gh-125198: Simplifying rules for slash_no_default, slash_with_default rules.

[Ketchp]

Implementation of changes to slash_no_default, slash_with_default rules.

Joined alternatives together by using group and action for positive lookahead.

• Issue: Grammar for slash_no_default and slash_with_default can be simplified. #125198

[ghost]

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[pablogsal]

Unfortunately I don't think this is a good idea, specially with that void cast over there. There is no measurable performance benefit and makes the grammar more unreadable so I'm -1

@lysnikolaou WDYT?

[efimov-mikhail]

I agree with @pablogsal. Such change makes very little sense, since there is no improvements at all. Providing less lines of grammar at any cost is not a goal.

W/o hacks like (void *) conversions it may be appropriate, but with them it is not, IMO.

[pablogsal]

Closing as per above. Thanks a lot for the suggestion @Ketchp and sorry we could not go with it this time