How to use per-project wasm-bindgen-cli version?

[demurgos]

Summary

I have two projects on my computer depending on WasmBindgen, but requiring different versions. How can I specify and pin the right wasm-bindgen-cli version on a per-project basis so it always matches the corresponding wasm-bindgen lib version?

Additional Details

My first Cargo.toml contains:

[target.'cfg(target_arch = "wasm32")'.dependencies]
wasm-bindgen = "=0.2.67"

My second Cargo.toml was freshly updated and contains:

[target.'cfg(target_arch = "wasm32")'.dependencies]
wasm-bindgen = "=0.2.78"

On my system I have a single global wasm-bindgen installation:

$ wasm-bindgen --version
wasm-bindgen 0.2.67

I can't compile the recently updated project:

thread 'main' panicked at 'remaining data [19]', /home/demurgos/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wasm-bindgen-cli-support-0.2.67/src/descriptor.rs:109:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

So I updated my globally installed wasm-bindgen CLI as documented:

cargo install -f wasm-bindgen-cli

But now I can't build my older project:

thread 'main' panicked at 'index out of bounds: the len is 0 but the index is 0', /home/demurgos/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wasm-bindgen-cli-support-0.2.78/src/descriptor.rs:205:15
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

I believe that those are some relevant Cargo issues, but I feel that there is no good solution at the moment. How do you handle this problem for your own projects?

• Proposal: allow crates to depend on a binary crate #4316
• If you depend on a binary then commands are inconsistent #8708
• Support for bin build-dependency #8873
• Tracking Issue for RFC 3028: Allow "artifact dependencies" on bin, cdylib, and staticlib crates #9096

[chinedufn]

That

thread 'main' panicked at 'index out of bounds: the len is 0 but the index is 0', /home/demurgos/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wasm-bindgen-cli-support-0.2.78/src/descriptor.rs:205:15

error is unfortunate. Versions 2.78+ have a better error message than that. You're seeing that because the old project is <2.78. Sorry!

---

The most popular way that people handle this right now is by using wasm-pack or by updating old projects whenever wasm-bindgen's internal schema changes (infrequent).

Some potential options for you:

1. Download the release binaries that you need and use them accordingly

2. OR use or write something like wasm-pack. It checks your Cargo.toml to figure out the necessary CLI version and then downloads it.

[demurgos]

Thank you for your reply, I will look into these solutions.

[alexcrichton]

I don't have much to add over what @chinedufn already said (thanks!), so I'm going to close.

[zopsicle]

You can depend on wasm-bindgen-cli-support using regular Cargo dependencies and then write your own binary, like this:

use wasm_bindgen_cli_support::Bindgen;

fn main()
{
    Bindgen::new()
        .input_path("my-wasm-file.wasm")
        .generate("my-out-dir")
        .unwrap();
}

[demurgos]

@chloekek Thank you very much, using wasm-bindgen-cli-support in a local bin wrapper works great and lets me version it properly. :)