kmod/m4/attributes.m4

# SPDX-License-Identifier: GPL-2.0-or-later WITH Autoconf-exception-macro
#
# Copyright (c) 2006-2008 Diego Pettenò <flameeyes@gmail.com>
# Copyright (c) 2006-2008 xine project
# Copyright (c) 2012 Lucas De Marchi <lucas.de.marchi@gmail.com>

AC_DEFUN([CC_CHECK_FLAG_APPEND], [
  AC_CACHE_CHECK([if $CC supports flag $3 in envvar $2],
                 AS_TR_SH([cc_cv_$2_$3]),
                 [eval "AS_TR_SH([cc_save_$2])='${$2}'"
                  eval "AS_TR_SH([$2])='-Werror `echo "$3" | sed 's/^-Wno-/-W/'`'"
                  AC_LINK_IFELSE([AC_LANG_SOURCE([int main(void) { return 0; } ])],
                          [eval "AS_TR_SH([cc_cv_$2_$3])='yes'"],
                          [eval "AS_TR_SH([cc_cv_$2_$3])='no'"])
                  eval "AS_TR_SH([$2])='$cc_save_$2'"])

  AS_IF([eval test x$]AS_TR_SH([cc_cv_$2_$3])[ = xyes],
        [eval "$1='${$1} $3'"])
])

dnl CC_CHECK_FLAGS_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG1 FLAG2])
AC_DEFUN([CC_CHECK_FLAGS_APPEND], [
  for flag in $3; do
    CC_CHECK_FLAG_APPEND($1, $2, $flag)
  done
])

dnl Check if the flag is supported by linker (cacheable)
dnl CC_CHECK_LDFLAGS([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])


dnl Check if the flag is supported by linker
dnl CC_CHECK_LDFLAGS_SILENT([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])
AC_DEFUN([CC_CHECK_LDFLAGS_SILENT], [
  AC_CACHE_VAL(AS_TR_SH([cc_cv_ldflags_$1]),
    [ac_save_LDFLAGS="$LDFLAGS"
     LDFLAGS="$LDFLAGS $1"
     AC_LINK_IFELSE([AC_LANG_SOURCE([int main() { return 1; }])],
       [eval "AS_TR_SH([cc_cv_ldflags_$1])='yes'"],
       [eval "AS_TR_SH([cc_cv_ldflags_$1])="])
     LDFLAGS="$ac_save_LDFLAGS"
    ])

  AS_IF([eval test x$]AS_TR_SH([cc_cv_ldflags_$1])[ = xyes],
    [$2], [$3])
])

dnl Check if the flag is supported by linker (cacheable)
dnl CC_CHECK_LDFLAGS([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])

AC_DEFUN([CC_CHECK_LDFLAGS], [
  AC_CACHE_CHECK([if $CC supports $1 flag],
    AS_TR_SH([cc_cv_ldflags_$1]),
    CC_CHECK_LDFLAGS_SILENT([$1]) dnl Don't execute actions here!
  )

  AS_IF([eval test x$]AS_TR_SH([cc_cv_ldflags_$1])[ = xyes],
    [$2], [$3])
])

dnl define the LDFLAGS_NOUNDEFINED variable with the correct value for
dnl the current linker to avoid undefined references in a shared object.
AC_DEFUN([CC_NOUNDEFINED], [
  dnl We check $host for which systems to enable this for.
  AC_REQUIRE([AC_CANONICAL_HOST])

  case $host in
     dnl FreeBSD (et al.) does not complete linking for shared objects when pthreads
     dnl are requested, as different implementations are present; to avoid problems
     dnl use -Wl,-z,defs only for those platform not behaving this way.
     *-freebsd* | *-openbsd*) ;;
     *)
        dnl First of all check for the --no-undefined variant of GNU ld. This allows
        dnl for a much more readable command line, so that people can understand what
        dnl it does without going to look for what the heck -z defs does.
        for possible_flags in "-Wl,--no-undefined" "-Wl,-z,defs"; do
          CC_CHECK_LDFLAGS([$possible_flags], [LDFLAGS_NOUNDEFINED="$possible_flags"])
          break
        done
        ;;
  esac

