Rename `optin_builtin_traits` to `auto_traits`
They were originally called "opt-in, built-in traits" (OIBITs), but
people realized that the name was too confusing and a mouthful, and so
they were renamed to just "auto traits". The feature flag's name wasn't
updated, though, so that's what this PR does.
There are some other spots in the compiler that still refer to OIBITs,
but I don't think changing those now is worth it since they are internal
and not particularly relevant to this PR.
Also see <https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/opt-in.2C.20built-in.20traits.20(auto.20traits).20feature.20name>.
r? `@oli-obk` (feel free to re-assign if you're not the right reviewer for this)
They were originally called "opt-in, built-in traits" (OIBITs), but
people realized that the name was too confusing and a mouthful, and so
they were renamed to just "auto traits". The feature flag's name wasn't
updated, though, so that's what this PR does.
There are some other spots in the compiler that still refer to OIBITs,
but I don't think changing those now is worth it since they are internal
and not particularly relevant to this PR.
Also see <https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/opt-in.2C.20built-in.20traits.20(auto.20traits).20feature.20name>.
Rollup of 10 pull requests
Successful merges:
- #76829 (stabilize const_int_pow)
- #79080 (MIR visitor: Don't treat debuginfo field access as a use of the struct)
- #79236 (const_generics: assert resolve hack causes an error)
- #79287 (Allow using generic trait methods in `const fn`)
- #79324 (Use Option::and_then instead of open-coding it)
- #79325 (Reduce boilerplate with the `?` operator)
- #79330 (Fix typo in comment)
- #79333 (doc typo)
- #79337 (Use Option::map instead of open coding it)
- #79343 (Add my (`@flip1995)` work mail to the mailmap)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Change slice::to_vec to not use extend_from_slice
I saw this [Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/String.3A.3Afrom%28.26str%29.20wonky.20codegen/near/216164455), and didn't see any update from it, so I thought I'd try to fix it. This converts `to_vec` to no longer use `extend_from_slice`, but relies on knowing that the allocated capacity is the same size as the input.
[Godbolt new v1](https://rust.godbolt.org/z/1bcWKG)
[Godbolt new v2 w/ drop guard](https://rust.godbolt.org/z/5jn76K)
[Godbolt old version](https://rust.godbolt.org/z/e4ePav)
After some amount of iteration, there are now two specializations for `to_vec`, one for `Copy` types that use memcpy, and one for clone types which is the original from this PR.
This is then used inside of `impl<T: Clone> FromIterator<Iter::Slice<T>> for Vec<T>` which is essentially equivalent to `&[T] -> Vec<T>`, instead of previous specialization of the `extend` function. This is because extend has to reason more about existing capacity by calling `reserve` on an existing vec, and thus produces worse asm.
Downsides: This allocates the exact capacity, so I think if many items are added to this `Vec` after, it might need to allocate whereas extending may not. I also noticed the number of faults went up in the benchmarks, but not sure where from exactly.
This also required adding a loop guard in case clone panics
Add specialization for copy
There is a better version for copy, so I've added specialization for that function
and hopefully that should speed it up even more.
Switch FromIter<slice::Iter> to use `to_vec`
Test different unrolling version for to_vec
Revert to impl
From benchmarking, it appears this version is faster
BTreeMap: swap the names of NodeRef::new and Root::new_leaf
#78104 preserved the name of Root::new_leaf to minimize changes, but the resulting names are confusing.
r? `@Mark-Simulacrum`
BTreeMap: address namespace conflicts
Fix an annoyance popping up whenever synchronizing the test cases with a version capable of miri-track-raw-pointers.
r? `@Mark-Simulacrum`
More consistently use spaces after commas in lists in docs
This PR changes instances of lists that didn't use spaces after commas, like `vec![1,2,3]`, to `vec![1, 2, 3]` to be more consistent with idiomatic Rust style (the way these were looks strange to me, especially because there are often lists that *do* use spaces after the commas later in the same code block 😬).
I noticed one of these in an example in the stdlib docs and went looking for more, but as far as I can see, I'm only changing those spots in user-facing documentation or rustc output, and the changes make no semantic difference.
clarify rules for ZST Boxes
LLVM's rules around `getelementptr inbounds` with offset 0 are a bit annoying, and as a consequence we have no choice but say that a `Box<()>` pointing to previously allocated memory that has since been freed is UB. Clarify the docs to reflect this.
This is based on conversations on the LLVM mailing list.
* Here's my initial mail: https://lists.llvm.org/pipermail/llvm-dev/2019-February/130452.html
* The first email of the March part of that thread: https://lists.llvm.org/pipermail/llvm-dev/2019-March/130831.html
* First email of the April part: https://lists.llvm.org/pipermail/llvm-dev/2019-April/131693.html
The conclusion for me at least was that `getelementptr inbounds` with offset 0 is *not* the identity function, but can sometimes return `poison` even when the input is a regular pointer -- specifically, it returns `poison` when this pointer points into something that LLVM "knows has been deallocated", i.e., a former LLVM-managed allocation. It is however the identity function on pointers obtained by casting integers.
