improve panic message for slice windows and chunks
before:
```text
thread 'main' panicked at 'size is zero', /rustc/1e225413a21fa69570bd3fefea9eb05e33f8b917/library/core/src/slice/mod.rs:809:44
```
```text
thread 'main' panicked at 'assertion failed: `(left != right)`
left: `0`,
right: `0`: chunks cannot have a size of zero', /rustc/1e225413a21fa69570bd3fefea9eb05e33f8b917/library/core/src/slice/mod.rs:843:9
```
after:
```text
thread 'main' panicked at 'chunk size must be non-zero', src/main.rs:4:22
```
fixes https://github.com/rust-lang/rust/issues/107437
Fixing confusion between mod and remainder
Like many programming languages, rust too confuses remainder and modulus. The `%` operator and the associated `Rem` trait is (as the trait name suggests) the remainder, but since most people are linguistically more familiar with the modulus the documentation sometimes claims otherwise. This PR tries to fix this problem in rustc.
Bump bootstrap compiler to 1.68
This also changes our stage0.json to include the rustc component for the rustfmt pinned nightly toolchain, which is currently necessary due to rustfmt dynamically linking to that toolchain's librustc_driver and libstd.
r? `@pietroalbini`
Remove `GenFuture` from core
The handling of async constructs in the compiler does not rely on `GenFuture` anymore since `1.67`, so this code can now be removed from `core`.
Implement `signum` with `Ord`
Rather than needing to do things like #105840 for `signum` too, might as well just implement that method using `Ord`, since it's doing the same "I need `-1`/`0`/`+1`" behaviour that `cmp` is already doing.
This also seems to slightly improve the assembly: <https://rust.godbolt.org/z/5oEEqbxK1>
Skip possible where_clause_object_safety lints when checking `multiple_supertrait_upcastable`
Fix#106247
To achieve this, I lifted the `WhereClauseReferencesSelf` out from `object_safety_violations` and move it into `is_object_safe` (which is changed to a new query).
cc `@dtolnay`
r? `@compiler-errors`
Remove `ControlFlow::{BREAK, CONTINUE}`
Libs-API decided to remove these in #102697.
Follow-up to #107023, which removed them from `compiler/`, but a couple new ones showed up since that was merged.
r? libs
Libs-API decided to remove these in #102697.
Follow-up to #107023, which removed them from `compiler/`, but a couple new ones showed up since that was merged.
core: Support variety of atomic widths in width-agnostic functions
Before this change, the following functions and macros were annotated with `#[cfg(target_has_atomic = "8")]` or
`#[cfg(target_has_atomic_load_store = "8")]`:
* `atomic_int`
* `strongest_failure_ordering`
* `atomic_swap`
* `atomic_add`
* `atomic_sub`
* `atomic_compare_exchange`
* `atomic_compare_exchange_weak`
* `atomic_and`
* `atomic_nand`
* `atomic_or`
* `atomic_xor`
* `atomic_max`
* `atomic_min`
* `atomic_umax`
* `atomic_umin`
However, none of those functions and macros actually depend on 8-bit width and they are needed for all atomic widths (16-bit, 32-bit, 64-bit etc.). Some targets might not support 8-bit atomics (i.e. BPF, if we would enable atomic CAS for it).
This change fixes that by removing the `"8"` argument from annotations, which results in accepting the whole variety of widths.
Fixes#106845Fixes#106795
Signed-off-by: Michal Rostecki <vadorovsky@gmail.com>
Rollup of 8 pull requests
Successful merges:
- #106904 (Preserve split DWARF files when building archives.)
- #106971 (Handle diagnostics customization on the fluent side (for one specific diagnostic))
- #106978 (Migrate mir_build's borrow conflicts)
- #107150 (`ty::tls` cleanups)
- #107168 (Use a type-alias-impl-trait in `ObligationForest`)
- #107189 (Encode info for Adt in a single place.)
- #107322 (Custom mir: Add support for some remaining, easy to support constructs)
- #107323 (Disable ConstGoto opt in cleanup blocks)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Custom mir: Add support for some remaining, easy to support constructs
Some documentation for previous changes and support for `Deinit`, checked binops, len, and array repetition
r? ```@oli-obk``` or ```@tmiasko```
Move format_args!() into AST (and expand it during AST lowering)
Implements https://github.com/rust-lang/compiler-team/issues/541
This moves FormatArgs from rustc_builtin_macros to rustc_ast_lowering. For now, the end result is the same. But this allows for future changes to do smarter things with format_args!(). It also allows Clippy to directly access the ast::FormatArgs, making things a lot easier.
