Cargo doesn't build winit with nokhwa bc of web-sys dependency

Question

I have a winit crate based Rust project, to which I want to add the nokhwa crate too, but now cargo doesn't even compile it, because of some weird dependency error:

error: failed to select a version for `web-sys`.
    ... required by package `wgpu v0.11.0`
    ... which satisfies dependency `wgpu = "^0.11"` of package `nokhwa v0.9.4`
    ... which satisfies dependency `nokhwa = "^0.9.4"` of package `winit_wgpu_test v0.1.0 (C:\schabby\Rust\winit_wgpu_test)`
versions that meet the requirements `^0.3.53` are: 0.3.67, 0.3.66, 0.3.65, 0.3.64, 0.3.63, 0.3.62, 0.3.61, 0.3.60, 0.3.59, 0.3.58, 0.3.57, 0.3.56, 0.3.55, 0.3.54, 0.3.53

the package `wgpu` depends on `web-sys`, with features: `GpuBufferUsage` but `web-sys` does not have these features.


all possible versions conflict with previously selected packages.

  previously selected package `web-sys v0.3.64`
    ... which satisfies dependency `web-sys = "^0.3.53"` of package `wgpu v0.11.0`
    ... which satisfies dependency `wgpu = "^0.11"` of package `nokhwa v0.9.4`
    ... which satisfies dependency `nokhwa = "^0.9.4"` of package `winit_wgpu_test v0.1.0 (C:\schabby\Rust\winit_wgpu_test)`

failed to select a version for `web-sys` which could resolve this conflict

this is my cargo.toml:

[dependencies]
env_logger = "0.10.0"
pollster = "0.3.0"
winit = { version = "0.29.10", features = ["rwh_05"]}

[dependencies.nokhwa]
version = "0.9.4"
features = ["input-msmf", "output-wgpu"]

NOTE: Yes, with the latest version of nokhwa it's not a problem, but I have to use nokhwa 0.9.4, because in the newer versions the "output-wgpu" feature is broken, which I need.

What I understood is that in web-sys, the 'GpuBufferUsage' feature was renamed to 'gpu_buffer_usage' (I found out from here : https://www.reddit.com/r/rust/comments/xcsls9/comment/io8pmam/ )

Moreover, in the relevant part of web-sys source code - https://rustwasm.github.io/wasm-bindgen/api/src/web_sys/features/gen_gpu_buffer_usage.rs.html - I see this:

#[cfg(web_sys_unstable_apis)]
    #[doc = "The `GPUBufferUsage.MAP_READ` const."]
    #[doc = ""]
    #[doc = "*This API requires the following crate features to be activated: `gpu_buffer_usage`*"]
    #[doc = ""]
    #[doc = "*This API is unstable and requires `--cfg=web_sys_unstable_apis` to be activated, as"]
    #[doc = "[described in the `wasm-bindgen` guide](https://rustwasm.github.io/docs/wasm-bindgen/web-sys/unstable-apis.html)*"]

So, I tried to build my project with --cfg=web_sys_unstable_apis enabled, but to no avail. I tried it by setting a global environment variable (restarted computer) and in PowerShell (I'm on Windows 11) like this:

$env:CARGO_ENCODED_RUSTFLAGS="--cfg=web_sys_unstable_apis"; cargo build

or even in my cargo.toml like:

[build]
CARGO_ENCODED_RUSTFLAGS = "--cfg=web_sys_unstable_api"

and even using simply RUSTFLAGS instead of CARGO_ENCODED_RUSTFLAGS, but everything is the same.

Any idea how to solve this?

Answer 1

In this specific case you only have to options:

1. Make a PR against the v0.11 branch of wgpu and change the renamed feature (requiring you to update the web-sys crate to a newer version). This will then also require a release to crates.io, which is why it might be desirable for you to use a local patch version or one from your own repo (e.g. fork of winit v0.11).
2. Use winit version 0.28.x, because this way web-sys v0.3.53 (which does have the GpuBufferUsage feature; among others) can still be used with winit.