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parse-var.mk revision 1.2 
      1  1.2  rillig # $NetBSD: parse-var.mk,v 1.2 2022/08/06 21:26:05 rillig Exp $
      2  1.2  rillig #
      3  1.2  rillig # Tests for parsing variable expressions.
      4  1.1  rillig 
      5  1.1  rillig .MAKEFLAGS: -dL
      6  1.1  rillig 
      7  1.2  rillig # In variable assignments, there may be spaces in the middle of the left-hand
      8  1.2  rillig # side of the assignment, but only if they occur inside variable expressions.
      9  1.2  rillig # Leading spaces (but not tabs) are possible but unusual.
     10  1.2  rillig # Trailing spaces are common in some coding styles, others omit them.
     11  1.1  rillig VAR.${:U param }=	value
     12  1.1  rillig .if ${VAR.${:U param }} != "value"
     13  1.1  rillig .  error
     14  1.1  rillig .endif
     15  1.1  rillig 
     16  1.2  rillig 
     17  1.2  rillig # As of var.c 1.1027 from 2022-08-05, the exact way of parsing an expression
     18  1.2  rillig # depends on whether the expression is actually evaluated or merely parsed.
     19  1.2  rillig #
     20  1.2  rillig # If it is evaluated, nested expressions are parsed correctly, parsing each
     21  1.2  rillig # modifier according to its exact definition.  If the expression is merely
     22  1.2  rillig # parsed but not evaluated (because its value would not influence the outcome
     23  1.2  rillig # of the condition), and the expression contains a modifier, and that modifier
     24  1.2  rillig # contains a nested expression, the nested expression is not parsed
     25  1.2  rillig # correctly.  Instead, make only counts the opening and closing delimiters,
     26  1.2  rillig # which fails for nested modifiers with unbalanced braces.
     27  1.2  rillig #
     28  1.2  rillig # See ParseModifierPartDollar.
     29  1.2  rillig 
     30  1.2  rillig #.MAKEFLAGS: -dcpv
     31  1.2  rillig # Keep these braces outside the conditions below, to keep them simple to
     32  1.2  rillig # understand.  If the BRACE_PAIR had been replaced with ':U{}', the '}' would
     33  1.2  rillig # have to be escaped, but not the '{'.  This asymmetry would have made the
     34  1.2  rillig # example even more complicated to understand.
     35  1.2  rillig BRACE_PAIR=	{}
     36  1.2  rillig # In this test word, the '{{}' in the middle will be replaced.
     37  1.2  rillig BRACE_GROUP=	{{{{}}}}
     38  1.2  rillig 
     39  1.2  rillig # The inner ':S' modifier turns the word '{}' into '{{}'.
     40  1.2  rillig # The outer ':S' modifier then replaces '{{}' with '<lbraces>'.
     41  1.2  rillig # In the first case, the outer expression is relevant and is parsed correctly.
     42  1.2  rillig .if 1 && ${BRACE_GROUP:S,${BRACE_PAIR:S,{,{{,},<lbraces>,}
     43  1.2  rillig .endif
     44  1.2  rillig # In the second case, the outer expression is irrelevant.  In this case, in
     45  1.2  rillig # the parts of the outer ':S' modifier, make only counts the braces, and since
     46  1.2  rillig # the inner expression '${:U...}' contains more '{' than '}', parsing fails.
     47  1.2  rillig .if 0 && ${BRACE_GROUP:S,${BRACE_PAIR:S,{,{{,},<lbraces>,}
     48  1.2  rillig .endif
     49  1.2  rillig #.MAKEFLAGS: -d0
     50  1.2  rillig 
     51  1.2  rillig 
     52  1.2  rillig all: .PHONY
     53