ax_gcc_func_attribute.m4 revision 1.1.1.1 
1# ===========================================================================
2#  https://www.gnu.org/software/autoconf-archive/ax_gcc_func_attribute.html
3# ===========================================================================
4#
5# SYNOPSIS
6#
7#   AX_GCC_FUNC_ATTRIBUTE(ATTRIBUTE)
8#
9# DESCRIPTION
10#
11#   This macro checks if the compiler supports one of GCC's function
12#   attributes; many other compilers also provide function attributes with
13#   the same syntax. Compiler warnings are used to detect supported
14#   attributes as unsupported ones are ignored by default so quieting
15#   warnings when using this macro will yield false positives.
16#
17#   The ATTRIBUTE parameter holds the name of the attribute to be checked.
18#
19#   If ATTRIBUTE is supported define HAVE_FUNC_ATTRIBUTE_<ATTRIBUTE>.
20#
21#   The macro caches its result in the ax_cv_have_func_attribute_<attribute>
22#   variable.
23#
24#   The macro currently supports the following function attributes:
25#
26#    alias
27#    aligned
28#    alloc_size
29#    always_inline
30#    artificial
31#    cold
32#    const
33#    constructor
34#    constructor_priority for constructor attribute with priority
35#    deprecated
36#    destructor
37#    dllexport
38#    dllimport
39#    error
40#    externally_visible
41#    fallthrough
42#    flatten
43#    format
44#    format_arg
45#    gnu_format
46#    gnu_inline
47#    hot
48#    ifunc
49#    leaf
50#    malloc
51#    noclone
52#    noinline
53#    nonnull
54#    noreturn
55#    nothrow
56#    optimize
57#    pure
58#    sentinel
59#    sentinel_position
60#    unused
61#    used
62#    visibility
63#    warning
64#    warn_unused_result
65#    weak
66#    weakref
67#
68#   Unsupported function attributes will be tested with a prototype
69#   returning an int and not accepting any arguments and the result of the
70#   check might be wrong or meaningless so use with care.
71#
72# LICENSE
73#
74#   Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com>
75#
76#   Copying and distribution of this file, with or without modification, are
77#   permitted in any medium without royalty provided the copyright notice
78#   and this notice are preserved.  This file is offered as-is, without any
79#   warranty.
80
81#serial 10
82
83AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
84    AS_VAR_PUSHDEF([ac_var], [ax_cv_have_func_attribute_$1])
85
86    AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [
87        AC_LINK_IFELSE([AC_LANG_PROGRAM([
88            m4_case([$1],
89                [alias], [
90                    int foo( void ) { return 0; }
91                    int bar( void ) __attribute__(($1("foo")));
92                ],
93                [aligned], [
94                    int foo( void ) __attribute__(($1(32)));
95                ],
96                [alloc_size], [
97                    void *foo(int a) __attribute__(($1(1)));
98                ],
99                [always_inline], [
100                    inline __attribute__(($1)) int foo( void ) { return 0; }
101                ],
102                [artificial], [
103                    inline __attribute__(($1)) int foo( void ) { return 0; }
104                ],
105                [cold], [
106                    int foo( void ) __attribute__(($1));
107                ],
108                [const], [
109                    int foo( void ) __attribute__(($1));
110                ],
111                [constructor_priority], [
112                    int foo( void ) __attribute__((__constructor__(65535/2)));
113                ],
114                [constructor], [
115                    int foo( void ) __attribute__(($1));
116                ],
117                [deprecated], [
118                    int foo( void ) __attribute__(($1("")));
119                ],
120                [destructor], [
121                    int foo( void ) __attribute__(($1));
122                ],
123                [dllexport], [
124                    __attribute__(($1)) int foo( void ) { return 0; }
125                ],
126                [dllimport], [
127                    int foo( void ) __attribute__(($1));
128                ],
129                [error], [
130                    int foo( void ) __attribute__(($1("")));
131                ],
132                [externally_visible], [
133                    int foo( void ) __attribute__(($1));
134                ],
135                [fallthrough], [
136                    int foo( void ) {switch (0) { case 1: __attribute__(($1)); case 2: break ; }};
