Add `select_unpredictable` to force LLVM to use CMOV
Since https://reviews.llvm.org/D118118, LLVM will no longer turn CMOVs into branches if it comes from a `select` marked with an `unpredictable` metadata attribute.
This PR introduces `core::intrinsics::select_unpredictable` which emits such a `select` and uses it in the implementation of `binary_search_by`.
Clean and enable `rustdoc::unescaped_backticks` for `core/alloc/std/test/proc_macro`
I am not sure if the lint is supposed to be "ready enough" (since it is `allow` by default), but it does catch a couple issues in `core` (`alloc`, `std`, `test` and `proc_macro` are already clean), so I propose making it `warn` in all the crates rendered in the website.
Cc: `@GuillaumeGomez`
There are only 3 cases across the crates rendered in the website (`core`,
`alloc`, `std`, `proc_macro` and `test`), and they are all in `core`.
Clean them up, so that the lint can be enabled in the next commit.
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add links from `assert_eq!` docs to `debug_assert_eq!`, etc.
This adds information and links from the docs for the following macros to their debug-only versions:
* `assert_eq!`
* `assert_ne!`
* `assert_matches!`
This matches the existing documentation for the `assert!` macro.
Stabilize `const_waker`
Closes: https://github.com/rust-lang/rust/issues/102012.
For `local_waker` and `context_ext` related things, I just ~~moved them to dedicated feature gates and reused their own tracking issue (maybe it's better to open a new one later, but at least they should not be tracked under https://github.com/rust-lang/rust/issues/102012 from the beginning IMO.)~~ reused their own feature gates as suggested by ``@tgross35.``
``@rustbot`` label: +T-libs-api
r? libs-api
add `is_multiple_of` for unsigned integer types
tracking issue: https://github.com/rust-lang/rust/issues/128101
This adds the `.is_multiple_of` method on unsigned integers.
Returns `true` if `self` is an integer multiple of `rhs`, and false otherwise.
This function is equivalent to `self % rhs == 0`, except that it will not panic for `rhs == 0`. Instead, `0.is_multiple_of(0) == true`, and for any non-zero `n`, `n.is_multiple_of(0) == false`.
Fix doc nits
Many tiny changes to stdlib doc comments to make them consistent (for example "Returns foo", rather than "Return foo"), adding missing periods, paragraph breaks, backticks for monospace style, and other minor nits.
Since https://reviews.llvm.org/D118118, LLVM will no longer turn CMOVs
into branches if it comes from a `select` marked with an `unpredictable`
metadata attribute.
This PR introduces `core::intrinsics::select_unpredictable` which emits
such a `select` and uses it in the implementation of `binary_search_by`.
from_ref, from_mut: clarify documentation
This was brought up [here](https://github.com/rust-lang/rust/issues/56604#issuecomment-2143193486). The domain of quantification is generally always constrained by the type in the type signature, and I am not sure it's always worth spelling that out explicitly as that makes things exceedingly verbose. But since this was explicitly brought up, let's clarify.
Always set `result` during `finish()` in debug builders
Most functions for format builders set `self.result` after writing strings. This ensures that any further writing fails immediately rather than trying to write again.
A few `.finish()` methods and the `.finish_non_exhaustive` did have this same behavior, so update the remaining `.finish()` methods to make it consistent here.
Stabilize const `{integer}::from_str_radix` i.e. `const_int_from_str`
This PR stabilizes the feature `const_int_from_str`.
- ACP Issue: rust-lang/libs-team#74
- Implementation PR: rust-lang/rust#99322
- Part of Tracking Issue: rust-lang/rust#59133
API Change Diff:
```diff
impl {integer} {
- pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError>;
+ pub const fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError>;
}
impl ParseIntError {
- pub fn kind(&self) -> &IntErrorKind;
+ pub const fn kind(&self) -> &IntErrorKind;
}
```
This makes it easier to parse integers at compile-time, e.g.
the example from the Tracking Issue:
```rust
env!("SOMETHING").parse::<usize>().unwrap()
```
could now be achived with
```rust
match usize::from_str_radix(env!("SOMETHING"), 10) {
Ok(val) => val,
Err(err) => panic!("Invalid value for SOMETHING environment variable."),
}
```
rather than having to depend on a library that implements or manually implement the parsing at compile-time.
