config: Sync with GCC

[thirdparty/binutils-gdb.git] / config / acx.m4

# Autoconf M4 include file defining utility macros for complex Canadian
# cross builds.

dnl ####
dnl # _GCC_TOPLEV_NONCANONICAL_BUILD
dnl # $build_alias or canonical $build if blank.
dnl # Used when we would use $build_alias, but empty is not OK.
AC_DEFUN([_GCC_TOPLEV_NONCANONICAL_BUILD],
[AC_REQUIRE([AC_CANONICAL_BUILD]) []dnl
case ${build_alias} in
  "") build_noncanonical=${build} ;;
  *) build_noncanonical=${build_alias} ;;
esac
]) []dnl # _GCC_TOPLEV_NONCANONICAL_BUILD

dnl ####
dnl # _GCC_TOPLEV_NONCANONICAL_HOST
dnl # $host_alias, or $build_noncanonical if blank.
dnl # Used when we would use $host_alias, but empty is not OK.
AC_DEFUN([_GCC_TOPLEV_NONCANONICAL_HOST],
[AC_REQUIRE([_GCC_TOPLEV_NONCANONICAL_BUILD]) []dnl
case ${host_alias} in
  "") host_noncanonical=${build_noncanonical} ;;
  *) host_noncanonical=${host_alias} ;;
esac
]) []dnl # _GCC_TOPLEV_NONCANONICAL_HOST

dnl ####
dnl # _GCC_TOPLEV_NONCANONICAL_TARGET
dnl # $target_alias or $host_noncanonical if blank.
dnl # Used when we would use $target_alias, but empty is not OK.
AC_DEFUN([_GCC_TOPLEV_NONCANONICAL_TARGET],
[AC_REQUIRE([_GCC_TOPLEV_NONCANONICAL_HOST]) []dnl
case ${target_alias} in
  "") target_noncanonical=${host_noncanonical} ;;
  *) target_noncanonical=${target_alias} ;;
esac
]) []dnl # _GCC_TOPLEV_NONCANONICAL_TARGET

dnl ####
dnl # ACX_NONCANONICAL_BUILD
dnl # Like underscored version, but AC_SUBST's.
AC_DEFUN([ACX_NONCANONICAL_BUILD],
[AC_REQUIRE([_GCC_TOPLEV_NONCANONICAL_BUILD]) []dnl
AC_SUBST(build_noncanonical)
]) []dnl # ACX_NONCANONICAL_BUILD

dnl ####
dnl # ACX_NONCANONICAL_HOST
dnl # Like underscored version, but AC_SUBST's.
AC_DEFUN([ACX_NONCANONICAL_HOST],
[AC_REQUIRE([_GCC_TOPLEV_NONCANONICAL_HOST]) []dnl
AC_SUBST(host_noncanonical)
]) []dnl # ACX_NONCANONICAL_HOST

dnl ####
dnl # ACX_NONCANONICAL_TARGET
dnl # Like underscored version, but AC_SUBST's.
AC_DEFUN([ACX_NONCANONICAL_TARGET],
[AC_REQUIRE([_GCC_TOPLEV_NONCANONICAL_TARGET]) []dnl
AC_SUBST(target_noncanonical)
]) []dnl # ACX_NONCANONICAL_TARGET

dnl ####
dnl # GCC_TOPLEV_SUBDIRS
dnl # GCC & friends build 'build', 'host', and 'target' tools.  These must
dnl # be separated into three well-known subdirectories of the build directory:
dnl # build_subdir, host_subdir, and target_subdir.  The values are determined
dnl # here so that they can (theoretically) be changed in the future.  They
dnl # were previously reproduced across many different files.
dnl #
dnl # This logic really amounts to very little with autoconf 2.13; it will
dnl # amount to a lot more with autoconf 2.5x.
AC_DEFUN([GCC_TOPLEV_SUBDIRS],
[AC_REQUIRE([_GCC_TOPLEV_NONCANONICAL_TARGET]) []dnl
AC_REQUIRE([_GCC_TOPLEV_NONCANONICAL_BUILD]) []dnl

# post-stage1 host modules use a different CC_FOR_BUILD so, in order to
# have matching libraries, they should use host libraries: Makefile.tpl
# arranges to pass --with-build-libsubdir=$(HOST_SUBDIR).
# However, they still use the build modules, because the corresponding
# host modules (e.g. bison) are only built for the host when bootstrap
# finishes. So:
# - build_subdir is where we find build modules, and never changes.
# - build_libsubdir is where we find build libraries, and can be overridden.

