From 8572edc828f6d1e7c8243f901fe7c96f62a11a8e Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Wed, 28 Oct 2020 12:28:08 -0400 Subject: [PATCH] libstdc++: Fix arithmetic bug in year_month_weekday conversion [PR96713] The conversion function year_month_weekday::operator sys_days computes the offset in days from the first weekday of the month with: days{(index()-1)*7} ^~~~~~~~~~~~~ type 'unsigned' We want the above to yield -7d when index() is 0u, but our 'days' alias is based on long instead of int, so the conversion from unsigned to the underlying type of 'days' instead yields a large positive value. This patch fixes this by casting the result of index() to int so that the initializer is sign-extended in the conversion to long. The added testcase also verifies we do the right thing when index() == 5. libstdc++-v3/ChangeLog: PR libstdc++/96713 * include/std/chrono (year_month_weekday::operator sys_days): Cast the result of index() to int so that the initializer for days{} is sign-extended when it's converted to the underlying type. * testsuite/std/time/year_month_weekday/3.cc: New test. --- libstdc++-v3/include/std/chrono | 3 +- .../std/time/year_month_weekday/3.cc | 65 +++++++++++++++++++ 2 files changed, 67 insertions(+), 1 deletion(-) create mode 100644 libstdc++-v3/testsuite/std/time/year_month_weekday/3.cc diff --git a/libstdc++-v3/include/std/chrono b/libstdc++-v3/include/std/chrono index 7539d7184ea..020982d0b78 100644 --- a/libstdc++-v3/include/std/chrono +++ b/libstdc++-v3/include/std/chrono @@ -2719,7 +2719,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION operator sys_days() const noexcept { auto __d = sys_days{year() / month() / 1}; - return __d + (weekday() - chrono::weekday(__d) + days{(index()-1)*7}); + return __d + (weekday() - chrono::weekday(__d) + + days{(static_cast(index())-1)*7}); } explicit constexpr diff --git a/libstdc++-v3/testsuite/std/time/year_month_weekday/3.cc b/libstdc++-v3/testsuite/std/time/year_month_weekday/3.cc new file mode 100644 index 00000000000..cccaccef211 --- /dev/null +++ b/libstdc++-v3/testsuite/std/time/year_month_weekday/3.cc @@ -0,0 +1,65 @@ +// { dg-options "-std=gnu++2a" } +// { dg-do compile { target c++2a } } + +// 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 +// . + +// PR libstdc++/97613 +// Test year_month_weekday to sys_days conversion for extreme values of index(). + +#include + +void +test01() +{ + using namespace std::chrono; + using ymd = year_month_day; + + static_assert(ymd{sys_days{2020y/January/Sunday[0]}} == 2019y/December/29); + static_assert(ymd{sys_days{2020y/January/Monday[0]}} == 2019y/December/30); + static_assert(ymd{sys_days{2020y/January/Tuesday[0]}} == 2019y/December/31); + static_assert(ymd{sys_days{2020y/January/Wednesday[0]}} == 2019y/December/25); + static_assert(ymd{sys_days{2020y/January/Thursday[0]}} == 2019y/December/26); + static_assert(ymd{sys_days{2020y/January/Friday[0]}} == 2019y/December/27); + static_assert(ymd{sys_days{2020y/January/Saturday[0]}} == 2019y/December/28); + + static_assert((2020y).is_leap()); + static_assert(ymd{sys_days{2020y/March/Sunday[0]}} == 2020y/February/23); + static_assert(ymd{sys_days{2020y/March/Monday[0]}} == 2020y/February/24); + static_assert(ymd{sys_days{2020y/March/Tuesday[0]}} == 2020y/February/25); + static_assert(ymd{sys_days{2020y/March/Wednesday[0]}} == 2020y/February/26); + static_assert(ymd{sys_days{2020y/March/Thursday[0]}} == 2020y/February/27); + static_assert(ymd{sys_days{2020y/March/Friday[0]}} == 2020y/February/28); + static_assert(ymd{sys_days{2020y/March/Saturday[0]}} == 2020y/February/29); + + static_assert(!(2019y).is_leap()); + static_assert(ymd{sys_days{2019y/March/Sunday[0]}} == 2019y/February/24); + static_assert(ymd{sys_days{2019y/March/Monday[0]}} == 2019y/February/25); + static_assert(ymd{sys_days{2019y/March/Tuesday[0]}} == 2019y/February/26); + static_assert(ymd{sys_days{2019y/March/Wednesday[0]}} == 2019y/February/27); + static_assert(ymd{sys_days{2019y/March/Thursday[0]}} == 2019y/February/28); + static_assert(ymd{sys_days{2019y/March/Friday[0]}} == 2019y/February/22); + static_assert(ymd{sys_days{2019y/March/Saturday[0]}} == 2019y/February/23); + + static_assert(ymd{sys_days{2020y/December/Sunday[5]}} == 2021y/January/3); + static_assert(ymd{sys_days{2020y/December/Monday[5]}} == 2021y/January/4); + static_assert(ymd{sys_days{2020y/December/Tuesday[5]}} == 2020y/December/29); + static_assert(ymd{sys_days{2020y/December/Wednesday[5]}} == 2020y/December/30); + static_assert(ymd{sys_days{2020y/December/Thursday[5]}} == 2020y/December/31); + static_assert(ymd{sys_days{2020y/December/Friday[5]}} == 2021y/January/1); + static_assert(ymd{sys_days{2020y/December/Saturday[5]}} == 2021y/January/2); +} -- 2.30.2