1 # ===========================================================================
2 # http://www.gnu.org/software/autoconf-archive/ax_gcc_func_attribute.html
3 # ===========================================================================
7 # AX_GCC_FUNC_ATTRIBUTE(ATTRIBUTE)
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.
17 # The ATTRIBUTE parameter holds the name of the attribute to be checked.
19 # If ATTRIBUTE is supported define HAVE_FUNC_ATTRIBUTE_<ATTRIBUTE>.
21 # The macro caches its result in the ax_cv_have_func_attribute_<attribute>
24 # The macro currently supports the following function attributes:
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.
70 # Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com>
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
79 AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
80 AS_VAR_PUSHDEF([ac_var], [ax_cv_have_func_attribute_$1])
82 AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [
83 AC_LINK_IFELSE([AC_LANG_PROGRAM([
86 int foo( void ) { return 0; }
87 int bar( void ) __attribute__(($1("foo")));
90 int foo( void ) __attribute__(($1(32)));
93 void *foo(int a) __attribute__(($1(1)));
96 inline __attribute__(($1)) int foo( void ) { return 0; }
99 inline __attribute__(($1)) int foo( void ) { return 0; }
102 int foo( void ) __attribute__(($1));
105 int foo( void ) __attribute__(($1));
108 int foo( void ) __attribute__(($1));
111 int foo( void ) __attribute__(($1("")));
114 int foo( void ) __attribute__(($1));
117 __attribute__(($1)) int foo( void ) { return 0; }
120 int foo( void ) __attribute__(($1));
123 int foo( void ) __attribute__(($1("")));
125 [externally_visible], [
126 int foo( void ) __attribute__(($1));
129 int foo( void ) __attribute__(($1));
132 int foo(const char *p, ...) __attribute__(($1(printf, 1, 2)));
135 char *foo(const char *p) __attribute__(($1(1)));
138 inline __attribute__(($1)) int foo( void ) { return 0; }
141 int foo( void ) __attribute__(($1));
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")));
149 __attribute__(($1)) int foo( void ) { return 0; }
152 void *foo( void ) __attribute__(($1));
155 int foo( void ) __attribute__(($1));
158 __attribute__(($1)) int foo( void ) { return 0; }
161 int foo(char *p) __attribute__(($1(1)));
164 void foo( void ) __attribute__(($1));
167 int foo( void ) __attribute__(($1));
170 __attribute__(($1(3))) int foo( void ) { return 0; }
173 struct __attribute__(($1)) foo { int bar; };
176 int foo( void ) __attribute__(($1));
179 int foo( void ) __attribute__(($1));
182 int foo( void ) __attribute__(($1));
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")));
191 int foo( void ) __attribute__(($1("")));
193 [warn_unused_result], [
194 int foo( void ) __attribute__(($1));
197 int foo( void ) __attribute__(($1));
200 static int foo( void ) { return 0; }
201 static int bar( void ) __attribute__(($1("foo")));
204 m4_warn([syntax], [Unsupported attribute $1, the test may fail])
205 int foo( void ) __attribute__(($1));
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])])
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])], [])
222 AS_VAR_POPDEF([ac_var])