117 lines
3.6 KiB
Makefile
117 lines
3.6 KiB
Makefile
# $NetBSD: varmod-defined.mk,v 1.13 2022/08/24 20:22:10 rillig Exp $
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#
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# Tests for the :D variable modifier, which returns the given string
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# if the variable is defined. It is closely related to the :U modifier.
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# Force the test results to be independent of the default value of this
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# setting, which is 'yes' for NetBSD's usr.bin/make but 'no' for the bmake
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# distribution and pkgsrc/devel/bmake.
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.MAKE.SAVE_DOLLARS= yes
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DEF= defined
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.undef UNDEF
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# Since DEF is defined, the value of the expression is "value", not
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# "defined".
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#
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.if ${DEF:Dvalue} != "value"
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. error
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.endif
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# Since UNDEF is not defined, the "value" is ignored. Instead of leaving the
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# expression undefined, it is set to "", exactly to allow the expression to
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# be used in .if conditions. In this place, other undefined expressions
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# would generate an error message.
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# XXX: Ideally the error message would be "undefined variable", but as of
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# 2020-08-25 it is "Malformed conditional".
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#
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.if ${UNDEF:Dvalue} != ""
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. error
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.endif
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# The modifier text may contain plain text as well as expressions.
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#
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.if ${DEF:D<${DEF}>} != "<defined>"
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. error
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.endif
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# Special characters that would be interpreted differently can be escaped.
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# These are '}' (the closing character of the expression), ':', '$' and '\'.
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# Any other backslash sequences are preserved.
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#
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# The escaping rules for string literals in conditions are completely
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# different though. There, any character may be escaped using a backslash.
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#
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.if ${DEF:D \} \: \$ \\ \) \n } != " } : \$ \\ \\) \\n "
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. error
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.endif
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# Like in several other places in variable expressions, when
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# ApplyModifier_Defined calls Var_Parse, double dollars lead to a parse
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# error that is silently ignored. This makes all dollar signs disappear,
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# except for the last, which is a well-formed variable expression.
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#
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.if ${DEF:D$$$$$${DEF}} != "defined"
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. error
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.endif
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# Any other text is written without any further escaping. In contrast
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# to the :M modifier, parentheses and braces do not need to be nested.
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# Instead, the :D modifier is implemented sanely by parsing nested
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# expressions as such, without trying any shortcuts. See ApplyModifier_Match
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# for an inferior variant.
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#
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.if ${DEF:D!&((((} != "!&(((("
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. error
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.endif
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# The :D modifier is often used in combination with the :U modifier.
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# It does not matter in which order the :D and :U modifiers appear.
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.if ${UNDEF:Dyes:Uno} != no
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. error
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.endif
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.if ${UNDEF:Uno:Dyes} != no
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. error
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.endif
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.if ${DEF:Dyes:Uno} != yes
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. error
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.endif
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.if ${DEF:Uno:Dyes} != yes
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. error
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.endif
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# Since the variable with the empty name is never defined, the :D modifier
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# can be used to add comments in the middle of an expression. That
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# expression always evaluates to an empty string.
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.if ${:D This is a comment. } != ""
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. error
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.endif
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# TODO: Add more tests for parsing the plain text part, to cover each branch
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# of ApplyModifier_Defined.
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# The :D and :U modifiers behave differently from the :@var@ modifier in
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# that they preserve dollars in a ':=' assignment. This is because
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# ApplyModifier_Defined passes the emode unmodified to Var_Parse, unlike
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# ApplyModifier_Loop, which uses ParseModifierPart, which in turn removes
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# the keepDollar flag from emode.
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#
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# XXX: This inconsistency is documented nowhere.
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.MAKEFLAGS: -dv
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8_DOLLARS= $$$$$$$$
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VAR:= ${8_DOLLARS}
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VAR:= ${VAR:D${8_DOLLARS}}
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VAR:= ${VAR:@var@${8_DOLLARS}@}
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.MAKEFLAGS: -d0
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# Before var.c 1.1030 from 2022-08-24, the following expression caused an
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# out-of-bounds read when parsing the indirect ':D' modifier.
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M_U_backslash:= ${:UU\\}
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.if ${:${M_U_backslash}} != "\\"
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. error
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.endif
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all: .PHONY
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