Namely closures and `async` blocks. We have to make a few modifications
to closures to make them compile.

In rust-lang#72936 (comment),
it was determined that some unusual code could cause rustc to overflow
when evaluating a predicate of the form `T: AutoTrait`. Even if this is
a bug, it will still be possible to cause overflow through writing
explicit impls of auto traits, just like any other type of impl.

In rustdoc, this overflow can happen simply as a result of defining
certain types, since we will automatically generate and evaluate
auto-trait predicates when generating documentation.

For now, we just ignore overflow during selection if it occurs in
rustdoc. We should probably come up with a better way to handle this -
e.g. rendering some kind of error in the generated documentation.
However, this is a very unusual corner case, and this PR is sufficient
to unblock landing a Chalk update in PR rust-lang#72936

This adds additional hacks to `librustc_trait_selection`. The
auto-trait-finding code should probably be completely rewritten, but I
think this is good enough for the time being.

This should run much faster.

There are also some drive-by cleanups here to try to simplify things.
Also, the paths for in-tree crates are now displayed as relative
in `x.py test -h -v`.

…s between OS

- Suggest borrowing expression if it would allow cast to work.
- Suggest using `<Type>::from(<expr>)` when appropriate.
- Minor tweak to `;` typo suggestion.

Partily address rust-lang#47136.

… return types

…epmaster

Add tests for 'impl Default for [T; N]'

Related: rust-lang#71690.
This pull request adds two tests:
- Even it T::default() panics, no leaks occur.
- [T; 0] is Default even if T is not.

I believe at some moment `Default` impl for arrays will be rewritten to use const generics instead of macros, and these tests will help to prevent behavior changes.

…, r=nikomatsakis

Further tweak lifetime errors involving `dyn Trait` and `impl Trait` in return position

* Suggest substituting `'static` lifetime in impl/dyn `Trait + 'static` instead of `Trait + 'static + '_`
* When `'static` is explicit, also suggest constraining argument with it
* Reduce verbosity of suggestion message and mention lifetime in label
* Tweak output for overlapping required/captured spans
* Give these errors an error code

Follow up to rust-lang#72543.

r? @nikomatsakis

…ies, r=shepmaster

Complete the std::time documentation to warn about the inconsistencies between OS

Fix for rust-lang#48980.

I put the new documentation in `src/libstd/time.rs` at the module-level because it affects all types, even the one that are not directly system dependents if they are used with affected types, but there may be a better place for it.

Fix link error with #[thread_local] introduced by rust-lang#71192

r? @oli-obk

…op, r=pnkfelix

Preserve `Expr`s that have `DefId`s in `ReplaceBodyWithLoop`

This PR fixes rust-lang#71820 as well as the last part of rust-lang#71104 by preserving expressions that are assigned their own `DefId`s (closures and `async` blocks) when passing them to `rustdoc`. This avoids having a `DefId` without a corresponding `HirId`.

The first commit in this PR makes `-Zunpretty=everybody_loops` actually work again, and the subsequent two are miscellaneous cleanup. They should probably get merged regardless of what we end up doing here.

Sample input:
```rust
fn foo() -> Box<i32> {
    let x = |a: i64| {
        const FOO: i64 = 1;
    };

    let a = 4;
    Box::new(a)
}
```

Sample output:
```rust
fn foo() -> Box<i32> {
    || -> !
        {
            const FOO: i64 = 1;
            loop  { }
        };
    loop  { }
}
```

r? @ghost

Ensure std benchmarks get tested.

This ensures that the std benchmarks don't break in the future. Currently they aren't compiled or tested on CI, so they can easily bitrot.  Testing a benchmark runs it with one iteration. Adding these should only add a few seconds to CI.

Closes rust-lang#54176
Closes rust-lang#61913

…stebank

Ignore overflow when finding auto-trait impls in Rustdoc

In rust-lang#72936 (comment),
it was determined that some unusual code could cause rustc to overflow
when evaluating a predicate of the form `T: AutoTrait`. Even if this is
a bug, it will still be possible to cause overflow through writing
explicit impls of auto traits, just like any other type of impl.

In rustdoc, this overflow can happen simply as a result of defining
certain types, since we will automatically generate and evaluate
auto-trait predicates when generating documentation.

For now, we just ignore overflow during selection if it occurs in
rustdoc. We should probably come up with a better way to handle this -
e.g. rendering some kind of error in the generated documentation.
However, this is a very unusual corner case, and this PR is sufficient
to unblock landing a Chalk update in PR rust-lang#72936

This adds additional hacks to `librustc_trait_selection`. The
auto-trait-finding code should probably be completely rewritten, but I
think this is good enough for the time being.

…mulacrum

Speed up bootstrap a little.

The bootstrap script was calling `cargo metadata` 3 times (or 6 with `-v`). This is a very expensive operation, and this attempts to avoid the extra calls. On my system, a simple command like `./x.py test -h -v` goes from about 3 seconds to 0.4.

An overview of the changes:

- Call `cargo metadata` only once with `--no-deps`. Optional dependencies are filtered in `in_tree_crates` (handling `profiler_builtins` and `rustc_codegen_llvm` which are driven by the config).
- Remove a duplicate call to `metadata::build` when using `-v`. I'm not sure why it was there, it looks like a mistake or vestigial from previous behavior.
- Remove check for `_shim`, I believe all the `_shim` crates are now gone.
- Remove check for `rustc_` and `*san` for `test::Crate::should_run`, these are no longer dependencies in the `test` tree.
- Use relative paths in `./x.py test -h -v` output.
- Some code cleanup (remove unnecessary `find_compiler_crates`, etc.).
- Show suite paths (`src/test/ui/...`) in `./x.py test -h -v` output.
- Some doc comments.

Use `LocalDefId` for import IDs in trait map

cc rust-lang#73291 (comment)

…dtwco

Tweak "non-primitive cast" error

- Suggest borrowing expression if it would allow cast to work.
- Suggest using `<Type>::from(<expr>)` when appropriate.
- Minor tweak to `;` typo suggestion.

Partily address rust-lang#47136.

…tions, r=kinnison

Re-order correctly the sections in the sidebar

Before that, "trait implementations" and "implementors" titles in the sidebar were before "methods" for example. Which wasn't logical considering that the two sections come after in the "content".

r? @kinnison

Use track caller for bug! macro

…num-cpus, r=Mark-Simulacrum

Add more info to `x.py build --help` on default value for `-j JOBS`.

…chievink

Fix typo in docs of std::mem