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.
Some Promotion Refactoring
Clean up promotion a bit:
* factor out some common code
* more exhaustive matches
This *should* not break anything... the only potentially-breaking change is that `BorrowKind::Shallow | BorrowKind::Unique` are now rejected for internal references.
r? ``@oli-obk``
Don't give an error when creating a file for the first time
Previously, `os.remove` would always give a FileNotFound error the first
time you called it, causing bootstrap to make unnecessary copies. This
now only calls `remove()` if the file exists, avoiding the unnecessary
error.
This is a pretty small cleanup but I think it's useful. Taken from https://github.com/rust-lang/rust/pull/79540.
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
remove empty wraps, don't return Results from from infallible functions
This makes code easier to understand because it is more obvious when a function actually can't fail (return Err or None)
Make functions that only ever return Some(x), return x directly
Remove return type from functions that return Option<(), Err> but would only ever return Ok(()).
Found with `clippy::unnecessary_wraps`
Revert "Cleanup markdown span handling"
Reverts rust-lang/rust#80244. This caused a diagnostic regression, originally it was:
```
warning: unresolved link to `std::process::Comman`
--> link.rs:3:10
|
3 | //! [a]: std::process::Comman
| ^^^^^^^^^^^^^^^^^^^^ no item named `Comman` in module `process`
|
= note: `#[warn(broken_intra_doc_links)]` on by default
```
but after that PR rustdoc now displays
```
warning: unresolved link to `std::process::Comman`
--> link.rs:1:14
|
1 | //! Links to [a] [link][a]
| ^^^ no item named `Comman` in module `process`
|
= note: `#[warn(broken_intra_doc_links)]` on by default
```
which IMO is much less clear.
cc `@bugadani,` thanks for catching this in https://github.com/rust-lang/rust/pull/77859.
r? `@GuillaumeGomez`
Improvements to NatVis support
NatVis files describe how to display types in some Windows debuggers,
such as Visual Studio, WinDbg, and VS Code.
This commit makes several improvements:
* Adds visualizers for Rc<T>, Weak<T>, and Arc<T>.
* Changes [size] to [len], for consistency with the Rust API.
Visualizers often use [size] to mirror the size() method on C++ STL
collections.
* Several visualizers used the PVOID and ULONG typedefs. These are part
of the Windows API; they are not guaranteed to always be defined in a
pure Rust DLL/EXE. I converted PVOID to `void*` and `ULONG` to
`unsigned long`.
* Cosmetic change: Removed {} braces around the visualized display
for `Option` types. They now display simply as `Some(value)` or
`None`, which reflects what is written in source code.
* The visualizer for `alloc::string::String` makes assumptions about
the layout of `String` (it casts `String*` to another type), rather
than using symbolic expressions. This commit changes the visualizer
so that it simply uses symbolic expressions to access the string
data and string length.
* The visualizers for `str` and `String` now place the character data
array under a synthetic `[chars]` node. When expanding a `String`
node, users rarely want to see an array of characters. This just places
them behind one expansion node / level.
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`.
remove unused return type of dropck::check_drop_obligations()
don't wrap return type in Option in get_macro_by_def_id() since we would always return Some(..)
remove redundant return type of back::write::optimize()
don't Option-wrap return type of compute_type_parameters() since we always return Some(..)
don't return empty Result in assemble_generator_candidates()
don't return empty Result in assemble_closure_candidates()
don't return empty result in assemble_fn_pointer_candidates()
don't return empty result in assemble_candidates_from_impls()
don't return empty result in assemble_candidates_from_auto_impls()
don't return emtpy result in assemble_candidates_for_trait_alias()
don't return empty result in assemble_builtin_bound_candidates()
don't return empty results in assemble_extension_candidates_for_traits_in_scope() and assemble_extension_candidates_for_trait()
remove redundant wrapping of return type of StripItem::strip() since it always returns Some(..)
remove unused return type of assemble_extension_candidates_for_all_traits()
Use sans-serif font for the "all items" page links
The "all items" pages' links aren't using a sans-serif font unlike the rest of equivalent items in the other module pages. ``@Nemo157`` reported me this issue so here is the fix!
r? ``@Nemo157``
Add llvm-libunwind change to bootstrap CHANGELOG
From #77703.
This doesn't need a `changelog-seen` version bump because the old values aren't accepted anymore, meaning anyone who was using this had to change it already.
r? ``@Mark-Simulacrum``
Edit rustc_span documentation
Various changes to the `rustc_span` docs, including the following:
- Additions to top-level docs
- Edits to the source_map module docs
- Edits to documentation for `Span` and `SpanData`
- Added intra-docs links
- Documentation for Levenshtein distances
- Fixed missing punctuation
Lint on redundant trailing semicolon after item
We now lint on code like this:
```rust
fn main() {
fn foo() {};
struct Bar {};
}
```
Previously, this caused warnings in Cargo, so it was disabled.
Replace pretty-print/compare/retokenize hack with targeted workarounds
Based on https://github.com/rust-lang/rust/pull/78296
cc https://github.com/rust-lang/rust/issues/43081
The 'pretty-print/compare/retokenize' hack is used to try to avoid passing an outdated `TokenStream` to a proc-macro when the underlying AST is modified in some way (e.g. cfg-stripping before derives). Unfortunately, retokenizing throws away spans (including hygiene information), which causes issues of its own. Every improvement to the accuracy of the pretty-print/retokenize comparison has resulted in non-trivial ecosystem breakage due to hygiene changes. In extreme cases, users deliberately wrote unhygienic `macro_rules!` macros (likely because they did not realize that the compiler's behavior was a bug).
Additionaly, the comparison between the original and pretty-printed/retoknized token streams comes at a non-trivial runtime cost, as shown by https://github.com/rust-lang/rust/pull/79338
This PR removes the pretty-print/compare/retokenize logic from `nt_to_tokenstream`. We only discard the original `TokenStream` under two circumstances:
* Inner attributes are used (detected by examining the AST)
* `cfg`/`cfg_attr` processing modifies the AST. This is detected by making the visitor update a flag when it performs a modification, instead of trying to detect the modification after-the-fact. Note that a 'matching' `cfg` (e.g. `#[cfg(not(FALSE)]`) does not actually get removed from the AST, allowing us to preserve the original `TokenStream`.
In all other cases, we preserve the original `TokenStream`.
This could use a bit of refactoring/renaming - opening for a Crater run.
r? `@ghost`
- Replace {} with the stringified expr
Giant thank you to `@danielhenrymantilla` for figuring out how to make
this work ❤️
- Note that this is just an approximation and it would be better to add
a doc-comment
Remove `compile-fail` test suite
By moving all of its tests to `ui` test suite.
Now we have directives like `// dont-check-compiler-stderr` that allow to disable `.stderr` comparison for platform-dependent tests without introducing a whole new test suite.
