Mention that BTreeMap::new() doesn't allocate
I think it would be nice to mention this, so you don't have to dig through the src to look at the definition of new().
`#[deny(unsafe_op_in_unsafe_fn)]` in liballoc
This PR proposes to make use of the new `unsafe_op_in_unsafe_fn` lint, i.e. no longer consider the body of an unsafe function as an unsafe block and require explicit unsafe block to perform unsafe operations.
This has been first (partly) suggested by @Mark-Simulacrum in https://github.com/rust-lang/rust/pull/69245#issuecomment-587817065
Tracking issue for the feature: #71668.
~~Blocked on #71862.~~
r? @Mark-Simulacrum cc @nikomatsakis can you confirm that those changes are desirable? Should I restrict it to only BTree for the moment?
Reduce pointer casts in Box::into_boxed_slice
We only need to cast the pointer once to change `Box<T>` to an array
`Box<[T; 1]>`, then we can let unsized coercion return `Box<[T]>`.
Stabilize vec::Drain::as_slice
and add `AsRef<[T]> for Drain<'_, T>`.
Tracking issue: #58957. Does not stabilize `slice::IterMut::as_slice` yet. cc @cuviper
This PR proposes stabilizing just the `vec::Drain::as_slice` part of that tracking issue.
My ultimate goal here: being able to use `for<T, I: Iterator<Item=T> + AsRef<[T]>> I` to refer to `vec::IntoIter`, `vec::Drain`, and eventually `array::IntoIter`, as an approximation of the set of by-value iterators that can be "previewed" as by-ref iterators. (Actually expressing that as a trait requires GAT.)
- Use `len` more consistently for the number of elements in a vector,
because that's the usual name.
- Use `additional` more consistently for the number of elements we want
to add, because that's what `Vec::reserve()` uses.
- Use `cap` consistently rather than `capacity`.
- Plus a few other tweaks.
This increases consistency and conciseness.
impl AsRef<[T]> for vec::IntoIter<T>
Adds `impl<T> AsRef<[T]> for vec::IntoIter<T>`. This mirrors the same trait impl for [`slice::Iter`](https://doc.rust-lang.org/nightly/std/slice/struct.Iter.html). Both types already offer `fn as_slice(&self) -> &[T]`, this just adds the trait impl for `vec::IntoIter`.
If/when `fn as_slice(&self) -> &[T]` stabilizes for `vec::Drain` and `slice::IterMut`, they should get `AsRef<[T]>` impls as well. As thus, tangentially related to #58957.
My ultimate goal here: being able to use `for<T, I: Iterator<Item=T> + AsRef<[T]>> I` to refer to `vec::IntoIter`, `vec::Drain`, and eventually `array::IntoIter`, as an approximation of the set of by-value iterators that can be "previewed" as by-ref iterators. (Actually expressing that as a trait requires GAT.)
Rollup of 5 pull requests
Successful merges:
- #72260 (Spell out `Self` in async function return)
- #72996 (Remove unsused `NodeId` related APIs in hir map)
- #73010 (Update RELEASES.md)
- #73017 (Use assert_eq for liballoc test)
- #73019 (add test for #72960)
Failed merges:
r? @ghost
Override Box::<[T]>::clone_from
Avoid dropping and reallocating when cloning to an existing box if the lengths are the same.
It would be nice if this could also be specialized for `Copy` but I don't know how that works since it's not on stable. Will gladly look into it if it's deemed as a good idea.
This is my first PR with code, hope I did everything right 😄
Add Extend::{extend_one,extend_reserve}
This adds new optional methods on `Extend`: `extend_one` add a single
element to the collection, and `extend_reserve` pre-allocates space for
the predicted number of incoming elements. These are used in `Iterator`
for `partition` and `unzip` as they shuffle elements one-at-a-time into
their respective collections.
This adds new optional methods on `Extend`: `extend_one` add a single
element to the collection, and `extend_reserve` pre-allocates space for
the predicted number of incoming elements. These are used in `Iterator`
for `partition` and `unzip` as they shuffle elements one-at-a-time into
their respective collections.
Stabilization of weak-into-raw
Closes#60728.
There are also two removals of `#![feature(weak_into_raw)]` in the `src/tools/miri` submodule. How should I synchronize the changes with there?
* I can ignore it for now and once this gets merged, update the tool, send a pull request to that one and then reference the changes to rustc.
* I could try submitting the changes to miri first, but then the build would fail there, because the attribute would still be needed.
I think the first one is the correct one, extrapolating from the contributing guidelines (even though they speak about breaking the tools and this should not break it, as extra feature should not hurt).
Resolve UB in Arc/Weak interaction (2)
Use raw pointers to avoid making any assertions about the data field.
Follow up from #72479, see that PR for more detail on the motivation.
@RalfJung I was able to avoid a lot of the changes to `Weak`, by making a helper type (`WeakInner`) - because of auto-deref and because the fields have the same name, the rest of the code continues to compile.