---
Checklist based on [Libs Stabilization Guide - When there's const involved](https://std-dev-guide.rust-lang.org/development/stabilization.html#when-theres-const-involved)
I am treating this as a [partial stabilization](https://std-dev-guide.rust-lang.org/development/stabilization.html#partial-stabilizations) as it shares a tracking issue (and is rather small), so directly opening the partial stabilization PR for the subset (feature `const_int_from_str`) being stabilized.
- [x] ping Constant Evaluation WG
- [x] no unsafe involved
- [x] no `#[allow_internal_unstable]`
- [ ] usage of `intrinsic::const_eval_select` rust-lang/rust#124625 in `from_str_radix_assert` to change the error message between compile-time and run-time
- [ ] [rust-labg/libs-api FCP](https://github.com/rust-lang/rust/pull/124941#issuecomment-2207021921)
This adds information and links from the docs for the following macros to their debug-only versions:
* `assert_eq!`
* `assert_ne!`
* `assert_matches!`
This matches the existing documentation for the `assert!` macro.
Most functions for format builders set `self.result` after writing
strings. This ensures that any further writing fails immediately rather
than trying to write again.
A few `.finish()` methods did have this same behavior, so make it
consistent here.
Make Clone::clone a lang item
I want to absorb all the logic for picking whether an Instance is LocalCopy or GloballyShared into one place. As part of this, I wanted to identify Clone shims inside `cross_crate_inlinable` and found that rather tricky. `@compiler-errors` suggested that I add a lang item for `Clone::clone` because that would produce other cleanups in the compiler.
That sounds good to me, but I have looked and I've only been able to find one.
r? compiler-errors
Stop using `unsized_const_parameters` in core/std
`feature(unsized_const_parameters)` is an incomplete feature and should not be used by core/std as it makes it can make it significantly harder to evolve the feature. It also just generally opens the possibility of introducing bugs on stable through std's backdoor.
The only usage of this feature in std is the `simd_shuffle_intrinsic` added in #119213. It doesn't seem to be used anywhere as far as I can tell so it is removed in this PR. All tests and codegen logic etc have been kept however.
r? `@workingjubilee`
Use `#[rustfmt::skip]` on some `use` groups to prevent reordering.
`use` declarations will be reformatted in #125443. Very rarely, there is a desire to force a group of `use` declarations together in a way that auto-formatting will break up. E.g. when you want a single comment to apply to a group. #126776 dealt with all of these in the codebase, ensuring that no comments intended for multiple `use` declarations would end up in the wrong place. But some people were unhappy with it.
This commit uses `#[rustfmt::skip]` to create these custom `use` groups in an idiomatic way for a few of the cases changed in #126776. This works because rustfmt treats any `use` item annotated with `#[rustfmt::skip]` as a barrier and won't reorder other `use` items around it.
r? `@cuviper`
Implement `unsigned_signed_diff`
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Implements https://github.com/rust-lang/rust/issues/126041
Gate `AsyncFn*` under `async_closure` feature
T-lang has not come to a consensus on the naming of async closure callable bounds, and as part of allowing the async closures RFC merge, we agreed to place `AsyncFn` under the same gate as `async Fn` so that these syntaxes can be evaluated in parallel.
See https://github.com/rust-lang/rfcs/pull/3668#issuecomment-2246435537
r? oli-obk
Replace some `mem::forget`'s with `ManuallyDrop`
> but I would like to see a larger effort to replace all uses of `mem::forget`.
_Originally posted by `@saethlin` in https://github.com/rust-lang/rust/issues/127584#issuecomment-2226087767_
So,
r? `@saethlin`
Sorry, I have finished writing all of this before I got your response.
