1 # $NetBSD: opt-define.mk,v 1.3 2022/01/23 16:09:38 rillig Exp $
3 # Tests for the -D command line option, which defines global variables to the
4 # value 1, like in the C preprocessor.
8 # The variable has the exact value "1", not "1.0".
13 # The variable can be overwritten by assigning another value to it. This
14 # would not be possible if the variable had been specified on the command line
15 # as 'VAR=1' instead of '-DVAR'.
17 .if ${VAR} != "overwritten"
21 # The variable can be undefined. If the variable had been defined in the
22 # "Internal" scope instead, undefining it would have no effect.