Change swap_nonoverlapping from lang to library UB
The implementation of ptr::swap_nonoverlapping does not always escalate its safety contract to language UB, so it should be `check_library_ub`.
Fixes https://github.com/rust-lang/miri/issues/4188
Change the issue number for `likely_unlikely` and `cold_path`
These currently point to rust-lang/rust#26179, which is nearly a decade old and has a lot of outdated discussion. Move these features to a new tracking issue specifically for the recently added API.
New tracking issue: https://github.com/rust-lang/rust/issues/136873
This feature is intended to provide expensive but thorough help for
developers who have an unexpected `TypeId` value and need to determine
what type it actually is. It causes `impl Debug for TypeId` to print
the type name in addition to the opaque ID hash, and in order to do so,
adds a name field to `TypeId`. The cost of this is the increased size of
`TypeId` and the need to store type names in the binary; therefore, it
is an optional feature.
It may be enabled via `cargo -Zbuild-std -Zbuild-std-features=debug_typeid`.
(Note that `-Zbuild-std-features` disables default features which you
may wish to reenable in addition; see
<https://doc.rust-lang.org/cargo/reference/unstable.html#build-std-features>.)
Example usage and output:
```
fn main() {
use std::any::{Any, TypeId};
dbg!(TypeId::of::<usize>(), drop::<usize>.type_id());
}
```
```
TypeId::of::<usize>() = TypeId(0x763d199bccd319899208909ed1a860c6 = usize)
drop::<usize>.type_id() = TypeId(0xe6a34bd13f8c92dd47806da07b8cca9a = core::mem::drop<usize>)
```
Also added feature declarations for the existing `debug_refcell` feature
so it is usable from the `rust.std-features` option of `config.toml`.
This fixes the issues described in
https://github.com/rust-lang/rust/issues/136102. Primarily, this
resolves some issues with how the documentation for the prelude is
generated:
- It avoids showing "unstable" for macros in the prelude that are
actually stable.
- Avoids duplication of some pages due to the previous lack of
`doc(no_inline)`.
- Makes the different edition preludes consistent, and sets a pattern
that can be used by future editions.
We may need to rearrange these modules in the future if we decide to
remove anything from the prelude again. If we do, I think we should look
into a different solution that avoids the documentation problems.
Introduce CoercePointeeWellformed for coherence checks at typeck stage
Fix#135206
This is the first PR to introduce the "wellformedness" check for `derive(CoercePointee)`.
This patch introduces a new error code to cover all the prerequisites of the said macro. The checks that is enforced with this patch is whether the data is indeed `struct` and whether the layout is set to `repr(transparent)`.
A following series of patch will arrive later to address the following concern.
1. #135217 so that we would only admit one single coercion on one type parameter, and leave the rest for future consideration in tandem of development of other coercion rules.
1. Enforcement of data field requirements.
**An open question** is whether there is a good schema to encode the `#[pointee]` as well, so that we could also check if the `#[pointee]` type parameter is indeed `?Sized`.
``@rustbot`` label F-derive_coerce_pointee
Some miscellaneous edition-related library tweaks
Some library edition tweaks that can be done separately from upgrading the whole standard library to edition 2024 (which is blocked on getting the submodules upgraded, for example)
Update bootstrap compiler and rustfmt
The rustfmt version we previously used formats things differently from what the latest nightly rustfmt does. This causes issues for subtrees that get formatted both in-tree and in their own repo. Updating the rustfmt used in-tree solves those issues. Also bumped the bootstrap compiler as the stage0 update command always updates both at the same
time.
Rollup of 5 pull requests
Successful merges:
- #134679 (Windows: remove readonly files)
- #136213 (Allow Rust to use a number of libc filesystem calls)
- #136530 (Implement `x perf` directly in bootstrap)
- #136601 (Detect (non-raw) borrows of null ZST pointers in CheckNull)
- #136659 (Pick the max DWARF version when LTO'ing modules with different versions )
r? `@ghost`
`@rustbot` modify labels: rollup
Make `AsyncFnOnce`, `AsyncFnMut`, `AsyncFn` non-`#[fundamental]`
Address the issue #136723 on nightly (the issue will only *actually* be fixed with a beta backport).
