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3rdparty/c-ares-1.18.1/m4/ax_check_gnu_make.m4 3.96 KB
73ef4ff3   Hu Chunming   提交三方库
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  # ===========================================================================
  #    https://www.gnu.org/software/autoconf-archive/ax_check_gnu_make.html
  # ===========================================================================
  #
  # SYNOPSIS
  #
  #   AX_CHECK_GNU_MAKE([run-if-true],[run-if-false])
  #
  # 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 makefile variable `ifnGNUmake' is set to #, otherwise
  #       it is set to the empty string. This is useful for including a special
  #       features in a Makefile, which can be handled
  #       by other versions of make or to specify else like clause.
  #     * 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`.
  #     * Additionally if GNU Make is found, run shell code run-if-true
  #       else run shell code run-if-false.
  #
  #   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 $(DEPEND)
  #     @ifGNUmake@ else
  #     fallback code
  #     @ifGNUmake@ endif
  #
  #   Then configure.in would normally contain:
  #
  #     AX_CHECK_GNU_MAKE()
  #     AC_OUTPUT(Makefile)
  #
  #   Then perhaps to cause gnu make to override any other make, we could do
  #   something like this (note that GNU make always looks for GNUmakefile
  #   first):
  #
  #     if  ! test x$_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 12
  
  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 $(NF); }')
          break ;
        fi
      done ;])
  dnl If there was a GNU version, then set @ifGNUmake@ to the empty string, '#' otherwise
    AS_VAR_IF([_cv_gnu_make_command], [""], [AS_VAR_SET([ifGNUmake], ["#"])],   [AS_VAR_SET([ifGNUmake], [""])])
    AS_VAR_IF([_cv_gnu_make_command], [""], [AS_VAR_SET([ifnGNUmake], [""])],   [AS_VAR_SET([ifnGNUmake], ["#"])])
    AS_VAR_IF([_cv_gnu_make_command], [""], [AS_UNSET(ax_cv_gnu_make_command)], [AS_VAR_SET([ax_cv_gnu_make_command], [${_cv_gnu_make_command}])])
    AS_VAR_IF([_cv_gnu_make_command], [""],[$2],[$1])
    AC_SUBST([ifGNUmake])
    AC_SUBST([ifnGNUmake])
  ])