Allow codegen to unsize `dyn*` to `dyn`
`dyn* Trait` is just another type that implements `Trait`, so we should be able to unsize `&dyn* Trait` into `&dyn Trait` perfectly fine, same for `Box` and other unsizeable types.
Fixes#106488
Prefer non-`[type error]` candidates during selection
Fixes#102130Fixes#106351
r? types
note: Alternatively we could filter out error where-clauses during param-env construction? But we still need to filter out impls with errors during `match_impl`, I think.
Fix invalid syntax and incomplete suggestion in impl Trait parameter type suggestions for E0311
Fixes#105544
The problems: The suggestion given for E0311 has invalid syntax when the synthetic type parameter is used for Trait type in function declaration:
```rust
fn foo(d: impl Sized) -> impl Sized
```
instead of explicitly specified like the following:
```rust
fn foo<T: Sized>(d: T) -> impl Sized
```
In addition to the syntax error, the suggestions given for E0311 are not complete when multiple elided lifetimes are involved in lifetime bounds, not all involved parameters are given the named lifetime in the suggestions. For the following test case:
```
fn foo(d: impl Sized, p: &mut ()) -> impl Sized + '_ {
(d, p)
}
```
a good suggestion should add the lifetime 'a to both d and p, instead of d only:
```
fn foo<'a>(d: impl Sized + 'a, p: &'a mut ()) -> impl Sized + '_ {
(d, p)
}
```
The Solution: Fix the syntax problem in the suggestions when synthetic type parameter is used, and also add lifetimes for all involved parameters.
Use CI LLVM in `test-various` builder
It was disabled because it needs `lld`, but since #104748 was merged it is no longer needed.
This will speed this test, since it no longer needs to build LLVM.
Recover from where clauses placed before tuple struct bodies
Open to any suggestions regarding the phrasing of the diagnostic.
Fixes#100790.
`@rustbot` label A-diagnostics
r? diagnostics
expl_impl_clone_on_copy: ignore packed structs with type/const params
changelog: [`expl_impl_clone_on_copy`]: Ignore `#[repr(packed)]` structs with type or const paramaters
Fixes#10188
A more involved solution that checks if any bound on the trait impl aren't present on the struct definition would be ideal, but I couldn't see a nice way to go about that
Note predicate span on `ImplDerivedObligation`
Seems obvious to point out the where-clause that introduces the `ImplDerivedObligation` :)
r? `@estebank`
