Rollup of 3 pull requests
Successful merges:
- #112260 (Improve document of `unsafe_code` lint)
- #112429 ([rustdoc] List matching impls on type aliases)
- #112442 (Deduplicate identical region constraints in new solver)
r? `@ghost`
`@rustbot` modify labels: rollup
Uplift `clippy::undropped_manually_drops` lint
This PR aims at uplifting the `clippy::undropped_manually_drops` lint.
## `undropped_manually_drops`
(warn-by-default)
The `undropped_manually_drops` lint check for calls to `std::mem::drop` with a value of `std::mem::ManuallyDrop` which doesn't drop.
### Example
```rust
struct S;
drop(std::mem::ManuallyDrop::new(S));
```
### Explanation
`ManuallyDrop` does not drop it's inner value so calling `std::mem::drop` will not drop the inner value of the `ManuallyDrop` either.
-----
Mostly followed the instructions for uplifting an clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
`@rustbot` label: +I-lang-nominated
r? compiler
-----
For Clippy:
changelog: Moves: Uplifted `clippy::undropped_manually_drops` into rustc
Add `task::Waker::noop`
I have found myself reimplementing this function many times when I need a `Context` but don't have a runtime or `futures` to hand.
Prior art: [`futures::task::noop_waker`](https://docs.rs/futures/0.3/futures/task/fn.noop_waker.html) and [`futures::task::noop_waker_ref`](https://docs.rs/futures/0.3/futures/task/fn.noop_waker_ref.html)
Tracking issue: https://github.com/rust-lang/rust/issues/98286
Unresolved questions:
1. Should we also add `RawWaker::noop()`? (I don't think so, I can't think of a use case for it)
2. Should we also add `Context::noop()`? Depending on the future direction `Context` goes a "noop context" might not even make sense in future.
3. Should it be an associated constant instead? That would allow for `let cx = &mut Context::from_waker(&Waker::NOOP);` to work on one line which is pretty nice. I don't really know what the guideline is here.
r? rust-lang/libs-api `@rustbot` label +T-libs-api -T-libs
- Switch TypeId to 128 bits
- Hack around the fact that tracing-subscriber dislikes how TypeId is hashed
- Remove lowering of type_id128 from rustc_codegen_llvm
- Remove unnecessary `type_id128` intrinsic (just change return type of `type_id`)
- Only hash the lower 64 bits of the TypeId
- Reword comment
add `#[doc(alias="flatmap")]` to `Option::and_then`
I keep forgetting that rust calls this `and_then` and trying to search for `flatmap`. `and_then`'s docs even mention "Some languages call this operation flatmap", but it doesn't show up as a result in the search at `https://doc.rust-lang.org/std/?search=flatmap`
Option::map_or_else: Show an example of integrating with Result
Moving this from https://github.com/rust-lang/libs-team/issues/59 where an API addition was rejected. But I think it's valuable to add this example to the documentation at least.
remove reference to Into in ? operator core/std docs, fix#111655
remove the text stating that `?` uses `Into::into` and add text stating it uses `From::from` instead. This closes#111655.
Uplift `clippy::cast_ref_to_mut` lint
This PR aims at uplifting the `clippy::cast_ref_to_mut` lint into rustc.
## `cast_ref_to_mut`
(deny-by-default)
The `cast_ref_to_mut` lint checks for casts of `&T` to `&mut T` without using interior mutability.
### Example
```rust,compile_fail
fn x(r: &i32) {
unsafe {
*(r as *const i32 as *mut i32) += 1;
}
}
```
### Explanation
Casting `&T` to `&mut T` without interior mutability is undefined behavior, as it's a violation of Rust reference aliasing requirements.
-----
Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
`@rustbot` label: +I-lang-nominated
r? compiler
-----
For Clippy:
changelog: Moves: Uplifted `clippy::cast_ref_to_mut` into rustc
Uplift `clippy::invalid_utf8_in_unchecked` lint
This PR aims at uplifting the `clippy::invalid_utf8_in_unchecked` lint into two lints.
## `invalid_from_utf8_unchecked`
(deny-by-default)
The `invalid_from_utf8_unchecked` lint checks for calls to `std::str::from_utf8_unchecked` and `std::str::from_utf8_unchecked_mut` with an invalid UTF-8 literal.
### Example
```rust
unsafe {
std::str::from_utf8_unchecked(b"cl\x82ippy");
}
```
### Explanation
Creating such a `str` would result in undefined behavior as per documentation for `std::str::from_utf8_unchecked` and `std::str::from_utf8_unchecked_mut`.
## `invalid_from_utf8`
(warn-by-default)
The `invalid_from_utf8` lint checks for calls to `std::str::from_utf8` and `std::str::from_utf8_mut` with an invalid UTF-8 literal.
### Example
```rust
std::str::from_utf8(b"ru\x82st");
```
### Explanation
Trying to create such a `str` would always return an error as per documentation for `std::str::from_utf8` and `std::str::from_utf8_mut`.
-----
Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
````@rustbot```` label: +I-lang-nominated
r? compiler
-----
For Clippy:
changelog: Moves: Uplifted `clippy::invalid_utf8_in_unchecked` into rustc
`[T; N]::zip` is "eager" but most zips are mapped.
This causes poor optimization in generated code.
This is a fundamental design issue and "zip" is
"prime real estate" in terms of function names,
so let's free it up again.
All the implementations of the trait already are `Copy`, and this seems to be enough to simplify the implementations enough to make the MIR inliner willing to inline basics like `Range::next`.
Fix docs for `alloc::realloc`
Fixes#108546.
Corrects the docs for `alloc::realloc` to bring the safety constraints into line with `Layout::from_size_align_unchecked`'s constraints.
Rollup of 6 pull requests
Successful merges:
- #111936 (Include test suite metadata in the build metrics)
- #111952 (Remove DesugaringKind::Replace.)
