formatting_options: fix alternate docs 0b/0o mixup
The descriptions of the alternate forms of Octal and Binary were swapped in the doc comment for FormattingOptions::alternate().
Introduce CoerceShared lang item and trait, and basic Reborrow tests
Part of rust-lang/rust#145612: This introduces the `CoerceShared` trait which is the `Reborrow` equivalent of a `&mut T` -> `&T` coercion. The trait has a `Target` GAT which makes this (currently) unique in the `core/src/marker.rs`; I'm not sure if this can be considered problematic. Maybe this is not the way such things should be done at the marker trait level? Or maybe it is fine.
Improtantly, this PR introduces a battery of basic `Reborrow` and `CoerceShared` tests. These test the very basics of the feature; custom marker types intended to have exclusive semantics (`Custom<'a>(PhantomData<&'a mut ()>)`), custom exclusive reference wrappers, and standard library exclusive reference wrappers (`Pin<&mut T>` and `Option<&mut T>`). None of these of course work since the implementation for `Reborrow` and `CoerceShared` is entirely missing, but this is the first step towards making these work.
Future PRs will introduce more tests, such as "recursive" reborrowing (ie. reborrowing structs that contain multiple reborrowable fields) and checks around the lifetime semantics of reborrowing ie. that a reborrow produces a new type with the same lifetime as the original.
Add doc for `NonZero*` const creation
I ran into trouble using `NonZero*` values because I didn’t see any clear way to create them at compile time. At first I ended up using `NonZero*::new_unchecked` a lot, until I realized that `Option::unwrap` and `Option::expect` are `const` and can be used in a `const` context. With that, you can create non-zero values at compile time safely, without touching `unsafe`. This wasn’t obvious to me and my peers who’ve been using Rust for a while, so I thought adding a note to the docs would make it easier for others to discover.
If this should be worded differently or placed in another location, we can do that. I just want to make this more obvious.
Rollup of 7 pull requests
Successful merges:
- rust-lang/rust#146556 (Fix duration_since panic on unix when std is built with integer overflow checks)
- rust-lang/rust#146679 (Clarify Display for error should not include source)
- rust-lang/rust#146753 (Improve the pretty print of UnstableFeature clause)
- rust-lang/rust#146894 (Improve derive suggestion of const param)
- rust-lang/rust#146950 (core: simplify `CStr::default()`)
- rust-lang/rust#146958 (Fix infinite recursion in Path::eq with String)
- rust-lang/rust#146971 (fix ICE in writeback due to bound regions)
r? `@ghost`
`@rustbot` modify labels: rollup
Make missed precondition-free float intrinsics safe
So, in my defence, these were both separated out from the other intrinsics in the file *and* had a different safety comment in the stable versions, so, I didn't notice them before. But, in my offence, the entire reason I did the previous PR was because I was using them for SIMD intrinsic fallbacks, and `fabs` is needed for those too, so, I don't really have an excuse.
Extra follow-up to rust-lang/rust#146683.
r? ```@RalfJung``` who reviewed the previous one
These don't appear to be used anywhere outside of the standard locations, at least.
Fix uses of "adaptor"
These docs are in en_US, so "adapter" is the correct spelling (and indeed used in the next line.)
A second commit comes along for the ride to fix other instances in non-rustdoc comments.
Add panic=immediate-abort
MCP: https://github.com/rust-lang/compiler-team/issues/909
This adds a new panic strategy, `-Cpanic=immediate-abort`. This panic strategy essentially just codifies use of `-Zbuild-std-features=panic_immediate_abort`. This PR is intended to just set up infrastructure, and while it will change how the compiler is invoked for users of the feature, there should be no other impacts.
In many parts of the compiler, `PanicStrategy::ImmediateAbort` behaves just like `PanicStrategy::Abort`, because actually most parts of the compiler just mean to ask "can this unwind?" so I've added a helper function so we can say `sess.panic_strategy().unwinds()`.
The panic and unwind strategies have some level of compatibility, which mostly means that we can pre-compile the sysroot with unwinding panics then the sysroot can be linked with aborting panics later. The immediate-abort strategy is all-or-nothing, enforced by `compiler/rustc_metadata/src/dependency_format.rs` and this is tested for in `tests/ui/panic-runtime/`. We could _technically_ be more compatible with the other panic strategies, but immediately-aborting panics primarily exist for users who want to eliminate all the code size responsible for the panic runtime. I'm open to other use cases if people want to present them, but not right now. This PR is already large.
`-Cpanic=immediate-abort` sets both `cfg(panic = "immediate-abort")` _and_ `cfg(panic = "abort")`. bjorn3 pointed out that people may be checking for the abort cfg to ask if panics will unwind, and also the sysroot feature this is replacing used to require `-Cpanic=abort` so this seems like a good back-compat step. At least for the moment. Unclear if this is a good idea indefinitely. I can imagine this being confusing.
The changes to the standard library attributes are purely mechanical. Apart from that, I removed an `unsafe` we haven't needed for a while since the `abort` intrinsic became safe, and I've added a helpful diagnostic for people trying to use the old feature.
To test that `-Cpanic=immediate-abort` conflicts with other panic strategies, I've beefed up the core-stubs infrastructure a bit. There is now a separate attribute to set flags on it.
I've added a test that this produces the desired codegen, called `tests/run-make-cargo/panic-immediate-abort-codegen/` and also a separate run-make-cargo test that checks that we can build a binary.
Mark float intrinsics with no preconditions as safe
Note: for ease of reviewing, the list of safe intrinsics is sorted in the first commit, and then safe intrinsics are added in the second commit.
All *recently added* float intrinsics have been correctly marked as safe to call due to the fact that they have no preconditions. This adds the remaining float intrinsics which are safe to call to the safe intrinsic list, and removes the unsafe blocks around their calls.
---
Side note: this may want a try run before being added to the queue, since I'm not sure if there's any tier-2 code that uses these intrinsics that might not be tested on the usual PR flow. We've already uncovered a few places in subtrees that do this, and it's worth double-checking before clogging up the queue.
add `[const] PartialEq` bound to `PartialOrd`
This change is included for discussion purposes.
The PartialOrd bound on PartialEq is not strictly necessary. It is, rather, logical: anything which is orderable should by definition have equality. Is the same true for constness? Should every type which is const orderable also have const equality?
This change is included for discussion purposes.
The PartialOrd bound on PartialEq is not strictly necessary. It
is, rather, logical: anything which is orderable should by
definition have equality. Is the same true for constness? Should
every type which is const orderable also have const equality?
Remove Rvalue::Len again.
Now that we have `RawPtrKind::FakeForPtrMetadata`, we can reimplement `Rvalue::Len` using `PtrMetadata(&raw const (fake) place)`.
r? ``@scottmcm``
initial implementation of the darwin_objc unstable feature
Tracking issue: https://github.com/rust-lang/rust/issues/145496
This feature makes it possible to reference Objective-C classes and selectors using the same ABI used by native Objective-C on Apple/Darwin platforms. Without it, Rust code interacting with Objective-C must resort to loading classes and selectors using costly string-based lookups at runtime. With it, these references can be loaded efficiently at dynamic load time.
r? ```@tmandry```
try-job: `*apple*`
try-job: `x86_64-gnu-nopt`
Matthias Krüger