expand vec![] to Vec::new()
The current expansion of `vec![]` calls `into_vec` on a boxed slice, which results in longer IR, and even after optimization, some unwinding artifacts are still present in the IR. This PR uses `Vec::new()` for `vec![]`.
This also allows `vec![]` to be used in const expressions.
add `unused_braces` lint
Add the lint `unused_braces` which is warn by default.
`unused_parens` is also extended and now checks anon consts.
closes#68387
r? @varkor
BTreeMap/BTreeSet: implement drain_filter
Provide an implementation of drain_filter for BTreeMap and BTreeSet. Should be optimal when the predicate picks only elements in leaf nodes with at least MIN_LEN remaining elements, which is a common case, at least when draining only a fraction of the map/set, and also when the predicate picks elements stored in internal nodes where the right subtree can easily let go of a replacement element.
The first commit adds benchmarks with an external, naive implementation. to compare how much this claimed optimality-in-some-cases is actually worth.
Rollup of 7 pull requests
Successful merges:
- #69425 (add fn make_contiguous to VecDeque)
- #69458 (improve folder name for persistent doc tests)
- #70268 (Document ThreadSanitizer in unstable-book)
- #70600 (Ensure there are versions of test code for aarch64 windows)
- #70606 (Clean up E0466 explanation)
- #70614 (remove unnecessary relocation check in const_prop)
- #70623 (Fix broken link in README)
Failed merges:
r? @ghost
While for auto, try and PR builds we only want the latest commit to be
tested, that's not true for try builds: each commit pushed to the branch
is a different PR being tested, and we want multiple PRs to be tested in
parallel if there is enough demand.
Fixes#70569
Ensure there are versions of test code for aarch64 windows
Remove the `cfg` flags that were preventing some tests from running on `aarch64-pc-windows-msvc`.
All the existing `target_os = windows` targets had the same `align()` and `size()` values, so this change just removes the `target_arch` flags.
r? @alexcrichton
improve folder name for persistent doc tests
This fixes#69411, by using the entire path as folder name and storing already visited paths in a HashMap + appending a number to the file name for duplicates.
The current webrender commit occasionally fails without a reason, and
the latest webrender commit is missing a dependency on our Windows
builders. It's not worth installing an extra dependency for cargotest,
and the spurious failure makes keeping this test not worth it.
more clippy fixes
* use is_empty() instead of len comparison (clippy::len_zero)
* use if let instead of while let loop that never loops (clippy::never_loop)
* remove redundant returns (clippy::needless_return)
* remove redundant closures (clippy::redundant_closure)
* use if let instead of match and wildcard pattern (clippy::single_match)
* don't repeat field names redundantly (clippy::redundant_field_names)
r? @Centril
Fix incorrect documentation for `str::{split_at, split_at_mut}`
The documentation for each method currently states:
> Panics if `mid` is not on a UTF-8 code point boundary, or if it is beyond the last code point of the string slice.
However, this is not consistent with the real behavior, or that of the corresponding methods for `[T]` slices. A comment inside each of the `str` methods states:
> is_char_boundary checks that the index is in [0, .len()]
That is what I would expect the behavior to be, and in fact this seems to be the real behavior. For example ([playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=8e03dcc209d4dd176df2297523f9fee1)):
```rust
fn main() {
// Prints ("abc", "") and doesn't panic
println!("{:?}", "abc".split_at(3));
}
```
In this case, I would interpret "the last code point of the string slice" to mean the byte at index 2 in UTF-8. However, it is possible to pass an index of 3, which is definitely "beyond the last code point of the string slice".
I think that this is much clearer, but feel free to bikeshed.
