#   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 <http://www.gnu.org/licenses/>.
#
# test expression evaluation with unset variables
set -u

( echo $(( a > 4 )) ; echo after 1 )	# error
( echo $(( a[0] > 4 )); echo after 2)	# error

set +u
( echo $(( a > 4 )) ; echo after 3 $? )
( echo $(( a[0] > 4 )); echo after 4 $?)

# this is a recursion stack error
a=b
b=a
echo $(( a + 7 ))

# make sure command printing works for arithmetic expansions and commands
set -x
var=42

echo $(( $var ))
echo $?

echo $(( $null ))
echo $?

(( $var ))
echo $?

(( $null ))
echo $?

set +x

# invalid expressions in different cases
x=4+
declare -i x
x+=7 y=4
echo x = $x y = $y