This commit implements a system that will assert that all
`#[wasm_bindgen]` attributes are actually used during compilation. This
should help ensure that we don't sneak in stray attributes that don't
actually end up having any meaning, and hopefully make it a bit easier
to learn `#[wasm_bindgen]`!
This commit switches all imports of JS methods to `structural` by
default. Proposed in [RFC 5] this should increase the performance of
bindings today while also providing future-proofing for possible
confusion with the recent addition of the `Deref` trait for all imported
types by default as well.
A new attribute, `host_binding`, is introduced in this PR as well to
recover the old behavior of binding directly to an imported function
which will one day be the precise function on the prototype. Eventually
`web-sys` will switcsh over entirely to being driven via `host_binding`
methods, but for now it's been measured to be not quite as fast so we're
not making that switch yet.
Note that `host_binding` differs from the proposed name of `final` due
to the controversy, and its hoped that `host_binding` is a good
middle-ground!
[RFC 5]: https://rustwasm.github.io/rfcs/005-structural-and-deref.html
This commit fixes annotations that include both the `constructor` and `catch`
attributes on imported types, ensuring that we infer the right type being
returned after extracting the first type parameter of the `Result`.
Closes#735
First added in #161 this never ended up panning out, so let's remove the
experimental suport which isn't actually used by anything today and hold off on
any other changes until an RFC happens.
