142 lines
5.3 KiB
Makefile
142 lines
5.3 KiB
Makefile
# $NetBSD: varmod-assign.mk,v 1.12 2021/03/15 18:56:38 rillig Exp $
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#
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# Tests for the obscure ::= variable modifiers, which perform variable
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# assignments during evaluation, just like the = operator in C.
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all: mod-assign
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all: mod-assign-nested
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all: mod-assign-empty
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all: mod-assign-parse
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all: mod-assign-shell-error
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mod-assign:
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# The ::?= modifier applies the ?= assignment operator 3 times.
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# The ?= operator only has an effect for the first time, therefore
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# the variable FIRST ends up with the value 1.
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@echo $@: ${1 2 3:L:@i@${FIRST::?=$i}@} first=${FIRST}.
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# The ::= modifier applies the = assignment operator 3 times.
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# The = operator overwrites the previous value, therefore the
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# variable LAST ends up with the value 3.
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@echo $@: ${1 2 3:L:@i@${LAST::=$i}@} last=${LAST}.
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# The ::+= modifier applies the += assignment operator 3 times.
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# The += operator appends 3 times to the variable, therefore
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# the variable APPENDED ends up with the value "1 2 3".
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@echo $@: ${1 2 3:L:@i@${APPENDED::+=$i}@} appended=${APPENDED}.
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# The ::!= modifier applies the != assignment operator 3 times.
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# The side effects of the shell commands are visible in the output.
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# Just as with the ::= modifier, the last value is stored in the
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# RAN variable.
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@echo $@: ${echo.1 echo.2 echo.3:L:@i@${RAN::!=${i:C,.*,&; & 1>\&2,:S,., ,g}}@} ran:${RAN}.
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# The assignments happen in the global scope and thus are
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# preserved even after the shell command has been run.
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@echo $@: global: ${FIRST:Q}, ${LAST:Q}, ${APPENDED:Q}, ${RAN:Q}.
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mod-assign-nested:
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# The condition "1" is true, therefore THEN1 gets assigned a value,
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# and IT1 as well. Nothing surprising here.
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@echo $@: ${1:?${THEN1::=then1${IT1::=t1}}:${ELSE1::=else1${IE1::=e1}}}${THEN1}${ELSE1}${IT1}${IE1}
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# The condition "0" is false, therefore ELSE1 gets assigned a value,
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# and IE1 as well. Nothing surprising here as well.
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@echo $@: ${0:?${THEN2::=then2${IT2::=t2}}:${ELSE2::=else2${IE2::=e2}}}${THEN2}${ELSE2}${IT2}${IE2}
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# The same effects happen when the variables are defined elsewhere.
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@echo $@: ${SINK3:Q}
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@echo $@: ${SINK4:Q}
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SINK3:= ${1:?${THEN3::=then3${IT3::=t3}}:${ELSE3::=else3${IE3::=e3}}}${THEN3}${ELSE3}${IT3}${IE3}
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SINK4:= ${0:?${THEN4::=then4${IT4::=t4}}:${ELSE4::=else4${IE4::=e4}}}${THEN4}${ELSE4}${IT4}${IE4}
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mod-assign-empty:
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# Assigning to the empty variable would obviously not work since that
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# variable is write-protected. Therefore it is rejected early with a
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# "Bad modifier" message.
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#
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# XXX: The error message is hard to read since the variable name is
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# empty. This leads to a trailing space in the error message.
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@echo $@: ${::=value}
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# In this variant, it is not as obvious that the name of the
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# expression is empty. Assigning to it is rejected as well, with the
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# same "Bad modifier" message.
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#
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# XXX: The error message is hard to read since the variable name is
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# empty. This leads to a trailing space in the error message.
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@echo $@: ${:Uvalue::=overwritten}
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# The :L modifier sets the value of the expression to its variable
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# name. The name of the expression is "VAR", therefore assigning to
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# that variable works.
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@echo $@: ${VAR:L::=overwritten} VAR=${VAR}
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mod-assign-parse:
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# The modifier for assignment operators starts with a ':'.
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# An 'x' after that is an invalid modifier.
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@echo ${ASSIGN::x} # 'x' is an unknown assignment operator
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# When parsing an assignment operator fails because the operator is
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# incomplete, make falls back to the SysV modifier.
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@echo ${SYSV::=sysv\:x}${SYSV::x=:y}
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@echo ${ASSIGN::=value # missing closing brace
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mod-assign-shell-error:
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# If the command succeeds, the variable is assigned.
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@${SH_OK::!= echo word; true } echo ok=${SH_OK}
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# If the command fails, the variable keeps its previous value.
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@${SH_ERR::=previous}
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@${SH_ERR::!= echo word; false } echo err=${SH_ERR}
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# XXX: The ::= modifier expands its right-hand side exactly once.
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# This differs subtly from normal assignments such as '+=' or '=', which copy
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# their right-hand side literally.
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APPEND.prev= previous
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APPEND.var= ${APPEND.prev}
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APPEND.indirect= indirect $${:Unot expanded}
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APPEND.dollar= $${APPEND.indirect}
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.if ${APPEND.var::+=${APPEND.dollar}} != ""
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. error
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.endif
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.if ${APPEND.var} != "previous indirect \${:Unot expanded}"
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. error
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.endif
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# The assignment modifier can be used in a variable expression that is
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# enclosed in parentheses. In such a case, parsing stops at the first ')',
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# not at the first '}'.
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VAR= previous
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_:= $(VAR::=current})
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.if ${VAR} != "current}"
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. error
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.endif
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# Before var.c 1.888 from 2021-03-15, an expression using the modifier '::='
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# expanded its variable name once too often during evaluation. This was only
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# relevant for variable names containing a '$' sign in their actual name, not
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# the usual VAR.${param}.
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.MAKEFLAGS: -dv
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param= twice
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VARNAME= VAR.$${param} # Indirect variable name because of the '$',
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# to avoid difficult escaping rules.
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${VARNAME}= initial-value # Sets 'VAR.${param}' to 'expanded'.
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.if defined(VAR.twice) # At this point, the '$$' is not expanded.
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. error
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.endif
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.if ${${VARNAME}::=assigned-value} # Here the variable name gets expanded once
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. error # too often.
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.endif
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.if defined(VAR.twice)
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. error The variable name in the '::=' modifier is expanded once too often.
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.endif
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.if ${${VARNAME}} != "assigned-value"
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. error
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.endif
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.MAKEFLAGS: -d0
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