This commit adds support for exporting a function defined in Rust that returns a
`Result`, translating the `Ok` variant to the actual return value and the `Err`
variant to an exception that's thrown in JS.
The support for return types and descriptors was rejiggered a bit to be a bit
more abstract and more well suited for this purpose. We no longer distinguish
between functions with a return value and those without a return value.
Additionally a new trait, `ReturnWasmAbi`, is used for converting return values.
This trait is an internal implementation detail, however, and shouldn't surface
itself to users much (if at all).
Closes#841
In addition to closing #495 this'll be useful eventually when instantiating
multiple wasm modules from Rust as you'd now be able to acquire a reference to
the current module in Rust itself.
This commit implements the `JsCast` trait automatically for all imported types
in `#[wasm_bindgen] extern { ... }` blocks. The main change here was to generate
an `instanceof` shim for all imported types in case it's needed.
All imported types now also implement `AsRef<JsValue>` and `AsMut<JsValue>`
This commit starts migrating the `wasm_bindgen` tests to the `wasm_bindgen_test`
framework, starting to assemble the coffin for
`wasm-bindgen-test-project-builder`. Over time all of the tests in
`tests/all/*.rs` should be migrated to `wasm_bindgen_test`, although they may
not all want to go into a monolithic test suite so we can continue to test for
some more subtle situations with `#[wasm_bindgen]`.
In the meantime those, the `tests/all/api.rs` tests can certainly migrate!
