structured suggestion for renamed-and-removed-lints

![lint_renamed](https://user-images.githubusercontent.com/1076988/42730470-f74688dc-87a9-11e8-8dfd-b3e1d70b0af8.png)

r? @estebank

Clarify how the quote macro is loaded

@QuietMisdreavus needed to figure this out for writing a testcase, this should be better documented.

r? @jseyfried

Update lint plugin sample code.

The sample code is out of sync with latest test code and broken.
I just copied missing feature gates.

tidy: add a new test for external dependencies

ensure all packages in Cargo.lock will be vendored, and fail if the
source packages isn't whitelisted.

the purpose is to avoid such kind of issues:
- #52029 Rustfmt isn't vendored correctly
- #42719 building beta with vendor=true fail due to network dependencies

as Rust comes with several external dependencies (clippy, miri, rustfmt, rls), it is important to have a way to catch some errors in the update of this submodules.

The new check in tidy quickly reads `Cargo.lock` to search for the `source` of all packages. This attribute is present when the package comes from external source (like `crates.io-index` or some `git` repository). Some sources are whitelisted (like `crates.io-index`) as the crates are vendored.

`Cargo.lock` extract with several cases (git, crates.io, and local).
```
[[package]]
name = "rustfmt-nightly"
version = "0.8.2"
source = "git+https://github.com/rust-lang-nursery/rustfmt?rev=5e5992517d3591e2708d4ca6b155dfcbdf3344b9#5e5992517d3591e2708d4ca6b155dfcbdf3344b9"
dependencies = [
...
]

[[package]]
name = "same-file"
version = "1.0.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
...
]

[[package]]
name = "rustdoc-themes"
version = "0.1.0"
```

r? @alexcrichton

CTFE: use binary_op to compare integer with match disriminant

This is needed to unblock https://github.com/solson/miri/pull/401: There is code in the Windows initialization functions that uses `match` to test whether a pointer is NULL.

I will add a testcase in miri; I was not sure where to add a testcase in Rust itself.

r? @oli-obk

resolve: Functions introducing procedural macros reserve a slot in the macro namespace as well

Similarly to https://github.com/rust-lang/rust/pull/52234, this gives us symmetry between internal and external views of a crate, but in this case it's always an error to call a procedural macro in the same crate in which it's defined.

Closes https://github.com/rust-lang/rust/issues/52225

Disable LlvmTools packaging with external LLVM

Fixes: #52102

Document rounding down in std::time::Durations's subsec_millis etc.

Now also the documentations of `subsec_millis`, `subsec_micros`, `as_millis` and `as_micros` make clear that the fractional nanosecond component is rounded down to whole units.

Fixed #52263

Fix link to RFC 1510

None

ensure all packages in Cargo.lock will be vendored, and fail if the
source packages isn't whitelisted.

Remove `ty_to_def_id`

fixes https://github.com/rust-lang/rust/issues/52341

The uses were mostly convenience and generally "too powerful" (would also have worked for types that weren't interesting at the use site)

r? @EddyB

rustdoc: don't panic when the cross-re-export handler sees a proc-macro

When i moved the macro cross-re-export inlining code into `clean::inline`, i thought that if a macro had a `Def` that said it was a bang macro, it wouldn't be a proc macro. I thought wrong. Turns out, the `quote!()` in `libproc_macro` is actually a proc-macro, and when the `quote!()` macro is re-exported, this proc-macro is accessed in its place. This causes any `proc_macro::*` glob re-export to pull in this proc-macro, causing the assertion i added to fire, leading to an ICE. This replaces that with an Option that ignores proc-macros for the time being.

Fixes https://github.com/rust-lang/rust/issues/52129

Fixes: #52102

Do not attempt to recompile codegen backend(s) with --keep-stage

Previously we'd attempt to recompile them and that would fail since
we've essentially not built the entire compiler yet, or we're faking
that fact. This commit should make us ignore the codegen backend build
as well.

Unlike the other compile steps, there is no CodegenBackendLink step that
we run here, because that is done later as a part of assembling the
final compiler and as an explicit function call.

r? @alexcrichton

I think this may fix or at least assist with #52174.

cc @RalfJung @tinco -- if you can test this patch locally that'd be
amazing; I don't want to recompile for the next couple hours to test it
locally. I don't think it can make the situation worse, and in fact, if
I've interpreted the cause of the failure correctly then this will fix
your problem.

Reach the body of functions returning `impl Trait` but don't treat it as public

fixes #52128

r? @pnkfelix

cc @EddyB

Update clippy and rls

r? @Manishearth

cc @kennytm @nrc

Removed the promotable field from CheckCrateVisitor...

and replaced it with the custom enum Promotability.

r? @oli-obk

Removed the promotable field from CheckCrateVisitor and replaced it with the structs Promotable and NotPromotable.

rustc: Tweak expansion of #[proc_macro] for 2018

The syntactical expansion of `#[proc_macro]` and related attributes currently
contains absolute paths which conflicts with a lint for the 2018 edition,
causing issues like #52214. This commit puts a band-aid on the issue by ensuring
that procedural macros can also migrate to the 2018 edition for now by tweaking
the expansion based on what features are activated. A more long-term solution
would probably tweak the edition hygiene of spans, but this should do the trick
for now.

Closes #52214

Revert #52212 (revert set opt-level = 3)

Setting -O3 causes LLVM to spuriously segfault at least on Linux. This PR reverts to -O2.

cc #52378

The best way to build a stage 2 rustc is now probably
  ./x.py build --stage 2 src/rustc # once
  ./x.py build --stage 2 --keep-stage 1 src/rustc

Remove most of `PartialEq` and `Hash` impls from AST and HIR structures

Continuation of https://github.com/rust-lang/rust/pull/49326, prerequisite for removing `PartialEq` for `Ident`.

This reverts commit 1731f0af, reversing
changes made to 0a8275f8.

Now also the documentations of `subsec_millis`, `subsec_micros`, `as_millis` and `as_micros` make clear that the fractional nanosecond component is rounded down to whole units.