Add forwarder methods `Stdin::lines` and `Stdin::split`, which consume
and lock a `Stdin` handle, and forward on to the corresponding `BufRead`
methods. This should make it easier for beginners to use those iterator
constructors without explicitly dealing with locks or lifetimes.
stdio_locked: add tracking issue
Add the tracking issue number #86845 to the stability attributes for the implementation in #86799.
r? `@joshtriplett`
`@rustbot` label +A-io +C-cleanup +T-libs-api
Remove unstable `io::Cursor::remaining`
Adding `io::Cursor::remaining` in #86037 caused a conflict with the implementation of `bytes::Buf` for `io::Cursor`, leading to an error in nightly, see https://github.com/rust-lang/rust/issues/86369#issuecomment-867723485.
This fixes the error by temporarily removing the `remaining` function.
r? `@yaahc`
Split MaybeUninit::write into new feature gate and stabilize it
This splits off the `MaybeUninit::write` function from the `maybe_uninit_extra` feature gate into a new `maybe_uninit_write` feature gate and stabilizes it.
Earlier work to improve the documentation of the write function: #86220
Tracking issue: #63567
[docs] Clarify behaviour of f64 and f32::sqrt when argument is negative zero
From IEEE 754 section 6.3:
> Except that squareRoot(−0) shall be −0, every numeric squareRoot result shall have a positive sign.
This will not affect ABI since the other variant of the enum is bigger.
It may break some code, but that would be very strange: usually people
don't continue after the first `Done` (or `None` for a normal iterator).
Fix linker error
Currently, `fs::hard_link` determines whether platforms have `linkat` based on the OS, and uses `link` if they don't. However, this heuristic does not work well if a platform provides `linkat` on newer versions but not on older ones. On old MacOS, this currently causes a linking error.
This commit fixes `fs::hard_link` by telling it to use `weak!` on macOS. This means that, on that operating system, we now check for `linkat` at runtime and use `link` if it is not available.
Fixes#80804.
`@rustbot` label T-libs-impl
On old macos systems, `fs::hard_link()` will follow symlinks.
This changes the test `symlink_hard_link` to exit early on
these systems, so that tests can pass.
`weak!` is needed in a test in another module. With macros
1.0, importing `weak!` would require reordering module
declarations in `std/src/lib.rs`, which is a bit too
evil.
- Add `:Sized` assertion in interpreter impl
- Use `Scalar::from_bool` instead of `ScalarInt: From<bool>`
- Remove unneeded comparison in intrinsic typeck
- Make this UB to call with undef, not just return undef in that case
special case for integer log10
Now that #80918 has been merged, this PR provides a faster version of `log10`.
The PR also adds some tests for values close to all powers of 10.
Update BTreeSet::drain_filter documentation
This commit makes the documentation of `BTreeSet::drain_filter` more
consistent with that of `BTreeMap::drain_filter` after the changes in
f0b8166870.
In particular, this explicitly documents the iteration order.
Use diagnostic items instead of lang items for rfc2229 migrations
This PR removes the `Send`, `UnwindSafe` and `RefUnwindSafe` lang items introduced in https://github.com/rust-lang/rust/pull/84730, and uses diagnostic items instead to check for `Send`, `UnwindSafe` and `RefUnwindSafe` traits for RFC2229 migrations.
r? ```@nikomatsakis```
BTree: consistently avoid unwrap_unchecked in iterators
Some iterator support functions named `_unchecked` internally use `unwrap`, some use `unwrap_unchecked`. This PR tries settling on `unwrap`. #86195 went up the same road but travelled way further and doesn't seem successful.
r? `@Mark-Simulacrum`
Revert "Add "every" as a doc alias for "all"."
This reverts commit 35450365ac (#81697) for "every" and closes#86554 in kind for "some".
The new [doc alias policy](https://std-dev-guide.rust-lang.org/documentation/doc-alias-policy.html) is that we don't want language-specific aliases like these JavaScript names, and we especially don't want to conflict with real names. While "every" is okay in the latter regard, its natural pair "some" makes a doc-search collision with `Option::Some`.
r? ```@m-ou-se```
rewrote documentation for thread::yield_now()
The old documentation suggested the use of yield_now for repeated
polling instead of discouraging it; it also made the false claim that
channels are implemented using yield_now. (They are not, except for
a corner case).
Rename some Rust 2021 lints to better names
Based on conversation in https://github.com/rust-lang/rust/issues/85894.
Rename a bunch of Rust 2021 related lints:
Lints that are officially renamed because they are already in beta or stable:
* `disjoint_capture_migration` => `rust_2021_incompatible_closure_captures`
* `or_patterns_back_compat` => `rust_2021_incompatible_or_patterns`
* `non_fmt_panic` => `non_fmt_panics`
Lints that are renamed but don't require any back -compat work since they aren't yet in stable:
* `future_prelude_collision` => `rust_2021_prelude_collisions`
* `reserved_prefix` => `rust_2021_token_prefixes`
Lints that have been discussed but that I did not rename:
* ~`non_fmt_panic` and `bare_trait_object`: is making this plural worth the headache we might cause users?~
* `array_into_iter`: I'm unsure of a good name and whether bothering users with a name change is worth it.
r? `@nikomatsakis`
Add Integer::log variants
_This is another attempt at landing https://github.com/rust-lang/rust/pull/70835, which was approved by the libs team but failed on Android tests through Bors. The text copied here is from the original issue. The only change made so far is the addition of non-`checked_` variants of the log methods._
_Tracking issue: #70887_
---
This implements `{log,log2,log10}` methods for all integer types. The implementation was provided by `@substack` for use in the stdlib.
_Note: I'm not big on math, so this PR is a best effort written with limited knowledge. It's likely I'll be getting things wrong, but happy to learn and correct. Please bare with me._
## Motivation
Calculating the logarithm of a number is a generally useful operation. Currently the stdlib only provides implementations for floats, which means that if we want to calculate the logarithm for an integer we have to cast it to a float and then back to an int.
> would be nice if there was an integer log2 instead of having to either use the f32 version or leading_zeros() which i have to verify the results of every time to be sure
_— [`@substack,` 2020-03-08](https://twitter.com/substack/status/1236445105197727744)_
At higher numbers converting from an integer to a float we also risk overflows. This means that Rust currently only provides log operations for a limited set of integers.
The process of doing log operations by converting between floats and integers is also prone to rounding errors. In the following example we're trying to calculate `base10` for an integer. We might try and calculate the `base2` for the values, and attempt [a base swap](https://www.rapidtables.com/math/algebra/Logarithm.html#log-rules) to arrive at `base10`. However because we're performing intermediate rounding we arrive at the wrong result:
```rust
// log10(900) = ~2.95 = 2
dbg!(900f32.log10() as u64);
// log base change rule: logb(x) = logc(x) / logc(b)
// log2(900) / log2(10) = 9/3 = 3
dbg!((900f32.log2() as u64) / (10f32.log2() as u64));
```
_[playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=6bd6c68b3539e400f9ca4fdc6fc2eed0)_
This is somewhat nuanced as a lot of the time it'll work well, but in real world code this could lead to some hard to track bugs. By providing correct log implementations directly on integers we can help prevent errors around this.
