FFmpeg
attributes.h
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1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * Macro definitions for various function/variable attributes
24  */
25 
26 #ifndef AVUTIL_ATTRIBUTES_H
27 #define AVUTIL_ATTRIBUTES_H
28 
29 #ifdef __GNUC__
30 # define AV_GCC_VERSION_AT_LEAST(x,y) (__GNUC__ > (x) || __GNUC__ == (x) && __GNUC_MINOR__ >= (y))
31 # define AV_GCC_VERSION_AT_MOST(x,y) (__GNUC__ < (x) || __GNUC__ == (x) && __GNUC_MINOR__ <= (y))
32 #else
33 # define AV_GCC_VERSION_AT_LEAST(x,y) 0
34 # define AV_GCC_VERSION_AT_MOST(x,y) 0
35 #endif
36 
37 #ifdef __has_builtin
38 # define AV_HAS_BUILTIN(x) __has_builtin(x)
39 #else
40 # define AV_HAS_BUILTIN(x) 0
41 #endif
42 
43 #if defined(__cplusplus) && defined(__has_cpp_attribute)
44 # define AV_HAS_STD_ATTRIBUTE(x) __has_cpp_attribute(x)
45 #elif !defined(__cplusplus) && defined(__has_c_attribute)
46 # define AV_HAS_STD_ATTRIBUTE(x) __has_c_attribute(x)
47 #else
48 # define AV_HAS_STD_ATTRIBUTE(x) 0
49 #endif
50 
51 #ifndef av_always_inline
52 #if AV_GCC_VERSION_AT_LEAST(3,1) || defined(__clang__)
53 # define av_always_inline __attribute__((always_inline)) inline
54 #elif defined(_MSC_VER)
55 # define av_always_inline __forceinline
56 #else
57 # define av_always_inline inline
58 #endif
59 #endif
60 
61 #ifndef av_extern_inline
62 #if defined(__ICL) && __ICL >= 1210 || defined(__GNUC_STDC_INLINE__)
63 # define av_extern_inline extern inline
64 #else
65 # define av_extern_inline inline
66 #endif
67 #endif
68 
69 #if AV_HAS_STD_ATTRIBUTE(nodiscard)
70 # define av_warn_unused_result [[nodiscard]]
71 #elif AV_GCC_VERSION_AT_LEAST(3,4) || defined(__clang__)
72 # define av_warn_unused_result __attribute__((warn_unused_result))
73 #else
74 # define av_warn_unused_result
75 #endif
76 
77 #if AV_GCC_VERSION_AT_LEAST(3,1) || defined(__clang__)
78 # define av_noinline __attribute__((noinline))
79 #elif defined(_MSC_VER)
80 # define av_noinline __declspec(noinline)
81 #else
82 # define av_noinline
83 #endif
84 
85 #if AV_GCC_VERSION_AT_LEAST(3,1) || defined(__clang__)
86 # define av_pure __attribute__((pure))
87 #else
88 # define av_pure
89 #endif
90 
91 #if AV_GCC_VERSION_AT_LEAST(2,6) || defined(__clang__)
92 # define av_const __attribute__((const))
93 #else
94 # define av_const
95 #endif
96 
97 #if AV_GCC_VERSION_AT_LEAST(4,3) || defined(__clang__)
98 # define av_cold __attribute__((cold))
99 #else
100 # define av_cold
101 #endif
102 
103 #if AV_GCC_VERSION_AT_LEAST(4,1) && !defined(__llvm__)
104 # define av_flatten __attribute__((flatten))
105 #else
106 # define av_flatten
107 #endif
108 
109 #if AV_HAS_STD_ATTRIBUTE(deprecated)
110 # define attribute_deprecated [[deprecated]]
111 #elif AV_GCC_VERSION_AT_LEAST(3,1) || defined(__clang__)
112 # define attribute_deprecated __attribute__((deprecated))
113 #elif defined(_MSC_VER)
114 # define attribute_deprecated __declspec(deprecated)
115 #else
116 # define attribute_deprecated
117 #endif
118 
119 /**
120  * Disable warnings about deprecated features
121  * This is useful for sections of code kept for backward compatibility and
122  * scheduled for removal.
123  */
124 #ifndef AV_NOWARN_DEPRECATED
125 #if AV_GCC_VERSION_AT_LEAST(4,6) || defined(__clang__)
126 # define AV_NOWARN_DEPRECATED(code) \
127  _Pragma("GCC diagnostic push") \
128  _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"") \
129  code \
130  _Pragma("GCC diagnostic pop")
131 #elif defined(_MSC_VER)
132 # define AV_NOWARN_DEPRECATED(code) \
133  __pragma(warning(push)) \
134  __pragma(warning(disable : 4996)) \
135  code; \
136  __pragma(warning(pop))
137 #else
138 # define AV_NOWARN_DEPRECATED(code) code
139 #endif
140 #endif
141 
142 #if AV_HAS_STD_ATTRIBUTE(maybe_unused)
143 # define av_unused [[maybe_unused]]
144 #elif defined(__GNUC__) || defined(__clang__)
145 # define av_unused __attribute__((unused))
146 #else
147 # define av_unused
148 #endif
149 
150 /**
151  * Mark a variable as used and prevent the compiler from optimizing it
152  * away. This is useful for variables accessed only from inline
153  * assembler without the compiler being aware.
154  */
155 #if AV_GCC_VERSION_AT_LEAST(3,1) || defined(__clang__)
156 # define av_used __attribute__((used))
157 #else
158 # define av_used
159 #endif
160 
161 #if AV_GCC_VERSION_AT_LEAST(3,3) || defined(__clang__)
162 # define av_alias __attribute__((may_alias))
163 #else
164 # define av_alias
165 #endif
166 
167 #if (defined(__GNUC__) || defined(__clang__)) && !defined(__INTEL_COMPILER)
168 # define av_uninit(x) x=x
169 #else
170 # define av_uninit(x) x
171 #endif
172 
173 #if defined(__GNUC__) || defined(__clang__)
174 # define av_builtin_constant_p __builtin_constant_p
175 # define av_printf_format(fmtpos, attrpos) __attribute__((__format__(__printf__, fmtpos, attrpos)))
176 # define av_scanf_format(fmtpos, attrpos) __attribute__((__format__(__scanf__, fmtpos, attrpos)))
177 #else
178 # define av_builtin_constant_p(x) 0
179 # define av_printf_format(fmtpos, attrpos)
180 # define av_scanf_format(fmtpos, attrpos)
181 #endif
182 
183 #if AV_HAS_STD_ATTRIBUTE(noreturn)
184 # define av_noreturn [[noreturn]]
185 #elif AV_GCC_VERSION_AT_LEAST(2,5) || defined(__clang__)
186 # define av_noreturn __attribute__((noreturn))
187 #else
188 # define av_noreturn
189 #endif
190 
191 #endif /* AVUTIL_ATTRIBUTES_H */