…r=Amanieu

`Split*::as_str` refactor

I've made this patch almost a year ago, so the rename and the behavior change are in one commit, sorry 😅

This fixes #84974, as it's required to make other changes work.

This PR
- Renames `as_str` method of string `Split*` iterators to `remainder` (it seems like the `as_str` name was confusing to users)
- Makes `remainder` return `Option<&str>`, to distinguish between "the iterator is exhausted" and "the tail is empty", this was [required on the tracking issue](rust-lang/rust#77998 (comment))

r? `@m-ou-se`

Only specify `--target` by default for `-Zgcc-ld=lld` on wasm

On macOS, it's not yet clear which cases of clang/OS/target/SDK version impact how to find ld/lld/rust-lld. The `--target` argument is not needed on our current targets with a vanilla config to do so, but may be in some cases ?

That is, things look to be different and more subtle than suggested in rust-lang/rust#97402 (comment).

Specifying this argument unconditionally currently breaks `-Zgcc-ld=lld` on the 10.7+ targets on x64 macOS. Vanilla configs on x64 and aarch64 don't seem to need it to be able to find `rust-lld`.

This fixes #101653 on macOS (I've tried on x64 and aarch64: vanilla installs with the most recent command line tools available for each of the OS versions I have access to, `run-make/issue-71519` passes).

I didn't expect the previous PRs to fail because of the existing tests, but CI does not actually run those tests yet, which explains the regressions. I was hoping to fix those in this PR but it's more involved (building lld is required for the tests to run, llvm/lld is not built on the test builders but on the dist builders, the dist builders don't run tests). This PR is just to unblock current users on macOS who have reported issues, but a regression could happen in the future by mistake until then.

r? `@petrochenkov`

…mpiler-errors

Refactoring report_method_error

While working on #105732, I found it's hard to follow this long function,
so I tried to make it shorter.

It's not easy for code reviewing, since so many lines of code changes,
but only the positions are changed.

Generally, I extract two sub-methods from `report_method_error`:

https://github.com/rust-lang/rust/blob/397b66e77b279de5006facf87979f9ecff5c7f87/compiler/rustc_hir_typeck/src/method/suggest.rs#L117
to `note_candidates_on_method_error`

And this long block:
https://github.com/rust-lang/rust/blob/397b66e77b279de5006facf87979f9ecff5c7f87/compiler/rustc_hir_typeck/src/method/suggest.rs#L263

to `report_no_match_method_error`.

r? `@compiler-errors`

PlayStation Vita support

Just the compiler definitions for no-std projects and std support using newlib

Earlier PR: rust-lang/rust#105606

Deallocate ThinBox even if the value unwinds on drop

This makes it match the behavior of an ordinary `Box`.

Fix handling of dead unwinds in backward analyses

Dead unwinds set contains a head of an unreachable unwind edge.

Small fixes for --crate-type staticlib

The first commit doesn't have an effect until we start translating error messages. The second commit fixes potential linker errors when combining `--crate-type staticlib` with another crate type and I think `-Cprefer-dynamic`.

Don't deduce a signature that makes a closure cyclic

Sometimes when elaborating supertrait bounds for closure signature inference, we end up deducing a closure signature that is cyclical because either a parameter or the return type references a projection mentioning `Self` that also has escaping bound vars, which means that it's not eagerly replaced with an inference variable.

Interestingly, this is not *just* related to my PR that elaborates supertrait bounds for closure signature deduction. The committed test `supertrait-hint-cycle-3.rs` shows **stable** code that is fixed by this PR:

```rust
trait Foo<'a> {
    type Input;
}

impl<F: Fn(u32)> Foo<'_> for F {
    type Input = u32;
}

fn needs_super<F: for<'a> Fn(<F as Foo<'a>>::Input) + for<'a> Foo<'a>>(_: F) {}

fn main() {
    needs_super(|_: u32| {});
}
```

Fixes #105401
Fixes #105396

r? types

Remove duplicated elaborate box derefs pass

The pass runs earlier as a part of `run_runtime_lowering_passes`.

The duplicate was added in #99102.

Fix --kbd-color variable name in rustdoc.css

Interestingly enough, it only impacted the dark theme.

Before:

![Screenshot from 2023-01-05 11-03-17](https://user-images.githubusercontent.com/3050060/210754145-c3bb0f50-d35f-4543-bf73-010a4524a803.png)

After:

![Screenshot from 2023-01-05 11-03-05](https://user-images.githubusercontent.com/3050060/210754190-85c2f146-a774-4463-9cd3-9495b7c91bd7.png)

r? `@notriddle`

Add help diag. for `const = Enum` missing braces around `Enum`

Previously it was not clear why this errored or if it was even supported, as there was no diagnostic that suggested wrapping it in braces.

Thus, add a simple diagnostic that suggests wrapping enum variants in braces.

Fixes #105927

Perform SimplifyLocals before ConstProp.

MIR before `ConstProp` may have a lot of dead writes, this makes `ConstProp` do unnecessary work.

r? `@ghost`

…avidtwco

Rework `Bounds` collection

I think it's weird for the `Bounds` struct in astconv to store its predicates *almost* converted into real predicates... so we do this eagerly, instead of lazily.

…=Mark-Simulacrum

Add retry mechanism for rustdoc GUI tests to reduce flakyness

Part of #93784.

I added 3 retries for failing GUI tests. An important note: if more than half of total tests fail, I don't retry because it's very likely not flakyness anymore at this point but a missing update after changes.