## Implementation notes
I checked whether LLVM intrinsics existed before implementing this, and none exist yet. ~~Also I couldn't really find a better way to write the `ilog` function. One option would be to make it a private method on the number, but I didn't see any precedent for that. I also didn't know where to best place the tests, so I added them to the bottom of the file. Even though they might seem like quite a lot they take no time to execute.~~
## References
- [Log rules](https://www.rapidtables.com/math/algebra/Logarithm.html#log-rules)
- [Rounding error playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=6bd6c68b3539e400f9ca4fdc6fc2eed0)
- [substack's tweet asking about integer log2 in the stdlib](https://twitter.com/substack/status/1236445105197727744)
- [Integer Logarithm, A. Jaffer 2008](https://people.csail.mit.edu/jaffer/III/ilog.pdf)
The old documentation suggested the use of yield_now for repeated
polling instead of discouraging it; it also made the false claim that
channels are implementing using yield_now. (They are not, except for
a corner case).
Before this, `std`'s env var getter functions would panic on
receiving certain invalid inputs. This commit makes them
return a `None` or `Err` instead.
Remove some doc aliases
As per the new doc alias policy in https://github.com/rust-lang/std-dev-guide/pull/25, this removes some controversial doc aliases:
- `malloc`, `alloc`, `realloc`, etc.
- `length` (alias for `len`)
- `delete` (alias for `remove` in collections and also file/directory deletion)
r? `@joshtriplett`
Stabilize `Seek::rewind()`
This stabilizes `Seek::rewind`. It seemed to fit into one of the existing tests, so I extended that test rather than adding a new one.
Closes#85149.
aborts: Clarify documentation and comments
In the docs for intrinsics::abort():
* Strengthen the recommendation by to use process::abort instead.
* Document the fact that it sometimes (ab)uses an LLVM debug trap and what the likely consequences are.
* State that the precise behaviour is unstable.
In the docs for process::abort():
* Promise that we have the same behaviour as C `abort()`.
* Document the likely consequences, including, specifically, the consequences on Unix.
In the internal comment for unix::abort_internal:
* Refer to the public docs for the public API functions.
* Correct and expand the description of libc::abort. Specifically:
* Do not claim that abort() unregisters signal handlers. It doesn't; it honours the SIGABRT handler.
* Discuss, extensively, the issue with abort() flushing stdio buffers.
* Describe the glibc behaviour in some detail.
Co-authored-by: Mark Wooding <mdw@distorted.org.uk>
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Fixes#40230
Add std::os::unix::fs::DirEntryExt2::file_name_ref(&self) -> &OsStr
Greetings!
This is my first PR here, so please forgive me if I've missed an important step or otherwise done something wrong. I'm very open to suggestions/fixes/corrections.
This PR adds a function that allows `std::fs::DirEntry` to vend a borrow of its filename on Unix platforms, which is especially useful for sorting. (Windows has (as I understand it) encoding differences that require an allocation.) This new function sits alongside the cross-platform [`file_name(&self) -> OsString`](https://doc.rust-lang.org/std/fs/struct.DirEntry.html#method.file_name) function.
I pitched this idea in an [internals thread](https://internals.rust-lang.org/t/allow-std-direntry-to-vend-borrows-of-its-filename/14328/4), and no one objected vehemently, so here we are.
I understand features in general, I believe, but I'm not at all confident that my whole-cloth invention of a new feature string (as required by the compiler) was correct (or that the name is appropriate). Further, there doesn't appear to be a test for the sibling `ino` function, so I didn't add one for this similarly trivial function either. If it's desirable that I should do so, I'd be happy to [figure out how to] do that.
The following is a trivial sample of a use-case for this function, in which directory entries are sorted without any additional allocations:
```rust
use std::os::unix::fs::DirEntryExt;
use std::{fs, io};
fn main() -> io::Result<()> {
let mut entries = fs::read_dir(".")?.collect::<Result<Vec<_>, io::Error>>()?;
entries.sort_unstable_by(|a, b| a.file_name_ref().cmp(b.file_name_ref()));
for p in entries {
println!("{:?}", p);
}
Ok(())
}
```
And withdraw the allegation of "abuse".
Adapted from a suggestion by @m-ou-se.
Co-authored-by: Mara Bos <m-ou.se@m-ou.se>
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
In the docs for intrinsics::abort():
* Strengthen the recommendation by to use process::abort instead.
* Document the fact that it (ab)uses an LLVM debug trap and what the
likely consequences are.
* State that the precise behaviour is unstable.
In the docs for process::abort():
* Promise that we have the same behaviour as C `abort()`.
* Document the likely consequences, including, specifically, the
consequences on Unix.
In the internal comment for unix::abort_internal:
* Refer to the public docs for the public API functions.
* Correct and expand the description of libc::abort. Specifically:
* Do not claim that abort() unregisters signal handlers. It doesn't;
it honours the SIGABRT handler.
* Discuss, extensively, the issue with abort() flushing stdio buffers.
* Describe the glibc behaviour in some detail.
Co-authored-by: Mark Wooding <mdw@distorted.org.uk>
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Rollup of 8 pull requests
Successful merges:
- #86477 (E0716: clarify that equivalent code example is erroneous)
- #86623 (Add check to ensure error code explanations are not removed anymore even if not emitted)
- #86856 (Make x.py less verbose on failures)
- #86858 (Stabilize `string_drain_as_str`)
- #86859 (Add a regression test for issue-69323)
- #86862 (re-export SwitchIntEdgeEffects)
- #86864 (Add missing code example for Write::write_vectored)
- #86874 (Bump deps)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Add examples to the various methods of `core::task::Poll`
This improves the documentation of the various methods of [`core::task::Poll`](https://doc.rust-lang.org/std/task/enum.Poll.html). These currently have fairly simple docs with no examples. This PR changes these methods to be closer to `core::option::Option` and adds usage examples (and importantly: tests!) to `Poll`'s methods.
cc/ `@rust-lang/wg-async-foundations`
## Screenshots
<details>
<summary>View generated rustdoc page</summary>
<image src="https://user-images.githubusercontent.com/2467194/123286616-59ee9b00-d50e-11eb-9e02-40269070f904.png" alt="Poll in core::task"></details>
core: add unstable no_fp_fmt_parse to disable float formatting code
In some projects (e.g. kernel), floating point is forbidden. They can disable
hardware floating point support and use `+soft-float` to avoid fp instructions
from being generated, but as libcore contains the formatting code for `f32`
and `f64`, some fp intrinsics are depended. One could define stubs for these
intrinsics that just panic [1], but it means that if any formatting functions
are accidentally used, mistake can only be caught during the runtime rather
than during compile-time or link-time, and they consume a lot of space without
LTO.
This patch provides an unstable cfg `no_fp_fmt_parse` to disable these.
A panicking stub is still provided for the `Debug` implementation (unfortunately)
because there are some SIMD types that use `#[derive(Debug)]`.
[1]: https://lkml.org/lkml/2021/4/14/1028
Stabilize `str::from_utf8_unchecked` as `const`
This stabilizes `unsafe fn str::from_utf8_unchecked` as `const` pending FCP on #75196. By the time FCP finishes, the beta will have already been cut, so I've set 1.55 as the stable-since version.
(should also be +relnotes but I don't have the permission to do that)
r? `@m-ou-se`
Closes#75196
Remove the deprecated `core::raw` and `std::raw` module.
A few months has passed since #84207. I think now it's time for the final removal.
Closes#27751.
r? `@m-ou-se`
When using `process::Command` on Windows, environment variable names must be case-preserving but case-insensitive
When using `Command` to set the environment variables, the key should be compared as uppercase Unicode but when set it should preserve the original case.
Fixes#85242
alloc: `no_global_oom_handling`: disable `new()`s, `pin()`s, etc.
They are infallible, and could not be actually used because
they will trigger an error when monomorphized, but it is better
to just remove them.
