An error occurred while Style/TrailingCommaInArguments cop was inspecting...

[Domon]

Expected behavior

RuboCop reports offenses (if any) without any unknown error.

Actual behavior

RuboCop reports no offenses but ends with an unknown error.

Steps to reproduce the problem

$ cat test.rb
foo.bar(
  x: 1,
)&.fetch(:y)

$ bundle exec rubocop test.rb
Inspecting 1 file
An error occurred while Style/TrailingCommaInArguments cop was inspecting /Users/domon/src/elements-revenue-period-finalizer/test.rb:1:0.
To see the complete backtrace run rubocop -d.
.

1 file inspected, no offenses detected

1 error occurred:
An error occurred while Style/TrailingCommaInArguments cop was inspecting /Users/domon/src/elements-revenue-period-finalizer/test.rb:1:0.
Errors are usually caused by RuboCop bugs.
Please, report your problems to RuboCop's issue tracker.
https://github.com/rubocop-hq/rubocop/issues

Mention the following information in the issue report:
0.64.0 (using Parser 2.6.0.0, running on ruby 2.6.0 x86_64-darwin18)

RuboCop version

$ bundle exec rubocop -V
0.64.0 (using Parser 2.6.0.0, running on ruby 2.6.0 x86_64-darwin18)

[Drenmi]

Hi, @Domon!

What is your configured TargetRubyVersion? To be able to parse the lonely operator (&.), it needs to be 2.3 or higher. When using TargetRubyVersion: 2.6, this doesn't generate an error on current master, but it does when using TargetRubyVersion: 2.2.

[Domon]

Hi @Drenmi 👋

I can reproduce the error with TargetRubyVersion: 2.6 and RuboCop 0.64.0.

The following is my minimal .rubocop.yml to reproduce the error.

AllCops:
  TargetRubyVersion: 2.6
Style/TrailingCommaInArguments:
  EnforcedStyleForMultiline: comma
Style/FrozenStringLiteralComment:
  Enabled: false

[Drenmi]

Thanks! I was able to reproduce the issue on master with the settings you provided. 🙇