Style/FetchEnvVar autocorrect not very readable in boolean-or chains

[merrilymeredith]

The Style/FetchEnvVar cop is autocorrecting to code that doesn't seem like a style improvement when given code that accepts a few possible ENV variable names or has a chain of alternatives. Note that since ENV values are strings, || does not risk discarding a 0 in the environment as it's a truthy "0" right now.

-      ENV["LOG_NAME"] || Core.app_name || File.basename($PROGRAM_NAME)
+      ENV.fetch("LOG_NAME") { Core.app_name } || File.basename($PROGRAM_NAME)

-      ENV["BUILD_METADATA"] || ENV["APPBASE_BUILD_METADATA"] || File.read("/BUILD_METADATA")
+      ENV.fetch("BUILD_METADATA") { ENV.fetch("APPBASE_BUILD_METADATA") { File.read("/BUILD_METADATA") } }

This satisfies the cop and might be a better autocorrect when there's more than a single alternative, but it's still a bit odd:

ENV.fetch("FOO", nil) || ENV.fetch("BAR", nil) || baz

and short sets of options seem like too little to switch to an array-oriented way of doing this:

ENV.values_at("BUILD_METADATA", "APPBASE_BUILD_METADATA").compact.first || File.read("/BUILD_METADATA")

I'd ask someone to prefer simplicity over cleverness if I saw the above.

One could definitely get out of hand with with a boolean chain but I'm sure they'd cross other cops in doing so, while the longest examples I'm dealing with here are 3 terms. Four is the point where I'd personally switch to a different style or refactor.

I think this cop could be relaxed when it finds ENV[...] || ... on the LHS of another || ...?

RuboCop version

1.30.1 (using Parser 3.1.2.0, rubocop-ast 1.18.0, running on ruby 3.1.2 x86_64-linux)
  - rubocop-rspec 2.11.1

[jonas054]

@j-miyake Do you have any comments on this?

[j-miyake]

Indeed. The autocorrect of this cop may decrease readability like the case reported by this issue. Initially, I took this as a trade-off, but considering some improvements or comments (like #10652, #10585 (comment)) made until today, ENV[] in LHS of || operator probably should be allowed because the || is put by the developer who knows the LHS may be nil. I would like to hear others' thoughts.
(cc @koic @bbatsov)

[j-miyake]

The code would be like this if we relax the cop.