Link: https://github.com/Rust-for-Linux/linux/pull/402
Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
add owned locked stdio handles
Add stderr_locked, stdin_locked, and stdout_locked free functions
to obtain owned locked stdio handles in a single step. Also add
into_lock methods to consume a stdio handle and return an owned
lock. These methods will make it easier to use locked stdio
handles without having to deal with lifetime problems or keeping
bindings to the unlocked handles around.
Fixes#85383; enables #86412.
r? `@joshtriplett`
`@rustbot` label +A-io +C-enhancement +D-newcomer-roadblock +T-libs-api
More ErrorKinds for common errnos
From the commit message of the main commit here (as revised):
```
There are a number of IO error situations which it would be very
useful for Rust code to be able to recognise without having to resort
to OS-specific code. Taking some Unix examples, `ENOTEMPTY` and
`EXDEV` have obvious recovery strategies. Recently I was surprised to
discover that `ENOSPC` came out as `ErrorKind::Other`.
Since I am familiar with Unix I reviwed the list of errno values in
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html
Here, I add those that most clearly seem to be needed.
`@CraftSpider` provided information about Windows, and references, which
I have tried to take into account.
This has to be insta-stable because we can't sensibly have a different
set of ErrorKinds depending on a std feature flag.
I have *not* added these to the mapping tables for any operating
systems other than Unix and Windows. I hope that it is OK to add them
now for Unix and Windows now, and maybe add them to other OS's mapping
tables as and when someone on that OS is able to consider the
situation.
I adopted the general principle that it was usually a bad idea to map
two distinct error values to the same Rust error code. I notice that
this principle is already violated in the case of `EACCES` and
`EPERM`, which both map to `PermissionDenied`. I think this was
probably a mistake but it would be quite hard to change now, so I
don't propose to do anything about that.
However, for Windows, there are sometimes different error codes for
identical situations. Eg there are WSA* versions of some error
codes as well as ERROR_* ones. Also Windows seems to have a great
many more erorr codes. I don't know precisely what best practice
would be for Windows.
```
<strike>
```
Errno values I wasn't sure about so *haven't* included:
EMFILE ENFILE ENOBUFS ENOLCK:
These are all fairly Unix-specific resource exhaustion situations.
In practice it seemed not very likely to me that anyone would want
to handle these differently to `Other`.
ENOMEM ERANGE EDOM EOVERFLOW
Normally these don't get exposed to the Rust callers I hope. They
don't tend to come out of filesystem APIs.
EILSEQ
Hopefully Rust libraries open files in binary mode and do the
converstion in Rust. So Rust code ought not to be exposed to
EILSEQ.
EIO
The range of things that could cause this is troublesome. I found
it difficult to describe. I do think it would be useful to add this
at some point, because EIO on a filesystem operation is much more
serious than most other errors.
ENETDOWN
I wasn't sure if this was useful or, indeed, if any modern systems
use it.
ENOEXEC
It is not clear to me how a Rust program could respond to this. It
seems rather niche.
EPROTO ENETRESET ENODATA ENOMSG ENOPROTOOPT ENOSR ENOSTR ETIME
ENOTRECOVERABLE EOWNERDEAD EBADMSG EPROTONOSUPPORT EPROTOTYPE EIDRM
These are network or STREAMS related errors which I have never in
my own Unix programming found the need to do anything with. I think
someone who understands these better should be the one to try to
find good Rust names and descriptions for them.
ENOTTY ENXIO ENODEV EOPNOTSUPP ESRCH EALREADY ECANCELED ECHILD
EINPROGRESS
These are very hard to get unless you're already doing something
very Unix-specific, in which case the raw_os_error interface is
probably more suitable than relying on the Rust ErrorKind mapping.
EFAULT EBADF
These would seem to be the result of application UB.
```
</strike>
<i>(omitted errnos are discussed below, especially in https://github.com/rust-lang/rust/pull/79965#issuecomment-810468334)
In some projects (e.g. kernel), floating point is forbidden. They can disable
hardware floating point support and use `+soft-float` to avoid fp instructions
from being generated, but as libcore contains the formatting code for `f32`
and `f64`, some fp intrinsics are depended. One could define stubs for these
intrinsics that just panic [1], but it means that if any formatting functions
are accidentally used, mistake can only be caught during the runtime rather
than during compile-time or link-time, and they consume a lot of space without
LTO.
This patch provides an unstable cfg `no_fp_fmt_parse` to disable these.
A panicking stub is still provided for the `Debug` implementation (unfortunately)
because there are some SIMD types that use `#[derive(Debug)]`.
[1]: https://lkml.org/lkml/2021/4/14/1028
Fix double import in wasm thread
The `unsupported` type is imported two times, as `super::unsupported` and as `crate::sys::unsupported`, throwing an error. Remove `super::unsupported` in favor of the other.
As reported in #86802.
Fix#86802
Remove & from Command::args calls in documentation
Now that arrays implement `IntoIterator`, using `&` is no longer necessary. This makes examples easier to understand.
Merge `sys_common::bytestring` back into `os_str_bytes`
`bytestring` contains code for correctly debug formatting a byte slice (`[u8]`). This functionality is and has historically only been used to provide the debug formatting of byte-based os-strings (on unix etc.).
Having this functionality in the separate `bytestring` module was useful in the past to reduce duplication, as [when it was added](https://github.com/rust-lang/rust/pull/46798) `os_str_bytes` was still split into `sys::{unix, redox, wasi, etc.}::os_str`. However, now that is no longer the case, there is not much reason for the `bytestring` functionality to be separate from `os_str_bytes`; I don't think it is very likely that another part of std will need to handle formatting byte strings that are not os-strings in the future (everything should be `utf8`). This is why this PR merges the functionality of `bytestring` directly into the debug implementation in `os_str_bytes`.
add `track_path::path` fn for usage in `proc_macro`s
Adds a way to declare a dependency on external files without including them, to either re-trigger the build of a file as well as covering the use case of including dependencies within the `rustc` invocation, such that tools like `sccache`/`cachepot` are able to handle references to external files which are not included.
Ref #73921
They are infallible, and could not be actually used because
they will trigger an error when monomorphized, but it is better
to just remove them.
Link: https://github.com/Rust-for-Linux/linux/pull/402
Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
The `unsupported` type is imported two times, as `super::unsupported` and as `crate::sys::unsupported`, throwing an error. Remove `super::unsupported` in favor of the other.
Add linked list cursor end methods
I add several methods to `LinkedList::CursorMut` and `LinkedList::Cursor`. These methods allow you to access/manipulate the ends of a list via the cursor. This is especially helpful when scanning through a list and reordering. For example:
```rust
let mut c = ll.back_cursor_mut();
let mut moves = 10;
while c.current().map(|x| x > 5).unwrap_or(false) {
let n = c.remove_current();
c.push_front(n);
if moves > 0 { break; } else { moves -= 1; }
}
```
I encountered this problem working on my bachelors thesis doing graph index manipulation.
While this problem can be avoided by splicing, it is awkward. I asked about the problem [here](https://internals.rust-lang.org/t/linked-list-cursurmut-missing-methods/14921/4) and it was suggested I write a PR.
All methods added consist of
```rust
Cursor::front(&self) -> Option<&T>;
Cursor::back(&self) -> Option<&T>;
CursorMut::front(&self) -> Option<&T>;
CursorMut::back(&self) -> Option<&T>;
CursorMut::front_mut(&mut self) -> Option<&mut T>;
CursorMut::back_mut(&mut self) -> Option<&mut T>;
CursorMut::push_front(&mut self, elt: T);
CursorMut::push_back(&mut self, elt: T);
CursorMut::pop_front(&mut self) -> Option<T>;
CursorMut::pop_back(&mut self) -> Option<T>;
```
#### Design decisions:
I tried to remain as consistent as possible with what was already present for linked lists.
