125 lines
4.3 KiB
Makefile
125 lines
4.3 KiB
Makefile
# $NetBSD: var-op-sunsh.mk,v 1.8 2021/04/04 10:13:09 rillig Exp $
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#
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# Tests for the :sh= variable assignment operator, which runs its right-hand
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# side through the shell. It is a seldom-used alternative to the !=
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# assignment operator, adopted from Sun make.
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.MAKEFLAGS: -dL # Enable sane error messages
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# This is the idiomatic form of the Sun shell assignment operator.
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# The assignment operator is directly preceded by the ':sh'.
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VAR:sh= echo colon-sh
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.if ${VAR} != "colon-sh"
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. error
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.endif
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# It is also possible to have whitespace around the :sh assignment
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# operator modifier.
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VAR :sh = echo colon-sh-spaced
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.if ${VAR} != "colon-sh-spaced"
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. error
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.endif
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# Until 2020-10-04, the ':sh' could even be followed by other characters.
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# This was neither documented by NetBSD make nor by Solaris make and was
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# an implementation error.
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#
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# Since 2020-10-04, this is a normal variable assignment using the '='
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# assignment operator.
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VAR:shell= echo colon-shell
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.if ${${:UVAR\:shell}} != "echo colon-shell"
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. error
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.endif
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# Several colons can syntactically appear in a variable name.
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# Until 2020-10-04, the last of them was interpreted as the ':sh'
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# assignment operator.
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#
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# Since 2020-10-04, the colons are part of the variable name.
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VAR:shoe:shore= echo two-colons
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.if ${${:UVAR\:shoe\:shore}} != "echo two-colons"
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. error
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.endif
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# Until 2020-10-04, the following expression was wrongly marked as
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# a parse error. This was because the parser for variable assignments
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# just looked for the previous ":sh", without taking any contextual
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# information into account.
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#
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# There are two different syntactical elements that look exactly the same:
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# The variable modifier ':sh' and the assignment operator modifier ':sh'.
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# Intuitively this variable name contains the variable modifier, but until
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# 2020-10-04, the parser regarded it as an assignment operator modifier, in
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# Parse_Var.
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VAR.${:Uecho 123:sh}= ok-123
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.if ${VAR.123} != "ok-123"
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. error
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.endif
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# Same pattern here. Until 2020-10-04, the ':sh' inside the nested expression
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# was taken for the :sh assignment operator modifier, even though it was
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# escaped by a backslash.
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VAR.${:U echo\:shell}= ok-shell
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.if ${VAR.${:U echo\:shell}} != "ok-shell"
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. error
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.endif
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# Until 2020-10-04, the word 'shift' was also affected since it starts with
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# ':sh'.
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VAR.key:shift= Shift
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.if ${${:UVAR.key\:shift}} != "Shift"
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. error
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.endif
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# Just for fun: The code in Parse_IsVar allows for multiple appearances of
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# the ':sh' assignment operator modifier. Let's see what happens ...
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#
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# Well, the end result is correct but the way until there is rather
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# adventurous. This only works because the parser replaces each and every
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# whitespace character that is not nested with '\0' (see Parse_Var).
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# The variable name therefore ends before the first ':sh', and the last
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# ':sh' turns the assignment operator into the shell command evaluation.
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# Parse_Var completely trusts Parse_IsVar to properly verify the syntax.
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#
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# The ':sh' is the only word that may occur between the variable name and
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# the assignment operator at nesting level 0. All other words would lead
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# to a parse error since the left-hand side of an assignment must be
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# exactly one word.
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VAR :sh :sh :sh :sh= echo multiple
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.if ${VAR} != "multiple"
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. error
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.endif
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# The word ':sh' is not the only thing that can occur after a variable name.
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# Since the parser just counts braces and parentheses instead of properly
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# expanding nested expressions, the token ' :sh' can be used to add arbitrary
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# text between the variable name and the assignment operator, it just has to
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# be enclosed in braces or parentheses.
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VAR :sh(Put a comment here)= comment in parentheses
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.if ${VAR} != "comment in parentheses"
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. error
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.endif
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# The unintended comment can include multiple levels of nested braces and
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# parentheses, they don't even need to be balanced since they are only
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# counted by Parse_IsVar and ignored by Parse_Var.
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VAR :sh{Put}((((a}{comment}}}}{here}= comment in braces
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.if ${VAR} != "comment in braces"
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. error
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.endif
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# Syntactically, the ':sh' modifier can be combined with the '+=' assignment
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# operator. In such a case the ':sh' modifier is silently ignored.
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#
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# XXX: This combination should not be allowed at all.
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VAR= one
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VAR :sh += echo two
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.if ${VAR} != "one echo two"
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. error ${VAR}
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.endif
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# TODO: test VAR:sh!=command
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all:
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@:;
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