m4/ax_append_flag.m4

# ===========================================================================
#      https://www.gnu.org/software/autoconf-archive/ax_append_flag.html
# ===========================================================================
#
# SYNOPSIS
#
#   AX_APPEND_FLAG(FLAG, [FLAGS-VARIABLE])
#
# DESCRIPTION
#
#   FLAG is appended to the FLAGS-VARIABLE shell variable, with a space
#   added in between.
#
#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
#   CFLAGS) is used.  FLAGS-VARIABLE is not changed if it already contains
#   FLAG.  If FLAGS-VARIABLE is unset in the shell, it is set to exactly
#   FLAG.
#
#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION.
#
# LICENSE
#
#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@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 <https://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 7

AC_DEFUN([AX_APPEND_FLAG],
[dnl
AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_SET_IF
AS_VAR_PUSHDEF([FLAGS], [m4_default($2,_AC_LANG_PREFIX[FLAGS])])
AS_VAR_SET_IF(FLAGS,[
  AS_CASE([" AS_VAR_GET(FLAGS) "],
    [*" $1 "*], [AC_RUN_LOG([: FLAGS already contains $1])],
    [
     AS_VAR_APPEND(FLAGS,[" $1"])
     AC_RUN_LOG([: FLAGS="$FLAGS"])
    ])
  ],
  [
  AS_VAR_SET(FLAGS,[$1])
  AC_RUN_LOG([: FLAGS="$FLAGS"])
  ])
AS_VAR_POPDEF([FLAGS])dnl
])dnl AX_APPEND_FLAG