Note that there [are formal proposals](https://people.mpi-sws.org/~jung/twinsem/twinsem.pdf) for LLVM semantics where `getelementptr inbounds` with offset 0 isn't quite the identity function but never returns `poison` (it affects the provenance of the pointer but in a way that doesn't matter if this pointer is never used for memory accesses), and indeed this is likely necessary to consistently describe LLVM semantics. But with the informal LLVM LangRef that we have right now, and with LLVM devs insisting otherwise, it seems unwise to rely on this.
Rename/Deprecate LayoutErr in favor of LayoutError
Implements rust-lang/wg-allocators#73.
This patch renames LayoutErr to LayoutError, and uses a type alias to support users using the old name.
The new name will be instantly stable in release 1.49 (current nightly), the type alias will become deprecated in release 1.51 (so that when the current nightly is 1.51, 1.49 will be stable).
This is the only error type in `std` that ends in `Err` rather than `Error`, if this PR lands all stdlib error types will end in `Error` 🥰
BTreeMap: fix pointer provenance rules in underfullness
Continuing on #78480, and for readability, and possibly for performance: avoid aliasing when handling underfull nodes, and consolidate the code doing that. In particular:
- Avoid the rather explicit aliasing for internal nodes in `remove_kv_tracking`.
- Climb down to the root to handle underfull nodes using a reborrowed handle, rather than one copied with `ptr::read`, before resuming on the leaf level.
- Integrate the code tracking leaf edge position into the functions performing changes, rather than bolting it on.
r? `@Mark-Simulacrum`
Implement BTreeMap::retain and BTreeSet::retain
Adds new methods `BTreeMap::retain` and `BTreeSet::retain`. These are implemented on top of `drain_filter` (#70530).
The API of these methods is identical to `HashMap::retain` and `HashSet::retain`, which were implemented in #39560 and stabilized in #36648. The docs and tests are also copied from HashMap/HashSet.
The new methods are unstable, behind the `btree_retain` feature gate, with tracking issue #79025. See also rust-lang/rfcs#1338.
commit c547d5fabcd756515afa7263ee5304965bb4c497
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 11:22:23 2020 +0000
test: updating ui/hygiene/panic-location.rs expected
commit 2af03769c4ffdbbbad75197a1ad0df8c599186be
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 10:43:30 2020 +0000
fix: documentation unresolved link
commit c4b0df361ce27d7392d8016229f2e0265af32086
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 02:58:31 2020 +0000
style: compiling with Rust's style guidelines
commit bdd2de5f3c09b49a18e3293f2457fcab25557c96
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 02:56:31 2020 +0000
refactor: removing ignore-tidy-filelength
commit fcc4b3bc41f57244c65ebb8e4efe4cbc9460b5a9
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 02:51:35 2020 +0000
refactor: moving trait RingSlices to ring_slices.rs
commit 2f0cc539c06d8841baf7f675168f68ca7c21e68e
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 02:46:09 2020 +0000
refactor: moving struct PairSlices to pair_slices.rs
commit a55d3ef1dab4c3d85962b3a601ff8d1f7497faf2
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 02:31:45 2020 +0000
refactor: moving struct Iter to iter.rs
commit 76ab33a12442a03726f36f606b4e0fe70f8f246b
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 02:24:32 2020 +0000
refactor: moving struct IntoIter into into_iter.rs
commit abe0d9eea2933881858c3b1bc09df67cedc5ada5
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 02:19:07 2020 +0000
refactor: moving struct IterMut into iter_mut.rs
commit 70ebd6420335e1895e2afa2763a0148897963e24
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 01:49:15 2020 +0000
refactor: moved macros into macros.rs
commit b08dd2add994b04ae851aa065800bd8bd6326134
Author: C <DeveloperC@protonmail.com>
Date: Sat Oct 31 01:05:36 2020 +0000
refactor: moving vec_deque.rs to vec_deque/mod.rs
Improve BinaryHeap performance
By changing the condition in the loops from `child < end` to `child < end - 1` we're guaranteed that `right = child + 1 < end` and since finding the index of the biggest sibling can be done with an arithmetic operation we can remove a branch from the loop body. The case where there's no right child, i.e. `child == end - 1` is instead handled outside the loop, after it ends; note that if the loops ends early we can use `return` instead of `break` since the check `child == end - 1` will surely fail.
I've also removed a call to `<[T]>::swap` that was hiding a bound check that [wasn't being optimized by LLVM](https://godbolt.org/z/zrhdGM).