# Prefix 'build-' so this never conflicts with target_subdir.
build_subdir="build-${build_noncanonical}"
AC_ARG_WITH(build-libsubdir,
[  --with-build-libsubdir=[DIR]  Directory where to find libraries for build system],
build_libsubdir="$withval",
build_libsubdir="$build_subdir")
# --srcdir=. covers the toplevel, while "test -d" covers the subdirectories
if ( test $srcdir = . && test -d gcc ) \
   || test -d $srcdir/../host-${host_noncanonical}; then
  host_subdir="host-${host_noncanonical}"
else
  host_subdir=.
fi
# No prefix.
target_subdir=${target_noncanonical}
AC_SUBST([build_libsubdir]) []dnl
AC_SUBST([build_subdir]) []dnl
AC_SUBST([host_subdir]) []dnl
AC_SUBST([target_subdir]) []dnl
]) []dnl # GCC_TOPLEV_SUBDIRS


####
# _NCN_TOOL_PREFIXES:  Some stuff that oughtta be done in AC_CANONICAL_SYSTEM 
# or AC_INIT.
# These demand that AC_CANONICAL_SYSTEM be called beforehand.
AC_DEFUN([_NCN_TOOL_PREFIXES],
[ncn_tool_prefix=
test -n "$host_alias" && ncn_tool_prefix=$host_alias-
ncn_target_tool_prefix=
test -n "$target_alias" && ncn_target_tool_prefix=$target_alias-
]) []dnl # _NCN_TOOL_PREFIXES

####
# NCN_STRICT_CHECK_TOOLS(variable, progs-to-check-for,[value-if-not-found],[path])
# Like plain AC_CHECK_TOOLS, but require prefix if build!=host.

AC_DEFUN([NCN_STRICT_CHECK_TOOLS],
[AC_REQUIRE([_NCN_TOOL_PREFIXES]) []dnl
AC_ARG_VAR([$1], [$1 for the host])

if test -n "[$]$1"; then
  ac_cv_prog_$1=[$]$1
elif test -n "$ac_cv_prog_$1"; then
  $1=$ac_cv_prog_$1
fi

if test -n "$ac_cv_prog_$1"; then
  for ncn_progname in $2; do
    AC_CHECK_PROG([$1], [${ncn_progname}], [${ncn_progname}], , [$4])
  done
fi

for ncn_progname in $2; do
  if test -n "$ncn_tool_prefix"; then
    AC_CHECK_PROG([$1], [${ncn_tool_prefix}${ncn_progname}], 
                  [${ncn_tool_prefix}${ncn_progname}], , [$4])
  fi
  if test -z "$ac_cv_prog_$1" && test $build = $host ; then
    AC_CHECK_PROG([$1], [${ncn_progname}], [${ncn_progname}], , [$4]) 
  fi
  test -n "$ac_cv_prog_$1" && break
done

if test -z "$ac_cv_prog_$1" ; then
  ifelse([$3],[], [set dummy $2
  if test $build = $host ; then
    $1="[$]2"
  else
    $1="${ncn_tool_prefix}[$]2"
  fi], [$1="$3"])
fi
]) []dnl # NCN_STRICT_CHECK_TOOLS

####
# NCN_STRICT_CHECK_TARGET_TOOLS(variable, progs-to-check-for,[value-if-not-found],[path])
# Like CVS Autoconf AC_CHECK_TARGET_TOOLS, but require prefix if build!=target.

