Fix the ffi_unwind_calls lint documentation
This fixes the [`ffi_unwind_calls`](https://doc.rust-lang.org/nightly/rustc/lints/listing/allowed-by-default.html#ffi-unwind-calls) documentation to show its output correctly. Currently it is showing the text `{{produces}}` which is not how it should look.
This fixes it by not ignoring the example. I'm not sure why it was ignored, as the way the lint currently works it doesn't seem to require external linkage. This also fixes several mistakes in the example:
* There is no `ffi_unwind_calls` feature.
* Denies the lint (which is otherwise allow be default).
* Removes the `mod impl` which is not valid Rust syntax, and doesn't appear to be needed anyways.
The output now looks like:
```
warning: call to foreign function with FFI-unwind ABI
--> lint_example.rs:10:14
|
10 | unsafe { foo(); }
| ^^^^^ call to foreign function with FFI-unwind ABI
|
note: the lint level is defined here
--> lint_example.rs:2:9
|
2 | #![warn(ffi_unwind_calls)]
| ^^^^^^^^^^^^^^^^
warning: call to function pointer with FFI-unwind ABI
--> lint_example.rs:12:14
|
12 | unsafe { ptr(); }
| ^^^^^ call to function pointer with FFI-unwind ABI
```
This also includes some updates to the lint-docs tool to help with this issue:
* Adds a check if a lint documentation has `{{produces}}` with an ignored example, and generates an error.
* All instances of a lint are now displayed. Previously it only showed the first time the lint fires. Some examples may trigger a lint multiple times, and they are all now displayed.
Ensure `ptr::read` gets all the same LLVM `load` metadata that dereferencing does
I was looking into `array::IntoIter` optimization, and noticed that it wasn't annotating the loads with `noundef` for simple things like `array::IntoIter<i32, N>`. Trying to narrow it down, it seems that was because `MaybeUninit::assume_init_read` isn't marking the load as initialized (<https://rust.godbolt.org/z/Mxd8TPTnv>), which is unfortunate since that's basically its reason to exist.
The root cause is that `ptr::read` is currently implemented via the *untyped* `copy_nonoverlapping`, and thus the `load` doesn't get any type-aware metadata: no `noundef`, no `!range`. This PR solves that by lowering `ptr::read(p)` to `copy *p` in MIR, for which the backends already do the right thing.
Fortuitiously, this also improves the IR we give to LLVM for things like `mem::replace`, and fixes a couple of long-standing bugs where `ptr::read` on `Copy` types was worse than `*`ing them.
Zulip conversation: <https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Move.20array.3A.3AIntoIter.20to.20ManuallyDrop/near/341189936>
cc `@erikdesjardins` `@JakobDegen` `@workingjubilee` `@the8472`
Fixes#106369Fixes#73258
I was looking into `array::IntoIter` optimization, and noticed that it wasn't annotating the loads with `noundef` for simple things like `array::IntoIter<i32, N>`.
Turned out to be a more general problem as `MaybeUninit::assume_init_read` isn't marking the load as initialized (<https://rust.godbolt.org/z/Mxd8TPTnv>), which is unfortunate since that's basically its reason to exist.
This PR lowers `ptr::read(p)` to `copy *p` in MIR, which fortuitiously also improves the IR we give to LLVM for things like `mem::replace`.
Querify register_tools and post-expansion early lints
The 2 extra queries correspond to code that happen before and after macro expansion, and don't need the resolver to exist.
Currently, deriving on packed structs has some non-trivial limitations,
related to the fact that taking references on unaligned fields is UB.
The current approach to field accesses in derived code:
- Normal case: `&self.0`
- In a packed struct that derives `Copy`: `&{self.0}`
- In a packed struct that doesn't derive `Copy`: `&self.0`
Plus, we disallow deriving any builtin traits other than `Default` for any
packed generic type, because it's possible that there might be
misaligned fields. This is a fairly broad restriction.
Plus, we disallow deriving any builtin traits other than `Default` for most
packed types that don't derive `Copy`. (The exceptions are those where the
alignments inherently satisfy the packing, e.g. in a type with
`repr(packed(N))` where all the fields have alignments of `N` or less
anyway. Such types are pretty strange, because the `packed` attribute is
not having any effect.)
