alway -> always

Rollup of 7 pull requests

Successful merges:

 - #90905 (Add empty impl blocks if they have documentation)
 - #97683 (Fail gracefully when encountering an HRTB in APIT. )
 - #97721 (Do `suggest_await_before_try` with infer variables in self, and clean up binders)
 - #97752 (typo: `-Zcodegen-backend=llvm -Cpasses=list` should work now)
 - #97759 (Suggest adding `{}` for `'label: non_block_expr`)
 - #97764 (use strict provenance APIs)
 - #97765 (Restore a test that was intended to test `as` cast to ptr)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Restore a test that was intended to test `as` cast to ptr

This test was changed in https://github.com/rust-lang/rust/pull/61864, but the original bug https://github.com/rust-lang/rust/issues/46365 was about casts so I doubt the changed test still even tests what this was intended to test. Let's restore the original test.

use strict provenance APIs

The stdlib was adjusted to avoid bare int2ptr casts, but recently some casts of that sort have sneaked back in. Let's fix that. :)

Suggest adding `{}` for `'label: non_block_expr`

Adds suggestions like this:
```text
help: consider enclosing expression in a block
  |
3 |     'l {0};
  |        + +
```

inspired by https://github.com/rust-lang/rust/issues/48594#issuecomment-1146744400

r? ``@compiler-errors``

typo: `-Zcodegen-backend=llvm -Cpasses=list` should work now

r? ```@bjorn3```

Do `suggest_await_before_try` with infer variables in self, and clean up binders

Fixes #97704

Also cleans up binders in this fn, since everything is a `Poly*` and we really shouldn't have stray escaping late-bound regions everywhere. That's why the function changed so much. This isn't necessary, so I can revert if necessary.

Fail gracefully when encountering an HRTB in APIT.

Fixes https://github.com/rust-lang/rust/issues/96954

~The first commit will be merged as part of https://github.com/rust-lang/rust/pull/97415~

Add empty impl blocks if they have documentation

Fixes https://github.com/rust-lang/rust/issues/90866.

The update for the test script is needed to count the number of impl blocks we have with only the struct. To be noted that with https://github.com/rust-lang/rust/pull/89676 merged, it wouldn't be needed (I don't know what is the status of it btw. cc ```@Mark-Simulacrum).```

It looks like this:

![Screenshot from 2021-11-14 16-51-28](https://user-images.githubusercontent.com/3050060/141689100-e57123c0-bf50-4c42-adf5-d991e169a0e4.png)

cc ```@jyn514```
r? ```@camelid```

[compiletest] Ignore known paths when abbreviating output

To prevent out of memory conditions, compiletest limits the amount of output a test can generate, abbreviating it if the test emits more than a threshold. While the behavior is desirable, it also causes some issues (like #96229, #94322 and #92211).

The latest one happened recently, when the `src/test/ui/numeric/numeric-cast.rs` test started to fail on systems where the path of the rust-lang/rust checkout is too long. This includes my own development machine and [LLVM's CI](https://github.com/rust-lang/rust/issues/96362#issuecomment-1108609893). Rust's CI uses a pretty short directory name for the checkout, which hides these sort of problems until someone runs the test suite on their own computer.

When developing the fix I tried to find the most targeted fix that would prevent this class of failures from happening in the future, deferring the decision on if/how to redesign abbreviation to a later date. The solution I came up with was to ignore known base paths when calculating whether the output exceeds the abbreviation threshold, which removes this kind of nondeterminism.

This PR is best reviewed commit-by-commit.

implement ptr.addr() via transmute

As per the discussion in https://github.com/rust-lang/unsafe-code-guidelines/issues/286, the semantics for ptr-to-int transmutes that we are going with for now is to make them strip provenance without exposing it. That's exactly what `ptr.addr()` does! So we can implement `ptr.addr()` via `transmute`. This also means that once https://github.com/rust-lang/rust/pull/97684 lands, Miri can distinguish `ptr.addr()` from `ptr.expose_addr()`, and the following code will correctly be called out as having UB (if permissive provenance mode is enabled, which will become the default once the [implementation is complete](https://github.com/rust-lang/miri/issues/2133)):

```rust
fn main() {
    let x: i32 = 3;
    let x_ptr = &x as *const i32;

    let x_usize: usize = x_ptr.addr();
    // Cast back an address that did *not* get exposed.
    let ptr = std::ptr::from_exposed_addr::<i32>(x_usize);
    assert_eq!(unsafe { *ptr }, 3); //~ ERROR Undefined Behavior: dereferencing pointer failed
}
```

This completes the Miri implementation of the new distinctions introduced by strict provenance. :)

Cc `@Gankra` -- for now I left in your `FIXME(strict_provenance_magic)` saying these should be intrinsics, but I do not necessarily agree that they should be. Or if we have an intrinsic, I think it should behave exactly like the `transmute` does, which makes one wonder why the intrinsic should be needed.

