Replace FnBox with Box<dyn FnOnce>

[vorot93]

FnBox has been removed, this commit fixes the build with the latest nightly.

[gnzlbg]

Note that this libtest is not the test crate in rust-lang/rust.

[gnzlbg]

It makes little sense to make changes to this crate, since all of them will need to be reverted when trying to replace the libtest in rust-lang/rust with this crate again.

[gnzlbg]

If you want to work on achieving that, please let me know, and I can mentor.

[vorot93]

I don't understand. libtest at crates.io says this is the repository. And the crate is used by the larger ecosystem. Therefore fixing code here and publishing it should fix the broken builds, right?

[tikue]

@gnzlbg should crates not be depending on libtest at this time? e.g. should I revert google/tarpc#213?

[gnzlbg]

I don't understand. libtest at crates.io says this is the repository.

The libtest at crates.io doesn't say much really, and the released version is 0.0.1. When the process is finished, there will be an announcement, and version 1.0 will be released.

We should probably add a note to the readme saying that, but we can't yank the repo because we need it in crates.io to be able to migrate rustc to it.

@gnzlbg should crates not be depending on libtest at this time?

Depends on the crate. There are certain crates inside rustc, miri, clippy, etc. that can depend on it, but at the moment is still for internal consumption only. The proper way to access this is by just writing extern crate test and using the feature(test) nightly feature.