Add documentation to more `From::from` implementations.
For users looking at documentation through IDE popups, this gives them relevant information rather than the generic trait documentation wording “Performs the conversion”. For users reading the documentation for a specific type for any reason, this informs them when the conversion may allocate or copy significant memory versus when it is always a move or cheap copy.
Notes on specific cases:
* The new documentation for `From<T> for T` explains that it is not a conversion at all.
* Also documented `impl<T, U> Into<U> for T where U: From<T>`, the other central blanket implementation of conversion.
* The new documentation for construction of maps and sets from arrays of keys mentions the handling of duplicates. Future work could be to do this for *all* code paths that convert an iterable to a map or set.
* I did not add documentation to conversions of a specific error type to a more general error type.
* I did not add documentation to unstable code.
This change was prepared by searching for the text "From<... for" and so may have missed some cases that for whatever reason did not match. I also looked for `Into` impls but did not find any worth documenting by the above criteria.
Implement split_at_spare_mut without Deref to a slice so that the spare slice is valid
~I'm not sure I understand what's going on here correctly. And I'm pretty sure this safety comment needs to be changed. I'm just referring to the same thing that `as_mut_ptr_range` does.~ (Thanks `@RalfJung` for the guidance and clearing things up)
I tried to run https://github.com/rust-lang/miri-test-libstd on alloc with -Zmiri-track-raw-pointers, and got a failure on the test `vec::test_extend_from_within`.
I minimized the test failure into this program:
```rust
#![feature(vec_split_at_spare)]
fn main() {
Vec::<i32>::with_capacity(1).split_at_spare_mut();
}
```
The problem is that the existing implementation is actually getting a pointer range where both pointers are derived from the initialized region of the Vec's allocation, but we need the second one to be valid for the region between len and capacity. (thanks Ralf for clearing this up)
The previous implementation used slice::as_mut_ptr_range to derive the
pointer for the spare capacity slice. This is invalid, because that
pointer is derived from the initialized region, so it does not have
provenance over the uninitialized region.
Rollup of 11 pull requests
Successful merges:
- #91668 (Remove the match on `ErrorKind::Other`)
- #91678 (Add tests fixed by #90023)
- #91679 (Move core/stream/stream/mod.rs to core/stream/stream.rs)
- #91681 (fix typo in `intrinsics::raw_eq` docs)
- #91686 (Fix `Vec::reserve_exact` documentation)
- #91697 (Delete Utf8Lossy::from_str)
- #91706 (Add unstable book entries for parts of asm that are not being stabilized)
- #91709 (Replace iterator-based set construction by *Set::From<[T; N]>)
- #91716 (Improve x.py logging and defaults a bit more)
- #91747 (Add pierwill to .mailmap)
- #91755 (Fix since attribute for const_linked_list_new feature)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
For users looking at documentation through IDE popups, this gives them
relevant information rather than the generic trait documentation wording
“Performs the conversion”. For users reading the documentation for a
specific type for any reason, this informs them when the conversion may
allocate or copy significant memory versus when it is always a move or
cheap copy.
Notes on specific cases:
* The new documentation for `From<T> for T` explains that it is not a
conversion at all.
* Also documented `impl<T, U> Into<U> for T where U: From<T>`, the other
central blanket implementation of conversion.
* I did not add documentation to conversions of a specific error type to
a more general error type.
* I did not add documentation to unstable code.
This change was prepared by searching for the text "From<... for" and so
may have missed some cases that for whatever reason did not match. I
also looked for `Into` impls but did not find any worth documenting by
the above criteria.
If `Vec::push`'s capacity check fails it calls `RawVec::reserve`, which
then also does a capacity check.
This commit introduces `reserve_for_push` which skips the redundant
capacity check, for some slight compile time speed-ups.
I tried lots of minor variations on this, e.g. different inlining
attributes. This was the best one I could find.
Avoid allocations and copying in Vec::leak
The [`Vec::leak`] method (#62195) is currently implemented by calling `Vec::into_boxed_slice` and `Box::leak`. This shrinks the vector before leaking it, which potentially causes a reallocation and copies the vector's contents.