This commit introduces a new, simpler approach to field accesses:
- Normal case: `&self.0`
- In a packed struct: `&{self.0}`
In the latter case, this requires that all fields impl `Copy`, which is
a new restriction. This means that the following example compiles under
the old approach and doesn't compile under the new approach.
```
#[derive(Debug)]
struct NonCopy(u8);
#[derive(Debug)
#[repr(packed)]
struct MyType(NonCopy);
```
(Note that the old approach's support for cases like this was brittle.
Changing the `u8` to a `u16` would be enough to stop it working. So not
much capability is lost here.)
However, the other constraints from the old rules are removed. We can now
derive builtin traits for packed generic structs like this:
```
trait Trait { type A; }
#[derive(Hash)]
#[repr(packed)]
pub struct Foo<T: Trait>(T, T::A);
```
To allow this, we add a `T: Copy` bound in the derived impl and a `T::A:
Copy` bound in where clauses. So `T` and `T::A` must impl `Copy`.
We can now also derive builtin traits for packed structs that don't derive
`Copy`, so long as the fields impl `Copy`:
```
#[derive(Hash)]
#[repr(packed)]
pub struct Foo(u32);
```
This includes types that hand-impl `Copy` rather than deriving it, such as the
following, that show up in winapi-0.2:
```
#[derive(Clone)]
#[repr(packed)]
struct MyType(i32);
impl Copy for MyType {}
```
The new approach is simpler to understand and implement, and it avoids
the need for the `unsafe_derive_on_repr_packed` check.
One exception is required for backwards-compatibility: we allow `[u8]`
fields for now. There is a new lint for this,
`byte_slice_in_packed_struct_with_derive`.
Update wording of invalid_doc_attributes docs.
There was a typo in the original docs for `invalid_doc_attributes`. I felt it could use a little rewording to try to clarify the reasoning for the lint. Also, this adds the future-incompatible notice.
Rollup of 8 pull requests
Successful merges:
- #103418 (Add `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` to future-incompat report)
- #106113 (llvm-wrapper: adapt for LLVM API change)
- #106144 (Improve the documentation of `black_box`)
- #106578 (Label closure captures/generator locals that make opaque types recursive)
- #106749 (Update cc to 1.0.77)
- #106935 (Fix `SingleUseLifetime` ICE)
- #107015 (Re-enable building rust-analyzer on riscv64)
- #107029 (Add new bootstrap members to triagebot.toml)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Revert "Make PROC_MACRO_DERIVE_RESOLUTION_FALLBACK a hard error"
This reverts commit 7d82cadd97 aka PR #84022
I am doing this to buy us some time with respect to issue #106337 w.r.t. the 1.67 release.
Use UnordMap and UnordSet for id collections (DefIdMap, LocalDefIdMap, etc)
This PR changes the `rustc_data_structures::define_id_collections!` macro to use `UnordMap` and `UnordSet` instead of `FxHashMap` and `FxHashSet`. This should account for a large portion of hash-maps being used in places where they can cause trouble.
The changes required are moderate but non-zero:
- In some places the collections are extracted into sorted vecs.
- There are a few instances where for-loops have been changed to extends.
~~Let's see what the performance impact is. With a bit more refactoring, we might be able to get rid of some of the additional sorting -- but the change set is already big enough. Unless there's a performance impact, I'd like to do further changes in subsequent PRs.~~
Performance does not seem to be negatively affected ([perf-run here](https://github.com/rust-lang/rust/pull/106977#issuecomment-1396776699)).
Part of [MCP 533](https://github.com/rust-lang/compiler-team/issues/533).
r? `@ghost`
make `order_dependent_trait_objects` show up in future-breakage reports
tried to change it to a hard error in #102474 but breaking the more than 1000 dependents of `traitobject` doesn't feel great 😅
This lint has existed since more than 3 years now and the way this is currently implemented is buggy and will break with #102472. imo we should upgrade it to also report for dependencies and maybe also backport this to beta. Then after maybe 2-3 stable versions I would like to finally convert this lint to a hard error.
