per pnkfelix's suggestion

suggested by arielb1

as suggested by arielb1

This includes the additional case suggested by arielb1.

It's just not useful. It also makes it hard to have tests that probe
internal state, since the interning number is very sensitive.

Dumping the number in the case of gensym is not ideal but will do for
now.

It's inefficient, and the substitution there doesn't account for the
extra regions used by NLL inference, so it's a bad thing to encourage.

As it happens all callers already know if they have a closure or not,
from what I can tell.

The overall format is now easier to read. Also, There is now graphviz
output, as well as a `#[rustc_regions]` annotation that dumps internal
state.

Rename C-like enum to Field-less enum

There is no need to reference the C programming language to explain this concept.

compiletest: account for `ui` reference files when deciding to skip

The stamp files for compiletest were ignoring `.stderr` and `.stdout` files. This was driving me crazy.

r? @alexcrichton

Stabilize abi_sysv64

Closes #36167, stabilizing the use of the "sysv64" ABI on x64 platforms where it is not the default ABI.

FCP on this is complete in the tracking issue.

rustc_mir: promote references of statics from other statics.

Fixes #46522 by also allowing `STATIC_REF` in MIR const-qualification, not just AST rvalue promotion.

Display `\t` in diagnostics code as four spaces

Follow up to #44386 using the unicode variable width machinery from #45711 to replace tabs in the source code when displaying a diagnostic error with four spaces (instead of only one), while properly accounting for this when calculating underlines.

Partly addresses #44618.

MIR borrowck: implement union-and-array-compatible semantics

Fixes #44831.
Fixes #44834.
Fixes #45537.
Fixes #45696 (by implementing DerefPure semantics, which is what we want going forward).

r? @nikomatsakis

Rollup of 7 pull requests

- Successful merges: #46136, #46378, #46431, #46483, #46495, #46502, #46512
- Failed merges:

Give compile_error macro examples

I cannot get Rust to build at all with it complaining about GCC not being a valid C compiler or something, so letting TravisCI be my tester...

Fixes #46171

Improve search style

Fixes #46494.

r? @QuietMisdreavus

Update old link

The CONTRIBUTING.md page currently links to an old wiki page in rust-lang/rust-wiki-backup. There is a more up-to-date page in-tree so I changed the link to point there so new contributors can find it more easily.

Document behavior of `ptr::swap` with overlapping regions of memory.

Fixes https://github.com/rust-lang/rust/issues/44479.

Mention the name of ? in Result's docs

Fixes #42725

or at least, this is the best we can really do. #35946 is tracking
better errors already, so that should cover the other part of it.

Fix use of rand in liballoc benches

Clarify what `-D warnings` or `-F warnings` does

They set all lints currently on the warning level to `deny` or `forbid`,
respectively.