When, for example, a function is moved between from one place to another we recrawl and end up double counting any references it holds to the upper scope. This protects against that. (The same thing is done for constant violations in the `reassign` method)
The flag to control whether we should warn didn't take into account
nested calls or scope chains. An easier approach is to have a
counter. That way we know for sure if we're somewhere deep inside a
crawl call or not.
I previously tried an approach to scope bindings from var to scope but
it didn't catch all cases. This is evident in this bug:
https://phabricator.babeljs.io/T2892
Where even after transforming a const to a var we still get an error
that it's read-only.
This approach will go through and delete every existing let and const
binding and creates a new one with the kind "var"
As an artificat of compiling methods to named function expressions the
function name is being considered a "local" binding in the function
body. This means that we will throw errors anytime someone would want to
create a new local binding with the same name.
This is solved by assigning a symbol to function Identifiers that
indicates that they should not be considered local bindings.
Removed `@flow` annotation from files that don't actually pass Flow check at the moment. These will be added back file by file once the files are properly converted to use Flow.
Closes#3064
I'm extremely stupid and didn't commit as I go. To anyone reading this
I'm extremely sorry. A lot of these changes are very broad and I plan on
releasing Babel 6.0.0 today live on stage at Ember Camp London so I'm
afraid I couldn't wait. If you're ever in London I'll buy you a beer
(or assorted beverage!) to make up for it, also I'll kiss your feet and
give you a back massage, maybe.
