--config FILE argument appears to be ignored when --auto-gen-config is used

[Kache]

Instead of using .rubocop.yml default, I'm using rubocop --config my_path/my_file.yml. In attempting to incorporate --auto-gen-config and todo.yml in order for an incremental fix workflow, I found that rubocop --config my_path/my_file.yml --auto-gen-config operates as if I ran rubocop.

Specifically, this means that all the rules in my config are effectively ignored (and a new .rubocop.yml file is added for me as well).

My workaround is renaming my_path/my_file.yml to .rubocop.yml, and then the --auto-gen-config feature works as expected. (Great to have, by the way!)

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Expected behavior

rubocop --config my_path/my_file.yml --auto-gen-config should operate on my_path/my_file.yml as if it were named .rubocop.yml

Actual behavior

My config file is completely ignored, as if it didn't exist. A new .rubocop.yml is created and modified to inherit .rubocop_todo.yml as well.

Steps to reproduce the problem

Create a custom rubocop configuration at some_path/some_name.yml with a Cop disabled. In a codebase where that Cop would activate, rubocop --config some_path/some_name.yml should not alert.

Then, run rubocop --config some_path/some_name.yml --auto-gen-config, and the cop will have been "reactivated" because the --config argument appears to get ignored.

RuboCop version

0.56.0 (using Parser 2.5.1.0, running on ruby 2.3.7 x86_64-darwin16)