# wm_cflags_check.m4 - Macros to check options for the compiler into CFLAGS
#
# Copyright (c) 2013 Christophe CURIS
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.


# WM_CFLAGS_CHECK_FIRST
# ---------------------
#
# For each option provided, check which one is supported and stops when
# found, adding it to CFLAGS. It extends AX_CFLAGS_GCC_OPTION which does
# not checks for fallbacks; as a bonus it uses a shared function to
# produce smaller configure script.
#
# Usage: WM_CFLAGS_CHECK_FIRST([message], [option alt_option...])
#   $1 message: required, message displayed in 'Checking for...'
#   $2 option_list: list of options, tested in given order
#
# The first option that works is added to CFLAGS
AC_DEFUN([WM_CFLAGS_CHECK_FIRST],
[AC_REQUIRE([_WM_SHELLFN_CHKCFLAGS])
m4_define([_wm_optlist], m4_split([$2]))dnl
AS_VAR_PUSHDEF([VAR], [wm_cv_c_check_compopt[]m4_car(_wm_optlist)])dnl
m4_define([_wm_trimmed_optlist], m4_join([ ], _wm_optlist))dnl
AC_CACHE_CHECK([CFLAGS for m4_ifnblank($1,$1,m4_car(_wm_optlist))], VAR,
  [VAR="no, unknown"
   for wm_option in _wm_trimmed_optlist ; do
     AS_IF([wm_fn_c_try_compile_cflag "$wm_option"],
           [VAR="$wm_option" ; break])
   done])
AS_CASE([$VAR],
  [no,*], [],
  [AS_IF([echo " $CFLAGS " | grep " $VAR " 2>&1 > /dev/null],
    [AC_MSG_WARN([option $VAR already present in \$CFLAGS, not appended])],
    [CFLAGS="$CFLAGS $VAR"]) ])
AS_VAR_POPDEF([VAR])dnl
m4_undefine([_wm_optlist])dnl
m4_undefine([_wm_trimmed_optlist])dnl
])


# _WM_SHELLFN_CHKCFLAGS
# ---------------------
# (internal shell function)
#
# Create a shell function that tries compiling a simple program with the
# specified compiler option. Assumes the current compilation language is
# already set to C
AC_DEFUN_ONCE([_WM_SHELLFN_CHKCFLAGS],
[@%:@ wm_fn_c_try_compile_cflag CC_OPTION
@%:@ -----------------------------------
@%:@ Try compiling a function using CC_OPTION in the compiler's options
wm_fn_c_try_compile_cflag ()
{
  wm_save_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS -Werror $[]1"
  AC_COMPILE_IFELSE(
    [AC_LANG_PROGRAM([], [])],
    [wm_retval=0],
    [wm_retval=1])
  CFLAGS="$wm_save_CFLAGS"
  AS_SET_STATUS([$wm_retval])
}
])