Visibility state of method definitions is not inherited across fibers

[dearblue]

I noticed a different behavior with commit ed00879 than with CRuby.

class A
  #private    # even if this comment section is enabled, the result is the same
  f = Fiber.new { def a; p "BAD!"; end }
  private
  f.resume
end

A.new.a
# (ruby34) => -:7:in '<main>': private method 'a' called for an instance of A (NoMethodError)
# (mruby)  => "BAD!"

I have tried to fix it a bit, but I think I may need to inherit from proc->e.env->flags as well, since I can't see the ci if it crosses over a terminated fiber.
However, I do not know how serious this problem is.
And I don't know if I can fix it right away.

[matz]

I think it's too late for mruby 3.4, but I will consider it. If we don't fix, I will add a note to the limitation.md.

[dearblue]

Interim Report.

I have been able to overcome the issues that I initially reported.
However, the solution to the problem I discovered during the course of my work has not yet been resolved.
It will take some more time.

• patch (WIP): https://gist.github.com/dearblue/17387186c86858d8a0c82bde3faa8ca9#file-mruby-6494a-patch
• (1) new problem: https://gist.github.com/dearblue/17387186c86858d8a0c82bde3faa8ca9#file-6494x1-rb
  This problem was overcome by copying struct mrb_callinfo::vis to struct REnv::flags as described earlier.
• (2) In addition to (1), first issue was overcome by adding the MRB_SEPARATE_MODULE flag to struct mrb_callinfo::vis.
• (3) new problem: https://gist.github.com/dearblue/17387186c86858d8a0c82bde3faa8ca9#file-6494x2-rb
  This problem has not been overcome yet.
  Perhaps we need to make sure to set the MRB_SEPARATE_MODULE flag when calling the #initialize method from the mrb_class_new_class() function.