A quick benchmarks on my pc shows that the gains are pretty significant:
|name |before ns/iter |after ns/iter |diff ns/iter |diff % |speedup |
|---------------------|----------------|---------------|--------------|----------|--------|
|find_smallest_1000 | 352,565 | 260,098 | -92,467 | -26.23% | x 1.36 |
|from_vec | 676,795 | 473,934 | -202,861 | -29.97% | x 1.43 |
|into_sorted_vec | 469,511 | 304,275 | -165,236 | -35.19% | x 1.54 |
|pop | 483,198 | 373,778 | -109,420 | -22.64% | x 1.29 |
The other 2 benchmarks for `BinaryHeap` (`peek_mut_deref_mut` and `push`) weren't impacted and as such didn't show any significant change.
BTreeMap: split off most code of append
To complete #78056, move the last single-purpose pieces of code out of map.rs into a separate module. Also, tweaked documentation and safeness - I doubt think this code would be safe if the iterators passed in wouldn't be as sorted as the method says they should be - and bounds on MergeIterInner.
r? ```@Mark-Simulacrum```
Workaround for "could not fully normalize" ICE
Workaround for "could not fully normalize" ICE (#78139) by removing the `needs_drop::<T>()` calls triggering it.
Corresponding beta PR: #78845Fixes#78139 -- the underlying bug is likely not fixed but we don't have another test case isolated for now, so closing.
fix some incorrect aliasing in the BTree
This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)
Cc ````````@ssomers````````
BTreeMap: stop mistaking node for an orderly place
A second mistake in #77612 was to ignore the node module's rightful comment "this module doesn't care whether the entries are sorted". And there's a much simpler way to visit the keys in order, if you check this separately from a single pass checking everything.
r? ````````@Mark-Simulacrum````````
Partially fix#55002, deprecate in another release
Co-authored-by: Ashley Mannix <kodraus@hey.com>
Update stable version for stabilize_spin_loop
Co-authored-by: Joshua Nelson <joshua@yottadb.com>
Use better example for spinlock
As suggested by KodrAus
Remove renamed_spin_loop already available in master
Fix spin loop example
Move Vec UI tests to unit tests when possible
Helps with #76268.
I'm moving the tests using `Vec` or `VecDeque`.
````@rustbot```` modify labels: A-testsuite C-cleanup T-libs
fix various aliasing issues in the standard library
This fixes various cases where the standard library either used raw pointers after they were already invalidated by using the original reference again, or created raw pointers for one element of a slice and used it to access neighboring elements.
Fix doc links to std::fmt
`std::format` and `core::write` macros' docs linked to `core::fmt` for format string reference, even though only `std::fmt` has format string documentation (and the link titles were `std::fmt`)
std::format and core::write macros' docs linked to core::fmt for format string reference, even though only std::fmt has format string documentation and the link titles were std::fmt.
Prevent String::retain from creating non-utf8 strings when abusing panic
Fixes#78498
The idea is the same as `Vec::drain`, set the len to 0 so that nobody can observe the broken invariant if it escapes the function (in this case if `f` panics)
BTreeMap: move generic support functions out of navigate.rs
A preparatory step chipped off #78104, useful in general (if at all).
r? `@Mark-Simulacrum`
BTreeMap: stop mistaking node::MIN_LEN for a node level constraint
Correcting #77612 that fell into the trap of assuming that node::MIN_LEN is an imposed minimum everywhere, and trying to make it much more clear it is an offered minimum at the node level.
r? @Mark-Simulacrum
replace `#[allow_internal_unstable]` with `#[rustc_allow_const_fn_unstable]` for `const fn`s
`#[allow_internal_unstable]` is currently used to side-step feature gate and stability checks.
While it was originally only meant to be used only on macros, its use was expanded to `const fn`s.
This pr adds stricter checks for the usage of `#[allow_internal_unstable]` (only on macros) and introduces the `#[rustc_allow_const_fn_unstable]` attribute for usage on `const fn`s.
This pr does not change any of the functionality associated with the use of `#[allow_internal_unstable]` on macros or the usage of `#[rustc_allow_const_fn_unstable]` (instead of `#[allow_internal_unstable]`) on `const fn`s (see https://github.com/rust-lang/rust/issues/69399#issuecomment-712911540).
Note: The check for `#[rustc_allow_const_fn_unstable]` currently only validates that the attribute is used on a function, because I don't know how I would check if the function is a `const fn` at the place of the check. I therefore openend this as a 'draft pull request'.
Closesrust-lang/rust#69399
r? @oli-obk
revise Hermit's mutex interface to support the behaviour of StaticMutex
rust-lang/rust#77147 simplifies things by splitting this Mutex type into two types matching the two use cases: StaticMutex and MovableMutex. To support the new behavior of StaticMutex, we move part of the mutex implementation into libstd.
The interface to the OS changed. Consequently, I removed a few functions, which aren't longer needed.
Check for exhaustion in RangeInclusive::contains and slicing
When a range has finished iteration, `is_empty` returns true, so it
should also be the case that `contains` returns false.
Fixes#77941.