  AC_SUBST([LDFLAGS_NOUNDEFINED])
])

dnl Check for a -Werror flag or equivalent. -Werror is the GCC
dnl and ICC flag that tells the compiler to treat all the warnings
dnl as fatal. We usually need this option to make sure that some
dnl constructs (like attributes) are not simply ignored.
dnl
dnl Other compilers don't support -Werror per se, but they support
dnl an equivalent flag:
dnl  - Sun Studio compiler supports -errwarn=%all
AC_DEFUN([CC_CHECK_WERROR], [
  AC_CACHE_CHECK(
    [for $CC way to treat warnings as errors],
    [cc_cv_werror],
    [CC_CHECK_CFLAGS_SILENT([-Werror], [cc_cv_werror=-Werror],
      [CC_CHECK_CFLAGS_SILENT([-errwarn=%all], [cc_cv_werror=-errwarn=%all])])
    ])
])

AC_DEFUN([CC_CHECK_ATTRIBUTE], [
  AC_REQUIRE([CC_CHECK_WERROR])
  AC_CACHE_CHECK([if $CC supports __attribute__(( ifelse([$2], , [$1], [$2]) ))],
    AS_TR_SH([cc_cv_attribute_$1]),
    [ac_save_CFLAGS="$CFLAGS"
     CFLAGS="$CFLAGS $cc_cv_werror"
     AC_COMPILE_IFELSE([AC_LANG_SOURCE([$3])],
       [eval "AS_TR_SH([cc_cv_attribute_$1])='yes'"],
       [eval "AS_TR_SH([cc_cv_attribute_$1])='no'"])
     CFLAGS="$ac_save_CFLAGS"
    ])

  AS_IF([eval test x$]AS_TR_SH([cc_cv_attribute_$1])[ = xyes],
    [AC_DEFINE(
       AS_TR_CPP([SUPPORT_ATTRIBUTE_$1]), 1,
         [Define this if the compiler supports __attribute__(( ifelse([$2], , [$1], [$2]) ))]
         )
     $4],
    [$5])
])

AC_DEFUN([CC_ATTRIBUTE_CONSTRUCTOR], [
  CC_CHECK_ATTRIBUTE(
    [constructor],,
    [void __attribute__((constructor)) ctor() { int a; }],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_FORMAT], [
  CC_CHECK_ATTRIBUTE(
    [format], [format(printf, n, n)],
    [void __attribute__((format(printf, 1, 2))) printflike(const char *fmt, ...) { fmt = (void *)0; }],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_FORMAT_ARG], [
  CC_CHECK_ATTRIBUTE(
    [format_arg], [format_arg(printf)],
    [char *__attribute__((format_arg(1))) gettextlike(const char *fmt) { fmt = (void *)0; }],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_VISIBILITY], [
  CC_CHECK_ATTRIBUTE(
    [visibility_$1], [visibility("$1")],
    [void __attribute__((visibility("$1"))) $1_function() { }],
    [$2], [$3])
])

AC_DEFUN([CC_ATTRIBUTE_NONNULL], [
  CC_CHECK_ATTRIBUTE(
    [nonnull], [nonnull()],
    [void __attribute__((nonnull())) some_function(void *foo, void *bar) { foo = (void*)0; bar = (void*)0; }],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_UNUSED], [
  CC_CHECK_ATTRIBUTE(
    [unused], ,
    [void some_function(void *foo, __attribute__((unused)) void *bar);],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_SENTINEL], [
  CC_CHECK_ATTRIBUTE(
    [sentinel], ,
    [void some_function(void *foo, ...) __attribute__((sentinel));],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_DEPRECATED], [
  CC_CHECK_ATTRIBUTE(
    [deprecated], ,
    [void some_function(void *foo, ...) __attribute__((deprecated));],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_ALIAS], [
  CC_CHECK_ATTRIBUTE(
    [alias], [weak, alias],
    [void other_function(void *foo) { }
     void some_function(void *foo) __attribute__((weak, alias("other_function")));],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_MALLOC], [
  CC_CHECK_ATTRIBUTE(
    [malloc], ,
    [void * __attribute__((malloc)) my_alloc(int n);],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_PACKED], [
  CC_CHECK_ATTRIBUTE(
    [packed], ,
    [struct astructure { char a; int b; long c; void *d; } __attribute__((packed));],
    [$1], [$2])
])

