1 # $NetBSD: cond-token-var.mk,v 1.4 2020/10/24 08:46:08 rillig Exp $
3 # Tests for variables in .if conditions.
7 # A defined variable may appear on either side of the comparison.
14 # A variable that appears on the left-hand side must be defined.
15 .if ${UNDEF} == ${DEF}
19 # A variable that appears on the right-hand side must be defined.
20 .if ${DEF} == ${UNDEF}
24 # A defined variable may appear as an expression of its own.
28 # An undefined variable generates a warning.
32 # The :U modifier turns an undefined variable into an ordinary expression.