Because the neutral element of `<fNN as iter::Sum>` was changed to
`neg_zero`, the documentation needed to be updated, as it was reporting
inadequate information about what should be expected from the return.
Co-authored-by: Jubilee <workingjubilee@gmail.com>
Using if ... with the intent to avoid branches can be surprising to readers and
carries the risk of turning into jumps/branches generated by some future
compiler version, breaking crucial optimizations.
This commit replaces their usage with the explicit and IR annotated
`bool::select_unpredictable`.
Rename `slice::take...` methods to `split_off...`
This rename was discussed and recommended in a recent t-libs meeting.
cc https://github.com/rust-lang/rust/issues/62280
There's an additional commit here which modifies internals of unstable `OneSidedRange` APIs in order to implement `split_off` methods in a panic-free way (remove `unreachable!()`) as recommended in https://github.com/rust-lang/rust/pull/88502/files#r760177240. I can split this out into a separate PR if needed.
implement inherent str constructors
implement #131114
this implements
- str::from_utf8
- str::from_utf8_mut
- str::from_utf8_unchecked
- str::from_utf8_unchecked_mut
i left `std::str::from_raw_parts` and `std::str::from_raw_parts_mut` out of this as those are unstable and were not mentioned by the tracking issue or the original pull request, but i can add those here as well.
i was also unsure of what to do with the `rustc_const_(un)stable` attributes: i removed the `#[rustc_const_stable]` attribute from `str::from_utf8`, `str::from_utf8_unchecked` and `str::from_utf8_unchecked_mut`, and left the`#[rust_const_unstable]` in `str::from_utf8_mut` (btw why is that one not const stable yet with #57349 merged?).
is there a way to redirect users to the stable `std::str::from_utf8` instead of only saying "hey this is unstable"?
for now i just removed the check for `str::from_utf8` in the test in `tests/ui/suggestions/suggest-std-when-using-type.rs`.
Mark `std::fmt::from_fn` as `#[must_use]`
While working on #135494 I managed to shoot my own foot a few times by forgetting to actually use the result of `fmt::from_fn`, so I think a `#[must_use]` could be appropriate!
Didn't have a good message to put in the attr so left it blank, still unstable so we can come back to it I guess?
cc #117729 (and a huge +1 for getting it stabilized, it's very useful IMHO)
#[contracts::requires(...)] + #[contracts::ensures(...)]
cc https://github.com/rust-lang/rust/issues/128044
Updated contract support: attribute syntax for preconditions and postconditions, implemented via a series of desugarings that culminates in:
1. a compile-time flag (`-Z contract-checks`) that, similar to `-Z ub-checks`, attempts to ensure that the decision of enabling/disabling contract checks is delayed until the end user program is compiled,
2. invocations of lang-items that handle invoking the precondition, building a checker for the post-condition, and invoking that post-condition checker at the return sites for the function, and
3. intrinsics for the actual evaluation of pre- and post-condition predicates that third-party verification tools can intercept and reinterpret for their own purposes (e.g. creating shims of behavior that abstract away the function body and replace it solely with the pre- and post-conditions).
Known issues:
* My original intent, as described in the MCP (https://github.com/rust-lang/compiler-team/issues/759) was to have a rustc-prefixed attribute namespace (like rustc_contracts::requires). But I could not get things working when I tried to do rewriting via a rustc-prefixed builtin attribute-macro. So for now it is called `contracts::requires`.
* Our attribute macro machinery does not provide direct support for attribute arguments that are parsed like rust expressions. I spent some time trying to add that (e.g. something that would parse the attribute arguments as an AST while treating the remainder of the items as a token-tree), but its too big a lift for me to undertake. So instead I hacked in something approximating that goal, by semi-trivially desugaring the token-tree attribute contents into internal AST constucts. This may be too fragile for the long-term.