This change turns the format args types into lang items. The builtin macro used to refer to them by their path. After this change, the path is no longer relevant, making it easier to make changes in `core`.
This updates clippy to use the new language items, but this doesn't yet make clippy use the ast::FormatArgs structure that's now available. That should be done after this is merged.
impl DispatchFromDyn for Cell and UnsafeCell
After some fruitful discussion on [Internals](https://internals.rust-lang.org/t/impl-dispatchfromdyn-for-cell-2/16520) here's my first PR to rust-lang/rust 🎉
Please let me know if there's something I missed.
This adds `DispatchFromDyn` impls for `Cell`, `UnsafeCell` and `SyncUnsafeCell`.
An existing test is also expanded to test the `Cell` impl (which requires the `UnsafeCell` impl)
The different `RefCell` types can not implement `DispatchFromDyn` since they have more than one (non ZST) field.
**Edit:**
### What:
These changes allow one to make types like `MyRc`(code below), to be object safe method receivers after implementing `DispatchFromDyn` and `Deref` for them.
This allows for code like this:
```rust
struct MyRc<T: ?Sized>(Cell<NonNull<RcBox<T>>>);
/* impls for DispatchFromDyn, CoerceUnsized and Deref for MyRc*/
trait Trait {
fn foo(self: MyRc<Self>);
}
let impls_trait = ...;
let rc = MyRc::new(impls_trait) as MyRc<dyn Trait>;
rc.foo();
```
Note: `Cell` and `UnsafeCell` won't directly become valid method receivers since they don't implement `Deref`. Making use of these changes requires a wrapper type and nightly features.
### Why:
A custom pointer type with interior mutability allows one to store extra information in the pointer itself.
These changes allow for such a type to be a method receiver.
### Examples:
My use case is a cycle aware custom `Rc` implementation that when dropping a cycle marks some references dangling.
On the [forum](https://internals.rust-lang.org/t/impl-dispatchfromdyn-for-cell/14762/8) andersk mentioned that they track if a `Gc` reference is rooted with an extra bit in the reference itself.
Suggest using a lock for `*Cell: Sync` bounds
I mostly did this for `OnceCell<T>` at first because users will be confused to see that the `OnceCell<T>` in `std` isn't `Sync` but then extended it to `Cell<T>` and `RefCell<T>` as well.
`sub_ptr()` is equivalent to `usize::try_from().unwrap_unchecked()`, not `usize::from().unwrap_unchecked()`
`usize::from()` gives a `usize`, not `Result<usize>`, and `usize: From<isize>` is not implemented.
Allow fmt::Arguments::as_str() to return more Some(_).
This adjusts the documentation to allow optimization of format_args!() to be visible through fmt::Arguments::as_str().
This allows for future changes like https://github.com/rust-lang/rust/pull/106824.
Before this change, the following functions and macros were annotated
with `#[cfg(target_has_atomic = "8")]` or
`#[cfg(target_has_atomic_load_store = "8")]`:
* `atomic_int`
* `strongest_failure_ordering`
* `atomic_swap`
* `atomic_add`
* `atomic_sub`
* `atomic_compare_exchange`
* `atomic_compare_exchange_weak`
* `atomic_and`
* `atomic_nand`
* `atomic_or`
* `atomic_xor`
* `atomic_max`
* `atomic_min`
* `atomic_umax`
* `atomic_umin`
However, none of those functions and macros actually depend on 8-bit
width and they are needed for all atomic widths (16-bit, 32-bit, 64-bit
etc.). Some targets might not support 8-bit atomics (i.e. BPF, if we
would enable atomic CAS for it).
This change fixes that by removing the `"8"` argument from annotations,
which results in accepting the whole variety of widths.
Fixes#106845Fixes#106795
Signed-off-by: Michal Rostecki <vadorovsky@gmail.com>
Memory pre-fetching prefers forward scanning vs backwards scanning, and the
code-gen is usually better. For the most sensitive types such as integers, these
are planned to be merged bidirectionally at once. So there is no benefit in
scanning backwards.
