const_eval: allow function pointer signatures containing &mut T in const contexts
potentially fixes#114994
We utilize a `TypeVisitor` here in order to more easily handle control flow.
- In the event the typekind the Visitor sees is a function pointer, we skip over it
- However, otherwise we do one of two things:
- If we find a mutable reference, check it, then continue visiting types
- If we find any other type, continue visiting types
This means we will check if the function pointer _itself_ is mutable, but not if any of the types _within_ are.
const-eval: make misalignment a hard error
It's been a future-incompat error (showing up in cargo's reports) since https://github.com/rust-lang/rust/pull/104616, Rust 1.68, released in March. That should be long enough.
The question for the lang team is simply -- should we move ahead with this, making const-eval alignment failures a hard error? (It turns out some of them accidentally already were hard errors since #104616. But not all so this is still a breaking change. Crater found no regression.)
improve the suggestion of `generic_bound_failure`
- Fixes#115375
- suggest the bound in the correct scope: trait or impl header vs assoc item. See `tests/ui/suggestions/lifetimes/type-param-bound-scope.rs`
- don't suggest a lifetime name that conflicts with the other late-bound regions of the function:
```rust
type Inv<'a> = *mut &'a ();
fn check_bound<'a, T: 'a>(_: T, _: Inv<'a>) {}
fn test<'a, T>(_: &'a str, t: T, lt: Inv<'_>) { // suggests a new name `'a`
check_bound(t, lt); //~ ERROR
}
```
Add a note to duplicate diagnostics
Helps explain why there may be a difference between manual testing and the test suite output and highlights them as something to potentially look into
For existing duplicate diagnostics I just blessed them other than a few files that had other `NOTE` annotations in
Correctly deny late-bound lifetimes from parent in anon consts and TAITs
Reuse the `AnonConstBoundary` scope (introduced in #108553, renamed in this PR to `LateBoundary`) to deny late-bound vars of *all* kinds (ty/const/lifetime) in anon consts and TAITs.
Side-note, but I would like to consolidate this with the error reporting for RPITs (E0657):
c4f25777a0/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs (L733-L754) but the semantics about what we're allowed to capture there are slightly different, so I'm leaving that untouched.
Fixes#115474
Don't require `Drop` for `[PhantomData<T>; N]` where `N` and `T` are generic, if `T` requires `Drop`
fixes https://github.com/rust-lang/rust/issues/115403
fixes https://github.com/rust-lang/rust/issues/115410
This was accidentally regressed in https://github.com/rust-lang/rust/pull/114134, because it was accidentally stabilized in #102204 (cc `@rust-lang/lang,` seems like an innocent stabilization, considering this PR is more of a bugfix than a feature).
While we have a whole month to beta backport this change before the regression hits stable, I'd still prefer not to go through an FCP on this PR (which fixes a regression), if T-lang wants an FCP, I can can open an issue about the change itself.
remove some unnecessary ignore-debug clauses
ignore-debug is only needed when the debug assertions *in the standard library* somehow affect the test. This can happen with inlining but otherwise should be rare. ignore-debug is problematic since PR CI is only run with debug assertions.
r? `@cjgillot` since it looks like you added most of these
