… code

When remapping a resume argument with projections rebase them on top of
the new base.

The case where resume argument has projections is unusual, but might
arise with box syntax where the assignment is performed directly into
the box without an intermediate temporary.

… type

Fixes rust-lang#89307

Do not suggest importing inaccessible items

Fixes rust-lang#88472. For this example:
```rust
mod a {
    struct Foo;
}

mod b {
    type Bar = Foo;
}
```
rustc currently emits:
```
error[E0412]: cannot find type `Foo` in this scope
 --> test.rs:6:16
  |
6 |     type Bar = Foo;
  |                ^^^ not found in this scope
  |
help: consider importing this struct
  |
6 |     use a::Foo;
  |
```
this is incorrect, as applying this suggestion leads to
```
error[E0603]: struct `Foo` is private
 --> test.rs:6:12
  |
6 |     use a::Foo;
  |            ^^^ private struct
  |
note: the struct `Foo` is defined here
 --> test.rs:2:5
  |
2 |     struct Foo;
  |     ^^^^^^^^^^^
```
With my changes, I get:
```
error[E0412]: cannot find type `Foo` in this scope
 --> test.rs:6:16
  |
6 |     type Bar = Foo;
  |                ^^^ not found in this scope
  |
  = note: this struct exists but is inaccessible:
          a::Foo
```
As for the wildcard mentioned in rust-lang#88472, I would argue that the warning is actually correct, since the import _is_ unused. I think the real issue is the wrong suggestion, which I have fixed here.

…=davidtwco

Detect when negative literal indices are used and suggest appropriate code

Rebase resume argument projections during state transform

When remapping a resume argument with projections rebase them on top of
the new base.

The case where resume argument has projections is unusual, but might
arise with box syntax where the assignment is performed directly into
the box without an intermediate temporary.

Fixes rust-lang#85635.

…eywiser

Pick one possible lifetime in case there are multiple choices

In case a lifetime variable is created, but doesn't have an obvious lifetime in the list of named lifetimes that it should be inferred to, just pick the first one for the diagnostic.

This happens e.g. in

```rust
fn foo<'a, 'b>(a: Struct<'a>, b: Struct<'b>) -> impl Trait<'a, 'b> {
    if bar() { a } else { b }
}
```

where we get a lifetime variable that combines the lifetimes of `a` and `b` creating a lifetime that is the intersection of both. Right now the type system cannot express this and thus we get an error, but that error also can't express this.

I can also create an entirely new diagnostic that mentions all involved lifetimes, so it would actually mention `'a` and `'b` instead of just `'b`.

Cleanup lower_generics_mut and make span be the bound itself

Closes rust-lang#86298 (supersedes those changes)

r? `@cjgillot` since you reviewed the other PR

(Used wrong branch for rust-lang#89338)

…r=cuviper

Update `llvm` submodule to fix function name mangling on x86 Windows

Fixes rust-lang#89307

Add regression test for issues rust-lang#88969 and rust-lang#89119

This adds a regression test to complete rust-lang#89125, and thus for issues rust-lang#88969 and rust-lang#89119, which needed a test.

Used with multiple crates, [this](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=f665e7e882059157e0f86cfb09c47187) minimized from `zvariant-2.8.0` reproduces the error on `nightly-2021-09-19`.

The test in this PR fails on master if the commit 6dbb9d4 from rust-lang#89125 is reverted, and passes otherwise since it's now fixed.

r? `@Aaron1011`