[perl #67128] [BUG] Null PMC access when matching against grammar G in module M in a rule in Rakudo

[Carl Mäsak]

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<masak> rakudo: module M; grammar G {}; say "foo" ~~ /<M::G>/
<p6eval> rakudo 5351a3: OUTPUT«Null PMC access in set_attr_str() [...]
<masak> I know that's not the way to match against a grammar, but --
look, a Null PMC access!
* masak submits a rakuodbug

[Larry Wall via RT]

Don't need this, using the Top or other rule name is sufficient.