The methods `front`, `front_mut`, `back` and `back_mut` are identical to their `LinkedList` equivalents.
I tried to make the `pop_front` and `pop_back` methods work the same way (vis a vis the "ghost" node) as `remove_current`. I thought this was the closest analog.
`push_front` and `push_back` do not change the "current" node, even if it is the "ghost" node. I thought it was most intuitive to say that if you add to the list, current will never change.
Any feedback would be welcome 😄
Redefine `ErrorKind::Other` and stop using it in std.
This implements the idea I shared yesterday in the libs meeting when we were discussing how to handle adding new `ErrorKind`s to the standard library: This redefines `Other` to be for *user defined errors only*, and changes all uses of `Other` in the standard library to a `#[doc(hidden)]` and permanently `#[unstable]` `ErrorKind` that users can not match on. This ensures that adding `ErrorKind`s at a later point in time is not a breaking change, since the user couldn't match on these errors anyway. This way, we use the `#[non_exhaustive]` property of the enum in a more effective way.
Open questions:
- How do we check this change doesn't cause too much breakage? Will a crate run help and be enough?
- How do we ensure we don't accidentally start using `Other` again in the standard library? We don't have a `pub(not crate)` or `#[deprecated(in this crate only)]`.
cc https://github.com/rust-lang/rust/pull/79965
cc `@rust-lang/libs` `@ijackson`
r? `@dtolnay`
Add stderr_locked, stdin_locked, and stdout_locked free functions
to obtain owned locked stdio handles in a single step. Also add
into_lock methods to consume a stdio handle and return an owned
lock. These methods will make it easier to use locked stdio
handles without having to deal with lifetime problems or keeping
bindings to the unlocked handles around.
For `HashSet` and `HashMap`, this simply copies the comment from
`BinaryHeap::retain`.
For `BTreeSet` and `BTreeMap`, this adds an additional guarantee that
wasn't previously documented. I think that because these data structures
are inherently ordered and other functions guarantee ordered iteration,
it makes sense to provide this guarantee for `retain` as well.
This commit makes the documentation of `BTreeSet::drain_filter` more
consistent with that of `BTreeMap::drain_filter` after the changes in
f0b8166870.
In particular, this explicitly documents the iteration order.
The omission of Sink: Default is causing me a slight inconvenience in
a test harness. There seems little reason for this and Empty not to
be Clone and Copy too.
I have made all three of these insta-stable, because:
AIUI Copycan only be derived, and I was not able to find any
examples of how to unstably derive it. I think it is probably not
possible.
I hunted through the git history for precedent and found
79b8ad84c8
Implement `Copy` for `IoSlice`
https://github.com/rust-lang/rust/pull/69403
which was also insta-stable.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Use HTTPS links where possible
While looking at #86583, I wondered how many other (insecure) HTTP links were in `rustc`. This changes most other `http` links to `https`. While most of the links are in comments or documentation, there are a few other HTTP links that are used by CI that are changed to HTTPS.
Notes:
- I didn't change any to or in licences
- Some links don't support HTTPS :(
- Some `http` links were dead, in those cases I upgraded them to their new places (all of which used HTTPS)
Use `#[non_exhaustive]` where appropriate
Due to the std/alloc split, it is not possible to make `alloc::collections::TryReserveError::AllocError` non-exhaustive without having an unstable, doc-hidden method to construct (which negates the benefits from `#[non_exhaustive]`).
`@rustbot` label +C-cleanup +T-libs +S-waiting-on-review
Add `BuildHasher::hash_one` as unstable
Inspired by https://github.com/rust-lang/rust/pull/86140/files#diff-246941135168fbc44fce120385ee9c3156e08a1c3e2697985b56dcb8d728eedeR2416, where I wanted to write a quick test for a `Hash` implementation and it took more of a dance than I'd hoped.
It looks like this would be handy in hashtable implementations, too -- a quick look at hashbrown found two places where it needs to do the same dance:
6302512a8a/src/map.rs (L247-L270)
I wanted to get a "seems plausible" from a libs member before making a tracking issue, so random-sampling the intersection of highfive and governance gave me...
r? `@joshtriplett`
(As always, bikeshed away! And let me know if I missed something obvious again that I should have used instead.)
(Most of these are from a review by joshtriplett. Thanks!)
Fix errors in `as_pin_ref` and `as_pin_mut` in the "Adapters for
working with references" overview.
Reword some headings about transformation methods.
Reclassify `map`, `map_or`, `map_or_else`, `map_err`, etc. to more
accurately reflect which variants they transform.
Document `Debug` requirement for `get_or_insert_default`.
Reword text about `take` and `replace` to be more accurate.
Add examples for the `Product` and `Sum` traits.
Also:
Move link reference definitions closer to their uses. Warn about making
link reference definintions for `err` and `ok`. Avoid making other link
reference definitions that might conflict in the future (foreign methods
that share a name with local ones, etc.)
Write out the generics of `Option` and `Result` when the following
text refers to the type parameters.
Due to the std/alloc split, it is not possible to make
`alloc::collections::TryReserveError::AllocError` non-exhaustive without
having an unstable, doc-hidden method to construct (which negates the
benefits from `#[non_exhaustive]`.
Document associativity of iterator folds.
Document the associativity of `Iterator::fold` and
`DoubleEndedIterator::rfold` and add examples demonstrating this.
Add links to direct users to the fold of the opposite associativity.
Better errors for Debug and Display traits
Currently, if someone tries to pass value that does not implement `Debug` or `Display` to a formatting macro, they get a very verbose and confusing error message. This PR changes the error messages for missing `Debug` and `Display` impls to be less overwhelming in this case, as suggested by #85844. I was a little less aggressive in changing the error message than that issue proposed. Still, this implementation would be enough to reduce the number of messages to be much more manageable.
After this PR, information on the cause of an error involving a `Debug` or `Display` implementation would suppressed if the requirement originated within a standard library macro. My reasoning was that errors originating from within a macro are confusing when they mention details that the programmer can't see, and this is particularly problematic for `Debug` and `Display`, which are most often used via macros. It is possible that either a broader or a narrower criterion would be better. I'm quite open to any feedback.
Fixes#85844.
Add comments around code where ordering is important due for panic-safety
Iterators contain arbitrary code which may panic. Unsafe code has to be
careful to do its state updates at the right point between calls that may panic.
As requested in https://github.com/rust-lang/rust/pull/86452#discussion_r655153948
r? `@RalfJung`
Iterators contain arbitrary code which may panic. Unsafe code has to be
careful to do its state updates at the right point between calls
that may panic.
Rollup of 11 pull requests
Successful merges:
- #85054 (Revert SGX inline asm syntax)
- #85182 (Move `available_concurrency` implementation to `sys`)
- #86037 (Add `io::Cursor::{remaining, remaining_slice, is_empty}`)
- #86114 (Reopen#79692 (Format symbols under shared frames))
- #86297 (Allow to pass arguments to rustdoc-gui tool)
- #86334 (Resolve type aliases to the type they point to in intra-doc links)
- #86367 (Fix comment about rustc_inherit_overflow_checks in abs().)
- #86381 (Add regression test for issue #39161)
- #86387 (Remove `#[allow(unused_lifetimes)]` which is now unnecessary)
- #86398 (Add regression test for issue #54685)
- #86493 (Say "this enum variant takes"/"this struct takes" instead of "this function takes")
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Add `io::Cursor::{remaining, remaining_slice, is_empty}`
Tracking issue: #86369
I came across an inconvenience when answering the following [Stack Overflow](https://stackoverflow.com/questions/67831170) question.
