This commit adds a new attribute to `#[wasm_bindgen]`: `start`. The
`start` attribute can be used to indicate that a function should be
executed when the module is loaded, configuring the `start` function of
the wasm executable. While this doesn't necessarily literally configure
the `start` section, it does its best!
Only one crate in a crate graph may indicate `#[wasm_bindgen(start)]`,
so it's not recommended to be used in libraries but only end-user
applications. Currently this still must be used with the `crate-type =
["cdylib"]` annotation in `Cargo.toml`.
The implementation here is somewhat tricky because of the circular
dependency between our generated JS and the wasm file that we emit. This
circular dependency makes running initialization routines (like the
`start` shim) particularly fraught with complications because one may
need to run before the other but bundlers may not necessarily respect
it. Workarounds have been implemented for various emission strategies,
for example calling the start function directly after exports are wired
up with `--no-modules` and otherwise working around what appears to be
a Webpack bug with initializers running in a different order than we'd
like. In any case, this in theory doesn't show up to the end user!
Closes#74
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 removes the need for an injected `ConstructorToken` type and
also cleans up the story we have for generating constructors a bit.
After this commit a `constructor()` is omitted entirely if we're in
non-debug mode and there's no actual listed constructor. Additionally we
don't deal with splat arguments and rerouting constructors, Nick was
kind enough to enlighten me about `Object.create` which is creating an
instance without running the constructor!
Instances of an exported type are now created through one of two
methods:
* If `#[wasm_bindgen(constructor)]` is present, then a `constructor` is
generated with the appropriate signature. If a constructor is not
present and we're in debug mode, a throwing constructor is generated.
If we're in release mode and there's no constructor, no constructor is
generated.
* Otherwise if a binding returns an instance of a type (or otherwise
needs to manfuacture an instance, then it will cause an internal
`__wrap` function to be generated. This function will use
`Object.create` to create an instance without running the constructor.
This should ideally clean up our generated JS for classes quite a bit,
making it much more lean-and-mean!
If the setter doesn't start with `set_*` then we currently panic, but
panicking is bad! Instead let's thread through structured errors to make
sure they make their way to the top
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
This is intended to address #834 where we don't actually want methods scoped
like this! Instead we'll provide one unique accessor for the `window` object
itself.
This commit adds further support for the `Global` attribute to not only emit
structural accessors but also emit functions that don't take `&self`. All
methods on a `[Global]` interface will not require `&self` and will call
functions and/or access properties on the global scope.
This should enable things like:
Window::location() // returns `Location`
Window::fetch(...) // invokes the `fetch` function
Closes#659
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
This commit implements the `extends` attribute for `#[wasm_bindgen]` to
statically draw the inheritance hierarchy in the generated bindings, generating
appropriate `AsRef`, `AsMut`, and `From` implementations.
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>`
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.
* Make ConvertToAst trait fallible
It's got some panics, and we'll be switching those to errors!
* First example of a diagnostic-driven error
Add a diagnostic-driven error `#[wasm_bindgen]` being attached to public
functions, and add some macros to boot to make it easier to generate errors!
* Result-ify `src/parser.rs`
This commit converts all of `src/parser.rs` away from panics to using
`Diagnostic` instead. Along the way this adds a test case per changed `panic!`,
ensuring that we don't regress in these areas!
This commit starts to add infrastructure for targeted diagnostics in the
`#[wasm_bindgen]` attribute, intended eventually at providing much better errors
as they'll be pointing to exactly the code in question rather than always to a
`#[wasm_bindgen]` attribute.
The general changes are are:
* A new `Diagnostic` error type is added to the backend. A `Diagnostic` is
created with a textual error or with a span, and it can also be created from a
list of diagnostics. A `Diagnostic` implements `ToTokens` which emits a bunch
of invocations of `compile_error!` that will cause rustc to later generate
errors.
* Fallible implementations of `ToTokens` have switched to using a new trait,
`TryToTokens`, which returns a `Result` to use `?` with.
* The `MacroParse` trait has changed to returning a `Result` to propagate errors
upwards.
* A new `ui-tests` crate was added which uses `compiletest_rs` to add UI tests.
These UI tests will verify that our output improves over time and does not
regress. This test suite is added to CI as a new builder as well.
* No `Diagnostic` instances are created just yet, everything continues to panic
and return `Ok`, with the one exception of the top-level invocations of
`syn::parse` which now create a `Diagnostic` and pass it along.
This commit does not immediately improve diagnostics but the intention is that
it is laying the groundwork for improving diagnostics over time. It should
ideally be much easier to contribute improved diagnostics after this commit!
cc #601
* Fix importing the same identifier from two modules
This needed a fix in two locations:
* First the generated descriptor function needed its hash to include the module
that the import came from in order to generate unique descriptor functions.
* Second the generation of the JS shim needed to handle duplicate identifiers in
a more uniform fashion, ensuring that imported names didn't clash.
* Fix importing the same name in two modules
Previously two descriptor functions with duplicate symbols were emitted, and now
only one function is emitted by using a global table to keep track of state
across macro invocations.
