How would this handle generic class instantiations?

[dead-claudia]

A major point of conflict between TS/Flow and the ES spec is with generic type instantiation:

let foo = new Foo<T>(1)

That production is parsed by TS and Flow to be a single constructor call, but it's also valid ES, equivalent to the following:

((new Foo) < T) > 1

IMHO, breaking the below code is a non-issue as I very highly doubt anyone is relying on that behavior (and it's easy for browsers to collect usage metrics on, too), but it's still worth mentioning as a potential risk. It also will tremendously complicate any grammar specification for it, requiring probably multiple cover grammars.