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
55 # define FOLLY_NOINLINE __declspec(noinline)
56 #elif defined(__clang__) || defined(__GNUC__)
57 # define FOLLY_NOINLINE __attribute__((noinline))
59 # define FOLLY_NOINLINE
64 # define FOLLY_ALWAYS_INLINE __forceinline
65 #elif defined(__clang__) || defined(__GNUC__)
66 # define FOLLY_ALWAYS_INLINE inline __attribute__((always_inline))
68 # define FOLLY_ALWAYS_INLINE
71 // portable version check
73 # if defined __GNUC__ && defined __GNUC_MINOR__
74 # define __GNUC_PREREQ(maj, min) ((__GNUC__ << 16) + __GNUC_MINOR__ >= \
75 ((maj) << 16) + (min))
77 # define __GNUC_PREREQ(maj, min) 0
82 /* Define macro wrappers for C++11's "final" and "override" keywords, which
83 * are supported in gcc 4.7 but not gcc 4.6. */
84 #if !defined(FOLLY_FINAL) && !defined(FOLLY_OVERRIDE)
85 # if defined(__clang__) || __GNUC_PREREQ(4, 7)
86 # define FOLLY_FINAL final
87 # define FOLLY_OVERRIDE override
89 # define FOLLY_FINAL /**/
90 # define FOLLY_OVERRIDE /**/
95 // Define to 1 if you have the `preadv' and `pwritev' functions, respectively
96 #if !defined(FOLLY_HAVE_PREADV) && !defined(FOLLY_HAVE_PWRITEV)
97 # if defined(__GLIBC_PREREQ)
98 # if __GLIBC_PREREQ(2, 10)
99 # define FOLLY_HAVE_PREADV 1
100 # define FOLLY_HAVE_PWRITEV 1
105 // It turns out that GNU libstdc++ and LLVM libc++ differ on how they implement
106 // the 'std' namespace; the latter uses inline namepsaces. Wrap this decision
107 // up in a macro to make forward-declarations easier.
109 #define FOLLY_NAMESPACE_STD_BEGIN _LIBCPP_BEGIN_NAMESPACE_STD
110 #define FOLLY_NAMESPACE_STD_END _LIBCPP_END_NAMESPACE_STD
112 #define FOLLY_NAMESPACE_STD_BEGIN namespace std {
113 #define FOLLY_NAMESPACE_STD_END }
116 // Some platforms lack clock_gettime(2) and clock_getres(2). Inject our own
117 // versions of these into the global namespace.
118 #if FOLLY_HAVE_CLOCK_GETTIME
121 #include "folly/detail/Clock.h"
124 // Provide our own std::__throw_* wrappers for platforms that don't have them
125 #if FOLLY_HAVE_BITS_FUNCTEXCEPT_H
126 #include <bits/functexcept.h>
128 #include "folly/detail/FunctionalExcept.h"
131 #if defined(__cplusplus)
132 // Unfortunately, boost::has_trivial_copy<T> is broken in libc++ due to its
133 // usage of __has_trivial_copy(), so we can't use it as a
134 // least-common-denominator for C++11 implementations that don't support
135 // std::is_trivially_copyable<T>.
137 // http://stackoverflow.com/questions/12754886/has-trivial-copy-behaves-differently-in-clang-and-gcc-whos-right
139 // As a result, use std::is_trivially_copyable() where it exists, and fall back
140 // to Boost otherwise.
141 #if FOLLY_HAVE_STD__IS_TRIVIALLY_COPYABLE
142 #include <type_traits>
143 #define FOLLY_IS_TRIVIALLY_COPYABLE(T) \
144 (std::is_trivially_copyable<T>::value)
146 #include <boost/type_traits.hpp>
147 #define FOLLY_IS_TRIVIALLY_COPYABLE(T) \
148 (boost::has_trivial_copy<T>::value && \
149 boost::has_trivial_destructor<T>::value)
151 #endif // __cplusplus
153 #endif // FOLLY_PORTABILITY_H_