support fixed toolchain

[oligamiq]

In this way, the tool chain version can be fixed.
https://rust-lang.github.io/rustup/concepts/toolchains.html

Reason:
The rust-pack uses wasm32-unknown-unknown, but this target is automatically enabled for functionality during version upgrades. The currently enabled features are enabled in all major browsers, but are mainly yoked to the LLVM side and may be enabled before they are supported in all browsers.

Therefore, it is necessary to manually enable them in wasm32v1-none or fix the version of rust.

As far as Cargo.lock is concerned, the one previous library is the wasm when multivalue is not enabled. However, when compiled with the current version of Rust, it is likely that the wasm will be changed, such as multivalue being enabled, so it is also necessary to mark this as a difference between versions.

ref:
https://rustwasm.github.io/docs/wasm-pack/prerequisites/non-rustup-setups.html
https://doc.rust-lang.org/stable/rustc/platform-support/wasm32v1-none.html
https://doc.rust-lang.org/stable/rustc/platform-support/wasm32-unknown-unknown.html#enabled-webassembly-features
https://developer.mozilla.org/en-US/docs/WebAssembly

[pimterry]

Sure, pinning the Rust version seems reasonable to me. I'm not sure about the conventions for that but very happy to accept a PR to do so in whatever way is most reasonable.

It'd be good to make sure this is handled correctly in the CI build too, which automatically installs the latest toolchain at the moment every build.

[oligamiq]

The link was incorrect.
The correct link is https://rust-lang.github.io/rustup/overrides.html#the-toolchain-file

ex.
rust-toolchain.toml

[toolchain]
channel = "1.70.0"
components = ["rustc", "cargo"]
profile = "minimal"
targets = []

[oligamiq]

Compilation failed, I reverted the Rust version to 1.70.0 to cope, but I still think the toolchain should be fixed.

npm run build

> brotli-wasm@3.0.1 build
> node ./build.js

[INFO]: Checking for the Wasm target...
[INFO]: Compiling to Wasm...
   Compiling wasm-bindgen v0.2.80
error: older versions of the `wasm-bindgen` crate are incompatible with current versions of Rust; please update to `wasm-bindgen` v0.2.88

error: could not compile `wasm-bindgen` (lib) due to 1 previous error
Error: Compiling your crate to WebAssembly failed
Caused by: failed to execute `cargo build`: exited with exit code: 101
  full command: "cargo" "build" "--lib" "--release" "--target" "wasm32-unknown-unknown"
mv: no such file or directory: pkg
rm: no such file or directory: pkg.bundler/{LICENSE,package.json,README.md,.gitignore}
[INFO]: Checking for the Wasm target...
[INFO]: Compiling to Wasm...
   Compiling wasm-bindgen v0.2.80
error: older versions of the `wasm-bindgen` crate are incompatible with current versions of Rust; please update to `wasm-bindgen` v0.2.88

error: could not compile `wasm-bindgen` (lib) due to 1 previous error
Error: Compiling your crate to WebAssembly failed
Caused by: failed to execute `cargo build`: exited with exit code: 101
  full command: "cargo" "build" "--lib" "--release" "--target" "wasm32-unknown-unknown"
mv: no such file or directory: pkg
rm: no such file or directory: pkg.node/{LICENSE,package.json,README.md,.gitignore}
[INFO]: Checking for the Wasm target...
[INFO]: Compiling to Wasm...
   Compiling wasm-bindgen v0.2.80
error: older versions of the `wasm-bindgen` crate are incompatible with current versions of Rust; please update to `wasm-bindgen` v0.2.88

error: could not compile `wasm-bindgen` (lib) due to 1 previous error
Error: Compiling your crate to WebAssembly failed
Caused by: failed to execute `cargo build`: exited with exit code: 101
  full command: "cargo" "build" "--lib" "--release" "--target" "wasm32-unknown-unknown"
mv: no such file or directory: pkg
rm: no such file or directory: pkg.web/{LICENSE,package.json,README.md,.gitignore}

[pimterry]

I still think the toolchain should be fixed

PRs welcome. There was a past attempt to update this in #42 which has stalled, but did suggest that adding wasm-opt = false might be useful.