AC_DEFUN([NCN_STRICT_CHECK_TARGET_TOOLS],
[AC_REQUIRE([_NCN_TOOL_PREFIXES]) []dnl
AC_ARG_VAR([$1], patsubst([$1], [_FOR_TARGET$], [])[ for the target])

if test -n "[$]$1"; then
  ac_cv_prog_$1=[$]$1
elif test -n "$ac_cv_prog_$1"; then
  $1=$ac_cv_prog_$1
fi

if test -n "$ac_cv_prog_$1"; then
  for ncn_progname in $2; do
    AC_CHECK_PROG([$1], [${ncn_progname}], [${ncn_progname}], , [$4])
  done
fi

if test -z "$ac_cv_prog_$1" && test -n "$with_build_time_tools"; then
  for ncn_progname in $2; do
    AC_MSG_CHECKING([for ${ncn_progname} in $with_build_time_tools])
    if test -x $with_build_time_tools/${ncn_progname}; then
      ac_cv_prog_$1=$with_build_time_tools/${ncn_progname}
      AC_MSG_RESULT(yes)
      break
    else
      AC_MSG_RESULT(no)
    fi
  done
fi

if test -z "$ac_cv_prog_$1"; then
  for ncn_progname in $2; do
    if test -n "$ncn_target_tool_prefix"; then
      AC_CHECK_PROG([$1], [${ncn_target_tool_prefix}${ncn_progname}], 
                    [${ncn_target_tool_prefix}${ncn_progname}], , [$4])
    fi
    if test -z "$ac_cv_prog_$1" && test $build = $target ; then
      AC_CHECK_PROG([$1], [${ncn_progname}], [${ncn_progname}], , [$4]) 
    fi
    test -n "$ac_cv_prog_$1" && break
  done
fi
  
if test -z "$ac_cv_prog_$1" ; then
  ifelse([$3],[], [set dummy $2
  if test $build = $target ; then
    $1="[$]2"
  else
    $1="${ncn_target_tool_prefix}[$]2"
  fi], [$1="$3"])
else
  $1="$ac_cv_prog_$1"
fi
]) []dnl # NCN_STRICT_CHECK_TARGET_TOOLS
  

# Backported from Autoconf 2.5x; can go away when and if
# we switch.  Put the OS path separator in $PATH_SEPARATOR.
AC_DEFUN([ACX_PATH_SEP], [
# The user is always right.
if test "${PATH_SEPARATOR+set}" != set; then
  echo "#! /bin/sh" >conf$$.sh
  echo  "exit 0"   >>conf$$.sh
  chmod +x conf$$.sh
  if (PATH="/nonexistent;."; conf$$.sh) >/dev/null 2>&1; then
    PATH_SEPARATOR=';'
  else
    PATH_SEPARATOR=: 
  fi
  rm -f conf$$.sh
fi
])


dnl ####
dnl # GCC_BASE_VER
dnl # Determine GCC version number to use in compiler directories.

AC_DEFUN([GCC_BASE_VER],
[
  get_gcc_base_ver="cat"
  AC_ARG_WITH(gcc-major-version-only,
  [AS_HELP_STRING([--with-gcc-major-version-only], [use only GCC major number in filesystem paths])],
  [if test x$with_gcc_major_version_only = xyes ; then
    changequote(,)dnl
    get_gcc_base_ver="sed -e 's/^\([0-9]*\).*/\1/'"
    changequote([,])dnl
  fi
  ])
  AC_SUBST(get_gcc_base_ver)
])


AC_DEFUN([ACX_TOOL_DIRS], [
AC_REQUIRE([ACX_PATH_SEP])
AC_REQUIRE([GCC_BASE_VER])
if test "x$exec_prefix" = xNONE; then
        if test "x$prefix" = xNONE; then
                gcc_cv_tool_prefix=$ac_default_prefix
        else
                gcc_cv_tool_prefix=$prefix
        fi
else
        gcc_cv_tool_prefix=$exec_prefix
fi