Doc formating consistency between slice sort and sort_unstable, and big O notation consistency
Updated documentation for slice sorting methods to be consistent between stable and unstable versions, which just ended up being minor formatting differences.
I also went through and updated any doc comments with big O notation to be consistent with #74010 by italicizing them rather than having them in a code block.
Move `slice::check_range` to `RangeBounds`
Since this method doesn't take a slice anymore (#76662), it makes more sense to define it on `RangeBounds`.
Questions:
- Should the new method be `assert_len` or `assert_length`?
BTreeMap: refactor Entry out of map.rs into its own file
btree/map.rs is approaching the 3000 line mark, splitting out the entry
code buys about 500 lines of headroom.
I've created this PR because the changes I've made in #77438 will push `map.rs` over the 3000 line limit and cause tidy to complain.
I picked `Entry` to factor out because it feels less tightly coupled to the rest of `BTreeMap` than the various iterator implementations.
Related: #60302
BTreeMap: improve gdb introspection of BTreeMap with ZST keys or values
I accidentally pushed an earlier revision in #77788: it changes the index of tuples for BTreeSet from ""[{}]".format(i) to "key{}".format(i). Which doesn't seem to make the slightest difference on my linux box nor on CI. In fact, gdb doesn't make any distinction between "key{}" and "val{}" for a BTreeMap either, leading to confusing output if you test more. But easy to improve.
r? @Mark-Simulacrum
liballoc: VecDeque: Add binary search functions
I am submitting rust-lang/rfcs#2997 as a PR as suggested by @scottmcm
I haven't yet created a tracking issue - if there's a favorable feedback I'll create one and update the issue links in the unstable attribs.
Remove shrink_to_fit from default ToString::to_string implementation.
As suggested by `@scottmcm` on Zulip. shrink_to_fit() seems like the wrong thing to do here in most use cases of to_string(). Would be intereseting to see if it makes any difference in a timer run.
r? `@joshtriplett`
fix __rust_alloc_error_handler comment
`__rust_alloc_error_handler` was added in the same `extern` block as the allocator functions, but the comment there was not actually correct for `__rust_alloc_error_handler`. So move it down to the rest of the default allocator handling with a fixed comment. At least the comment reflects my understanding of what happens, please check carefully. :)
r? @Amanieu Cc @haraldh
BTreeMap: comment why drain_filter's size_hint is somewhat pessimistic
The `size_hint` of the `DrainFilter` iterator doesn't adjust as you iterate. This hardly seems important to me, but there has been a comparable PR #64383 in the past. I guess a scenario is that you first iterate half the map manually and keep most of the key/value pairs in the map, and then tell the predicate to drain most of the key/value pairs and `.collect` the iterator over the remaining half of the map.
I am totally ambivalent whether this is better or not.
r? @Mark-Simulacrum
Add PartialEq impls for Vec <-> slice
This is a follow-up to #71660 and rust-lang/rfcs#2917 to add two more missing vec/slice PartialEq impls:
```
impl<A, B> PartialEq<[B]> for Vec<A> where A: PartialEq<B> { .. }
impl<A, B> PartialEq<Vec<B>> for [A] where A: PartialEq<B> { .. }
```
Since this is insta-stable, it should go through the `@rust-lang/libs` FCP process. Note that I used version 1.47.0 for the `stable` attribute because I assume this will not merge before the 1.46.0 branch is cut next week.
Remove `Box::leak_with_alloc`
Add leak-test for box with allocator
Rename `AllocErr` to `AllocError` in leak-test
Add `Box::alloc` and adjust examples to use the new API
Replace some once(x).chain(once(y)) with [x, y] IntoIter
Now that we have by-value array iterators that are [already used](25c8c53dd9/compiler/rustc_hir/src/def.rs (L305-L307))...
For example,
```diff
- once(self.type_ns).chain(once(self.value_ns)).chain(once(self.macro_ns)).filter_map(|it| it)
+ IntoIter::new([self.type_ns, self.value_ns, self.macro_ns]).filter_map(|it| it)
```
BTreeMap: admit the existence of leaf edges in comments
The btree code is ambiguous about leaf edges (i.e., edges within leaf nodes). Iteration relies on them heavily, but some of the comments suggest there are no leaf edges (extracted from #77025)
r? @Mark-Simulacrum
BTreeMap: complete the compile-time test_variance test case
Some of the items added to the new `test_sync` belonged in the old `test_variance` as well. And fixed inconsistent paths to nearby modules.
r? @Mark-Simulacrum
Implement Make `handle_alloc_error` default to panic (for no_std + liballoc)
Related: https://github.com/rust-lang/rust/issues/66741
Guarded with `#![feature(default_alloc_error_handler)]` a default
`alloc_error_handler` is called, if a custom allocator is used and no
other custom `#[alloc_error_handler]` is defined.
