This commit improves the codegen for `Closure<T>`, primarily for ZST
where the closure doesn't actually capture anything. Previously
`wasm-bindgen` would unconditionally allocate an `Rc` for a fat pointer,
meaning that it would always hit the allocator even when the `Box<T>`
didn't actually contain an allocation. Now the reference count for the
closure is stored on the JS object rather than in Rust.
Some more advanced tests were added along the way to ensure that
functionality didn't regress, and otherwise the calling convention for
`Closure` changed a good deal but should still be the same user-facing.
The primary change was that the reference count reaching zero may cause
JS to need to run the destructor. It simply returns this information in
`Drop for Closure` and otherwise when calling it now also retains a
function pointer that runs the destructor.
Closes#874
* Regenerate the list of features for the crate given recent
improvements, enabling some more types to be bound.
* Add feature gates for the `css` and `console` namespaces (modules),
gating the APIs by default. Now `web_sys` has zero APIs unless they're
requested.
* Improved the "required feature" documentation for `struct` types to
not list parent classes and mention just the `struct` type instead.
Previously the `link_mem_intrinsics` hack actually had a runtime
overhead by storing a value into a global location, but it turns out we
can actually use a non-inlined function call as part of the *descriptor*
which requires this to be in the final binary, but we'll end up snip'ing
the value at the end.
All in all this should mean that it's not a zero-overhead solution for
linking these intrinsics! The `#[wasm_bindgen]` attribute already has
other problems if the descriptors don't show up, so that's the least of
our issues!
This commit implements support for binding APIs that take
`Uint8ClampedArray` in JS. This is pretty rare but comes up in a
`web-sys` binding or two, and we're now able to bind these APIs instead
of having to omit the bindings.
The `Uint8ClampedArray` type is bound by using the `Clamped` marker
struct in Rust. For example this is declaring a JS API that takes
`Uint8ClampedArray`:
use wasm_bindgen::Clamped;
#[wasm_bindgen]
extern {
fn takes_clamped(a: Clamped<&[u8]>);
}
The `Clamped` type currently only works when wrapping the `&[u8]`, `&mut
[u8]`, and `Vec<u8>` types. Everything else will produce an error at
`wasm-bindgen` time.
Closes#421
All these functions are now provided by upstream compiler-builtins, so
there's no need for us to be binding them automatically. The remaining
`Math_*` functions are also no longer needed on nightly after
https://github.com/rust-lang/rust/pull/54257 but that PR isn't on beta,
so we'll need to leave these here for awhile while beta rides the trains
Bind them all as `JsValue` as that's the "least common ancestor" we can
work with. Fixes up one location in WebIDL where `Option<JsValue>`
arose as we haven't implemented that.
Closes#817
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
Previously `wasm-bindgen` would take its `breaks_if_inlined` shims and
attempt to remove them entirely, replacing calls to `breaks_if_inlined`
to the imported closure factories. This worked great in that it would
remove the `breaks_if_inlined` funtion entirely, removing the "cost" of
the `#[inline(never)]`.
Unfortunately as #864 discovered this is "too clever by half". LLVM's
aggressive optimizations won't inline `breaks_if_inlined`, but it may
still change the ABI! We can't replace calls to `breaks_if_inlined` if
the signature changes, because the function its calling has a fixed signature.
This commit cops out a bit and instead of replacing calls to
`breaks_if_inlined` to the imported closure factories, we instead
rewrite calls to `__wbindgen_describe_closure` to the closure factories.
This means that the `breaks_if_inlined` shims do not get removed. It
also means that the closure factory shims have a third and final
argument (what would be the function pointer of the descriptor function)
which is dead and unused.
This should be a functional solution for now and let us iterate on a
true fix later on (if needed). For now the cost of this
`#[inline(never)]` and the extra unused argument should be quite small.
Closes#864
Did a bunch of grepping for `moz*` and searched for "moz" in rustdoc,
deleting anything that looked mozilla-specific. Now there's nothing left
with the "moz" prefix in rustdoc!
This commit is a large-ish scale reorganization of our examples. The
main goal here is to have a dedicated section of the guide for example,
and all examples will be listed there. Each example's `README` is now
just boilerplate pointing at the guide along with a blurb about how to
run it.
Some examples like `math` and `smorgasboard` have been deleted as they
didn't really serve much purpose, and others like `closures` have been
rewritten with `web-sys` instead of hand-bound bindings.
Overall it's hoped that this puts us in a good and consistent state for
our examples, with all of them being described in the guide, excerpts
are in the guide, and they're all relatively idiomatically using
`web-sys`.
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
