opm-common
ConstexprAssert.hpp
1 /*
2  A compilation of the following posts:
3  http://stackoverflow.com/questions/18648069/g-doesnt-compile-constexpr-function-with-assert-in-it
4  http://ericniebler.com/2014/09/27/assert-and-constexpr-in-cxx11/
5 
6  This file is part of the Open Porous Media project (OPM).
7 
8  OPM is free software: you can redistribute it and/or modify
9  it under the terms of the GNU General Public License as published by
10  the Free Software Foundation, either version 3 of the License, or
11  (at your option) any later version.
12 
13  OPM is distributed in the hope that it will be useful,
14  but WITHOUT ANY WARRANTY; without even the implied warranty of
15  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  GNU General Public License for more details.
17 
18  You should have received a copy of the GNU General Public License
19  along with OPM. If not, see <http://www.gnu.org/licenses/>.
20 */
21 
22 #ifndef OPM_CONSTEXPR_ASSERT_HPP
23 #define OPM_CONSTEXPR_ASSERT_HPP
24 
25 #include <cassert>
26 #include <utility>
27 
28 namespace {
29 template<class Assert>
30 void constexpr_assert_failed(Assert&& a) noexcept { std::forward<Assert>(a)(); }
31 }
32 
33 // When evaluated at compile time emits a compilation error if condition is not true.
34 // Invokes the standard assert at run time.
35 #define constexpr_assert(cond) \
36  ((void)((cond) ? 0 : (constexpr_assert_failed([](){ assert(!#cond);}), 0)))
37 
38 #endif