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Auto merge of #17939 - ShoyuVanilla:maybe-sized-fix, r=Veykril
fix: Wrong `Sized` predicate for `generic_predicates_for_param`
I found this gathers wrong `Self: Sized` bound while implementing object safety, though I couldn't find proper test for this.
If we call `generic_predicates_for_param` to `Bar` in the following code;
```rust
trait Foo<T: ?Sized> {}
trait Bar<T: Foo<Self> + ?Sized> {}
```
it returns `T: Sized` and `Self: Sized` bound, because normaly, the `?Sized` bound applied properly in L1059 with;
https://github.com/rust-lang/rust-analyzer/blob/3723e5910c14f0ffbd13de474b8a8fcc74db04ce/crates/hir-ty/src/lower.rs#L1035-L1061
But we filter them before it is lowered with that function here;
https://github.com/rust-lang/rust-analyzer/blob/3723e5910c14f0ffbd13de474b8a8fcc74db04ce/crates/hir-ty/src/lower.rs#L1540-L1586
So, the `?Sized` bounded params are not gathered into `ctx.unsized_types` and thus we are applying them implicit `Sized` bound here;
https://github.com/rust-lang/rust-analyzer/blob/3723e5910c14f0ffbd13de474b8a8fcc74db04ce/crates/hir-ty/src/lower.rs#L1591-L1602
| -rw-r--r-- | crates/hir-ty/src/lower.rs | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/crates/hir-ty/src/lower.rs b/crates/hir-ty/src/lower.rs index 5824c59c5a..58c34cbd9e 100644 --- a/crates/hir-ty/src/lower.rs +++ b/crates/hir-ty/src/lower.rs @@ -1551,6 +1551,10 @@ pub(crate) fn generic_predicates_for_param_query( } }; if invalid_target { + // If this is filtered out without lowering, `?Sized` is not gathered into `ctx.unsized_types` + if let TypeBound::Path(_, TraitBoundModifier::Maybe) = &**bound { + ctx.lower_where_predicate(pred, &def, true).for_each(drop); + } return false; } |