wasm-bindgen/wasm-bindgen 0.2.121

on GitHub

Added

• Added the slice_to_array attribute for imported JS functions,
  which makes a &[T] (or Option<&[T]>) argument arrive on the JS
  side as a plain Array rather than a typed array — without
  changing the Rust-side &[T] signature. Useful when binding JS
  APIs that take T[] rather than TypedArray<T>. For primitive
  element kinds the wire is the same zero-copy borrow used by plain
  &[T], with the JS-side shim wrapping the view in Array.from(...)
  to materialise the Array — no extra allocation. For String,
  JsValue, and JS-imported element types the Rust side builds a
  fresh [u32] index buffer that JS reads and frees, with per-element
  &T -> JsValue (refcount bump for handle-shaped types). No T: Clone bound is required. The attribute can be set per-fn
  (#[wasm_bindgen(slice_to_array)] fn ...) or per-block on an
  extern "C" { ... } declaration to apply to every imported function
  in that block. &[ExportedRustStruct] remains unsupported (use
  owned Vec<T> for that). Has no effect on exported functions;
  default &[T] (typed-array view / memory borrow) and owned
  Vec<T> semantics are unchanged for callers that didn't opt in.
  See the
  slice_to_array guide page.
  #5145

• Added js_sys::AggregateError bindings (constructor, errors getter, and
  new_with_message / new_with_options overloads). AggregateError represents
  multiple unrelated errors wrapped in a single error, e.g. as thrown by
  Promise.any when all input promises reject, along with js_sys::ErrorOptions,
  accepted by built-in error constructors. ErrorOptions::new(cause)
  constructs an instance pre-populated with cause, and get_cause /
  set_cause provide typed access to the property. All standard error
  constructors that previously took only a message (EvalError,
  RangeError, ReferenceError, SyntaxError, TypeError, URIError,
  WebAssembly.CompileError, WebAssembly.LinkError,
  WebAssembly.RuntimeError) now expose a new_with_options(message, &ErrorOptions) overload, and Error gains
  new_with_error_options(message, &ErrorOptions) alongside the existing
  untyped new_with_options. AggregateError::new_with_options also takes
  &ErrorOptions.
  #5139

• Added inheritance for Rust-exported types: an exported struct may
  declare #[wasm_bindgen(extends = Parent)] to inherit from another
  exported #[wasm_bindgen] struct. The macro injects a hidden
  parent: wasm_bindgen::Parent<Parent> field (a refcounted cell around
  the parent value) and emits class Child extends Parent in the
  generated JS / .d.ts. The child gets an AsRef<Parent<Parent>> impl
  for the direct parent, and threads per-class pointer slots through
  the wasm ABI so that instanceof Parent is true and parent methods
  dispatch soundly via the JS prototype chain. From inside child
  methods, parent data is reached via self.parent.borrow() /
  self.parent.borrow_mut(). See the new
  extends guide page.
  #5120

• Added js_sys::FinalizationRegistry bindings (constructor, register,
  register_with_token, and unregister). The cleanup callback parameter
  is typed as &Function<fn(JsValue) -> Undefined>, so closures created via
  Closure::new can be passed using Function::from_closure (for owned
  closures retained by JS) or Function::closure_ref (for borrowed scoped
  closures). Pairs with the existing js_sys::WeakRef bindings.
  #5140

• Added support for well-known symbols in js_name, getter, and
  setter via the explicit bracket-string form
  "[Symbol.<name>]". This works for imported and exported methods,
  fields, getters, and setters. For example,
  #[wasm_bindgen(js_name = "[Symbol.iterator]")] on an exported method
  generates [Symbol.iterator]() { ... } on the generated JS class, and
  the same syntax works for getter / setter and for imported items.
  #4230

• Added level 2 bindings for ViewTransition to web-sys.
  #5138

• Add support for dynamic unions: a #[wasm_bindgen] enum that mixes string-literal
  variants with single-field tuple variants is now exported as an untagged TypeScript
  union and dispatched dynamically at the JS↔Rust boundary. The new enum-level
  #[wasm_bindgen(fallback)] attribute makes the last tuple variant an
  unconditional catch-all, supporting unions whose trailing variant has no
  runtime check (e.g., interface-only imports). String enums and dynamic
  unions now emit export type (was bare type) so the alias is a named
  export, and both honour the private flag to suppress the keyword.
  #4734
  #2153
  #2088

Fixed

• From<Promise<T>> for JsFuture<T> and IntoFuture for Promise<T> now
  accept any T: FromWasmAbi (rather than T: JsGeneric), letting
  imported async fns return dynamic-union enums.

• TryFromJsValue for C-style enums no longer accepts non-numeric values
  via JS unary + coercion. Previously calling dyn_into::<MyEnum>() on
  a string would silently coerce it via +"foo" (yielding NaN, then
  NaN as u32 = 0) and could match a discriminant by accident; the
  conversion now returns None for any value that is not a JS number.
  #4734

• Fix compilation failure with no_std + release
  #5134

• Raw identifiers (r#name) on enums, enum variants, extern types, statics,
  and impl blocks no longer leak the r# prefix into generated JS / TS
  output and shim names. The Rust-side identifier and the JS-side name are
  now tracked separately for enum variants, and all known identifier
  fallback paths apply Ident::unraw() so e.g.
  pub enum r#Enum { r#A } generates Enum.A instead of producing
  syntactically invalid JS.
  #4323

• Using the -C panic=unwind option when building for the bundler target
  would produce invalid JS.
  #5142

Changed

• js_sys::DataView now implements the js_sys::TypedArray trait. A
  FIXME notes that the trait should be renamed to ArrayBufferView in
  the next major release to better reflect the WebIDL spec name covering
  both DataView and the typed-array types.
  #5135