lower_trait: defer generic param collection to avoid query cycle

Author: sbillig

crates/hir-analysis/src/ty/trait_def.rs

@@ -24,7 +24,10 @@ use super::{
     unify::UnificationTable,
 };
 use crate::{
-    ty::{trait_lower::collect_trait_impls, trait_resolution::constraint::super_trait_cycle},
+    ty::{
+        trait_lower::collect_trait_impls, trait_resolution::constraint::super_trait_cycle,
+        ty_lower::collect_generic_params,
+    },
     HirAnalysisDb,
 };
 
@@ -310,16 +313,20 @@ impl<'db> TraitInstId<'db> {
 pub struct TraitDef<'db> {
     pub trait_: Trait<'db>,
     #[return_ref]
-    pub(crate) param_set: GenericParamTypeSet<'db>,
-    #[return_ref]
     pub methods: IndexMap<IdentId<'db>, TraitMethod<'db>>,
 }
 
+#[salsa::tracked]
 impl<'db> TraitDef<'db> {
     pub fn params(self, db: &'db dyn HirAnalysisDb) -> &'db [TyId<'db>] {
         self.param_set(db).params(db)
     }
 
+    #[salsa::tracked(return_ref)]
+    pub fn param_set(self, db: &'db dyn HirAnalysisDb) -> GenericParamTypeSet<'db> {
+        collect_generic_params(db, self.trait_(db).into())
+    }
+
     pub fn self_param(self, db: &'db dyn HirAnalysisDb) -> TyId<'db> {
         self.param_set(db).trait_self(db).unwrap()
     }

crates/hir-analysis/src/ty/trait_lower.rs

@@ -10,7 +10,7 @@ use super::{
     func_def::FuncDef,
     trait_def::{does_impl_trait_conflict, Implementor, TraitDef, TraitInstId, TraitMethod},
     ty_def::{InvalidCause, Kind, TyId},
-    ty_lower::{collect_generic_params, lower_generic_arg_list, GenericParamTypeSet},
+    ty_lower::{collect_generic_params, lower_generic_arg_list},
 };
 use crate::{
     name_resolution::{resolve_path, PathRes},
@@ -22,8 +22,6 @@ type TraitImplTable<'db> = FxHashMap<TraitDef<'db>, Vec<Binder<Implementor<'db>>
 
 #[salsa::tracked]
 pub(crate) fn lower_trait<'db>(db: &'db dyn HirAnalysisDb, trait_: Trait<'db>) -> TraitDef<'db> {
-    let param_set = collect_generic_params(db, trait_.into());
-
     let mut methods = IndexMap::<IdentId<'db>, TraitMethod<'db>>::default();
     for method in trait_.methods(db) {
         let Some(func) = lower_func(db, method) else {
@@ -36,7 +34,7 @@ pub(crate) fn lower_trait<'db>(db: &'db dyn HirAnalysisDb, trait_: Trait<'db>) -
         methods.entry(name).or_insert(trait_method);
     }
 
-    TraitDef::new(db, trait_, param_set, methods)
+    TraitDef::new(db, trait_, methods)
 }
 
 /// Collect all trait implementors in the ingot.

crates/hir-analysis/test_files/ty_check/associated_types.fe

@@ -1,17 +1,8 @@
 trait Abi {
-    type Selector: Encode<Self>
-    type Encoder
+    type Selector
 }
 
 struct SolAbi {}
 impl Abi for SolAbi {
     type Selector = [u8; 4]
 }
-
-trait Encode<A: Abi> {
-    fn encode(self, mut e: A::Encoder)
-}
-
-impl Encode<SolAbi> for [u8; 4] {
-    fn encode(self, mut e: SolAbi::Encoder) {}
-}

crates/hir-analysis/test_files/ty_check/associated_types_cycle.fe

@@ -0,0 +1,17 @@
+trait Abi {
+    type Selector: Encode<Self>
+    type Encoder
+}
+
+struct SolAbi {}
+impl Abi for SolAbi {
+    type Selector = [u8; 4]
+}
+
+trait Encode<A: Abi> {
+    fn encode(self, mut e: A::Encoder)
+}
+
+impl Encode<SolAbi> for [u8; 4] {
+    fn encode(self, mut e: SolAbi::Encoder) {}
+}