Optimizing the rest of bool's Ord implementation
After coming across issue #66780, I realized that the other functions provided by Ord (`min`, `max`, and `clamp`) were similarly inefficient for bool. This change provides implementations for them in terms of boolean operators, resulting in much simpler assembly and faster code.
Fixes issue #114653
[Comparison on Godbolt](https://rust.godbolt.org/z/5nb5P8e8j)
`max` assembly before:
```assembly
example::max:
mov eax, edi
mov ecx, eax
neg cl
mov edx, esi
not dl
cmp dl, cl
cmove eax, esi
ret
```
`max` assembly after:
```assembly
example::max:
mov eax, edi
or eax, esi
ret
```
`clamp` assembly before:
```assembly
example:🗜️
mov eax, esi
sub al, dl
inc al
cmp al, 2
jae .LBB1_1
mov eax, edi
sub al, sil
movzx ecx, dil
sub dil, dl
cmp dil, 1
movzx edx, dl
cmovne edx, ecx
cmp al, -1
movzx eax, sil
cmovne eax, edx
ret
.LBB1_1:
; identical assert! code
```
`clamp` assembly after:
```assembly
example:🗜️
test edx, edx
jne .LBB1_2
test sil, sil
jne .LBB1_3
.LBB1_2:
or dil, sil
and dil, dl
mov eax, edi
ret
.LBB1_3:
; identical assert! code
```
Cleaner assert_eq! & assert_ne! panic messages
This PR finishes refactoring of the assert messages per #94005. The panic message format change #112849 used to be part of this PR, but has been factored out and just merged. It might be better to keep both changes in the same release once FCP vote completes.
Modify panic message for `assert_eq!`, `assert_ne!`, the currently unstable `assert_matches!`, as well as the corresponding `debug_assert_*` macros.
```rust
assert_eq!(1 + 1, 3);
assert_eq!(1 + 1, 3, "my custom message value={}!", 42);
```
#### Old messages
```plain
thread 'main' panicked at $DIR/main.rs:6:5:
assertion failed: `(left == right)`
left: `2`,
right: `3`
```
```plain
thread 'main' panicked at $DIR/main.rs:6:5:
assertion failed: `(left == right)`
left: `2`,
right: `3`: my custom message value=42!
```
#### New messages
```plain
thread 'main' panicked at $DIR/main.rs:6:5:
assertion `left == right` failed
left: 2
right: 3
```
```plain
thread 'main' panicked at $DIR/main.rs:6:5:
assertion `left == right` failed: my custom message value=42!
left: 2
right: 3
```
History of fixing #94005
* #94016 was a lengthy PR that was abandoned
* #111030 was similar, but it stringified left and right arguments, and thus caused compile time performance issues, thus closed
* #112849 factored out the two-line formatting of all panic messages
Fixes#94005
r? `@m-ou-se`
Modify panic message for `assert_eq!`, `assert_ne!`, the currently unstable `assert_matches!`, as well as the corresponding `debug_assert_*` macros.
```rust
assert_eq!(1 + 1, 3);
assert_eq!(1 + 1, 3, "my custom message value={}!", 42);
```
```plain
thread 'main' panicked at $DIR/main.rs:6:5:
assertion failed: `(left == right)`
left: `2`,
right: `3`
```
```plain
thread 'main' panicked at $DIR/main.rs:6:5:
assertion failed: `(left == right)`
left: `2`,
right: `3`: my custom message value=42!
```
```plain
thread 'main' panicked at $DIR/main.rs:6:5:
assertion `left == right` failed
left: 2
right: 3
```
```plain
thread 'main' panicked at $DIR/main.rs:6:5:
assertion `left == right` failed: my custom message value=42!
left: 2
right: 3
```
This PR is a simpler subset of the #111030, but it does NOT stringify the original left and right source code assert expressions, thus should be faster to compile.
Rollup of 10 pull requests
Successful merges:
- #114711 (Infer `Lld::No` linker hint when the linker stem is a generic compiler driver)
- #114772 (Add `{Local}ModDefId` to more strongly type DefIds`)
- #114800 (std: add some missing repr(transparent))
- #114820 (Add test for unknown_lints from another file.)