AC_DEFUN([CC_ATTRIBUTE_CONST], [
  CC_CHECK_ATTRIBUTE(
    [const], ,
    [int __attribute__((const)) twopow(int n) { return 1 << n; } ],
    [$1], [$2])
])

AC_DEFUN([CC_FLAG_VISIBILITY], [
  AC_REQUIRE([CC_CHECK_WERROR])
  AC_CACHE_CHECK([if $CC supports -fvisibility=hidden],
    [cc_cv_flag_visibility],
    [cc_flag_visibility_save_CFLAGS="$CFLAGS"
     CFLAGS="$CFLAGS $cc_cv_werror"
     CC_CHECK_CFLAGS_SILENT([-fvisibility=hidden],
        cc_cv_flag_visibility='yes',
        cc_cv_flag_visibility='no')
     CFLAGS="$cc_flag_visibility_save_CFLAGS"])

  AS_IF([test "x$cc_cv_flag_visibility" = "xyes"],
    [AC_DEFINE([SUPPORT_FLAG_VISIBILITY], 1,
       [Define this if the compiler supports the -fvisibility flag])
     $1],
    [$2])
])

AC_DEFUN([CC_CHECK_FUNC_BUILTIN], [
  m4_pushdef([UPNAME], m4_translit([$1], [-a-z], [_A-Z]))
  AC_CACHE_CHECK([if compiler has $1 builtin function],
    [cc_cv_have_$1],
    [AC_LINK_IFELSE([AC_LANG_PROGRAM([], [
       m4_case([$1],
         [__builtin_clz], [$1(0)],
         [__builtin_types_compatible_p], [$1(int, int)],
         [__builtin_uaddl_overflow], [$1(0UL, 0UL, (void*)0)],
         [__builtin_uaddll_overflow], [$1(0ULL, 0ULL, (void*)0)],
         [__builtin_expect], [$1(0, 0)]
       )])],
       [cc_cv_have_$1=yes],
       [cc_cv_have_$1=no])])

  AS_IF([test "x$cc_cv_have_$1" = "xyes"],
    [AC_DEFINE([HAVE_]m4_defn([UPNAME]), 1, [Define to 1 if compiler has $1() builtin function])
     $2],
    [AS_IF([test "x$3" = "x"], [AC_MSG_ERROR([*** builtin function not found: $1()])],
           [AC_DEFINE([HAVE_]m4_defn([UPNAME]), 0)
            $3])]
  )
  m4_popdef([UPNAME])
])

AC_DEFUN([CC_ATTRIBUTE_ALIGNED], [
  AC_REQUIRE([CC_CHECK_WERROR])
  AC_CACHE_CHECK([highest __attribute__ ((aligned ())) supported],
    [cc_cv_attribute_aligned],
    [ac_save_CFLAGS="$CFLAGS"
     CFLAGS="$CFLAGS $cc_cv_werror"
     for cc_attribute_align_try in 64 32 16 8 4 2; do
        AC_COMPILE_IFELSE([AC_LANG_SOURCE([
          int main() {
            static char c __attribute__ ((aligned($cc_attribute_align_try))) = 0;
            return c;
          }])], [cc_cv_attribute_aligned=$cc_attribute_align_try; break])
     done
     CFLAGS="$ac_save_CFLAGS"
  ])

  if test "x$cc_cv_attribute_aligned" != "x"; then
     AC_DEFINE_UNQUOTED([ATTRIBUTE_ALIGNED_MAX], [$cc_cv_attribute_aligned],
       [Define the highest alignment supported])
  fi
])