t/ax/is

#! /bin/sh
# Copyright (C) 2012-2018 Free Software Foundation, Inc.
#
# 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 2, 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/>.

# Test that two whitespace-separated lists are equal.
# Assumes the two lists are passed on the command line separated by
# a '==' string.
# This script is useful to test equality of lists in makefile rules,
# in the face of variables defined through line-continuations,
# automake rewrites and expansions of empty variables.

# NOTE: keep this file Bourne-compatible, for the sake of systems with
#       non-POSIX /bin/sh (like Solaris).

set -e
set -u

# Initialize before unsetting, for shells (like older bash or Solaris
# ksh) that fail to unset variables that are already unset.
exp= got=; unset exp got
seen_eqeq=no
while test $# -gt 0; do
  if test x"$1" = x"=="; then
    if test $seen_eqeq = no; then
      seen_eqeq=yes
    else
      echo "$0: more than one '==' argument seen on command line" >&2
      exit 2
    fi
  else
    if test $seen_eqeq = no; then
      got=${got+"$got "}$1
    else
      exp=${exp+"$exp "}$1
    fi
  fi
  shift
done

if test $seen_eqeq = no; then
  echo "$0: no '==' argument seen on command line" >&2
  exit 2
fi

test x"${exp-}" = x"${got-}"