dba7b0ef92
Changes of interest
o unit-tests: use private TMPDIR to avoid errors from other users
o avoid strdup in mkTempFile
o always use vfork
o job.c: do not create empty shell files in jobs mode
reduce unnecessary calls to waitpid
o cond.c: fix debug output for comparison operators in conditionals
91 lines
3.4 KiB
Makefile
Executable File
91 lines
3.4 KiB
Makefile
Executable File
# $NetBSD: varmod-match-escape.mk,v 1.6 2021/02/01 22:36:28 rillig Exp $
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#
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# As of 2020-08-01, the :M and :N modifiers interpret backslashes differently,
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# depending on whether there was a variable expression somewhere before the
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# first backslash or not. See ApplyModifier_Match, "copy = TRUE".
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#
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# Apart from the different and possibly confusing debug output, there is no
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# difference in behavior. When parsing the modifier text, only \{, \} and \:
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# are unescaped, and in the pattern matching these have the same meaning as
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# their plain variants '{', '}' and ':'. In the pattern matching from
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# Str_Match, only \*, \? or \[ would make a noticeable difference.
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.MAKEFLAGS: -dcv
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SPECIALS= \: : \\ * \*
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.if ${SPECIALS:M${:U}\:} != ${SPECIALS:M\:${:U}}
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. warning unexpected
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.endif
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# And now both cases combined: A single modifier with both an escaped ':'
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# as well as a variable expression that expands to a ':'.
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#
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# XXX: As of 2020-11-01, when an escaped ':' occurs before the variable
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# expression, the whole modifier text is subject to unescaping '\:' to ':',
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# before the variable expression is expanded. This means that the '\:' in
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# the variable expression is expanded as well, turning ${:U\:} into a simple
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# ${:U:}, which silently expands to an empty string, instead of generating
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# an error message.
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#
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# XXX: As of 2020-11-01, the modifier on the right-hand side of the
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# comparison is parsed differently though. First, the variable expression
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# is parsed, resulting in ':' and needSubst=TRUE. After that, the escaped
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# ':' is seen, and this time, copy=TRUE is not executed but stays copy=FALSE.
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# Therefore the escaped ':' is kept as-is, and the final pattern becomes
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# ':\:'.
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#
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# If ApplyModifier_Match had used the same parsing algorithm as Var_Subst,
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# both patterns would end up as '::'.
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#
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VALUES= : :: :\:
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.if ${VALUES:M\:${:U\:}} != ${VALUES:M${:U\:}\:}
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. warning XXX: Oops
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.endif
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.MAKEFLAGS: -d0
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# XXX: As of 2020-11-01, unlike all other variable modifiers, a '$' in the
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# :M and :N modifiers is written as '$$', not as '\$'. This is confusing,
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# undocumented and hopefully not used in practice.
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.if ${:U\$:M$$} != "\$"
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. error
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.endif
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# XXX: As of 2020-11-01, unlike all other variable modifiers, '\$' is not
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# parsed as an escaped '$'. Instead, ApplyModifier_Match first scans for
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# the ':' at the end of the modifier, which results in the pattern '\$'.
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# No unescaping takes place since the pattern neither contained '\:' nor
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# '\{' nor '\}'. But the text is expanded, and a lonely '$' at the end
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# is silently discarded. The resulting expanded pattern is thus '\', that
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# is a single backslash.
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.if ${:U\$:M\$} != ""
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. error
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.endif
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# In lint mode, the case of a lonely '$' is covered with an error message.
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.MAKEFLAGS: -dL
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.if ${:U\$:M\$} != ""
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. error
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.endif
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# The control flow of the pattern parser depends on the actual string that
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# is being matched. There needs to be either a test that shows a difference
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# in behavior, or a proof that the behavior does not depend on the actual
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# string.
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#
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# TODO: Str_Match("a-z]", "[a-z]")
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# TODO: Str_Match("012", "[0-]]")
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# TODO: Str_Match("0]", "[0-]]")
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# TODO: Str_Match("1]", "[0-]]")
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# TODO: Str_Match("[", "[[]")
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# TODO: Str_Match("]", "[]")
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# TODO: Str_Match("]", "[[-]]")
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# In brackets, the backslash is just an ordinary character.
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# Outside brackets, it is an escape character for a few special characters.
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# TODO: Str_Match("\\", "[\\-]]")
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# TODO: Str_Match("-]", "[\\-]]")
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all:
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@:;
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