When these functions were added in
https://github.com/rust-lang/rust/pull/138087
It made a relatively common pattern for emulating
these functions using an extension trait (which
internally uses `libm`) much more fragile.
If `core::f32` happened to be imported by the user
(to access a constant, say), then that import in
the module namespace would take precedence over
`f32` in the type namespace for resolving these
functions, running headfirst into the stability
attribute.
We ran into this in Color -
https://github.com/linebender/color - and chose to
release the remedial 0.3.1 and 0.2.4, to allow
downstream crates to build on `docs.rs`.
As these methods are perma-unstable, moving them
into a new module should not have any long-term
concerns, and ensures that this breakage doesn't
adversely impact anyone else.
Extend the existing tests for `f32` and `f64` with versions that include
`f16`'s new printing and parsing implementations.
Co-authored-by: Speedy_Lex <alex.ciocildau@gmail.com>
Initial implementation of `core_float_math`
Since [1], `compiler-builtins` makes a certain set of math symbols
weakly available on all platforms. This means we can begin exposing some
of the related functions in `core`, so begin this process here.
It is not possible to provide inherent methods in both `core` and `std`
while giving them different stability gates, so standalone functions are
added instead. This provides a way to experiment with the functionality
while unstable; once it is time to stabilize, they can be converted to
inherent.
For `f16` and `f128`, everything is unstable so we can move the inherent
methods.
The following are included to start:
* floor
* ceil
* round
* round_ties_even
* trunc
* fract
* mul_add
* div_euclid
* rem_euclid
* powi
* sqrt
* abs_sub
* cbrt
These mirror the set of functions that we have in `compiler-builtins`
since [1], with the exception of `powi` that has been there longer.
Details for each of the changes is in the commit messages.
Tracking issue: https://github.com/rust-lang/rust/issues/137578
[1]: https://github.com/rust-lang/compiler-builtins/pull/763
try-job: aarch64-gnu
tru-job: armhf-gnu
try-job: i686-msvc-1
try-job: test-various
try-job: x86_64-mingw-1
try-job: x86_64-mingw-2
Add `#[must_use]` to Array::map
The output of Array::map is intended to be an array of the same size, and does not modify the original in place nor is it intended for side-effects. Thus, under normal circumstances it should be consumed.
See [discussion](https://internals.rust-lang.org/t/array-map-annotate-with-must-use/22813/26).
Attaching to tracking issue #75243
The previous commit moved all test files from `std` to `core` so git
understands the move. Not all functionality is actually testable in
`core`, however, so perform move the relevant portions back. Changes
from inherent to module methods is also done since this is the form of
math operations available in `core` (as `core_float_math`).
Many float-related tests in `std` only depend on `core`, so move the
tests there. This also allows us to verify functions from
`core_float_math`.
Since the majority of test files need to be moved to `coretests`, move
the files here without any cleanup; this is done in a followup commit.
This makes git history slightly cleaner, but coretests will not build
immediately after this commit.
The output of Array::map is intended to be an array of the same size, and does not modify the
original in place nor is it intended for side-effects. Thus, under normal circumstances it should be consumed.
See [discussion](https://internals.rust-lang.org/t/array-map-annotate-with-must-use/22813/26).
Attaching to tracking issue #75243
stabilize ptr::swap_nonoverlapping in const
Closes https://github.com/rust-lang/rust/issues/133668
The blocking issue mentioned there is resolved by documentation. We may in the future actually support such code, but that is blocked on https://github.com/rust-lang/const-eval/issues/72 which is non-trivial to implement. Meanwhile, this completes stabilization of all `const fn` in `ptr`. :)
Here's a version of the problematic example to play around with:
https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=6c390452379fb593e109b8f8ee854d2a
Should be FCP'd with both `@rust-lang/libs-api` and `@rust-lang/lang` since `swap_nonoverlapping` is documented to work as an "untyped" operation but due to the limitation mentioned above, that's not entirely true during const evaluation. I expect this limitation will only be hit in niche corner cases, so the benefits of having this function work most of the time outweigh the downsides of users running into this problem. (Note that unsafe code could already hit this limitation before this PR by doing cursed pointer casts, but having it hidden inside `swap_nonoverlapping` feels a bit different.)
add next_index to Enumerate
Proposal: https://github.com/rust-lang/libs-team/issues/435
Tracking Issue: #130711
This basically just reopens#130682 but squashed and with the new function and the feature gate renamed to `next_index.`
There are two questions I have already:
- Shouldn't we add test coverage for that? I'm happy to provide some, but I might need a pointer to where these test would be.
- Maybe I could actually also add a doctest?
- For now, I just renamed the feature name in the unstable attribute to `next_index`, as well, so it matches the new name of the function. Is that okay? And can I just do that and use any string, or is there a sealed list of features defined somewhere where I also need to change the name?
Implement `pin!()` using `super let`
Tracking issue for super let: https://github.com/rust-lang/rust/issues/139076
This uses `super let` to implement `pin!()`.
This means we can remove [the hack](https://github.com/rust-lang/rust/pull/138717) we had to put in to fix https://github.com/rust-lang/rust/issues/138596.
It also means we can remove the original hack to make `pin!()` work, which used a questionable public-but-unstable field rather than a proper private field.
