Safer implementation of RepeatN
I've seen the "Use MaybeUninit for RepeatN" commit while reading This Week In Rust and immediately thought about something I've written some time ago - https://github.com/Soveu/repeat_finite/blob/master/src/lib.rs.
Using the fact, that `Option` will find niche in `(T, NonZeroUsize)`, we can construct something that has the same size as `(T, usize)` while completely getting rid of `MaybeUninit`.
This leaves only `unsafe` on `TrustedLen`, which is pretty neat.
Windows: Use anonymous pipes in Command
When setting `Stdio::pipe` on `Command` we want to create an anonymous pipe that can be used asynchronously (at least on our end). Usually we'd use [`CreatePipe`](https://learn.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-createpipe) to open anonymous pipes but unfortunately it opens pipes for synchronous access. The alternative is to use [`CreateNamedPipeW`](https://learn.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-createnamedpipew) which does allow asynchronous access but that requires giving a file name to the pipe. So we currently have this awful hack where we attempt to emulate anonymous pipes using `CreateNamedPipeW` by attempting to create a unique name and looping until we find one that doesn't already exist.
The better option is to use the lower level [`NtCreateNamedPipeFile`](https://learn.microsoft.com/en-us/windows/win32/devnotes/nt-create-named-pipe-file) (which is used internally by both `CreatePipe` and `CreateNamedPipeW`). This function wasn't documented until a few years ago but now that it is it's ok for us to use it.
try-job: *msvc*
try-job: *mingw*
Sized Hierarchy: Part I
This patch implements the non-const parts of rust-lang/rfcs#3729. It introduces two new traits to the standard library, `MetaSized` and `PointeeSized`. See the RFC for the rationale behind these traits and to discuss whether this change makes sense in the abstract.
These traits are unstable (as is their constness), so users cannot refer to them without opting-in to `feature(sized_hierarchy)`. These traits are not behind `cfg`s as this would make implementation unfeasible, there would simply be too many `cfg`s required to add the necessary bounds everywhere. So, like `Sized`, these traits are automatically implemented by the compiler.
RFC 3729 describes changes which are necessary to preserve backwards compatibility given the introduction of these traits, which are implemented and as follows:
- `?Sized` is rewritten as `MetaSized`
- `MetaSized` is added as a default supertrait for all traits w/out an explicit sizedness supertrait already.
There are no edition migrations implemented in this, as these are primarily required for the constness parts of the RFC and prior to stabilisation of this (and so will come in follow-up PRs alongside the const parts). All diagnostic output should remain the same (showing `?Sized` even if the compiler sees `MetaSized`) unless the `sized_hierarchy` feature is enabled.
Due to the use of unstable extern types in the standard library and rustc, some bounds in both projects have had to be relaxed already - this is unfortunate but unavoidable so that these extern types can continue to be used where they were before. Performing these relaxations in the standard library and rustc are desirable longer-term anyway, but some bounds are not as relaxed as they ideally would be due to the inability to relax `Deref::Target` (this will be investigated separately).
It is hoped that this is implemented such that it could be merged and these traits could exist "under the hood" without that being observable to the user (other than in any performance impact this has on the compiler, etc). Some details might leak through due to the standard library relaxations, but this has not been observed in test output.
**Notes:**
- Any commits starting with "upstream:" can be ignored, as these correspond to other upstream PRs that this is based on which have yet to be merged.
- This best reviewed commit-by-commit. I've attempted to make the implementation easy to follow and keep similar changes and test output updates together.
- Each commit has a short description describing its purpose.
- This patch is large but it's primarily in the test suite.
- I've worked on the performance of this patch and a few optimisations are implemented so that the performance impact is neutral-to-minor.
- `PointeeSized` is a different name from the RFC just to make it more obvious that it is different from `std::ptr::Pointee` but all the names are yet to be bikeshed anyway.
- `@nikomatsakis` has confirmed [that this can proceed as an experiment from the t-lang side](https://rust-lang.zulipchat.com/#narrow/channel/435869-project-goals/topic/SVE.20and.20SME.20on.20AArch64.20.28goals.23270.29/near/506196491)
- FCP in https://github.com/rust-lang/rust/pull/137944#issuecomment-2912207485Fixesrust-lang/rust#79409.
r? `@ghost` (I'll discuss this with relevant teams to find a reviewer)
std: refactor explanation of `NonNull`
Fixesrust-lang/rust#141933
I cut out the excessive explanation and used an example to explain how to maintain invariance, but I think what is quoted in the *rust reference* in the document needs to be added with a more layman's explanation and example.
(I'm not sure if I deleted too much)
r? `@workingjubilee`
As core uses an extern type (`ptr::VTable`), the default `?Sized` to
`MetaSized` migration isn't sufficient, and some code that previously
accepted `VTable` needs relaxed to continue to accept extern types.
Similarly, the compiler uses many extern types in `rustc_codegen_llvm`
and in the `rustc_middle::ty::List` implementation (`OpaqueListContents`)
some bounds must be relaxed to continue to accept these types.
