Lint/SafeNavigationChain creating non-functional code when [] are involved

[tjschuck]

This is similar to the bug fixed by #4749 (see all the linked issues).

Before:

subscription.customer&.custom_fields[:receipt_recipients].to_s

After running rubocop -a --only Lint/SafeNavigationChain on it:

subscription.customer&.custom_fields&.[:receipt_recipients].to_s

That &.[ is invalid Ruby.

In fact, Rubocop also correctly identifies it as invalid and throws Lint/Syntax: unexpected token tLBRACK2 on it after it made the correction in the first place!

---

Expected behavior

Certainly not generate invalid code!

Interestingly, if you use the same code without the trailing to_s on the chain:

subscription.customer&.custom_fields[:receipt_recipients]

it corrects it to

subscription.customer&.custom_fields&.[](:receipt_recipients)

which is at least correct Ruby, but the &.[](: is pretty gross. I manually fixed my own code using dig instead (custom_fields&.dig(:receipt_recipients)), which reads better to me.

Actual behavior

Here's the full output with --debug that generates the invalid code:

$ cat safe-navigation-with-hash-access.rb
subscription.customer&.custom_fields[:receipt_recipients].to_s

$ rubocop -a --debug --only Lint/SafeNavigationChain safe-navigation-with-hash-access.rb
For /Users/tjschuck/Code/rubocop: configuration from /Users/tjschuck/Code/rubocop/.rubocop.yml
configuration from /Users/tjschuck/.rbenv/versions/3.0.4/lib/ruby/gems/3.0.0/gems/rubocop-performance-1.15.1/config/default.yml
configuration from /Users/tjschuck/.rbenv/versions/3.0.4/lib/ruby/gems/3.0.0/gems/rubocop-performance-1.15.1/config/default.yml
Default configuration from /Users/tjschuck/.rbenv/versions/3.0.4/lib/ruby/gems/3.0.0/gems/rubocop-1.39.0/config/default.yml
configuration from /Users/tjschuck/.rbenv/versions/3.0.4/lib/ruby/gems/3.0.0/gems/rubocop-rspec-2.15.0/config/default.yml
configuration from /Users/tjschuck/.rbenv/versions/3.0.4/lib/ruby/gems/3.0.0/gems/rubocop-rspec-2.15.0/config/default.yml
configuration from /Users/tjschuck/.rbenv/versions/3.0.4/lib/ruby/gems/3.0.0/gems/rubocop-rake-0.6.0/config/default.yml
configuration from /Users/tjschuck/.rbenv/versions/3.0.4/lib/ruby/gems/3.0.0/gems/rubocop-rake-0.6.0/config/default.yml
Inheriting configuration from /Users/tjschuck/Code/rubocop/.rubocop_todo.yml
Use parallel by default.
Skipping parallel inspection: only a single file needs inspection
Inspecting 1 file
Scanning /Users/tjschuck/Code/rubocop/safe-navigation-with-hash-access.rb
Loading cache from /Users/tjschuck/.cache/rubocop_cache/11226f41faec7637153da17318ab9466aeea3fbf/5bd7dd7c49a5710853cb463c9447753a064e7a92/9d1153664702149d21c8f5721ac254facef98fa1
W

Offenses:

safe-navigation-with-hash-access.rb:1:37: W: [Corrected] Lint/SafeNavigationChain: Do not chain ordinary method call after safe navigation operator.
subscription.customer&.custom_fields[:receipt_recipients].to_s
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^

1 file inspected, 1 offense detected, 1 offense corrected
Finished in 0.5164380000060191 seconds

Steps to reproduce the problem

Reproducible with the code snippets above.

RuboCop version

$ rubocop -V
1.39.0 (using Parser 3.1.3.0, rubocop-ast 1.24.0, running on ruby 3.0.4) [x86_64-darwin21]
  - rubocop-performance 1.15.1
  - rubocop-rake 0.6.0
  - rubocop-rspec 2.15.0