1 # SPDX-License-Identifier: FSFAP 2 # 3 # =========================================================================== 4 # https://www.gnu.org/software/autoconf-archive/ax_gcc_func_attribute.html 5 # =========================================================================== 6 # 7 # SYNOPSIS 8 # 9 # AX_GCC_FUNC_ATTRIBUTE(ATTRIBUTE) 10 # 11 # DESCRIPTION 12 # 13 # This macro checks if the compiler supports one of GCC's function 14 # attributes; many other compilers also provide function attributes with 15 # the same syntax. Compiler warnings are used to detect supported 16 # attributes as unsupported ones are ignored by default so quieting 17 # warnings when using this macro will yield false positives. 18 # 19 # The ATTRIBUTE parameter holds the name of the attribute to be checked. 20 # 21 # If ATTRIBUTE is supported define HAVE_FUNC_ATTRIBUTE_<ATTRIBUTE>. 22 # 23 # The macro caches its result in the ax_cv_have_func_attribute_<attribute> 24 # variable. 25 # 26 # The macro currently supports the following function attributes: 27 # 28 # alias 29 # aligned 30 # alloc_size 31 # always_inline 32 # artificial 33 # cold 34 # const 35 # constructor 36 # constructor_priority for constructor attribute with priority 37 # deprecated 38 # destructor 39 # dllexport 40 # dllimport 41 # error 42 # externally_visible 43 # fallthrough 44 # flatten 45 # format 46 # format_arg 47 # gnu_format 48 # gnu_inline 49 # hot 50 # ifunc 51 # leaf 52 # malloc 53 # noclone 54 # noinline 55 # nonnull 56 # noreturn 57 # nothrow 58 # optimize 59 # pure 60 # sentinel 61 # sentinel_position 62 # unused 63 # used 64 # visibility 65 # warning 66 # warn_unused_result 67 # weak 68 # weakref 69 # 70 # Unsupported function attributes will be tested with a prototype 71 # returning an int and not accepting any arguments and the result of the 72 # check might be wrong or meaningless so use with care. 73 # 74 # LICENSE 75 # 76 # Copyright (c) 2013 Gabriele Svelto <gabriele.svelto (a] gmail.com> 77 # 78 # Copying and distribution of this file, with or without modification, are 79 # permitted in any medium without royalty provided the copyright notice 80 # and this notice are preserved. This file is offered as-is, without any 81 # warranty. 82 83 #serial 13 84 85 AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [ 86 AS_VAR_PUSHDEF([ac_var], [ax_cv_have_func_attribute_$1]) 87 88 AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [ 89 AC_LINK_IFELSE([AC_LANG_PROGRAM([ 90 m4_case([$1], 91 [alias], [ 92 int foo( void ) { return 0; } 93 int bar( void ) __attribute__(($1("foo"))); 94 ], 95 [aligned], [ 96 int foo( void ) __attribute__(($1(32))); 97 ], 98 [alloc_size], [ 99 void *foo(int a) __attribute__(($1(1))); 100 ], 101 [always_inline], [ 102 inline __attribute__(($1)) int foo( void ) { return 0; } 103 ], 104 [artificial], [ 105 inline __attribute__(($1)) int foo( void ) { return 0; } 106 ], 107 [cold], [ 108 int foo( void ) __attribute__(($1)); 109 ], 110 [const], [ 111 int foo( void ) __attribute__(($1)); 112 ], 113 [constructor_priority], [ 114 int foo( void ) __attribute__((__constructor__(65535/2))); 115 ], 116 [constructor], [ 117 int foo( void ) __attribute__(($1)); 118 ], 119 [deprecated], [ 120 int foo( void ) __attribute__(($1(""))); 121 ], 122 [destructor], [ 123 int foo( void ) __attribute__(($1)); 124 ], 125 [dllexport], [ 126 __attribute__(($1)) int foo( void ) { return 0; } 127 ], 128 [dllimport], [ 129 int foo( void ) __attribute__(($1)); 130 ], 131 [error], [ 132 int foo( void ) __attribute__(($1(""))); 133 ], 134 [externally_visible], [ 135 int foo( void ) __attribute__(($1)); 136 ], 137 [fallthrough], [ 138 void foo( int x ) {switch (x) { case 1: __attribute__(($1)); case 2: break ; }}; 139 ], 140 [flatten], [ 141 int foo( void ) __attribute__(($1)); 142 ], 143 [format], [ 144 int foo(const char *p, ...) __attribute__(($1(printf, 1, 2))); 145 ], 146 [gnu_format], [ 147 int foo(const char *p, ...) __attribute__((format(gnu_printf, 1, 2))); 148 ], 149 [format_arg], [ 150 char *foo(const char *p) __attribute__(($1(1))); 151 ], 152 [gnu_inline], [ 153 inline __attribute__(($1)) int foo( void ) { return 0; } 154 ], 155 [hot], [ 156 int foo( void ) __attribute__(($1)); 157 ], 158 [ifunc], [ 159 int my_foo( void ) { return 0; } 160 static int (*resolve_foo(void))(void) { return my_foo; } 161 int foo( void ) __attribute__(($1("resolve_foo"))); 162 ], 163 [leaf], [ 164 __attribute__(($1)) int foo( void ) { return 0; } 165 ], 166 [malloc], [ 167 void *foo( void ) __attribute__(($1)); 168 ], 169 [noclone], [ 170 int foo( void ) __attribute__(($1)); 171 ], 172 [noinline], [ 173 __attribute__(($1)) int foo( void ) { return 0; } 174 ], 175 [nonnull], [ 176 int foo(char *p) __attribute__(($1(1))); 177 ], 178 [noreturn], [ 179 void foo( void ) __attribute__(($1)); 180 ], 181 [nothrow], [ 182 int foo( void ) __attribute__(($1)); 183 ], 184 [optimize], [ 185 __attribute__(($1(3))) int foo( void ) { return 0; } 186 ], 187 [pure], [ 188 int foo( void ) __attribute__(($1)); 189 ], 190 [sentinel], [ 191 int foo(void *p, ...) __attribute__(($1)); 192 ], 193 [sentinel_position], [ 194 int foo(void *p, ...) __attribute__(($1(1))); 195 ], 196 [returns_nonnull], [ 197 void *foo( void ) __attribute__(($1)); 198 ], 199 [unused], [ 200 int foo( void ) __attribute__(($1)); 201 ], 202 [used], [ 203 int foo( void ) __attribute__(($1)); 204 ], 205 [visibility], [ 206 int foo_def( void ) __attribute__(($1("default"))); 207 int foo_hid( void ) __attribute__(($1("hidden"))); 208 int foo_int( void ) __attribute__(($1("internal"))); 209 int foo_pro( void ) __attribute__(($1("protected"))); 210 ], 211 [warning], [ 212 int foo( void ) __attribute__(($1(""))); 213 ], 214 [warn_unused_result], [ 215 int foo( void ) __attribute__(($1)); 216 ], 217 [weak], [ 218 int foo( void ) __attribute__(($1)); 219 ], 220 [weakref], [ 221 static int foo( void ) { return 0; } 222 static int bar( void ) __attribute__(($1("foo"))); 223 ], 224 [ 225 m4_warn([syntax], [Unsupported attribute $1, the test may fail]) 226 int foo( void ) __attribute__(($1)); 227 ] 228 )], []) 229 ], 230 dnl GCC doesn't exit with an error if an unknown attribute is 231 dnl provided but only outputs a warning, so accept the attribute 232 dnl only if no warning were issued. 233 [AS_IF([grep -- -Wattributes conftest.err], 234 [AS_VAR_SET([ac_var], [no])], 235 [AS_VAR_SET([ac_var], [yes])])], 236 [AS_VAR_SET([ac_var], [no])]) 237 ]) 238 239 AS_IF([test yes = AS_VAR_GET([ac_var])], 240 [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_FUNC_ATTRIBUTE_$1), 1, 241 [Define to 1 if the system has the `$1' function attribute])], []) 242 243 AS_VAR_POPDEF([ac_var]) 244 ]) 245
Indexes created Mon Mar 02 05:31:46 UTC 2026