Use internal iteration in the Sum and Product impls of Result and Option
This PR adds internal iteration to the `ResultShunt` iterator type underlying the `Sum` and `Product` impls of `Result`. I had to change `ResultShunt` to hold a mutable reference to an error instead, similar to `itertools::ProcessResults`, in order to be able to pass the `ResultShunt` itself by value (which is necessary for internal iteration).
`ResultShunt::process` can unfortunately no longer be an associated function because that would make it generic over the lifetime of the error reference, which wouldn't work, so I turned it into the free function `process_results`.
I removed the `OptionShunt` type and forwarded the `Sum` and `Product` impls of `Option` to their respective impls of `Result` instead, to avoid having to repeat the internal iteration logic.
fix UB in a test
We used to compare two mutable references that were supposed to point to the same thing. That's no good.
Compare them as raw pointers instead.
Implement DoubleEndedIterator for iter::{StepBy, Peekable, Take}
Now that `DoubleEndedIterator::nth_back` has landed, `StepBy` and `Take` can have an efficient `DoubleEndedIterator` implementation. I don't know if there was any particular reason for `Peekable` not having a `DoubleEndedIterator` implementation, but it's quite trivial and I don't see any drawbacks to having it.
I'm not very happy about the implementation of `Peekable::try_rfold`, but I didn't see another way to only take the value out of `self.peeked` in case `self.iter.try_rfold` didn't exit early.
I only added `Peekable::rfold` (in addition to `try_rfold`) because its `Iterator` implementation has both `fold` and `try_fold` (and for similar reasons I added `Take::try_rfold` but not `Take::rfold`). Do we have any guidelines on whether we want both? If we do want both, maybe we should investigate which iterator adaptors override `try_fold` but not `fold` and add the missing implementations. At the moment I think that it's better to always have iterator adaptors implement both, because some iterators have a simpler `fold` implementation than their `try_fold` implementation.
The tests that I added may not be sufficient because they're all just existing tests where `next`/`nth`/`fold`/`try_fold` are replaced by their DEI counterparts, but I do think all paths are covered. Is there anything in particular that I should probably also test?
More questionmarks in doctests
This removes the other `unwrap`s in the macro doctests, replacing them with `?`. For now, we need to specify the main function including the return type, we can get rid of that once the return type suggestion for `fn main() { .. }` works correctly.
r? @QuietMisdreavus
`const fn`-ify `std::any::type_name` as laid out in #63084
A test, based on the one I added when I implemented support for the underlying `core::intrinsics::type_name` being allowed in `const fn` contexts, is included.
Remove mentions of removed `offset_to` method from `align_offset` docs
The `offset_to` method was deleted in https://github.com/rust-lang/rust/pull/52814.
The replacement for the removed method is `wrapping_offset_from`. However, neither method takes an `usize` as argument, so I don't think that it makes sense to mention them.
Rollup of 8 pull requests
Successful merges:
- #61856 (Lint attributes on function arguments)
- #62360 (Document that ManuallyDrop::drop should not called more than once)
- #62392 (Update minifier-rs version)
- #62871 (Explicit error message for async recursion.)
- #62995 (Avoid ICE when suggestion span is at Eof)
- #63053 (SystemTime docs: recommend Instant for elapsed time)
- #63081 (tidy: Cleanup the directory whitelist)
- #63088 (Remove anonymous_parameters from unrelated test)
Failed merges:
r? @ghost
Document that ManuallyDrop::drop should not called more than once
Double dropping is unsound (e.g. https://github.com/rust-lang/rust/issues/60977). This commit documents the fact that `ManuallyDrop::drop` should not be called multiple times on the same instance, as it might not be immediately obvious that this counts as a use of uninitialized data.
Refactoring use common code between option, result and accum
`Option` and `Result` have almost exactly the same code that in `accum.rs` that implement `Sum` and `Product`. This PR just move some code to use the same code for all of them. I believe is better to not implement this `Iterator` feature twice.
I'm not very familiar with pub visibility hope I didn't make then public. However, maybe these adapters could be useful and we could think to make then pub.
#59605#11084
r? @pnkfelix
squash of all commits for nth_back on ChunksMut
wip nth_back for chunks_mut
working chunksmut
fixed nth_back for chunksmut
Signed-off-by: wizAmit <amitforfriends_dns@yahoo.com>
r? @timvermeulen
r? @scottmcm
Optimize RefCell read borrowing
Instead of doing two comparisons we can do only one with a bit of cleverness.
LLVM currently can't do this optimization itself on x86-64.
