Should extern "C" { ... } be disallowed?

[alexcrichton]

I've noticed in a few locations that we're annotating APIs with:

#[wasm_bindgen]
extern "C" {
     // ...
}

but under the hood there's not actually any semblance of "C"! In fact, it's somewhat more accurate to say something like:

#[wasm_bindgen]
extern "wasm-bindgen" {
    // ...
}

but that's a bit wordy and we shouldn't require that. Should we specifically deny extern "C"?

[ohanar]

The main thing that I don't really like about this is that the default rustfmt configuration wants an explicit abi (and presumably the style guide will have the same suggestion). You can stop rustfmt from auto-inserting "C"s by adding a custom configuration, but we would be asking that for any project that is using custom bindings and rustfmt.

[alexcrichton]

Hm I guess that answers the question for us, alas!