While `super let` is still unstable and subject to change, it seems safe to assume that future Rust will always have a way to express `pin!()` in a compatible way, considering `pin!()` is already stable.
It'd help [the experiment](https://github.com/rust-lang/rust/issues/139076) to have `pin!()` use `super let`, so we can get some more experience with it.
Ensure `swap_nonoverlapping` is really always untyped
This replaces #134954, which was arguably overcomplicated.
## Fixes#134713
Actually using the type passed to `ptr::swap_nonoverlapping` for anything other than its size + align turns out to not work, so this goes back to always erasing the types down to just bytes.
(Except in `const`, which keeps doing the same thing as before to preserve `@RalfJung's` fix from #134689)
## Fixes#134946
I'd previously moved the swapping to use auto-vectorization *on bytes*, but someone pointed out on Discord that the tail loop handling from that left a whole bunch of byte-by-byte swapping around. This goes back to manual tail handling to avoid that, then still triggers auto-vectorization on pointer-width values. (So you'll see `<4 x i64>` on `x86-64-v3` for example.)
Following `#135937` and `#136642`, tests for core and alloc are in
coretests and alloctests. Fix tidy to lint for the new paths. Also,
update comments referring to the old locations.
Some context for changes which don't match that pattern:
* library/std/src/thread/local/dynamic_tests.rs and
library/std/src/sync/mpsc/sync_tests.rs were moved under
library/std/tests/ in 332fb7e6f1d (Move std::thread_local unit tests
to integration tests, 2025-01-17) and b8ae372e483 (Move std::sync unit
tests to integration tests, 2025-01-17), respectively, so are no
longer special cases.
* There never was a library/core/tests/fmt.rs file. That comment
previously referred to src/test/ui/ifmt.rs, which was folded into
library/alloc/tests/fmt.rs in 949c96660c3 (move format! interface
tests, 2020-09-08).
remove `feature(inline_const_pat)`
Summarizing https://rust-lang.zulipchat.com/#narrow/channel/144729-t-types/topic/remove.20feature.28inline_const_pat.29.20and.20shared.20borrowck.
With https://github.com/rust-lang/types-team/issues/129 we will start to borrowck items together with their typeck parent. This is necessary to correctly support opaque types, blocking the new solver and TAIT/ATPIT stabilization with the old one. This means that we cannot really support `inline_const_pat` as they are implemented right now:
- we want to typeck inline consts together with their parent body to allow inference to flow both ways and to allow the const to refer to local regions of its parent.This means we also need to borrowck the inline const together with its parent as that's necessary to properly support opaque types
- we want the inline const pattern to participate in exhaustiveness checking
- to participate in exhaustiveness checking we need to evaluate it, which requires borrowck, which now relies on borrowck of the typeck root, which ends up checking exhaustiveness again. **This is a query cycle**.
There are 4 possible ways to handle this:
- stop typechecking inline const patterns together with their parent
- causes inline const patterns to be different than inline const exprs
- prevents bidirectional inference, we need to either fail to compile `if let const { 1 } = 1u32` or `if let const { 1u32 } = 1`
- region inference for inline consts will be harder, it feels non-trivial to support inline consts referencing local regions from the parent fn
- inline consts no longer participate in exhaustiveness checking. Treat them like `pat if pat == const { .. }` instead. We then only evaluate them after borrowck
- difference between `const { 1 }` and `const FOO: usize = 1; match x { FOO => () }`. This is confusing
- do they carry their weight if they are now just equivalent to using an if-guard
- delay exhaustiveness checking until after borrowck
- should be possible in theory, but is a quite involved change and may have some unexpected challenges
- remove this feature for now
I believe we should either delay exhaustiveness checking or remove the feature entirely. As moving exhaustiveness checking to after borrow checking is quite complex I think the right course of action is to fully remove the feature for now and to add it again once/if we've got that implementation figured out.
`const { .. }`-expressions remain stable. These seem to have been the main motivation for https://github.com/rust-lang/rfcs/issues/2920.
r? types
cc `@rust-lang/types` `@rust-lang/lang` #76001
Reduce FormattingOptions to 64 bits
This is part of https://github.com/rust-lang/rust/issues/99012
This reduces FormattingOptions from 6-7 machine words (384 bits on 64-bit platforms, 224 bits on 32-bit platforms) to just 64 bits (a single register on 64-bit platforms).
Before:
```rust
pub struct FormattingOptions {
flags: u32, // only 6 bits used
fill: char,
align: Option<Alignment>,
width: Option<usize>,
precision: Option<usize>,
}
```
After:
```rust
pub struct FormattingOptions {
/// Bits:
/// - 0-20: fill character (21 bits, a full `char`)
/// - 21: `+` flag
/// - 22: `-` flag
/// - 23: `#` flag
/// - 24: `0` flag
/// - 25: `x?` flag
/// - 26: `X?` flag
/// - 27: Width flag (if set, the width field below is used)
/// - 28: Precision flag (if set, the precision field below is used)
/// - 29-30: Alignment (0: Left, 1: Right, 2: Center, 3: Unknown)
/// - 31: Always set to 1
flags: u32,
/// Width if width flag above is set. Otherwise, always 0.
width: u16,
/// Precision if precision flag above is set. Otherwise, always 0.
precision: u16,
}
```
Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it
Fixes a regression, see issue below. This is a temporary fix, super let is the real solution.
Closes#138596
