(); + +template future consume_partitions() { + return foo(); +} + +future bar() { return consume_partitions(); } + +future zed(); +future apply_counter_update() { return zed(); } diff --git a/libstdc++-v3/testsuite/20_util/is_nothrow_default_constructible/96999.cc b/libstdc++-v3/testsuite/20_util/is_nothrow_default_constructible/96999.cc new file mode 100644 index 00000000000..9ec42760051 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/is_nothrow_default_constructible/96999.cc @@ -0,0 +1,54 @@ +// 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 +// . + +// { dg-options "-std=gnu++17" } +// { dg-do compile { target c++17 } } + +// PR libstdc++/96999 + +#include +#include + +struct Foo { +public: + explicit Foo(int) noexcept {} + Foo(Foo &&) noexcept = default; + Foo &operator=(Foo &&) = default; +private: + Foo() noexcept {} +}; + +struct Boo { +public: + explicit Boo(int) noexcept {} + Boo(Boo &&) noexcept = default; + Boo &operator=(Boo &&) = default; +private: + Boo() noexcept {} +}; + + +template +std::variant g(int v, int x) { + return v == 0 ? std::variant{Foo{x}} : + std::variant{Boo{x}}; +} + +int main() +{ + std::variant, std::string> err{std::string("aaa")}; +}