1MAKEVER:=$(shell make --version | grep "Make [0-9]" | sed -E 's/.*Make ([0-9]).*/\1/')
 2
 3ifeq ($(MAKEVER),4)
 4# A variable name with space is invalid on GNU make 4.
 5all:
 6	echo PASS
 7else
 8varname_with_ws:=hello, world!
 9$(varname_with_ws):=PASS
10foo bar = PASS2
11all:
12	echo $(hello, world!)
13	echo $(foo bar)
14endif