De-arc trait items query

crates/hir-def/src/db.rs

@@ -25,7 +25,7 @@ use crate::{
     import_map::ImportMap,
     item_tree::{ItemTree, file_item_tree_query},
     lang_item::{self, LangItem},
-    nameres::{assoc::TraitItems, crate_def_map, diagnostics::DefDiagnostics},
+    nameres::crate_def_map,
     signatures::{
         ConstSignature, EnumSignature, FunctionSignature, ImplSignature, StaticSignature,
         StructSignature, TraitAliasSignature, TraitSignature, TypeAliasSignature, UnionSignature,
@@ -119,13 +119,6 @@ pub trait DefDatabase: InternDatabase + ExpandDatabase + SourceDatabase {
         id: VariantId,
     ) -> (Arc<VariantFields>, Arc<ExpressionStoreSourceMap>);
 
-    #[salsa::transparent]
-    #[salsa::invoke(TraitItems::trait_items_query)]
-    fn trait_items(&self, e: TraitId) -> Arc<TraitItems>;
-
-    #[salsa::invoke(TraitItems::trait_items_with_diagnostics_query)]
-    fn trait_items_with_diagnostics(&self, tr: TraitId) -> (Arc<TraitItems>, DefDiagnostics);
-
     #[salsa::tracked]
     fn variant_fields(&self, id: VariantId) -> Arc<VariantFields> {
         self.variant_fields_with_source_map(id).0

crates/hir-def/src/import_map.rs

@@ -16,7 +16,7 @@ use crate::{
     AssocItemId, AttrDefId, Complete, FxIndexMap, ModuleDefId, ModuleId, TraitId,
     db::DefDatabase,
     item_scope::{ImportOrExternCrate, ItemInNs},
-    nameres::{DefMap, crate_def_map},
+    nameres::{DefMap, assoc::TraitItems, crate_def_map},
     visibility::Visibility,
 };
 
@@ -221,7 +221,7 @@ impl ImportMap {
         trait_import_info: &ImportInfo,
     ) {
         let _p = tracing::info_span!("collect_trait_assoc_items").entered();
-        for &(ref assoc_item_name, item) in &db.trait_items(tr).items {
+        for &(ref assoc_item_name, item) in &TraitItems::query(db, tr).items {
             let module_def_id = match item {
                 AssocItemId::FunctionId(f) => ModuleDefId::from(f),
                 AssocItemId::ConstId(c) => ModuleDefId::from(c),
@@ -482,7 +482,7 @@ mod tests {
     use expect_test::{Expect, expect};
     use test_fixture::WithFixture;
 
-    use crate::{ItemContainerId, Lookup, test_db::TestDB};
+    use crate::{ItemContainerId, Lookup, nameres::assoc::TraitItems, test_db::TestDB};
 
     use super::*;
 
@@ -580,7 +580,7 @@ mod tests {
 
         let trait_info = dependency_imports.import_info_for(ItemInNs::Types(trait_id.into()))?;
 
-        let trait_items = db.trait_items(trait_id);
+        let trait_items = TraitItems::query(db, trait_id);
         let (assoc_item_name, _) = trait_items
             .items
             .iter()

crates/hir-def/src/lang_item.rs

@@ -9,8 +9,10 @@ use triomphe::Arc;
 
 use crate::{
     AdtId, AssocItemId, AttrDefId, Crate, EnumId, EnumVariantId, FunctionId, ImplId, ModuleDefId,
-    StaticId, StructId, TraitId, TypeAliasId, UnionId, db::DefDatabase, expr_store::path::Path,
+    StaticId, StructId, TraitId, TypeAliasId, UnionId,
-    nameres::crate_def_map,
+    db::DefDatabase,
+    expr_store::path::Path,
+    nameres::{assoc::TraitItems, crate_def_map},
 };
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -113,7 +115,8 @@ pub fn crate_lang_items(db: &dyn DefDatabase, krate: Crate) -> Option<Box<LangIt
             match def {
                 ModuleDefId::TraitId(trait_) => {
                     lang_items.collect_lang_item(db, trait_, LangItemTarget::Trait);
-                    db.trait_items(trait_).items.iter().for_each(|&(_, assoc_id)| match assoc_id {
+                    TraitItems::query(db, trait_).items.iter().for_each(|&(_, assoc_id)| {
+                        match assoc_id {
                             AssocItemId::FunctionId(f) => {
                                 lang_items.collect_lang_item(db, f, LangItemTarget::Function);
                             }
@@ -121,6 +124,7 @@ pub fn crate_lang_items(db: &dyn DefDatabase, krate: Crate) -> Option<Box<LangIt
                                 lang_items.collect_lang_item(db, alias, LangItemTarget::TypeAlias)
                             }
                             AssocItemId::ConstId(_) => {}
+                        }
                     });
                 }
                 ModuleDefId::AdtId(AdtId::EnumId(e)) => {

