Update the minimum external LLVM to 18
With this change, we'll have stable support for LLVM 18 and 19.
For reference, the previous increase to LLVM 17 was #122649.
cc `@rust-lang/wg-llvm`
r? nikic
Win: Open dir for sync access in remove_dir_all
A small follow up to #129800.
We should explicitly open directories for synchronous access. We ultimately use `GetFileInformationByHandleEx` to read directories which should paper over any issues caused by using async directory reads (or else return an error) but it's better to do the right thing in the first place. Note though that `delete` does not read or write any data so it's not necessary there.
Pass `fmt::Arguments` by reference to `PanicInfo` and `PanicMessage`
Resolves#129330
For some reason after #115974 and #126732 optimizations applied to panic handler became worse and compiler stopped removing panic locations if they are not used in the panic message. This PR fixes that and maybe we can merge it into beta before rust 1.81 is released.
Note: optimization only works with `lto = "fat"`.
r? libs-api
Take more advantage of the `isize::MAX` limit in `Layout`
Things like `padding_needed_for` are current implemented being super careful to handle things like `Layout::size` potentially being `usize::MAX`.
But now that #95295 has happened, that's no longer a concern. It's possible to add two `Layout::size`s together without risking overflow now.
So take advantage of that to remove a bunch of checked math that's not actually needed. For example, the round-up-and-add-next-size in `extend` doesn't need any overflow checks at all, just the final check for compatibility with the alignment.
(And while I was doing that I made it all unstably const, because there's nothing in `Layout` that's fundamentally runtime-only.)
Things like `padding_needed_for` are current implemented being super careful to handle things like `Layout::size` potentially being `usize::MAX`.
But now that 95295 has happened, that's no longer a concern. It's possible to add two `Layout::size`s together without risking overflow now.
So take advantage of that to remove a bunch of checked math that's not actually needed. For example, the round-up-and-add-next-size in `extend` doesn't need any overflow checks at all, just the final check for compatibility with the alignment.
(And while I was doing that I made it all unstably const, because there's nothing in `Layout` that's fundamentally runtime-only.)
Remove uneeded PartialOrd bound in cmp::Ord::clamp
There is a `Self: PartialOrd` bound in `Ord::clamp`, but it is already required by the trait itself. Likely a left-over from the const trait deletion in 76dbe29104.
Reported-by: `@noeensarguet`
There is a Self: PartialOrd bound in Ord::clamp, but it is already
required by the trait itself. Likely a left-over from the const trait
deletion in 76dbe29104.
Reported-by: @noeensarguet
Add new_cyclic_in for Rc and Arc
Currently, new_cyclic_in does not exist for Rc and Arc. This is an oversight according to https://github.com/rust-lang/wg-allocators/issues/132.
This PR adds new_cyclic_in for Rc and Arc. The implementation is almost the exact same as new_cyclic with some small differences to make it allocator-specific. new_cyclic's implementation has been replaced with a call to `new_cyclic_in(data_fn, Global)`.
Remaining questions:
* ~~Is requiring Allocator to be Clone OK? According to https://github.com/rust-lang/wg-allocators/issues/88, Allocators should be cheap to clone. I'm just hesitant to add unnecessary constraints, though I don't see an obvious workaround for this function since many called functions in new_cyclic_in expect an owned Allocator. I see Allocator.by_ref() as an option, but that doesn't work on when creating Weak { ptr: init_ptr, alloc: alloc.clone() }, because the type of Weak then becomes Weak<T, &A> which is incompatible.~~ Fixed, thank you `@zakarumych!` This PR no longer requires the allocator to be Clone.
* Currently, new_cyclic_in's documentation is almost entirely copy-pasted from new_cyclic, with minor tweaks to make it more accurate (e.g. Rc<T> -> Rc<T, A>). The example section is removed to mitigate redundancy and instead redirects to cyclic_in. Is this appropriate?
* ~~The comments in new_cyclic_in (and much of the implementation) are also copy-pasted from new_cyclic. Would it be better to make a helper method new_cyclic_in_internal that both functions call, with either Global or the custom allocator? I'm not sure if that's even possible, since the internal method would have to return Arc<T, Global> and I don't know if it's possible to "downcast" that to an Arc<T>. Maybe transmute would work here?~~ Done, thanks `@zakarumych`
* Arc::new_cyclic is #[inline], but Rc::new_cyclic is not. Which is preferred?
* nit: does it matter where in the impl block new_cyclic_in is defined?
In the implementation of `force_mut`, I chose performance over safety.
For `LazyLock` this isn't really a choice; the code has to be unsafe.
But for `LazyCell`, we can have a full-safe implementation, but it will
be a bit less performant, so I went with the unsafe approach.
fix: Remove duplicate `LazyLock` example.
The top-level docs for `LazyLock` included two lines of code, each with an accompanying comment, that were identical and with nearly- identical comments. This looks like an oversight from a past edit which was perhaps trying to rewrite an existing example but ended up duplicating rather than replacing, though I haven't gone back through the Git history to check.
This commit removes what I personally think is the less-clear of the two examples.
[library/std/src/process.rs] `PartialEq` for `ExitCode`
Converting a third-party CLI to a library so started passing around [`std::process::ExitCode`](https://doc.rust-lang.org/std/process/struct.ExitCode.html) in an `Either`. Then I realised the tests can't be modified to compare equality of `ExitCode`s.
This PR fixes this oversight.
The top-level docs for `LazyLock` included two lines of code, each
with an accompanying comment, that were identical and with nearly-
identical comments. This looks like an oversight from a past edit
which was perhaps trying to rewrite an existing example but ended
up duplicating rather than replacing, though I haven't gone back
through the Git history to check.
This commit removes what I personally think is the less-clear of
the two examples.
Signed-off-by: Andrew Lilley Brinker <alilleybrinker@gmail.com>
Document futility of printing temporary pointers
In the user forum I've seen a few people trying to understand how borrowing and moves are implemented by peppering their code with printing of `{:p}` of references to variables and expressions. This is a bad idea. It gives misleading and confusing results, because of autoderef magic, printing pointers of temporaries on the stack, and/or causes LLVM to optimize code differently when values had their address exposed.
simplify float::classify logic
I played around with the float-classify test in the hope of triggering x87 bugs by strategically adding `black_box`, and still the exact expression `@beetrees` suggested [here](https://github.com/rust-lang/rust/pull/129835#issuecomment-2325661597) remains the only case I found where we get the wrong result on x87. Curiously, this bug only occurs when MIR optimizations are enabled -- probably the extra inlining that does is required for LLVM to hit the right "bad" case in the backend. But even for that case, it makes no difference whether `classify` is implemented in the simple bit-pattern-based version or the more complicated version we had before.
Without even a single testcase that can distinguish our `classify` from the naive version, I suggest we switch to the naive version.
Add `core::panic::abort_unwind`
`abort_unwind` is like `catch_unwind` except that it aborts the process if it unwinds, using the `#[rustc_nounwind]` mechanism also used by `extern "C" fn` to abort unwinding. The docs attempt to make it clear when to (rarely) and when not to (usually) use the function.
Although usage of the function is discouraged, having it available will help to normalize the experience when abort_unwind shims are hit, as opposed to the current ecosystem where there exist multiple common patterns for converting unwinding into a process abort.
For further information and justification, see the linked ACP.
- Tracking issue: https://github.com/rust-lang/rust/issues/130338
- ACP: https://github.com/rust-lang/libs-team/issues/441