The largest perf gains are seen for full ascending and descending inputs, which
see 1.5x speedups. Random inputs benefit too, and some patterns can loose out,
but these losses are minimal.
Improve the documentation of `black_box`
There don't seem to be many great resources on how `black_box` should be used, so I added some information here
Unify stable and unstable sort implementations in same core module
This moves the stable sort implementation to the core::slice::sort module. By virtue of being in core it can't access `Vec`. The two `Vec` used by merge sort, `buf` and `runs`, are modelled as custom types that implement the very limited required `Vec` interface with the help of provided allocation and free functions. This is done to allow future re-use of functions and logic between stable and unstable sort. Such as `insert_head`.
This is in preparation of #100856 and #104116. It only moves code, it *doesn't* change any of the sort related logic. This unlocks the ability to share `insert_head`, `insert_tail`, `swap_if_less` `merge` and more.
Tagging ````@Mark-Simulacrum```` I hope this allows progress on #100856, by moving `merge_sort` here I hope future changes will be easier to review.
- Eliminates all the `get_context` calls that async lowering created.
- Replace all `Local` `ResumeTy` types with `&mut Context<'_>`.
The `Local`s that have their types replaced are:
- The `resume` argument itself.
- The argument to `get_context`.
- The yielded value of a `yield`.
The `ResumeTy` hides a `&mut Context<'_>` behind an unsafe raw pointer, and the
`get_context` function is being used to convert that back to a `&mut Context<'_>`.
Ideally the async lowering would not use the `ResumeTy`/`get_context` indirection,
but rather directly use `&mut Context<'_>`, however that would currently
lead to higher-kinded lifetime errors.
See <https://github.com/rust-lang/rust/issues/105501>.
The async lowering step and the type / lifetime inference / checking are
still using the `ResumeTy` indirection for the time being, and that indirection
is removed here. After this transform, the generator body only knows about `&mut Context<'_>`.
Lift `T: Sized` bounds from some `strict_provenance` pointer methods
This PR removes requirement for `T` (pointee type) to be `Sized` to call `pointer::{addr, expose_addr, with_addr, map_addr}`. These functions don't use `T`'s size, so there is no reason for them to require this. Updated public API:
cc ``@Gankra,`` #95228
r? libs-api
Add heapsort fallback in `select_nth_unstable`
Addresses #102451 and #106933.
`slice::select_nth_unstable` uses a quick select implementation based on the same pattern defeating quicksort algorithm that `slice::sort_unstable` uses. `slice::sort_unstable` uses a recursion limit and falls back to heapsort if there were too many bad pivot choices, to ensure O(n log n) worst case running time (known as introsort). However, `slice::select_nth_unstable` does not have such a fallback strategy, which leads to it having a worst case running time of O(n²) instead. #102451 links to a playground which generates pathological inputs that show this quadratic behavior. On my machine, a randomly generated slice of length `1 << 19` takes ~200µs to calculate its median, whereas a pathological input of the same length takes over 2.5s. This PR adds an iteration limit to `select_nth_unstable`, falling back to heapsort, which ensures an O(n log n) worst case running time (introselect). With this change, there was no noticable slowdown for the random input, but the same pathological input now takes only ~1.2ms. In the future it might be worth implementing something like Median of Medians or Fast Deterministic Selection instead, which guarantee O(n) running time for all possible inputs. I've left this as a `FIXME` for now and only implemented the heapsort fallback to minimize the needed code changes.
I still think we should clarify in the `select_nth_unstable` docs that the worst case running time isn't currently O(n) (the original reason that #102451 was opened), but I think it's a lot better to be able to guarantee O(n log n) instead of O(n²) for the worst case.
Remove various double spaces in the libraries.
I was just pretty bothered by this when reading the source for a function, and was suggested to check if this happened elsewhere.
reword Option::as_ref and Option::map examples
The description for the examples of `Option::as_ref` and `Option::map` imply that the example is only doing type conversion, when it is actually finding the length of a string.
Changes the wording to imply that some operation is being run on the value contained in the `Option`
closes#104476
Stabilize `::{core,std}::pin::pin!`
As discussed [over here](https://github.com/rust-lang/rust/issues/93178#issuecomment-1295843548), it looks like a decent time to stabilize the `pin!` macro.
