This commit adds support to `wasm-bindgen` to emit a WebAssembly module
that contains a WebAssembly Interface Types section. As of today there are no
native consumers of these WebAssembly modules, and the actual binary format
here is basically arbitrary (chosen by the `wasm-webidl-bindings` crate). The
intention is that we'll be following the [WebAssembly Interface
Types proposal][proposal] very closely and update here as necessary.
The main feature added in this PR is that a new experimental environment
variable, `WASM_INTERFACE_TYPES=1`, is recognized by the `wasm-bindgen`
CLI tool. When present the CLI tool will act differently than it does
today:
* The `anyref` feature will be implicitly enabled
* A WebAssembly interface types section will be emitted in the
WebAssembly module
* For now, the WebAssembly module is strictly validated to require zero
JS glue. This means that `wasm-bindgen` is producing a fully
standalone WebAssembly module.
The last point here is one that will change before this functionality is
stabilized in `wasm-bindgen`. For now it reflects the major use case of
this feature which is to produce a standalone WebAssembly module with no
support JS glue, and to do that we need to verify properties like it's
not using JS global names, nonstandard binding expressions, etc. The
error messages here aren't the best but they at least fail compilation
at some point instead of silently producing weird wasm modules.
Eventually it's envisioned that a WebAssembly module will contain an
interface types section but *also* have JS glue so binding expressions
can be used when available but otherwise we'd still generate JS glue for
things like nonstandard expressions and accessing JS global values.
It should be noted that a major feature not implemented in
`wasm-bindgen` yet is the multi-value proposal for WebAssembly. This is
coming soon (as soon as we can) in `walrus` and later for a pass here,
but for now this means that returning multiple values (like a string
which has a pointer/length) is a bit of a hack. To enable this use case
a `wasm-bindgen`-specific-convention which will never be stabilized is
invented here by using binding expression to indicate "this return value
is actually returned through an out-ptr as the first argument list".
This is a gross hack and is guaranteed to be removed. Eventually we will
support multi-value and the wasm module emitted will simply use
multi-value and contain internal polyfills for Rust's ABI which returns
values through out-ptrs.
Overall this should make `wasm-bindgen` usable for playing around with
the WebIDL bindings proposal and helping us get a taste of what it looks
like to have entirely standalone WebAssembly modules running in multiple
environments, no extra fluff necessary!
[proposal]: https://github.com/webassembly/webidl-bindings
Turns out #1704 was buggy and ended up never injecting initialization
because the anyref table was never present! This fixes that issue and
this should now be tested on CI to ensure this doesn't regress and
future changes preserve correctness
This commit updates `wasm-bindgen` to the latest version of `walrus`
which transforms all internal IR representations to a list-based IR
instead of a tree-based IR. This isn't a major change other than
cosmetic for `wasm-bindgen` itself, but involves a lot of changes to the
threads/anyref passes.
This commit also updates our CI configuration to actually run all the
anyref tests on CI. This is done by downloading a nightly build of
node.js which is theorized to continue to be there for awhile until the
full support makes its way into releases.
This commit fixes an issue previously introduced around handling the
anyref table, gracefully handling the case where the source module
doesn't actually use the anyref table at all, meaning that the logic
around initializing it can be entirely skipped.
This functionality got lost in recent refactorings for WebIDL bindings
unfortunately, so this commit touches things up to ensure that the
anyref table initialization in anyref-mode is hooked up correctly, even
when tests are enabled. This invovled moving injection of the start
function to the webidl processing pass and ensuring its intrinsic is
registered in the internal maps of wasm-bindgen.
This commit adds support to `wasm-bindgen` to be a drop-in polyfill for
the WebIDL bindings proposal. Lots of internal refactoring has happened
previously to `wasm-bindgen` to make this possible, so this actually
ends up being a very small PR!