Unfortunately, due to the current inability to relax `Deref::Target`,
some of the bounds in the standard library are forced to be stricter than
they ideally would be.
more information to Display implementation for BorrowError/BorrowMutError
- The BorrowError/BorrowMutError Debug implementations do not print
anything differently from what the derived implementation does, so we
don't need it.
- This change also adds the location field of
BorrowError/BorrowMutError to the the Display output when it is
present, rewords the error message, and uses the Display trait for
outputting the error message instead of Debug.
Introduce the `MetaSized` and `PointeeSized` traits as supertraits of
`Sized` and initially implement it on everything that currently
implements `Sized` to isolate any changes that simply adding the
traits introduces.
Add documentation for `PathBuf`'s `FromIterator` and `Extend` impls
I think it's not very obvious that `PathBuf`'s `Extend` and `FromIterator` impls work like `PathBuf::push`, so I think these should be documented.
I'm not very happy with the wording and examples, open to suggestions :)
float tests: deduplicate min, max, and rounding tests
Part of https://github.com/rust-lang/rust/issues/141726
Best reviewed commit-by-commit.
- Use `assert_biteq!` in the `mod.rs` tests. This requires some trickery to make shadowing macros with imports work.
- The min, max, minimum, maximum tests in `tests/floats/f*.rs` are entirely subsumed by what we already have in `tests/float/mod.rs`, so I just removed them.
- The rounding tests (floor etc) in `f*.rs` had more test points, so I copied them over. They didn't have `0.5` and `-0.5` though which seem like interesting points in particular regarding the sign of the resulting zero if that's what it sounds to, and they didn't max min/max/inf/nan tests, so this was really a merger of both tests.
r? ``@tgross35``
Unimplement unsized_locals
Implements https://github.com/rust-lang/compiler-team/issues/630
Tracking issue here: https://github.com/rust-lang/rust/issues/111942
Note that this just removes the feature, not the implementation, and does not touch `unsized_fn_params`. This is because it is required to support `Box<dyn FnOnce()>: FnOnce()`.
There may be more that should be removed (possibly in follow up prs)
- the `forget_unsized` function and `forget` intrinsic.
- the `unsized_locals` test directory; I've just fixed up the tests for now
- various codegen support for unsized values and allocas
cc ``@JakobDegen`` ``@oli-obk`` ``@Noratrieb`` ``@programmerjake`` ``@bjorn3``
``@rustbot`` label F-unsized_locals
Fixesrust-lang/rust#79409
Out-of-tree testing is broken with the most recent update from
rust-lang/rust because it makes `compiler-builtins` depend on `core` by
path, which isn't usually available. In order to enable testing outside
of rust-lang/rust, add a new crate `builtins-shim` that uses the same
source as `compiler-builtins` but drops the `core` dependency. This has
replaced `compiler-builtins` as the workspace member and entrypoint for
tests.
Remove "intermittent" wording from `ReadDir`
`ReadDir` claims that `next` will return an error "if there’s some sort of intermittent IO error during iteration". I'm really not sure what this was intended to mean but the implementations will simply return all OS errors encountered during iteration to the user. What else can they do?
This is technically a change in the documented API but seeing as how it doesn't bear any relationship with the implementation I don't think it needs a libs-api fcp.
doc: mention that intrinsics should not be called in user code
Intrinsic functions declared in `std::intrinsics` are an implementation detail and should not be called directly by the user. The compiler explicitly warns against their use in user code:
```
warning: the feature `core_intrinsics` is internal to the compiler or standard library
--> src/lib.rs:1:12
|
1 | #![feature(core_intrinsics)]
| ^^^^^^^^^^^^^^^
|
= note: using it is strongly discouraged
= note: `#[warn(internal_features)]` on by default
```
[**Playground link**]
This PR documents what the compiler warning says: these intrinsics should not be used in user code.
[**Playground link**]: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2024&gist=1c893b0698291f550bbdde0151fd221b
Use a consistent ordering for top-level manifest keys, and remove those
that are now redundant (`homapage` isn't supposed to be the same as
`repository`, and `documentation` automatically points to docs.rs now).
After adding tests, the current implementation for fminimum fails when
provided a negative zero and NaN as inputs:
---- math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f64 stdout ----
thread 'math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f64' panicked at libm/src/math/fminimum_fmaximum_num.rs:240:13:
fmaximum_num(-0x0p+0, NaN)
l: NaN (0x7ff8000000000000)
r: -0.0 (0x8000000000000000)
---- math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f32 stdout ----
thread 'math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f32' panicked at libm/src/math/fminimum_fmaximum_num.rs:240:13:
fmaximum_num(-0x0p+0, NaN)
l: NaN (0x7fc00000)
r: -0.0 (0x80000000)
Add more thorough spec tests for these functions and correct the
implementations.
Canonicalization is also moved to a trait method to centralize
documentation about what it does and doesn't do.