Allow Weak::as_ptr and friends for unsized T
Relaxes `impl<T> Weak<T>` to `impl<T: ?Sized> Weak<T>` for the methods `rc::Weak::as_ptr`, `into_raw`, and `from_raw`.
Follow-up to #73845, which did most of the impl work to make these functions work for `T: ?Sized`.
We still have to adjust the implementation of `Weak::from_raw` here, however, because I missed a use of `ptr.is_null()` previously. This check was necessary when `into`/`from_raw` were first implemented, as `into_raw` returned `ptr::null()` for dangling weak. However, we now just (wrapping) offset dangling weaks' pointers the same as nondangling weak, so the null check is no longer necessary (or even hit). (I can submit just 17a928f as a separate PR if desired.)
As a nice side effect, moves the `fn is_dangling` definition closer to `Weak::new`, which creates the dangling weak.
This technically stabilizes that "something like `align_of_val_raw`" is possible to do. However, I believe the part of the functionality required by these methods here -- specifically, getting the alignment of a pointee from a pointer where it may be dangling iff the pointee is `Sized` -- is uncontroversial enough to stabilize these methods without a way to implement them on stable Rust.
r? `@RalfJung,` who reviewed #73845.
ATTN: This changes (relaxes) the (input) generic bounds on stable fn!
Fix Debug implementations of some of the HashMap and BTreeMap iterator types
HashMap's `ValuesMut`, BTreeMaps `ValuesMut`, IntoValues and `IntoKeys` structs were printing both keys and values on their Debug implementations. But they are iterators over either keys or values. Irrelevant values should not be visible. With this PR, they only show relevant fields.
This fixes#75297.
[Here's an example code.](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=0c79356ed860e347a0c1a205616f93b7) This prints this on nightly:
```
ValuesMut { inner: IterMut { range: [(1, "hello"), (2, "goodbye")], length: 2 } }
IntoKeys { inner: [(1, "hello"), (2, "goodbye")] }
IntoValues { inner: [(1, "hello"), (2, "goodbye")] }
[(2, "goodbye"), (1, "hello")]
```
After the patch this example prints these instead:
```
["hello", "goodbye"]
["hello", "goodbye"]
[1, 2]
["hello", "goodbye"]
```
I didn't add test cases for them, since I couldn't see any tests for Debug implementations anywhere. But please let me know if I should add it to a specific place.
r? @dtolnay
Related: https://github.com/rust-lang/rust/issues/66741
Guarded with `#![feature(default_alloc_error_handler)]` a default
`alloc_error_handler` is called, if a custom allocator is used and no
other custom `#[alloc_error_handler]` is defined.
The panic message does not contain the size anymore, because it would
pull in the fmt machinery, which would blow up the code size
significantly.
Resolve `crate` in intra-doc links properly across crates
Closes https://github.com/rust-lang/rust/issues/77193; see https://github.com/rust-lang/rust/issues/77193#issuecomment-699065946 for an explanation of what's going on here.
~~This also fixes the BTreeMap docs that have been broken for a while; see the description on the second commit for why and how.~~ Nope, see the second commit for why the link had to be changed.
r? `@Manishearth`
cc `@dylni`
`@dylni` note that this doesn't solve your original problem - now _both_ `with_code` and `crate::with_code` will be broken links. However this will fix a lot of other broken links (in particular I think https://docs.rs/sqlx/0.4.0-beta.1/sqlx/query/struct.Query.html is because of this bug). I'll open another issue for resolving additional docs in the new scope.
UI to unit test for those using Cell/RefCell/UnsafeCell
Helps with #76268.
I'm working on all files using `Cell` and moving them to unit tests when possible.
r? @matklad
Previously, `BTreeMap` tried to link to `crate::collections`, intending
for the link to go to `std/collections/index.html`. But `BTreeMap` is
defined in `alloc`, so after the fix in the previous commit, the links
instead went to `alloc/collections/index.html`, which has almost no
information.
This changes it to link to `index.html`, which only works when viewing
from `std::collections::BTreeMap`, the most common place to visit the
docs. Fixing it to work from anywhere would require the docs for
`std::collections` to be duplicated in `alloc::collections`, which in
turn would require HashMap to be `alloc` for intra-doc links to work
(https://github.com/rust-lang/rust/issues/74481).
Rust vec bench import specific rand::RngCore
Using `RngCore` import for side effects is clearer than `*` which may bring it unnecessary more stuff than needed, it is also more explicit doing so.
@pickfire change `LEN = 16384` (and pos) and `once` instead of `[0].iter()` after this.
@rustbot modify labels: +C-cleanup +A-testsuite
It's possible for method resolution to pick this method over a lower
priority stable method, causing compilation errors. Since this method
is permanently unstable, give it a name that is very unlikely to be used
in user code.
BtreeMap: refactoring around edges
Parts chipped off a more daring effort, that the btree benchmarks judge to be performance-neutral.
r? @Mark-Simulacrum
Use `Self` in docs when possible
Fixes#76542.