### Public API
```rust
// in module `core::pin`
/// API: `fn pin<T>($value: T) -> Pin<&'local mut T>`
pub macro pin($value:expr $(,)?) {
…
}
```
- Tracking issue: #93178
(now all this needs is an FCP by the proper team?)
doc: rewrite doc for signed int::{carrying_add,borrowing_sub}
Reword the documentation for bigint helper methods, signed `int::{carrying_add,borrowing_sub}` (#85532).
This change is a follow-up to #101889, which was for the unsigned methods.
Don't derive Debug for `OnceWith` & `RepeatWith`
Closures don't impl Debug, so the derived impl is kinda useless. The behavior of not debug-printing closures is consistent with the rest of the iterator adapters/sources.
Update `rand` in the stdlib tests, and remove the `getrandom` feature from it.
The main goal is actually removing `getrandom`, so that eventually we can allow running the stdlib test suite on tier3 targets which don't have `getrandom` support. Currently those targets can only run the subset of stdlib tests that exist in uitests, and (generally speaking), we prefer not to test libstd functionality in uitests, which came up recently in https://github.com/rust-lang/rust/pull/104095 and https://github.com/rust-lang/rust/pull/104185. Additionally, the fact that we can't update `rand`/`getrandom` means we're stuck with the old set of tier3 targets, so can't test new ones.
~~Anyway, I haven't checked that this actually does allow use on tier3 targets (I think it does not, as some work is needed in stdlib submodules) but it moves us slightly closer to this, and seems to allow at least finally updating our `rand` dep, which definitely improves the status quo.~~ Checked and works now.
For the most part, our tests and benchmarks are fine using hard-coded seeds. A couple tests seem to fail with this (stuff manipulating the environment expecting no collisions, for example), or become pointless (all inputs to a function become equivalent). In these cases I've done a (gross) dance (ab)using `RandomState` and `Location::caller()` for some extra "entropy".
Trying to share that code seems *way* more painful than it's worth given that the duplication is a 7-line function, even if the lines are quite gross. (Keeping in mind that sharing it would require adding `rand` as a non-dev dep to std, and exposing a type from it publicly, all of which sounds truly awful, even if done behind a perma-unstable feature).
See also some previous attempts:
- https://github.com/rust-lang/rust/pull/86963 (in particular https://github.com/rust-lang/rust/pull/86963#issuecomment-885438936 which explains why this is non-trivial)
- https://github.com/rust-lang/rust/pull/89131
- https://github.com/rust-lang/rust/pull/96626#issuecomment-1114562857 (I tried in that PR at the same time, but settled for just removing the usage of `thread_rng()` from the benchmarks, since that was the main goal).
- https://github.com/rust-lang/rust/pull/104185
- Probably more. It's very tempting of a thing to "just update".
r? `@Mark-Simulacrum`
Suggest `impl Fn*` and `impl Future` in `-> _` return suggestions
Follow-up to #106172, only the last commit is relevant. Can rebase once that PR is landed for easier review.
Suggests `impl Future` and `impl Fn{,Mut,Once}` in `-> _` return suggestions.
r? `@estebank`
default OOM handler: use non-unwinding panic, to match std handler
The OOM handler in std will by default abort. This adjusts the default in liballoc to do the same, using the `can_unwind` flag on the panic info to indicate a non-unwinding panic.
In practice this probably makes little difference since the liballoc default will only come into play in no-std situations where people write a custom panic handler, which most likely will not implement unwinding. But still, this seems more consistent.
Cc `@rust-lang/wg-allocators,` https://github.com/rust-lang/rust/issues/66741
`Split*::as_str` refactor
I've made this patch almost a year ago, so the rename and the behavior change are in one commit, sorry 😅
This fixes#84974, as it's required to make other changes work.