# If there is no compiler in the tree, use the PATH only.  In any
# case, if there is no compiler in the tree nobody should use
# AS_FOR_TARGET and LD_FOR_TARGET.
if test x$host = x$build && test -f $srcdir/gcc/BASE-VER; then
    if test x$with_gcc_major_version_only = xyes ; then
        changequote(,)dnl
        gcc_version=`sed -e 's/^\([0-9]*\).*$/\1/' $srcdir/gcc/BASE-VER`
        changequote([,])dnl
    else
        gcc_version=`cat $srcdir/gcc/BASE-VER`
    fi
    gcc_cv_tool_dirs="$gcc_cv_tool_prefix/libexec/gcc/$target_noncanonical/$gcc_version$PATH_SEPARATOR"
    gcc_cv_tool_dirs="$gcc_cv_tool_dirs$gcc_cv_tool_prefix/libexec/gcc/$target_noncanonical$PATH_SEPARATOR"
    gcc_cv_tool_dirs="$gcc_cv_tool_dirs/usr/lib/gcc/$target_noncanonical/$gcc_version$PATH_SEPARATOR"
    gcc_cv_tool_dirs="$gcc_cv_tool_dirs/usr/lib/gcc/$target_noncanonical$PATH_SEPARATOR"
    gcc_cv_tool_dirs="$gcc_cv_tool_dirs$gcc_cv_tool_prefix/$target_noncanonical/bin/$target_noncanonical/$gcc_version$PATH_SEPARATOR"
    gcc_cv_tool_dirs="$gcc_cv_tool_dirs$gcc_cv_tool_prefix/$target_noncanonical/bin$PATH_SEPARATOR"
else
    gcc_cv_tool_dirs=
fi

if test x$build = x$target && test -n "$md_exec_prefix"; then
        gcc_cv_tool_dirs="$gcc_cv_tool_dirs$md_exec_prefix$PATH_SEPARATOR"
fi

]) []dnl # ACX_TOOL_DIRS

# ACX_HAVE_GCC_FOR_TARGET
# Check if the variable GCC_FOR_TARGET really points to a GCC binary.
AC_DEFUN([ACX_HAVE_GCC_FOR_TARGET], [
cat > conftest.c << \EOF
#ifdef __GNUC__
  gcc_yay;
#endif
EOF
if ($GCC_FOR_TARGET -E conftest.c | grep gcc_yay) > /dev/null 2>&1; then
  have_gcc_for_target=yes
else
  GCC_FOR_TARGET=${ncn_target_tool_prefix}gcc
  have_gcc_for_target=no
fi
rm conftest.c
])

# ACX_CHECK_INSTALLED_TARGET_TOOL(VAR, PROG)
# Searching for installed target binutils.  We need to take extra care,
# else we may find the wrong assembler, linker, etc., and lose.
#
# First try --with-build-time-tools, if specified.
#
# For build != host, we ask the installed GCC for the name of the tool it
# uses, and accept it if it is an absolute path.  This is because the
# only good choice for a compiler is the same GCC version that is being
# installed (or we couldn't make target libraries), and we assume that
# on the host system we'll have not only the same GCC version, but also
# the same binutils version.
#
# For build == host, search the same directories that the installed
# compiler will search.  We used to do this for the assembler, linker,
# and nm only; for simplicity of configuration, however, we extend this
# criterion to tools (such as ar and ranlib) that are never invoked by
# the compiler, to avoid mismatches.
#
# Also note we have to check MD_EXEC_PREFIX before checking the user's path
# if build == target.  This makes the most sense only when bootstrapping,
# but we also do so when build != host.  In this case, we hope that the
# build and host systems will have similar contents of MD_EXEC_PREFIX.
#
# If we do not find a suitable binary, then try the user's path.

AC_DEFUN([ACX_CHECK_INSTALLED_TARGET_TOOL], [
AC_REQUIRE([ACX_TOOL_DIRS])
AC_REQUIRE([ACX_HAVE_GCC_FOR_TARGET])
if test -z "$ac_cv_path_$1" ; then
  if test -n "$with_build_time_tools"; then
    AC_MSG_CHECKING([for $2 in $with_build_time_tools])
    if test -x $with_build_time_tools/$2; then
      $1=`cd $with_build_time_tools && pwd`/$2
      ac_cv_path_$1=[$]$1
      AC_MSG_RESULT([$ac_cv_path_$1])
    else
      AC_MSG_RESULT(no)
    fi
  elif test $build != $host && test $have_gcc_for_target = yes; then
    $1=`$GCC_FOR_TARGET --print-prog-name=$2`
    test [$]$1 = $2 && $1=
    test -n "[$]$1" && ac_cv_path_$1=[$]$1
  fi
fi
if test -z "$ac_cv_path_$1" && test -n "$gcc_cv_tool_dirs"; then
  AC_PATH_PROG([$1], [$2], [], [$gcc_cv_tool_dirs])
fi
if test -z "$ac_cv_path_$1" ; then
  NCN_STRICT_CHECK_TARGET_TOOLS([$1], [$2])
else
  $1=$ac_cv_path_$1
fi
]) []dnl # ACX_CHECK_INSTALLED_TARGET_TOOL

