1 // This file is part of Eigen, a lightweight C++ template library 2 // for linear algebra. 3 // 4 // Copyright (C) 2013 Christian Seiler <christian (at) iwakd.de> 5 // 6 // This Source Code Form is subject to the terms of the Mozilla 7 // Public License v. 2.0. If a copy of the MPL was not distributed 8 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/. 9 10 #ifndef EIGEN_CXX11WORKAROUNDS_H 11 #define EIGEN_CXX11WORKAROUNDS_H 12 13 /* COMPATIBILITY CHECKS 14 * (so users of compilers that are too old get some realistic error messages) 15 */ 16 #if defined(__INTEL_COMPILER) && (__INTEL_COMPILER < 1310) 17 #error Intel Compiler only supports required C++ features since version 13.1. 18 // note that most stuff in principle works with 13.0 but when combining 19 // some features, at some point 13.0 will just fail with an internal assertion 20 #elif defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)) 21 // G++ < 4.6 by default will continue processing the source files - even if we use #error to make 22 // it error out. For this reason, we use the pragma to make sure G++ aborts at the first error 23 // it sees. Unfortunately, that is still not our #error directive, but at least the output is 24 // short enough the user has a chance to see that the compiler version is not sufficient for 25 // the funky template mojo we use. 26 #pragma GCC diagnostic error "-Wfatal-errors" 27 #error GNU C++ Compiler (g++) only supports required C++ features since version 4.6. 28 #endif 29 30 /* Check that the compiler at least claims to support C++11. It might not be sufficient 31 * because the compiler may not implement it correctly, but at least we'll know. 32 * On the other hand, visual studio still doesn't claim to support C++11 although it's 33 * compliant enugh for our purpose. 34 */ 35 #if (__cplusplus <= 199711L) && (EIGEN_COMP_MSVC < 1900) 36 #if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER) 37 #pragma GCC diagnostic error "-Wfatal-errors" 38 #endif 39 #error This library needs at least a C++11 compliant compiler. If you use g++/clang, please enable the -std=c++11 compiler flag. (-std=c++0x on older versions.) 40 #endif 41 42 namespace Eigen { 43 44 namespace internal { 45 46 /* std::get is only constexpr in C++14, not yet in C++11 47 */ 48 49 50 template<std::size_t I, class T> constexpr inline T& array_get(std::vector<T>& a) { return a[I]; } 51 template<std::size_t I, class T> constexpr inline T&& array_get(std::vector<T>&& a) { return a[I]; } 52 template<std::size_t I, class T> constexpr inline T const& array_get(std::vector<T> const& a) { return a[I]; } 53 54 /* Suppose you have a template of the form 55 * template<typename T> struct X; 56 * And you want to specialize it in such a way: 57 * template<typename S1, typename... SN> struct X<Foo<S1, SN...>> { ::: }; 58 * template<> struct X<Foo<>> { ::: }; 59 * This will work in Intel's compiler 13.0, but only to some extent in g++ 4.6, since 60 * g++ can only match templates called with parameter packs if the number of template 61 * arguments is not a fixed size (so inside the first specialization, referencing 62 * X<Foo<Sn...>> will fail in g++). On the other hand, g++ will accept the following: 63 * template<typename S...> struct X<Foo<S...>> { ::: }: 64 * as an additional (!) specialization, which will then only match the empty case. 65 * But Intel's compiler 13.0 won't accept that, it will only accept the empty syntax, 66 * so we have to create a workaround for this. 67 */ 68 #if defined(__GNUC__) && !defined(__INTEL_COMPILER) 69 #define EIGEN_TPL_PP_SPEC_HACK_DEF(mt, n) mt... n 70 #define EIGEN_TPL_PP_SPEC_HACK_DEFC(mt, n) , EIGEN_TPL_PP_SPEC_HACK_DEF(mt, n) 71 #define EIGEN_TPL_PP_SPEC_HACK_USE(n) n... 72 #define EIGEN_TPL_PP_SPEC_HACK_USEC(n) , n... 73 #else 74 #define EIGEN_TPL_PP_SPEC_HACK_DEF(mt, n) 75 #define EIGEN_TPL_PP_SPEC_HACK_DEFC(mt, n) 76 #define EIGEN_TPL_PP_SPEC_HACK_USE(n) 77 #define EIGEN_TPL_PP_SPEC_HACK_USEC(n) 78 #endif 79 80 } // end namespace internal 81 82 } // end namespace Eigen 83 84 #endif // EIGEN_CXX11WORKAROUNDS_H 85 86 /* 87 * kate: space-indent on; indent-width 2; mixedindent off; indent-mode cstyle; 88 */ 89
