Rollup of 8 pull requests #39735
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Rollup of 8 pull requests #39735
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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 rust-lang#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.
Right now we just run `shasum` on an absolute path but right now the shasum files only include filenames, so let's use `current_dir` and just the file name to only have the file name emitted.
The previous fix contained an error where `toml::encode` returned a runtime error, so this version just constructs a literal `toml::Value`.
I spent a good chunk of time tracking down a buffer overrun bug that resulted from me mistakenly thinking that `reserve` was based on the current capacity not the current length. It would be helpful if this were called out explicitly in the docs.
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.
…hton 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.
…d, r=alexcrichton 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 rust-lang#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
Don't include directory names in shasums Right now we just run `shasum` on an absolute path but right now the shasum files only include filenames, so let's use `current_dir` and just the file name to only have the file name emitted.
Actually fix manifest generation The previous fix contained an error where `toml::encode` returned a runtime error, so this version just constructs a literal `toml::Value`.
remove wrong packed struct test This UB was found by running the test under [Miri](https://github.com/solson/miri) which rejects these unsafe unaligned loads. 😄
…ichton Explicitly mention that `Vec::reserve` is based on len not capacity I spent a good chunk of time tracking down a buffer overrun bug that resulted from me mistakenly thinking that `reserve` was based on the current capacity not the current length. It would be helpful if this were called out explicitly in the docs.
Update 1.15.1 relnotes Matching what is on stable.
Updated nightly book with installing nightly instructions
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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @steveklabnik (or someone else) soon. If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes. Please see the contribution instructions for more information. |
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Iterator.nth()#39174, SpecializePartialOrd<A> for [A] where A: Ord#39642, Don't include directory names in shasums #39660, Actually fix manifest generation #39676, remove wrong packed struct test #39692, Explicitly mention thatVec::reserveis based on len not capacity #39701, Update 1.15.1 relnotes #39710, Updated nightly book with installing nightly instructions #39725