- #111966 (Add #[inline] to array TryFrom impls)
- #111983 (Perform MIR type ops locally in new solver)
- #111997 (Fix re-export of doc hidden macro not showing up)
- #112014 (rustdoc: get unnormalized link destination for suggestions)
r? `@ghost`
`@rustbot` modify labels: rollup
Add #[inline] to array TryFrom impls
I was looking into https://github.com/rust-lang/rust/issues/111959 and I realized we don't have these. They seem like an uncontroversial addition.
IMO this PR does not fix that issue. I think the bad codegen is being caused by some underlying deeper problem but this change might cause the MIR inliner to paper over it in this specific case.
r? `@thomcc`
Update current implementation comments for `select_nth_unstable`
This more accurately reflects the actual implementation, as it hasn't been a simple quickselect since #106997. While it does say that the current implementation always runs in O(n), I don't think it should require an FCP as it doesn't guarantee linearity in general and only points out that the current implementation is in fact linear.
r? `@Amanieu`
Add Median of Medians fallback to introselect
Fixes#102451.
This PR is a follow up to #106997. It adds a Fast Deterministic Selection implementation as a fallback to the introselect algorithm used by `select_nth_unstable`. This allows it to guarantee O(n) worst case running time, while maintaining good performance in all cases.
This would fix#102451, which was opened because the `select_nth_unstable` docs falsely claimed that it had O(n) worst case performance, even though it was actually quadratic in the worst case. #106997 improved the worst case complexity to O(n log n) by using heapsort as a fallback, and this PR further improves it to O(n) (this would also make #106933 unnecessary).
It also improves the actual runtime if the fallback gets called: Using a pathological input of size `1 << 19` (see the playground link in #102451), calculating the median is roughly 3x faster using fast deterministic selection as a fallback than it is using heapsort.
The downside to this is less code reuse between the sorting and selection algorithms, but I don't think it's that bad. The additional algorithms are ~250 LOC with no `unsafe` blocks (I tried using unsafe to avoid bounds checks but it didn't noticeably improve the performance).
I also let it fuzz for a while against the current `select_nth_unstable` implementation to ensure correctness, and it seems to still fulfill all the necessary postconditions.
cc `@scottmcm` who reviewed #106997
[rustc_ty_utils] Treat `drop_in_place`'s *mut argument like &mut when adding LLVM attributes
This resurrects PR #103614, which has sat idle for a while.
This could probably use a new perf run, since we're on a new LLVM version now.
r? `@oli-obk`
cc `@RalfJung`
---
LLVM can make use of the `noalias` parameter attribute on the parameter to `drop_in_place` in areas like argument promotion. Because the Rust compiler fully controls the code for `drop_in_place`, it can soundly deduce parameter attributes on it.
In #103957, Miri was changed to retag `drop_in_place`'s argument as if it was `&mut`, matching this change.
Give better error when collecting into `&[T]`
The detection of slice reference of `{integral}` in `rustc_on_unimplemented` is hacky, but a proper solution requires changing `FmtPrinter` to add a parameter to print integers as `{integral}` and I didn't want to change it just for `rustc_on_unimplemented`. I can do that if requested, though.
I'm open to better wording; this is the best I could come up with.
Mark internal functions and traits unsafe to reflect preconditions
No semantics are changed in this PR; I only mark some functions and and a trait `unsafe` which already had implicit preconditions. Although it seems somewhat redundant for `numfmt::Part::Copy` to contain a `&[u8]` instead of a `&str`, given that all of its current consumers ultimately expect valid UTF-8. Is the type also intended to work for byte-slice formatting in the future?
Document `Pin` memory layout
The fact that `Pin` is `#[repr(transparent)]` technically isn't documented anywhere currently. I don't see any reason why `Pin`'s layout would ever change, so this PR codifies it.
`@rustbot` label +T-libs-api -T-libs +A-docs +A-layout +A-pin
Don't use inner macro in `marker_impls`
Just recurse instead of having to define an inner macro to avoid the problem with expansion binders being misnumbered between the `$meta` and `$T` variables.
cc `@Veykril` this should fixrust-lang/rust-analyzer#14862 since we've gotten rid of the inner macro.
don't skip inference for type in `offset_of!`
Fixes https://github.com/rust-lang/rust/issues/111678 by no longer skipping inference on the type in `offset_of!`. Simply erasing the regions the during writeback isn't enough and can cause ICEs. A test case for this is included.
This reverts https://github.com/rust-lang/rust/pull/111661, because it becomes redundant, since inference already erases the regions.
Use code with reliable branchless code-gen for slice::sort merge
The recent LLVM 16 update changes code-gen to be not branchless anymore, in the slice::sort implementation merge function. This improves performance by 30% for random patterns, restoring the performance to the state with LLVM 15.
Fixes#111559
Rollup of 10 pull requests
Successful merges:
- #111491 (Dont check `must_use` on nested `impl Future` from fn)
- #111606 (very minor cleanups)
- #111619 (Add timings for MIR passes to profiling report)
- #111652 (Better diagnostic for `use Self::..`)
- #111665 (Add more tests for the offset_of macro)
- #111708 (Give a more useful location for where a span_bug was delayed)
- #111715 (Fix doc comment for `ConstParamTy` derive)
- #111723 (style: do not overwrite obligations)
- #111743 (Improve cgu merging debug output)
- #111762 (fix: emit error when fragment is `MethodReceiverExpr` and items is empty)
r? `@ghost`
`@rustbot` modify labels: rollup
Add more tests for the offset_of macro
Implements what I [suggested in the tracking issue](https://github.com/rust-lang/rust/issues/106655#issuecomment-1535007205), plus some further improvements:
* ensuring that offset_of!(Self, ...) works iff inside an impl block
* ensuring that the output type is usize and doesn't coerce. this can be changed in the future, but if it is done, it should be a conscious decision
* improving the privacy checking test
* ensuring that generics don't let you escape the unsized check
r? `````@WaffleLapkin`````
`ascii::Char`-ify the escaping code in `core`
This means that `EscapeIterInner::as_str` no longer needs unsafe code, because the type system ensures the internal buffer is only ASCII, and thus valid UTF-8.
