…d a long lost assertion

This reverts part of commit 9712fa4.

Co-Authored-By: Ralf Jung <[email protected]>

This bumps the commit of webrender we test to include a fix for a
spurious failure we encountered in CI. See rust-lang#69895 for more context on
the spurious failure.

Added tvOS as targets

This is a first attempt of adding support tvOS as described in rust-lang#48862. It's got a lot of overlap with [src/librustc_target/spec/apple_ios_base.rs](https://github.com/rust-lang/rust/blob/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/librustc_target/spec/apple_ios_base.rs).

I thought about refactoring `apple_ios_base.rs` to include this as well but that would require each of the ios and tvos targets to be of the something like the form `let base = opts(AppleOS::TV, Arch::Arm64)?;` I also did the same thing for watchOS because from what I can tell, all three targets (iOS, tvOS, and watchOS) have the same logic but have different parameters being sent to `xcrun`. Thoughts?

As far as the `data_layout` and other parameters to `Target`, I did as much research as I could but it really seems that processor in the [iPhone 11 is the same as the apple TV](https://en.wikipedia.org/wiki/Apple-designed_processors) so I didn't change any of those parameters.

I did get this to build and tested that it's actually running the the below logic (because the parameter to `xcrun` is `appletvos` not `tvos`).

I didn't manage to get it to actually compile a file with `fn main(){}` because I don't have the stdlib for `aarch64-apple-tvos` compiled it seems. Is there documentation for this?

Similar to the ending of rust-lang#63467, I'm not sure what to do next.

…rk-Simulacrum

Document unsafe blocks in core::fmt

r? @RalfJung
CC: @rust-lang/wg-unsafe-code-guidelines
rust-lang#66219

Sorry for the hiatus, but here's a few more files with the unsafe blocks documented! I think working on it smaller chunks like this will be easier for everyone.

…ta, r=Mark-Simulacrum

Toolstate: remove redundant beta-week check.

I made a bit of a mistake in rust-lang#69624.  The "beta regression" doesn't need to be checked twice.

I also rolled up rust-lang#69693 to avoid merge conflicts.

…Centril

Tweak output for invalid negative impl AST errors

Use more accurate spans for negative `impl` errors.

r? @Centril

…etroalbini

Rename rustc guide

This is in preparation for rust-lang/rustc-dev-guide#470
Needs to be merged after we actually rename the guide.

Have used this to rename:

`git grep -l 'rustc_guide' | xargs sed -i 's/rustc_guide/rustc_dev_guide/g'`
`git grep -l 'rustc-guide' | xargs sed -i 's/rustc-guide/rustc-dev-guide/g'`
`git grep -l 'rustc guide' | xargs sed -i 's/rustc guide/rustc dev guide/g'`

…lfJung

Compute the correct layout for variants of uninhabited enums

r? @eddyb
cc @RalfJung

fixes rust-lang#69191
cc rust-lang#69763

…=oli-obk

miri: ICE on invalid terminators

We've run a lot of MIR in Miri (including some generators) and never seen these.

@tmandry is it correct that `Yield` and `GeneratorDrop` get lowered away?

@eddyb @oli-obk what's with this `Abort` that does not seem to ever actually exist? Codegen *does* seem to handle it, so I wonder why Miri can get away without that. In fact, codegen handles it twice:

https://github.com/rust-lang/rust/blob/1d5241c96208ca7d925442b1a5fa45ad18717a6f/src/librustc_codegen_ssa/mir/block.rs#L796

https://github.com/rust-lang/rust/blob/1d5241c96208ca7d925442b1a5fa45ad18717a6f/src/librustc_codegen_ssa/mir/mod.rs#L296

rustdoc: remove unused import

```
    Checking rustdoc v0.0.0 (/home/matthias/vcs/github/rust/src/librustdoc)
warning: unused import: `rustc_span::symbol::sym`
  --> src/librustdoc/clean/inline.rs:15:5
   |
15 | use rustc_span::symbol::sym;
   |     ^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_imports)]` on by default
```

…er, r=Mark-Simulacrum

ci: bump webrender in cargotest

This bumps the commit of webrender we test to include a fix for a spurious failure we encountered in CI. See rust-lang#69895 for more context on the spurious failure.

The commit we're interested in including is servo/webrender@07439c5. Thanks again @jrmuizel for the quick response on this!

r? @Mark-Simulacrum