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fix: Derive ParamEnv from GenericPredicates #21059

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Merged
merged 1 commit into from
Nov 19, 2025
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fix: Derive ParamEnv from GenericPredicates #21059

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5 changes: 0 additions & 5 deletions crates/hir-ty/src/generics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -60,11 +60,6 @@ impl Generics {
self.params.where_predicates().iter()
}

pub(crate) fn has_no_predicates(&self) -> bool {
self.params.has_no_predicates()
&& self.parent_generics.as_ref().is_none_or(|g| g.params.has_no_predicates())
}

pub(crate) fn is_empty(&self) -> bool {
self.params.is_empty() && self.parent_generics.as_ref().is_none_or(|g| g.params.is_empty())
}
Expand Down
112 changes: 15 additions & 97 deletions crates/hir-ty/src/lower.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1624,105 +1624,23 @@ pub(crate) fn trait_environment_query<'db>(
db: &'db dyn HirDatabase,
def: GenericDefId,
) -> Arc<TraitEnvironment<'db>> {
let generics = generics(db, def);
if generics.has_no_predicates() && generics.is_empty() {
return TraitEnvironment::empty(def.krate(db));
}

let resolver = def.resolver(db);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
generics.store(),
def,
LifetimeElisionKind::AnonymousReportError,
);
let mut traits_in_scope = Vec::new();
let mut clauses = Vec::new();
for maybe_parent_generics in
std::iter::successors(Some(&generics), |generics| generics.parent_generics())
{
ctx.store = maybe_parent_generics.store();
for pred in maybe_parent_generics.where_predicates() {
for pred in ctx.lower_where_predicate(pred, false, &generics, PredicateFilter::All) {
if let rustc_type_ir::ClauseKind::Trait(tr) = pred.kind().skip_binder() {
traits_in_scope.push((tr.self_ty(), tr.def_id().0));
}
clauses.push(pred);
}
}

push_const_arg_has_type_predicates(db, &mut clauses, maybe_parent_generics);
}

if let Some(trait_id) = def.assoc_trait_container(db) {
// add `Self: Trait<T1, T2, ...>` to the environment in trait
// function default implementations (and speculative code
// inside consts or type aliases)
cov_mark::hit!(trait_self_implements_self);
let trait_ref = TraitRef::identity(ctx.interner, trait_id.into());
let clause = Clause(Predicate::new(
ctx.interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(rustc_type_ir::ClauseKind::Trait(
TraitPredicate { trait_ref, polarity: rustc_type_ir::PredicatePolarity::Positive },
))),
));
clauses.push(clause);
}

let explicitly_unsized_tys = ctx.unsized_types;

let sized_trait = LangItem::Sized.resolve_trait(db, resolver.krate());
if let Some(sized_trait) = sized_trait {
let (mut generics, mut def_id) =
(crate::next_solver::generics::generics(db, def.into()), def);
loop {
let self_idx = trait_self_param_idx(db, def_id);
for (idx, p) in generics.own_params.iter().enumerate() {
if let Some(self_idx) = self_idx
&& p.index() as usize == self_idx
{
continue;
}
let GenericParamId::TypeParamId(param_id) = p.id else {
continue;
};
let idx = idx as u32 + generics.parent_count as u32;
let param_ty = Ty::new_param(ctx.interner, param_id, idx);
if explicitly_unsized_tys.contains(&param_ty) {
continue;
}
let trait_ref = TraitRef::new_from_args(
ctx.interner,
sized_trait.into(),
GenericArgs::new_from_iter(ctx.interner, [param_ty.into()]),
);
let clause = Clause(Predicate::new(
ctx.interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(
rustc_type_ir::ClauseKind::Trait(TraitPredicate {
trait_ref,
polarity: rustc_type_ir::PredicatePolarity::Positive,
}),
)),
));
clauses.push(clause);
}

if let Some(g) = generics.parent {
generics = crate::next_solver::generics::generics(db, g.into());
def_id = g;
} else {
break;
}
}
}

let clauses = rustc_type_ir::elaborate::elaborate(ctx.interner, clauses);
let clauses = Clauses::new_from_iter(ctx.interner, clauses);
let module = def.module(db);
let interner = DbInterner::new_with(db, Some(module.krate()), module.containing_block());
let predicates = GenericPredicates::query_all(db, def);
let traits_in_scope = predicates
.iter_identity_copied()
.filter_map(|pred| match pred.kind().skip_binder() {
ClauseKind::Trait(tr) => Some((tr.self_ty(), tr.def_id().0)),
_ => None,
})
.collect();
let clauses = rustc_type_ir::elaborate::elaborate(interner, predicates.iter_identity_copied());
let clauses = Clauses::new_from_iter(interner, clauses);
let env = ParamEnv { clauses };

TraitEnvironment::new(resolver.krate(), None, traits_in_scope.into_boxed_slice(), env)
// FIXME: We should normalize projections here, like rustc does.

