When parsing `let x: i8 += 1` the compiler interprets `i8` as a trait
which makes it more complicated to do error recovery. More advanced
error recovery is not implemented in this commit.

…s between OS

… return types

Co-authored-by: lzutao <taolzu@gmail.com>

Fix rust-lang#70968, partially address rust-lang#66523.

GPRs only

Fixed sentence by removing a word.

…komatsakis

Expand "recursive opaque type" diagnostic

Fix rust-lang#70968, partially address rust-lang#66523.

… r=matthewjasper

Specialization is unsound

As discussed in rust-lang#31844 (comment), it might be a good idea to warn users of specialization that the feature they are using is unsound.

I also expanded the "incomplete feature" warning to link the user to the tracking issue.

Improve diagnostics for `let x += 1`

Fixes(?) rust-lang#66736

The code responsible for the `E0404` errors is [here](https://github.com/rust-lang/rust/blob/master/src/librustc_parse/parser/ty.rs#L399-L424) which I don't think can be easily modified to prevent emitting an error in one specific case. Because of this I couldn't get rid of `E0404` and instead added `E0067` along with a help message which will fix the problem.

r? @estebank

…akis

add raw_ref macros

In rust-lang#64490, various people were in favor of exposing `&raw` as a macro first before making the actual syntax stable. So this PR (unstably) introduces those macros.

I'll create the tracking issue if we're okay moving forward with this.

…ing-drop, r=matthewjasper,nikomatsakis

Report error when casting an C-like enum implementing Drop

Following approach described in rust-lang#35941

…, 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

Fixes 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.

…llaumeGomez

Only highlight doc search results via mouseover if mouse has moved

## What happens

- Go to https://doc.rust-lang.org/stable/std/index.html
- Put your mouse cursor somewhere in the middle where search results will appear and then don't move the mouse
- Press 's' to focus the search box
- Type a query that brings up enough search results to go under where your mouse cursor is
- Press the down arrow
- The search result that is one below where your mouse cursor is will be highlighted.

## What I expected

When not currently using the mouse, I expect doing a search and then pressing the down arrow to always highlight the first search result immediately below the search box.

## The fix

This feels a bit hacky to me; I'm open to other solutions. This introduces a global JS var that keeps track of whether the person searching has moved their mouse after doing a search or not, and only uses the mouse position to highlight search results if the person HAS moved the mouse AFTER doing a search.

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

Add asm!() support for hexagon

…enkov

Add E0763

… r=petrochenkov

Disallow loading crates with non-ascii identifier name.

This turns off external crate loading with non-ascii identifier names.

cc rust-lang#55467.

…, r=kinnison

Clean up some weird command strings

r? @kinnison

Fix typo in librustc_ast docs

Fixed sentence by removing a word.

Make novel structural match violations not a `bug`

Fixes (on master) rust-lang#73431.

Ideally, `CustomEq` would emit a strict subset of the structural match errors that are found by `search_for_structural_match_violation`, since it allows more cases due to value-based reasoning. However, const qualification is more conservative than `search_for_structural_match_violation` around associated constants, since qualification does not try to substitute type parameters.

In the long term, we should probably make const qualification work for generic associated constants, but I don't like extending its capabilities even further.

r? @pnkfelix