From 3e4ebee42c8af0ba0042a65de41a6188212ffe3c Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Fri, 24 Nov 2017 00:00:46 +0000 Subject: Add [[nodiscard]] attribute to std::launder * libsupc++/new (launder): Add nodiscard attribute. * testsuite/18_support/launder/nodiscard.cc: New test. git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@255127 138bc75d-0d04-0410-961f-82ee72b054a4 --- libstdc++-v3/ChangeLog | 3 +++ libstdc++-v3/libsupc++/new | 4 +-- .../testsuite/18_support/launder/nodiscard.cc | 29 ++++++++++++++++++++++ 3 files changed, 34 insertions(+), 2 deletions(-) create mode 100644 libstdc++-v3/testsuite/18_support/launder/nodiscard.cc diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 3b2dad016fd..d098ccc7416 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,8 @@ 2017-11-23 Jonathan Wakely + * libsupc++/new (launder): Add nodiscard attribute. + * testsuite/18_support/launder/nodiscard.cc: New test. + * include/bits/fs_path.h (path::empty): Add nodiscard attribute. * include/bits/range_access.h (empty): Likewise. * include/std/string_view (basic_string_view::empty): Likewise. diff --git a/libstdc++-v3/libsupc++/new b/libstdc++-v3/libsupc++/new index 795b33c4e6a..0e408b1019c 100644 --- a/libstdc++-v3/libsupc++/new +++ b/libstdc++-v3/libsupc++/new @@ -176,7 +176,7 @@ inline void operator delete[](void*, void*) _GLIBCXX_USE_NOEXCEPT { } //@} } // extern "C++" -#if __cplusplus > 201402L +#if __cplusplus >= 201703L #if __GNUC__ >= 7 # define _GLIBCXX_HAVE_BUILTIN_LAUNDER 1 #elif defined __has_builtin @@ -192,7 +192,7 @@ namespace std #define __cpp_lib_launder 201606 /// Pointer optimization barrier [ptr.launder] template - constexpr _Tp* + [[nodiscard]] constexpr _Tp* launder(_Tp* __p) noexcept { return __builtin_launder(__p); } diff --git a/libstdc++-v3/testsuite/18_support/launder/nodiscard.cc b/libstdc++-v3/testsuite/18_support/launder/nodiscard.cc new file mode 100644 index 00000000000..1741465abed --- /dev/null +++ b/libstdc++-v3/testsuite/18_support/launder/nodiscard.cc @@ -0,0 +1,29 @@ +// Copyright (C) 2017 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 + +struct A { const int i; }; + +void +test01(A* a) +{ + std::launder(a); // { dg-warning "ignoring return value" } +} -- cgit v1.2.3