To get the remaining slice you have to call `buff.fill_buf().unwrap()`. Which in my opinion doesn't really tell you what is returned (in the context of Cursor). To improve readability and convenience when using Cursor i propose adding the method `remaining`.
The next thing i found inconvenient (unnecessary long) was detecting if the cursor reached the end. There are a few ways this can be achieved right now:
- `buff.fill_buf().unwrap().is_empty()`
- `buff.position() >= buff.get_ref().len()`
- `buff.bytes().next().is_none()`
Which all seem a bit unintuitive, hidden in trait documentations or just a bit long for such a simple task.
Therefor i propose another method called `is_empty`, maybe with another name, since this one may leave room for interpretation on what really is empty (the underlying slice, the remaining slice or maybe the position).
Since it seemed easier to create this PR instead of an RFC i did that, if an RFC is wanted, i can close this PR and write an RFC first.
Move `available_concurrency` implementation to `sys`
This splits out the platform-specific implementation of `available_concurrency` to the corresponding platforms under `sys`. No changes are made to the implementation.
Tidy didn't lint against this code being originally added outside of `sys` because of a bug (see #84677), this PR also reverts the exclusion that was introduced in that bugfix.
Tracking issue of `available_concurrency`: #74479
Add MIR pass to lower call to `core::slice::len` into `Len` operand
During some larger experiment with range analysis I've found that code like `let l = slice.len()` produces different MIR then one found in bound checks. This optimization pass replaces terminators that are calls to `core::slice::len` with just a MIR operand and Goto terminator.
It uses some heuristics to remove the outer borrow that is made to call `core::slice::len`, but I assume it can be eliminated, just didn't find how.
Would like to express my gratitude to `@oli-obk` who helped me a lot on Zullip
Rollup of 8 pull requests
Successful merges:
- #83739 (Account for bad placeholder errors on consts/statics with trait objects)
- #85637 (document PartialEq, PartialOrd, Ord requirements more explicitly)
- #86152 (Lazify is_really_default condition in the RustdocGUI bootstrap step)
- #86156 (Fix a bug in the linkchecker)
- #86427 (Updated release note)
- #86452 (fix panic-safety in specialized Zip::next_back)
- #86484 (Do not set depth to 0 in fully_expand_fragment)
- #86491 (expand: Move some more derive logic to rustc_builtin_macros)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
fix panic-safety in specialized Zip::next_back
This was unsound since a panic in a.next_back() would result in the
length not being updated which would then lead to the same element
being revisited in the side-effect preserving code.
fixes#86443
BTree: encapsulate LeafRange better & some debug asserts
Looking at iterators again, I think #81937 didn't house enough code in `LeafRange`. Moving the API boundary a little makes things more local in navigate.rs and less complicated in map.rs.
r? `@Mark-Simulacrum`
Move `OsStringExt` and `OsStrExt` to `std::os`
Moves the `OsStringExt` and `OsStrExt` traits and implementations from `sys_common` to `os`. `sys_common` is for abstractions over `sys` and shouldn't really contain publicly exported items.
This does introduce some duplication: the traits and implementations are now duplicated in `unix`, `wasi`, `hermit`, and `sgx`. However, I would argue that this duplication is no different to how something like `MetadataExt` is duplicated in `linux`, `vxworkx`, `redox`, `solaris` etc. The duplication also matches the fact that the traits on different platforms are technically distinct types: any platform is free to add it's own extra methods to the extension trait.
Use `copy_nonoverlapping` to copy `bytes` in `String::insert_bytes`
The second copy could be made using `ptr::copy_nonoverlapping` instead of `ptr::copy`, since aliasing won't allow `self` and `bytes` to overlap. LLVM even seems to recognize this, [replacing the second `memmove` with a `memcopy`](https://rust.godbolt.org/z/Yoaa6rrGn), so this makes it so it's always applied.
Change entry point to 🛡️ against 💥💥-payloads
Guard against panic payloads panicking within entrypoints, where it is
UB to do so.
Note that there are a number of tradeoffs to consider. For instance, I
considered guarding against accidental panics inside the `rt::init` and
`rt::cleanup` code as well, as it is not all that obvious these may not
panic, but doing so would mean that we initialize certain thread-local
slots unconditionally, which has its own problems.
Fixes#86030
r? `@m-ou-se`
Guard against panic payloads panicking within entrypoints, where it is
UB to do so.
Note that there are a number of implementation approaches to consider.
Some simpler, some more complicated. This particular solution is nice in
that it also guards against accidental implementation issues in
various pieces of runtime code, something we cannot prevent statically
right now.
Fixes#86030
Alter std::cell::Cell::get_mut documentation
I felt that there was some inconsistency between between Cell and RefCell with regards to their `get_mut` method documentation: `RefCell` flags this method as "unusual" in that it takes `&mut self`, while `Cell` does not. I attempted to flag this in `Cell`s documentation as well, and point to `RefCell`s method in the case where it is required.
Find relevant parts of docs and the new version below.
The current docs for `Cell::get_mut`:
> Returns a mutable reference to the underlying data.
This call borrows Cell mutably (at compile-time) which guarantees that we possess the only reference.
And `RefCell::get_mut`:
> Returns a mutable reference to the underlying data.
This call borrows `RefCell` mutably (at compile-time) so there is no need for dynamic checks.
However be cautious: this method expects self to be mutable, which is generally not the case when using a `RefCell`. Take a look at the `borrow_mut` method instead if self isn’t mutable.
Also, please be aware that this method is only for special circumstances and is usually not what you want. In case of doubt, use `borrow_mut` instead.
My attempt to make `Cell::get_mut` clearer:
> Returns a mutable reference to the underlying data.
This call borrows `Cell` mutably (at compile-time) which guaranteesthat we possess the only reference.
However be cautious: this method expects `self` to be mutable, which is generally not the case when using a `Cell`. If you require interior mutability by reference, consider using `RefCell` which provides run-time checked mutable borrows through its `borrow_mut` method.
Stabilize span_open() and span_close().
This proposes to stabilize `Group::span_open()` and `Group::span_close()`.
These are part of the `proc_macro_span` feature gate tracked in https://github.com/rust-lang/rust/issues/54725
Most of the features gated behind `proc_macro_span` are about source location information (file path, line and column information), expansion information (parent()), source_text(), etc. Those are not ready for stabilizaiton. However, getting the span of the `(` and `)` separately instead of only of the entire `(...)` can be very useful in proc macros, and doesn't seem blocked on anything that all the other parts of `proc_macro_span` are blocked on. So, this renames the feature gate for those two functions to `proc_macro_group_span` and stabilizes them.
This was unsound since a panic in a.next_back() would result in the
length not being updated which would then lead to the same element
being revisited in the side-effect preserving code.
Add has_data_left() to BufRead
This is a continuation of #40747 and also addresses #40745. The problem with the previous PR was that it had "eof" in its method name. This PR uses a more descriptive method name, but I'm open to changing it.
Dump mingw-64's error codes into our source tree.
I have verified with these runes:
$ f=library/std/src/sys/windows/c/errors.rs
$ diff -ub <(git-cat-file blob HEAD~:$f | sort) <(cat $f | perl -pe 's/WSABASEERR \+ (\d+)/10000 + $1/e' |sort) |grep ^- |less
that this does not change any existing values.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
We're going to add many more of these.
