varmod-assign.mk revision 1.12 
1# $NetBSD: varmod-assign.mk,v 1.12 2021/03/15 18:56:38 rillig Exp $
2#
3# Tests for the obscure ::= variable modifiers, which perform variable
4# assignments during evaluation, just like the = operator in C.
5
6all:	mod-assign
7all:	mod-assign-nested
8all:	mod-assign-empty
9all:	mod-assign-parse
10all:	mod-assign-shell-error
11
12mod-assign:
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}.
17
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}.
22
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}.
27
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
31	# RAN variable.
32	@echo $@: ${echo.1 echo.2 echo.3:L:@i@${RAN::!=${i:C,.*,&; & 1>\&2,:S,., ,g}}@} ran:${RAN}.
33
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}.
37
38mod-assign-nested:
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}
42
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}
46
47	# The same effects happen when the variables are defined elsewhere.
48	@echo $@: ${SINK3:Q}
49	@echo $@: ${SINK4:Q}
50SINK3:=	${1:?${THEN3::=then3${IT3::=t3}}:${ELSE3::=else3${IE3::=e3}}}${THEN3}${ELSE3}${IT3}${IE3}
51SINK4:=	${0:?${THEN4::=then4${IT4::=t4}}:${ELSE4::=else4${IE4::=e4}}}${THEN4}${ELSE4}${IT4}${IE4}
52
53mod-assign-empty:
54	# Assigning to the empty variable would obviously not work since that
55	# variable is write-protected.  Therefore it is rejected early with a
56	# "Bad modifier" message.
57	#
58	# XXX: The error message is hard to read since the variable name is
59	# empty.  This leads to a trailing space in the error message.
60	@echo $@: ${::=value}
61
62	# In this variant, it is not as obvious that the name of the
63	# expression is empty.  Assigning to it is rejected as well, with the
64	# same "Bad modifier" message.
65	#
66	# XXX: The error message is hard to read since the variable name is
67	# empty.  This leads to a trailing space in the error message.
68	@echo $@: ${:Uvalue::=overwritten}
69
70	# The :L modifier sets the value of the expression to its variable
71	# name.  The name of the expression is "VAR", therefore assigning to
72	# that variable works.
73	@echo $@: ${VAR:L::=overwritten} VAR=${VAR}
74
75mod-assign-parse:
76	# The modifier for assignment operators starts with a ':'.
77	# An 'x' after that is an invalid modifier.
78	@echo ${ASSIGN::x}	# 'x' is an unknown assignment operator
79
80	# When parsing an assignment operator fails because the operator is
81	# incomplete, make falls back to the SysV modifier.
82	@echo ${SYSV::=sysv\:x}${SYSV::x=:y}
83
84	@echo ${ASSIGN::=value	# missing closing brace
85
86mod-assign-shell-error:
87	# If the command succeeds, the variable is assigned.
88	@${SH_OK::!= echo word; true } echo ok=${SH_OK}
89
90	# If the command fails, the variable keeps its previous value.
91	@${SH_ERR::=previous}
92	@${SH_ERR::!= echo word; false } echo err=${SH_ERR}
93
94# XXX: The ::= modifier expands its right-hand side exactly once.
95# This differs subtly from normal assignments such as '+=' or '=', which copy
96# their right-hand side literally.
97APPEND.prev=		previous
98APPEND.var=		${APPEND.prev}
99APPEND.indirect=	indirect $${:Unot expanded}
100APPEND.dollar=		$${APPEND.indirect}
101.if ${APPEND.var::+=${APPEND.dollar}} != ""
102.  error
103.endif
104.if ${APPEND.var} != "previous indirect \${:Unot expanded}"
105.  error
106.endif
107
108
109# The assignment modifier can be used in a variable expression that is
110# enclosed in parentheses.  In such a case, parsing stops at the first ')',
111# not at the first '}'.
112VAR=	previous
113_:=	$(VAR::=current})
114.if ${VAR} != "current}"
115.  error
116.endif
117
118
119# Before var.c 1.888 from 2021-03-15, an expression using the modifier '::='
120# expanded its variable name once too often during evaluation.  This was only
121# relevant for variable names containing a '$' sign in their actual name, not
122# the usual VAR.${param}.
123.MAKEFLAGS: -dv
124param=		twice
125VARNAME=	VAR.$${param}	# Indirect variable name because of the '$',
126				# to avoid difficult escaping rules.
127
128${VARNAME}=	initial-value	# Sets 'VAR.${param}' to 'expanded'.
129.if defined(VAR.twice)		# At this point, the '$$' is not expanded.
130.  error
131.endif
132.if ${${VARNAME}::=assigned-value} # Here the variable name gets expanded once
133.  error			# too often.
134.endif
135.if defined(VAR.twice)
136.  error The variable name in the '::=' modifier is expanded once too often.
137.endif
138.if ${${VARNAME}} != "assigned-value"
139.  error
140.endif
141.MAKEFLAGS: -d0
142