TraitEnvironment::new(module.krate(), module.containing_block(), traits_in_scope, env)
}

#[derive(Copy, Clone, Debug, PartialEq, Eq)]
Expand Down
19 changes: 13 additions & 6 deletions crates/hir-ty/src/tests/incremental.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,12 @@ fn foo() -> i32 {
"body_shim",
"body_with_source_map_shim",
"trait_environment_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"lang_item",
"crate_lang_items",
"ImplTraits < 'db >::return_type_impl_traits_",
"expr_scopes_shim",
"lang_item",
"crate_lang_items",
]
"#]],
);
Expand Down Expand Up @@ -131,18 +133,21 @@ fn baz() -> i32 {
"body_shim",
"body_with_source_map_shim",
"trait_environment_shim",
"ImplTraits < 'db >::return_type_impl_traits_",
"expr_scopes_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"lang_item",
"crate_lang_items",
"attrs_shim",
"attrs_shim",
"ImplTraits < 'db >::return_type_impl_traits_",
"expr_scopes_shim",
"lang_item",
"infer_shim",
"function_signature_shim",
"function_signature_with_source_map_shim",
"body_shim",
"body_with_source_map_shim",
"trait_environment_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"ImplTraits < 'db >::return_type_impl_traits_",
"expr_scopes_shim",
"infer_shim",
Expand All @@ -151,6 +156,7 @@ fn baz() -> i32 {
"body_shim",
"body_with_source_map_shim",
"trait_environment_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"ImplTraits < 'db >::return_type_impl_traits_",
"expr_scopes_shim",
]
Expand Down Expand Up @@ -581,6 +587,7 @@ fn main() {
"body_shim",
"body_with_source_map_shim",
"trait_environment_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"lang_item",
"crate_lang_items",
"attrs_shim",
Expand All @@ -591,6 +598,7 @@ fn main() {
"function_signature_shim",
"function_signature_with_source_map_shim",
"trait_environment_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"ImplTraits < 'db >::return_type_impl_traits_",
"expr_scopes_shim",
"struct_signature_shim",
Expand All @@ -609,7 +617,6 @@ fn main() {
"impl_trait_with_diagnostics_shim",
"impl_self_ty_with_diagnostics_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"GenericPredicates < 'db >::query_with_diagnostics_",
"lang_item",
]
"#]],
Expand Down Expand Up @@ -677,7 +684,7 @@ fn main() {
"function_signature_shim",
"body_with_source_map_shim",
"body_shim",
"trait_environment_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"crate_lang_items",
"attrs_shim",
"attrs_shim",
Expand All @@ -686,6 +693,7 @@ fn main() {
"ImplTraits < 'db >::return_type_impl_traits_",
"infer_shim",
"function_signature_with_source_map_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"ImplTraits < 'db >::return_type_impl_traits_",
"expr_scopes_shim",
"struct_signature_with_source_map_shim",
Expand All @@ -699,7 +707,6 @@ fn main() {
"impl_trait_with_diagnostics_shim",
"impl_self_ty_with_diagnostics_shim",
"GenericPredicates < 'db >::query_with_diagnostics_",
"GenericPredicates < 'db >::query_with_diagnostics_",
]
"#]],
);
Expand Down
26 changes: 25 additions & 1 deletion crates/hir-ty/src/tests/traits.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -349,7 +349,6 @@ fn test() {

#[test]
fn trait_default_method_self_bound_implements_trait() {
cov_mark::check!(trait_self_implements_self);
check(
r#"
trait Trait {
Expand Down Expand Up @@ -5032,3 +5031,28 @@ fn main() {
"#]],
);
}

#[test]
fn implicit_sized_bound_on_param() {
check(
r#"
//- minicore: sized
struct PBox<T, A>(T, A);

impl<T, A> PBox<T, A> {
fn token_with(self) {}
}

trait MoveMessage {
fn token<A>(self, alloc: A)
where
Self: Sized,
{
let b = PBox::<Self, A>(self, alloc);
b.token_with();
// ^^^^^^^^^^^^^^ type: ()
}
}
"#,
);
}
2 changes: 1 addition & 1 deletion crates/ide-completion/src/tests/flyimport.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -780,9 +780,9 @@ fn main() {
}
"#,
expect![[r#"
me random_method(…) (use dep::test_mod::TestTrait) fn(&self) DEPRECATED
ct SPECIAL_CONST (use dep::test_mod::TestTrait) u8 DEPRECATED
fn weird_function() (use dep::test_mod::TestTrait) fn() DEPRECATED
me random_method(…) (use dep::test_mod::TestTrait) fn(&self) DEPRECATED
"#]],
);
}
Expand Down