Add Condvar APIs not susceptible to spurious wake
Provide wait_until and wait_timeout_until helper wrappers that aren't susceptible to spurious wake.
Additionally wait_timeout_until makes it possible to more easily write code that waits for a fixed amount of time in face of spurious wakes since otherwise each user would have to do math on adjusting the duration.
Implements #47960.
RFC 2070 part 1: PanicInfo and Location API changes
This implements part of https://rust-lang.github.io/rfcs/2070-panic-implementation.html
Tracking issue: https://github.com/rust-lang/rust/issues/44489
* Move `std::panic::PanicInfo` and `std::panic::Location` to a new `core::panic` module. The two types and the `std` module were already `#[stable]` and stay that way, the new `core` module is `#[unstable]`.
* Add a new `PanicInfo::message(&self) -> Option<&fmt::Arguments>` method, which is `#[unstable]`.
* Implement `Display` for `PanicInfo` and `Location`
Remove "empty buffer" doc in read_until
This appears copied from fill_buf, but the above paragraph already indicates that a lack of delimiter at the end is EOF.
Primitive docs relevant
This fixes the documentation to show the right types in the examples for many integer methods.
I need to check if the result is correct before we merge.
This is the ideal FileType on Windows. You may not like it, but this is what peak performance looks like.
Theoretically this would fix https://github.com/rust-lang/rust/issues/46484
The current iteration of this PR should not cause existing code to break, but instead merely improves handling around reparse points. Specifically...
* Reparse points are considered to be symbolic links if they have the name surrogate bit set. Name surrogates are reparse points that effectively act like symbolic links, redirecting you to a different directory/file. By checking for this bit instead of specific tags, we become much more general in our handling of reparse points, including those added by third parties.
* If something is a reparse point but does not have the name surrogate bit set, then we ignore the fact that it is a reparse point because it is actually a file or directory directly there, despite having additional handling by drivers due to the reparse point.
* For everything which is not a symbolic link (including non-surrogate reparse points) we report whether it is a directory or a file based on the presence of the directory attribute bit.
* Notably this still preserves invariant that when `is_symlink` returns `true`, both `is_dir` and `is_file` will return `false`. The potential for breakage was far too high.
* Adds an unstable `FileTypeExt` to allow users to determine whether a symbolic link is a directory or a file, since `FileType` by design is incapable of reporting this information.
Early exit for empty HashMap (issue #38880)
Addresses issue #38880 by checking if the HashMap is empty before computing the value of the hash.
Before (integer keys)
```
running 4 tests
test empty_once ... bench: 13 ns/iter (+/- 0)
test empty_100 ... bench: 1,367 ns/iter (+/- 35)
test exist_once ... bench: 14 ns/iter (+/- 0)
test exist_100 ... bench: 1,518 ns/iter (+/- 40)
```
After
```
running 4 tests
test empty_once ... bench: 2 ns/iter (+/- 0)
test empty_100 ... bench: 221 ns/iter (+/- 0)
test exist_once ... bench: 15 ns/iter (+/- 0)
test exist_100 ... bench: 1,515 ns/iter (+/- 92)
```
When the HashMap is not empty, the performance remains the same, and when it is empty the performance is significantly improved.
Correct a few stability attributes
* `core_float_bits`, `duration_core`, `path_component_asref`, and `repr_align` were stabalized in 1.25.0 not 1.24.0.
* Impls for `NonNull` involving unstable things should remain unstable.
* `Duration` should remain stable since 1.3.0 so it appears correctly in the `std` docs.
* `cursor_mut_vec` is an impl on only stable things so should be marked stable.