This commit is pure code motion, plus the necessary administrivia, as
I have veried with the following runes:
$ git-diff HEAD~ | grep '^+' |sort >plus
$ git-diff HEAD~ | grep '^-' | perl -pe 's/^-/+/' |sort >min
$ diff -ub min plus |less
The output is precisely the expected `mod` and `use` directives.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
DWORD is a type alias for u32, so this makes no difference.
But this entry is anomalous and in my forthcoming commits I am going
to import many errors wholesale, and I spotted that my wholesale
import didn't match what was here.
CC: Chris Denton <christophersdenton@gmail.com>
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
use ErrorKind::*;
I don't feel confident enough about Windows things to reorder this
alphabetically
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Rely on libc for correct integer types in os/unix/net/ancillary.rs.
This PR is a small maintainability improvement. It simplifies `unix/net/ancillary.rs` in `std` by removing the `cfg_ifs` for casting to the correct integer type, and just rely on libc to define the struct correctly.
Specialize `io::Bytes::size_hint` for more types
Improve the result of `<io::Bytes as Iterator>::size_hint` for some readers. I did not manage to specialize `SizeHint` for `io::Cursor`
Side question: would it be interesting for `io::Read` to have an optional `size_hint` method ?
Linear interpolation
#71016 is a previous attempt at implementation that was closed by the author. I decided to reuse the feature request issue (#71015) as a tracking issue. A member of the rust-lang org will have to edit the original post to be formatted correctly as I am not the issue's original author.
The common name `lerp` is used because it is the term used by most code in a wide variety of contexts; it also happens to be the recently chosen name of the function that was added to C++20.
To ensure symmetry as a method, this breaks the usual ordering of the method from `lerp(a, b, t)` to `t.lerp(a, b)`. This makes the most sense to me personally, and there will definitely be discussion before stabilisation anyway.
Implementing lerp "correctly" is very dififcult even though it's a very common building-block used in all sorts of applications. A good prior reading is [this proposal](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0811r2.html#linear-interpolation) for the C++20 lerp which talks about the various guarantees, which I've simplified down to:
1. Exactness: `(0.0).lerp(start, end) == start` and `(1.0).lerp(start, end) == end`
2. Consistency: `anything.lerp(x, x) == x`
3. Monotonicity: once you go up don't go down
Fun story: the version provided in that proposal, from what I understand, isn't actually monotonic.
I messed around with a *lot* of different lerp implementations because I kind of got a bit obsessed and I ultimately landed on one that uses the fused `mul_add` instruction. Floating-point lerp lore is hard to come by, so, just trust me when I say that this ticks all the boxes. I'm only 90% certain that it's monotonic, but I'm sure that people who care deeply about this will be there to discuss before stabilisation.
The main reason for using `mul_add` is that, in general, it ticks more boxes with fewer branches to be "correct." Although it will be slower on architectures without the fused `mul_add`, that's becoming more and more rare and I have a feeling that most people who will find themselves needing `lerp` will also have an efficient `mul_add` instruction available.
Document the associativity of `Iterator::fold` and
`DoubleEndedIterator::rfold` and add examples demonstrating this.
Add links to direct users to the fold of the opposite associativity.
Make `sum()` and `product()` documentation hyperlinks refer to `Iterator` methods.
The previous linking seemed confusing: within "the sum() method on iterators", "sum()" was linked to `Sum::sum`, not `Iterator::sum`, even though the sentence is talking about the latter. I have rewritten the sentence to be, I believe, clearer, as well as changing the link destinations; applying the same change to the `Product` documentation as well as `Sum`.
I reviewed other traits in the same module and did not see similar issues, and previewed the results using `./x.py doc library/std`.
Remove methods under Implementors on trait pages
As discussed at https://github.com/rust-lang/rust/issues/84326#issuecomment-842652412.
On a trait page, the "Implementors" section currently lists all methods of each implementor. That duplicates the method definitions on the trait itself, and is usually not very useful. So the implementors are collapsed by default. This PR changes rustdoc to just not render them at all. Any documentation specific to an implementor can be found by clicking through to the implementor's page.
This moves the "portability" info inside the `<summary>` tags so it is still visible on trait pages (as originally implemented in #79201). That also means it will be visible on struct/enum pages when methods are collapsed.
Add `#[doc(hidden)]` to all implementations of `Iterator::__iterator_get_unchecked` that didn't already have it. Otherwise, due to #86145, the structs/enums with those implementations would generate documentation for them, and that documentation would have a broken link into the Iterator page. Those links were already "broken" but not detected by the link-checker, because they pointed to one of the Implementors on the Iterator page, which happened to have the right anchor name.
This reduces the Read trait's page size from 128kB to 68kB (uncompressed) and from 12,125 bytes to 9,989 bytes (gzipped
Demo:
https://hoffman-andrews.com/rust/remove-methods-implementors/std/string/struct.String.html#trait-implementationshttps://hoffman-andrews.com/rust/remove-methods-implementors/std/io/trait.Read.html#implementors
r? `@GuillaumeGomez`
Rename IoSlice(Mut)::advance to advance_slice and add IoSlice(Mut)::advance
Also changes the signature of `advance_slice` to accept a `&mut &mut [IoSlice]`, not returning anything. This will better match the `IoSlice::advance` function.
Updates https://github.com/rust-lang/rust/issues/62726.
This method on the Iterator trait is doc(hidden), and about half of
implementations were doc(hidden). This adds the attribute to the
remaining implementations.
The previous linking seemed confusing: within "the sum() method on
iterators", "sum()" was linked to `Sum::sum`, not `Iterator::sum`, even
though the sentence is talking about the latter.
I have rewritten the sentence to be, I believe, clearer, as well as
changing the link destinations; applying the same change to the
`Product` documentation as well as `Sum`.
Link reference in `dyn` keyword documentation
The "read more" sentence formatted "object safety" as inline code
instead of providing a link to more information. This PR adds a link
to the Reference about this matter, as well as the page regarding trait
objects.
---
We could also put these links in the very first line (instead of the link to the
Book) and in the first paragraph which mentions the "object safe" requirement.
Personally, I think it's good to keep the link to the Book up-front as it's more
accessible than the Reference.
Mention the `Borrow` guarantee on the `Hash` implementations for Arrays and `Vec`
To remind people like me who forget about it and send PRs to make them different, and to (probably) get a test failure if the code is changed to no longer uphold it.
optimize Eq implementation for paths
Filesystems generally have a tree-ish structure which means paths are more likely to share a prefix than a suffix. Absolute paths are especially prone to share long prefixes.
quick benchmark consisting of a search through through a vec containing the absolute paths of all (1850) files in `compiler/`:
```
# old
test path::tests::bench_path_cmp ... bench: 227,407 ns/iter (+/- 2,162)
# new
test path::tests::bench_path_cmp ... bench: 64,976 ns/iter (+/- 1,142)
```
Updates `Clone` docs for `Copy` comparison.
Quite a few people (myself included) have come under the impression that the difference between `Copy` and `Clone` is that `Copy` is cheap and `Clone` is expensive, where the actual difference is that `Copy` constrains the type to bit-wise copying, and `Clone` allows for more expensive operations. The source of this misconception is in the `Clone` docs, where the following line is in the description:
> Differs from `Copy` in that `Copy` is implicit and extremely inexpensive, while `Clone` is always explicit and may or may not be expensive.
The `Clone` documentation page also comes up before the `Copy` page on google when searching for "the difference between `Clone` and `Copy`".
This PR updates the documentation to clarify that "extremely inexpensive" means an "inexpensive bit-wise copy" to hopefully prevent future rust users from falling into this misunderstanding.