Co-authored-by: NMichael Goulet <michael@errs.io>

Remove Azure Pipelines configuration

This PR removes the remaining Azure Pipelines configuration, now that we fully removed all the resources on the Azure side of things.

The script wasn't referenced anywhere, and it's not useful anymore:
/opt/ghc is not present in new images, while /usr/share/dotnet is only
2.3 GB rather than 16 GB.

Replace `&Vec<_>`s with `&[_]`s

It's generally preferable to use `&[_]` since it's one less indirection and it can be created from types other that `Vec`.

I've left `&Vec` in some locals where it doesn't really matter, in cases where `TypeFoldable` is expected (`TypeFoldable: Clone` so slice can't implement it) and in cases where it's `&TypeAliasThatIsActiallyVec`. Nothing important, really, I was just a little annoyed by `visit_generic_param_vec` :D

r? `@compiler-errors`

riscv32imac-unknown-xous-elf: add target

This PR starts the process of upstreaming support for our operating system, thanks to a suggestion from `@yaahc` [on Twitter](https://twitter.com/yaahc_/status/1530558574706839567?s=20&t=Mgkn1LEYvGU6FEi5SpZRsA). We have maintained a fork of Rust and have made changes to improve support for our platform since Rust 1.51. Now we would like to upstream these changes.

Xous is a microkernel operating system designed to run on small systems. The kernel contains a wide range of userspace processes that provide common services such as console output, networking, and time access.

The kernel and its services are completely written in Rust using a custom build of libstd. This adds support for this target to upstream Rust so that we can drop support for our out-of-tree `target.json` file.

This first patch adds a Tier 3 target for Xous running on RISC-V. Future patches will add libstd support, but those patches require changes to `dlmalloc` and `compiler_builtins`.

> Tier 3 policy:
>
> A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)

I will be the target maintainer for this target on matters that pertain to the `xous` part of the triple. For matters pertaining to the `riscv32imac` part of the triple, there should be no difference from all other `riscv` targets. If there are issues, I will address issues regarding the target.

> Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.

This is a new OS, so I have taken the `riscv32imac-unknown-none-elf` target and changed the `os` section of the triple. This follows convention on targets such as `riscv32gc-unknown-linux-gnu` and `mipsel-unknown-linux-uclibc`. An argument could be made for omitting the `-elf` section of the triple, such as `riscv32imc-esp-espidf`, however I'm not certain what benefit that has.

> Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.

I feel that the target name does not introduce any ambiguity.

> Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.

The only unusual requirement for building the `compiler-builtins` crate is a standard RISC-V C compiler supported by `cc-rs`, and using this target does not require any additional software beyond what is shipped by `rustup`.

> The target must not introduce license incompatibilities.

All of the additional code will use Apache-2.0.

> Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0).

Agreed, and there is no problem here.

> The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.

The only new dependency will be the `xous` crate, which is licensed `MIT OR Apache-2.0`

> Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.

Linking is performed by `rust-lld`

> "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.

There are no terms. Xous is completely open. It runs on open hardware. We even provide the source to the CPU.

> Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.

This paragraph makes sense, but I don't think it's directed at me.

> This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements.

This paragraph also does not appear to be directed at me.

> Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.

So far we have:

 * Thread
 * Mutexex
 * Condvar
 * TcpStream
 * TcpListener
 * UdpSocket
 * DateTime
 * alloc

These will be merged as part of libstd in a future patch once I submit support for Xous in `dlmalloc` and `compiler-builtins`.

> The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary.

Testing is currently done on real hardware or in a Renode emulator. I can add documentation on how to do this in a future patch, and I would need instructions on where to add said documentation.

> Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.

Alright.

> Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.

