BTreeMap: comment why drain_filter's size_hint is somewhat pessimistic
The `size_hint` of the `DrainFilter` iterator doesn't adjust as you iterate. This hardly seems important to me, but there has been a comparable PR #64383 in the past. I guess a scenario is that you first iterate half the map manually and keep most of the key/value pairs in the map, and then tell the predicate to drain most of the key/value pairs and `.collect` the iterator over the remaining half of the map.
I am totally ambivalent whether this is better or not.
r? @Mark-Simulacrum
Add PartialEq impls for Vec <-> slice
This is a follow-up to #71660 and rust-lang/rfcs#2917 to add two more missing vec/slice PartialEq impls:
```
impl<A, B> PartialEq<[B]> for Vec<A> where A: PartialEq<B> { .. }
impl<A, B> PartialEq<Vec<B>> for [A] where A: PartialEq<B> { .. }
```
Since this is insta-stable, it should go through the `@rust-lang/libs` FCP process. Note that I used version 1.47.0 for the `stable` attribute because I assume this will not merge before the 1.46.0 branch is cut next week.
Replace some once(x).chain(once(y)) with [x, y] IntoIter
Now that we have by-value array iterators that are [already used](25c8c53dd9/compiler/rustc_hir/src/def.rs (L305-L307))...
For example,
```diff
- once(self.type_ns).chain(once(self.value_ns)).chain(once(self.macro_ns)).filter_map(|it| it)
+ IntoIter::new([self.type_ns, self.value_ns, self.macro_ns]).filter_map(|it| it)
```
BTreeMap: admit the existence of leaf edges in comments
The btree code is ambiguous about leaf edges (i.e., edges within leaf nodes). Iteration relies on them heavily, but some of the comments suggest there are no leaf edges (extracted from #77025)
r? @Mark-Simulacrum
BTreeMap: complete the compile-time test_variance test case
Some of the items added to the new `test_sync` belonged in the old `test_variance` as well. And fixed inconsistent paths to nearby modules.
r? @Mark-Simulacrum
Implement Make `handle_alloc_error` default to panic (for no_std + liballoc)
Related: https://github.com/rust-lang/rust/issues/66741
Guarded with `#![feature(default_alloc_error_handler)]` a default
`alloc_error_handler` is called, if a custom allocator is used and no
other custom `#[alloc_error_handler]` is defined.
Allow Weak::as_ptr and friends for unsized T
Relaxes `impl<T> Weak<T>` to `impl<T: ?Sized> Weak<T>` for the methods `rc::Weak::as_ptr`, `into_raw`, and `from_raw`.
Follow-up to #73845, which did most of the impl work to make these functions work for `T: ?Sized`.
We still have to adjust the implementation of `Weak::from_raw` here, however, because I missed a use of `ptr.is_null()` previously. This check was necessary when `into`/`from_raw` were first implemented, as `into_raw` returned `ptr::null()` for dangling weak. However, we now just (wrapping) offset dangling weaks' pointers the same as nondangling weak, so the null check is no longer necessary (or even hit). (I can submit just 17a928f as a separate PR if desired.)
As a nice side effect, moves the `fn is_dangling` definition closer to `Weak::new`, which creates the dangling weak.
This technically stabilizes that "something like `align_of_val_raw`" is possible to do. However, I believe the part of the functionality required by these methods here -- specifically, getting the alignment of a pointee from a pointer where it may be dangling iff the pointee is `Sized` -- is uncontroversial enough to stabilize these methods without a way to implement them on stable Rust.
r? `@RalfJung,` who reviewed #73845.
ATTN: This changes (relaxes) the (input) generic bounds on stable fn!
Fix Debug implementations of some of the HashMap and BTreeMap iterator types
HashMap's `ValuesMut`, BTreeMaps `ValuesMut`, IntoValues and `IntoKeys` structs were printing both keys and values on their Debug implementations. But they are iterators over either keys or values. Irrelevant values should not be visible. With this PR, they only show relevant fields.
This fixes#75297.
[Here's an example code.](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=0c79356ed860e347a0c1a205616f93b7) This prints this on nightly:
```
ValuesMut { inner: IterMut { range: [(1, "hello"), (2, "goodbye")], length: 2 } }
IntoKeys { inner: [(1, "hello"), (2, "goodbye")] }
IntoValues { inner: [(1, "hello"), (2, "goodbye")] }
[(2, "goodbye"), (1, "hello")]
```
After the patch this example prints these instead:
```
["hello", "goodbye"]
["hello", "goodbye"]
[1, 2]
["hello", "goodbye"]
```
I didn't add test cases for them, since I couldn't see any tests for Debug implementations anywhere. But please let me know if I should add it to a specific place.
r? @dtolnay
Related: https://github.com/rust-lang/rust/issues/66741
Guarded with `#![feature(default_alloc_error_handler)]` a default
`alloc_error_handler` is called, if a custom allocator is used and no
other custom `#[alloc_error_handler]` is defined.
The panic message does not contain the size anymore, because it would
pull in the fmt machinery, which would blow up the code size
significantly.
Resolve `crate` in intra-doc links properly across crates
Closes https://github.com/rust-lang/rust/issues/77193; see https://github.com/rust-lang/rust/issues/77193#issuecomment-699065946 for an explanation of what's going on here.
~~This also fixes the BTreeMap docs that have been broken for a while; see the description on the second commit for why and how.~~ Nope, see the second commit for why the link had to be changed.
r? `@Manishearth`
cc `@dylni`
`@dylni` note that this doesn't solve your original problem - now _both_ `with_code` and `crate::with_code` will be broken links. However this will fix a lot of other broken links (in particular I think https://docs.rs/sqlx/0.4.0-beta.1/sqlx/query/struct.Query.html is because of this bug). I'll open another issue for resolving additional docs in the new scope.
UI to unit test for those using Cell/RefCell/UnsafeCell
Helps with #76268.
I'm working on all files using `Cell` and moving them to unit tests when possible.
r? @matklad
Previously, `BTreeMap` tried to link to `crate::collections`, intending
for the link to go to `std/collections/index.html`. But `BTreeMap` is
defined in `alloc`, so after the fix in the previous commit, the links
instead went to `alloc/collections/index.html`, which has almost no
information.
This changes it to link to `index.html`, which only works when viewing
from `std::collections::BTreeMap`, the most common place to visit the
docs. Fixing it to work from anywhere would require the docs for
`std::collections` to be duplicated in `alloc::collections`, which in
turn would require HashMap to be `alloc` for intra-doc links to work
(https://github.com/rust-lang/rust/issues/74481).
Rust vec bench import specific rand::RngCore
Using `RngCore` import for side effects is clearer than `*` which may bring it unnecessary more stuff than needed, it is also more explicit doing so.
@pickfire change `LEN = 16384` (and pos) and `once` instead of `[0].iter()` after this.
@rustbot modify labels: +C-cleanup +A-testsuite
It's possible for method resolution to pick this method over a lower
priority stable method, causing compilation errors. Since this method
is permanently unstable, give it a name that is very unlikely to be used
in user code.
BtreeMap: refactoring around edges
Parts chipped off a more daring effort, that the btree benchmarks judge to be performance-neutral.
r? @Mark-Simulacrum
Use `Self` in docs when possible
Fixes#76542.
I used `rg '\s*//[!/]\s+fn [\w_]+\(&?self, ' .` in `library/` to find instances, I found some with that and some by manually checking.
@rustbot modify labels: C-enhancement T-doc
