rustc: Prepare to enable ThinLTO by default

This commit *almost* enables ThinLTO and multiple codegen units in release mode by
default but is blocked on #46346 now before pulling the trigger.

Point to next token when it is in the expected line

r? @nikomatsakis

incr.comp.: Remove an unnecessary HIR access which enables hashing spans for type definitions.

r? @nikomatsakis

On type mismatch error highlight `&` when type matches

When the only difference between the two types in a type error is that
one is a reference to the other type (`T` vs `&T`) or both are
references differing only in their mutability (`&T` vs `&mut T`), don't
highlight the type (`T`).

Add case insensitive comparison, besides Levenstein for DYM

Closes #46332

Draft version. The idea is that Levenstein does not work for some cases when we have multiple equal weights for strings. I didn't understand the case with `if found != name => Some(found)` so it means that new code does not work correctly yet.

At least now I think that we might return all maximal weights from levenstein and think about next cases in priority order:

1) There is exact match -> None
2) There is exact match, but case insensitive -> Some(match)
3) There is some match from levenstein -> Some(matches.take_any)
4) There is no match -> None

@estebank WDYT?

Fix hygiene bug.

Fixes #42708.
r? @nrc

Fix invalid HTML escape

Fixes #46289.

r? @QuietMisdreavus

Bump to 1.24.0

* Update the in-tree version number
* Update the bootstrap compiler
* Remove `cfg(stage0)` annotations
* Update crate dependencies
* Update Cargo itself

Use suggestions instead of notes ref mismatches

On type mismatch errors, use a suggestion when encountering minimal
differences in type differences due to refs, instead of a note.

Generic Associated Types Parsing & Name Resolution

Hi!
This PR adds parsing for generic associated types! 🎉 🎉 🎉

Tracking Issue: #44265

## Notes For Reviewers
* [x] I still need to add the stdout and stderr files to my ui tests. It takes me a *long* time to compile the compiler locally, so I'm going to add this as soon as possible in the next day or so.
* [ ] My current ui tests aren't very good or very thorough. I'm reusing the `parse_generics` and `parse_where_clause` methods from elsewhere in the parser, so my changes work without being particularly complex. I'm not sure if I should duplicate all of the generics test cases for generic associated types. It might actually be appropriate to duplicate everything here, since we don't want to rely on an implementation detail in case it changes in the future. If you think so too, I'll adapt all of the generics test cases into the generic associated types test cases.
* [ ] There is still more work required to make the run-pass tests pass here. In particular, we need to make the following errors disappear:
```
error[E0110]: lifetime parameters are not allowed on this type
  --> ./src/test/run-pass/rfc1598-generic-associated-types/streaming_iterator.rs:23:41
   |
23 |     bar: <T as StreamingIterator>::Item<'static>,
   |                                         ^^^^^^^ lifetime parameter not allowed on this type
```
```
error[E0261]: use of undeclared lifetime name `'a`
  --> ./src/test/run-pass/rfc1598-generic-associated-types/iterable.rs:15:47
   |
15 |     type Iter<'a>: Iterator<Item = Self::Item<'a>>;
   |                                               ^^ undeclared lifetime
```
There is a FIXME comment in streaming_iterator. If you uncomment that line, you get the following:
```
error: expected one of `!`, `+`, `,`, `::`, or `>`, found `=`
  --> ./src/test/run-pass/rfc1598-generic-associated-types/streaming_iterator.rs:29:45
   |
29 | fn foo<T: for<'a> StreamingIterator<Item<'a>=&'a [i32]>>(iter: T) { /* ... */ }
   |                                             ^ expected one of `!`, `+`, `,`, `::`, or `>` here
```

r? @nikomatsakis

Rollup of 13 pull requests

- Successful merges: #45880, #46280, #46373, #46376, #46385, #46386, #46387, #46392, #46400, #46401, #46405, #46412, #46421
- Failed merges:

MIR: change "lvalue" terminology to "place".

As pointed out elsewhere, "lvalue" vs "rvalue" is a misleading/obscure distinction and several other choices have been proposed, the one I prefer being "place" vs "value".

This PR only touches the "lvalue" side, and only in MIR-related code, as it's already a lot and could rot.

On type mismatch errors, use a suggestion when encountering minimal
differences in type differences due to refs, instead of a note.

build_helper: destination file can't be up to date when not exists

Function "up_to_date" return incorrect result if mtime for all fetched sources is set to epoch time. Add existence check to function.

This fix required for a [Guix](https://www.gnu.org/software/guix/) package because a Nix builder set mtime of all sources to epoch time.

Hide private trait type params and show hidden items with document-private

As discussed in #46380, this PR removes the `strip-hidden` pass from `--document-private-items` which allows showing `#[doc(hidden)]` with rustdoc.