Come to think of it, this also gives it a (non-guaranteed) niche.
cc `@BurntSushi` as potentially interested
`ascii::Char` tracking issue: #110998
Shorten even more panic temporary lifetimes
Followup to #104134. As pointed out by `@bjorn3` in https://github.com/rust-lang/rust/pull/104134#pullrequestreview-1425585948, there are other cases in the panic macros which would also benefit from dropping their non-Send temporaries as soon as possible, avoiding pointlessly holding them across an await point.
For the tests added in this PR, here are the failures you get today on master without the macro changes in this PR:
<details>
<summary>tests/ui/macros/panic-temporaries-2018.rs</summary>
```console
error: future cannot be sent between threads safely
--> tests/ui/macros/panic-temporaries-2018.rs:52:18
|
LL | require_send(panic_display());
| ^^^^^^^^^^^^^^^ future returned by `panic_display` is not `Send`
|
= help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `*const u8`
note: future is not `Send` as this value is used across an await
--> tests/ui/macros/panic-temporaries-2018.rs:35:31
|
LL | f(panic!("{}", NOT_SEND)).await;
| -------- ^^^^^- `NOT_SEND` is later dropped here
| | |
| | await occurs here, with `NOT_SEND` maybe used later
| has type `NotSend` which is not `Send`
note: required by a bound in `require_send`
--> tests/ui/macros/panic-temporaries-2018.rs:48:25
|
LL | fn require_send(_: impl Send) {}
| ^^^^ required by this bound in `require_send`
error: future cannot be sent between threads safely
--> tests/ui/macros/panic-temporaries-2018.rs:52:18
|
LL | require_send(panic_display());
| ^^^^^^^^^^^^^^^ future returned by `panic_display` is not `Send`
|
= help: within `NotSend`, the trait `Sync` is not implemented for `*const u8`
note: future is not `Send` as this value is used across an await
--> tests/ui/macros/panic-temporaries-2018.rs:35:31
|
LL | f(panic!("{}", NOT_SEND)).await;
| ---------------------- ^^^^^- the value is later dropped here
| | |
| | await occurs here, with the value maybe used later
| has type `&NotSend` which is not `Send`
note: required by a bound in `require_send`
--> tests/ui/macros/panic-temporaries-2018.rs:48:25
|
LL | fn require_send(_: impl Send) {}
| ^^^^ required by this bound in `require_send`
error: future cannot be sent between threads safely
--> tests/ui/macros/panic-temporaries-2018.rs:53:18
|
LL | require_send(panic_str());
| ^^^^^^^^^^^ future returned by `panic_str` is not `Send`
|
= help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `*const u8`
note: future is not `Send` as this value is used across an await
--> tests/ui/macros/panic-temporaries-2018.rs:40:36
|
LL | f(panic!((NOT_SEND, "...").1)).await;
| -------- ^^^^^- `NOT_SEND` is later dropped here
| | |
| | await occurs here, with `NOT_SEND` maybe used later
| has type `NotSend` which is not `Send`
note: required by a bound in `require_send`
--> tests/ui/macros/panic-temporaries-2018.rs:48:25
|
LL | fn require_send(_: impl Send) {}
| ^^^^ required by this bound in `require_send`
error: future cannot be sent between threads safely
--> tests/ui/macros/panic-temporaries-2018.rs:54:18
|
LL | require_send(unreachable_display());
| ^^^^^^^^^^^^^^^^^^^^^ future returned by `unreachable_display` is not `Send`
|
= help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `*const u8`
note: future is not `Send` as this value is used across an await
--> tests/ui/macros/panic-temporaries-2018.rs:45:31
|
LL | f(unreachable!(NOT_SEND)).await;
| -------- ^^^^^- `NOT_SEND` is later dropped here
| | |
| | await occurs here, with `NOT_SEND` maybe used later
| has type `NotSend` which is not `Send`
note: required by a bound in `require_send`
--> tests/ui/macros/panic-temporaries-2018.rs:48:25
|
LL | fn require_send(_: impl Send) {}
| ^^^^ required by this bound in `require_send`
error: future cannot be sent between threads safely
--> tests/ui/macros/panic-temporaries-2018.rs:54:18
|
LL | require_send(unreachable_display());
| ^^^^^^^^^^^^^^^^^^^^^ future returned by `unreachable_display` is not `Send`
|
= help: within `NotSend`, the trait `Sync` is not implemented for `*const u8`
note: future is not `Send` as this value is used across an await
--> tests/ui/macros/panic-temporaries-2018.rs:45:31
|
LL | f(unreachable!(NOT_SEND)).await;
| ---------------------- ^^^^^- the value is later dropped here
| | |
| | await occurs here, with the value maybe used later
| has type `&NotSend` which is not `Send`
note: required by a bound in `require_send`
--> tests/ui/macros/panic-temporaries-2018.rs:48:25
|
LL | fn require_send(_: impl Send) {}
| ^^^^ required by this bound in `require_send`
error: aborting due to 5 previous errors
```
</details>
<details>
<summary>tests/ui/macros/panic-temporaries.rs</summary>
```console
error: future cannot be sent between threads safely
--> tests/ui/macros/panic-temporaries.rs:42:18
|
LL | require_send(panic_display());
| ^^^^^^^^^^^^^^^ future returned by `panic_display` is not `Send`
|
= help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `*const u8`
note: future is not `Send` as this value is used across an await
--> tests/ui/macros/panic-temporaries.rs:35:31
|
LL | f(panic!("{}", NOT_SEND)).await;
| -------- ^^^^^- `NOT_SEND` is later dropped here
| | |
| | await occurs here, with `NOT_SEND` maybe used later
| has type `NotSend` which is not `Send`
note: required by a bound in `require_send`
--> tests/ui/macros/panic-temporaries.rs:38:25
|
LL | fn require_send(_: impl Send) {}
| ^^^^ required by this bound in `require_send`
error: future cannot be sent between threads safely
--> tests/ui/macros/panic-temporaries.rs:42:18
|
LL | require_send(panic_display());
| ^^^^^^^^^^^^^^^ future returned by `panic_display` is not `Send`
|
= help: within `NotSend`, the trait `Sync` is not implemented for `*const u8`
note: future is not `Send` as this value is used across an await
--> tests/ui/macros/panic-temporaries.rs:35:31
|
LL | f(panic!("{}", NOT_SEND)).await;
| ---------------------- ^^^^^- the value is later dropped here
| | |
| | await occurs here, with the value maybe used later
| has type `&NotSend` which is not `Send`
note: required by a bound in `require_send`
--> tests/ui/macros/panic-temporaries.rs:38:25
|
LL | fn require_send(_: impl Send) {}
| ^^^^ required by this bound in `require_send`
error: aborting due to 2 previous errors
```
</details>
r? bjorn3
* ensuring that offset_of!(Self, ...) works iff inside an impl block
* ensuring that the output type is usize and doesn't coerce. this can be
changed in the future, but if it is done, it should be a conscious descision
* improving the privacy checking test
* ensuring that generics don't let you escape the unsized check
Add a conversion from `&mut T` to `&mut UnsafeCell<T>`
Provides a safe way of downgrading an exclusive reference into an alias-able `&UnsafeCell<T>` reference.
