make Cell unstably const
Now that we can do interior mutability in `const`, most of the Cell API can be `const fn`. :) The main exception is `set`, because it drops the old value. So from const context one has to use `replace`, which delegates the responsibility for dropping to the caller.
Tracking issue: https://github.com/rust-lang/rust/issues/131283
`as_array_of_cells` is itself still unstable to I added the const-ness to the feature gate for that function and not to `const_cell`, Cc #88248.
r? libs-api
std: replace `LazyBox` with `OnceBox`
This PR replaces the `LazyBox` wrapper used to allocate the pthread primitives with `OnceBox`, which has a more familiar API mirroring that of `OnceLock`. This cleans up the code in preparation for larger changes like #128184 (from which this PR was split) and allows some neat optimizations, like avoid an acquire-load of the allocation pointer in `Mutex::unlock`, where the initialization of the allocation must have already been observed.
Additionally, I've gotten rid of the TEEOS `Condvar` code, it's just a duplicate of the pthread one anyway and I didn't want to repeat myself.
Stabilize the `map`/`value` methods on `ControlFlow`
And fix the stability attribute on the `pub use` in `core::ops`.
libs-api in https://github.com/rust-lang/rust/issues/75744#issuecomment-2231214910 seemed reasonably happy with naming for these, so let's try for an FCP.
Summary:
```rust
impl<B, C> ControlFlow<B, C> {
pub fn break_value(self) -> Option<B>;
pub fn map_break<T>(self, f: impl FnOnce(B) -> T) -> ControlFlow<T, C>;
pub fn continue_value(self) -> Option<C>;
pub fn map_continue<T>(self, f: impl FnOnce(C) -> T) -> ControlFlow<B, T>;
}
```
Resolves#75744
``@rustbot`` label +needs-fcp +t-libs-api -t-libs
---
Aside, in case it keeps someone else from going down the same dead end: I looked at the `{break,continue}_value` methods and tried to make them `const` as part of this, but that's disallowed because of not having `const Drop`, so put it back to not even unstably-const.
Avoid emptiness check in `PeekMut::pop`
This PR avoids an unnecessary emptiness check in `PeekMut::pop` by replacing `Option::unwrap` with `Option::unwrap_unchecked`.
Add `get_line` confusable to `Stdin::read_line()`
This pull request resolves https://github.com/rust-lang/rust/issues/131091
---
I've updated tests for `tests/ui/attributes/rustc_confusables_std_cases` in order to verify this change is working as intended.
Before I submitted this pull request, I had a pull request to my local fork. If you're interested in seeing the conversation on that PR, go to https://github.com/JakenHerman/rust/pull/1.
---
**Testing**:
Run `./x.py test tests/ui/attributes/rustc_confusables_std_cases.rs`
impl `Default` for `HashMap`/`HashSet` iterators that don't already have it
This is a follow-up to #128261 that isn't included in that PR because it depends on:
* [x] rust-lang/hashbrown#542 (`Default`)
* [x] `hashbrown` release containing above
It also wasn't included in #128261 initially and should have its own FCP, since these are also insta-stable.
Changes added:
* `Default for hash_map::{Iter, IterMut, IntoIter, IntoKeys, IntoValues, Keys, Values, ValuesMut}`
* `Default for hash_set::{Iter, IntoIter}`
Changes that were added before FCP, but are being deferred to later:
* `Clone for hash_map::{IntoIter, IntoKeys, IntoValues} where K: Clone, V: Clone`
* `Clone for hash_set::IntoIter where K: Clone`
std: make `thread::current` available in all `thread_local!` destructors
... and thereby allow the panic runtime to always print the right thread name.
This works by modifying the TLS destructor system to schedule a runtime cleanup function after all other TLS destructors registered by `std` have run. Unfortunately, this doesn't affect foreign TLS destructors, `thread::current` will still panic there.
Additionally, the thread ID returned by `current_id` will now always be available, even inside the global allocator, and will not change during the lifetime of one thread (this was previously the case with key-based TLS).
The mechanisms I added for this (`local_pointer` and `thread_cleanup`) will also allow finally fixing #111272 by moving the signal stack to a similar runtime-cleanup TLS variable.
Update hashbrown to 0.15 and adjust some methods
This PR updates `hashbrown` to 0.15 in the standard library and adjust some methods as well as removing some as they no longer exists in Hashbrown it-self.