* (In particular, it *definitely* breaks when you try to add a contract to a function like this: `fn foo1(x: i32) -> S<{ 23 }> { ... }`, because its token-tree based search for where to inject the internal AST constructs cannot immediately see that the `{ 23 }` is within a generics list. I think we can live for this for the short-term, i.e. land the work, and continue working on it while in parallel adding a new attribute variant that takes a token-tree attribute alongside an AST annotation, which would completely resolve the issue here.)
* the *intent* of `-Z contract-checks` is that it behaves like `-Z ub-checks`, in that we do not prematurely commit to including or excluding the contract evaluation in upstream crates (most notably, `core` and `std`). But the current test suite does not actually *check* that this is the case. Ideally the test suite would be extended with a multi-crate test that explores the matrix of enabling/disabling contracts on both the upstream lib and final ("leaf") bin crates.
Rollup of 5 pull requests
Successful merges:
- #134777 (Enable more tests on Windows)
- #135621 (Move some std tests to integration tests)
- #135844 ( Add new tool for dumping feature status based on tidy )
- #136167 (Implement unstable `new_range` feature)
- #136334 (Extract `core::ffi` primitives to a separate (internal) module)
Failed merges:
- #136201 (Removed dependency on the field-offset crate, alternate approach)
r? `@ghost`
`@rustbot` modify labels: rollup
Add `cast_signed` and `cast_unsigned` methods for `NonZero` types
Requested in https://github.com/rust-lang/rust/issues/125882 .
Note that this keeps the same names as the methods currently present on other
integer types. If we want to rename them, we can rename them all at the same
time.
Extract `core::ffi` primitives to a separate (internal) module
### Introduce library/core/src/ffi/primitives.rs
The regex preprocessing for PR #133944 would be more robust if the relevant types from core/src/ffi/mod.rs were first moved to library/core/src/ffi/primitives.rs, then there isn't a need to deal with traits / c_str / va_list / whatever might wind up in that module in the future
r? `@tgross35`
Implement unstable `new_range` feature
Switches `a..b`, `a..`, and `a..=b` to resolve to the new range types.
For rust-lang/rfcs#3550
Tracking issue #123741
also adds the re-export that was missed in the original implementation of `new_range_api`
Display of integers without raw pointers and without overflowing_literals
The benchmarks as is measure formatting speed of literals. The first commit `black_box`-es input to simulate runtime speed instead.
The second commit replaces `unsafe` pointer optimizations with plain array indices. The performance is equivalent on Apple M1. Needs peer review on Intel.
Happy to do the 128-bit version too if such change is welcome.
This has now been approved as a language feature and no longer needs
a `rustc_` prefix.
Also change the `contracts` feature to be marked as incomplete and
`contracts_internals` as internal.
1. Document the new intrinsics.
2. Make the intrinsics actually check the contract if enabled, and
remove `contract::check_requires` function.
3. Use panic with no unwind in case contract is using to check for
safety, we probably don't want to unwind. Following the same
reasoning as UB checks.
The extended syntax for function signature that includes contract clauses
should never be user exposed versus the interface we want to ship
externally eventually.
includes post-developed commit: do not suggest internal-only keywords as corrections to parse failures.
includes post-developed commit: removed tabs that creeped in into rustfmt tool source code.
includes post-developed commit, placating rustfmt self dogfooding.
includes post-developed commit: add backquotes to prevent markdown checking from trying to treat an attr as a markdown hyperlink/
includes post-developed commit: fix lowering to keep contracts from being erroneously inherited by nested bodies (like closures).
Rebase Conflicts:
- compiler/rustc_parse/src/parser/diagnostics.rs
- compiler/rustc_parse/src/parser/item.rs
- compiler/rustc_span/src/hygiene.rs
Remove contracts keywords from diagnostic messages
There was a macro parameter giving signed impls access to the
corresponding unsigned type, but not the other way around.
