1
 2A := a # comment
 3
 4ifdef $(A)
 5$(error FAIL)
 6else
 7$(info PASS)
 8endif
 9
10a := b
11ifdef $(A)
12$(info PASS)
13else
14$(error FAIL)
15endif
16
17ifdef a # comment
18$(info PASS)
19else
20$(error FAIL)
21endif