I used `rg '\s*//[!/]\s+fn [\w_]+\(&?self, ' .` in `library/` to find instances, I found some with that and some by manually checking.
@rustbot modify labels: C-enhancement T-doc
Avoid useless sift_down when std::collections::binary_heap::PeekMut is never mutably dereferenced
If `deref_mut` is never called then it's not possible for the element to be mutated without internal mutability, meaning there's no need to call `sift_down`.
This could be a little improvement in cases where you want to mutate the biggest element of the heap only if it satisfies a certain predicate that needs only read access to the element.
Move to intra-doc links in collections/vec_deque.rs and collections/vec_deque/drain.rs
Helps with #75080.
@rustbot modify labels: T-doc, A-intra-doc-links
Remove unused feature gates from library/ crates
Removes some unused feature gates from library crates. It's likely not a complete list as I only tested a subset for which it's more likely that it is unused.
Test and fix Send and Sync traits of BTreeMap artefacts
Fixes#76686.
I'm not quite sure what all this implies. E.g. comparing with the definitions for `NodeRef` in node.rs, maybe an extra bound `T: 'a` is useful for something. The test compiles on stable/beta (apart from `drain_filter`) so I bet `Sync` is equally desirable.
r? @Mark-Simulacrum
BTreeMap: wrap node's raw parent pointer in NonNull
Now that the other `*const` (root) is gone, seemed like a small step forward.
r? `@Mark-Simulacrum`
Add as_str() to string::Drain.
Vec's Drain recently [had its `.as_slice()` stabilized](https://github.com/rust-lang/rust/pull/72584), but String's Drain was still missing the analogous `.as_str()`. This adds that.
Also improves the Debug implementation, which now shows the remaining data instead of just `"Drain { .. }"`.
Add associated constant `BITS` to all integer types
Recently I've regularly come across this snippet (in a few different crates, including `core` and `std`):
```rust
std::mem::size_of<usize>() * 8
```
I think it's time for a `usize::BITS`.
BTreeMap: avoid slices even more
Epilogue to #73971: it seems the compiler is unable to realize that creating a slice and `get_unchecked`-ing one element is a simple fetch. So try to spell it out for the only remaining but often invoked case.
Also, the previous code doesn't seem fair game to me, using `get_unchecked` to reach beyond the end of a slice. Although the local function `slice_insert` also does that.
r? `@Mark-Simulacrum`
Add array_windows fn
This mimicks the functionality added by array_chunks, and implements a const-generic form of
`windows`. It makes egregious use of `unsafe`, but by necessity because the array must be
re-interpreted as a slice of arrays, and unlike array_chunks this cannot be done by casting the
original array once, since each time the index is advanced it needs to move one element, not
`N`.
I'm planning on adding more tests, but this should be good enough as a premise for the functionality.
Notably: should there be more functions overwritten for the iterator implementation/in general?
~~I've marked the issue as #74985 as there is no corresponding exact issue for `array_windows`, but it's based of off `array_chunks`.~~
Edit: See Issue #75027 created by @lcnr for tracking issue
~~Do not merge until I add more tests, please.~~
r? @lcnr
Updated issue to #75027
Update to rm oob access
And hopefully fix docs as well
Fixed naming conflict in test
Fix test which used 1-indexing
Nth starts from 0, woops
Fix a bunch of off by 1 errors
See https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=757b311987e3fae1ca47122969acda5a
Add even more off by 1 errors
And also write `next` and `next_back` in terms of `nth` and `nth_back`.
Run fmt
Fix forgetting to change fn name in test
add nth_back test & document unsafe
Remove as_ref().unwrap()
Documented occurrences of unsafe, noting what invariants are maintained
Fix liballoc test suite for Miri
Mostly, fix the regression introduced by https://github.com/rust-lang/rust/pull/75207 that caused slices (i.e., references) to be created to invalid memory or memory that has aliasing pointers that we want to keep valid. @dylni this changes the type of `check_range` to only require the length, not the full reference to the slice, which indeed is all the information this function requires.
Also reduce the size of a test introduced in https://github.com/rust-lang/rust/pull/70793 to make it not take 3 minutes in Miri.
This makes https://github.com/RalfJung/miri-test-libstd work again.
Detect overflow in proc_macro_server subspan
* Detect overflow in proc_macro_server subspan
* Add tests for overflow in Vec::drain
* Add tests for overflow in String / VecDeque operations using ranges
Optimize behavior of vec.split_off(0) (take all)
Optimization improvement to `split_off()` so the performance meets the
intuitively expected behavior when `at == 0`, avoiding the current behavior
of copying the entire vector.
The change honors documented behavior that the original vector's
"previous capacity unchanged".
