Optimize decimal formatting of 128-bit integers
## Description
This PR optimizes the `udivmod_1e19` function, which is used for formatting 128-bit integers, based on the algorithm provided in \[1\]. This optimization improves performance of formatting 128-bit integers, especially on 64-bit architectures. It also slightly reduces the output binary size.
## Assembler comparison
https://godbolt.org/z/YrG5zY
## Performance
#### previous results
```
test fmt::write_u128_max ... bench: 552 ns/iter (+/- 4)
test fmt::write_u128_min ... bench: 125 ns/iter (+/- 2)
```
#### new results
```
test fmt::write_u128_max ... bench: 205 ns/iter (+/- 13)
test fmt::write_u128_min ... bench: 129 ns/iter (+/- 5)
```
## Reference
\[1\] T. Granlund and P. Montgomery, “Division by Invariant Integers Using Multiplication” in Proc. of the SIGPLAN94 Conference on Programming Language Design and Implementation, 1994, pp. 61–72
Remove requirement that forces symmetric and transitive PartialEq impls to exist
### Counterexample of symmetry:
If you [have](https://docs.rs/proc-macro2/1.0.24/proc_macro2/struct.Ident.html#impl-PartialEq%3CT%3E) an impl like:
```rust
impl<T> PartialEq<T> for Ident
where
T: ?Sized + AsRef<str>
```
then Rust will not even allow the symmetric impl to exist.
```console
error[E0210]: type parameter `T` must be covered by another type when it appears before the first local type (`Ident`)
--> src/main.rs:9:6
|
9 | impl<T> PartialEq<Ident> for T where T: ?Sized + AsRef<str> {
| ^ type parameter `T` must be covered by another type when it appears before the first local type (`Ident`)
|
= note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local, and no uncovered type parameters appear before that first local type
= note: in this case, 'before' refers to the following order: `impl<..> ForeignTrait<T1, ..., Tn> for T0`, where `T0` is the first and `Tn` is the last
```
<br>
### Counterexample of transitivity:
Consider these two existing impls from `regex` and `clap`:
```rust
// regex
/// An inline representation of `Option<char>`.
pub struct Char(u32);
impl PartialEq<char> for Char {
fn eq(&self, other: &char) -> bool {
self.0 == *other as u32
}
}
```
```rust
// clap
pub(crate) enum KeyType {
Short(char),
Long(OsString),
Position(u64),
}
impl PartialEq<char> for KeyType {
fn eq(&self, rhs: &char) -> bool {
match self {
KeyType::Short(c) => c == rhs,
_ => false,
}
}
}
```
It's nice to be able to add `PartialEq<proc_macro::Punct> for char` in libproc_macro (https://github.com/rust-lang/rust/pull/80595), but it makes no sense to force an `impl PartialEq<Punct> for Char` and `impl PartialEq<Punct> for KeyType` in `regex` and `clap` in code that otherwise has nothing to do with proc macros.
<br>
`@rust-lang/libs`
Stabilize `core::slice::fill_with`
_Tracking issue: https://github.com/rust-lang/rust/issues/79221_
This stabilizes the `slice_fill_with` feature for Rust 1.51, following the stabilization of `slice_fill` in 1.50. This was requested by libs team members in https://github.com/rust-lang/rust/pull/79213.
This PR also adds the "memset" alias for `slice::fill_with`, mirroring the alias set on the `slice::fill` sibling API. This will ensure someone looking for "memset" will find both variants.
r? `@Amanieu`
Stabilize by-value `[T; N]` iterator `core::array::IntoIter`
Tracking issue: https://github.com/rust-lang/rust/issues/65798
This is unblocked now that `min_const_generics` has been stabilized in https://github.com/rust-lang/rust/pull/79135.
This PR does *not* include the corresponding `IntoIterator` impl, which is https://github.com/rust-lang/rust/pull/65819. Instead, an iterator can be constructed through the `new` method.
`new` would become unnecessary when `IntoIterator` is implemented and might be deprecated then, although it will stay stable.
Implement missing `AsMut<str>` for `str`
Allows `&mut str` to be taken by a Generic which requires `T` such that `T: AsMut<str>`. Motivating example:
```rust
impl<'i, T> From<T> for StructImmut<'i> where
T: AsRef<str> + 'i,
{
fn from(asref: T) -> Self {
let string: &str = asref.as_ref();
// ...
}
}
impl<'i, T> From<T> for StructMut<'i> where
T: AsMut<str> + 'i,
{
fn from(mut asmut: T) -> Self {
let string: &mut str = asmut.as_mut();
// ...
}
}
```
The Immutable form of this structure can be constructed by `StructImmut::from(s)` where `s` may be a `&String` or a `&str`, because `AsRef<str>` is implemented for `str`. However, the mutable form of the structure can be constructed in the same way **only** with a `&mut String`, and **not** with a `&mut str`.