The second commit removes the trait implementation from the docs if the trait's parameter is private.

rustc: Filter out bogus extern crate warnings

Rustdoc has for some time now used the "everybody loops" pass in the compiler to
avoid typechecking and otherwise avoid looking at implementation details.
In #46115 the placement of this pass was pushed back in the compiler to after
macro expansion to ensure that it works with macro-expanded code as well. This
in turn caused the regression in #46271.

The bug here was that the resolver was producing `def_id` instances for
"possibly unused extern crates" which would then later get processed during
typeck to actually issue lint warnings. The problem was that *after* resolution
these `def_id` nodes were actually removed from the AST by the "everybody loops"
pass. This later, when we tried to take a look at `def_id`, caused the compiler
to panic.

The fix applied here is a bit of a heavy hammer which is to just, in this one
case, ignore the `extern crate` lints if the `def_id` looks "bogus" in any way
(basically if it looks like the node was removed after resolution). The real
underlying bug here is probably that the "everybody loops" AST pass is being
stressed to much beyond what it was originally intended to do, but this should
at least fix the ICE for now...

Closes #46271

wasm: Update LLVM to fix a test

This commit updates LLVM with some tweaks to the integer <-> floating point
conversion instructions to ensure that `as` in Rust doesn't trap.

Closes #46298

incr.comp.: Make traits::VTable encodable and decodable.

Make vtables encodable so we can cache the `trans_fulfill_obligation` query at some point.

r? @EddyB

Invert colors in important traits tooltip

Part of #46352.

r? @QuietMisdreavus

Fix rustdoc item summaries that are headers

Rustoc item summaries that are headers were not displayed at all because
they started with whitespace.

This PR fixes this and now removes the whitespace and then displays the
block.

I'm not sure if the rustdoc test is written correctly, if there's anything to improve, just let me know. :)

This fixes #46377.

This is how it looks when rendered out now:
![Rendered](https://i.imgur.com/7u8jUAM.png)

Remove librustdoc dependency on env_logger

We want librustdoc to pickup the env_logger dependency from
the sysroot. This ensures that the same copy of env_logger is used
for both internal crates (e.g. librustc_driver, libsyntax) and
librustdoc

Closes #46383

rustbuild: Fix a typo with the Cargo book

The usage of `Path::new` prevented out-of-tree builds (like the bots do) from
working by accident!

Closes #46195

Update Cargo to Wed Nov 29 15:19:05 2017 +0000

https://github.com/rust-lang/cargo/commit/5bb478a518bcf75537409e8b71f6b7cc4af362df

Pick up `workspace.default-members` support: https://github.com/rust-lang/cargo/pull/4743

NetBSD: add sysctl backend for std::env::current_exe

Use the CTL_KERN.KERN_PROC_ARGS.-1.KERN_PROC_PATHNAME sysctl in
preference over the /proc/curproc/exe symlink.

Additionally, perform more validation of aformentioned symlink.
Particularly on pre-8.x NetBSD this symlink will point to '/' when
accurate information is unavailable.

rustc_llvm: remove stale references

...that were removed in 77c3bfa7.

r? @alexcrichton

make coercions to `!` in unreachable code a hard error

This was added to cover up a lazy extra semicolon in #35849, but does
not actually make sense. This is removed as a part of the stabilization
of `never_type`.

incr.comp.: Load cached diagnostics lazily and allow more things in the cache.

This PR implements makes two changes:
1. Diagnostics are loaded lazily from the incr. comp. cache now. This turned out to be necessary for correctness because diagnostics contain `Span` values and deserializing those requires that the source file they point to is still around in the current compilation session. Obviously this isn't always the case. Loading them lazily allows for never touching diagnostics that are not valid anymore.
2. The compiler can now deal with there being no cache entry for a given query invocation. Before, all query results of a cacheable query were always expected to be present in the cache. Now, the compiler can fall back to re-computing the result if there is no cache entry found. This allows for caching things that we cannot force from dep-node (like the `symbol_name` query). In such a case we'll just have a "best effort" caching strategy.

~~This PR is based on https://github.com/rust-lang/rust/pull/46301 (=first 2 commits), so please don't merge until that has landed. The rest of the commits are ready for review though.~~

r? @nikomatsakis

MIR-borrowck: immutable unique closure upvars can be mutated

Fixes #46023 and #46160 (see [this comment](https://github.com/rust-lang/rust/pull/46236#issuecomment-347204874)).

incr.comp.: Load diagnostics from previous session lazily and clean up on-disk-cache persistence code.

The previous method ran into problems because ICH would treat Spans
as (file,line,col) but the cache contained byte offsets and its
possible for the latter to change while the former stayed stable.

Function "up_to_date" return incorrect result if mtime for all fetched
sources is set to epoch time. Add existence check to function.

disable jemalloc on executables for ios targets

This is a (temporary ?) workaround for issue #45262