# =========================================================================== # https://www.gnu.org/software/autoconf-archive/ax_gcc_func_attribute.html # =========================================================================== # # SYNOPSIS # # AX_GCC_FUNC_ATTRIBUTE(ATTRIBUTE) # # DESCRIPTION # # This macro checks if the compiler supports one of GCC's function # attributes; many other compilers also provide function attributes with # the same syntax. Compiler warnings are used to detect supported # attributes as unsupported ones are ignored by default so quieting # warnings when using this macro will yield false positives. # # The ATTRIBUTE parameter holds the name of the attribute to be checked. # # If ATTRIBUTE is supported define HAVE_FUNC_ATTRIBUTE_<ATTRIBUTE>. # # The macro caches its result in the ax_cv_have_func_attribute_<attribute> # variable. # # The macro currently supports the following function attributes: # # alias # aligned # alloc_size # always_inline # artificial # cold # const # constructor # constructor_priority for constructor attribute with priority # deprecated # destructor # dllexport # dllimport # error # externally_visible # fallthrough # flatten # format # format_arg # gnu_format # gnu_inline # hot # ifunc # leaf # malloc # noclone # noinline # nonnull # noreturn # nothrow # optimize # pure # sentinel # sentinel_position # unused # used # visibility # warning # warn_unused_result # weak # weakref # # Unsupported function attributes will be tested with a prototype # returning an int and not accepting any arguments and the result of the # check might be wrong or meaningless so use with care. # # LICENSE # # Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com> # # Copying and distribution of this file, with or without modification, are # permitted in any medium without royalty provided the copyright notice # and this notice are preserved. This file is offered as-is, without any # warranty.
AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [
AC_LINK_IFELSE([AC_LANG_PROGRAM([
m4_case([$1],
[alias], [
int foo( void ) { return 0; }
int bar( void ) __attribute__(($1("foo")));
],
[aligned], [
int foo( void ) __attribute__(($1(32)));
],
[alloc_size], [
void *foo(int a) __attribute__(($1(1)));
],
[always_inline], [
inline __attribute__(($1)) int foo( void ) { return 0; }
],
[artificial], [
inline __attribute__(($1)) int foo( void ) { return 0; }
],
[cold], [
int foo( void ) __attribute__(($1));
],
[const], [
int foo( void ) __attribute__(($1));
],
[constructor_priority], [
int foo( void ) __attribute__((__constructor__(65535/2)));
],
[constructor], [
int foo( void ) __attribute__(($1));
],
[deprecated], [
int foo( void ) __attribute__(($1("")));
],
[destructor], [
int foo( void ) __attribute__(($1));
],
[dllexport], [
__attribute__(($1)) int foo( void ) { return 0; }
],
[dllimport], [
int foo( void ) __attribute__(($1));
],
[error], [
int foo( void ) __attribute__(($1("")));
],
[externally_visible], [
int foo( void ) __attribute__(($1));
],
[fallthrough], [
void foo( int x ) {switch (x) { case 1: __attribute__(($1)); case 2: break ; }};
],
[flatten], [
int foo( void ) __attribute__(($1));
],
[format], [
int foo(const char *p, ...) __attribute__(($1(printf, 1, 2)));
],
[gnu_format], [
int foo(const char *p, ...) __attribute__((format(gnu_printf, 1, 2)));
],
[format_arg], [
char *foo(const char *p) __attribute__(($1(1)));
],
[gnu_inline], [
inline __attribute__(($1)) int foo( void ) { return 0; }
],
[hot], [
int foo( void ) __attribute__(($1));
],
[ifunc], [
int my_foo( void ) { return 0; }
static int (*resolve_foo(void))(void) { return my_foo; }
int foo( void ) __attribute__(($1("resolve_foo")));
],
[leaf], [
__attribute__(($1)) int foo( void ) { return 0; }
],
[malloc], [
void *foo( void ) __attribute__(($1));
],
[noclone], [
int foo( void ) __attribute__(($1));
],
[noinline], [
__attribute__(($1)) int foo( void ) { return 0; }
],
[nonnull], [
int foo(char *p) __attribute__(($1(1)));
],
[noreturn], [
void foo( void ) __attribute__(($1));
],
[nothrow], [
int foo( void ) __attribute__(($1));
],
[optimize], [
__attribute__(($1(3))) int foo( void ) { return 0; }
],
[pure], [
int foo( void ) __attribute__(($1));
],
[sentinel], [
int foo(void *p, ...) __attribute__(($1));
],
[sentinel_position], [
int foo(void *p, ...) __attribute__(($1(1)));
],
[returns_nonnull], [
void *foo( void ) __attribute__(($1));
],
[unused], [
int foo( void ) __attribute__(($1));
],
[used], [
int foo( void ) __attribute__(($1));
],
[visibility], [
int foo_def( void ) __attribute__(($1("default")));
int foo_hid( void ) __attribute__(($1("hidden")));
int foo_int( void ) __attribute__(($1("internal")));
int foo_pro( void ) __attribute__(($1("protected")));
],
[warning], [
int foo( void ) __attribute__(($1("")));
],
[warn_unused_result], [
int foo( void ) __attribute__(($1));
],
[weak], [
int foo( void ) __attribute__(($1));
],
[weakref], [
static int foo( void ) { return 0; }
static int bar( void ) __attribute__(($1("foo")));
],
[
m4_warn([syntax], [Unsupported attribute $1, the test may fail])
int foo( void ) __attribute__(($1));
]
)], [])
],
dnl GCC doesn't exit with an error if an unknown attribute is
dnl provided but only outputs a warning, so accept the attribute
dnl only if no warning were issued.
[AS_IF([grep -- -Wattributes conftest.err],
[AS_VAR_SET([ac_var], [no])],
[AS_VAR_SET([ac_var], [yes])])],
[AS_VAR_SET([ac_var], [no])])
])
AS_IF([test yes = AS_VAR_GET([ac_var])],
[AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_FUNC_ATTRIBUTE_$1), 1,
[Define to 1 if the system has the `$1' function attribute])], [])
AS_VAR_POPDEF([ac_var])
])
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