By avoiding the conversion to `Box`, we can instead leak the vector without any expensive operations, just by returning a slice reference and forgetting the `Vec`. Users who *want* to shrink the vector first can still do so by calling `shrink_to_fit` explicitly.
**Note:** This could break code that uses `Box::from_raw` to “un-leak” the slice returned by `Vec::leak`. However, the `Vec::leak` docs explicitly forbid this, so such code is already incorrect.
[`Vec::leak`]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.leak
Add truncate note to Vec::resize
A very minor addition to the `Vec::resize` documentation to point out the `truncate` method.
When I was searching for something matching `truncate` I managed to miss it, along with some colleagues. We later found it by chance. We did find `resize` however, so I was hoping to point it out in the documentation.
Optimize unnecessary check in Vec::retain
The function `vec::Vec::retain` only have two stages:
1. Nothing was deleted.
2. Some elements were deleted.
Here is an unnecessary check `if g.deleted_cnt > 0` in the loop, and it's difficult for compiler to optimize it. I split the loop into two stages manully and keep the code clean using const generics.
I write a special but common bench case for this optimization. I call retain on vec but keep all elements.
Before and after this optimization:
```
test vec::bench_retain_whole_100000 ... bench: 84,803 ns/iter (+/- 17,314)
```
```
test vec::bench_retain_whole_100000 ... bench: 42,638 ns/iter (+/- 16,910)
```
The result is expected, there are two `if`s before the optimization and one `if` after.
Fix spacing of links in inline code.
Similar to #80733, but the focus is different. This PR eliminates all occurrences of pieced-together inline code blocks like [`Box`]`<`[`Option`]`<T>>` and replaces them with good-looking ones (using HTML-syntax), like <code>[Box]<[Option]\<T>></code>. As far as I can tell, I should’ve found all of these in the standard library (regex search with `` r"`\]`|`\[`" ``) \[except for in `core::convert` where I’ve noticed other things in the docs that I want to fix in a separate PR]. In particular, unlike #80733, I’ve added almost no new instance of inline code that’s broken up into multiple links (or some link and some link-free part). I also added tooltips (the stuff in quotes for the markdown link listings) in places that caught my eye, but that’s by no means systematic, just opportunistic.
[Box]: https://doc.rust-lang.org/std/boxed/struct.Box.html "Box"
[`Box`]: https://doc.rust-lang.org/std/boxed/struct.Box.html "Box"
[Option]: https://doc.rust-lang.org/std/option/enum.Option.html "Option"
[`Option`]: https://doc.rust-lang.org/std/option/enum.Option.html "Option"
Context: I got annoyed by repeatedly running into new misformatted inline code while reading the standard library docs. I know that once issue #83997 (and/or related ones) are resolved, these changes become somewhat obsolete, but I fail to notice much progress on that end right now.
r? `@jyn514`
----------
Fix spacing for links inside code blocks, and improve link tooltips in alloc::fmt
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Fix spacing for links inside code blocks, and improve link tooltips in alloc::{rc, sync}
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Fix spacing for links inside code blocks, and improve link tooltips in alloc::string
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Fix spacing for links inside code blocks in alloc::vec
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Fix spacing for links inside code blocks in core::option
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Fix spacing for links inside code blocks, and improve a few link tooltips in core::result
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Fix spacing for links inside code blocks in core::{iter::{self, iterator}, stream::stream, poll}
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Fix spacing for links inside code blocks, and improve a few link tooltips in std::{fs, path}
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Fix spacing for links inside code blocks in std::{collections, time}
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Fix spacing for links inside code blocks in and make formatting of `&str`-like types consistent in std::ffi::{c_str, os_str}
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Fix spacing for links inside code blocks, and improve link tooltips in std::ffi
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Fix spacing for links inside code blocks, and improve a few link tooltips
in std::{io::{self, buffered::{bufreader, bufwriter}, cursor, util}, net::{self, addr}}
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Fix typo in link to `into` for `OsString` docs
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Remove tooltips that will probably become redundant in the future
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Apply suggestions from code review
Replacing `…std/primitive.reference.html` paths with just `reference`
Co-authored-by: Joshua Nelson <github@jyn.dev>
----------
Also replace `…std/primitive.reference.html` paths with just `reference` in `core::pin`
