Change-Id: Ib3a396e7334d209fe6c6ef425bbfc7b2ae471378

Change-Id: Ib3a396e7334d209fe6c6ef425bbfc7b2ae471378

This commit modifies the uninhabitedness checking so that the fields of
a non-exhaustive variant (which is not local) are ignored if they are
uninhabited. This is an improvement over the previous behaviour which
considered all non-local non-exhaustive variants useful because
unreachable patterns are now detected.

Signed-off-by: David Wood <[email protected]>

Add test for rejecting `trait A: B1 = B2;`.
Also test rejection of `trait A: = B;`.

Also elaborate on some feature gates in `active.rs`.

Change-Id: Ib3a396e7334d209fe6c6ef425bbfc7b2ae471378

The iterator is implemented using const generics. It implements the
traits `Iterator`, `DoubleEndedIterator`, `ExactSizeIterator`,
`FusedIterator` and `TrustedLen`. It also contains a public method
`new` to create it from an array.

`IntoIterator` was not implemented for arrays yet, as there are still
some open questions regarding backwards compatibility. This commit
only adds the iterator impl and does not yet offer a convenient way
to obtain that iterator.

Many tests are based on tests by Josh Stone <[email protected]>

This it to make sure traits are implemented for arrays with length 32
and below, while they are not implemented for >= 33.

…mple

…example

…=scottmcm

Add by-value iterator for arrays

This adds an iterator that can iterate over arrays by value, yielding all elements by value. However, **this PR does _not_ add a corresponding `IntoIterator` impl for arrays**. The `IntoIterator` impl needs some discussion about backwards-compatibility that should take place in a separate PR. With this patch, this code should work (but there is currently still a bug):

```rust
#![feature(array_value_iter)]
use std::array::IntoIter;

let arr = [1, 2, 3];
for x in IntoIter::new(arr) {
    println!("{}", x);
}
```

**TODO**:
- [x] Get initial feedback
- [x] Add tests
- [x] Figure out why stage1 produces weird bugs ([comment](rust-lang#62959 (comment)))
- [x] Add UI tests as mentioned [here](rust-lang#62959 (comment)) (will do that soon-ish)
- [x] Fix [this new bug](rust-lang#62959 (comment))

**Notes for reviewers**
- Is the use of `MaybeUninit` correct here? I think it has to be used due to the `Clone` impl which has to fill the dead array elements with something, but cannot fill it with a correct instance.
- Are the unit tests sufficient?

CC rust-lang#25725

…-E0576, r=matthewjasper,kinnison

Add long error explanation for E0576

Part of rust-lang#61137.

…k-Simulacrum

reorder config.toml.example options and add one missing option

r? @Mark-Simulacrum

…e-always-useful, r=varkor

ignore uninhabited non-exhaustive variant fields

Fixes rust-lang#65157.

This PR modifies the uninhabitedness checking so that the fields of
a non-exhaustive variant (which is not local) are ignored if they are
uninhabited. This is an improvement over the previous behaviour which
considered all non-local non-exhaustive variants useful because
unreachable patterns are now detected.

r? @arielb1
cc @varkor

Deprecated proc_macro doesn't trigger warning on build library

Fix rust-lang#65189

…r=davidtwco

Pre-expansion gate most of the things

This is a subset of rust-lang#64672. A crater run has already been done and this PR implements conclusions according to rust-lang#64672 (comment).

r? @davidtwco
cc @petrochenkov

Adjust the tracking issue for `untagged_unions`.

Makes rust-lang#55149 the new tracking issue for `untagged_unions`.
Closes rust-lang#32836 which is the old tracking issue.

r? @varkor

Changed APIT with explicit generic args span to specific arg spans

Fixes rust-lang#65642.

Fix more `ReEmpty` ICEs

closes rust-lang#65553

r? @pnkfelix