This improvement better supports the pattern for building and flushing a
buffer of elements, such as the following:
```rust
let mut vec = Vec::new();
loop {
vec.push(something);
if condition_is_met {
process(vec.split_off(0));
}
}
```
`Option` wrapping is the first alternative I thought of, but is much
less obvious and more verbose:
```rust
let mut capacity = 1;
let mut vec: Option<Vec<Stuff>> = None;
loop {
vec.get_or_insert_with(|| Vec::with_capacity(capacity)).push(something);
if condition_is_met {
capacity = vec.capacity();
process(vec.take().unwrap());
}
}
```
Directly using `mem::replace()` (instead of calling`split_off()`) could work,
but `mem::replace()` is a more advanced tool for Rust developers, and in
this case, I believe developers would assume the standard library should
be sufficient for the purpose described here.
The benefit of the approach to this change is it does not change the
existing API contract, but improves the peformance of `split_off(0)` for
`Vec`, `String` (which delegates `split_off()` to `Vec`), and any other
existing use cases.
This change adds tests to validate the behavior of `split_off()` with
regard to capacity, as originally documented, and confirm that behavior
still holds, when `at == 0`.
The change is an implementation detail, and does not require a
documentation change, but documenting the new behavior as part of its
API contract may benefit future users.
(Let me know if I should make that documentation update.)
Note, for future consideration:
I think it would be helpful to introduce an additional method to `Vec`
(if not also to `String`):
```
pub fn take_all(&mut self) -> Self {
self.split_off(0)
}
```
This would make it more clear how `Vec` supports the pattern, and make
it easier to find, since the behavior is similar to other `take()`
methods in the Rust standard library.
r? `@wesleywiser`
FYI: `@tmandry`
Optimization improvement to `split_off()` so the performance meets the
intuitively expected behavior when `at == 0`, avoiding the current
behavior of copying the entire vector.
The change honors documented behavior that the method leaves the
original vector's "previous capacity unchanged".
This improvement better supports the pattern for building and flushing a
buffer of elements, such as the following:
```rust
let mut vec = Vec::new();
loop {
vec.push(something);
if condition_is_met {
process(vec.split_off(0));
}
}
```
`Option` wrapping is the first alternative I thought of, but is much
less obvious and more verbose:
```rust
let mut capacity = 1;
let mut vec: Option<Vec<Stuff>> = None;
loop {
vec.get_or_insert_with(|| Vec::with_capacity(capacity)).push(something);
if condition_is_met {
capacity = vec.capacity();
process(vec.take().unwrap());
}
}
```
Directly applying `mem::replace()` could work, but `mem::` functions are
typically a last resort, when a developer is actively seeking better
performance than the standard library provides, for example.
The benefit of the approach to this change is it does not change the
existing API contract, but improves the peformance of `split_off(0)` for
`Vec`, `String` (which delegates `split_off()` to `Vec`), and any other
existing use cases.
This change adds tests to validate the behavior of `split_off()` with
regard to capacity, as originally documented, and confirm that behavior
still holds, when `at == 0`.
The change is an implementation detail, and does not require a
documentation change, but documenting the new behavior as part of its
API contract may benefit future users.
(Let me know if I should make that documentation update.)
Note, for future consideration:
I think it would be helpful to introduce an additional method to `Vec`
(if not also to `String`):
```
pub fn take_all(&mut self) -> Self {
self.split_off(0)
}
```
This would make it more clear how `Vec` supports the pattern, and make
it easier to find, since the behavior is similar to other `take()`
methods in the Rust standard library.
Remove internal and unstable MaybeUninit::UNINIT.
Looks like it is no longer necessary, as `uninit_array()` can be used instead in the few cases where it was needed.
(I wanted to just add `#[doc(hidden)]` to remove clutter from the documentation, but looks like it can just be removed entirely.)
Warn for #[unstable] on trait impls when it has no effect.
Earlier today I sent a PR with an `#[unstable]` attribute on a trait `impl`, but was informed that this attribute has no effect there. (comment: https://github.com/rust-lang/rust/pull/76525#issuecomment-689678895, issue: https://github.com/rust-lang/rust/issues/55436)
This PR adds a warning for this situation. Trait `impl` blocks with `#[unstable]` where both the type and the trait are stable will result in a warning:
```
warning: An `#[unstable]` annotation here has no effect. See issue #55436 <https://github.com/rust-lang/rust/issues/55436> for more information.
--> library/std/src/panic.rs:235:1
|
235 | #[unstable(feature = "integer_atomics", issue = "32976")]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
---
It detects three problems in the existing code:
1. A few `RefUnwindSafe` implementations for the atomic integer types in `library/std/src/panic.rs`. Example:
d92155bf6a/library/std/src/panic.rs (L235-L236)
2. An implementation of `Error` for `LayoutErr` in `library/std/srd/error.rs`:
d92155bf6a/library/std/src/error.rs (L392-L397)
3. `From` implementations for `Waker` and `RawWaker` in `library/alloc/src/task.rs`. Example:
d92155bf6a/library/alloc/src/task.rs (L36-L37)
Case 3 interesting: It has a bound with an `#[unstable]` trait (`W: Wake`), so appears to have much effect on stable code. It does however break similar blanket implementations. It would also have immediate effect if `Wake` was implemented for any stable type. (Which is not the case right now, but there are no warnings in place to prevent it.) Whether this case is a problem or not is not clear to me. If it isn't, adding a simple `c.visit_generics(..);` to this PR will stop the warning for this case.
