Parse error with type annotation in fat-arrow

[fdecampredon]

The parser does not parse type annotation on argument in fat-arrow:

/*@flow*/
var f = (t: string) => t;

***/sampleArrow.js:2:11,11: Unexpected token :

It also does not parse return value type annotation:

/*@flow*/
var f = (t): string => t;

***/sampleArrow.js:2:12,12: Unexpected token :

[sophiebits]

For what it's worth, this works:

var f: (t: string) => string = (t) => t;

[salper]

👍

[ryanisinallofus]

+1

[gabelevi]

I actually just refactored the parser this weekend to make it really easy to add features to arrow functions, like type annotations, type parameters, async, generators, etc. It slows down the parsing at the moment by like 14%, which isn't great, but parsing isn't the majority of our time at the moment so I'm not sure if we mind too much.

[samwgoldman]

This just landed in master (yay!) and will hopefully be fixed in the next release.

[gabelevi]

Also it shouldn't cause a perf regression, thanks to some great advice from @bhosmer :)

[mroch]

0.12 is out, should be fixed!