git/mergetools/meld

diff_cmd () {
	"$merge_tool_path" "$LOCAL" "$REMOTE"
}

merge_cmd () {
	if test -z "${meld_has_output_option:+set}"
	then
		check_meld_for_output_version
	fi
	touch "$BACKUP"
	if test "$meld_has_output_option" = true
	then
		"$merge_tool_path" --output "$MERGED" \
			"$LOCAL" "$BASE" "$REMOTE"
	else
		"$merge_tool_path" "$LOCAL" "$MERGED" "$REMOTE"
	fi
	check_unchanged
}

# Check whether we should use 'meld --output <file>'
check_meld_for_output_version () {
	meld_path="$(git config mergetool.meld.path)"
	meld_path="${meld_path:-meld}"

	if meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
	then
		: use configured value
	elif "$meld_path" --help 2>&1 |
		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
	then
		: old ones mention --output and new ones just say OPTION...
		meld_has_output_option=true
	else
		meld_has_output_option=false
	fi
}