Old version (1.x) of the slog crate can't compile

[pietroalbini]

This was caught in crater thanks to shadowsocks (crater log), which uses an old release of slog (1.0). This works fine on stable, but fails on beta and nightly.

   Compiling slog v1.3.2
error[E0277]: the trait bound `*mut core::ops::Fn() + 'static: core::marker::Sync` is not satisfied in `core::fmt::Arguments<'static>`
   --> /home/pietro/.cargo/registry/src/github.com-1ecc6299db9ec823/slog-1.3.2/src/ser.rs:228:6
    |
228 | impl SyncSerialize for fmt::Arguments<'static> {}
    |      ^^^^^^^^^^^^^ `*mut core::ops::Fn() + 'static` cannot be shared between threads safely
    |
    = help: within `core::fmt::Arguments<'static>`, the trait `core::marker::Sync` is not implemented for `*mut core::ops::Fn() + 'static`
    = note: required because it appears within the type `core::marker::PhantomData<*mut core::ops::Fn() + 'static>`
    = note: required because it appears within the type `core::fmt::Void`
    = note: required because it appears within the type `&'static core::fmt::Void`
    = note: required because it appears within the type `core::fmt::ArgumentV1<'static>`
    = note: required because it appears within the type `[core::fmt::ArgumentV1<'static>]`
    = note: required because it appears within the type `&'static [core::fmt::ArgumentV1<'static>]`
    = note: required because it appears within the type `core::fmt::Arguments<'static>`

cc @dpc

[dtolnay]

I believe this is expected from the soundness fix in #45198. The fix exposed legitimately unsound use of fmt::Arguments in those versions of slog. We coordinated with the slog author to publish a fix in slog before landing the fix on the rustc side.

[kennytm]

shadowsocks's slog dependency needs to be updated from ~1.3 to 1.7.1, or preferably to 2.1.1.

cc @loggerhead.

[pietroalbini]

bomgar/rust-oauth-proxy (crater log) and epage/relint (crater log) also depend on an old version of slog, which needs to be updated to 1.7.1 or 2.1.1. cc @bomgar @epage

woodpecker also regressed, not related to slog though (crater log). cc @niamster

[epage]

Don't worry about relint atm. Its not yet in a usable state and I've not been working to get it there with some of the other stuff on my plate.

If there isn't a nice way for you all to resolve it, I can do whatever you recommend to appease crater.

[pietroalbini]

If you don't plan to fix it it's fine: crater is currently marking it as regressed because it builds fine on stable but fails on beta, and after the next stable is released it should stop complaining about it.

[loggerhead]

Thanks, I have changed the version of slog to fix this issue.