79 lines
3.1 KiB
Makefile
79 lines
3.1 KiB
Makefile
# $NetBSD: varmod-remember.mk,v 1.9 2023/02/09 22:21:57 rillig Exp $
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#
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# Tests for the :_ modifier, which saves the current expression value
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# in the _ variable or another, to be used later again.
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# The ':_' modifier is typically used in situations where the value of an
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# expression is needed at the same time as a sequence of numbers. In these
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# cases, the value of the expression is saved in the temporary variable '_',
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# from where it is taken later in the same expression.
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ABC= ${A B C:L:_:range:@i@$i=${_:[$i]}@}
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DEF= ${D E F:L:_:range:@i@$i=${_:[$i]}@}
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GHI= ${G H I:L:_:range:@i@$i=${_:[$i]}@}
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ABC.global:= ${ABC} # is evaluated in the global scope
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.if ${ABC.global} != "1=A 2=B 3=C"
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. error
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.endif
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.if ${DEF} != "1=D 2=E 3=F" # is evaluated in the command line scope
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. error
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.endif
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# Before var.c 1.1040 from 2023-02-09, the temporary variable '_' was placed
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# in the scope of the current evaluation, which meant that after the first
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# ':_' modifier had been evaluated in command line scope, all further
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# evaluations in global scope could not overwrite the variable '_' anymore,
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# as the command line scope takes precedence over the global scope.
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# The expression ${GHI} therefore evaluated to '1=D 2=E 3=F', reusing the
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# value of '_' from the previous evaluation in command line scope.
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GHI.global:= ${GHI} # is evaluated in the global scope
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.if ${GHI.global} != "1=G 2=H 3=I"
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. error
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.endif
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# In the parameterized form, having the variable name on the right side of
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# the = assignment operator looks confusing. In almost all other situations,
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# the variable name is on the left-hand side of the = operator, therefore
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# '_=SAVED' looks like it would copy 'SAVED' to '_'. Luckily, this modifier
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# is only rarely needed.
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.if ${1 2 3:L:@var@${var:_=SAVED:}@} != "1 2 3"
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. error
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.elif ${SAVED} != "3"
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. error
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.endif
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# The ':_' modifier takes a variable name as optional argument. Before var.c
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# 1.867 from 2021-03-14, this variable name could refer to other variables,
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# such as in 'VAR.$p'. It was not possible to refer to 'VAR.${param}' though,
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# as that form caused a parse error. The cause for the parse error in
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# '${...:_=VAR.${param}}' is that the variable name is parsed in an ad-hoc
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# manner, stopping at the first ':', ')' or '}', without taking any nested
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# expressions into account. Due to this inconsistency that short expressions
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# are possible but long expressions aren't, the name of the temporary variable
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# is no longer expanded.
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#
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# TODO: Warn about the unusual variable name '$S'.
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S= INDIRECT_VARNAME
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.if ${value:L:@var@${var:_=$S}@} != "value"
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. error
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.elif defined(INDIRECT_VARNAME)
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. error
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.endif
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# When a variable using ':_' refers to another variable that also uses ':_',
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# the value of the temporary variable '_' from the inner expression leaks into
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# the evaluation of the outer expression. If the expressions were evaluated
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# independently, the last word of the result would be outer_='outer' instead.
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INNER= ${inner:L:_:@i@$i inner_='$_'@}
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OUTER= ${outer:L:_:@o@$o ${INNER} outer_='$_'@}
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.if ${OUTER} != "outer inner inner_='inner' outer_='inner'"
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.endif
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all:
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