Reported in #1191 the fix requires us to get a bit creative I think. The
general gist is that a block like this:
#[wasm_bindgen]
impl Foo {
pub fn foo() {}
}
was previously expanded all in one go. Now, however, it's expanded into:
impl Foo {
#[__wasm_bindgen_class_marker(Foo = "Foo")]
pub fn foo() {}
}
// goop generated by orginal #[wasm_bindgen]
This method of expansion takes advantage of rustc's recursive expansion
feature. It also allows us to expand `impl` blocks and allow inner items
to not be fully expanded yet, such as still having `#[cfg]` attributes
(like in the original bug report).
We use theinternal `__wasm_bindgen_class_marker` to indicate that we're
parsing an `ImplItemMethod` unconditionally, and then generation
proceeds as usual. The only final catch is that when we're expanding in
an `impl` block we have to generate tokens for the `Program`
(wasm-bindgen injected goop like the custom section) inside the body
of the function itself instead of next to it. Otherwise we'd get syntax
errors inside of impl blocks!
Closes#1191
The bindings generation for a class would accidentally omit the `__wrap`
function if it was only discovered very late in the process that
`__wrap` was needed, after we'd already passed the point where we needed
to have decided that.
This commit moves struct field generation of bindings much earlier in
the binding generation process which should ensure everything is all
hooked up by the time we generate the classes themselves.
Closes#949
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!