Most of `wasm-bindgen` is geared towards Rust-specific types and
Rust-specific support, but with the advent of WebIDL bindings this is a
standard way for a WebAssembly module to communicate its intended
interface in terms of higher level types. This PR allows `wasm-bindgen`
to be a polyfill for any WebAssembly module that has a valid WebIDL
bindings section, regardless of its producer. A standard WebIDL bindings
section is recognized in any input wasm module and that is slurped up
into wasm-bindgen's own internal data structures to get processed in the
same way that all Rust imports/exports are already processed.
The workflow for `wasm-bindgen` looks the same way that it does in Rust
today. You'd execute `wasm-bindgen path/to/foo.wasm --out-dir .` which
would output a new wasm file and a JS shim with the desired interface,
and the new wasm file would be suitable for loading in MVP
implementations of WebAssembly.
Note that this isn't super thoroughly tested, so there's likely still
some lingering assumptions that `wasm-bindgen` makes (such as
`__wbindgen_malloc` and others) which will need to be patched in the
future, but the intention of this commit is to start us down a road of
becoming a drop-in polyfill for WebIDL bindings, regardless of the
source. Also note that there's not actually any producer (AFAIK) of a
WebIDL bindings custom section, so it'd be that much harder to write
tests to do so!
After this change, any import that only takes and returns ABI-safe numbers (signed
integers less than 64 bits and unrestricted floating point numbers) will be a
direct import, and will not have a little JS shim in the middle.
We don't have a great mechanism for testing the generated bindings' contents --
as opposed to its behavior -- but I manually verified that everything here does
the Right Thing and doesn't have a JS shim:
```rust
\#[wasm_bindgen]
extern "C" {
fn trivial();
fn incoming_i32() -> i32;
fn incoming_f32() -> f32;
fn incoming_f64() -> f64;
fn outgoing_i32(x: i32);
fn outgoing_f32(y: f32);
fn outgoing_f64(z: f64);
fn many(x: i32, y: f32, z: f64) -> i32;
}
```
Furthermore, I verified that when our support for emitting native `anyref` is
enabled, then we do not have a JS shim for the following import, but if it is
disabled, then we do have a JS shim:
```rust
\#[wasm_bindgen]
extern "C" {
fn works_when_anyref_support_is_enabled(v: JsValue) -> JsValue;
}
```
Fixes#1636.
This commit is the second, and hopefully last massive, refactor for
using WebIDL bindings internally in `wasm-bindgen`. This commit actually
fully executes on the task at hand, moving `wasm-bindgen` to internally
using WebIDL bindings throughout its code generation, anyref passes,
etc. This actually fixes a number of issues that have existed in the
anyref pass for some time now!
The main changes here are to basically remove the usage of `Descriptor`
from generating JS bindings. Instead two new types are introduced:
`NonstandardIncoming` and `NonstandardOutgoing` which are bindings lists
used for incoming/outgoing bindings. These mirror the standard
terminology and literally have variants which are the standard values.
All `Descriptor` types are now mapped into lists of incoming/outgoing
bindings and used for process in wasm-bindgen. All JS generation has
been refactored and updated to now process these lists of bindings
instead of the previous `Descriptor`.
In other words this commit takes `js2rust.rs` and `rust2js.rs` and first
splits them in two. Interpretation of `Descriptor` and what to do for
conversions is in the binding selection modules. The actual generation
of JS from the binding selection is now performed by `incoming.rs` and
`outgoing.rs`. To boot this also deduplicates all the code between the
argument handling of `js2rust.rs` and return value handling of
`rust2js.rs`. This means that to implement a new binding you only need
to implement it one place and it's implemented for free in the other!
This commit is not the end of the story though. I would like to add a
mdoe to `wasm-bindgen` that literally emits a WebIDL bindings section.
That's left for a third (and hopefully final) refactoring which is also
intended to optimize generated JS for bindings.
This commit currently loses the optimization where an imported is hooked
up by value directly whenever a shim isn't needed. It's planned that
the next refactoring to emit a webidl binding section that can be added
back in. It shouldn't be too too hard hopefully since all the
scaffolding is in place now.
cc #1524
