--- /dev/null
+# ===========================================================================
+# http://www.gnu.org/software/autoconf-archive/ax_cflags_warn_all.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+# AX_CFLAGS_WARN_ALL [(shellvar [,default, [A/NA]])]
+# AX_CXXFLAGS_WARN_ALL [(shellvar [,default, [A/NA]])]
+# AX_FCFLAGS_WARN_ALL [(shellvar [,default, [A/NA]])]
+#
+# DESCRIPTION
+#
+# Try to find a compiler option that enables most reasonable warnings.
+#
+# For the GNU compiler it will be -Wall (and -ansi -pedantic) The result
+# is added to the shellvar being CFLAGS, CXXFLAGS, or FCFLAGS by default.
+#
+# Currently this macro knows about the GCC, Solaris, Digital Unix, AIX,
+# HP-UX, IRIX, NEC SX-5 (Super-UX 10), Cray J90 (Unicos 10.0.0.8), and
+# Intel compilers. For a given compiler, the Fortran flags are much more
+# experimental than their C equivalents.
+#
+# - $1 shell-variable-to-add-to : CFLAGS, CXXFLAGS, or FCFLAGS
+# - $2 add-value-if-not-found : nothing
+# - $3 action-if-found : add value to shellvariable
+# - $4 action-if-not-found : nothing
+#
+# NOTE: These macros depend on AX_APPEND_FLAG.
+#
+# LICENSE
+#
+# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+# Copyright (c) 2010 Rhys Ulerich <rhys.ulerich@gmail.com>
+#
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+#
+# 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 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.
+
+#serial 15
+
+AC_DEFUN([AX_FLAGS_WARN_ALL],[dnl
+AS_VAR_PUSHDEF([FLAGS],[_AC_LANG_PREFIX[]FLAGS])dnl
+AS_VAR_PUSHDEF([VAR],[ac_cv_[]_AC_LANG_ABBREV[]flags_warn_all])dnl
+AC_CACHE_CHECK([m4_ifval($1,$1,FLAGS) for maximum warnings],
+VAR,[VAR="no, unknown"
+ac_save_[]FLAGS="$[]FLAGS"
+for ac_arg dnl
+in "-warn all % -warn all" dnl Intel
+ "-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_COMPILE_IFELSE([AC_LANG_PROGRAM],
+ [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
+done
+FLAGS="$ac_save_[]FLAGS"
+])
+AS_VAR_POPDEF([FLAGS])dnl
+AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
+case ".$VAR" in
+ .ok|.ok,*) m4_ifvaln($3,$3) ;;
+ .|.no|.no,*) m4_default($4,[m4_ifval($2,[AX_APPEND_FLAG([$2], [$1])])]) ;;
+ *) m4_default($3,[AX_APPEND_FLAG([$VAR], [$1])]) ;;
+esac
+AS_VAR_POPDEF([VAR])dnl
+])dnl AX_FLAGS_WARN_ALL
+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 delimiter. A non-option comment can be given after "%%" marks
+dnl which will be shown but not added to the respective C/CXXFLAGS.
+
+AC_DEFUN([AX_CFLAGS_WARN_ALL],[dnl
+AC_LANG_PUSH([C])
+AX_FLAGS_WARN_ALL([$1], [$2], [$3], [$4])
+AC_LANG_POP([C])
+])
+
+AC_DEFUN([AX_CXXFLAGS_WARN_ALL],[dnl
+AC_LANG_PUSH([C++])
+AX_FLAGS_WARN_ALL([$1], [$2], [$3], [$4])
+AC_LANG_POP([C++])
+])
+
+AC_DEFUN([AX_FCFLAGS_WARN_ALL],[dnl
+AC_LANG_PUSH([Fortran])
+AX_FLAGS_WARN_ALL([$1], [$2], [$3], [$4])
+AC_LANG_POP([Fortran])
+])