Do not create dangling &T in Weak<T>::drop
Since at this point all strong pointers have been dropped, the wrapped `T` has also been dropped. As such, creating a `&T` to the dropped place is negligent at best (language UB at worst). Since we have `Layout::for_value_raw` now, use that instead of `Layout::for_value` to avoid creating the `&T`.
This does have implications for custom (potentially thin) DSTs, though much less severe than those discussed in #80407. Specifically, one of two things has to be true:
- It has to be possible to use a `*const T` to a dropped (potentially custom, potentially thin) unsized tailed object to determine the layout (size/align) of the object. This is what is currently implemented (though with `&T` instead of `&T`). The validity of reading some location after it has been dropped is an open question IIUC (https://github.com/rust-lang/unsafe-code-guidelines/issues/188) (except when the whole type is `Copy`, per `drop_in_place`'s docs).
In this design, custom DSTs would get a `*mut T` and use that to return layout, and must be able to do so while in the "zombie" (post-drop, pre-free) state.
- `RcBox`/`ArcInner` compute and store layout eagerly, so that they don't have to ask the type for its layout after dropping it.
Importantly, this is already true today, as you can construct `Rc<DST>`, create a `Weak<DST>`, and drop the `Rc` before the `Weak`. This PR is a strict improvement over the status quo, and the above question about potentially thin DSTs will need to be resolved by any custom DST proposal.
refactor: removing library/alloc/src/vec/mod.rs ignore-tidy-filelength
This PR removes the need for ignore-tidy-filelength for library/alloc/src/vec/mod.rs which is part of the issue #60302
It is probably easiest to review this PR by looking at it commit by commit rather than looking at the overall diff.
Rollup of 7 pull requests
Successful merges:
- #80185 (Fix ICE when pointing at multi bytes character)
- #80260 (slightly more typed interface to panic implementation)
- #80311 (Improvements to NatVis support)
- #80337 (Use `desc` as a doc-comment for queries if there are no doc comments)
- #80381 (Revert "Cleanup markdown span handling")
- #80492 (remove empty wraps, don't return Results from from infallible functions)
- #80509 (where possible, pass slices instead of &Vec or &String (clippy::ptr_arg))
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
slightly more typed interface to panic implementation
The panic payload is currently being passed around as a `usize`. However, it actually is a pointer, and the involved types are available on all ends of this API, so I propose we use the proper pointer type to avoid some casts. Avoiding int-to-ptr casts also makes this code work with `miri -Zmiri-track-raw-pointers`.
Add "chr" as doc alias to char::from_u32
Many programming languages provide a function called `chr` - Perl, Python, PHP, Visual Basic, SQL. This change makes `char::from_u32` easier to discover in the documentation.
`ord` is not added as its name conflicts with `Ord` trait, and it's not exactly clear what it could point to (`<u32 as From<char>>::from`?). I don't think it's exactly necessary, as `char::from_u32` documentation page says you can do reverse conversion with `as` operator anyway.
Add "length" as doc alias to len methods
Currently when searching for `length` there are no results: https://doc.rust-lang.org/std/?search=length. This makes `len` methods appear when searching for `length`.
Fix intra-doc links for non-path primitives
This does *not* currently work for associated items that are
auto-implemented by the compiler (e.g. `never::eq`), because they aren't
present in the source code. I plan to fix this in a follow-up PR.
Fixes https://github.com/rust-lang/rust/issues/63351 using the approach mentioned in https://github.com/rust-lang/rust/issues/63351#issuecomment-683352130.
r? `@Manishearth`
cc `@petrochenkov` - this makes `rustc_resolve::Res` public, is that ok? I'd just add an identical type alias in rustdoc if not, which seems a waste.