137                ],
138                [flatten], [
139                    int foo( void ) __attribute__(($1));
140                ],
141                [format], [
142                    int foo(const char *p, ...) __attribute__(($1(printf, 1, 2)));
143                ],
144                [gnu_format], [
145                    int foo(const char *p, ...) __attribute__((format(gnu_printf, 1, 2)));
146                ],
147                [format_arg], [
148                    char *foo(const char *p) __attribute__(($1(1)));
149                ],
150                [gnu_inline], [
151                    inline __attribute__(($1)) int foo( void ) { return 0; }
152                ],
153                [hot], [
154                    int foo( void ) __attribute__(($1));
155                ],
156                [ifunc], [
157                    int my_foo( void ) { return 0; }
158                    static int (*resolve_foo(void))(void) { return my_foo; }
159                    int foo( void ) __attribute__(($1("resolve_foo")));
160                ],
161                [leaf], [
162                    __attribute__(($1)) int foo( void ) { return 0; }
163                ],
164                [malloc], [
165                    void *foo( void ) __attribute__(($1));
166                ],
167                [noclone], [
168                    int foo( void ) __attribute__(($1));
169                ],
170                [noinline], [
171                    __attribute__(($1)) int foo( void ) { return 0; }
172                ],
173                [nonnull], [
174                    int foo(char *p) __attribute__(($1(1)));
175                ],
176                [noreturn], [
177                    void foo( void ) __attribute__(($1));
178                ],
179                [nothrow], [
180                    int foo( void ) __attribute__(($1));
181                ],
182                [optimize], [
183                    __attribute__(($1(3))) int foo( void ) { return 0; }
184                ],
185                [pure], [
186                    int foo( void ) __attribute__(($1));
187                ],
188                [sentinel], [
189                    int foo(void *p, ...) __attribute__(($1));
190                ],
191                [sentinel_position], [
192                    int foo(void *p, ...) __attribute__(($1(1)));
193                ],
194                [returns_nonnull], [
195                    void *foo( void ) __attribute__(($1));
196                ],
197                [unused], [
198                    int foo( void ) __attribute__(($1));
199                ],
200                [used], [
201                    int foo( void ) __attribute__(($1));
202                ],
203                [visibility], [
204                    int foo_def( void ) __attribute__(($1("default")));
205                    int foo_hid( void ) __attribute__(($1("hidden")));
206                    int foo_int( void ) __attribute__(($1("internal")));
207                    int foo_pro( void ) __attribute__(($1("protected")));
208                ],
209                [warning], [
210                    int foo( void ) __attribute__(($1("")));
211                ],
212                [warn_unused_result], [
213                    int foo( void ) __attribute__(($1));
214                ],
215                [weak], [
216                    int foo( void ) __attribute__(($1));
217                ],
218                [weakref], [
219                    static int foo( void ) { return 0; }
220                    static int bar( void ) __attribute__(($1("foo")));
221                ],
222                [
223                 m4_warn([syntax], [Unsupported attribute $1, the test may fail])
224                 int foo( void ) __attribute__(($1));
225                ]
226            )], [])
227            ],
228            dnl GCC doesn't exit with an error if an unknown attribute is
229            dnl provided but only outputs a warning, so accept the attribute
230            dnl only if no warning were issued.
231            [AS_IF([test -s conftest.err],
232                [AS_VAR_SET([ac_var], [no])],
233                [AS_VAR_SET([ac_var], [yes])])],
234            [AS_VAR_SET([ac_var], [no])])
235    ])
236
237    AS_IF([test yes = AS_VAR_GET([ac_var])],
238        [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_FUNC_ATTRIBUTE_$1), 1,
239            [Define to 1 if the system has the `$1' function attribute])], [])
240
241    AS_VAR_POPDEF([ac_var])
242])
243