###
# AC_PROG_CPP_WERROR
# Used for autoconf 2.5x to force AC_PREPROC_IFELSE to reject code which
# triggers warnings from the preprocessor.  Will be in autoconf 2.58.
# For now, using this also overrides header checks to use only the
# preprocessor (matches 2.13 behavior; matching 2.58's behavior is a
# bit harder from here).
# Eventually autoconf will default to checking headers with the compiler
# instead, and we'll have to do this differently.

AC_DEFUN([AC_PROG_CPP_WERROR],
[AC_REQUIRE([AC_PROG_CPP])dnl
m4_define([AC_CHECK_HEADER],m4_defn([_AC_CHECK_HEADER_OLD]))
ac_c_preproc_warn_flag=yes])# AC_PROG_CPP_WERROR

# Test for GNAT.
# We require the gnatbind & gnatmake programs, as well as a compiler driver
# that understands Ada.  We use the user's CC setting, already found, and
# possibly add $1 to the command-line parameters.
#
# Sets the shell variable have_gnat to yes or no as appropriate, and
# substitutes GNATBIND and GNATMAKE.
AC_DEFUN([ACX_PROG_GNAT],
[AC_REQUIRE([AC_CHECK_TOOL_PREFIX])
AC_REQUIRE([AC_PROG_CC])
AC_CHECK_TOOL(GNATBIND, gnatbind, no)
AC_CHECK_TOOL(GNATMAKE, gnatmake, no)
AC_CACHE_CHECK([whether compiler driver understands Ada],
		 acx_cv_cc_gcc_supports_ada,
[cat >conftest.adb <<EOF
procedure conftest is begin null; end conftest;
EOF
acx_cv_cc_gcc_supports_ada=no
# There is a bug in old released versions of GCC which causes the
# driver to exit successfully when the appropriate language module
# has not been installed.  This is fixed in 2.95.4, 3.0.2, and 3.1.
# Therefore we must check for the error message as well as an
# unsuccessful exit.
# Other compilers, like HP Tru64 UNIX cc, exit successfully when
# given a .adb file, but produce no object file.  So we must check
# if an object file was really produced to guard against this.
errors=`(${CC} $1[]m4_ifval([$1], [ ])-c conftest.adb) 2>&1 || echo failure`
if test x"$errors" = x && test -f conftest.$ac_objext; then
  acx_cv_cc_gcc_supports_ada=yes
fi
rm -f conftest.*])

if test "x$GNATBIND" != xno && test "x$GNATMAKE" != xno && test x$acx_cv_cc_gcc_supports_ada != xno; then
  have_gnat=yes
else
  have_gnat=no
fi
])

dnl 'make compare' can be significantly faster, if cmp itself can
dnl skip bytes instead of using tail.  The test being performed is
dnl "if cmp --ignore-initial=2 t1 t2 && ! cmp --ignore-initial=1 t1 t2"
dnl but we need to sink errors and handle broken shells.  We also test
dnl for the parameter format "cmp file1 file2 skip1 skip2" which is
dnl accepted by cmp on some systems.
AC_DEFUN([ACX_PROG_CMP_IGNORE_INITIAL],
[AC_CACHE_CHECK([how to compare bootstrapped objects], gcc_cv_prog_cmp_skip,
[ echo abfoo >t1
  echo cdfoo >t2
  gcc_cv_prog_cmp_skip='tail -c +17 $$f1 > tmp-foo1; tail -c +17 $$f2 > tmp-foo2; cmp tmp-foo1 tmp-foo2'
  if cmp t1 t2 2 2 > /dev/null 2>&1; then
    if cmp t1 t2 1 1 > /dev/null 2>&1; then
      :
    else
      gcc_cv_prog_cmp_skip='cmp $$f1 $$f2 16 16'
    fi
  fi
  if cmp --ignore-initial=2 t1 t2 > /dev/null 2>&1; then
    if cmp --ignore-initial=1 t1 t2 > /dev/null 2>&1; then
      :
    else
      gcc_cv_prog_cmp_skip='cmp --ignore-initial=16 $$f1 $$f2'
    fi
  fi
  rm t1 t2
])
do_compare="$gcc_cv_prog_cmp_skip"
AC_SUBST(do_compare)
])

