Fix value omission false positive in Style/MethodCallWithArgsParentheses

[gsamokovarov]

Omitting the parentheses in cases like the example below is ambigious, we don't need to enforce their omission in the EnforcedStyle: omit_parentheses

var =
  unless object.action(value:, other:)
    condition || other_condition
  end

If the parentheses in the condition above are omitted, the semantic of
the code is changed:

var =
  unless object.action value:, other:
    condition || other_condition
  end

# is interpreted as:

var =
  unless object.action value:, other: condition || other_condition
    # empty branch
  end

We should allow parentheses in value omissions in conditional nodes.

[bbatsov]

I think all such cases where the parentheses are required should also be listed somewhere in the documentation examples.

[gsamokovarov]

Technically, the parentheses are not required here but omitting them changes the behaviour of the code. There is ambiguity, which should be left to the developer to decide. I found this case by a crash that I fix in #11712.

Documentation about all those cases can be useful so I will write some. Should it be in this PR as another commit?

[bbatsov]

Another commit in this PR would be fine.

Technically, the parentheses are not required here but omitting them changes the behaviour of the code. There is ambiguity, which should be left to the developer to decide. I found this case by a crash that I fix in #11712.

Yeah, yeah - I get this. This particular case should be covered by some generic comment that we don't require/omit parentheses if this is going to change the meaning of the code. Something like a guiding principle for the cop in general.

[gsamokovarov]

I have also cleaned up the examples and added more examples where parentheses are required.

[bbatsov]

I think it'd better to list those cases as bullet points - it will read nicer IMO.

[gsamokovarov]

Should I be exhaustive, though? Those are just a few cases, I can try and present all(most) of the cases here but the list will be quite long.

[bbatsov]

I'm on the fence about this. Given how often we find problems with this cop I'm leaning towards more documentation, so it's clearer how it's supposed to work.

[gsamokovarov]

☝️?

[bbatsov]

The updated docs look great. Thanks!