Style/MethodCallWithArgsParentheses blows up when using --auto-gen-config

[sambostock]

Style/MethodCallWithArgsParentheses blows up when trying to use --auto-gen-config on a project which violates it.

---

Expected behavior

--auto-gen-config should generate the config without blowing up

Actual behavior

It blows up with undefined method 'to_sym' for nil:NilClass when trying to generate the config:

$ bundle exec rubocop --auto-gen-config
Phase 1 of 2: run Layout/LineLength cop
Inspecting 2 files
..

2 files inspected, no offenses detected
Created .rubocop_todo.yml.
Phase 2 of 2: run all cops
Inspecting 2 files
CC

2 files inspected, 8 offenses detected
undefined method `to_sym' for nil:NilClass
~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cop/mixin/configurable_enforced_style.rb:65:in `style'
~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cop/style/method_call_with_args_parentheses.rb:153:in `initialize'
~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/disabled_config_formatter.rb:124:in `new'
~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/disabled_config_formatter.rb:124:in `output_cop_comments'
...

Rest of stack trace

~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/disabled_config_formatter.rb:99:in `output_cop' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/disabled_config_formatter.rb:86:in `block in output_offenses' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/disabled_config_formatter.rb:85:in `each' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/disabled_config_formatter.rb:85:in `output_offenses' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/disabled_config_formatter.rb:52:in `finished' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/formatter_set.rb:33:in `block (3 levels) in <class:FormatterSet>' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/formatter_set.rb:33:in `each' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/formatter/formatter_set.rb:33:in `block (2 levels) in <class:FormatterSet>' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/runner.rb:81:in `inspect_files' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/runner.rb:39:in `run' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/command/execute_runner.rb:21:in `execute_runner' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/command/execute_runner.rb:13:in `run' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/command.rb:10:in `run' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/environment.rb:17:in `run' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/command/auto_genenerate_config.rb:100:in `execute_runner' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/command/auto_genenerate_config.rb:78:in `run_all_cops' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/command/auto_genenerate_config.rb:22:in `run' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/command.rb:10:in `run' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli/environment.rb:17:in `run' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli.rb:65:in `run_command' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli.rb:70:in `execute_runners' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/lib/rubocop/cli.rb:41:in `run' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/exe/rubocop:13:in `block in <top (required)>' /opt/rubies/2.6.3/lib/ruby/2.6.0/benchmark.rb:308:in `realtime' ~/.gem/ruby/2.6.3/gems/rubocop-0.79.0/exe/rubocop:12:in `<top (required)>' ~/.gem/ruby/2.6.3/bin/rubocop:23:in `load' ~/.gem/ruby/2.6.3/bin/rubocop:23:in `<top (required)>' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/cli/exec.rb:74:in `load' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/cli/exec.rb:74:in `kernel_load' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/cli/exec.rb:28:in `run' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/cli.rb:463:in `exec' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/vendor/thor/lib/thor/invocation.rb:126:in `invoke_command' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/vendor/thor/lib/thor.rb:387:in `dispatch' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/cli.rb:27:in `dispatch' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/vendor/thor/lib/thor/base.rb:466:in `start' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/cli.rb:18:in `start' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/exe/bundle:30:in `block in <top (required)>' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/lib/bundler/friendly_errors.rb:124:in `with_friendly_errors' ~/.gem/ruby/2.6.3/gems/bundler-1.17.3/exe/bundle:22:in `<top (required)>' ~/.gem/ruby/2.6.3/bin/bundle:23:in `load' ~/.gem/ruby/2.6.3/bin/bundle:23:in `<main>'

Steps to reproduce the problem

1. Create a new directory

2. Create the following Gemfile

# Gemfile.rb
source 'https://rubygems.org'
gem 'rubocop'

The calls to source and gem violate the Style/MethodCallWithArgsParentheses rule.

3. Create the following Rubocop config

# .rubocop.yml
Style/MethodCallWithArgsParentheses:
  Enabled: true

4. bundle install

5. bundle exec rubocop --auto-gen-config 💥

RuboCop version

$ bundle exec rubocop -V
0.79.0 (using Parser 2.7.0.2, running on ruby 2.6.3 x86_64-darwin19)

[buehmann]

This sounds like it could be related to some changes I did recently on this cop. I can take a look tomorrow.