Parsing error with polymorphic anonymous functions

[bodhi]

Sorry if this is the wrong repo to post this on!

With this file:

/* @flow */
function a<U>(b: U): U {
    return b
}

const a2 = <U>(b: U): U => {
    return b
}

I get this error running ESLint with Babel-eslint:

a.js
  7:5  error  Parsing error: Unexpected token

Which is the return in the body of a2. With an implicit return, I get a different error:

const a3 = <U>(b: U): U => b

=>  xx:15  error  Parsing error: Unterminated JSX contents

Flow has no problems with any of the declarations.

[bodhi]

Oops, forgot to say I saw this with v5.0.0 and v6.0.0-beta.1.

[hzoo]

If it's valid in flow, then it will need to be supported in babylon (babel's parser)

[danez]

This is fixed in babylon 6.8.2.