This PR
- Renames `as_str` method of string `Split*` iterators to `remainder` (it seems like the `as_str` name was confusing to users)
- Makes `remainder` return `Option<&str>`, to distinguish between "the iterator is exhausted" and "the tail is empty", this was [required on the tracking issue](https://github.com/rust-lang/rust/issues/77998#issuecomment-832696619)
r? `@m-ou-se`
Context is no longer Sync so this doesn't work.
error[E0277]: `*mut ()` cannot be shared between threads safely
--> library/core/tests/task.rs:24:21
|
24 | static CONTEXT: Context<'static> = Context::from_waker(&WAKER);
| ^^^^^^^^^^^^^^^^ `*mut ()` cannot be shared between threads safely
|
= help: within `Context<'static>`, the trait `Sync` is not implemented for `*mut ()`
= note: required because it appears within the type `PhantomData<*mut ()>`
= note: required because it appears within the type `Context<'static>`
= note: shared static variables must have a type that implements `Sync`
Revert "Implement allow-by-default `multiple_supertrait_upcastable` lint"
This is a clean revert of #105484.
I confirmed that reverting that PR fixes the regression reported in #106247. ~~I can't say I understand what this code is doing, but maybe it can be re-landed with a different implementation.~~ **Edit:** https://github.com/rust-lang/rust/issues/106247#issuecomment-1367174384 has an explanation of why #105484 ends up surfacing spurious `where_clause_object_safety` errors. The implementation of `where_clause_object_safety` assumes we only check whether a trait is object safe when somebody actually uses that trait with `dyn`. However the implementation of `multiple_supertrait_upcastable` added in the problematic PR involves checking *every* trait for whether it is object-safe.
FYI `@nbdd0121` `@compiler-errors`
Add #[inline] markers to once_cell methods
Added inline markers to all simple methods under the `once_cell` feature. Relates to #74465 and #105587
This should not block #105587
Replace libstd, libcore, liballoc terminology in docs
Fixes#103551. I changed line comments containing the outdated terms as well.
It would be great if someone with more experience could weigh in on whether these changes introduce ambiguity as suggested in https://github.com/rust-lang/rust/issues/103551#issuecomment-1291225315.
doc: clearer and more correct Iterator::scan
The `Iterator::scan` documentation seemed a little misleading to my newcomer
eyes, and this tries to address that.
* I found “similar to `fold`” unhelpful because (a) the similarity is only that
they maintain state between iterations, and (b) the _dissimilarity_ is no less
important: one returns a final value and the other an iterator. So this
replaces that with “which, like `fold`, holds internal state, but unlike
`fold`, produces a new iterator.
* I found “the return value from the closure, an `Option`, is yielded by the
iterator” to be downright incorrect, because “yielded by the iterator” means
“returned by the `next` method wrapped in `Some`”, so this implied that `scan`
would convert an input iterator of `T` to an output iterator of `Option<T>`.
So this replaces “yielded by the iterator” with “returned by the `next`
method” and elaborates: “Thus the closure can return `Some(value)` to yield
`value`, or `None` to end the iteration.”
* This also changes the example to illustrate the latter point by returning
`None` to terminate the iteration early based on `state`.
Bump master bootstrap compiler
This PR bumps the bootstrap compiler to the beta created earlier this week, cherry-picks the stabilization version number updates, and updates the `cfg(bootstrap)`s.
r? `@Mark-Simulacrum`
Implement allow-by-default `multiple_supertrait_upcastable` lint
The lint detects when an object-safe trait has multiple supertraits.
Enabled in libcore and liballoc as they are low-level enough that many embedded programs will use them.
r? `@nikomatsakis`
Clarify docs of `RefCell`
Comparison operators only panic if the `RefCell` is mutably borrowed, and `RefCell::swap()` can also panic if swapping a `RefCell` with itself.
Fix UnsafeCell Documentation Spelling Error
This fixes the spelling of "deallocated" (instead of the original "deallocted") In the `cell.rs` source file. Honestly probably not worth the time to evaluate, but since it doesn't involve any code change, I figure why not?
Fix a formatting error in Iterator::for_each docs
There is a formatting error (extra space in an assignment) in the documentation of `core::iter::Iterator::for_each`, which I have fixed in this pull request.
More inference-friendly API for lazy
The signature for new was
```
fn new<F>(f: F) -> Lazy<T, F>
```
Notably, with `F` unconstrained, `T` can be literally anything, and just `let _ = Lazy::new(|| 92)` would not typecheck.