- #114825 (Upgrade std to gimli 0.28.0)
- #114827 (Only consider object candidates for object-safe dyn types in new solver)
- #114828 (Probe when assembling upcast candidates so they don't step on eachother's toes in new solver)
- #114829 (Separate `consider_unsize_to_dyn_candidate` from other unsize candidates)
- #114830 (Clean up some bad UI testing annotations)
- #114831 (Check projection args before substitution in new solver)
r? `@ghost`
`@rustbot` modify labels: rollup
Don't panic in ceil_char_boundary
Implementing the alternative mentioned in this comment: https://github.com/rust-lang/rust/issues/93743#issuecomment-1579935853
Since `floor_char_boundary` will always work (rounding down to the length of the string is possible), it feels best for `ceil_char_boundary` to not panic either. However, the semantics of "rounding up" past the length of the string aren't very great, which is why the method originally panicked in these cases.
Taking into account how people are using this method, it feels best to simply return the end of the string in these cases, so that the result is still a valid char boundary.
std: add some missing repr(transparent)
For some types we don't want to stably guarantee this, so hide the `repr` from rustdoc. This nice approach was suggested by `@thomcc.`
add a csky-unknown-linux-gnuabiv2 target
This is the rustc side changes to support csky based Linux target(`csky-unknown-linux-gnuabiv2`).
Tier 3 policy:
> A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)
I pledge to do my best maintaining it.
> Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.
This `csky` section is the arch name and the `unknown-linux` section is the same as other linux target, and `gnuabiv2` is from the cross-compile toolchain of `gcc`
> Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.
I think the explanation in platform support doc is enough to make this aspect clear.
> Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.
It's using open source tools only.
> The target must not introduce license incompatibilities.
No new license
> Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0).
Understood.
> The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.
There are no new dependencies/features required.
> Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.
As previously said it's using open source tools only.
> "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.
There are no such terms present/
> Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.
I'm not the reviewer here.
> This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements.
I'm not the reviewer here.
> Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.
It supports for std
> The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary.
I have added the documentation, and I think it's clear.
> Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.
Understood.
> Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.
Understood.
> Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.
I believe I didn't break any other target.
> In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.
I think there are no such problems in this PR.
core/any: remove Provider trait, rename Demand to Request
This touches on two WIP features:
* `error_generic_member_access`
* tracking issue: https://github.com/rust-lang/rust/issues/99301
* RFC (WIP): https://github.com/rust-lang/rfcs/pull/2895
* `provide_any`
* tracking issue: https://github.com/rust-lang/rust/issues/96024
* RFC: https://github.com/rust-lang/rfcs/pull/3192
The changes in this PR are intended to address libs meeting feedback summarized by `@Amanieu` in https://github.com/rust-lang/rust/issues/96024#issuecomment-1554773172
The specific items this PR addresses so far are:
> We feel that the names "demand" and "request" are somewhat synonymous and would like only one of those to be used for better consistency.
I went with `Request` here since it sounds nicer, but I'm mildly concerned that at first glance it could be confused with the use of the word in networking context.
> The Provider trait should be deleted and its functionality should be merged into Error. We are happy to only provide an API that is only usable with Error. If there is demand for other uses then this can be provided through an external crate.
The net impact this PR has is that examples which previously looked like
```
core::any::request_ref::<String>(&err).unwramp()
```
now look like
```
(&err as &dyn core::error::Error).request_value::<String>().unwrap()
```
These are methods that based on the type hint when called return an `Option<T>` of that type. I'll admit I don't fully understand how that's done, but it involves `core::any::tags::Type` and `core::any::TaggedOption`, neither of which are exposed in the public API, to construct a `Request` which is then passed to the `Error.provide` method.
Something that I'm curious about is whether or not they are essential to the use of `Request` types (prior to this PR referred to as `Demand`) and if so does the fact that they are kept private imply that `Request`s are only meant to be constructed privately within the standard library? That's what it looks like to me.