crates/hir-def/src/lib.rs

@@ -89,7 +89,9 @@ use crate::{
     db::DefDatabase,
     hir::generics::{LocalLifetimeParamId, LocalTypeOrConstParamId},
     nameres::{
-        LocalDefMap, assoc::ImplItems, block_def_map, crate_def_map, crate_local_def_map,
+        LocalDefMap,
+        assoc::{ImplItems, TraitItems},
+        block_def_map, crate_def_map, crate_local_def_map,
         diagnostics::DefDiagnostics,
     },
     signatures::{EnumVariants, InactiveEnumVariantCode, VariantFields},
@@ -282,6 +284,13 @@ impl_intern!(StaticId, StaticLoc, intern_static, lookup_intern_static);
 pub type TraitLoc = ItemLoc<ast::Trait>;
 impl_intern!(TraitId, TraitLoc, intern_trait, lookup_intern_trait);
 
+impl TraitId {
+    #[inline]
+    pub fn trait_items(self, db: &dyn DefDatabase) -> &TraitItems {
+        TraitItems::query(db, self)
+    }
+}
+
 pub type TraitAliasLoc = ItemLoc<ast::TraitAlias>;
 impl_intern!(TraitAliasId, TraitAliasLoc, intern_trait_alias, lookup_intern_trait_alias);
 

crates/hir-def/src/nameres/assoc.rs

@@ -38,16 +38,18 @@ pub struct TraitItems {
     pub macro_calls: ThinVec<(AstId<ast::Item>, MacroCallId)>,
 }
 
+#[salsa::tracked]
 impl TraitItems {
     #[inline]
-    pub(crate) fn trait_items_query(db: &dyn DefDatabase, tr: TraitId) -> Arc<TraitItems> {
+    pub(crate) fn query(db: &dyn DefDatabase, tr: TraitId) -> &TraitItems {
-        db.trait_items_with_diagnostics(tr).0
+        &Self::query_with_diagnostics(db, tr).0
     }
 
-    pub(crate) fn trait_items_with_diagnostics_query(
+    #[salsa::tracked(returns(ref))]
+    pub fn query_with_diagnostics(
         db: &dyn DefDatabase,
         tr: TraitId,
-    ) -> (Arc<TraitItems>, DefDiagnostics) {
+    ) -> (TraitItems, DefDiagnostics) {
         let ItemLoc { container: module_id, id: ast_id } = tr.lookup(db);
 
         let collector =
@@ -55,7 +57,7 @@ impl TraitItems {
         let source = ast_id.with_value(collector.ast_id_map.get(ast_id.value)).to_node(db);
         let (items, macro_calls, diagnostics) = collector.collect(source.assoc_item_list());
 
-        (Arc::new(TraitItems { macro_calls, items }), DefDiagnostics::new(diagnostics))
+        (TraitItems { macro_calls, items }, DefDiagnostics::new(diagnostics))
     }
 
     pub fn associated_types(&self) -> impl Iterator<Item = TypeAliasId> + '_ {

crates/hir-def/src/nameres/collector.rs

@@ -41,6 +41,7 @@ use crate::{
     macro_call_as_call_id,
     nameres::{
         BuiltinShadowMode, DefMap, LocalDefMap, MacroSubNs, ModuleData, ModuleOrigin, ResolveMode,
+        assoc::TraitItems,
         attr_resolution::{attr_macro_as_call_id, derive_macro_as_call_id},
         crate_def_map,
         diagnostics::DefDiagnostic,
@@ -1020,8 +1021,7 @@ impl<'db> DefCollector<'db> {
                         let resolutions = if true {
                             vec![]
                         } else {
-                            self.db
+                            TraitItems::query(self.db, it)
-                                .trait_items(it)
                                 .items
                                 .iter()
                                 .map(|&(ref name, variant)| {

