Wasm-bindgen: [...] `/path/to/project/root/package.json` can currently [..] have [...] no other fields

[pablosichert]

Hey there!

I have a project directory, where both cargo and npm reside. The package.json has, among others, a scripts section to centralize custom commands related to the project.

When I add

#[wasm_bindgen(module = "/src/foo.ts")]
[...]

to a Rust file, I get the following error when compiling (in this case by invoking wasm-pack, but it should be unrelated):

error: NPM manifest found at `/path/to/project/root/package.json` can currently only have one key, `dependencies`, and no other fields
Error: Running the wasm-bindgen CLI
Caused by: failed to execute `wasm-bindgen`: exited with exit code: 1

Can you help me understand why this limitation exists? Why is e.g. ignoring the other keys not an option?

[adam-cyclones]

I am also having the same issue (I am also in a ts project)

I changed my import to point to some JS incase it was that.

#[wasm_bindgen(module = "lib-jess/src/bindings/ts/helpers/import.js")]
extern "C" {
    fn import_jess_sync(path: &str) -> Result<String, JsValue>;
}

[pratyushj]

I was using JS and had the same error. Had to move all the JS code to a separate folder and it worked :grimacing:

[adam-cyclones]

Interesting il try that. I think the function I wanted to export was in the same folder as some ts sources. This looks like an edge case and some unexpected behaviour, certainly unhelpful error either way.

[alexcrichton]

Thanks for the report! This was initially done to be as conservative as possible, but I think that this has tripped up enough users that it's fine to ignore all non-dependencies keys and only use the ones that are relevant. In that sense I'd be happy to have a PR to change this!

[adam-cyclones]

@alexcrichton its this code at crates/cli-support/src/js/mod.rs:2776

if key != "dependencies" || iter.next().is_some() {
            bail!(
                "NPM manifest found at `{}` can currently only have one key, \
                 `dependencies`, and no other fields",
                path.display()
            );
}

My Wasm module is cohabiting with a Typescript package, so I did what most would do, npm init, this means I share this package with several other libraries and test tools. I understand the philosophy of pay for only what you use and minimalism but, the package.json should be out of scope, it is not in Rusts domain. I would trust npm do its validating checks. Unless I am missing something critical I don't understand this check at all, what happens if I just delete it?

Happy to PR this, just not contributed to anything before.

[alexcrichton]

@adam-cyclones yep that sounds like the right spot, and it should likely be pretty safe to just delete.

[adam-cyclones]

Sorry I started a new job, have been preoccupied. Glad it's closed 😁

On Tue, 21 Jan 2020, 7:04 pm Alex Crichton, [e-mail]
wrote:

Closed #1921 https://github.com/rustwasm/wasm-bindgen/issues/1921 via

1969 https://github.com/rustwasm/wasm-bindgen/pull/1969.

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