Fix a misleading statement in `Iterator.nth()`
The `Iterator.nth()` documentation says "Note that all preceding elements will be consumed". I assumed from that that the preceding elements would be the *only* ones that were consumed, but in fact the returned element is consumed as well.
The way I read the documentation, I assumed that `nth(0)` would not discard anything (there are 0 preceding elements, and maybe it just peeks at the start of the iterator somehow), so I added a sentence clarifying that it does. I also rephrased it to avoid the stunted "i.e." phrasing.
Specialize `PartialOrd<A> for [A] where A: Ord`
This way we can call `cmp` instead of `partial_cmp` in the loop, removing some burden of optimizing `Option`s away from the compiler.
PR #39538 introduced a regression where sorting slices suddenly became slower, since `slice1.lt(slice2)` was much slower than `slice1.cmp(slice2) == Less`. This problem is now fixed.
To verify, I benchmarked this simple program:
```rust
fn main() {
let mut v = (0..2_000_000).map(|x| x * x * x * 18913515181).map(|x| vec![x, x ^ 3137831591]).collect::<Vec<_>>();
v.sort();
}
```
Before this PR, it would take 0.95 sec, and now it takes 0.58 sec.
I also tried changing the `is_less` lambda to use `cmp` and `partial_cmp`. Now all three versions (`lt`, `cmp`, `partial_cmp`) are equally performant for sorting slices - all of them take 0.58 sec on the
benchmark.
Tangentially, as soon as we get `default impl`, it might be a good idea to implement a blanket default impl for `lt`, `gt`, `le`, `ge` in terms of `cmp` whenever possible. Today, those four functions by default are only implemented in terms of `partial_cmp`.
r? @alexcrichton
The `Iterator.nth()` documentation says "Note that all preceding elements will be consumed". I assumed from that that the preceding elements would be the *only* ones that were consumed, but in fact the returned element is consumed as well.
The way I read the documentation, I assumed that `nth(0)` would not discard anything (as there are 0 preceding elements), so I added a sentence clarifying that it does. I also rephrased it to avoid the stunted "i.e." phrasing.
Improve format float
* Move float into mod float like in test
* Add more tests for f64 f32, lower exp, upper exp, which can come if handy in the future if we want refactor further
* Use `assert_eq` for clearer error messages
This way we can call `cmp` instead of `partial_cmp` in the loop,
removing some burden of optimizing `Option`s away from the compiler.
PR #39538 introduced a regression where sorting slices suddenly became
slower, since `slice1.lt(slice2)` was much slower than
`slice1.cmp(slice2) == Less`. This problem is now fixed.
To verify, I benchmarked this simple program:
```rust
fn main() {
let mut v = (0..2_000_000).map(|x| x * x * x * 18913515181).map(|x| vec![x, x ^ 3137831591]).collect::<Vec<_>>();
v.sort();
}
```
Before this PR, it would take 0.95 sec, and now it takes 0.58 sec.
I also tried changing the `is_less` lambda to use `cmp` and
`partial_cmp`. Now all three versions (`lt`, `cmp`, `partial_cmp`) are
equally performant for sorting slices - all of them take 0.58 sec on the
benchmark.
Fix TryFrom for i128/u128
Another case of `as` cast silent truncation being error prone.
This also adds a few missing TryFrom tests to libcoretest.
cc #33417
cc #35118
Add a name for the parameter to `TryFrom::try_from`.
Although signatures with anonymous parameters may not be deprecated or removed at this point, the team seems to agree that the ability to have an anonymous parameter is unfortunate historical baggage, and that we shouldn't create new code that uses it.
Context: https://github.com/rust-lang/rust/issues/33417#issuecomment-276933861
Provide Entry-like API for Option
This implements #39288.
I am wondering whether to use std::intrinsics::unreachable!() here. Both seems fine to me (the second match optimizes away in release mode).
branchless .filter(_).count()
I found that the branchless version is only slower if we have little to no branch misses, which usually isn't the case. I notice speedups between -5% (perfect prediction) and 60% (real world data).
Add 128-bit atomics
This is currently only supported on AArch64 since that is the only target which unconditionally supports 128-bit atomic operations.
cc #35118
Bump version, upgrade bootstrap
This commit updates the version number to 1.17.0 as we're not on that version of
the nightly compiler, and at the same time this updates src/stage0.txt to
bootstrap from freshly minted beta compiler and beta Cargo.
This commit updates the version number to 1.17.0 as we're not on that version of
the nightly compiler, and at the same time this updates src/stage0.txt to
bootstrap from freshly minted beta compiler and beta Cargo.
Extend Cell to work with non-Copy types
I'm not sure that I did this right but all of the tests pass.
I also had to move the `new()` function so that `Cell`s with non-`Copy` `T`s could be created. That wasn't in the RFC but I assume it needed to be done?
Although signatures with anonymous parameters may not be deprecated or
removed at this point, the team seems to agree that the ability to have
an anonymous parameter is unfortunate historical baggage, and that we
shouldn't create new code that uses it.
Context: https://github.com/rust-lang/rust/issues/33417#issuecomment-276933861
std: Stabilize APIs for the 1.16.0 release
This commit applies the stabilization/deprecations of the 1.16.0 release, as
tracked by the rust-lang/rust issue tracker and the final-comment-period tag.
The following APIs were stabilized:
* `VecDeque::truncate`
* `VecDeque::resize`
* `String::insert_str`
* `Duration::checked_{add,sub,div,mul}`
* `str::replacen`
* `SocketAddr::is_ipv{4,6}`
* `IpAddr::is_ipv{4,6}`
* `str::repeat`
* `Vec::dedup_by`
* `Vec::dedup_by_key`
* `Result::unwrap_or_default`
* `<*const T>::wrapping_offset`
* `<*mut T>::wrapping_offset`
* `CommandExt::creation_flags` (on Windows)
* `File::set_permissions`
* `String::split_off`
The following APIs were deprecated
* `EnumSet` - replaced with other ecosystem abstractions, long since unstable
Closes#27788Closes#35553Closes#35774Closes#36436Closes#36949Closes#37079Closes#37087Closes#37516Closes#37827Closes#37916Closes#37966Closes#38080
This commit applies the stabilization/deprecations of the 1.16.0 release, as
tracked by the rust-lang/rust issue tracker and the final-comment-period tag.
The following APIs were stabilized:
* `VecDeque::truncate`
* `VecDeque::resize`
* `String::insert_str`
* `Duration::checked_{add,sub,div,mul}`
* `str::replacen`
* `SocketAddr::is_ipv{4,6}`
* `IpAddr::is_ipv{4,6}`
* `str::repeat`
* `Vec::dedup_by`
* `Vec::dedup_by_key`
* `Result::unwrap_or_default`
* `<*const T>::wrapping_offset`
* `<*mut T>::wrapping_offset`
* `CommandExt::creation_flags` (on Windows)
* `File::set_permissions`
* `String::split_off`
The following APIs were deprecated
* `EnumSet` - replaced with other ecosystem abstractions, long since unstable
Closes#27788Closes#35553Closes#35774Closes#36436Closes#36949Closes#37079Closes#37087Closes#37516Closes#37827Closes#37916Closes#37966Closes#38080
