m4/ax_gcc_func_attribute.m4

   1 # ===========================================================================
   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 #    returns_nonnull
  57 #    unused
  58 #    used
  59 #    visibility
  60 #    warning
  61 #    warn_unused_result
  62 #    weak
  63 #    weakref
  64 #
  65 #   Unsuppored function attributes will be tested with a prototype returning
  66 #   an int and not accepting any arguments and the result of the check might
  67 #   be wrong or meaningless so use with care.
  68 #
  69 # LICENSE
  70 #
  71 #   Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com>
  72 #
  73 #   Copying and distribution of this file, with or without modification, are
  74 #   permitted in any medium without royalty provided the copyright notice
  75 #   and this notice are preserved.  This file is offered as-is, without any
  76 #   warranty.
  77
  78 #serial 2
  79
  80 # mattst88:
  81 #     Added support for returns_nonnull attribute
  82
  83 AC_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], [
 112                     int foo( void ) __attribute__(($1));
 113                 ],
 114                 [deprecated], [
 115                     int foo( void ) __attribute__(($1("")));
 116                 ],
 117                 [destructor], [
 118                     int foo( void ) __attribute__(($1));
 119                 ],
 120                 [dllexport], [
 121                     __attribute__(($1)) int foo( void ) { return 0; }
 122                 ],
 123                 [dllimport], [
 124                     int foo( void ) __attribute__(($1));
 125                 ],
 126                 [error], [
 127                     int foo( void ) __attribute__(($1("")));
 128                 ],
 129                 [externally_visible], [
 130                     int foo( void ) __attribute__(($1));
 131                 ],
 132                 [flatten], [
 133                     int foo( void ) __attribute__(($1));
 134                 ],
 135                 [format], [
 136                     int foo(const char *p, ...) __attribute__(($1(printf, 1, 2)));
 137                 ],
 138                 [format_arg], [
 139                     char *foo(const char *p) __attribute__(($1(1)));
 140                 ],
 141                 [gnu_inline], [
 142                     inline __attribute__(($1)) int foo( void ) { return 0; }
 143                 ],
 144                 [hot], [
 145                     int foo( void ) __attribute__(($1));
 146                 ],
 147                 [ifunc], [
 148                     int my_foo( void ) { return 0; }
 149                     static int (*resolve_foo(void))(void) { return my_foo; }
 150                     int foo( void ) __attribute__(($1("resolve_foo")));
 151                 ],
 152                 [leaf], [
 153                     __attribute__(($1)) int foo( void ) { return 0; }
 154                 ],
 155                 [malloc], [
 156                     void *foo( void ) __attribute__(($1));
 157                 ],
 158                 [noclone], [
 159                     int foo( void ) __attribute__(($1));
 160                 ],
 161                 [noinline], [
 162                     __attribute__(($1)) int foo( void ) { return 0; }
 163                 ],
 164                 [nonnull], [
 165                     int foo(char *p) __attribute__(($1(1)));
 166                 ],
 167                 [noreturn], [
 168                     void foo( void ) __attribute__(($1));
 169                 ],
 170                 [nothrow], [
 171                     int foo( void ) __attribute__(($1));
 172                 ],
 173                 [optimize], [
 174                     __attribute__(($1(3))) int foo( void ) { return 0; }
 175                 ],
 176                 [packed], [
 177                     struct __attribute__(($1)) foo { int bar; };
 178                 ],
 179                 [pure], [
 180                     int foo( void ) __attribute__(($1));
 181                 ],
 182                 [returns_nonnull], [
 183                     int *foo( void ) __attribute__(($1));
 184                 ],
 185                 [unused], [
 186                     int foo( void ) __attribute__(($1));
 187                 ],
 188                 [used], [
 189                     int foo( void ) __attribute__(($1));
 190                 ],
 191                 [visibility], [
 192                     int foo_def( void ) __attribute__(($1("default")));
 193                     int foo_hid( void ) __attribute__(($1("hidden")));
 194                     int foo_int( void ) __attribute__(($1("internal")));
 195                     int foo_pro( void ) __attribute__(($1("protected")));
 196                 ],
 197                 [warning], [
 198                     int foo( void ) __attribute__(($1("")));
 199                 ],
 200                 [warn_unused_result], [
 201                     int foo( void ) __attribute__(($1));
 202                 ],
 203                 [weak], [
 204                     int foo( void ) __attribute__(($1));
 205                 ],
 206                 [weakref], [
 207                     static int foo( void ) { return 0; }
 208                     static int bar( void ) __attribute__(($1("foo")));
 209                 ],
 210                 [
 211                  m4_warn([syntax], [Unsupported attribute $1, the test may fail])
 212                  int foo( void ) __attribute__(($1));
 213                 ]
 214             )], [])
 215             ],
 216             dnl GCC doesn't exit with an error if an unknown attribute is
 217             dnl provided but only outputs a warning, so accept the attribute
 218             dnl only if no warning were issued.
 219             [AS_IF([test -s conftest.err],
 220                 [AS_VAR_SET([ac_var], [no])],
 221                 [AS_VAR_SET([ac_var], [yes])])],
 222             [AS_VAR_SET([ac_var], [no])])
 223     ])
 224
 225     AS_IF([test yes = AS_VAR_GET([ac_var])],
 226         [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_FUNC_ATTRIBUTE_$1), 1,
 227             [Define to 1 if the system has the `$1' function attribute])], [])
 228
 229     AS_VAR_POPDEF([ac_var])
 230 ])