rustc_allowed_through_unstable_modules: require deprecation message
This changes the `#[rustc_allowed_through_unstable_modules]` attribute so that a deprecation message (ideally directing people towards the stable path) is required.
Implement all mix/max functions in a (hopefully) more optimization amendable way
Previously the graph was like this:
```
min -> Ord::min -> min_by -> match on compare() (in these cases compare = Ord::cmp)
^
|
min_by_key
```
now it looks like this:
```
min -> Ord::min -> `<=` <- min_by_key
min_by -> `Ordering::is_le` of `compare()`
```
(`max*` and `minmax*` are the exact same, i.e. they also use `<=` and `is_le`)
I'm not sure how to test this, but it should probably be easier for the backend to optimize.
r? `@scottmcm`
cc https://github.com/rust-lang/rust/issues/115939#issuecomment-2622161134
Insert null checks for pointer dereferences when debug assertions are enabled
Similar to how the alignment is already checked, this adds a check
for null pointer dereferences in debug mode. It is implemented similarly
to the alignment check as a `MirPass`.
This inserts checks in the same places as the `CheckAlignment` pass and additionally
also inserts checks for `Borrows`, so code like
```rust
let ptr: *const u32 = std::ptr::null();
let val: &u32 = unsafe { &*ptr };
```
will have a check inserted on dereference. This is done because null references
are UB. The alignment check doesn't cover these places, because in `&(*ptr).field`,
the exact requirement is that the final reference must be aligned. This is something to
consider further enhancements of the alignment check.
For now this is implemented as a separate `MirPass`, to make it easy to disable
this check if necessary.
This is related to a 2025H1 project goal for better UB checks in debug
mode: https://github.com/rust-lang/rust-project-goals/pull/177.
r? `@saethlin`
Similar to how the alignment is already checked, this adds a check
for null pointer dereferences in debug mode. It is implemented similarly
to the alignment check as a MirPass.
This is related to a 2025H1 project goal for better UB checks in debug
mode: https://github.com/rust-lang/rust-project-goals/pull/177.
float::min/max: mention the non-determinism around signed 0
Turns out this can actually produce different results on different machines [in practice](https://github.com/rust-lang/rust/issues/83984#issuecomment-2623859230); that seems worth documenting. I assume LLVM will happily const-fold these operations so so there could be different results for the same input even on the same machine, depending on whether things get const-folded or not.
`@nikic` I remember there was an LLVM soundness fix regarding scalar evolution for loops that had to recognize certain operations as non-deterministic... it seems to me that pass would also have to avoid predicting the result of `llvm.{min,max}num`, for the same reason?
r? `@tgross35`
Cc `@rust-lang/libs-api`
If this lands we should also make Miri non-deterministic here.
Fixes https://github.com/rust-lang/rust/issues/83984
Stabilize `const_black_box`
This has been unstably const since #92226, but a tracking issue was never created. Per [discussion on Zulip][zulip], there should not be any blockers to making this const-stable. The function does not provide any functionality at compile time but does allow code reuse between const- and non-const functions, so stabilize it here.
[zulip]: https://rust-lang.zulipchat.com/#narrow/channel/146212-t-compiler.2Fconst-eval/topic/const_black_box
Remove minor future footgun in `impl Debug for MaybeUninit`
No longer breaks if `MaybeUninit` moves modules (technically it could break if `MaybeUninit` were renamed but realistically that will never happen)
Debug impl originally added in #133282
Add `AsyncFn*` to `core` prelude
In https://github.com/rust-lang/rust/pull/132611 these got added to the `std` prelude only, which looks like an oversight.
r? libs-api
cc `@compiler-errors`
Implement `int_from_ascii` (#134821)
Provides unstable `T::from_ascii()` and `T::from_ascii_radix()` for integer types `T`, as drafted in tracking issue #134821.
To deduplicate documentation without additional macros, implementations of `isize` and `usize` no longer delegate to equivalent integer types. After #132870 they are inlined anyway.
Cleanup docs for Allocator
This is an attempt to remove ungrammatical constructions and clean up the prose. I've sometimes had to try hard to understand what was being stated, so it is possible that I've misunderstood the original meaning. In particular, I did not see a difference between:
- the borrow-checker lifetime of the allocator type itself.
- as long as at least one of the allocator instance and all of its clones has not been dropped.
optimize slice::ptr_rotate for small rotates
r? `@scottmcm`
This swaps the positions and numberings of algorithms 1 and 2 in `slice::ptr_rotate`, and pulls the entire outer loop into algorithm 3 since it was redundant for the first two. Effectively, `ptr_rotate` now always does the `memcpy`+`memmove`+`memcpy` sequence if the shifts fit into the stack buffer.
With this change, an `IndexMap`-style `move_index` function is optimized correctly.
Assembly comparisons:
- `move_index`, before: https://godbolt.org/z/Kr616KnYM
- `move_index`, after: https://godbolt.org/z/1aoov6j8h
- the code from `#89714`, before: https://godbolt.org/z/Y4zaPxEG6
- the code from `#89714`, after: https://godbolt.org/z/1dPx83axc
related to #89714
some relevant discussion in https://internals.rust-lang.org/t/idea-shift-move-to-efficiently-move-elements-in-a-vec/22184
Behavior tests pass locally. I can't get any consistent microbenchmark results on my machine, but the assembly diffs look promising.
Put the core unit tests in a separate coretests package
Having standard library tests in the same package as a standard library crate has bad side effects. It causes the test to have a dependency on a locally built standard library crate, while also indirectly depending on it through libtest. Currently this works out fine in the context of rust's build system as both copies are identical, but for example in cg_clif's tests I've found it basically impossible to compile both copies with the exact same compiler flags and thus the two copies would cause lang item conflicts.
This PR moves the tests of libcore to a separate package which doesn't depend on libcore, thus preventing the duplicate crates even when compiler flags don't exactly match between building the sysroot (for libtest) and building the test itself. The rest of the standard library crates do still have this issue however.
compiler_fence: fix example
The old example was wrong, an acquire fence is required in the signal handler. To make the point more clear, I changed the "data" variable to use non-atomic accesses.
Fixes https://github.com/rust-lang/rust/issues/133014
Rollup of 7 pull requests
Successful merges:
- #133631 (Support QNX 7.1 with `io-sock`+libstd and QNX 8.0 (`no_std` only))
- #134358 (compiler: Set `target_abi = "ilp32e"` on all riscv32e targets)
- #135812 (Fix GDB `OsString` provider on Windows )
- #135842 (TRPL: more backward-compatible Edition changes)
- #135946 (Remove extra whitespace from rustdoc breadcrumbs for copypasting)
- #135953 (ci.py: check the return code in `run-local`)
- #136019 (Add an `unchecked_div` alias to the `Div<NonZero<_>>` impls)
r? `@ghost`
`@rustbot` modify labels: rollup
