…t types

The `incoming` method is really useful, however for some use cases the borrow
this introduces is needlessly restricting. Thus, an owned variant is added.

In some cases, we emit borrowcheck diagnostics pointing
at a particular field expression in a struct expression
(e.g. `MyStruct { field: my_expr }`). However, this
behavior currently relies on us choosing the
`ConstraintCategory::Boring` with the 'correct' span.
When adding additional variants to `ConstraintCategory`,
(or changing existing usages away from `ConstraintCategory::Boring`),
the current behavior can easily get broken, since a non-boring
constraint will get chosen over a boring one.

To make the diagnostic output less fragile, this commit
adds a `ConstraintCategory::Usage` variant. We use this variant
for the temporary assignments created for each field of
an aggregate we are constructing.

Using this new variant, we can emit a message mentioning
"this usage", emphasizing the fact that the error message
is related to the specific use site (in the struct expression).

This is preparation for additional work on improving NLL error messages
(see rust-lang#57374)

…nimplemented

This isn't allowed by the validator, and seems to be unused.
When it was added in ed10a3f,
it was used on `Sized`, and that usage is gone.

Fixes issue rust-lang#88927.

CC rust-lang#51430

rust-lang/backtrace-rs#437 fixed backtraces in
OpenBSD -> update it here as well so OpenBSD Rust code can produce
proper backtraces.

…:MirPass public

…akis

Fix ICE in `improper_ctypes_definitions` lint with all-ZST transparent types

Fixes rust-lang#87496. There is also another function in the same file that looks fishy, but I haven't been able to produce an ICE there, and in any case, it's not related to rust-lang#87496:
https://github.com/rust-lang/rust/blob/fd853c00e255559255885aadff9e93a1760c8728/compiler/rustc_lint/src/types.rs#L720-L734

r? ``@JohnTitor``

Add TcpListener::into_incoming and IntoIncoming

The `incoming` method is really useful, however for some use cases the borrow
this introduces is needlessly restricting. Thus, an owned variant is added.

r? `@joshtriplett`

Add `ConstraintCategory::Usage` for handling aggregate construction

In some cases, we emit borrowcheck diagnostics pointing
at a particular field expression in a struct expression
(e.g. `MyStruct { field: my_expr }`). However, this
behavior currently relies on us choosing the
`ConstraintCategory::Boring` with the 'correct' span.
When adding additional variants to `ConstraintCategory`,
(or changing existing usages away from `ConstraintCategory::Boring`),
the current behavior can easily get broken, since a non-boring
constraint will get chosen over a boring one.

To make the diagnostic output less fragile, this commit
adds a `ConstraintCategory::Usage` variant. We use this variant
for the temporary assignments created for each field of
an aggregate we are constructing.

Using this new variant, we can emit a message mentioning
"this usage", emphasizing the fact that the error message
is related to the specific use site (in the struct expression).

This is preparation for additional work on improving NLL error messages
(see rust-lang#57374)

…trait-selection, r=Mark-Simulacrum

cleanup(rustc_trait_selection): remove vestigial code from rustc_on_unimplemented

This isn't allowed by the validator, and seems to be unused.
When it was added in ed10a3f,
it was used on `Sized`, and that usage is gone.

Const Deref

Implements `const Deref`/`const DerefMut` for `&mut T`, `&T`, `Cow<'_, B>` and `ManuallyDrop<T>`

Move object safety suggestions to the end of the error

…nkov

Improve error message for type mismatch in generator arguments

Fixes rust-lang#88653. The code example given there is invalid because the `Generator` trait (unlike the `Fn` traits) does not take the generator arguments in tupled-up form (because there can only be one argument, from my understanding). Hence, the type error in the example in rust-lang#88653 is correct, because the given generator takes a `bool` argument, whereas the function's return type talks about a generator with a `(bool,)` argument.

The error message is both confusing and wrong, though: It is wrong because it displays the wrong "expected signature", and it is confusing because both the "expected" and "found" notes point at the same span. With my changes, I get the following, more helpful output:
```
error[E0631]: type mismatch in generator arguments
 --> test.rs:5:22
  |
5 | fn foo(bar: bool) -> impl Generator<(bool,)> {
  |                      ^^^^^^^^^^^^^^^^^^^^^^^ expected signature of `fn((bool,)) -> _`
6 |     |bar| {
  |     ----- found signature of `fn(bool) -> _`
```

Document the closure arguments for `reduce`.

See issue rust-lang#88927.

Add rustdoc version into the help popup

After a discussion with a rustdoc user about a specific behaviour, we realized we were not talking about the same version. To add on top of it, it was actually not that simple to find out the version since it was hosted documentation.

So to simplify things, I added the version into the help popup:

![Screenshot from 2021-09-16 10-45-52](https://user-images.githubusercontent.com/3050060/133581128-b93b460a-e1cb-4a31-9f2f-97c7a916cfcc.png)

Does the version format looks or would you prefer that I add more information? We can also add the commit hash, commit date, host and release.

cc `@rust-lang/rustdoc`
r? `@jyn514`

…ocs, r=Mark-Simulacrum

Clean up and add doc comments for CStr

CC rust-lang#51430

…call, r=ecstatic-morse

Allow calling `get_body_with_borrowck_facts` without `-Z polonius`

For my [static analysis tool](https://github.com/willcrichton/flowistry), I need to access the set of outlives-constraints. Recently, rust-lang#86977 merged a way to access these facts via Polonius. However, the merged implementation requires `-Z polonius` to be provided to use this feature. This uses Polonius for borrow checking on the entire crate, which as described [here](https://rust-lang.zulipchat.com/#narrow/stream/186049-t-compiler.2Fwg-polonius/topic/Polonius.20performance.20in.20a.20rustc.20plugin/near/251301631), is very slow.

This PR allows `get_body_with_borrowck_facts` to be called without `-Z polonius`. This is essential for my tool to run in a sensible length of time. This is a temporary patch as the Polonius-related APIs develop -- I can update my code as future changes happen.

Additionally, this PR also makes public two APIs that were previously public but then became private after `rustc_mir` got broken up: `rustc_mir_dataflow::framework::graphviz` and `rustc_mir_transform::MirPass`. I need both of these for my analysis tool. (I can break this change into a separate PR if necessary.)

Update clobber_abi list to include k[1-7] regs

Update the backtrace crate

rust-lang/backtrace-rs#437 fixed backtraces in
OpenBSD -> update it here as well so OpenBSD Rust code can produce
proper backtraces.