##### http://autoconf-archive.cryp.to/ax_cflags_warn_all.html
#
# SYNOPSIS
#
#   AX_CFLAGS_WARN_ALL [(shellvar [,default, [A/NA]])]
#
# DESCRIPTION
#
#   Try to find a compiler option that enables most reasonable
#   warnings. This macro is directly derived from VL_PROG_CC_WARNINGS
#   which is split up into two AX_CFLAGS_WARN_ALL and
#   AX_CFLAGS_WARN_ALL_ANSI
#
#   For the GNU CC compiler it will be -Wall (and -ansi -pedantic) The
#   result is added to the shellvar being CFLAGS by default.
#
#   Currently this macro knows about GCC, Solaris C compiler, Digital
#   Unix C compiler, C for AIX Compiler, HP-UX C compiler, IRIX C
#   compiler, NEC SX-5 (Super-UX 10) C compiler, and Cray J90 (Unicos
#   10.0.0.8) C compiler.
#
#    - $1 shell-variable-to-add-to : CFLAGS
#    - $2 add-value-if-not-found : nothing
#    - $3 action-if-found : add value to shellvariable
#    - $4 action-if-not-found : nothing
#
# LAST MODIFICATION
#
#   2006-12-12
#
# COPYLEFT
#
#   Copyright (c) 2006 Guido U. Draheim <guidod@gmx.de>
#
#   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., 59 Temple Place - Suite 330, Boston, MA
#   02111-1307, USA.
#
#   As a special exception, the respective Autoconf Macro's copyright
#   owner gives unlimited permission to copy, distribute and modify the
#   configure scripts that are the output of Autoconf when processing
#   the Macro. You need not follow the terms of the GNU General Public
#   License when using or distributing such scripts, even though
#   portions of the text of the Macro appear in them. The GNU General
#   Public License (GPL) does govern all other use of the material that
#   constitutes the Autoconf Macro.
#
#   This special exception to the GPL applies to versions of the
#   Autoconf Macro released by the Autoconf Macro Archive. When you
#   make and distribute a modified version of the Autoconf Macro, you
#   may extend this special exception to the GPL to apply to your
#   modified version as well.

AC_DEFUN([AX_CFLAGS_WARN_ALL],[dnl
AS_VAR_PUSHDEF([FLAGS],[CFLAGS])dnl
AS_VAR_PUSHDEF([VAR],[ac_cv_cflags_warn_all])dnl
AC_CACHE_CHECK([m4_ifval($1,$1,FLAGS) for maximum warnings],
VAR,[VAR="no, unknown"
 AC_LANG_SAVE
 AC_LANG_C
 ac_save_[]FLAGS="$[]FLAGS"
for ac_arg dnl
in "-pedantic  % -Wall"       dnl   GCC
   "-xstrconst % -v"          dnl Solaris C
   "-std1      % -verbose -w0 -warnprotos" dnl Digital Unix
   "-qlanglvl=ansi % -qsrcmsg -qinfo=all:noppt:noppc:noobs:nocnd" dnl AIX
   "-ansi -ansiE % -fullwarn" dnl IRIX
   "+ESlit     % +w1"         dnl HP-UX C
   "-Xc        % -pvctl[,]fullmsg" dnl NEC SX-5 (Super-UX 10)
   "-h conform % -h msglevel 2" dnl Cray C (Unicos)
   #
do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
   AC_TRY_COMPILE([],[return 0;],
   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
done
 FLAGS="$ac_save_[]FLAGS"
 AC_LANG_RESTORE
])
case ".$VAR" in
     .ok|.ok,*) m4_ifvaln($3,$3) ;;
   .|.no|.no,*) m4_ifvaln($4,$4,[m4_ifval($2,[
        AC_RUN_LOG([: m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $2"])
                      m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $2"])]) ;;
   *) m4_ifvaln($3,$3,[
   if echo " $[]m4_ifval($1,$1,FLAGS) " | grep " $VAR " 2>&1 >/dev/null
   then AC_RUN_LOG([: m4_ifval($1,$1,FLAGS) does contain $VAR])
   else AC_RUN_LOG([: m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $VAR"])
                      m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $VAR"
   fi ]) ;;
esac
AS_VAR_POPDEF([VAR])dnl
AS_VAR_POPDEF([FLAGS])dnl
])

dnl the only difference - the LANG selection... and the default FLAGS

AC_DEFUN([AX_CXXFLAGS_WARN_ALL],[dnl
AS_VAR_PUSHDEF([FLAGS],[CXXFLAGS])dnl
AS_VAR_PUSHDEF([VAR],[ac_cv_cxxflags_warn_all])dnl
AC_CACHE_CHECK([m4_ifval($1,$1,FLAGS) for maximum warnings],
VAR,[VAR="no, unknown"
 AC_LANG_SAVE
 AC_LANG_CPLUSPLUS
 ac_save_[]FLAGS="$[]FLAGS"
for ac_arg dnl
in "-pedantic  % -Wall"       dnl   GCC
   "-xstrconst % -v"          dnl Solaris C
   "-std1      % -verbose -w0 -warnprotos" dnl Digital Unix
   "-qlanglvl=ansi % -qsrcmsg -qinfo=all:noppt:noppc:noobs:nocnd" dnl AIX
   "-ansi -ansiE % -fullwarn" dnl IRIX
   "+ESlit     % +w1"         dnl HP-UX C
   "-Xc        % -pvctl[,]fullmsg" dnl NEC SX-5 (Super-UX 10)
   "-h conform % -h msglevel 2" dnl Cray C (Unicos)
   #
do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
   AC_TRY_COMPILE([],[return 0;],
   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
done
 FLAGS="$ac_save_[]FLAGS"
 AC_LANG_RESTORE
])
case ".$VAR" in
     .ok|.ok,*) m4_ifvaln($3,$3) ;;
   .|.no|.no,*) m4_ifvaln($4,$4,[m4_ifval($2,[
        AC_RUN_LOG([: m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $2"])
                      m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $2"])]) ;;
   *) m4_ifvaln($3,$3,[
   if echo " $[]m4_ifval($1,$1,FLAGS) " | grep " $VAR " 2>&1 >/dev/null
   then AC_RUN_LOG([: m4_ifval($1,$1,FLAGS) does contain $VAR])
   else AC_RUN_LOG([: m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $VAR"])
                      m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $VAR"
   fi ]) ;;
esac
AS_VAR_POPDEF([VAR])dnl
AS_VAR_POPDEF([FLAGS])dnl
])

dnl  implementation tactics:
dnl   the for-argument contains a list of options. The first part of
dnl   these does only exist to detect the compiler - usually it is
dnl   a global option to enable -ansi or -extrawarnings. All other
dnl   compilers will fail about it. That was needed since a lot of
dnl   compilers will give false positives for some option-syntax
dnl   like -Woption or -Xoption as they think of it is a pass-through
dnl   to later compile stages or something. The "%" is used as a
dnl   delimimiter. A non-option comment can be given after "%%" marks
dnl   which will be shown but not added to the respective C/CXXFLAGS.