These methods ultimately call into code that looks like:
```
/// Request a specific value by tag from the `Error`.
fn request_by_type_tag<'a, I>(err: &'a (impl Error + ?Sized)) -> Option<I::Reified>
where
I: tags::Type<'a>,
{
let mut tagged = core::any::TaggedOption::<'a, I>(None);
err.provide(tagged.as_request());
tagged.0
}
```
As far as the `Request` API is concerned, one suggestion I would like to make is that the previous example should look more like this:
```
/// Request a specific value by tag from the `Error`.
fn request_by_type_tag<'a, I>(err: &'a (impl Error + ?Sized)) -> Option<I::Reified>
where
I: tags::Type<'a>,
{
let tagged_request = core::any::Request<I>::new_tagged();
err.provide(tagged_request);
tagged.0
}
```
This makes it possible for anyone to construct a `Request` for use in their own projects without exposing an implementation detail like `TaggedOption` in the API surface.
Otherwise noteworthy is that I had to add `pub(crate)` on both `core::any::TaggedOption` and `core::any::tags` since `Request`s now need to be constructed in the `core::error` module. I considered moving `TaggedOption` into the `core::error` module but again I figured it's an implementation detail of `Request` and belongs closer to that.
At the time I am opening this PR, I have not yet looked into the following bit of feedback:
> We took a look at the generated code and found that LLVM is unable to optimize multiple .provide_* calls into a switch table because each call fetches the type id from Erased::type_id separately each time and the compiler doesn't know that these calls all return the same value. This should be fixed.
This is what I'll focus on next while waiting for feedback on the progress so far. I suspect that learning more about the type IDs will help me understand the need for `TaggedOption` a little better.
* remove `impl Provider for Error`
* rename `Demand` to `Request`
* update docstrings to focus on the conceptual API provided by `Request`
* move `core::any::{request_ref, request_value}` functions into `core::error`
* move `core::any::tag`, `core::any::Request`, an `core::any::TaggedOption` into `core::error`
* replace `provide_any` feature name w/ `error_generic_member_access`
* move `core::error::request_{ref,value} tests into core::tests::error module
* update unit and doc tests
Add `Iterator::map_windows`
Tracking issue: #87155.
This is inherited from the old PR #82413.
Unlike #82413, this PR implements the `MapWindows` to be lazy: only when pulling from the outer iterator, `.next()` of the inner iterator will be called.
## Implementaion Steps
- [x] Implement `MapWindows` to keep the iterators' [*Laziness*](https://doc.rust-lang.org/std/iter/index.html#laziness) contract.
- [x] Fix the known bug of memory access error.
- [ ] Full specialization of iterator-related traits for `MapWindows`.
- [x] `Iterator::size_hint`,
- [x] ~`Iterator::count`~,
- [x] `ExactSizeIterator` (when `I: ExactSizeIterator`),
- [x] ~`TrustedLen` (when `I: TrustedLen`)~,
- [x] `FusedIterator`,
- [x] ~`Iterator::advance_by`~,
- [x] ~`Iterator::nth`~,
- [ ] ...
- [ ] More tests and docs.
## Unresolved Questions:
- [ ] Is there any more iterator-related traits should be specialized?
- [ ] Is the double-space buffer worth?
- [ ] Should there be `rmap_windows` or something else?
- [ ] Taking GAT for consideration, should the mapper function be `FnMut(&[I::Item; N]) -> R` or something like `FnMut(ArrayView<'_, I::Item, N>) -> R`? Where `ArrayView` is mentioned in https://github.com/rust-lang/generic-associated-types-initiative/issues/2.
- It can save memory, only the same size as the array window is needed,
- It is more efficient, which requires less data copies,
- It is possibly compatible with the GATified version of `LendingIterator::windows`.
- But it prevents the array pattern matching like `iter.map_windows(|_arr: [_; N]| ())`, unless we extend the array pattern to allow matching the `ArrayView`.
Tell LLVM that the negation in `<*const T>::sub` cannot overflow
Today it's just `sub` <https://rust.godbolt.org/z/8EzEPnMr5>; with this PR it's `sub nsw`.
This is inherited from the old PR.
This method returns an iterator over mapped windows of the starting
iterator. Adding the more straight-forward `Iterator::windows` is not
easily possible right now as the items are stored in the iterator type,
meaning the `next` call would return references to `self`. This is not
allowed by the current `Iterator` trait design. This might change once
GATs have landed.
The idea has been brought up by @m-ou-se here:
https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Iterator.3A.3A.7Bpairwise.2C.20windows.7D/near/224587771
Co-authored-by: Lukas Kalbertodt <lukas.kalbertodt@gmail.com>
The `debug_assert_matches` macro was marked with the `#[macro_export]` attribute,
despite being a declarative macro/macro 2.0, for which the exporting rules are similar
to items. In fact, `#[macro_export]` on a decl macro has no effect on its visibility.