Remove `Ipv6Addr::is_unicast_site_local`
Removes the unstable method `Ipv6Addr::is_unicast_site_local`, see also #85604 where I have tried to summarize related discussion so far.
Unicast site-local addresses (`fec0::/10`) were deprecated in [IETF RFC #3879](https://datatracker.ietf.org/doc/html/rfc3879), see also [RFC #4291 Section 2.5.7](https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.7). Any new implementation must no longer support the special behaviour of site-local addresses. This is mentioned in the docs of `is_unicast_site_local` and already implemented in `is_unicast_global`, which considers addresses in `fec0::/10` to have global scope, thus overlapping with `is_unicast_site_local`.
Given that RFC #3879 was published in 2004, long before Rust existed, and it is specified that any new implementation must no longer support the special behaviour of site-local addresses, I don't see how a user would ever have a need for `is_unicast_site_local`. It is also confusing that currently both `is_unicast_site_local` and `is_unicast_global` can be `true` for an address, but an address can actually only have a single scope. The deprecating RFC mentions that Site-Local scope was confusing to work with and that the classification of an address as either Link-Local or Global better matches the mental model of users.
There has been earlier discussion of removing `is_unicast_site_local` (https://github.com/rust-lang/rust/pull/60145#issuecomment-485970669) which decided against it, but that had the incorrect assumption that the method was already stable; it is not. (This confusion arose from the placement of the unstable attribute on the entire module, instead of on individual methods, resolved in #85672)
r? `@joshtriplett` as reviewer of all the related PRs
Integrate binary search codes of binary_search_by and partition_point
For now partition_point has own binary search code piece.
It is because binary_search_by had called the comparer more times and the author (=me) wanted to avoid it.
However, now binary_search_by uses the comparer minimum times. (#74024)
So it's time to integrate them.
The appearance of the codes are a bit different but both use completely same logic.
Stabilize {std, core}::prelude::rust_*.
This stabilizes the `{core, std}::prelude::{rust_2015, rust_2018, rust_2021}` modules.
The usage of these modules as the prelude in those editions was already stabilized. This just stabilizes the modules themselves, making it possible for a user to explicitly refer to them.
Tracking issue: https://github.com/rust-lang/rust/issues/85684
FCP on the RFC that included this finished here: https://github.com/rust-lang/rfcs/pull/3114#issuecomment-840577395
Add functions `Duration::try_from_secs_{f32, f64}`
These functions allow constructing a Duration from a floating point value that could be out of range without panicking.
Tracking issue: #83400
Explain non-dropped sender recv in docs
Original senders that are still hanging around could cause
Receiver::recv to not block since this is a potential footgun
for beginners, clarify more on this in the docs for readers to
be aware about it.
Maybe it would be better to show an example of the pattern where `drop(tx)` is used when it is being cloned multiple times? Although I have seen it in quite a few articles but I am surprised that this part is not very clear with the current words without careful reading.
> If the corresponding Sender has disconnected, or it disconnects while this call is blocking, this call will wake up and return Err to indicate that no more messages can ever be received on this channel. However, since channels are buffered, messages sent before the disconnect will still be properly received.
Some words there may seemed similar if I carefully read and relate it but if I am new, I probably does not know "drop" makes it "disconnected". So I mention the words "drop" and "alive" to make it more relatable to lifetime.
Revert #85176 addition of `clone_from` for `ManuallyDrop`
Forwarding `clone_from` to the inner value changes the observable behavior, as previously the inner value would *not* be dropped by the default implementation.
Frankly, this is a super-niche case, so #85176 is welcome to argue the behavior should be otherwise! But if we overrride it, IMO documenting the behavior would be good.
Example: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=c5d0856686fa850c1d7ee16891014efb
Make minor wording changes in a few places. Move `filter` to the
"transformations" section. Add `zip` methods to the "transformations"
section. Clarify the section about `Option` iterators, and add a section
about collecting into `Option`.
Clarify that for `Result`, `or` and `or_else` can also produce a
`Result` having a different type.
Implement nonzero arithmetics for NonZero types.
Hello'all, this is my first PR to this repo.
Non-zero natural numbers are stable by addition/multiplication/exponentiation, so it makes sense to make this arithmetic possible with `NonZeroU*`.
The major pitfall is that overflowing underlying `u*` types possibly lead to underlying `0` values, which break the major invariant of `NonZeroU*`. To accommodate it, only `checked_` and `saturating_` operations are implemented.
Other variants allowing wrapped results like `wrapping_` or `overflowing_` are ruled out *de facto*.
`impl Add<u*> for NonZeroU* { .. }` was considered, as it panics on overflow which enforces the invariant, but it does not so in release mode. I considered forcing `NonZeroU*::add` to panic in release mode by deferring the check to `u*::checked_add`, but this is less explicit for the user than directly using `NonZeroU*::checked_add`.
Following `@Lokathor's` advice on zulip, I have dropped the idea.
`@poliorcetics` on Discord also suggested implementing `_sub` operations, but I'd postpone this to another PR if there is a need for it. My opinion is that it could be useful in some cases, but that it makes less sense because non-null natural numbers are not stable by subtraction even in theory, while the overflowing problem is just about technical implementation.
One thing I don't like is that the type of the `other` arg differs in every implementation: `_add` methods accept any raw positive integer, `_mul` methods only accept non-zero values otherwise the invariant is also broken, and `_pow` only seems to accept `u32` for a reason I ignore but that seems consistent throughout `std`. Maybe there is a better way to harmonize this?
This is it, Iope I haven't forgotten anything and I'll be happy to read your feedback.
Original senders that are still hanging around could cause
Receiver::recv to not block since this is a potential footgun
for beginners, clarify more on this in the docs for readers to
be aware about it.
Fix minor tidbits in sender recv doc
Co-authored-by: Dylan DPC <dylan.dpc@gmail.com>
Add example for unbounded receive loops in doc
Show the drop(tx) pattern, based on tokio docs
https://tokio-rs.github.io/tokio/doc/tokio/sync/index.html
Fix example code for drop sender recv
Fix wording in sender docs
Co-authored-by: Josh Triplett <josh@joshtriplett.org>
Fix an error in `map_or_else`. Use more descriptive text for
"don't care" in truth tables. Make minor corrections to truth tables.
Rename `makeiter` to `make_iter` in examples.
std: Stabilize wasm simd intrinsics
This commit performs two changes to stabilize Rust support for
WebAssembly simd intrinsics:
* The stdarch submodule is updated to pull in rust-lang/stdarch#1179.
* The `wasm_target_feature` feature gate requirement for the `simd128`
feature has been removed, stabilizing the name `simd128`.
This should conclude the FCP started on #74372 and...
Closes#74372
This commit performs two changes to stabilize Rust support for
WebAssembly simd intrinsics:
* The stdarch submodule is updated to pull in rust-lang/stdarch#1179.
* The `wasm_target_feature` feature gate requirement for the `simd128`
feature has been removed, stabilizing the name `simd128`.
This should conclude the FCP started on #74372 and...
Closes#74372
to_digit simplification (less jumps)
I just realised we might be able to make use of the fact that changing case in ascii is easy to help simplify to_digit some more.
It looks a bit cleaner and it looks like it's less jumps and there's less instructions in the generated assembly:
https://godbolt.org/z/84Erh5dhz
The benchmarks don't really tell me much. Maybe a slight improvement on the var radix.
