False positive on Naming/MemoizedInstanceVariableName

[halostatue]

Received Naming/MemoizedInstanceVariableName incorrectly for methods and variables with surrounding underscores.

---

Expected behavior

No Naming/MemoizedInstanceVariableName warning.

Actual behavior

Received message

Naming/MemoizedInstanceVariableName: Memoized variable @__instances__ does not match method name __instances__. Use @__instances__ instead.

Steps to reproduce the problem

Run RuboCop over:

require 'set'

class Foo
  def __instances__
    @__instances__ ||= Set.new
  end
end

RuboCop version

0.63.1 (using Parser 2.5.1.0, running on ruby 2.6.0 x86_64-darwin18)

[pocke]

Thank you for your reporting!

More small code to reproduce:

def _a
  @_a ||= x
end

This cop does not work well if the method name starts with underscore.

related: #6125