# =========================================================================== # http://www.gnu.org/software/autoconf-archive/ax_check_gnu_make.html # =========================================================================== # # SYNOPSIS # # AX_CHECK_GNU_MAKE() # # DESCRIPTION # # This macro searches for a GNU version of make. If a match is found: # # * The makefile variable `ifGNUmake' is set to the empty string, otherwise # it is set to "#". This is useful for including a special features in a # Makefile, which cannot be handled by other versions of make. # * The variable `_cv_gnu_make_command` is set to the command to invoke # GNU make if it exists, the empty string otherwise. # * The variable `ax_cv_gnu_make_command` is set to the command to invoke # GNU make by copying `_cv_gnu_make_command`, otherwise it is unset. # * If GNU Make is found, its version is extracted from the output of # `make --version` as the last field of a record of space-separated # columns and saved into the variable `ax_check_gnu_make_version`. # # Here is an example of its use: # # Makefile.in might contain: # # # A failsafe way of putting a dependency rule into a makefile # $(DEPEND): # $(CC) -MM $(srcdir)/*.c > $(DEPEND) # # @ifGNUmake@ ifeq ($(DEPEND),$(wildcard $(DEPEND))) # @ifGNUmake@ include $(DEPEND) # @ifGNUmake@ endif # # Then configure.in would normally contain: # # AX_CHECK_GNU_MAKE() # AC_OUTPUT(Makefile) # # Then perhaps to cause gnu make to override any other make, we could do # something like this (note that GNU make always looks for GNUmakefile # first): # # if ! test x$_cv_gnu_make_command = x ; then # mv Makefile GNUmakefile # echo .DEFAULT: > Makefile ; # echo \ $_cv_gnu_make_command \$@ >> Makefile; # fi # # Then, if any (well almost any) other make is called, and GNU make also # exists, then the other make wraps the GNU make. # # LICENSE # # Copyright (c) 2008 John Darrington <j.darrington@elvis.murdoch.edu.au> # Copyright (c) 2015 Enrico M. Crisostomo <enrico.m.crisostomo@gmail.com> # # Copying and distribution of this file, with or without modification, are # permitted in any medium without royalty provided the copyright notice # and this notice are preserved. This file is offered as-is, without any # warranty. #serial 8 AC_DEFUN([AX_CHECK_GNU_MAKE],dnl [AC_PROG_AWK AC_CACHE_CHECK([for GNU make],[_cv_gnu_make_command],[dnl _cv_gnu_make_command="" ; dnl Search all the common names for GNU make for a in "$MAKE" make gmake gnumake ; do if test -z "$a" ; then continue ; fi ; if "$a" --version 2> /dev/null | grep GNU 2>&1 > /dev/null ; then _cv_gnu_make_command=$a ; AX_CHECK_GNU_MAKE_HEADLINE=$("$a" --version 2> /dev/null | grep "GNU Make") ax_check_gnu_make_version=$(echo ${AX_CHECK_GNU_MAKE_HEADLINE} | ${AWK} -F " " '{ print $(NF); }') break ; fi done ;]) dnl If there was a GNU version, then set @ifGNUmake@ to the empty string, '#' otherwise AS_VAR_IF([_cv_gnu_make_command], [""], [AS_VAR_SET([ifGNUmake], ["#"])], [AS_VAR_SET([ifGNUmake], [""])]) AS_VAR_IF([_cv_gnu_make_command], [""], [AS_UNSET(ax_cv_gnu_make_command)], [AS_VAR_SET([ax_cv_gnu_make_command], [${_cv_gnu_make_command}])]) AC_SUBST([ifGNUmake]) ])