Add a new `compare_bytes` intrinsic instead of calling `memcmp` directly
As discussed in #113435, this lets the backends be the place that can have the "don't call the function if n == 0" logic, if it's needed for the target. (I didn't actually *add* those checks, though, since as I understood it we didn't actually need them on known targets?)
Doing this also let me make it `const` (unstable), which I don't think `extern "C" fn memcmp` can be.
cc `@RalfJung` `@Amanieu`
Optimize `Iterator` implementation for `&mut impl Iterator + Sized`
This adds a specialization trait to forward `fold`, `try_fold`,... to the inner iterator where possible
Add `internal_features` lint
Implements https://github.com/rust-lang/compiler-team/issues/596
Also requires some more test blessing for codegen tests etc
`@jyn514` had the idea of just `allow`ing the lint by default in the test suite. I'm not sure whether this is a good idea, but it's definitely one worth considering. Additional input encouraged.
Expand, rename and improve `incorrect_fn_null_checks` lint
This PR,
- firstly, expand the lint by now linting on references
- secondly, it renames the lint `incorrect_fn_null_checks` -> `useless_ptr_null_checks`
- and thirdly it improves the lint by catching `ptr::from_mut`, `ptr::from_ref`, as well as `<*mut _>::cast` and `<*const _>::cast_mut`
Fixes https://github.com/rust-lang/rust/issues/113601
cc ```@est31```
It lints against features that are inteded to be internal to the
compiler and standard library. Implements MCP #596.
We allow `internal_features` in the standard library and compiler as those
use many features and this _is_ the standard library from the "internal to the compiler and
standard library" after all.
Marking some features as internal wasn't exactly the most scientific approach, I just marked some
mostly obvious features. While there is a categorization in the macro,
it's not very well upheld (should probably be fixed in another PR).
We always pass `-Ainternal_features` in the testsuite
About 400 UI tests and several other tests use internal features.
Instead of throwing the attribute on each one, just always allow them.
There's nothing wrong with testing internal features^^
Clarify documentation for `CStr`
* Better differentiate summaries for `from_bytes_until_nul` and `from_bytes_with_nul`
* Add some links where they may be helpful
Improve `invalid_reference_casting` lint
This PR is a follow-up to https://github.com/rust-lang/rust/pull/111567 and https://github.com/rust-lang/rust/pull/113422.
This PR does multiple things:
- First it adds support for deferred de-reference, the goal is to support code like this, where the casting and de-reference are not done on the same expression
```rust
let myself = self as *const Self as *mut Self;
*myself = Self::Ready(value);
```
- Second it does not lint anymore on SB/TB UB code by only checking assignments (`=`, `+=`, ...) and creation of mutable references `&mut *`
- Thirdly it greatly improves the diagnostics in particular for cast from `&mut` to `&mut` or assignments
- ~~And lastly it renames the lint from `cast_ref_to_mut` to `invalid_reference_casting` which is more consistent with the ["rules"](https://github.com/rust-lang/rust-clippy/issues/2845) and also more consistent with what the lint checks~~ *https://github.com/rust-lang/rust/pull/113422*
This PR is best reviewed commit by commit.
r? compiler
Change default panic handler message format.
This changes the default panic hook's message format from:
```
thread '{thread}' panicked at '{message}', {location}
```
to
```
thread '{thread}' panicked at {location}:
{message}
```
This puts the message on its own line without surrounding quotes, making it easiser to read. For example:
Before:
```
thread 'main' panicked at 'env variable `IMPORTANT_PATH` should be set by `wrapper_script.sh`', src/main.rs:4:6
```
After:
```
thread 'main' panicked at src/main.rs:4:6:
env variable `IMPORTANT_PATH` should be set by `wrapper_script.sh`
```
---
See this PR by `@nyurik,` which does that for only multi-line messages (specifically because of `assert_eq`): https://github.com/rust-lang/rust/pull/111071
This is the change that does that for *all* panic messages.
Make `Debug` representations of `[Lazy, Once]*[Cell, Lock]` consistent with `Mutex` and `RwLock`
`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`.