ACP: https://github.com/rust-lang/libs-team/issues/198.
The recent LLVM 16 update changes code-gen to be not branchless anymore, in the
slice::sort implementation merge function. This improves performance by 30% for
random patterns, restoring the performance to the state with LLVM 15.
Fix some misleading and copy-pasted `Pattern` examples
These examples were listed twice and also were confusable with doing a substring match instead of a any-of-set match.
Update doc for `PhantomData` to match code example
After https://github.com/rust-lang/rust/pull/106621, there is no longer a `T: 'a` annotation in the doc example, so update the text to match the code.
Stabilize const slice::split_at
This stabilizes the use of the following method in const context:
```rust
impl<T> [T] {
pub const fn split_at(&self, mid: usize) -> (&[T], &[T]);
}
```
cc tracking issue #101158
Add midpoint function for all integers and floating numbers
This pull-request adds the `midpoint` function to `{u,i}{8,16,32,64,128,size}`, `NonZeroU{8,16,32,64,size}` and `f{32,64}`.
This new function is analog to the [C++ midpoint](https://en.cppreference.com/w/cpp/numeric/midpoint) function, and basically compute `(a + b) / 2` with a rounding towards ~~`a`~~ negative infinity in the case of integers. Or simply said: `midpoint(a, b)` is `(a + b) >> 1` as if it were performed in a sufficiently-large signed integral type.
Note that unlike the C++ function this pull-request does not implement this function on pointers (`*const T` or `*mut T`). This could be implemented in a future pull-request if desire.
### Implementation
For `f32` and `f64` the implementation in based on the `libcxx` [one](18ab892ff7/libcxx/include/__numeric/midpoint.h (L65-L77)). I originally tried many different approach but all of them failed or lead me with a poor version of the `libcxx`. Note that `libstdc++` has a very similar one; Microsoft STL implementation is also basically the same as `libcxx`. It unfortunately doesn't seems like a better way exist.
For unsigned integers I created the macro `midpoint_impl!`, this macro has two branches:
- The first one take `$SelfT` and is used when there is no unsigned integer with at least the double of bits. The code simply use this formula `a + (b - a) / 2` with the arguments in the correct order and signs to have the good rounding.
- The second branch is used when a `$WideT` (at least double of bits as `$SelfT`) is provided, using a wider number means that no overflow can occur, this greatly improve the codegen (no branch and less instructions).
For signed integers the code basically forwards the signed numbers to the unsigned version of midpoint by mapping the signed numbers to their unsigned numbers (`ex: i8 [-128; 127] to [0; 255]`) and vice versa.
I originally created a version that worked directly on the signed numbers but the code was "ugly" and not understandable. Despite this mapping "overhead" the codegen is better than my most optimized version on signed integers.
~~Note that in the case of unsigned numbers I tried to be smart and used `#[cfg(target_pointer_width = "64")]` to determine if using the wide version was better or not by looking at the assembly on godbolt. This was applied to `u32`, `u64` and `usize` and doesn't change the behavior only the assembly code generated.~~
This means that `EscapeIterInner::as_str` no longer needs unsafe code, because the type system ensures the internal buffer is only ASCII, and thus valid UTF-8.
PhantomData: fix documentation wrt interaction with dropck
As far as I could find out, the `PhantomData`-dropck interaction *only* affects code using `may_dangle`. The documentation in the standard library has not been updated for 8 years and thus stems from a time when Rust still used "parametric dropck", before [RFC 1238](https://rust-lang.github.io/rfcs/1238-nonparametric-dropck.html). Back then what the docs said was correct, but with `may_dangle` dropck it stopped being entirely accurate and these days, with NLL, it is actively misleading.
Fixes https://github.com/rust-lang/rust/issues/102810
Fixes https://github.com/rust-lang/rust/issues/70841
Cc `@nikomatsakis` I hope what I am saying here is right.^^
Uplift `clippy::{drop,forget}_{ref,copy}` lints
This PR aims at uplifting the `clippy::drop_ref`, `clippy::drop_copy`, `clippy::forget_ref` and `clippy::forget_copy` lints.
Those lints are/were declared in the correctness category of clippy because they lint on useless and most probably is not what the developer wanted.
## `drop_ref` and `forget_ref`
The `drop_ref` and `forget_ref` lint checks for calls to `std::mem::drop` or `std::mem::forget` with a reference instead of an owned value.
### Example
```rust
let mut lock_guard = mutex.lock();
std::mem::drop(&lock_guard) // Should have been drop(lock_guard), mutex
// still locked
operation_that_requires_mutex_to_be_unlocked();
```
### Explanation
Calling `drop` or `forget` on a reference will only drop the reference itself, which is a no-op. It will not call the `drop` or `forget` method on the underlying referenced value, which is likely what was intended.
