`getrandom` is duplicated in `ic-vetkeys` dependencies, causing build failures

[ranile]

getrandom 0.2 is a hard dependency of ic-vetkeys package. When building a package with the dependency

ic-vetkeys = { git = "https://github.com/dfinity/vetkeys" }

it fails with the following error:

error: the wasm*-unknown-unknown targets are not supported by default, you may need to enable the "js" feature. For more information see: https://docs.rs/getrandom/#webassembly-support
   --> ~/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/getrandom-0.2.16/src/lib.rs:346:9
    |
346 | /         compile_error!("the wasm*-unknown-unknown targets are not supported by \
347 | |                         default, you may need to enable the \"js\" feature. \
348 | |                         For more information see: \
349 | |                         https://docs.rs/getrandom/#webassembly-support");
    | |________________________________________________________________________^

error[E0433]: failed to resolve: use of unresolved module or unlinked crate `imp`
   --> ~/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/getrandom-0.2.16/src/lib.rs:402:9
    |
402 |         imp::getrandom_inner(dest)?;
    |         ^^^ use of unresolved module or unlinked crate `imp`
    |
    = help: if you wanted to use a crate named `imp`, use `cargo add imp` to add it to your `Cargo.toml`

Workaround

for anyone stumbling upon, the workaround looks like:

Cargo.toml

[dependencies]
getrandom_03 = { version = "0.3.3", package = "getrandom" }
getrandom_02 = { version = "0.2", package = "getrandom", features = ["custom"] }

lib.rs

#[unsafe(no_mangle)]
unsafe extern "Rust" fn __getrandom_v03_custom(
    _dest: *mut u8,
    _len: usize,
) -> Result<(), getrandom_03::Error> {
    Err(getrandom_03::Error::UNSUPPORTED)
}

pub fn always_fail_02(_buf: &mut [u8]) -> Result<(), getrandom_02::Error> {
    Err(getrandom_02::Error::UNSUPPORTED)
}

getrandom_02::register_custom_getrandom!(always_fail_02);

[randombit]

Thanks for raising the issue. Unfortunately it is nearly impossible to remove getrandom as a dependency since many crates depend on rand without specifying default-features = false, and if we depend on even a single one of those crates, even as a dev-dependency, feature unification results in depending on getrandom in the production binary. And getrandom's refusal to compile on wasm32-unknown-unknown is a deliberate choice on the part of the getrandom developers, one which they seem uninterested in revisiting.

For getrandom 0.2 a workaround very similar to to the one you suggest is included in https://crates.io/crates/ic-dummy-getrandom-for-wasm; this crate is commonly used within DFINITY to avoid the problem of getrandom when compiling a canister written in Rust.

[ranile]

For getrandom 0.2 a workaround very similar to to the one you suggest is included in https://crates.io/crates/ic-dummy-getrandom-for-wasm; this crate is commonly used within DFINITY to avoid the problem of getrandom when compiling a canister written in Rust.

I actually saw that crate in the dependencies of an example in this repo and decided to base my workaround off of it. I didn't directly add that crate because I need to workaround for getrandom 0.3 as well and the said crate only adds a workaround for 0.2