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