dnl See whether we can include both string.h and strings.h.
AC_DEFUN([ACX_HEADER_STRING],
[AC_CACHE_CHECK([whether string.h and strings.h may both be included],
  gcc_cv_header_string,
[AC_TRY_COMPILE([#include <string.h>
#include <strings.h>], , gcc_cv_header_string=yes, gcc_cv_header_string=no)])
if test $gcc_cv_header_string = yes; then
  AC_DEFINE(STRING_WITH_STRINGS, 1, [Define if you can safely include both <string.h> and <strings.h>.])
fi
])

dnl See if stdbool.h properly defines bool and true/false.
dnl Check whether _Bool is built-in.
AC_DEFUN([ACX_HEADER_STDBOOL],
[AC_CACHE_CHECK([for working stdbool.h],
  ac_cv_header_stdbool_h,
[AC_TRY_COMPILE([#include <stdbool.h>],
[bool foo = false;],
ac_cv_header_stdbool_h=yes, ac_cv_header_stdbool_h=no)])
if test $ac_cv_header_stdbool_h = yes; then
  AC_DEFINE(HAVE_STDBOOL_H, 1,
  [Define if you have a working <stdbool.h> header file.])
fi
AC_CACHE_CHECK(for built-in _Bool, gcc_cv_c__bool,
[AC_TRY_COMPILE(,
[_Bool foo;],
gcc_cv_c__bool=yes, gcc_cv_c__bool=no)
])
if test $gcc_cv_c__bool = yes; then
  AC_DEFINE(HAVE__BOOL, 1, [Define if the \`_Bool' type is built-in.])
fi
])

dnl See if hard links work and if not, try to substitute $1 or simple copy.
AC_DEFUN([ACX_PROG_LN],
[AC_MSG_CHECKING(whether ln works)
AC_CACHE_VAL(acx_cv_prog_LN,
[rm -f conftestdata_t
echo >conftestdata_f
if ln conftestdata_f conftestdata_t 2>/dev/null
then
  acx_cv_prog_LN=ln
else
  acx_cv_prog_LN=no
fi
rm -f conftestdata_f conftestdata_t
])dnl
if test $acx_cv_prog_LN = no; then
  LN="ifelse([$1],,cp,[$1])"
  AC_MSG_RESULT([no, using $LN])
else
  LN="$acx_cv_prog_LN"
  AC_MSG_RESULT(yes)
fi
AC_SUBST(LN)dnl
])

dnl GCC_TARGET_TOOL(PROGRAM, TARGET-VAR, HOST-VAR, IN-TREE-TOOL, LANGUAGE)
AC_DEFUN([GCC_TARGET_TOOL],
[AC_MSG_CHECKING(where to find the target $1)
if test "x${build}" != "x${host}" ; then
  if expr "x[$]$2" : "x/" > /dev/null; then
    # We already found the complete path
    ac_dir=`dirname [$]$2`
    AC_MSG_RESULT(pre-installed in $ac_dir)
  else
    # Canadian cross, just use what we found
    AC_MSG_RESULT(pre-installed)
  fi
else
  ifelse([$4],,,
  [ok=yes
  case " ${configdirs} " in
    *" patsubst([$4], [/.*], []) "*) ;;
    *) ok=no ;;
  esac
  ifelse([$5],,, 
  [case ,${enable_languages}, in
    *,$5,*) ;;
    *) ok=no ;;
  esac])
  if test $ok = yes; then
    # An in-tree tool is available and we can use it
    $2='$$r/$(HOST_SUBDIR)/$4'
    AC_MSG_RESULT(just compiled)
  el])if expr "x[$]$2" : "x/" > /dev/null; then
    # We already found the complete path
    ac_dir=`dirname [$]$2`
    AC_MSG_RESULT(pre-installed in $ac_dir)
  elif test "x$target" = "x$host"; then
    # We can use an host tool
    $2='$($3)'
    AC_MSG_RESULT(host tool)
  else
    # We need a cross tool
    AC_MSG_RESULT(pre-installed)
  fi
fi
AC_SUBST($2)])