Sounds good.

> Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.

This shouldn't affect any other targets, so this is understood.

> In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.

This shouldn't come up right away. `xous` is a new operating system, and most features are keyed off of `target(os = "xous")` rather than a given architecture.

Handle more cases in cfg_accessible

This PR tries to handle more cases in the cfg_accessible implementation by only emitting a "not sure" error only if we have partially resolved a path.

This PR also adds many tests for the "not sure" cases and for private items.

r? `@petrochenkov`

Add build metrics to rustbuild

This PR adds a new module of rustbuild, `ci_profiler`, whose job is to gather as much information as possible about the CI build as possible and store it in a JSON file uploaded to `ci-artifacts`. Right now for each step it collects:

* Type name and debug representation of the `Step` object.
* Duration of the step (excluding child steps).
* Systemwide CPU stats for the duration of the step (both single core and all cores).
* Which child steps were executed.

This is capable of replacing both the scripts to collect CPU stats and the `[TIMING]` lines in build logs (not yet removed, until we port our tooling to use the CI profiler). The format is also extensible to be able in the future to collect more information.

r? `@Mark-Simulacrum`

Rollup of 6 pull requests

Successful merges:

 - #97609 (Iterate over `maybe_unused_trait_imports` when checking dead trait imports)
 - #97688 (test const_copy to make sure bytewise pointer copies are working)
 - #97707 (Improve soundness of rustc_data_structures)
 - #97731 (Add regresion test for #87142)
 - #97735 (Don't generate "Impls on Foreign Types" for std)
 - #97737 (Fix pretty printing named bound regions under -Zverbose)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Fix pretty printing named bound regions under -Zverbose

Fixed regression introduced in #97023

r? `@compiler-errors`

cc `@cjgillot`

Don't generate "Impls on Foreign Types" for std

Hack: many traits and types in std are re-exported from core or alloc. In general, rustdoc is capable of recognizing these implementations as being on local types. However, in at least one case, rustdoc gets confused and labels an implementation as being on a foreign type. To make sure that confusion doesn't pass on to the reader, consider all implementations in std, core, and alloc to be on local types.

Demo: https://rustdoc.crud.net/jsha/no-foreign-std/std/clone/trait.Clone.html

Add regresion test for #87142

Closes #87142
r? `@compiler-errors`

Improve soundness of rustc_data_structures

Make it runnable in miri by adding some ignores and changing N in miri. Also fix a stacked borrows issue in sip128.

test const_copy to make sure bytewise pointer copies are working

This is non-trivial; for `swap_nonoverlapping`, this is [not working](https://github.com/rust-lang/rust/issues/83163#issuecomment-1145917372).

Iterate over `maybe_unused_trait_imports` when checking dead trait imports

Closes #96873
r? `@cjgillot`

Some questions, if you have time:

- Is there a way to shorten the `rustc_data_structures::fx::FxIndexSet` path in the query declaration? I wasn't sure where to put a `use`.
- Was returning by reference from the query the right choice here?
- How would I go about evaluating the importance of the `is_dummy()` call in `check_crate`? I don't see failing tests when I comment it out. Should I just try to determine whether dummy spans can ever be put into `maybe_unused_trait_imports`?
- Am I doing anything silly with the various ID types?
- Is that `let-else` with `unreachable!()` bad? (i.e is there a better idiom? Would `panic!("<explanation>")` be better?)
- If I want to evaluate the perf of using a `Vec` as mentioned in #96873, is the best way to use the CI or is it feasible locally?

Thanks :)

Call the OS function to set the main thread's name on program init

Normally, `Thread::spawn` takes care of setting the thread's name, if
one was provided, but since the main thread wasn't created by calling
`Thread::spawn`, we need to call that function in `std::rt::init`.

This is mainly useful for system tools like debuggers and profilers
which might show the thread name to a user. Prior to these changes, gdb
and WinDbg would show all thread names except the main thread's name to
a user. I've validated that this patch resolves the issue for both
debuggers.

Hack: many traits and types in std are re-exported from core or alloc. In
general, rustdoc is capable of recognizing these implementations as being
on local types. However, in at least one case, rustdoc gets confused and
labels an implementation as being on a foreign type. To make sure that
confusion doesn't pass on to the reader, consider all implementations in
std, core, and alloc to be on local types.