docs.rs macOS and wasm32 builds failing

[kpreid]

With wgpu 0.18, the macOS and wasm32 targets no longer build on docs.rs as they did in previous versions. rust-lang/docs.rs#2424 (comment) retrieved the details:

Trying cargo rustdoc --target wasm32-unknown-unknown locally gives an explicit compile_error!:

error: webgpu feature used without web_sys_unstable_apis config:
       Here are some ways to resolve this:
       * If you wish to use webgpu backend, create a .cargo/config.toml in the root of the repo containing:
           [build]
           rustflags = [ "--cfg=web_sys_unstable_apis" ]
           rustdocflags = [ "--cfg=web_sys_unstable_apis" ]
       * If you wish to disable webgpu backend and instead use webgl backend, change your wgpu Cargo.toml entry to:
           wgpu = { version = "", default-features = false, features = ["webgl"] }
  --> src/backend/mod.rs:7:1
   |
7  | / compile_error!(
8  | |     "webgpu feature used without web_sys_unstable_apis config:
9  | | Here are some ways to resolve this:
10 | | * If you wish to use webgpu backend, create a .cargo/config.toml in the root of the repo containing:
...  |
16 | | "
17 | | );
   | |_^

while x86_64-apple-darwin appears to fail to cross-compile a dependency

warning: objc_exception@0.1.2: gcc: error: unrecognized command-line option ‘-arch’
warning: objc_exception@0.1.2: gcc: error: unrecognized command-line option ‘-mmacosx-version-min=10.7’

error: failed to run custom build command for `objc_exception v0.1.2`

So, at least, the docs.rs metadata in wgpu/Cargo.toml should be updated to include building with --cfg=web_sys_unstable_apis. I don't know what would be doable for the macOS build.

[cwfitzgerald]

Way ahead of you :) This fixes the wasm issue #5310 and gfx-rs/metal-rs#303 should make metal compile again