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1b65f0bd2b
o allow env var MAKE_OBJDIR_CHECK_WRITABLE=no to skip writable checks in InitObjdir. Explicit .OBJDIR target always allows read-only directory. o Fix building and unit-tests on non-BSD. o More code cleanup and refactoring. o More unit tests
32 lines
1 KiB
Makefile
32 lines
1 KiB
Makefile
# $NetBSD: cond-late.mk,v 1.3 2020/11/15 14:07:53 rillig Exp $
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#
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# Using the :? modifier, variable expressions can contain conditional
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# expressions that are evaluated late, at expansion time.
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#
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# Any variables appearing in these
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# conditions are expanded before parsing the condition. This is
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# different from many other places.
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#
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# Because of this, variables that are used in these lazy conditions
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# should not contain double-quotes, or the parser will probably fail.
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#
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# They should also not contain operators like == or <, since these are
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# actually interpreted as these operators. This is demonstrated below.
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#
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all: cond-literal
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COND.true= "yes" == "yes"
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COND.false= "yes" != "yes"
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# If the order of evaluation were to change to first parse the condition
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# and then expand the variables, the output would change from the
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# current "yes no" to "yes yes", since both variables are non-empty.
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cond-literal:
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@echo ${ ${COND.true} :?yes:no}
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@echo ${ ${COND.false} :?yes:no}
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VAR+= ${${UNDEF} != "no":?:}
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.if empty(VAR:Mpattern)
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.endif
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