Use wslview on WSL even when gio is installed

[rgwood]

This PR fixes a bug I've been experiencing on WSL.

I have gio installed in my WSL environment because it comes bundled with glib. Because of this, open-rs attempts to use gio and fails:

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: "Launcher \"gio\" \"open\" \"https://google.com\" failed with ExitStatus(unix_wait_status(512))" }', examples/website.rs:4:38
stack backtrace:
   0: rust_begin_unwind
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/std/src/panicking.rs:575:5
   1: core::panicking::panic_fmt
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/panicking.rs:65:14
   2: core::result::unwrap_failed
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/result.rs:1791:5
   3: core::result::Result<T,E>::unwrap
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/result.rs:1113:23
   4: website::main
             at ./examples/website.rs:4:5
   5: core::ops::function::FnOnce::call_once
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/ops/function.rs:251:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

To solve this, this PR just reorders the launchers used on unix so that wslview is attempted first. I think this is desirable behaviour because if wslview is present we're almost certainly in WSL.

If you foresee any problems with this approach, I could rewrite this to check whether we're in WSL before attempting to use wslview.

[Byron]

Thanks a lot for bringing this up!

Reordering linux launchers to do better on Windows Subsystem for Linux seems like a bias that would disadvantage the typical linux system which now have to pay for an extra command invocation attempt.

However, an additional file check seems cheap enough and will improve compatibility.

If the above works, could you adjust the PR accordingly or find a cheap way to test for WSL?

Thanks a lot.

[rgwood]

Sure thing, I've updated the PR so it will only attempt to run wslview when running in WSL.

I've looked into this space before and I believe the is-wsl crate is the best way to do this check. It's maintained by Sean Larkinn at Microsoft; I have reviewed the crate's code (and contributed to it). The author is actively maintaining it (unlike the older wsl crate). It caches the result with once_cell so we'll only pay the cost once.

I ran cargo bloat before+after this PR and it seems like it adds about 13KB to the open executable on Linux:

[Byron]

Thanks a lot, especially for the due diligence!

I have additionally limited the is-wsl dependency to be only for unix.

And now there is a new release with the fix as well.