blob: 5a3375cbbfb89f018f3f352a203a853dc597949e (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
|
# $NetBSD: cmdline-undefined.mk,v 1.2 2020/11/04 04:49:33 rillig Exp $
#
# Tests for undefined variable expressions in the command line.
all:
# When the command line is parsed, variable assignments using the
# '=' assignment operator do get their variable name expanded
# (which probably occurs rarely in practice, if at all), but their
# variable value is not expanded, as usual.
#
@echo 'The = assignment operator'
@${.MAKE} -f ${MAKEFILE} print-undefined \
CMDLINE='Undefined is $${UNDEFINED}.'
@echo
# The interesting case is using the ':=' assignment operator, which
# expands its right-hand side. But only those variables that are
# defined.
@echo 'The := assignment operator'
@${.MAKE} -f ${MAKEFILE} print-undefined \
CMDLINE:='Undefined is $${UNDEFINED}.'
@echo
.if make(print-undefined)
.MAKEFLAGS: MAKEFLAGS_ASSIGN='Undefined is $${UNDEFINED}.'
.MAKEFLAGS: MAKEFLAGS_SUBST:='Undefined is $${UNDEFINED}.'
.info From the command line: ${CMDLINE}
.info From .MAKEFLAGS '=': ${MAKEFLAGS_ASSIGN}
.info From .MAKEFLAGS ':=': ${MAKEFLAGS_SUBST}
UNDEFINED?= now defined
.info From the command line: ${CMDLINE}
.info From .MAKEFLAGS '=': ${MAKEFLAGS_ASSIGN}
.info From .MAKEFLAGS ':=': ${MAKEFLAGS_SUBST}
print-undefined:
.endif
|