`no-return-assign` behavior changed with arrow functions

Using the latest eslint (2.0.0-rc.0).

Rule:

{
  "no-return-assign": 2
}

Code:

var data = ''
process.stdin.on('data', buffer => data += buffer.toString())

Produces the error:

  2:26  error  Arrow function should not return assignment  no-return-assign

The rule is functioning correctly, because there’s an implicit return with arrow functions. But I’m wondering if there isn’t a way to keep the rule enabled but accommodate this kind of usage with arrow functions.

The intent of the rule is, primarily, to catch cases where the user intended a comparison but accidentally did an assignment. There’s no chance of that in this example because it’s += not =, yet this is still considered an error because there’s an assignment happening.

Possible ways to accommodate this:

• add an except-arrow-function option, to disable checking on arrow functions
• add a way to specify only checking for assignments with =

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[despairblue]

No idea if that is important for this, but using brackets also suppresses the warning, although it’s still returning the assignment.

// Arrow function should not return assignment
const a = (v) => v.b = 1
// passes
const a = (v) => (v.b = 1)

[nzakas]

At the moment, it doesn’t seem like there’s much support for adding an exception to the rule, so closing (as always, we’ll monitor to see if similar issues pop up in the future.)