New Lint/AmbiguousOperatorPrecedence: problems with shift operator

[andrew-aladev]

Please create file sample.rb:

a = 1 + 2 * (3 << 4)

rubocop --only="Lint/AmbiguousOperatorPrecedence" sample.rb

---

Expected behavior

Everything is fine.

Actual behavior

W: [Correctable] Lint/AmbiguousOperatorPrecedence: Wrap expressions with varying precedence with parentheses to avoid ambiguity.
a = 1 + 2 * (3 << 4)
        ^^^^^^^^^^^^

RuboCop version

$ [bundle exec] rubocop -V
1.21.0 (using Parser 3.0.2.0, rubocop-ast 1.11.0, running on ruby 3.0.2 x86_64-linux)

See also #10047.

[dvandersluis]

I'm not sure what the bug is here? The offense is not because of the << operator, but because of the + operator. Since * has higher precedence than +, the parentheses disambiguate the right side of the + operation.

The idea is that the parentheses will make it obvious that this expression can be expressed as:

b = 2 * (3 << 4)
a = 1 + b

In other words, if you didn't know the order of precedence in ruby, it's impossible to know if 1 + 2 * (3 << 4) is (1 + 2) * (3 << 4) or 1 + (2 * (3 << 4)), which is what this cop is addressing.

[andrew-aladev]

Ok, thank you. I am going to disable this cop.

So this is not a bug.