Rails/IndexWith false positive

[rasaffie]

Expected behavior

Don't auto-correct inject on unsafe cases of Style/EachWithObject + Rails/IndexWith.

Actual behavior

It replaces inject with index_with, but with an undefined variable.

Steps to reproduce the problem

• With code:

def self.make_hash(names)
  names.inject({}) { |result, name| result[name] = Date::MONTHNAMES[result.count + 1]; result }
end

• Run rubocop -a
• It returns:

def self.make_hash(names)
  names.index_with { |_name| Date::MONTHNAMES[result.count + 1]; }
end

where result.count raises exception.

RuboCop version

$ [bundle exec] rubocop -V
0.89.1 (using Parser 2.7.1.4, rubocop-ast 0.3.0, running on ruby 2.7.1 x86_64-linux)

[marcandre]

Indeed, any other reference to the block variable to be eliminated should imply no offense at all.

[marcandre]

Transferring to RuboCop/Rails as Style/EachWithObject's auto-correction is fine:

def self.make_hash(names)
  names.each_with_object({}) { |name, result| result[name] = Date::MONTHNAMES[result.count + 1]; }
end

It's the subsequent transformation with index_by that isn't.