When you refine String with to_regexp, then it breaks Regexp.try_convert even when the refinement is not used
I’ve run into a very strange bug with refinements. Let me show you:
module Ref refine String do def to_regexp end end end Regexp.try_convert('foo') # or Regexp.union('foo', 'bar')
bug.rb:8:in `try_convert': undefined method `to_regexp' for "foo":String (NoMethodError) from test.rb:8:in `<main>'
Note that the refinement is not used (using), only declared, and yet it has affected behaviour of the refined class! This problem occurs only when the method is named
to_string. It seems that there’s some serious scoping issue with refinements.
I’ve reproduced this issue on MRI 2.2.2p95, 2.1.5p273, and 2.0.0p598.