This will allow implementing methods converting in both directions.
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.
* Renames the methods:
* `get_many_mut` -> `get_disjoint_mut`
* `get_many_unchecked_mut` -> `get_disjoint_unchecked_mut`
* Does not rename the feature flag: `get_many_mut`
* Marks the feature as stable
* Renames some helper stuff:
* `GetManyMutError` -> `GetDisjointMutError`
* `GetManyMutIndex` -> `GetDisjointMutIndex`
* `get_many_mut_helpers` -> `get_disjoint_mut_helpers`
* `get_many_check_valid` -> `get_disjoint_check_valid`
This only touches slice methods.
HashMap's methods and feature gates are not renamed here
(nor are they stabilized).
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
Update emscripten std tests
This disables a bunch of emscripten tests that test things emscripten doesn't support and re-enables a whole bunch of tests which now work just fine on emscripten.
Tested with `EMCC_CFLAGS="-s MAXIMUM_MEMORY=2GB" ./x.py test library/ --target wasm32-unknown-emscripten`.
Fix `FormattingOptions` instantiation with `Default`
The `fill` value by default should be set to `' '` (space), but the current implementation uses `#[derive(Default)]` which sets it to `\0`.
Note that `FormattingOptions` is being released as part of 1.85 (unstable) - so this might warrant a backport to that branch.
Tracking issue: https://github.com/rust-lang/rust/issues/118117
Follow up from https://github.com/rust-lang/rust/pull/118159
CC: ``@EliasHolzmann`` ``@programmerjake``
r? ``@m-ou-se``
Add memory layout documentation to generic NonZero<T>
The documentation I've added is based on the same Layout documentation that appears on the other `NonZero*` types. For example see [the Layout docs on `NonZeroI8`](https://doc.rust-lang.org/std/num/type.NonZeroI8.html#layout-1).
remove pointless allowed_through_unstable_modules on TryFromSliceError
This got added in https://github.com/rust-lang/rust/pull/132482 but the PR does not explain why. `@lukas-code` do you still remember? Also Cc `@Noratrieb` as reviewer of that PR.
If I understand the issue description correctly, all paths under which this type is exported are stable now: `core::array::TryFromSliceError` and `std::array::TryFromSliceError`. If that is the case, we shouldn't have the attribute; it's a terrible hack that should only be used when needed to maintain backward compatibility. Getting some historic information right is IMO *not* sufficient justification to risk accidentally exposing this type via more unstable paths today or in the future.
Implement `ByteStr` and `ByteString` types
Approved ACP: https://github.com/rust-lang/libs-team/issues/502
Tracking issue: https://github.com/rust-lang/rust/issues/134915
These types represent human-readable strings that are conventionally,
but not always, UTF-8. The `Debug` impl prints non-UTF-8 bytes using
escape sequences, and the `Display` impl uses the Unicode replacement
character.
This is a minimal implementation of these types and associated trait
impls. It does not add any helper methods to other types such as `[u8]`
or `Vec<u8>`.
I've omitted a few implementations of `AsRef`, `AsMut`, and `Borrow`,
when those would be the second implementation for a type (counting the
`T` impl), to avoid potential inference failures. We can attempt to add
more impls later in standalone commits, and run them through crater.
In addition to the `bstr` feature, I've added a `bstr_internals` feature
for APIs provided by `core` for use by `alloc` but not currently
intended for stabilization.
This API and its implementation are based *heavily* on the `bstr` crate
by Andrew Gallant (`@BurntSushi).`
r? `@BurntSushi`
Add an example of using `carrying_mul_add` to write wider multiplication
Just the basic quadratic version that you wouldn't actually use for really-big integers, but it's nice and short so is useful as for a demonstration of why you might find `carrying_mul_add` useful :)
cc #85532 ``````@clarfonthey``````