## `drop_copy` and `forget_copy`
The `drop_copy` and `forget_copy` lint checks for calls to `std::mem::forget` or `std::mem::drop` with a value that derives the Copy trait.
### Example
```rust
let x: i32 = 42; // i32 implements Copy
std::mem::forget(x) // A copy of x is passed to the function, leaving the
// original unaffected
```
### Explanation
Calling `std::mem::forget` [does nothing for types that implement Copy](https://doc.rust-lang.org/std/mem/fn.drop.html) since the value will be copied and moved into the function on invocation.
-----
Followed the instructions for uplift a clippy describe here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
cc `@m-ou-se` (as T-libs-api leader because the uplifting was discussed in a recent meeting)
Simplify the implementation of iterators over slices of ZSTs
Currently, slice iterators over ZSTs store `end = start.wrapping_byte_add(len)`.
That's slightly convenient for `is_empty`, but kinda annoying for pretty much everything else -- see bugs like #42789, for example.
This PR instead changes it to just `end = ptr::invalid(len)` instead.
That's easier to think about (IMHO, at least) as well as easier to represent.
`next` is still to big to get inlined into the mir-opt/pre-codegen/ tests, but if I bump the inline threshold to force it to show the whole thing, this implementation is also less MIR:
```
> git diff --numstat
241 370 tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.mir
255 329 tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.mir
184 216 tests/mir-opt/pre-codegen/slice_iter.slice_iter_mut_next_back.PreCodegen.after.mir
182 254 tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.mir
```
(That's ≈70 lines less for `Iter::next`, for example.)
r? `@ghost`
~~Built atop #111282, so draft until that lands.~~
Currently, slice iterators over ZSTs store `end = start.wrapping_byte_add(len)`.
That's slightly convenient for `is_empty`, but kinda annoying for pretty much everything else -- see bugs like 42789, for example.
This PR instead changes it to just `end = ptr::invalid(len)` instead.
That's easier to think about (IMHO, at least) as well as easier to represent.
Fix incorrect implication of transmuting slices
transmute<&[u8]> would be useful and as a beginner it is confusing to see documents casually confuse the types of &[u8] and [u8; SZ]
Remove some `assume`s from slice iterators that don't do anything
Because the start pointer is iterators is already a `NonNull`, we emit the appropriate `!nonnull` metadata when loading the pointer to tell LLVM that it's non-null.
Probably the best way to see that it's the metadata that's important (and not the `assume`) is to observe that LLVM actually *removes* the `assume` from the optimized IR: <https://rust.godbolt.org/z/KhE6G963n>.
(I also checked that, yes, the if-not-ZST `assume` on `end` is still doing something: it's how there's a `!nonnull` metadata on its load, even though it's an ordinary raw pointer. The codegen test added in this PR fails if the other `assume` is removed.)
Revert "Populate effective visibilities in `rustc_privacy`"
This reverts commit cff85f22f5, cc #110907. It needs to be fixed, but there are too many issues being reported that I wanted to put up a revert until a proper fix can be committed.
Fixes a ton of issues where private but still reachable impls were missing during codegen:
Fixes#111320Fixes#111321Fixes#111334Fixes#111357Fixes#111368Fixes#111373Fixes#111377Fixes#111386Fixes#111387
`@bors` p=1
r? `@petrochenkov`
Implement builtin # syntax and use it for offset_of!(...)
Add `builtin #` syntax to the parser, as well as a generic infrastructure to support both item and expression position builtin syntaxes. The PR also uses this infrastructure for the implementation of the `offset_of!` macro, added by #106934.
cc `@petrochenkov` `@DrMeepster`
cc #110680 `builtin #` tracking issue
cc #106655 `offset_of!` tracking issue
Add `#[inline]` to functions that are never called
This makes libcore binary size reduce by ~300 bytes. Not much, but these functions are never called so it doesn't make sense for them to get into the binary anyway.
Always const-evaluate the GCD in `slice::align_to_offsets`
Use an inline `const`-block to force the compiler to calculate the GCD at compile time, even in debug mode. This shouldn't affect the behavior of the program at all, but it drastically cuts down on the number of instructions emitted with optimizations disabled.
With the current implementation, a single `slice::align_to` instantiation (specifically `<[u8]>::align_to::<u128>()`) generates 676 instructions (on x86-64). Forcing the GCD computation to be const cuts it down to 327 instructions, so just over 50% less. This is obviously not representative of actual runtime gains, but I still see it as a significant win as long as it doesn't degrade compile times.
Not having to worry about LLVM const-evaluating the GCD function also allows it to use the textbook recursive euclidean algorithm instead of a much more complicated iterative implementation with multiple `unsafe`-blocks.
Remove `identity_future` from stdlib
This function/lang_item was introduced in #104321 as a temporary workaround of future lowering. The usage and need for it went away in #104833.
After a bootstrap update, the function itself can be removed from `std`.
enable `rust_2018_idioms` lint group for doctests
With this change, `rust_2018_idioms` lint group will be enabled for compiler/libstd doctests.
Resolves#106086Resolves#99144
Signed-off-by: ozkanonur <work@onurozkan.dev>
Constify `[u8]::is_ascii` (unstably)
UTF-8 checking in `const fn`-stabilized back in 1.63 (#97367), but apparently somehow ASCII checking was never const-ified, despite being simpler.
New constness-tracking issue for `is_ascii`: #111090
I noticed this working on `ascii::Char`: #110998
This function/lang_item was introduced in #104321 as a temporary workaround of future lowering.
The usage and need for it went away in #104833.
After a bootstrap update, the function itself can be removed from `std`.
Remove calls to `mem::forget` and `mem::replace` in `Option::get_or_insert_with`.