dnl Locate a program and check that its version is acceptable.
dnl ACX_PROG_CHECK_VER(var, name, version-switch,
dnl                    version-extract-regexp, version-glob)
AC_DEFUN([ACX_CHECK_PROG_VER],[
  AC_CHECK_PROG([$1], [$2], [$2])
  if test -n "[$]$1"; then
    # Found it, now check the version.
    AC_CACHE_CHECK([for modern $2],
                   [gcc_cv_prog_$2_modern],
                   [ac_prog_version=`eval [$]$1 $3 2>&1 |
                                     sed -n 's/^.*patsubst([[$4]],/,\/).*$/\1/p'`

                    [case $ac_prog_version in
                      '')  gcc_cv_prog_$2_modern=no;;
                      $5)  gcc_cv_prog_$2_modern=yes;;
                      *)   gcc_cv_prog_$2_modern=no;;
                    esac]
                   ])
  else
    gcc_cv_prog_$2_modern=no
  fi
  if test $gcc_cv_prog_$2_modern = no; then
    $1="${CONFIG_SHELL-/bin/sh} $ac_aux_dir/missing $2"
  fi
])

dnl Support the --with-pkgversion configure option.
dnl ACX_PKGVERSION(default-pkgversion)
AC_DEFUN([ACX_PKGVERSION],[
  AC_ARG_WITH(pkgversion,
    AS_HELP_STRING([--with-pkgversion=PKG],
                   [Use PKG in the version string in place of "$1"]),
    [case "$withval" in
      yes) AC_MSG_ERROR([package version not specified]) ;;
      no)  PKGVERSION= ;;
      *)   PKGVERSION="($withval) " ;;
     esac],
    PKGVERSION="($1) "
  )
  AC_SUBST(PKGVERSION)
])

dnl Support the --with-bugurl configure option.
dnl ACX_BUGURL(default-bugurl)
AC_DEFUN([ACX_BUGURL],[
  AC_ARG_WITH(bugurl,
    AS_HELP_STRING([--with-bugurl=URL],
                   [Direct users to URL to report a bug]),
    [case "$withval" in
      yes) AC_MSG_ERROR([bug URL not specified]) ;;
      no)  BUGURL=
	   ;;
      *)   BUGURL="$withval"
	   ;;
     esac],
     BUGURL="$1"
  )
  case ${BUGURL} in
  "")
    REPORT_BUGS_TO=
    REPORT_BUGS_TEXI=
    ;;
  *)
    REPORT_BUGS_TO="<$BUGURL>"
    REPORT_BUGS_TEXI=@uref{`echo "$BUGURL" | sed 's/@/@@/g'`}
    ;;
  esac;
  AC_SUBST(REPORT_BUGS_TO)
  AC_SUBST(REPORT_BUGS_TEXI)
])

dnl ####
dnl # ACX_CHECK_CYGWIN_CAT_WORKS
dnl # On Cygwin hosts, check that the cat command ignores 
dnl # carriage returns as otherwise builds will not work.
dnl # See binutils PR 4334 for more details.
AC_DEFUN([ACX_CHECK_CYGWIN_CAT_WORKS],[
AC_MSG_CHECKING([to see if cat works as expected])
echo a >cygwin-cat-check
if test `cat cygwin-cat-check` = a ; then
  rm cygwin-cat-check
  AC_MSG_RESULT(yes)
else
  rm cygwin-cat-check
  AC_MSG_RESULT(no)
  AC_MSG_ERROR([The cat command does not ignore carriage return characters.
  Please either mount the build directory in binary mode or run the following
  commands before running any configure script:
set -o igncr
export SHELLOPTS 
  ])
fi
])