… crate

Partly address rust-lang#78543 by making the error quieter.

We don't have access to the `typeck` tables from foreign crates, so we
used to completely skip the new code when checking foreign crates. Now,
we carry on and don't provide as nice output (we don't clarify *what* is
making the `Future: !Send`), but at least we no longer emit a sea of
derived obligations in the output.

[1]: https://blog.rust-lang.org/inside-rust/2019/10/11/AsyncAwait-Not-Send-Error-Improvements.html

Both style-check and date-check are now on the 2021 edition, and this
commit also updates their repositories' submodules.

…n-future, r=tmandry

Use the "nice E0277 errors"[1] for `!Send` `impl Future` from foreign crate

Partly address rust-lang#78543 by making the error quieter.

We don't have access to the `typeck` tables from foreign crates, so we
used to completely skip the new code when checking foreign crates. Now,
we carry on and don't provide as nice output (we don't clarify *what* is
making the `Future: !Send`), but at least we no longer emit a sea of
derived obligations in the output.

[1]: https://blog.rust-lang.org/inside-rust/2019/10/11/AsyncAwait-Not-Send-Error-Improvements.html

r? `@tmandry`

Do not mention a reexported item if it's private

Fixes rust-lang#90113
The _actual_ regression was introduced in rust-lang#73652, then rust-lang#88838 made it worse. This fixes the issue by not counting such an import as a candidate.

…Simulacrum

tidy: Remove submodules from edition exception list

Both style-check and date-check are now on the 2021 edition, and this
PR also updates their repositories' submodules.

cc rust-lang/rustc-dev-guide#1238
cc rust-lang/reference#1099
cc rust-lang#89103 (comment)

…k-Simulacrum

Add alias for [email protected]

Hopefully it'll stop making me appear twice in the thanks page. :)