Commit Graph

8 Commits

Author SHA1 Message Date
Michael Goulet
4b23a224ab Label opaque type for 'captures lifetime' error message 2023-03-03 05:02:34 +00:00
Michael Howell
3f374128ee diagnostics: update test cases to refer to assoc fn with self as method 2023-02-22 08:40:47 -07:00
Esteban Küber
62ba3e70a1 Modify primary span label for E0308
The previous output was unintuitive to users.
2023-01-30 20:12:19 +00:00
Matthias Krüger
e0d71f500c
Rollup merge of #97373 - dimpolo:cell_dispatch_from_dyn, r=dtolnay
impl DispatchFromDyn for Cell and UnsafeCell

After some fruitful discussion on [Internals](https://internals.rust-lang.org/t/impl-dispatchfromdyn-for-cell-2/16520) here's my first PR to rust-lang/rust 🎉

Please let me know if there's something I missed.

This adds `DispatchFromDyn` impls for `Cell`, `UnsafeCell` and `SyncUnsafeCell`.
An existing test is also expanded to test the `Cell` impl (which requires the `UnsafeCell` impl)

The different `RefCell` types can not implement `DispatchFromDyn` since they have more than one (non ZST) field.

 

**Edit:**
### What:
These changes allow one to make types like `MyRc`(code below), to be object safe method receivers after implementing `DispatchFromDyn` and `Deref` for them.

This allows for code like this:
```rust
struct MyRc<T: ?Sized>(Cell<NonNull<RcBox<T>>>);

/* impls for DispatchFromDyn, CoerceUnsized and Deref for MyRc*/

trait Trait {
    fn foo(self: MyRc<Self>);
}

let impls_trait = ...;
let rc = MyRc::new(impls_trait) as MyRc<dyn Trait>;
rc.foo();
```

Note: `Cell` and `UnsafeCell` won't directly become valid method receivers since they don't implement `Deref`. Making use of these changes requires a wrapper type and nightly features.

### Why:
A custom pointer type with interior mutability allows one to store extra information in the pointer itself.
These changes allow for such a type to be a method receiver.

### Examples:
My use case is a cycle aware custom `Rc` implementation that when dropping a cycle marks some references dangling.

On the [forum](https://internals.rust-lang.org/t/impl-dispatchfromdyn-for-cell/14762/8) andersk mentioned that they track if a `Gc` reference is rooted with an extra bit in the reference itself.
2023-01-26 07:53:21 +01:00
dimi
a2d1cb2c22 impl DispatchFromDyn for Cell and UnsafeCell 2023-01-24 12:06:12 +01:00
Esteban Küber
656db98bd9 Tweak E0597
CC #99430
2023-01-15 19:46:20 +00:00
Esteban Küber
12ddf77811 When suggesting writing a fully qualified path probe for appropriate types
Fix #46585.
2023-01-11 21:30:10 +00:00
Albert Larsan
cf2dff2b1e
Move /src/test to /tests 2023-01-11 09:32:08 +00:00