- `HashMap::get_many_mut` change API to return array-of-Option
- `HashMap::{replace_entry, replace_key}` are removed, FCP close [already finished](https://github.com/rust-lang/rust/issues/44286#issuecomment-2293825619)
- `HashSet::get_or_insert_owned` is removed as it no longer exists in hashbrown
Closes https://github.com/rust-lang/rust/issues/44286
r? `@Amanieu`
mpmc doctest: make sure main thread waits for child threads
Currently, chances are half the test is not executed because the main thread exits while the other threads are still working.
Cc `@obeis` `@Amanieu`
Add `[Option<T>; N]::transpose`
This PR as a new unstable libs API, `[Option<T>; N]::transpose`, which permits going from `[Option<T>; N]` to `Option<[T; N]>`.
This new API doesn't have an ACP as it was directly asked by T-libs-api in https://github.com/rust-lang/rust/issues/97601#issuecomment-2372109119:
> [..] but it'd be trivial to provide a helper method `.transpose()` that turns array-of-Option into Option-of-array (**and we think that method should exist**; it already does for array-of-MaybeUninit).
r? libs
This PR replaces the `LazyBox` wrapper used to allocate the pthread primitives with `OnceBox`, which has a more familiar API mirroring that of `OnceLock`. This cleans up the code in preparation for larger changes like #128184 (from which this PR was split) and allows some neat optimizations, like avoid an acquire-load of the allocation pointer in `Mutex::unlock`, where the initialization of the allocation must have already been observed.
Additionally, I've gotten rid of the TEEOS `Condvar` code, it's just a duplicate of the pthread one anyway and I didn't want to repeat myself.
Update Unicode escapes in `/library/core/src/char/methods.rs`
`char::MAX` is inconsistent on how Unicode escapes should be formatted. This PR resolves that.
ptr::add/sub: do not claim equivalence with `offset(c as isize)`
In https://github.com/rust-lang/rust/pull/110837, the `offset` intrinsic got changed to also allow a `usize` offset parameter. The intention is that this will do an unsigned multiplication with the size, and we have UB if that overflows -- and we also have UB if the result is larger than `usize::MAX`, i.e., if a subsequent cast to `isize` would wrap. ~~The LLVM backend sets some attributes accordingly.~~
This updates the docs for `add`/`sub` to match that intent, in preparation for adjusting codegen to exploit this UB. We use this opportunity to clarify what the exact requirements are: we compute the offset using mathematical multiplication (so it's no problem to have an `isize * usize` multiplication, we just multiply integers), and the result must fit in an `isize`.
Cc `@rust-lang/opsem` `@nikic`
https://github.com/rust-lang/rust/pull/130239 updates Miri to detect this UB.
`sub` still has some cases of UB not reflected in the underlying intrinsic semantics (and Miri does not catch): when we subtract `usize::MAX`, then after casting to `isize` that's just `-1` so we end up adding one unit without noticing any UB, but actually the offset we gave does not fit in an `isize`. Miri will currently still not complain for such cases:
```rust
fn main() {
let x = &[0i32; 2];
let x = x.as_ptr();
// This should be UB, we are subtracting way too much.
unsafe { x.sub(usize::MAX).read() };
}
```
However, the LLVM IR we generate here also is UB-free. This is "just" library UB but not language UB.
Cc `@saethlin;` might be worth adding precondition checks against overflow on `offset`/`add`/`sub`?
Fixes https://github.com/rust-lang/rust/issues/130211
Rollup of 5 pull requests
Successful merges:
- #130630 (Support clobber_abi and vector/access registers (clobber-only) in s390x inline assembly)
- #131042 (Instantiate binders in `supertrait_vtable_slot`)
- #131079 (Update wasm-component-ld to 0.5.9)
- #131085 (make test_lots_of_insertions test take less long in Miri)
- #131088 (add fixme to remove LLVM_ENABLE_TERMINFO when minimal llvm version is 19)
r? `@ghost`
`@rustbot` modify labels: rollup
make test_lots_of_insertions test take less long in Miri
This is by far the slowest `std` test in Miri, taking >2min in https://github.com/rust-lang/miri-test-libstd CI. So let's make this `count` smaller. The runtime should be quadratic in `count` so reducing it to around 2/3 of it's previous value should cut the total time down to less than half -- making it still the slowest test, but by less of a margin. (And this way we still insert >64 elements into the HashMap, in case that power of 2 matters.)
There is a MinGW ABI bug that prevents `f16` and `f128` from being
usable on `windows-gnu` targets. This does not affect MSVC; however, we
have `f16` and `f128` tests disabled on all Windows targets.
Update the gating to only affect `windows-gnu`, which means `f16` tests
will be enabled. There is no effect for `f128` since the default
fallback is `false`.
