/************************************************************************ ** ** @file lambdaconstants.h ** @author Roman Telezhynskyi ** @date 29 1, 2022 ** ** @brief ** @copyright ** This source code is part of the Valentina project, a pattern making ** program, whose allow create and modeling patterns of clothing. ** Copyright (C) 2022 Valentina project ** All Rights Reserved. ** ** Valentina 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 of the License, or ** (at your option) any later version. ** ** Valentina 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 Valentina. If not, see . ** *************************************************************************/ #ifndef LAMBDACONSTANTS_H #define LAMBDACONSTANTS_H /* given a lambda that wants to capture two constants const auto k1 = 1000; const auto k2 = 2000; int v = 0; auto lambda = [&v, &k1, &k2]() { v = k1 * k2; } Then unfortunately clang will correctly warn about unnecessary captures. And MSVC will fail to compile if you don't capture. https://stackoverflow.com/questions/52416362/unused-lambda-capture-warning-when-capture-is-actually-used An imperfect solution is to declare the lambda using the V_LAMBDA_CONSTANTS macro. auto lambda = [&v V_LAMBDA_CONSTANTS(&k1, &k2) ](){ v = k1 * k2; } This should work correctly. Most of the time. NOTE: There is no comma after the final capture variable before the V_LAMBDA_CONSTANTS macro. The macro is variadic and will work with 1 or more captures. */ #ifndef V_LAMBDA_CONSTANTS #if defined(Q_CC_MSVC) #define V_LAMBDA_CONSTANTS(...) ,__VA_ARGS__ #else #define V_LAMBDA_CONSTANTS(...) #endif #endif #endif // LAMBDACONSTANTS_H