`extend_config` no longer working with Rubocop 1.72 plugin

[darronschall]

I have a project using standard with an extend_config to pull in rubocop-rspec. My config is simple:

# .standard.yml
plugins:
  - standard-performance
  - standard-rails

extend_config:
  - .rubocop_rspec.yml

# rubocop_rspec.yml
require:
  - rubocop-rspec

# Easier to read than "is_expected.to"
RSpec/ImplicitExpect:
  EnforcedStyle: should

# Can't always provide meaningful names, especially when testing collections
RSpec/IndexedLet:
  Max: 3

This was working great up until the rubocop-rspec 3.5.0 release, when the gem was changed to a Rubocop 1.72 plugin.

I am no longer able to extend the default configuration of rubocop-rspec. For now I've pinned the gem to 3.4.0, but I'd like to be able to upgrade at some point.

I'm wondering if this is failing for the same reason in the comment at https://github.com/standardrb/standard/issues/540#issuecomment-1474292307, and if extend_config needs some changes, especially as more rubocop extensions migrate towards the plugin approach...

[VikiAnn]

Just noting on each of these issues that I think they're related/possibly duplicative, so that hopefully whenever someone picks up any of them, it's clear how they're tied together:

#715 is potentially duplicative of #701, which mentions possibly being the same issue as #540