Rubocop: Lint/ParenthesesAsGroupedExpression incorrectly flags closed expressions

Created on 9 Feb 2016 · 7Comments · Source: rubocop-hq/rubocop

If I have

puts (1 + 2) / 3

This rule fires. It should check that the ) is actually the last character before yelling at me.

Source

ptarjan

All 7 comments

Sorry, what is the (undesired) output of RC here?

alexdowad on 9 Feb 2016

@alexdowad

$ rubocop -D /tmp/a.rb
Inspecting 1 file
W

Offenses:

/tmp/a.rb:1:5: W: Lint/ParenthesesAsGroupedExpression: (...) interpreted as grouped expression.
puts (1 + 2) / 3
    ^

1 file inspected, 1 offense detected

ptarjan on 9 Feb 2016

From the tests for that cop:

  it 'registers an offense for math expression' do
    inspect_source(cop, 'puts (2 + 3) * 4')
    expect(cop.offenses.size).to eq(1)
  end

It appears that this is the desired behavior. Please either use another set of parens to disambiguate, or disable the cop.

This can be closed.

alexdowad on 9 Feb 2016

This is pretty unexpected. We don't use parenthesis for single arg method calls here. What is the protocol, to ask the cop author?

ptarjan on 9 Feb 2016

What is the protocol, to ask the cop author?

I don't know how to answer that question. You said "it should check...", which implied that the cop was buggy. Investigation revealed that it's not buggy; it is functioning as its author intended.

Now, if you disagree with the style choices which the cop author made and want to recommend something else, that can also be discussed. @jonas054, as you are the original author, do you have anything to say?

alexdowad on 10 Feb 2016

For Ruby 1.9 you get this warning from ruby -wc, but in later versions it no longer warns.

For me it makes sense in the general case (puts aside) to warn that func (a + b) / c means func((a + b) / c) and not func(a + b) / c.