This historiacally was a necessity -- `new` is a `const` function, it couldn't have any bounds. Today though, we can move `new` under the `F: FnOnce() -> T` bound, which gives the compiler enough data to infer the type of T from closure.
abort immediately on bad mem::zeroed/uninit
Now that we have non-unwinding panics, let's use them for these assertions. This re-establishes the property that `mem::uninitialized` and `mem::zeroed` will never unwind -- the earlier approach of causing panics here sometimes led to hard-to-debug segfaults when the surrounding code was not able to cope with the unexpected unwinding.
Cc `@bjorn3` I did not touch cranelift but I assume it needs a similar patch. However it has a `codegen_panic` abstraction that I did not want to touch since I didn't know how else it is used.
add ptr::from_{ref,mut}
We have methods to avoid almost all `as` casts around raw pointer handling, except for the initial cast from reference to raw pointer. These new methods close that gap.
(I also moved `null_mut` next to `null` to keep the file consistently organized.)
r? libs-api
Tracking issue: https://github.com/rust-lang/rust/issues/106116
According to Godbolt¹, on x86_64 using binary and produces slightly
better code than using subtraction. Readability of both is pretty
much equivalent so might just as well use the shorter option.
¹ https://rust.godbolt.org/z/9jM3ejbMx
Rollup of 8 pull requests
Successful merges:
- #105584 (add assert messages if chunks/windows are length 0)
- #105602 (interpret: add read_machine_[ui]size convenience methods)
- #105824 (str.lines() docstring: clarify that line endings are not returned)
- #105980 (Refer to "Waker" rather than "RawWaker" in `drop` comment)
- #105986 (Fix typo in reading_half_a_pointer.rs)
- #105995 (Add regression test for #96530)
- #106008 (Sort lint_groups in no_lint_suggestion)
- #106014 (Add comment explaining what the scrape-examples-toggle.goml GUI test is about)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Clarify that raw retags are not permitted in Mir
Not sure when this changed, but documentation and the validator needed to be updated. This also removes raw retags from custom mir.
cc rust-lang/miri#2735
r? `@RalfJung`
Refer to "Waker" rather than "RawWaker" in `drop` comment
In my view this is technically more correct as `Waker` actually implements `Drop` (which calls the `drop` method) whereas `RawWaker` does not.
str.lines() docstring: clarify that line endings are not returned
Previously, the str.lines() docstring stated that lines are split at line endings, but not whether those were returned or not. This new version of the docstring states this explicitly, avoiding the need of getting to doctests to get an answer to this FAQ.
Rename `assert_uninit_valid` intrinsic
It's not about "uninit" anymore but about "filling with 0x01 bytes" so the name should at least try to reflect that.
This is actually not fully correct though, as it does still panic for all uninit with `-Zstrict-init-checks`. I'm not sure what the best way is to deal with that not causing confusion. I guess we could just remove the flag? I don't think having it makes a lot of sense anymore with the direction that we have chose to go. It could be relevant again if #100423 lands so removing it may be a bit over eager.
r? `@RalfJung`
Implement `From<bool>` for f32, f64
As is required for trait implementations, these are insta-stable. Given there is a release tomorrow and this needs FCP, I set 1.65 as the stable version.
`@rustbot` label +A-floating-point +C-feature-request +needs-fcp +relnotes +S-waiting-on-review +T-libs-api -T-libs
Implement va_list and va_arg for s390x FFI
Following the s390x ELF ABI and based on the clang implementation, provide appropriate definitions of va_list in library/core/src/ffi/mod.rs and va_arg handling in compiler/rustc_codegen_llvm/src/va_arg.rs.
Fixes the following test cases on s390x:
src/test/run-make-fulldeps/c-link-to-rust-va-list-fn src/test/ui/abi/variadic-ffi.rs
Fixes https://github.com/rust-lang/rust/issues/84628.
Following the s390x ELF ABI and based on the clang implementation,
provide appropriate definitions of va_list in library/core/src/ffi/mod.rs
and va_arg handling in compiler/rustc_codegen_llvm/src/va_arg.rs.
Fixes the following test cases on s390x:
src/test/run-make-fulldeps/c-link-to-rust-va-list-fn
src/test/ui/abi/variadic-ffi.rs
Fixes https://github.com/rust-lang/rust/issues/84628.
