Style/MutableConstant false positive for heredoc with frozen_string_literal

[denys-husiev-perfectial]

Rubocop asks to freeze constant string(written with multiline heredoc style) when # frozen_string_literal: true

---

Expected behavior

No error occures

Actual behavior

[Correctable] Style/MutableConstant: Freeze mutable objects assigned to constants

Steps to reproduce the problem

# frozen_string_literal: true

class MyClass

  MY_CONSTANT = <<~LUA # raises Style/MutableConstant offence
    lorem ipsum
    lorem ipsum
  LUA

end

RuboCop version

rubocop -V
1.20.0 (using Parser 3.0.2.0, rubocop-ast 1.11.0, running on ruby 3.0.2 x86_64-darwin20)
  - rubocop-faker 1.1.0
  - rubocop-performance 1.11.5
  - rubocop-rails 2.11.3
  - rubocop-rspec 2.4.0

.rubocop.yml
  TargetRubyVersion: 3.0

[Zhao-Andy]

Hello, I was working on a related example and I was wondering, this should be frozen after all right? I ran the Rubocop auto correcter and it corrected to this:

# frozen_string_literal: true

class MyClass

  MY_CONSTANT = <<~LUA.freeze # calling .freeze does not raise Style/MutableConstant offense
    lorem ipsum
    lorem ipsum
  LUA

end

Feel free to correct me if I'm wrong as I don't work with frozen HEREDOCs too much. :)

RuboCop version

rubocop -V
1.22.0 (using Parser 3.0.2.0, rubocop-ast 1.12.0, running on ruby 3.0.2 x86_64-linux)
  - rubocop-performance 1.11.5
  - rubocop-rails 2.12.2
  - rubocop-rspec 2.5.0
  
.rubocop.yml
  TargetRubyVersion: 3.0

[dvandersluis]

Your heredoc would be frozen, and that .freeze triggers an Style/RedundantFreeze offense:

test.rb:5:17: C: [Correctable] Style/RedundantFreeze: Do not freeze immutable objects, as freezing them has no effect.
  MY_CONSTANT = <<~LUA.freeze # calling .freeze does not raise Style/MutableConstant offense
                ^^^^^^^^^^^^^

What was the original code that was autocorrected to your example?

[Zhao-Andy]

Original code was:

class MyClass

  MY_CONSTANT = <<~LUA
    lorem ipsum
    lorem ipsum
  LUA

end

Actually figured it out -- I think I had some cached version of Rubocop that was running (1.20.0).

Sorry for the noise, and thanks for the explanation!

[dvandersluis]

Glad you figured it out @Zhao-Andy!