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From: Tamar Christina <tnfchris@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc(refs/vendors/ARM/heads/arm-perf-staging)] libstdc++: midpoint should not constrain T is complete (LWG 3200) Date: Fri, 17 Jul 2020 13:13:22 +0000 (GMT) [thread overview] Message-ID: <20200717131322.D0C4439CF063@sourceware.org> (raw) https://gcc.gnu.org/g:5f031f9747fdfb04213c20d24f109fb5ffc877df commit 5f031f9747fdfb04213c20d24f109fb5ffc877df Author: Jonathan Wakely <jwakely@redhat.com> Date: Wed Feb 19 15:01:41 2020 +0000 libstdc++: midpoint should not constrain T is complete (LWG 3200) * include/std/numeric (midpoint(T8, T*)): Do not check for complete type during overload resolution, use static assert instead (LWG 3200). * testsuite/26_numerics/midpoint/pointer.cc: Do not test with incomplete type. * testsuite/26_numerics/midpoint/pointer_neg.cc: New test. Diff: --- libstdc++-v3/ChangeLog | 6 +++++ libstdc++-v3/include/std/numeric | 4 ++-- .../testsuite/26_numerics/midpoint/pointer.cc | 2 -- .../testsuite/26_numerics/midpoint/pointer_neg.cc | 27 ++++++++++++++++++++++ 4 files changed, 35 insertions(+), 4 deletions(-) diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 18085f3d9bd..84e5ea98022 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,11 @@ 2020-02-19 Jonathan Wakely <jwakely@redhat.com> + * include/std/numeric (midpoint(T8, T*)): Do not check for complete + type during overload resolution, use static assert instead (LWG 3200). + * testsuite/26_numerics/midpoint/pointer.cc: Do not test with + incomplete type. + * testsuite/26_numerics/midpoint/pointer_neg.cc: New test. + * include/std/span (span(T (&)[N])): Use non-deduced context to prevent first parameter from interfering with class template argument deduction (LWG 3369). diff --git a/libstdc++-v3/include/std/numeric b/libstdc++-v3/include/std/numeric index 0b0a8ff8a61..cf35191cb47 100644 --- a/libstdc++-v3/include/std/numeric +++ b/libstdc++-v3/include/std/numeric @@ -208,10 +208,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } template<typename _Tp> - constexpr - enable_if_t<__and_v<is_object<_Tp>, bool_constant<sizeof(_Tp) != 0>>, _Tp*> + constexpr enable_if_t<is_object_v<_Tp>, _Tp*> midpoint(_Tp* __a, _Tp* __b) noexcept { + static_assert( sizeof(_Tp) != 0, "type must be complete" ); return __a + (__b - __a) / 2; } _GLIBCXX_END_NAMESPACE_VERSION diff --git a/libstdc++-v3/testsuite/26_numerics/midpoint/pointer.cc b/libstdc++-v3/testsuite/26_numerics/midpoint/pointer.cc index e0b75c92739..7e75d50663c 100644 --- a/libstdc++-v3/testsuite/26_numerics/midpoint/pointer.cc +++ b/libstdc++-v3/testsuite/26_numerics/midpoint/pointer.cc @@ -19,7 +19,6 @@ // { dg-do run { target c++2a } } #include <numeric> -#include <climits> #include <testsuite_hooks.h> const int* p = nullptr; @@ -36,7 +35,6 @@ template<typename T> constexpr bool no_midpoint() static_assert(no_midpoint<void>()); static_assert(no_midpoint<int()>()); static_assert(no_midpoint<int&>()); -static_assert(no_midpoint<struct Incomplete>()); constexpr int ca[3] = {}; static_assert( std::midpoint(ca, ca+3) == ca+1 ); diff --git a/libstdc++-v3/testsuite/26_numerics/midpoint/pointer_neg.cc b/libstdc++-v3/testsuite/26_numerics/midpoint/pointer_neg.cc new file mode 100644 index 00000000000..564b1acfe27 --- /dev/null +++ b/libstdc++-v3/testsuite/26_numerics/midpoint/pointer_neg.cc @@ -0,0 +1,27 @@ +// 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 +// <http://www.gnu.org/licenses/>. + +// { dg-options "-std=gnu++2a" } +// { dg-do compile { target c++2a } } + +#include <numeric> + +// LWG 3200. midpoint should not constrain T is complete +struct Incomplete* pinc = 0; +auto p1 = std::midpoint(pinc, pinc); // { dg-error "here" } + +// { dg-error "incomplete type" "" { target *-*-* } 0 }
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