From @masak

<cognominal> nom​: (grammar { token TOP { <a>? $<b>='b' }; token a {
a } }).parse​: 'ab'; say $/<b>.keys;
<p6eval> nom 4130f6​: OUTPUT«a␤»
<cognominal> nom​: (grammar { token TOP { <a> $<b>='b' }; token a {
a } }).parse​: 'ab'; say $/<b>.keys;
<p6eval> nom 4130f6​: OUTPUT«␤»
<cognominal> jnthn, this does not make any sense to me that $/<b>.keys
returns anything different than a void Parcel
<cognominal> should I file a bug?
<moritz> nom​: (grammar { token TOP { <a> $<b>='b' }; token a { a }
}).parse​: 'ab'; say $/<b>.keys.WHAT;
<p6eval> nom 4130f6​: OUTPUT«List()␤»
<moritz> cognominal​: it's returns an empty List, not an empty Parcel.
Is that your problem?
<cognominal> see the first example, it prints "a\n".
<cognominal> I don't care if it is a parcel or a list. Whatever it is
should be empty.
<moritz> agreed
<cognominal> it does not happen when I delete the '?' suffix.
<moritz> though of course the ? quantifier on <a> should not affect $<b>
<cognominal> yes, that's my point.
<moritz> agreed. Bug it is.
<cognominal> it took me a while to golf it. Probably because my code
hits other bugs as well.
* masak submits rakudobug

From @cognominal

$ perl6

(grammar { token TOP { <a>? $&lt;b&gt;='b' }; token a { a } }).parse​: 'ab'; say $/<b>.keys;
a
(grammar { token TOP { <a> $&lt;b&gt;='b' }; token a { a } }).parse​: 'ab'; say $/<b>.keys;

In the first line $/<b>.keys is not empty contrary to expectations.
Somehow the results of the <a>?
rule leaks into $/<b>.
Note that in the second line, the question mark in <a>? is suppressed
and the bug is not triggered any more.

Maybe the bug will be fixed when the implementation of ? will be
rewritten as per spec (not returning an array).

<cognominal> nom​: (grammar { token TOP { <a>? $<b>='b' }; token a {
a } }).parse​: 'ab'; say $/<b>.keys;
<p6eval> nom 4130f6​: OUTPUT«a␤»
<cognominal> nom​: (grammar { token TOP { <a> $<b>='b' }; token a {
a } }).parse​: 'ab'; say $/<b>.keys;
<p6eval> nom 4130f6​: OUTPUT«␤»
<cognominal> jnthn, this does not make any sense to me that $/<b>.keys
returns anything different than a void Parcel
<cognominal> should I file a bug?
* NamelessTee has quit (Ping timeout​: 244 seconds)
<moritz> nom​: (grammar { token TOP { <a> $<b>='b' }; token { a }
}).parse​: 'ab'; say $/<b>.keys.WHAT;
<p6eval> nom 4130f6​: OUTPUT«Method 'a' not found for invocant of class
'<anon>'␤ in regex TOP at /tmp/fZXy8AXoHU​:1␤ in method parse at
src/gen/CORE.setting​:8019␤ in block <anon> at /tmp/fZXy8AXoHU​:1␤␤»
<moritz> nom​: (grammar { token TOP { <a> $<b>='b' }; token a { a }
}).parse​: 'ab'; say $/<b>.keys.WHAT;
<p6eval> nom 4130f6​: OUTPUT«List()␤»
<moritz> cognominal​: it's returns an empty List, not an empty Parcel.
Is that your problem?
<cognominal> see the first example, it prints "a\n".
<cognominal> I don't care if it is a parcel or a list. Whatever it is
should be empty.
<moritz> agreed
<cognominal> it does not happen when I delete the '?' suffix.
<moritz> though of course the ? quantifier on <a> should not affect $<b>
<cognominal> yes, that's my point.
<moritz> agreed. Bug it is.

--
cognominal stef

From @pmichaud

Now fixed in 0ed00f0.... probably needs spectests to close ticket.

Thanks!

Pm

The RT System itself - Status changed from 'new' to 'open'

From @moritz

tested in S05-capture/named.t.

@moritz - Status changed from 'open' to 'resolved'