This removes the unneeded calls to `mem::forget` and `mem::replace` in `Option::get_or_insert_with`.
clean up `transmute`s in `core`
* Use `transmute_unchecked` instead of `transmute_copy` for `MaybeUninit::transpose`.
* Use manual transmute for `Option<Ordering>` → `i8`.
Add cross-language LLVM CFI support to the Rust compiler
This PR adds cross-language LLVM Control Flow Integrity (CFI) support to the Rust compiler by adding the `-Zsanitizer-cfi-normalize-integers` option to be used with Clang `-fsanitize-cfi-icall-normalize-integers` for normalizing integer types (see https://reviews.llvm.org/D139395).
It provides forward-edge control flow protection for C or C++ and Rust -compiled code "mixed binaries" (i.e., for when C or C++ and Rust -compiled code share the same virtual address space). For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler, see design document in the tracking issue #89653.
Cross-language LLVM CFI can be enabled with -Zsanitizer=cfi and -Zsanitizer-cfi-normalize-integers, and requires proper (i.e., non-rustc) LTO (i.e., -Clinker-plugin-lto).
Thank you again, ``@bjorn3,`` ``@nikic,`` ``@samitolvanen,`` and the Rust community for all the help!
Implement tuple<->array convertions via `From`
This PR adds the following impls that convert between homogeneous tuples and arrays of the corresponding lengths:
```rust
impl<T> From<[T; 1]> for (T,) { ... }
impl<T> From<[T; 2]> for (T, T) { ... }
/* ... */
impl<T> From<[T; 12]> for (T, T, T, T, T, T, T, T, T, T, T, T) { ... }
impl<T> From<(T,)> for [T; 1] { ... }
impl<T> From<(T, T)> for [T; 2] { ... }
/* ... */
impl<T> From<(T, T, T, T, T, T, T, T, T, T, T, T)> for [T; 12] { ... }
```
IMO these are quite uncontroversial but note that they are, just like any other trait impls, insta-stable.
This commit adds cross-language LLVM Control Flow Integrity (CFI)
support to the Rust compiler by adding the
`-Zsanitizer-cfi-normalize-integers` option to be used with Clang
`-fsanitize-cfi-icall-normalize-integers` for normalizing integer types
(see https://reviews.llvm.org/D139395).
It provides forward-edge control flow protection for C or C++ and Rust
-compiled code "mixed binaries" (i.e., for when C or C++ and Rust
-compiled code share the same virtual address space). For more
information about LLVM CFI and cross-language LLVM CFI support for the
Rust compiler, see design document in the tracking issue #89653.
Cross-language LLVM CFI can be enabled with -Zsanitizer=cfi and
-Zsanitizer-cfi-normalize-integers, and requires proper (i.e.,
non-rustc) LTO (i.e., -Clinker-plugin-lto).
Add `ConstParamTy` trait
This is a bit sketch, but idk.
r? `@BoxyUwU`
Yet to be done:
- [x] ~~Figure out if it's okay to implement `StructuralEq` for primitives / possibly remove their special casing~~ (it should be okay, but maybe not in this PR...)
- [ ] Maybe refactor the code a little bit
- [x] Use a macro to make impls a bit nicer
Future work:
- [ ] Actually™ use the trait when checking if a `const` generic type is allowed
- [ ] _Really_ refactor the surrounding code
- [ ] Refactor `marker.rs` into multiple modules for each "theme" of markers
Refactor core::char::EscapeDefault and co. structures
Change core::char::{EscapeUnicode, EscapeDefault and EscapeDebug}
structures from using a state machine to computing escaped sequence
upfront and during iteration just going through the characters.
This is arguably simpler since it’s easier to think about having
a buffer and start..end range to iterate over rather than thinking
about a state machine.
This also harmonises implementation of aforementioned iterators and
core::ascii::EscapeDefault struct. This is done by introducing a new
helper EscapeIterInner struct which holds the buffer and offers simple
methods for iterating over range.
As a side effect, this probably optimises Display implementation for
those types since rather than calling write_char repeatedly, write_str
is invoked once. On 64-bit platforms, it also reduces size of some of
the structs:
| Struct | Before | After |
|----------------------------+--------+-------+
| core::char::EscapeUnicode | 16 | 12 |
| core::char::EscapeDefault | 16 | 12 |
| core::char::EscapeDebug | 16 | 16 |
My ulterior motive and reason why I started looking into this is
addition of as_str method to the iterators. With this change this
will became trivial. It’s also going to be trivial to implement
DoubleEndedIterator if that’s ever desired.
Some of these relations were already mentioned in the text, but that
Send is implemented for &mut impl Send was not mentioned,
neither did the docs list when &T is Sync.
Make `mem::replace` simpler in codegen
Since they'd mentioned more intrinsics for simplifying stuff recently,
r? `@WaffleLapkin`
This is a continuation of me looking at foundational stuff that ends up with more instructions than it really needs. Specifically I noticed this one because `Range::next` isn't MIR-inlining, and one of the largest parts of it is a `replace::<usize>` that's a good dozen instructions instead of the two it could be.
So this means that `ptr::write` with a `Copy` type no longer generates worse IR than manually dereferencing (well, at least in LLVM -- MIR still has bonus pointer casts), and in doing so means that we're finally down to just the two essential `memcpy`s when emitting `mem::replace` for a large type, rather than the bonus-`alloca` and three `memcpy`s we emitted before this ([or the 6 we currently emit in 1.69 stable](https://rust.godbolt.org/z/67W8on6nP)). That said, LLVM does _usually_ manage to optimize the extra code away. But it's still nice for it not to have to do as much, thanks to (for example) not going through an `alloca` when `replace`ing a primitive like a `usize`.
(This is a new intrinsic, but one that's immediately lowered to existing MIR constructs, so not anything that MIRI or the codegen backends or MIR semantics needs to do work to handle.)
Tweak await span to not contain dot
Fixes a discrepancy between method calls and await expressions where the latter are desugared to have a span that *contains* the dot (i.e. `.await`) but method call identifiers don't contain the dot. This leads to weird suggestions suggestions in borrowck -- see linked issue.
