1 # $NetBSD: varmod-assign.mk,v 1.6 2020/08/25 21:16:53 rillig Exp $
3 # Tests for the obscure ::= variable modifiers, which perform variable
4 # assignments during evaluation, just like the = operator in C.
10 all: mod-assign-shell-error
13 # The ::?= modifier applies the ?= assignment operator 3 times.
14 # The ?= operator only has an effect for the first time, therefore
15 # the variable FIRST ends up with the value 1.
16 @echo $@: ${1 2 3:L:@i@${FIRST::?=$i}@} first=${FIRST}.
18 # The ::= modifier applies the = assignment operator 3 times.
19 # The = operator overwrites the previous value, therefore the
20 # variable LAST ends up with the value 3.
21 @echo $@: ${1 2 3:L:@i@${LAST::=$i}@} last=${LAST}.
23 # The ::+= modifier applies the += assignment operator 3 times.
24 # The += operator appends 3 times to the variable, therefore
25 # the variable APPENDED ends up with the value "1 2 3".
26 @echo $@: ${1 2 3:L:@i@${APPENDED::+=$i}@} appended=${APPENDED}.
28 # The ::!= modifier applies the != assignment operator 3 times.
29 # The side effects of the shell commands are visible in the output.
30 # Just as with the ::= modifier, the last value is stored in the
32 @echo $@: ${echo.1 echo.2 echo.3:L:@i@${RAN::!=${i:C,.*,&; & 1>\&2,:S,., ,g}}@} ran:${RAN}.
34 # The assignments happen in the global scope and thus are
35 # preserved even after the shell command has been run.
36 @echo $@: global: ${FIRST:Q}, ${LAST:Q}, ${APPENDED:Q}, ${RAN:Q}.
39 # The condition "1" is true, therefore THEN1 gets assigned a value,
40 # and IT1 as well. Nothing surprising here.
41 @echo $@: ${1:?${THEN1::=then1${IT1::=t1}}:${ELSE1::=else1${IE1::=e1}}}${THEN1}${ELSE1}${IT1}${IE1}
43 # The condition "0" is false, therefore ELSE1 gets assigned a value,
44 # and IE1 as well. Nothing surprising here as well.
45 @echo $@: ${0:?${THEN2::=then2${IT2::=t2}}:${ELSE2::=else2${IE2::=e2}}}${THEN2}${ELSE2}${IT2}${IE2}
47 # The same effects happen when the variables are defined elsewhere.
50 SINK3:= ${1:?${THEN3::=then3${IT3::=t3}}:${ELSE3::=else3${IE3::=e3}}}${THEN3}${ELSE3}${IT3}${IE3}
51 SINK4:= ${0:?${THEN4::=then4${IT4::=t4}}:${ELSE4::=else4${IE4::=e4}}}${THEN4}${ELSE4}${IT4}${IE4}
54 # Assigning to the empty variable would obviously not work since that variable
55 # is write-protected. Therefore it is rejected early as a "bad modifier".
57 @echo $@: ${:Uvalue::=overwritten}
59 # The :L modifier sets the variable's value to its name.
60 # Since the name is still "VAR", assigning to that variable works.
61 @echo $@: ${VAR:L::=overwritten} VAR=${VAR}
64 # The modifier for assignment operators starts with a ':'.
65 # An 'x' after that is an invalid modifier.
66 @echo ${ASSIGN::x} # 'x' is an unknown assignment operator
68 # When parsing an assignment operator fails because the operator is
69 # incomplete, make falls back to the SysV modifier.
70 @echo ${SYSV::=sysv\:x}${SYSV::x=:y}
72 @echo ${ASSIGN::=value # missing closing brace
74 mod-assign-shell-error:
75 # If the command succeeds, the variable is assigned.
76 @${SH_OK::!= echo word; true } echo ok=${SH_OK}
78 # If the command fails, the variable keeps its previous value.
79 # FIXME: the error message says: "previous" returned non-zero status
81 @${SH_ERR::!= echo word; false } echo err=${SH_ERR}