Add edge-case examples to `{count,leading,trailing}_{ones,zeros}` methods
Some architectures (i386) do not define a "count leading zeros" instruction, they define a "find first set bit" instruction (`bsf`) whose result is undefined when given zero (ie none of the bits are set). Of this family of bitwise operations, I always forget which of these things is potentially undefined for zero, and I'm also not 100% sure that Rust provides a hard guarantee for the results of these methods when given zero. So I figured there are others who have these same uncertainties, and it would be good to resolve them and answer the question via extending these doc examples/tests.
See https://en.wikipedia.org/wiki/Find_first_set#Hardware_support for more info on i386 and `bsf` on zero.
Remove generic lifetime parameter of trait `Pattern`
Use a GAT for `Searcher` associated type because this trait is always implemented for every lifetime anyway.
cc #27721
Start using `#[diagnostic::do_not_recommend]` in the standard library
This commit starts using `#[diagnostic::do_not_recommend]` in the standard library to improve some error messages. In this case we just hide a certain nightly only impl as suggested in #121521
The result in not perfect yet, but at least the `Yeet` suggestion is not shown anymore. I would consider that as a minor improvement.
This commit starts using `#[diagnostic::do_not_recommend]` in the
standard library to improve some error messages. In this case we just
hide a certain nightly only impl as suggested in #121521
Forbid borrows and unsized types from being used as the type of a const generic under `adt_const_params`
Fixes#112219Fixes#112124Fixes#112125
### Motivation
Currently the `adt_const_params` feature allows writing `Foo<const N: [u8]>` this is entirely useless as it is not possible to write an expression which evaluates to a type that is not `Sized`. In order to actually use unsized types in const generics they are typically written as `const N: &[u8]` which *is* possible to provide a value of.
Unfortunately allowing the types of const parameters to contain references is non trivial (#120961) as it introduces a number of difficult questions about how equality of references in the type system should behave. References in the types of const generics is largely only useful for using unsized types in const generics.
This PR introduces a new feature gate `unsized_const_parameters` and moves support for `const N: [u8]` and `const N: &...` from `adt_const_params` into it. The goal here hopefully is to experiment with allowing `const N: [u8]` to work without references and then eventually completely forbid references in const generics.
Splitting this out into a new feature gate means that stabilization of `adt_const_params` does not have to resolve#120961 which is the only remaining "big" blocker for the feature. Remaining issues after this are a few ICEs and naming bikeshed for `ConstParamTy`.
### Implementation
The implementation is slightly subtle here as we would like to ensure that a stabilization of `adt_const_params` is forwards compatible with any outcome of `unsized_const_parameters`. This is inherently tricky as we do not support unstable trait implementations and we determine whether a type is valid as the type of a const parameter via a trait bound.
There are a few constraints here:
- We would like to *allow for the possibility* of adding a `Sized` supertrait to `ConstParamTy` in the event that we wind up opting to not support unsized types and instead requiring people to write the 'sized version', e.g. `const N: [u8; M]` instead of `const N: [u8]`.
- Crates should be able to enable `unsized_const_parameters` and write trait implementations of `ConstParamTy` for `!Sized` types without downstream crates that only enable `adt_const_params` being able to observe this (required for std to be able to `impl<T> ConstParamTy for [T]`
Ultimately the way this is accomplished is via having two traits (sad), `ConstParamTy` and `UnsizedConstParamTy`. Depending on whether `unsized_const_parameters` is enabled or not we change which trait is used to check whether a type is allowed to be a const parameter.
Long term (when stabilizing `UnsizedConstParamTy`) it should be possible to completely merge these traits (and derive macros), only having a single `trait ConstParamTy` and `macro ConstParamTy`.
Under `adt_const_params` it is now illegal to directly refer to `ConstParamTy` it is only used as an internal impl detail by `derive(ConstParamTy)` and checking const parameters are well formed. This is necessary in order to ensure forwards compatibility with all possible future directions for `feature(unsized_const_parameters)`.
Generally the intuition here should be that `ConstParamTy` is the stable trait that everything uses, and `UnsizedConstParamTy` is that plus unstable implementations (well, I suppose `ConstParamTy` isn't stable yet :P).
bors