Fixes#110761
This mostly touches a bunch of tests to tighten their `await` span.
`inline(always)` for `lt`/`le`/`ge`/`gt` on integers and floats
I happened to notice one of these not getting inlined as part of `Range::next` in <https://rust.godbolt.org/z/4WKWWxj1G>
```rust
bb1: {
StorageLive(_5);
_6 = &mut _4;
StorageLive(_21);
StorageLive(_14);
StorageLive(_15);
_15 = &((*_6).0: usize);
StorageLive(_16);
_16 = &((*_6).1: usize);
_14 = <usize as PartialOrd>::lt(move _15, move _16) -> bb7;
}
```
So since a call for something that's just one instruction is never the right choice, `#[inline(always)]` seems appropriate, like we have it on things like the rotate methods on integers.
Improve internal field comments on `slice::Iter(Mut)`
I wrote these in a previous PR that I ended up withdrawing, so might as well submit them separately.
`@bors` rollup=always
Make sure that some stdlib method signatures aren't accidental refinements
In the process of implementing https://rust-lang.github.io/rfcs/3245-refined-impls.html, I found a bunch of stdlib implementations that accidentally "refined" their method signatures by dropping (unnecessary) bounds.
This isn't currently a problem, but may become one if/when method signature refining is stabilized in the future. Shouldn't hurt to make these signatures a bit more accurate anyways.
NOTE (just to be clear lol): This does not affect behavior at all, since we don't actually take advantage of refined implementations yet!
Use MIR's `Offset` for pointer `add` too
~~Status: draft while waiting for #110822 to land, since this is built atop that.~~
~~r? `@ghost~~`
Canonical Rust code has mostly moved to `add`/`sub` on pointers, which take `usize`, instead of `offset` which takes `isize`. (And, relatedly, when `sub_ptr` was added it turned out it replaced every single in-tree use of `offset_from`, because `usize` is just so much more useful than `isize` in Rust.)
Unfortunately, `intrinsics::offset` could only accept `*const` and `isize`, so there's a *huge* amount of type conversions back and forth being done. They're identity conversions in the backend, but still end up producing quite a lot of unhelpful MIR.
This PR changes `intrinsics::offset` to accept `*const` *and* `*mut` along with `isize` *and* `usize`. Conveniently, the backends and CTFE already handle this, since MIR's `BinOp::Offset` [already supports all four combinations](adaac6b166/compiler/rustc_const_eval/src/transform/validate.rs (L523-L528)).
To demonstrate the difference, I added some `mir-opt/pre-codegen/` tests around slice indexing. Here's the difference to `[T]::get_mut`, since it uses `<*mut _>::add` internally:
```diff
`@@` -79,30 +70,21 `@@` fn slice_get_mut_usize(_1: &mut [u32], _2: usize) -> Option<&mut u32> {
StorageLive(_12); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageLive(_9); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
_9 = _8 as *mut u32 (PtrToPtr); // scope 11 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageLive(_13); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- _13 = _2 as isize (IntToInt); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageLive(_14); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageLive(_15); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- _15 = _9 as *const u32 (Pointer(MutToConstPointer)); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- _14 = Offset(move _15, _13); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageDead(_15); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- _7 = move _14 as *mut u32 (PtrToPtr); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageDead(_14); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageDead(_13); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
+ _7 = Offset(_9, _2); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_9); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_12); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_11); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
```
1c1c8e442a (diff-a841b6a4538657add3f39bc895744331453d0625e7aace128b1f604f0b63c8fdR80)
I happened to notice one of these not getting inlined as part of `Range::next` in <https://rust.godbolt.org/z/4WKWWxj1G>
```rust
bb1: {
StorageLive(_5);
_6 = &mut _4;
StorageLive(_21);
StorageLive(_14);
StorageLive(_15);
_15 = &((*_6).0: usize);
StorageLive(_16);
_16 = &((*_6).1: usize);
_14 = <usize as PartialOrd>::lt(move _15, move _16) -> bb7;
}
```
So since a call for something this trivial is never the right choice, `#[inline(always)]` seems appropriate.
More core::fmt::rt cleanup.
- Removes the `V1` suffix from the `Argument` and `Flag` types.
- Moves more of the format_args lang items into the `core::fmt::rt` module. (The only remaining lang item in `core::fmt` is `Arguments` itself, which is a public type.)
Part of https://github.com/rust-lang/rust/issues/99012
Follow-up to https://github.com/rust-lang/rust/pull/110616
Spelling library
Split per https://github.com/rust-lang/rust/pull/110392
I can squash once people are happy w/ the changes. It's really uncommon for large sets of changes to be perfectly acceptable w/o at least some changes.
I probably won't have time to respond until tomorrow or the next day
black_box doc corrections for clarification - Issue #107957
Made a complete pass through the docs to help resolve https://github.com/rust-lang/rust/issues/107957
No code changes, just documentation
`@rustbot` label +T-libs-api -T-libs
Fix no_global_oom_handling build
`provide_sorted_batch` in core is incorrectly marked with `#[cfg(not(no_global_oom_handling))]` which prevents core from building with the cfg enabled.
Nothing in `core` allocates memory (including this function). The `cfg` gate is incorrect.
cc ``@dpaoliello``
r? ``@wesleywiser``
The cfg was added by #107191
Add shortcut for Grisu3 algorithm.
While Grisu3 is way more faster for most numbers compare to Dragon4, the fall back to Dragon4 procedure for certain numbers could cause some performance regressions compare to use Dragon4 directly. Mitigating the regression caused by falling back is important for a largely used core library.
In Grisu3 algorithm implementation, there's a shortcut to jump out earlier when the fractional or integrals cannot meet the requirement of requested digits. This could significantly improve the performance of converting floating number to string as it falls back even without starting trying the algorithm.
