Split Promise<primitive> into raw extern + async wrapper#11
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Methods returning Promise<boolean | string | number> now emit a synchronous Promise-returning extern plus an inherent-impl async fn that awaits and casts the resolved JsValue. The public signature (pub async fn -> Result<T, JsValue>) is unchanged. Why: some wasm-bindgen flavours (notably the workers-rs fork) tightened Promise<T> / JsFuture<T> to require T: JsGeneric, which Rust primitives don't impl, so a direct `pub async fn -> Result<bool, JsValue>` extern fails to compile under those flavours. Routing through js_sys::Promise (no JsGeneric bound) avoids the constraint, and the JsValue::as_* cast happens once in the wrapper instead of at every call site. Custom @throws error types still go through the existing From<JsValue> for CustomError contract via a trailing .into().
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This is the unfortunate aspect of using erasable generics - So rather I think the fix we need here is the conversion of the type to the canonical JS type instead of the Rust primitive on the async generics. |
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closing in favor of #14 |
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Methods returning Promise<boolean | string | number> now emit a synchronous Promise-returning extern plus an inherent-impl async fn that awaits and casts the resolved JsValue. The public signature (pub async fn -> Result<T, JsValue>) is unchanged.
Why: some wasm-bindgen flavours (notably the workers-rs fork) tightened Promise / JsFuture to require T: JsGeneric, which Rust primitives don't impl, so a direct
pub async fn -> Result<bool, JsValue>extern fails to compile under those flavours. Routing through js_sys::Promise (no JsGeneric bound) avoids the constraint, and the JsValue::as_* cast happens once in the wrapper instead of at every call site. Custom @throws error types still go through the existingFrom for CustomError contract via a trailing .into().