Using $/ is not exactly the same as using any other variable in grammar actions

Question

In theory, and according to the documentation, you can use any argument for methods in grammar actions.

grammar G {
    token TOP { \w+ }
}

class Action-Arg {
    method TOP ($match) { $match.make: ~$match }
}

class Action {
    method TOP ($/) { make ~$/ }
}

class Action-Fails {
    method TOP ($match) { make ~$match }
}

say G.parse( "zipi", actions => Action-Arg );
say G.parse( "zape", actions => Action );
say G.parse( "pantuflo", actions => Action-Fails );

However, the two first versions work as expected. But the third one (which would be a direct translation of the second), fails with

Cannot bind attributes in a Nil type object
  in method TOP at match-and-match.p6 line 19
  in regex TOP at match-and-match.p6 line 7
  in block <unit> at match-and-match.p6 line 24

There's probably some special syntax going on (in the sense of make being actually $/.make, probably), but I'd just like to clarify if this is according to spec or is a bug.

Answer 1

That is because the make subroutine is one of those rare cases in Rakudo where it actually tries to access the $/ variable from the scope it is called from. Which is also how it is documented:

The sub form operates on the current $/

(from the documentation)