This change does have some precedent, because as can be seen in [the Implementors](https://doc.rust-lang.org/std/convert/trait.AsMut.html#implementors), `AsMut<[T]>` is implemented for `[T]` as well as for `Vec<T>`, but `AsMut<str>` is implemented only for `String`. This would complete the symmetry.
As a trait implementation, this should be immediately stable.
stabilise `cargo test -- --include-ignored`
stabilise `cargo test -- --include-ignored`
On stable there's no way to run ignored tests as well as the normal tests.
An example use case where stabilising this would help:
Exercism has some initial tests and then some additional ignored tests that people run currently with --ignore but currently they can't run all the tests in one go without being on nightly. It would be a little more ergonomic if this flag was stablilised.
( Fixes #65770 )
I built with ./x.py build -i library/test - but as libtest is a dylib is there an easy way to invoke it manually to check it's working as expected? (I've updated the automated tests.)
Slight simplification of chars().count()
Slight simplification: No need to call len(), we can just count the number of non continuation bytes.
I can't see any reason not to do this, can you?
Stabilize `unsigned_abs`
Resolves#74913.
This PR stabilizes the `i*::unsigned_abs()` method, which returns the absolute value of an integer _as its unsigned equivalent_. This has the advantage that it does not overflow on `i*::MIN`.
I have gone ahead and used this in a couple locations throughout the repository.
Stabilize raw ref macros
This stabilizes `raw_ref_macros` (https://github.com/rust-lang/rust/issues/73394), which is possible now that https://github.com/rust-lang/rust/issues/74355 is fixed.
However, as I already said in https://github.com/rust-lang/rust/issues/73394#issuecomment-751342185, I am not particularly happy with the current names of the macros. So I propose we also change them, which means I am proposing to stabilize the following in `core::ptr`:
```rust
pub macro const_addr_of($e:expr) {
&raw const $e
}
pub macro mut_addr_of($e:expr) {
&raw mut $e
}
```
The macro name change means we need another round of FCP. Cc `````@rust-lang/libs`````
Fixes#73394
Add `core::stream::Stream`
[[Tracking issue: #79024](https://github.com/rust-lang/rust/issues/79024)]
This patch adds the `core::stream` submodule and implements `core::stream::Stream` in accordance with [RFC2996](https://github.com/rust-lang/rfcs/pull/2996). The RFC hasn't been merged yet, but as requested by the libs team in https://github.com/rust-lang/rfcs/pull/2996#issuecomment-725696389 I'm filing this PR to get the ball rolling.
## Documentatation
The docs in this PR have been adapted from [`std::iter`](https://doc.rust-lang.org/std/iter/index.html), [`async_std::stream`](https://docs.rs/async-std/1.7.0/async_std/stream/index.html), and [`futures::stream::Stream`](https://docs.rs/futures/0.3.8/futures/stream/trait.Stream.html). Once this PR lands my plan is to follow this up with PRs to add helper methods such as `stream::repeat` which can be used to document more of the concepts that are currently missing. That will allow us to cover concepts such as "infinite streams" and "laziness" in more depth.
## Feature gate
The feature gate for `Stream` is `stream_trait`. This matches the `#[lang = "future_trait"]` attribute name. The intention is that only the APIs defined in RFC2996 will use this feature gate, with future additions such as `stream::repeat` using their own feature gates. This is so we can ensure a smooth path towards stabilizing the `Stream` trait without needing to stabilize all the APIs in `core::stream` at once. But also don't start expanding the API until _after_ stabilization, as was the case with `std::future`.
__edit:__ the feature gate has been changed to `async_stream` to match the feature gate proposed in the RFC.
## Conclusion
This PR introduces `core::stream::{Stream, Next}` and re-exports it from `std` as `std::stream::{Stream, Next}`. Landing `Stream` in the stdlib has been a mult-year process; and it's incredibly exciting for this to finally happen!
---
r? `````@KodrAus`````
cc/ `````@rust-lang/wg-async-foundations````` `````@rust-lang/libs`````
BTreeMap: prevent tree from ever being owned by non-root node
This introduces a new marker type, `Dying`, which is used to note trees which are in the process of deallocation. On such trees, some fields may be in an inconsistent state as we are deallocating the tree. Unfortunately, there's not a great way to express conditional unsafety, so the methods for traversal can cause UB if not invoked correctly, but not marked as such. This is not a regression from the previous state, but rather isolates the destructive methods to solely being called on the dying state.
Make more traits of the From/Into family diagnostic items
Following traits are now diagnostic items:
- `From` (unchanged)
- `Into`
- `TryFrom`
- `TryInto`
This also adds symbols for those items:
- `into_trait`
- `try_from_trait`
- `try_into_trait`
Related: https://github.com/rust-lang/rust-clippy/pull/6620#discussion_r562482587
Print failure message on all tests that should panic, but don't
Fixes#80861. Tests with the `#[should_panic]` attribute should always print a failure message if no panic occurs, regardless of whether or not an `expected` panic message is specified.
