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Matt Turner976464c2014-09-21 18:14:01 -07001# ===========================================================================
2# http://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# deprecated
35# destructor
36# dllexport
37# dllimport
38# error
39# externally_visible
40# flatten
41# format
42# format_arg
43# gnu_inline
44# hot
45# ifunc
46# leaf
47# malloc
48# noclone
49# noinline
50# nonnull
51# noreturn
52# nothrow
53# optimize
54# packed
55# pure
56# unused
57# used
58# visibility
59# warning
60# warn_unused_result
61# weak
62# weakref
63#
64# Unsuppored function attributes will be tested with a prototype returning
65# an int and not accepting any arguments and the result of the check might
66# be wrong or meaningless so use with care.
67#
68# LICENSE
69#
70# Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com>
71#
72# Copying and distribution of this file, with or without modification, are
73# permitted in any medium without royalty provided the copyright notice
74# and this notice are preserved. This file is offered as-is, without any
75# warranty.
76
77#serial 2
78
79AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
80 AS_VAR_PUSHDEF([ac_var], [ax_cv_have_func_attribute_$1])
81
82 AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [
83 AC_LINK_IFELSE([AC_LANG_PROGRAM([
84 m4_case([$1],
85 [alias], [
86 int foo( void ) { return 0; }
87 int bar( void ) __attribute__(($1("foo")));
88 ],
89 [aligned], [
90 int foo( void ) __attribute__(($1(32)));
91 ],
92 [alloc_size], [
93 void *foo(int a) __attribute__(($1(1)));
94 ],
95 [always_inline], [
96 inline __attribute__(($1)) int foo( void ) { return 0; }
97 ],
98 [artificial], [
99 inline __attribute__(($1)) int foo( void ) { return 0; }
100 ],
101 [cold], [
102 int foo( void ) __attribute__(($1));
103 ],
104 [const], [
105 int foo( void ) __attribute__(($1));
106 ],
107 [constructor], [
108 int foo( void ) __attribute__(($1));
109 ],
110 [deprecated], [
111 int foo( void ) __attribute__(($1("")));
112 ],
113 [destructor], [
114 int foo( void ) __attribute__(($1));
115 ],
116 [dllexport], [
117 __attribute__(($1)) int foo( void ) { return 0; }
118 ],
119 [dllimport], [
120 int foo( void ) __attribute__(($1));
121 ],
122 [error], [
123 int foo( void ) __attribute__(($1("")));
124 ],
125 [externally_visible], [
126 int foo( void ) __attribute__(($1));
127 ],
128 [flatten], [
129 int foo( void ) __attribute__(($1));
130 ],
131 [format], [
132 int foo(const char *p, ...) __attribute__(($1(printf, 1, 2)));
133 ],
134 [format_arg], [
135 char *foo(const char *p) __attribute__(($1(1)));
136 ],
137 [gnu_inline], [
138 inline __attribute__(($1)) int foo( void ) { return 0; }
139 ],
140 [hot], [
141 int foo( void ) __attribute__(($1));
142 ],
143 [ifunc], [
144 int my_foo( void ) { return 0; }
145 static int (*resolve_foo(void))(void) { return my_foo; }
146 int foo( void ) __attribute__(($1("resolve_foo")));
147 ],
148 [leaf], [
149 __attribute__(($1)) int foo( void ) { return 0; }
150 ],
151 [malloc], [
152 void *foo( void ) __attribute__(($1));
153 ],
154 [noclone], [
155 int foo( void ) __attribute__(($1));
156 ],
157 [noinline], [
158 __attribute__(($1)) int foo( void ) { return 0; }
159 ],
160 [nonnull], [
161 int foo(char *p) __attribute__(($1(1)));
162 ],
163 [noreturn], [
164 void foo( void ) __attribute__(($1));
165 ],
166 [nothrow], [
167 int foo( void ) __attribute__(($1));
168 ],
169 [optimize], [
170 __attribute__(($1(3))) int foo( void ) { return 0; }
171 ],
172 [packed], [
173 struct __attribute__(($1)) foo { int bar; };
174 ],
175 [pure], [
176 int foo( void ) __attribute__(($1));
177 ],
178 [unused], [
179 int foo( void ) __attribute__(($1));
180 ],
181 [used], [
182 int foo( void ) __attribute__(($1));
183 ],
184 [visibility], [
185 int foo_def( void ) __attribute__(($1("default")));
186 int foo_hid( void ) __attribute__(($1("hidden")));
187 int foo_int( void ) __attribute__(($1("internal")));
188 int foo_pro( void ) __attribute__(($1("protected")));
189 ],
190 [warning], [
191 int foo( void ) __attribute__(($1("")));
192 ],
193 [warn_unused_result], [
194 int foo( void ) __attribute__(($1));
195 ],
196 [weak], [
197 int foo( void ) __attribute__(($1));
198 ],
199 [weakref], [
200 static int foo( void ) { return 0; }
201 static int bar( void ) __attribute__(($1("foo")));
202 ],
203 [
204 m4_warn([syntax], [Unsupported attribute $1, the test may fail])
205 int foo( void ) __attribute__(($1));
206 ]
207 )], [])
208 ],
209 dnl GCC doesn't exit with an error if an unknown attribute is
210 dnl provided but only outputs a warning, so accept the attribute
211 dnl only if no warning were issued.
212 [AS_IF([test -s conftest.err],
213 [AS_VAR_SET([ac_var], [no])],
214 [AS_VAR_SET([ac_var], [yes])])],
215 [AS_VAR_SET([ac_var], [no])])
216 ])
217
218 AS_IF([test yes = AS_VAR_GET([ac_var])],
219 [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_FUNC_ATTRIBUTE_$1), 1,
220 [Define to 1 if the system has the `$1' function attribute])], [])
221
222 AS_VAR_POPDEF([ac_var])
223])