Support for i64/u64 in interface types

[ibaryshnikov]

Consider the following code

#[wasm_bindgen]
pub fn render() -> u64 {
    123
}

Compiling it with

WASM_INTERFACE_TYPES=1 wasm-pack build

produces

error: failed to generate a standard wasm bindings custom section
    caused by: failed to map return value for export `render` to standard binding expressions
    caused by: cannot represent 64-bit integer with a standard bindings expression

Expected behavior:
it should correctly generate interface type for the return value

In the proposal the types from u8/s8 to u64/s64 are covered, where u stands for unsigned and s for signed.

wasm-pack 0.8.1
wasm-bindgen 0.2.52
rustc 1.38.0 (625451e37 2019-09-23)

[alexcrichton]

Thanks for the report! This is definitely something that I think we should support better in wasm-bindgen and is sort of "legacy baggage" from the JS target. I've opened up #1841 which is sort of the extension of this issue about how "pure interface types" isn't super well supported today since all the web functionality is mixed in. This would be fixed as part of a split proposed there.

[tiye]

how is this issue in the end of 2021?