It was already filtered from other branches, but we only kept it in
nightly's default to ease the transition. Now that the separation of
rust-std/rustc-dev has reached the 1.40 release, it seems like a good
time for that transition to end.

* Make some run-pass or check-pass
* Use `#![allow(incomplete_features)]`
* Update FIXMEs now that some of the issues have been addressed
* Add regression tests

It was essentially unused, likely leftover from a previous refactoring
iteration.

…atsakis

Make GATs less ICE-prone.

After this PR simple lifetime-generic associated types can now be used in a compiling program. There are two big limitations:

* rust-lang#30472 has not been addressed in any way (see src/test/ui/generic-associated-types/iterable.rs)
* Using type- and const-generic associated types errors because bound types and constants aren't handled by trait solving.
    * The errors are technically non-fatal, but they happen in a [part of the compiler](https://github.com/rust-lang/rust/blob/4abb0ad2731e9ac6fd5d64d4cf15b7c82e4b5a81/src/librustc_typeck/lib.rs#L298) that fairly aggressively stops compiling on errors.

closes rust-lang#47206
closes rust-lang#49362
closes rust-lang#62521
closes rust-lang#63300
closes rust-lang#64755
closes rust-lang#67089

…ce, r=oli-obk

[mir-opt] Fix `Inline` pass to handle inlining into `box` expressions

r? @oli-obk

Before, the test case just ICE'd here:

https://github.com/rust-lang/rust/blob/a605441e049f0b6d5f7715b94b8ac4662fd7fcf6/src/librustc_mir/transform/inline.rs#L668

use _val to ignore parameter of any::type_name_of_val

mem::drop does the same thing too.

…k-Simulacrum

Remove rustc-dev from the default nightly components

It was already filtered from other branches, but we only kept it in
nightly's default to ease the transition. Now that the separation of
rust-std/rustc-dev has reached the 1.40 release, it seems like a good
time for that transition to end.

Closes rust-lang#67425.
r? @Mark-Simulacrum

…ntril

Drop petgraph dependency from bootstrap

It was essentially unused, likely leftover from a previous refactoring iteration. This should hopefully help reduce bootstrap build times a little, dropping petgraph, fixedbitset, and ordermap from the dependency set.

r? @alexcrichton

Document privacy of RangeInclusive fields

Fixes rust-lang#67371

use Result::map_or for bootstrap