From 3d18dc9db0513eae3dba69fb143e35cbe8c34f20 Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Sun, 11 Nov 2018 05:17:03 +0000 Subject: [PATCH] Implement P0318R1 unwrap_ref_decay and unwrap_reference Implement P0318R1 unwrap_ref_decay and unwrap_reference * include/std/type_traits (unwrap_reference, unwrap_reference_t) (unwrap_ref_decay, unwrap_ref_decay_t): New traits and aliases. * testsuite/20_util/unwrap_reference/1.cc: New test. * testsuite/20_util/unwrap_reference/2.cc: New test. From-SVN: r266010 --- libstdc++-v3/ChangeLog | 6 ++ libstdc++-v3/include/std/type_traits | 14 +++++ .../testsuite/20_util/unwrap_reference/1.cc | 58 +++++++++++++++++++ .../testsuite/20_util/unwrap_reference/2.cc | 51 ++++++++++++++++ 4 files changed, 129 insertions(+) create mode 100644 libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc create mode 100644 libstdc++-v3/testsuite/20_util/unwrap_reference/2.cc diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 967aa5bc53d..ceaac2db195 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,11 @@ 2018-11-11 Jonathan Wakely + Implement P0318R1 unwrap_ref_decay and unwrap_reference + * include/std/type_traits (unwrap_reference, unwrap_reference_t) + (unwrap_ref_decay, unwrap_ref_decay_t): New traits and aliases. + * testsuite/20_util/unwrap_reference/1.cc: New test. + * testsuite/20_util/unwrap_reference/2.cc: New test. + Implement P1007R3 std::assume_aligned * include/std/memory (assume_aligned): Implement for C++17. * testsuite/20_util/assume_aligned/1.cc: New test. diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits index 86b58ccf225..60094f9897b 100644 --- a/libstdc++-v3/include/std/type_traits +++ b/libstdc++-v3/include/std/type_traits @@ -3015,6 +3015,20 @@ template template using type_identity_t = typename type_identity<_Tp>::type; + /// Unwrap a reference_wrapper + template + struct unwrap_reference { using type = _Tp; }; + + template + struct unwrap_reference> { using type = _Tp&; }; + + /// Decay type and if it's a reference_wrapper, unwrap it + template + struct unwrap_ref_decay : unwrap_reference> { }; + + template + using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type; + #endif // C++2a _GLIBCXX_END_NAMESPACE_VERSION diff --git a/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc b/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc new file mode 100644 index 00000000000..d259db91418 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc @@ -0,0 +1,58 @@ +// Copyright (C) 2018 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++2a" } +// { dg-do compile { target c++2a } } + +#include + +template struct expect_same; +template struct expect_same : std::true_type { }; + +template + constexpr bool check() + { + using std::unwrap_reference; + using T2 = typename unwrap_reference::type; + static_assert(expect_same::type>::value); + return expect_same::value; + } + +void +test01() +{ + static_assert( check() ); + static_assert( check() ); + static_assert( check() ); + static_assert( check() ); + static_assert( check() ); + + // reference_wrapper types should get unwrapped: + static_assert( check, int&>() ); + static_assert( check, const int&>() ); + static_assert( check, long&>() ); + + // But not cv-qualified reference_wrapper types: + static_assert( check>() ); + static_assert( check>() ); + static_assert( check>() ); + + // Or references to reference_wrapper types: + static_assert( check&>() ); + static_assert( check&&>() ); + static_assert( check&>() ); +} diff --git a/libstdc++-v3/testsuite/20_util/unwrap_reference/2.cc b/libstdc++-v3/testsuite/20_util/unwrap_reference/2.cc new file mode 100644 index 00000000000..47bfa71975e --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/unwrap_reference/2.cc @@ -0,0 +1,51 @@ +// Copyright (C) 2018 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++2a" } +// { dg-do compile { target c++2a } } + +#include + +template struct expect_same; +template struct expect_same : std::true_type { }; + +template> + constexpr bool check() + { + using T2 = typename std::unwrap_ref_decay::type; + static_assert(expect_same>::value); + return expect_same::value; + } + +void +test01() +{ + static_assert( check() ); + static_assert( check() ); + static_assert( check() ); + static_assert( check() ); + static_assert( check() ); + + // reference_wrapper types (including cv and references) get unwrapped: + static_assert( check, int&>() ); + static_assert( check&, int&>() ); + static_assert( check, int&>() ); + static_assert( check&, int&>() ); + static_assert( check, const int&>() ); + static_assert( check&, const int&>() ); + static_assert( check, long&>() ); +} -- 2.30.2