2 * Copyright 2014 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #ifndef FOLLY_PORTABILITY_H_
18 #define FOLLY_PORTABILITY_H_
20 #ifndef FOLLY_NO_CONFIG
21 #include "folly-config.h"
24 #if FOLLY_HAVE_FEATURES_H
28 #include "CPortability.h"
30 #if FOLLY_HAVE_SCHED_H
32 #ifndef FOLLY_HAVE_PTHREAD_YIELD
33 #define pthread_yield sched_yield
38 // MaxAlign: max_align_t isn't supported by gcc
40 struct MaxAlign { char c; } __attribute__((aligned));
42 # error Cannot define MaxAlign on this platform
47 #if defined(__clang__) || defined(__GNUC__)
48 # define FOLLY_NORETURN __attribute__((noreturn))
50 # define FOLLY_NORETURN
54 // portable version check
56 # if defined __GNUC__ && defined __GNUC_MINOR__
57 # define __GNUC_PREREQ(maj, min) ((__GNUC__ << 16) + __GNUC_MINOR__ >= \
58 ((maj) << 16) + (min))
60 # define __GNUC_PREREQ(maj, min) 0
65 /* Define macro wrappers for C++11's "final" and "override" keywords, which
66 * are supported in gcc 4.7 but not gcc 4.6. */
67 #if !defined(FOLLY_FINAL) && !defined(FOLLY_OVERRIDE)
68 # if defined(__clang__) || __GNUC_PREREQ(4, 7)
69 # define FOLLY_FINAL final
70 # define FOLLY_OVERRIDE override
72 # define FOLLY_FINAL /**/
73 # define FOLLY_OVERRIDE /**/
78 // Define to 1 if you have the `preadv' and `pwritev' functions, respectively
79 #if !defined(FOLLY_HAVE_PREADV) && !defined(FOLLY_HAVE_PWRITEV)
80 # if defined(__GLIBC_PREREQ)
81 # if __GLIBC_PREREQ(2, 10)
82 # define FOLLY_HAVE_PREADV 1
83 # define FOLLY_HAVE_PWRITEV 1
88 // It turns out that GNU libstdc++ and LLVM libc++ differ on how they implement
89 // the 'std' namespace; the latter uses inline namepsaces. Wrap this decision
90 // up in a macro to make forward-declarations easier.
92 #define FOLLY_NAMESPACE_STD_BEGIN _LIBCPP_BEGIN_NAMESPACE_STD
93 #define FOLLY_NAMESPACE_STD_END _LIBCPP_END_NAMESPACE_STD
95 #define FOLLY_NAMESPACE_STD_BEGIN namespace std {
96 #define FOLLY_NAMESPACE_STD_END }
99 // Some platforms lack clock_gettime(2) and clock_getres(2). Inject our own
100 // versions of these into the global namespace.
101 #if FOLLY_HAVE_CLOCK_GETTIME
104 #include "folly/detail/Clock.h"
107 // Provide our own std::__throw_* wrappers for platforms that don't have them
108 #if FOLLY_HAVE_BITS_FUNCTEXCEPT_H
109 #include <bits/functexcept.h>
111 #include "folly/detail/FunctionalExcept.h"
114 #if defined(__cplusplus)
115 // Unfortunately, boost::has_trivial_copy<T> is broken in libc++ due to its
116 // usage of __has_trivial_copy(), so we can't use it as a
117 // least-common-denominator for C++11 implementations that don't support
118 // std::is_trivially_copyable<T>.
120 // http://stackoverflow.com/questions/12754886/has-trivial-copy-behaves-differently-in-clang-and-gcc-whos-right
122 // As a result, use std::is_trivially_copyable() where it exists, and fall back
123 // to Boost otherwise.
124 #if FOLLY_HAVE_STD__IS_TRIVIALLY_COPYABLE
125 #include <type_traits>
126 #define FOLLY_IS_TRIVIALLY_COPYABLE(T) (std::is_trivially_copyable<T>::value)
128 #include <boost/type_traits.hpp>
129 #define FOLLY_IS_TRIVIALLY_COPYABLE(T) (boost::has_trivial_copy<T>::value)
131 #endif // __cplusplus
133 #endif // FOLLY_PORTABILITY_H_