Before:
```
test char::methods::bench_to_digit_radix_10 ... bench: 53,819 ns/iter (+/- 8,314)
test char::methods::bench_to_digit_radix_16 ... bench: 57,265 ns/iter (+/- 10,730)
test char::methods::bench_to_digit_radix_2 ... bench: 55,077 ns/iter (+/- 5,431)
test char::methods::bench_to_digit_radix_36 ... bench: 56,549 ns/iter (+/- 3,248)
test char::methods::bench_to_digit_radix_var ... bench: 43,848 ns/iter (+/- 3,189)
test char::methods::bench_to_digit_radix_10 ... bench: 51,707 ns/iter (+/- 10,946)
test char::methods::bench_to_digit_radix_16 ... bench: 52,835 ns/iter (+/- 2,689)
test char::methods::bench_to_digit_radix_2 ... bench: 51,012 ns/iter (+/- 2,746)
test char::methods::bench_to_digit_radix_36 ... bench: 53,210 ns/iter (+/- 8,645)
test char::methods::bench_to_digit_radix_var ... bench: 40,386 ns/iter (+/- 4,711)
test char::methods::bench_to_digit_radix_10 ... bench: 54,088 ns/iter (+/- 5,677)
test char::methods::bench_to_digit_radix_16 ... bench: 55,972 ns/iter (+/- 17,229)
test char::methods::bench_to_digit_radix_2 ... bench: 52,083 ns/iter (+/- 2,425)
test char::methods::bench_to_digit_radix_36 ... bench: 54,132 ns/iter (+/- 1,548)
test char::methods::bench_to_digit_radix_var ... bench: 41,250 ns/iter (+/- 5,299)
```
After:
```
test char::methods::bench_to_digit_radix_10 ... bench: 48,907 ns/iter (+/- 19,449)
test char::methods::bench_to_digit_radix_16 ... bench: 52,673 ns/iter (+/- 8,122)
test char::methods::bench_to_digit_radix_2 ... bench: 48,509 ns/iter (+/- 2,885)
test char::methods::bench_to_digit_radix_36 ... bench: 50,526 ns/iter (+/- 4,610)
test char::methods::bench_to_digit_radix_var ... bench: 38,618 ns/iter (+/- 3,180)
test char::methods::bench_to_digit_radix_10 ... bench: 54,202 ns/iter (+/- 6,994)
test char::methods::bench_to_digit_radix_16 ... bench: 56,585 ns/iter (+/- 8,448)
test char::methods::bench_to_digit_radix_2 ... bench: 50,548 ns/iter (+/- 1,674)
test char::methods::bench_to_digit_radix_36 ... bench: 52,749 ns/iter (+/- 2,576)
test char::methods::bench_to_digit_radix_var ... bench: 40,215 ns/iter (+/- 3,327)
test char::methods::bench_to_digit_radix_10 ... bench: 50,233 ns/iter (+/- 22,272)
test char::methods::bench_to_digit_radix_16 ... bench: 50,841 ns/iter (+/- 19,981)
test char::methods::bench_to_digit_radix_2 ... bench: 50,386 ns/iter (+/- 4,555)
test char::methods::bench_to_digit_radix_36 ... bench: 52,369 ns/iter (+/- 2,737)
test char::methods::bench_to_digit_radix_var ... bench: 40,417 ns/iter (+/- 2,766)
```
I removed the likely as it resulted in a few less instructions. (It's not been in there long - I added it in the last to_digit iteration).
fix off by one in `std::iter::Iterator` documentation
the range `(0..10)` is documented as "The even numbers from zero to ten." - should be ".. to nine".
Updated code examples and wording in move keyword documentation
Had a conversation with someone on the Rust Discord who was confused by the move keyword documentation. Some of the wording is odd sounding ("owned by value" - what else can something be owned by?). Also, some of the examples used Copy types when demonstrating move, leading to variables still being accessible in the outer scope after the move, contradicting the examples' comments.
I changed the move keyword documentation a bit, removing that odd wording and changing all the examples to use non-Copy types
Multiple improvements to RwLocks
This PR replicates #77147, #77380 and #84650 on RWLocks :
- Split `sys_common::RWLock` in `StaticRWLock` and `MovableRWLock`
- Unbox rwlocks on some platforms (Windows, Wasm and unsupported)
- Simplify `RwLock::into_inner`
Notes to reviewers :
- For each target, I copied `MovableMutex` to guess if `MovableRWLock` should be boxed.
- ~A comment says that `StaticMutex` is not re-entrant, I don't understand why and I don't know whether it applies to `StaticRWLock`.~
r? `@m-ou-se`
Filesystems generally have a tree-ish structure which means
paths are more likely to share a prefix than a suffix. Absolute paths
are especially prone to share long prefixes.
Make copy/copy_nonoverlapping fn's again
Make copy/copy_nonoverlapping fn's again, rather than intrinsics.
This a short-term change to address issue #84297.
It effectively reverts PRs #81167#81238 (and part of #82967), #83091, and parts of #79684.
Revert "implement TrustedRandomAccess for Take iterator adapter"
This reverts commit 37a5b515e9 (#83990).
The original change unintentionally caused side-effects from certain iterator chains combining `take`, `zip` and `next_back()` to be omitted which is observable by user code and thus likely a breaking change
Technically one could declare it not a breaking change since `Zip`'s API contract is silent about about its backwards iteration behavior but on the other hand there is nothing in the stable Iterator API that could justify the currently observable behavior. And either way, this impact wasn't noticed or discussed in the original PR.
Fixes#85969
Forwarding implementation for Seek trait's stream_position method
Forwarding implementations for `Seek` trait's `stream_position` were missed when it was stabilized in `1.51.0`
Add `Ipv6Addr::is_unicast`
Adds an unstable utility method `Ipv6Addr::is_unicast` under the feature flag `ip` (tracking issue: #27709).
Added for completeness with the other unicast methods (see also https://github.com/rust-lang/rust/issues/85604#issuecomment-848220455) and opposite of `is_multicast`.
Fix documentation style inconsistencies for IP addresses
Pulled out of #85655 as it is unrelated. Fixes some inconsistencies in the docs for IP addresses:
- Currently some addresses are backticked, some are not, this PR backticks everything consistently. (looks better imo)
- Lowercase hex-literals are used when writing addresses.
To remind people like me who forget about it and send PRs to make them different, and to (probably) get a test failure if the code is changed to no longer uphold it.
The "read more" sentence formatted "object safety" as inline code
instead of providing a link to more information. This PR adds a link
to the Reference about this matter, as well as the page regarding trait
objects.
Default panic message should print Box<dyn Any>
Closes#86039
Prior to this patch, the panic message from running the following code would be `thread 'main' panicked at 'Box<Any>'...`
```rust
use std::panic::panic_any;
fn main() {
panic_any(42);
}
```
This patch updates the phrasing to be more consistent. It now instead shows the following panic message:
```
thread 'main' panicked at 'Box<dyn Any>', ...
```
It's a very small fix 😄
Clarify documentation of slice sorting methods
After reading about [this](https://polkadot.network/a-polkadot-postmortem-24-05-2021/), I realized that although the documentation of these methods is not ambiguous in its current state, it is very easy to read it and erroneously assume that their exact behaviour can be relied upon to be deterministic. Although the docs make no guarantees about which index is returned when there are multiple matches, being more explicit about when and how their determinism can be relied upon should help prevent people from making this mistake in the future.
r? ``@steveklabnik``
String::remove_matches O(n^2) -> O(n)
Copy only non-matching bytes. Replace collection of matches into a
vector with iteration over rejections, exploiting the guarantee that we
mutate parts of the haystack that have already been searched over.
r? `@joshtriplett`
