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Rollup merge of #119540 - fmease:no-effect-args-inside-dyn-trait, r=compiler-errors

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Don't synthesize host effect args inside trait object types

While we were indeed emitting an error for `~const` & `const` trait bounds in trait object types, we were still synthesizing host effect args for them.

Since we don't record the original trait bound modifiers for dyn-Trait in `hir::TyKind::TraitObject` (unlike we do for let's say impl-Trait, `hir::TyKind::OpaqueTy`), AstConv just assumes `ty::BoundConstness::NotConst` in `conv_object_ty_poly_trait_ref` which given `<host> dyn ~const NonConstTrait` resulted in us not realizing that `~const` was used on a non-const trait which lead to a failed assertion in the end.

Instead of updating `hir::TyKind::TraitObject` to track this kind of information, just strip the user-provided constness (similar to #119505).

Fixes #119524.
This commit is contained in:
Matthias Krüger
2024-01-04 08:33:26 +01:00
committed by GitHub
parent 0db26e081d 695a02e0d8
commit f4335a419f
3 changed files with 47 additions and 15 deletions
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28
compiler/rustc_ast_lowering/src/lib.rs
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@@ -1434,19 +1434,21 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
let (bounds, lifetime_bound) = self.with_dyn_type_scope(true, |this| {
let bounds =
this.arena.alloc_from_iter(bounds.iter().filter_map(|bound| match bound {
GenericBound::Trait(
ty,
TraitBoundModifiers {
polarity: BoundPolarity::Positive | BoundPolarity::Negative(_),
constness,
},
) => Some(this.lower_poly_trait_ref(ty, itctx, *constness)),
// We can safely ignore constness here, since AST validation
// will take care of invalid modifier combinations.
GenericBound::Trait(
_,
TraitBoundModifiers { polarity: BoundPolarity::Maybe(_), .. },
) => None,
// We can safely ignore constness here since AST validation
// takes care of rejecting invalid modifier combinations and
// const trait bounds in trait object types.
GenericBound::Trait(ty, modifiers) => match modifiers.polarity {
BoundPolarity::Positive | BoundPolarity::Negative(_) => {
Some(this.lower_poly_trait_ref(
ty,
itctx,
// Still, don't pass along the constness here; we don't want to
// synthesize any host effect args, it'd only cause problems.
ast::BoundConstness::Never,
))
}
BoundPolarity::Maybe(_) => None,
},
GenericBound::Outlives(lifetime) => {
if lifetime_bound.is_none() {
lifetime_bound = Some(this.lower_lifetime(lifetime));