Revert "Replace usage of `ResumeTy` in async lowering with `Context`"
Reverts rust-lang/rust#105250
Fixes: #105501
Following instructions from [forge](https://forge.rust-lang.org/compiler/reviews.html#reverts).
This change introduced a breaking change that is not actionable nor relevant, and is blocking updates to our toolchain. Along with other comments on the CL marking issues that are fixed by reverts, reverting is best until these issues can be resolved
cc. `@Swatinem`
Support call and drop terminators in custom mir
The only caveat with this change is that cleanup blocks are not supported. I would like to add them, but it's not quite clear to me what the best way to do that is, so I'll have to think about it some more.
r? ``@oli-obk``
Previously, the str.lines() docstring stated that lines are split at line
endings, but not whether those were returned or not. This new version of the
docstring states this explicitly, avoiding the need of getting to doctests to
get an answer to this FAQ.
This commit
- Renames `Split*::{as_str -> remainder}` as it seems less confusing
- Makes `remainder` return Option<&str> to distinguish between
"iterator is exhausted" and "the tail is empty"
doc: Fix a few small issues
Hey, while reading through the (awesome) stdlib docs, I found a few minor typos.
* A few typos around generic types (`;` vs `,`)
* Use inline code formatting for code fragments
* One instance of wrong wording
Custom MIR: Many more improvements
Commits are each atomic changes, best reviewed one at a time, with the exception that the last commit includes all the documentation.
### First commit
Unsafetyck was not correctly disabled before for `dialect = "built"` custom MIR. This is fixed and a regression test is added.
### Second commit
Implements `Discriminant`, `SetDiscriminant`, and `SwitchInt`.
### Third commit
Implements indexing, field, and variant projections.
### Fourth commit
Documents the previous commits and everything else.
There is some amount of weirdness here due to having to beat Rust syntax into cooperating with MIR concepts, but it hopefully should not be too much. All of it is documented.
r? `@oli-obk`
Use rint intrinsic instead of roundeven to impement `round_ties_even`. They do the same thing when rounding mode is default, which Rust assumes.
And `rint` has better platform support.
Keeps `roundeven` around in `core::intrinsics`, it's doing no harm there.
Remove wrong note for short circuiting operators
They *are* representable by traits, even if the short-circuiting behaviour requires a different approach than the non-short-circuiting operators. For an example proposal, see the postponed [RFC 2722](https://github.com/rust-lang/rfcs/pull/2722). As it is not accurate, remove most of the note.
They *are* representable by traits, even if the short-circuiting
behaviour requires a different approach than the non-short-circuiting
operators. For an example proposal, see the postponed RFC 2722.
As it is not accurate, reword the note.
attempt to clarify align_to docs
This is not intended the change the docs at all, but `@workingjubilee` said the current docs are incomprehensible to some people so this is an attempt to fix that. No idea if it helps, so -- feedback welcome.
(Please let's not use this to discuss *changing* the spec. Whoever wants to change the spec should please make a separate PR for that.)
Replace usage of `ResumeTy` in async lowering with `Context`
Replaces using `ResumeTy` / `get_context` in favor of using `&'static mut Context<'_>`.
Usage of the `'static` lifetime here is technically "cheating", and replaces the raw pointer in `ResumeTy` and the `get_context` fn that pulls the correct lifetimes out of thin air.
fixes https://github.com/rust-lang/rust/issues/104828 and https://github.com/rust-lang/rust/pull/104321#issuecomment-1336363077
r? `@oli-obk`
Replaces using `ResumeTy` / `get_context` in favor of using `&'static mut Context<'_>`.
Usage of the `'static` lifetime here is technically "cheating", and replaces
the raw pointer in `ResumeTy` and the `get_context` fn that pulls the
correct lifetimes out of thin air.
PartialEq: PERs are homogeneous
PartialEq claims that it corresponds to a PER, but that is only a well-defined statement when `Rhs == Self`. There is no standard notion of PER on a relation between two different sets/types. So move this out of the first paragraph and clarify this.
Adjust inlining attributes around panic_immediate_abort
The goal of `panic_immediate_abort` is to permit the panic runtime and formatting code paths to be optimized away. But while poking through some disassembly of a small program compiled with that option, I found that was not the case. Enabling LTO did address that specific issue, but enabling LTO is a steep price to pay for this feature doing its job.
