This reverts commit 648caced.

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Add support for Arm64 Catalyst on ARM Macs

This is an iteration on https://github.com/rust-lang/rust/pull/63467 which was merged a while ago. In the aforementioned PR, I added support for the `X86_64-apple-ios-macabi` target triple, which is Catalyst, iOS apps running on macOS.

Very soon, Apple will launch ARM64 based Macs which will introduce `aarch64_apple_darwin.rs`, macOS apps using the Darwin ABI running on ARM. This PR adds support for Catalyst apps on ARM Macs: iOS apps compiled for the darwin ABI.

I don't have access to a Apple Developer Transition Kit (DTK), so I can't really test if the generated binaries work correctly. I'm vaguely hopeful that somebody with access to a DTK could give this a spin.

Store HIR ForeignItem in a side table

In a similar fashion to Item, ImplItem and TraitItem.

rustc_parse: restore public visibility on parse_attribute

Make `parse_attribute` public as rustfmt is a downstream consumer. Refs https://github.com/rust-lang/rust/pull/78782#discussion_r530658904

r? `@petrochenkov`

Skip most of `create_substs_for_ast_path` if type is not generic

Generic Associated Types in Trait Paths - Ast part

The Ast part of https://github.com/rust-lang/rust/pull/78978

r? `@petrochenkov`

Co-authored-by: Nvarkor <github@varkor.com>

Cache pretty-print/retokenize result to avoid compile time blowup

Fixes #79242

If a `macro_rules!` recursively builds up a nested nonterminal
(passing it to a proc-macro at each step), we will end up repeatedly
pretty-printing/retokenizing the same nonterminals. Unfortunately, the
'probable equality' check we do has a non-trivial cost, which leads to a
blowup in compilation time.

As a workaround, we cache the result of the 'probable equality' check,
which eliminates the compilation time blowup for the linked issue. This
commit only touches a single file (other than adding tests), so it
should be easy to backport.

The proper solution is to remove the pretty-print/retokenize hack
entirely. However, this will almost certainly break a large number of
crates that were relying on hygiene bugs created by using the reparsed
`TokenStream`. As a result, we will definitely not want to backport
such a change.

Always print lints from plugins, if they're available

Currently you can get a list of lints and lint groups by running `rustc
-Whelp`. This prints an additional line at the end:
```
Compiler plugins can provide additional lints and lint groups. To see a listing of these, re-run `rustc -W help` with a crate filename.
```

Clippy is such a "compiler plugin", that provides additional lints.
Running `clippy-driver -Whelp` (`rustc` wrapper) still only prints the
rustc lints with the above message at the end. But when running
`clippy-driver -Whelp main.rs`, where `main.rs` is any rust file, it
also prints Clippy lints. I don't think this is a good approach from a
UX perspective: Why is a random file necessary to print a help message?

This PR changes this behavior: Whenever a compiler callback
registers lints, it is assumed that these lints come from a plugin and
are printed without having to specify a Rust source file.

Fixes rust-lang/rust-clippy#6122

cc `@Manishearth` `@ebroto` for the Clippy changes.

Normalize `<X as Y>::T` for rustdoc

- Only run for `QPath::Resolved` with `Some` self parameter (`<X as Y>::T`)
- Fall back to the previous behavior if the path can't be resolved

The first commit is a pure refactor and should probably be reviewed by `@GuillaumeGomez.` I recommend reviewing the second commit on its own.

Fixes https://github.com/rust-lang/rust/issues/77459.

r? `@EddyB`
cc `@danielhenrymantilla` , `@lcnr`

Rollup of 10 pull requests

Successful merges:

 - #77758 (suggest turbofish syntax for uninferred const arguments)
 - #79000 (Move lev_distance to rustc_ast, make non-generic)
 - #79362 (Lower patterns before using the bound variable)
 - #79365 (Upgrades the coverage map to Version 4)
 - #79402 (Fix typos)
 - #79412 (Clean up rustdoc tests by removing unnecessary features)
 - #79413 (Fix persisted doctests on Windows / when using workspaces)
 - #79420 (Fixes a word typo in librustdoc)
 - #79421 (Fix docs formatting for `thir::pattern::_match`)
 - #79428 (Fixup compiler docs)

Failed merges:

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

... and fix some fuzzy wording in the debug logging.

Fixup compiler docs

The sublist was being rendered as a code block because it was indented 4
spaces.

Fix docs formatting for `thir::pattern::_match`

They were being rendered all on one line.

Fixes a word typo in librustdoc

Fixes a word typo in librustdoc

Fix persisted doctests on Windows / when using workspaces

When using the unstable `--persist-doctests` option,
Windows path separators were not escaped properly. Also when running
the command in a workspace, crate files can overwrite each other.

Before: `src\lib_rs_1_0\rust_out`
After: `\crate_a_src_lib_rs_1_0\rust_out`, `\crate_b_src_lib_rs_1_0\rust_out`

Clean up rustdoc tests by removing unnecessary features

r? ``@jyn514``

Fix typos

Upgrades the coverage map to Version 4

Changes the coverage map injected into binaries compiled with
`-Zinstrument-coverage` to LLVM Coverage Mapping Format, Version 4 (from
Version 3). Note, binaries compiled with this version will require LLVM
tools from at least LLVM Version 11.

r? ``@wesleywiser``

Lower patterns before using the bound variable

So as to avoid having to lower patterns twice.

Move lev_distance to rustc_ast, make non-generic

rustc_ast currently has a few dependencies on rustc_lexer. Ideally, an AST
would not have any dependency its lexer, for minimizing
design-time dependencies. Breaking this dependency would also have practical
benefits, since modifying rustc_lexer would not trigger a rebuild of rustc_ast.

This commit does not remove the rustc_ast --> rustc_lexer dependency,
but it does remove one of the sources of this dependency, which is the
code that handles fuzzy matching between symbol names for making suggestions
in diagnostics. Since that code depends only on Symbol, it is easy to move
it to rustc_span. It might even be best to move it to a separate crate,
since other tools such as Cargo use the same algorithm, and have simply
contain a duplicate of the code.

This changes the signature of find_best_match_for_name so that it is no
longer generic over its input. I checked the optimized binaries, and this
function was duplicated for nearly every call site, because most call sites
used short-lived iterator chains, generic over Map and such. But there's
no good reason for a function like this to be generic, since all it does
is immediately convert the generic input (the Iterator impl) to a concrete
Vec<Symbol>. This has all of the costs of generics (duplicated method bodies)
with no benefit.

Changing find_best_match_for_name to be non-generic removed about 10KB of
code from the optimized binary. I know it's a drop in the bucket, but we have
to start reducing binary size, and beginning to tame over-use of generics
is part of that.

suggest turbofish syntax for uninferred const arguments

When not providing a const generic value, and it can not be inferred, the following suggestion is suggested:
![image](https://user-images.githubusercontent.com/39732259/95616180-af127b80-0a69-11eb-8877-551c815f9627.png)

Resolves #76737

r? ``@varkor``

Resolve inference variables before trying to remove overloaded indexing

Fixes #79152

This code was already set up to handle indexing an array. However, it
appears that we never end up with an inference variable for the slice
case, so the missing call to `resolve_vars_if_possible` had no effect
until now.

Mirror centos vault to S3

Fixes #79152

This code was already set up to handle indexing an array. However, it
appears that we never end up with an inference variable for the slice
case, so the missing call to `resolve_vars_if_possible` had no effect
until now.