The original idea is from the [.NET implementation](https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.CoreLib/src/System/Number.Grisu3.cs#L602-L615) and the code was originally added in [this PR](https://github.com/dotnet/coreclr/pull/14646#issuecomment-350942050). This shortcut has been shipped long time ago and has been proved working.
Fix#110129
Check requested digit length and the fractional or integral parts of the number. Falls back earlier without trying the Grisu algorithm if the specific condition meets.
Fix#110129
Add `intrinsics::transmute_unchecked`
This takes a whole 3 lines in `compiler/` since it lowers to `CastKind::Transmute` in MIR *exactly* the same as the existing `intrinsics::transmute` does, it just doesn't have the fancy checking in `hir_typeck`.
Added to enable experimenting with the request in <https://github.com/rust-lang/rust/pull/106281#issuecomment-1496648190> and because the portable-simd folks might be interested for dependently-sized array-vector conversions.
It also simplifies a couple places in `core`.
See also https://github.com/rust-lang/rust/pull/108442#issuecomment-1474777273, where `CastKind::Transmute` was added having exactly these semantics before the lang meeting (which I wasn't in) independently expressed interest.
This takes a whole 3 lines in `compiler/` since it lowers to `CastKind::Transmute` in MIR *exactly* the same as the existing `intrinsics::transmute` does, it just doesn't have the fancy checking in `hir_typeck`.
Added to enable experimenting with the request in <https://github.com/rust-lang/rust/pull/106281#issuecomment-1496648190> and because the portable-simd folks might be interested for dependently-sized array-vector conversions.
It also simplifies a couple places in `core`.
Report allocation errors as panics
OOM is now reported as a panic but with a custom payload type (`AllocErrorPanicPayload`) which holds the layout that was passed to `handle_alloc_error`.
This should be review one commit at a time:
- The first commit adds `AllocErrorPanicPayload` and changes allocation errors to always be reported as panics.
- The second commit removes `#[alloc_error_handler]` and the `alloc_error_hook` API.
ACP: https://github.com/rust-lang/libs-team/issues/192Closes#51540Closes#51245
More `IS_ZST` in `library`
I noticed that `post_inc_start` and `pre_dec_end` were doing this check in different ways
d19b64fb54/library/core/src/slice/iter/macros.rs (L76-L93)
so started making this PR, then added a few more I found since I was already making changes anyway.
Add offset_of! macro (RFC 3308)
Implements https://github.com/rust-lang/rfcs/pull/3308 (tracking issue #106655) by adding the built in macro `core::mem::offset_of`. Two of the future possibilities are also implemented:
* Nested field accesses (without array indexing)
* DST support (for `Sized` fields)
I wrote this a few months ago, before the RFC merged. Now that it's merged, I decided to rebase and finish it.
cc `@thomcc` (RFC author)
I noticed that `post_inc_start` and `pre_dec_end` were doing this check in different ways
d19b64fb54/library/core/src/slice/iter/macros.rs (L76-L93)
so started making this PR, then added a few more I found since I was already making changes anyway.
`provide_sorted_batch` in core is incorrectly marked with
`#[cfg(not(no_global_oom_handling))]` which prevents core
from building with the cfg enabled.
Nothing in core allocates memory including this function, so
the `cfg` gate is incorrect.
Negating a non-zero integer currently requires unpacking to a
primitive and re-wrapping. Since negation of non-zero signed
integers always produces a non-zero result, it is safe to
implement `Neg` for `NonZeroI{N}`.
The new `impl` is marked as stable because trait implementations
for two stable types can't be marked unstable.
`Mutex` prints `<locked>` as a field value when its inner value cannot be accessed, but the lazy types print a fixed string like "`OnceCell(Uninit)`". This could cause confusion if the inner type is a unit type named `Uninit` and does not respect the pretty-printing flag. With this change, the format message is now "`OnceCell(<uninit>)`", consistent with `Mutex`.
Use `Display` in top-level example for `PanicInfo`
Addresses https://github.com/rust-lang/rust/issues/110098.
This confused me as well, when I was writing a `no_std` panic handler for the first time, so here's a better top-level example.
`Display` is stable, prints the `.message()` if available, and falls back to `.payload().downcast_ref<&str>()` if the message is not available. So this example should provide strictly more information and also work for formatted panics.
The old example still exists on the `payload` method.
Add links from `core::cmp` derives to their traits
Fixes#109946
Adds intra-doc links from the `core::cmp` derives to their respective traits, and a link to their derive behaviour
`@rustbot` label +A-docs
Add `tidy-alphabetical` to features in `core`
So that people have to keep them sorted in future, rather than just sticking them on the end where they conflict more often.
Remove obsolete test case
This test case was supposed to cover issue #31109 at some point.
It never did anything, as the issue was still open at the time of its creation.
When the issue was resolved, the `issue31109` test case was created,
making the existence of this test pointless.
Improve safe transmute error reporting
This patch updates the error reporting when Safe Transmute is not possible between 2 types by including the reason.
Also, fix some small bugs that occur when computing the `Answer` for transmutability.
This patch updates the error reporting when Safe Transmute is not
possible between 2 types by including the reason.
Also, fix some small bugs that occur when computing the `Answer` for
transmutability.
Added diagnostic for pin! macro in addition to Box::pin if Unpin isn't implemented
I made a PR earlier, but accidentally renamed a branch and that deleted the PR... sorry for the duplicate
Currently, if an operation on `Pin<T>` is performed that requires `T` to implement `Unpin`, the diagnostic suggestion is to use `Box::pin` ("note: consider using `Box::pin`").
This PR suggests pin! as well, as that's another valid way of pinning a value, and avoids a heap allocation. Appropriate diagnostic suggestions were included to highlight the difference in semantics (local pinning for pin! vs non-local for Box::pin).
Fixes#109964
Custom MIR: Support `BinOp::Offset`
Since offset doesn't have an infix operator, a new function `Offset` is added which is lowered to `Rvalue::BinaryOp(BinOp::Offset, ..)`
r? ```@oli-obk``` or ```@tmiasko``` or ```@JakobDegen```
