ignore uninhabited non-exhaustive variant fields
Fixes#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
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](https://github.com/rust-lang/rust/pull/62959#issuecomment-516016524))
- [x] Add UI tests as mentioned [here](https://github.com/rust-lang/rust/pull/62959#discussion_r307061894) (will do that soon-ish)
- [x] Fix [this new bug](https://github.com/rust-lang/rust/pull/62959#issuecomment-544732159)
**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 #25725
Rollup of 8 pull requests
Successful merges:
- #65625 (Turn crate store into a resolver output)
- #65627 (Forbid non-`structural_match` types in const generics)
- #65710 (Update cargo)
- #65729 (Update test cases for vxWorks)
- #65746 (Tweak format string error to point at arguments always)
- #65753 (Don't assert for different instance on impl trait alias)
- #65755 (Avoid ICE when adjusting bad self ty)
- #65766 (Update hashbrown to 0.6.2)
Failed merges:
r? @ghost
Tweak format string error to point at arguments always
Add secondary span labels with no text to make it clear when there's a
mismatch bewteen the positional arguments in a format string and the
arguments to the macro. This shouldn't affect experienced users, but it
should make it easier for newcomers to more clearly understand how
`format!()` and `println!()` are supposed to be used.
```
error: 2 positional arguments in format string, but there is 1 argument
--> file8.rs:2:14
|
2 | format!("{} {}", 1);
| ^^ ^^ -
```
instead of
```
error: 2 positional arguments in format string, but there is 1 argument
--> file8.rs:2:14
|
2 | format!("{} {}", 1);
| ^^ ^^
```
r? @Centril
Update cargo
6 commits in 3a9abe3f065554a7fbc59f440df2baba4a6e47ee..3ba5f27170db10af7a92f2b682e049397197b8fa
2019-10-15 15:55:35 +0000 to 2019-10-22 15:05:18 +0000
- Fix typo in `cargo install --profile` help (rust-lang/cargo#7532)
- Use stricter -Z flag parsing. (rust-lang/cargo#7531)
- Set timestamp on generated files in archive to now (rust-lang/cargo#7523)
- Support rustc's `-Z panic-abort-tests` in Cargo (rust-lang/cargo#7460)
- rustfmt for nightly changes. (rust-lang/cargo#7526)
- Allow --all-features in root of virtual workspace. (rust-lang/cargo#7525)
Turn crate store into a resolver output
Crate store (`CStore`) is a vector of data (`CrateMetadata`) associated with extern crates loaded during the current compilation session.
All crates are loaded in the resolver when resolving either paths pointing to extern prelude or `extern crate` items. (There are also a couple of crates like panic runtime that are loaded kind of like implicit `extern crate`s, but that also happens in resolve.)
The use of `CStore` from `rustc_plugin` (which is outside of the resolver) was unnecessary because legacy plugins are not added to the crate store and don't use `CrateNum`s.
So, `CStore` can be produced by the resolver instead of being kept in some really global data (`rustc_interface::Compiler`) like now.
As a result of crate store being more "local" we can now remove some locks and `Lrc`s.
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.