Stabilize `Seek::stream_position` (feature `seek_convenience`)
Tracking issue: #59359
Unresolved questions from tracking issue:
- "Override `stream_len` for `File`?" → we can do that in the future, this does not block stabilization.
- "Rename to `len` and `position`?" → as noted in the tracking issue, both of these shorter names have problems (`len` is usually a cheap getter, `position` clashes with `Cursor`). I do think the current names are perfectly fine.
- "Rename `stream_position` to `tell`?" → as mentioned in [the comment bringing this up](https://github.com/rust-lang/rust/issues/59359#issuecomment-559541545), `stream_position` is more descriptive. I don't think `tell` would be a good name.
What remains to decide, is whether or not adding these methods is worth it.
Trying to shrink_to greater than capacity should be no-op
Per the discussion in https://github.com/rust-lang/rust/issues/56431, `shrink_to` shouldn't panic if you try to make a vector shrink to a capacity greater than its current capacity.
BTreeMap: test all borrowing interfaces and test more chaotic order behavior
Inspired by #81169, test what happens if you mess up order of the type with which you search (as opposed to the key type).
r? `@Mark-Simulacrum`
Add `unwrap_unchecked()` methods for `Option` and `Result`
In particular:
- `unwrap_unchecked()` for `Option`.
- `unwrap_unchecked()` and `unwrap_err_unchecked()` for `Result`.
These complement other `*_unchecked()` methods in `core` etc.
Currently there are a couple of places it may be used inside rustc (`LinkedList`, `BTree`). It is also easy to find other repositories with similar functionality.
Fixes#48278.
BTreeMap: bring back the key slice for immutable lookup
Pave the way for binary search, by reverting a bit of #73971, which banned `keys` for misbehaving while it was defined for every `BorrowType`. Adding some `debug_assert`s along the way.
r? `@Mark-Simulacrum`
libtest: Wait for test threads to exit after they report completion
Otherwise we can miss bugs where a test reports that it succeeded but then panics within a TLS destructor.
Example:
```rust
use std:🧵:sleep;
use std::time::Duration;
struct Foo;
impl Drop for Foo {
fn drop(&mut self) {
sleep(Duration::from_secs(1));
panic!()
}
}
thread_local!(static FOO: Foo = Foo);
#[test]
pub fn test() {
FOO.with(|_| {});
}
```
Before this fix, `cargo test` incorrectly reports success.
```console
$ cargo test
Finished test [unoptimized + debuginfo] target(s) in 0.01s
Running target/debug/deps/panicking_test-85130fa46b54f758
running 1 test
test test ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
$ echo $?
0
```
After this fix, the failure is visible. (The entire process is aborted due to #24479.)
```console
$ cargo test
Finished test [unoptimized + debuginfo] target(s) in 0.01s
Running target/debug/deps/panicking_test-76180625bc2ee3c9
running 1 test
thread 'test' panicked at 'explicit panic', src/main.rs:9:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal runtime error: failed to initiate panic, error 5
error: test failed, to rerun pass '--bin panicking-test'
Caused by:
process didn't exit successfully: `/tmp/panicking-test/target/debug/deps/panicking_test-76180625bc2ee3c9 --nocapture` (signal: 6, SIGABRT: process abort signal)
$ echo $?
101
```
mark raw_vec::ptr with inline
when a lot of vectors is used in a enum as in the example in #66617 if this function is not inlined and multiple cgus is used this results in huge compile times. with this fix the compile time is 6s from minutes for the example in #66617. I did not have the patience to wait for it to compile for more then 3 min.
This reduces the total complexity of checking timeouts from quadratic
to linear, and should also fix an unwrap of None on completion of an
already timed-out test.
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Prevent query cycles in the MIR inliner
r? `@eddyb` `@wesleywiser`
cc `@rust-lang/wg-mir-opt`
The general design is that we have a new query that is run on the `validated_mir` instead of on the `optimized_mir`. That query is forced before going into the optimization pipeline, so as to not try to read from a stolen MIR.
The query should not be cached cross crate, as you should never call it for items from other crates. By its very design calls into other crates can never cause query cycles.
This is a pessimistic approach to inlining, since we strictly have more calls in the `validated_mir` than we have in `optimized_mir`, but that's not a problem imo.
Otherwise we can miss bugs where a test reports that it succeeded but
then panics within a TLS destructor.
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Make std::future a re-export of core::future
After 1a764a7ef5, there are no `std::future`-specific items (except for `cfg(bootstrap)` items removed in 93eed402ad). So, instead of defining `std` own module, we can re-export the `core::future` directly.
