1
 2# We want to allow both empty commands _and_ commands that resolve to empty.
 3EMPTY =
 4
 5.PHONY: all a1 a2 a3 a4
 6all: a1 a2 a3 a4
 7
 8a1:;
 9a2:
10	
11a3:;$(EMPTY)
12a4:
13	$(EMPTY)
14
15# Non-empty lines that expand to nothing should also be ignored.
16STR =     # Some spaces
17TAB =   	  # A TAB and some spaces
18
19$(STR)
20
21$(STR) $(TAB)