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From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r11-3711] libstdc++: Fix divide by zero in default template argument Date: Wed, 7 Oct 2020 23:45:45 +0000 (GMT) [thread overview] Message-ID: <20201007234545.2B8D53851C2A@sourceware.org> (raw) https://gcc.gnu.org/g:6ae17a3b6835b30102607d45ac89c7a668e2c8d4 commit r11-3711-g6ae17a3b6835b30102607d45ac89c7a668e2c8d4 Author: Jonathan Wakely <jwakely@redhat.com> Date: Thu Oct 8 00:34:56 2020 +0100 libstdc++: Fix divide by zero in default template argument libstdc++-v3/ChangeLog: * include/bits/random.h (__detail::_Mod): Avoid divide by zero. * testsuite/26_numerics/random/linear_congruential_engine/operators/call.cc: New test. Diff: --- libstdc++-v3/include/bits/random.h | 2 +- .../linear_congruential_engine/operators/call.cc | 27 ++++++++++++++++++++++ 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/libstdc++-v3/include/bits/random.h b/libstdc++-v3/include/bits/random.h index 4a6558c966a..920f3d91513 100644 --- a/libstdc++-v3/include/bits/random.h +++ b/libstdc++-v3/include/bits/random.h @@ -109,7 +109,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template<typename _Tp, _Tp __m, _Tp __a, _Tp __c, bool __big_enough = (!(__m & (__m - 1)) || (_Tp(-1) - __c) / __a >= __m - 1), - bool __schrage_ok = __m % __a < __m / __a> + bool __schrage_ok = __a != 0 && __m % __a < __m / __a> struct _Mod { typedef typename _Select_uint_least_t<std::__lg(__a) diff --git a/libstdc++-v3/testsuite/26_numerics/random/linear_congruential_engine/operators/call.cc b/libstdc++-v3/testsuite/26_numerics/random/linear_congruential_engine/operators/call.cc new file mode 100644 index 00000000000..d1fff6d0a5d --- /dev/null +++ b/libstdc++-v3/testsuite/26_numerics/random/linear_congruential_engine/operators/call.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-do compile { target c++11 } } + +#include <random> + +unsigned +test01() +{ + std::linear_congruential_engine<unsigned, 0, 0, 0> l; + return l(); // this used to result in divide by zero +}
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