Fix Rc/Arc allocation layout
* Rounds allocation layout up to a multiple of alignment
* Adds a convenience method `Layout::pad_to_align` to perform rounding
Closes#55747
cc #55724
Implement rotate using funnel shift on LLVM >= 7
Implement the rotate_left and rotate_right operations using
llvm.fshl and llvm.fshr if they are available (LLVM >= 7).
Originally I wanted to expose the funnel_shift_left and
funnel_shift_right intrinsics and implement rotate_left and
rotate_right on top of them. However, emulation of funnel
shifts requires emitting a conditional to check for zero shift
amount, which is not necessary for rotates. I was uncomfortable
doing that here, as I don't want to rely on LLVM to optimize
away that conditional (and for variable rotates, I'm not sure it
can). We should revisit that question when we raise our minimum
version requirement to LLVM 7 and don't need emulation code
anymore.
Fixes#52457.
Implement the rotate_left and rotate_right operations using
llvm.fshl and llvm.fshr if they are available (LLVM >= 7).
Originally I wanted to expose the funnel_shift_left and
funnel_shift_right intrinsics and implement rotate_left and
rotate_right on top of them. However, emulation of funnel
shifts requires emitting a conditional to check for zero shift
amount, which is not necessary for rotates. I was uncomfortable
doing that here, as I don't want to rely on LLVM to optimize
away that conditional (and for variable rotates, I'm not sure it
can). We should revisit that question when we raise our minimum
version requirement to LLVM 7 and don't need emulation code
anymore.
Rename `CoerceSized` to `DispatchFromDyn`, and reverse the direction so that, for example, you write
```
impl<T: Unsize<U>, U> DispatchFromDyn<*const U> for *const T {}
```
instead of
```
impl<T: Unsize<U>, U> DispatchFromDyn<*const T> for *const U {}
```
this way the trait is really just a subset of `CoerceUnsized`.
The checks in object_safety.rs are updated for the new trait, and some documentation and method names in there are updated for the new trait name — e.g. `receiver_is_coercible` is now called `receiver_is_dispatchable`. Since the trait now works in the opposite direction, some code had to updated here for that too.
I did not update the error messages for invalid `CoerceSized` (now `DispatchFromDyn`) implementations, except to find/replace `CoerceSized` with `DispatchFromDyn`. Will ask for suggestions in the PR thread.
This trait is more-or-less the reverse of CoerceUnsized, and will be
used for object-safety checks. Receiver types like `Rc` will have to
implement `CoerceSized` so that methods that use `Rc<Self>` as the
receiver will be considered object-safe.
Make a bunch of trivial methods of NonNull be `#[inline]`
I was seeing super trivial methods not getting inlined in some of my builds, so I went ahead and just marked all the methods inline where it seemed appropriate.
r? @SimonSapin
Add ManuallyDrop::take
Tracking issue: #55422
Proposed in this form in https://internals.rust-lang.org/t/mini-rfc-manuallydrop-take/8679,
see that thread for some history.
A small convenience wrapper for `ManuallyDrop` that makes a pattern (taking ownership of the contained data in drop) more obvious.
Custom E0277 diagnostic for `Path`
r? @nikomatsakis we have a way to target `Path` exclusively, we need to identify the correct text to show to consider #23286 fixed.
Add slice::rchunks(), rchunks_mut(), rchunks_exact() and rchunks_exact_mut()
These work exactly like the normal chunks iterators but start creating
chunks from the end of the slice.
----
The new iterators were motivated by a [comment](https://github.com/rust-lang/rust/issues/47115#issuecomment-424141121) by @DutchGhost.
~~~This currently includes the commits from https://github.com/rust-lang/rust/pull/54537 to not have to rename things twice or have merge conflicts. I'll force-push a new version of the branch ones those are in master.~~~
Also the stabilization tracking issue is just some number right now. I'll create the corresponding issue once this is reviewed and otherwise mergeable.
cc @DutchGhost
Add filtering option to `rustc_on_unimplemented` and reword `Iterator` E0277 errors
- Add more targetting filters for arrays to `rustc_on_unimplemented` (Fix#53766)
- Detect one element array of `Range` type, which is potentially a typo:
`for _ in [0..10] {}` where iterating between `0` and `10` was intended.
(Fix#23141)
- Suggest `.bytes()` and `.chars()` for `String`.
- Suggest borrowing or `.iter()` on arrays (Fix#36391)
- Suggest using range literal when iterating on integers (Fix#34353)
- Do not suggest `.iter()` by default (Fix#50773, fix#46806)
- Add regression test (Fix#22872)
clarify pointer add/sub function safety concerns
Ralf Jung made the same changes to the offset functions' documentation
in commit fb089156. As add/sub just call offset, the same limitation
applies here, as well.
I did not copy the whole explanation ("In particular, the resulting pointer may *not* be used to access a different allocated object [...]") because I'd consider that as being too repetitive. The documentation of add/sub already refers to the offset function, so people interested in the details can look it up, there.
But changing 'an object' to 'the same object' is a small change which improves clarity a lot.
During review of the previous commit, @joshtriplett noticed that
the emphasis on 'the same' is unnecessary. For consistency, remove it
on the offset() functions, as well.
Ralf Jung made the same changes to the offset functions' documentation
in commit fb089156. As add/sub just call offset, the same limitation
applies here, as well.
Removed emphasis on review request by @joshtriplett