This PR fixes that, by tweaking two things:
* All the slice indexing functions that we `const_eval_select` on get `#[inline]`. `objdump -dC` told me that originally some `_ct` functions could end up in an executable. I won't pretend to understand what's going on there.
* Normalize attributes across all `panic!` wrappers: use `inline(never) + cold` normally, and `inline` when `panic_immediate_abort` is enabled.
But also, with LTO and `panic_immediate_abort` enabled, this patch knocks ~709 kB out of the `.text` segment of `librustc_driver.so`. That is slightly surprising to me, my best theory is that this shifts some inlining earlier in compilation, enabling some subsequent optimizations. The size improvement of `librustc_driver.so` with `panic_immediate_abort` due to this patch is greater with LTO than without LTO, which I suppose backs up this theory.
I do not know how to test this. I would quite like to, because I think what this is solving was an accidental regression. This only works with `-Zbuild-std` which is a cargo flag, and thus can't be used in a rustc codegen test.
r? `@thomcc`
---
I do not seriously think anyone is going to use a compiler built with `panic_immediate_abort`, but I wanted a big complicated Rust program to try this out on, and the compiler is such.
Add `type_ascribe!` macro as placeholder syntax for type ascription
This makes it still possible to test the internal semantics of type ascription even once the `:`-syntax is removed from the parser. The macro now gets used in a bunch of UI tests that test the semantics and not syntax of type ascription.
I might have forgotten a few tests but this should hopefully be most of them. The remaining ones will certainly be found once type ascription is removed from the parser altogether.
Part of #101728
`#![custom_mir]`: Various improvements
This PR makes a bunch of improvements to `#![custom_mir]`. Ideally this would be 4 PRs, one for each commit, but those would take forever to get merged and be a pain to juggle. Should still be reviewed one commit at a time though.
### Commit 1: Support arbitrary `let`
Before this change, all locals used in the body need to be declared at the top of the `mir!` invocation, which is rather annoying. We attempt to change that.
Unfortunately, we still have the requirement that the output of the `mir!` macro must resolve, typecheck, etc. Because of that, we can't just accept this in the THIR -> MIR parser because something like
```rust
{
let x = 0;
Goto(other)
}
other = {
RET = x;
Return()
}
```
will fail to resolve. Instead, the implementation does macro shenanigans to find the let declarations and extract them as part of the `mir!` macro. That *works*, but it is fairly complicated and degrades debuginfo by quite a bit. Specifically, the spans for any statements and declarations that are affected by this are completely wrong. My guess is that this is a net improvement though.
One way to recover some of the debuginfo would be to not support type annotations in the `let` statements, which would allow us to parse like `let $stmt:stmt`. That seems quite surprising though.
### Commit 2: Parse consts
Reuses most of the const parsing from regular Mir building for building custom mir
### Commit 3: Parse statics
Statics are slightly weird because the Mir primitive associated with them is a reference/pointer to them, so this is factored out separately.
### Commit 4: Fix some spans
A bunch of the spans were non-ideal, so we adjust them to be much more helpful.
r? `@oli-obk`
Add slice to the stack allocated string comment
Precise that the "stack allocated string" is not a string but a string slice.
``@rustbot`` label +A-docs
Stop peeling the last iteration of the loop in `Vec::resize_with`
`resize_with` uses the `ExtendWith` code that peels the last iteration:
341d8b8a2c/library/alloc/src/vec/mod.rs (L2525-L2529)
But that's kinda weird for `ExtendFunc` because it does the same thing on the last iteration anyway:
341d8b8a2c/library/alloc/src/vec/mod.rs (L2494-L2502)
So this just has it use the normal `extend`-from-`TrustedLen` code instead.
r? `@ghost`
Manually implement PartialEq for Option<T> and specialize non-nullable types
This PR manually implements `PartialEq` and `StructuralPartialEq` for `Option`, which seems to produce slightly better codegen than the automatically derived implementation.
It also allows specializing on the `core::num::NonZero*` and `core::ptr::NonNull` types, taking advantage of the niche optimization by transmuting the `Option<T>` to `T` to be compared directly, which can be done in just two instructions.
A comparison of the original, new and specialized code generation is available [here](https://godbolt.org/z/dE4jxdYsa).
