Environment variables are broken

[syrusakbary]

I just encountered this issue when updating @wasmer/wasi to be compatible with wasi_snapshot_preview1).

Having this file:

use std::env;

fn main() {
    let existing = env::var_os("WASM_EXISTING");
    println!("should be set (WASM_EXISTING): {:?}", existing);
    let unexisting = env::var_os("WASM_UNEXISTING");
    println!("shouldn't be set (WASM_UNEXISTING): {:?}", unexisting);

    env::set_var("WASM_EXISTING", "NEW_VALUE");
    let existing = env::var_os("WASM_EXISTING");
    println!("Set existing var (WASM_EXISTING): {:?}", existing);
    env::set_var("WASM_UNEXISTING", "NEW_VALUE");
    let unexisting = env::var_os("WASM_UNEXISTING");
    println!("Set unexisting var (WASM_UNEXISTING): {:?}", unexisting);

    println!("All vars in env:");
    for (key, value) in env::vars() {
        println!("{}: {}", key, value);
    }
}

Compiling it with rustc env.rs --target wasm32-wasi -O

If running it without env vars:

wasmer packages/wasi/test/rs/wasi_snapshot_preview1/env.wasm

This will show the correct output:

should be set (WASM_EXISTING): None
shouldn't be set (WASM_UNEXISTING): None
Set existing var (WASM_EXISTING): Some("NEW_VALUE")
Set unexisting var (WASM_UNEXISTING): Some("NEW_VALUE")
All vars in env:
WASM_EXISTING: NEW_VALUE
WASM_UNEXISTING: NEW_VALUE

However, the following will fail (without printing anything) with error code 71:

wasmer packages/wasi/test/rs/wasi_snapshot_preview1/env.wasm --env "WASM_EXISTING=VALUE"

Note: this issue is independent of the runtime, it also happens in any other runtimes

[MarkMcCaskey]

I believe this was fixed in #159 but hasn't made it to stable Rust yet

[syrusakbary]

Yeah, thanks for pointing it @MarkMcCaskey!

[syrusakbary]

(to the maintainers: feel free to close this issue if is no longer relevant)

[tschneidereit]

@MarkMcCaskey, thanks for clearing this up!