Co-Authored-By: Daniel Silverstone <dsilvers@digital-scurf.org>

The example claims SuperiorThanZero and presumably Zero is not Superior than itself so it should not be allowed.

the docs are great at explaining that .len() isn't like in other
languages but stops short of explaining how to get the character length.

r? @steveklabnik

…encing the current trait

…ferencing the current trait

Just to make it useable for profiling and such inside
rustc itself.  It was vaguely useful in
https://wiki.alopex.li/WhereRustcSpendsItsTime and I figured
I might as well upstream it; I may or may not ever get around
to doing more with it (hopefully I will), but it may be useful
for others.

These errors are suboptimal, but they will be fixed by the new
`check_consts` pass.

…an-DPC

Update codegen option documentation.

Some documentation updates:

- Add more detail to codegen options.
- Add missing options:
    - `force-frame-pointers`
    - `default-linker-libraries`
    - `linker-plugin-lto`
- Add fragment anchors for all command-line-arguments.
- Add some cross links between options.

…Centril

docs: improve disclaimer regarding LinkedList

…=rkruppe

Add FFI bindings for LLVM's Module::getInstructionCount()

Just to make it usable for profiling and such inside
rustc itself.  It was vaguely useful in
https://wiki.alopex.li/WhereRustcSpendsItsTime and I figured
I might as well upstream it; I may or may not ever get around
to doing more with it (hopefully I will), but it may be useful
for others.

[doc] fixes for unix/vxworks `OpenOptionsExt::mode`

Fix logic in example.

The example claims SuperiorThanZero and presumably Zero is not Superior than itself so it should not be allowed.

…=Mark-Simulacrum

Improved std::iter::Chain documentation

Replaces `strings two iterators` by `links two iterators` in `std::iter::Chain` documentation.

I didn't find any meaning of `strings` which can be evaluated as `links` or `joins`.

I don't think that `std::iter:Chain` works as a stringer or plays billiards. (https://www.lexico.com/en/definition/string).

doc(str): show example of chars().count() under len()

the docs are great at explaining that .len() isn't like in other
languages but stops short of explaining how to get the character length.

…-ref-current-trait, r=estebank

Suggest correct code when encountering an incorrect trait bound referencing the current trait

Fixes rust-lang#65985 and also improves the suggestion for code like this:

```
trait Grab {
    type Value;
    fn grab(&self) -> Grab::Value;
}
```

To suggest `<Self as Grab>::Value`.

I wasn't sure which of the syntax versions is better (`<Self as ..>::` vs `Self::`), so I used the former simply because it was less change to the existing code.

r? @estebank

…ntril

Do not needlessly write-lock

Just removes a needless `borrow_mut()` by using `borrow()` instead.

…entril

Add a failing UI test for multiple loops of all kinds in a `const`

This simply demonstrates the current behavior and ensures we don't allow anything by accident.

The new const checker will be able to improve the diagnostics here. While working on it, I didn't see very many tests with non-`while` loops in a `const`, and there were no tests with multiple loops.