Eliminate mut reference UB in Drop impl for Rc<T>
This changes `self.ptr.as_mut()` with `get_mut_unchecked` which
does not use an intermediate reference. Arc<T> already handled this
case properly.
Fixes#76509
Add `slice::array_chunks_mut`
This follows `array_chunks` from #74373 with a mutable version, `array_chunks_mut`. The implementation is identical apart from mutability. The new tests are adaptations of the `chunks_exact_mut` tests, plus an inference test like the one for `array_chunks`.
I reused the unstable feature `array_chunks` and tracking issue #74985, but I can separate that if desired.
r? `@withoutboats`
cc `@lcnr`
BTreeMap: move up reference to map's root from NodeRef
Since the introduction of `NodeRef` years ago, it also contained a mutable reference to the owner of the root node of the tree (somewhat disguised as *const). Its intent is to be used only when the rest of the `NodeRef` is no longer needed. Moving this to where it's actually used, thought me 2 things:
- Some sort of "postponed mutable reference" is required in most places that it is/was used, and that's exactly where we also need to store a reference to the length (number of elements) of the tree, for the same reason. The length reference can be a normal reference, because the tree code does not care about tree length (just length per node).
- It's downright obfuscation in `from_sorted_iter` (transplanted to #75329)
- It's one of the reasons for the scary notice on `reborrow_mut`, the other one being addressed in #73971.
This does repeat the raw pointer code in a few places, but it could be bundled up with the length reference.
r? `@Mark-Simulacrum`
This avoids overlapping a reference covering the data field,
which may be changed due in concurrent conditions. This fully
fixed the UB mainfested with `new_cyclic`.
Since trait implementations cannot be unstable, we should only add them
when the as_str feature gets stabilized. Until then, only `.as_str()` is
available (behind a feature gate).
Move various ui const tests to `library`
Move:
- `src\test\ui\consts\const-nonzero.rs` to `library\core`
- `src\test\ui\consts\ascii.rs` to `library\core`
- `src\test\ui\consts\cow-is-borrowed` to `library\alloc`
Part of #76268
r? @matklad
Move some Vec UI tests into alloc unit tests
A bit of work towards #76268, makes a number of the Vec UI tests that are simply running code into unit tests. Ensured that they are being run when testing liballoc locally.
rename MaybeUninit slice methods
The `first` methods conceptually point to the whole slice, not just its first element, so rename them to be consistent with the raw ptr methods on ref-slices.
Also, do the equivalent of https://github.com/rust-lang/rust/pull/76047 for the slice reference getters, and make them part of https://github.com/rust-lang/rust/issues/63569 (so far they somehow had no tracking issue).
* first_ptr -> slice_as_ptr
* first_ptr_mut -> slice_as_mut_ptr
* slice_get_ref -> slice_assume_init_ref
* slice_get_mut -> slice_assume_init_mut
BTreeMap: introduce marker::ValMut and reserve Mut for unique access
The mutable BTreeMap iterators (apart from `DrainFilter`) are double-ended, meaning they have to rely on a front and a back handle that each represent a reference into the tree. Reserve a type category `marker::ValMut` for them, so that we guarantee that they cannot reach operations on handles with borrow type `marker::Mut`and that these operations can assume unique access to the tree.
Including #75195, benchmarks report no genuine change:
```
benchcmp old new --threshold 5
name old ns/iter new ns/iter diff ns/iter diff % speedup
btree::map::iter_100 3,333 3,023 -310 -9.30% x 1.10
btree::map::range_unbounded_vs_iter 36,624 31,569 -5,055 -13.80% x 1.16
```
r? @Mark-Simulacrum
This is very similar to the existing `Box<[T; N]>: TryFrom<Box<[T]>>`, but allows avoiding the `shrink_to_fit` if you have a vector and not a boxed slice.
Move:
- `src\test\ui\consts\const-nonzero.rs` to `library\core`
- `src\test\ui\consts\ascii.rs` to `library\core`
- `src\test\ui\consts\cow-is-borrowed` to `library\alloc`
Part of #76268
The InPlaceIterable debug assert checks that the write pointer
did not advance beyond the read pointer. But TrustedRandomAccess
never advances the read pointer, thus triggering the assert.
Skip the assert if the source pointer did not change during iteration.
The optimization meant that every extend code path had to emit llvm
IR for from_iter and extend spec_extend, which likely impacts
compile times while only improving a few edge-cases
