Clarify slice and Vec iteration order
While already being inferable from the doc examples, it wasn't fully specified. This is the only logical way to do a slice iterator, so I think this should be uncontroversial. It also improves the `Vec::into_iter` example to better show the order and that the iterator returns owned values.
Change `NonNull::as_uninit_*` to take self by value (as opposed to reference), matching primitive pointers.
Copied from my comment on [#75402](https://github.com/rust-lang/rust/issues/75402#issuecomment-1100496823):
> I noticed that `as_uninit_*` on pointers take `self` by value (and pointers are `Copy`), e.g. see [`as_uninit_mut`](https://doc.rust-lang.org/core/primitive.pointer.html#method.as_uninit_mut).
>
> However, on `NonNull`, these functions take `self` by reference, e.g. see the function with the same name by for `NonNull`: [`as_uninit_mut`](https://doc.rust-lang.org/std/ptr/struct.NonNull.html#method.as_uninit_mut) takes `self` by mutable reference. Even more inconsistent, [`as_uninit_slice_mut`](https://doc.rust-lang.org/std/ptr/struct.NonNull.html#method.as_uninit_slice_mut) returns a mutable reference, but takes `self` by immutable reference.
>
> I think these methods should take `self` by value for consistency. The returned lifetime is unbounded anyways and not tied to the pointer/NonNull value anyways
I realized the change is trivial (if desired) so here I am creating my first PR. I think it's not a breaking change since (it's on nightly and) `NonNull` is `Copy`; all previous usages of these methods taking `self` by reference should continue to compile. However, it might cause warnings to appear on usages of `NonNull::as_uninit_mut`, which used to require the the `NonNull` variable be declared `mut`, but now it's not necessary.
Make write/print macros eagerly drop temporaries
This PR fixes the 2 regressions in #96434 (`println` and `eprintln`) and changes all the other similar macros (`write`, `writeln`, `print`, `eprint`) to match the old pre-#94868 behavior of `println` and `eprintln`.
argument position | before #94868 | after #94868 | after this PR
--- |:---:|:---:|:---:
`write!($tmp, "…", …)` | 😡 | 😡 | 😺
`write!(…, "…", $tmp)` | 😡 | 😡 | 😺
`writeln!($tmp, "…", …)` | 😡 | 😡 | 😺
`writeln!(…, "…", $tmp)` | 😡 | 😡 | 😺
`print!("…", $tmp)` | 😡 | 😡 | 😺
`println!("…", $tmp)` | 😺 | 😡 | 😺
`eprint!("…", $tmp)` | 😡 | 😡 | 😺
`eprintln!("…", $tmp)` | 😺 | 😡 | 😺
`panic!("…", $tmp)` | 😺 | 😺 | 😺
Example of code that is affected by this change:
```rust
use std::sync::Mutex;
fn main() {
let mutex = Mutex::new(0);
print!("{}", mutex.lock().unwrap()) /* no semicolon */
}
```
You can see several real-world examples like this in the Crater links at the top of #96434. This code failed to compile prior to this PR as follows, but works after this PR.
```console
error[E0597]: `mutex` does not live long enough
--> src/main.rs:5:18
|
5 | print!("{}", mutex.lock().unwrap()) /* no semicolon */
| ^^^^^^^^^^^^---------
| |
| borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
6 | }
| -
| |
| `mutex` dropped here while still borrowed
| ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `MutexGuard`
```
Stabilize `Ipv6Addr::to_ipv4_mapped`
CC https://github.com/rust-lang/rust/issues/27709 (tracking issue for the `ip` feature which contains more
functions)
The function `Ipv6Addr::to_ipv4` is bad because it also returns an IPv4
address for the IPv6 loopback address `::1`. Stabilize
`Ipv6Addr::to_ipv4_mapped` so we can recommend that function instead.
Move remaining tests with NLL differences to revisions
Based on #97206
I've already filed issues for any important differences that I've spotted: #97252#97253#97256#97267
There is a lot here, but each commit is self-contained as a separate directory. I can split into separate PRs as wanted or needed.
Remove box syntax from rustc_mir_dataflow and rustc_mir_transform
Continuation of #87781, inspired by #97239. The usages that this PR removes have not appeared from nothing, instead the usage in `rustc_mir_dataflow` and `rustc_mir_transform` was from #80522 which split up `rustc_mir`, and which was filed before I filed #87781, so it was using the state from before my PR. But it was merged after my PR was merged, so the `box_syntax` uses were able to survive here. Outside of this introduction due to the code being outside of the master branch at the point of merging of my PR, there was only one other introduction of box syntax, in #95159. That box syntax was removed again though in #95555. Outside of that, `box_syntax` has not made its reoccurrance in compiler crates.
Avoid accidentally enabling unstable features in compilers (take 2)
This allows rustbuild to control whether crates can use nightly features or not.
It also prevents rustbuild from using nightly features itself.
This is #92261, but I fixed the CI error.
Do leak check after function pointer coercion
cc #73154
I still need to clean diagnostics just a tad, but figured I would put this up anyways.
This change is made in order to make match arm coercion order-independent.
Basically, any time we do function pointer coercion, we follow it by doing a leak check. This is necessary because the LUB code doesn't handler higher-ranked things correctly, leading us to "coerce", but use the wrong type. A proper fix is to actually fix that code (so the type returned by `unify_and` is a supertype of both `a` and `b` if `Ok`). However, that requires a more in-depth fix, likely heavily overlapping with the new subtyping changes.
Here, I've been conservative and error early if we generate unsatisfiable constraints. Note, this should *mostly* only affect NLL, since migrate mode falls back to the LUB implementation (followed by leak check), whereas NLL only does sub.
There could be other coercion code that has an order-dependence where a leak check in the coercion code might be useful. However, this is more of a spot-fix for #73154 than a "permanent" fix, since we likely want to go the other way long-term, and allow this pattern without error.
r? `@nikomatsakis`
