Misc #16910: BasicObject is resolved in BasicObject

• Status: Closed
• Assignee: -

[fxn (Xavier Noria)]

I categorized this as Misc because I do not really know if this is a bug, or perhaps I miss some special rule in the resolution of relative constants.

Basically, I would expect

class C < BasicObject
  BasicObject
end

or, even simpler,

class BasicObject
  BasicObject
end

to raise NameError.

Reason would be that top-level constants are stored in Object, which is not among the ancestors in any of the two examples above.

Is my reasoning flawed or is it a bug? If flawed, which is the correct reasoning?

[fxn (Xavier Noria)]

Ah, forgot to add that I saw this

BasicObject.constants # => [:BasicObject]

Could it be the case that BasicObject is special-cased somehow? If so, where in the source code?

[Eregon (Benoit Daloze)]

As you found, I think it's just a special case that BasicObject has a constant named "BasicObject".

It's defined here in CRuby:
https://github.com/ruby/ruby/blob/b10c9d201222b144df7d63660d1c731af53c4ae2/class.c#L569
And here in TruffleRuby:
https://github.com/oracle/truffleruby/blob/e2680f10e367eaca2069636109918541b682a7a0/src/main/java/org/truffleruby/core/CoreLibrary.java#L813-L814

I'm not sure why there is this exception, since all other constants basically don't work in a subclass of BasicObject with lexical constant lookup, they need ::Const.

[fxn (Xavier Noria)]

Ahhh, that explains it. That code says this is intentional and definitely not a bug.

Thanks a lot Benoit!

[fxn (Xavier Noria)]

This can be closed (can't do it myself apparently).

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

[Eregon (Benoit Daloze)]

Actually I looked too fast, the correct location is
https://github.com/ruby/ruby/blob/b10c9d201222b144df7d63660d1c731af53c4ae2/class.c#L551-L559

So it's defined as a constant of itself (BasicObject) and not Object because Object is not defined yet it seems.
Those constants could probably be defined later though.

[fxn (Xavier Noria)]

Ah! I read too fast too :). Appreciate the followup!