[perl #81136] Capture reference doesn't work in lookahead assertions

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# New Ticket Created by  Jörg Walter 
# Please include the string:  [perl #81136]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=81136 >


This example program explains it all:

grammar test {
        token a { a };
        token b { b };
        token TOP { <a><b><before $<a>> };
};

if (test.parse("abc")) {
        say "bug!"
} else {
        say "correct."
}

grammar test2 is test {
        token TOP { <a><b><before $<a>>$<a> };
}

if (test2.parse("abc")) {
        say "bug!"
} else {
        say "correct."
}

grammar test3 is test {
        token TOP { <a><b><before {say 'have '~$<a>}$<a>> };
}

test3.parse("abc");


On rakudo star 2010.11, it prints
bug!
correct
have

Modifying the grammars to use positional captures yields the same results.

-- 
Mit freundlichen Grüßen,

        Jörg Walter