1 // This file is part of Eigen, a lightweight C++ template library
2 // for linear algebra.
3 //
4 // Copyright (C) 2013 Christian Seiler <christian@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
array_get(std::vector<T> & a)50 template<std::size_t I, class T> constexpr inline T& array_get(std::vector<T>& a) { return a[I]; }
array_get(std::vector<T> && a)51 template<std::size_t I, class T> constexpr inline T&& array_get(std::vector<T>&& a) { return a[I]; }
array_get(std::vector<T> const & a)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