`BTreeMap::merge` optimized
This is an optimized version of https://github.com/rust-lang/rust/pull/151981. See [ACP](https://github.com/rust-lang/libs-team/issues/739#issuecomment-3873487320) for more information on `BTreeMap::merge` does.
CC @programmerjake. Let me know what you think of how I'm using `CursorMut` and `IntoIter` here and whether the unsafe code here looks good. I decided to use `ptr::read()` and `ptr::write()` to grab the value from `CursorMut` as `V` than `&mut V`, use it within the `conflict` function, and overwrite the content of conflicting key afterward.
I know this needs some polishing, especially with refactoring some redundant looking code in a nicer way, some of which could probably just be public API methods for `CursorMut`. It does pass all the tests that I currently have for `BTreeMap::merge` (inspired from `BTreeMap::append`) though, so that's good.
Add try_shrink_to and try_shrink_to_fit to Vec
Adds the functions `try_shrink_to` and `try_shrink_to_fit` to Vec to allow shrinking
in environments without global OOM handling.
The implementation differs from the tracking issue as the fallible methods return
a `TryReserveError` instead of an `AllocError` as `AllocError` is unstable and does
not contain layout information.
Tracking:
- rust-lang/rust#152350
* Add try_shrink_to and try_shrink_to_fit to Vec
Both functions are required to support shrinking a vector in
environments without global OOM handling.
* Format the try_shrink functions
* Remove excess "```" from doc
* Remove `cfg(not(no_global_oom_handling))` from rawvecinner::shrink
* Fix import cmp even if no_global_oom_handling is defined
Simplify internals of `{Rc,Arc}::default`
This commit simplifies the internal implementation of `Default` for these two pointer types to have the same performance characteristics as before (a side effect of changes in rust-lang/rust#131460) while avoid use of internal private APIs of Rc/Arc. To preserve the same codegen as before some non-generic functions needed to be tagged as `#[inline]` as well, but otherwise the same IR is produced before/after this change.
The motivation of this commit is I was studying up on the state of initialization of `Arc` and `Rc` and figured it'd be nicer to reduce the use of internal APIs and instead use public stable APIs where possible, even in the implementation itself.
We have a constant for it already (used in `RawVec` for basically the same polymorphization) so let's use it.
Conveniently, it can even be safe that way!
Pass alignments through the shim as `Alignment` (not `usize`)
We're using `Layout` on both sides, so might as well skip the transmutes back and forth to `usize`.
The mir-opt test shows that doing so allows simplifying the boxed-slice drop slightly, for example.
This commit simplifies the internal implementation of `Default` for
these two pointer types to have the same performance characteristics as
before (a side effect of changes in 131460) while avoid use of internal
private APIs of Rc/Arc. To preserve the same codegen as before some
non-generic functions needed to be tagged as `#[inline]` as well, but
otherwise the same IR is produced before/after this change.
The motivation of this commit is I was studying up on the state of
initialization of `Arc` and `Rc` and figured it'd be nicer to reduce the
use of internal APIs and instead use public stable APIs where possible,
even in the implementation itself.
We're using `Layout` on both sides, so might as well skip the transmutes back and forth to `usize`.
The mir-opt test shows that doing so allows simplifying the boxed-slice drop slightly, for example.
compiler-builtins: Remove the no-f16-f128 feature
This option was used to gate `f16` and `f128` when support across backends and targets was inconsistent. We now have the rustc builtin cfg `target_has_reliable{f16,f128}` which has taken over this usecase. Remove no-f16-f128 since it is now unused and redundant.
Add some clarifications and fixes for fmt syntax
This tries to clarify a few things regarding fmt syntax:
- The comment on `Parser::word` seems to be wrong, as that underscore-prefixed words are just fine. This was changed in https://github.com/rust-lang/rust/pull/66847.
- I struggled to follow the description of the width argument. It referred to a "second argument", but I don't know what second argument it is referring to (which is the first?). Either way, I rewrote the paragraph to try to be a little more explicit, and to use shorter sentences.
- The description of the precision argument wasn't really clear about the distinction of an Nth argument and a named argument. I added a sentence to try to emphasize the difference.
- `IDENTIFIER_OR_KEYWORD` was changed recently in https://github.com/rust-lang/reference/pull/2049 to include bare `_`. But fmt named arguments are not allowed to be a bare `_`.
Jynn Nelson