Symlinks pointing to excluded directories are not excluded

[ob-stripe]

After upgrading to Rubocop 0.93.0 or a more recent version, symbolic links pointing to directories that are excluded in .rubocop.yml are no longer excluded.

The behavior change was introduced by this PR: #8815

I'm not sure whether you'd consider this a bug, but it's definitely a behavior change that caught us off guard while trying to upgrade Rubocop to a more recent version.

Expected behavior

With Rubocop 0.92.0 or older versions, symbolic links pointing to directories that are excluded in .rubocop.yml were themselves excluded.

E.g. with the following file tree:

$ ls -lR .
total 16
-rw-r--r--   1 ob  staff  109 Mar 23 22:34 .rubocop.yml
-rw-r--r--  1 ob  staff  172 Mar 23 22:29 Gemfile
-rw-r--r--  1 ob  staff  631 Mar 23 22:29 Gemfile.lock
drwxr-xr-x  3 ob  staff   96 Mar 23 22:21 build
drwxr-xr-x  3 ob  staff   96 Mar 23 22:26 foo

./build:
total 0
drwxr-xr-x  3 ob  staff  96 Mar 23 22:24 protoc_out

./build/protoc_out:
total 8
-rw-r--r--  1 ob  staff  764 Mar 23 22:22 ping_pb.rb

./foo:
total 0
lrwxr-xr-x  1 ob  staff  19 Mar 23 22:26 protoc_out -> ../build/protoc_out

and a .rubocop.yml as follows:

AllCops:
  TargetRubyVersion: 2.7
  Exclude:
    - build/protoc_out/**/*

then the contents fo foo/protoc_out were excluded, because the link resolves to build/protoc_out which is itself excluded:

$ bundle exec rubocop -V
0.92.0 (using Parser 3.0.0.0, rubocop-ast 1.4.1, running on ruby 2.7.2 x86_64-darwin19)
$ bundle exec rubocop --list-target-files --debug
For /Users/ob/workspace/ruby/rubocop-test-link: configuration from /Users/ob/workspace/ruby/rubocop-test-link/.rubocop.yml
Default configuration from /Users/ob/workspace/ruby/rubocop-test-link/vendor/bundle/ruby/2.7.0/gems/rubocop-0.92.0/config/default.yml
Gemfile
Finished in 0.08337699994444847 seconds

Actual behavior

With Rubocop 0.93.0 or more recent, symbolic links pointing to directories that are excluded in .rubocop.yml are no longer excluded:

$ bundle exec rubocop -V
0.93.0 (using Parser 3.0.0.0, rubocop-ast 1.4.1, running on ruby 2.7.2 x86_64-darwin19)
$ bundle exec rubocop --list-target-files --debug
For /Users/ob/workspace/ruby/rubocop-test-link: configuration from /Users/ob/workspace/ruby/rubocop-test-link/.rubocop.yml
Default configuration from /Users/ob/workspace/ruby/rubocop-test-link/vendor/bundle/ruby/2.7.0/gems/rubocop-0.93.0/config/default.yml
Gemfile
foo/protoc_out/ping_pb.rb
Finished in 0.08175699971616268 seconds

Steps to reproduce the problem

Set up a file structure as above, and run Rubocop 0.93.0 or more recent.

RuboCop version

$ bundle exec rubocop -V
0.93.0 (using Parser 3.0.0.0, rubocop-ast 1.4.1, running on ruby 2.7.2 x86_64-darwin19)