crates/hir-def/src/nameres/path_resolution.rs

@@ -24,8 +24,8 @@ use crate::{
     item_scope::{BUILTIN_SCOPE, ImportOrExternCrate},
     item_tree::FieldsShape,
     nameres::{
-        BlockInfo, BuiltinShadowMode, DefMap, LocalDefMap, MacroSubNs, crate_def_map,
+        BlockInfo, BuiltinShadowMode, DefMap, LocalDefMap, MacroSubNs, assoc::TraitItems,
-        sub_namespace_match,
+        crate_def_map, sub_namespace_match,
     },
     per_ns::PerNs,
     visibility::{RawVisibility, Visibility},
@@ -584,8 +584,11 @@ impl DefMap {
                     // now resulting in a cycle.
                     // To properly implement this, trait item collection needs to be done in def map
                     // collection...
-                    let item =
+                    let item = if true {
-                        if true { None } else { db.trait_items(t).assoc_item_by_name(segment) };
+                        None
+                    } else {
+                        TraitItems::query(db, t).assoc_item_by_name(segment)
+                    };
                     return match item {
                         Some(item) => ResolvePathResult::new(
                             match item {

crates/hir-ty/src/autoderef.rs

@@ -208,7 +208,7 @@ pub(crate) fn deref_by_trait(
     };
     let trait_id = trait_id()?;
     let target =
-        db.trait_items(trait_id).associated_type_by_name(&Name::new_symbol_root(sym::Target))?;
+        trait_id.trait_items(db).associated_type_by_name(&Name::new_symbol_root(sym::Target))?;
 
     let projection = {
         let b = TyBuilder::subst_for_def(db, trait_id, None);

crates/hir-ty/src/chalk_db.rs

@@ -315,9 +315,8 @@ impl chalk_solve::RustIrDatabase<Interner> for ChalkContext<'_> {
             crate::ImplTraitId::AsyncBlockTypeImplTrait(..) => {
                 if let Some((future_trait, future_output)) =
                     LangItem::Future.resolve_trait(self.db, self.krate).and_then(|trait_| {
-                        let alias = self
+                        let alias = trait_
-                            .db
+                            .trait_items(self.db)
-                            .trait_items(trait_)
                             .associated_type_by_name(&Name::new_symbol_root(sym::Output))?;
                         Some((trait_, alias))
                     })
@@ -711,7 +710,7 @@ pub(crate) fn trait_datum_query(
     };
     let where_clauses = convert_where_clauses(db, trait_.into(), &bound_vars);
     let associated_ty_ids =
-        db.trait_items(trait_).associated_types().map(to_assoc_type_id).collect();
+        trait_.trait_items(db).associated_types().map(to_assoc_type_id).collect();
     let trait_datum_bound = rust_ir::TraitDatumBound { where_clauses };
     let well_known = db.lang_attr(trait_.into()).and_then(well_known_trait_from_lang_item);
     let trait_datum = TraitDatum {
@@ -879,7 +878,7 @@ fn impl_def_datum(db: &dyn HirDatabase, krate: Crate, impl_id: hir_def::ImplId)
     let polarity = if negative { rust_ir::Polarity::Negative } else { rust_ir::Polarity::Positive };
 
     let impl_datum_bound = rust_ir::ImplDatumBound { trait_ref, where_clauses };
-    let trait_data = db.trait_items(trait_);
+    let trait_data = trait_.trait_items(db);
     let associated_ty_value_ids = impl_id
         .impl_items(db)
         .items
@@ -931,8 +930,9 @@ fn type_alias_associated_ty_value(
         .into_value_and_skipped_binders()
         .0; // we don't return any assoc ty values if the impl'd trait can't be resolved
 
-    let assoc_ty = db
+    let assoc_ty = trait_ref
-        .trait_items(trait_ref.hir_trait_id())
+        .hir_trait_id()
+        .trait_items(db)
         .associated_type_by_name(&type_alias_data.name)
         .expect("assoc ty value should not exist"); // validated when building the impl data as well
     let (ty, binders) = db.ty(type_alias.into()).into_value_and_skipped_binders();

crates/hir-ty/src/diagnostics/expr.rs

@@ -494,7 +494,7 @@ impl FilterMapNextChecker {
                 Some(next_function_id),
                 match next_function_id.lookup(db).container {
                     ItemContainerId::TraitId(iterator_trait_id) => {
-                        let iterator_trait_items = &db.trait_items(iterator_trait_id).items;
+                        let iterator_trait_items = &iterator_trait_id.trait_items(db).items;
                         iterator_trait_items.iter().find_map(|(name, it)| match it {
                             &AssocItemId::FunctionId(id) if *name == sym::filter_map => Some(id),
                             _ => None,

crates/hir-ty/src/display.rs

@@ -1394,7 +1394,7 @@ impl HirDisplay for Ty {
                         let future_trait =
                             LangItem::Future.resolve_trait(db, body.module(db).krate());
                         let output = future_trait.and_then(|t| {
-                            db.trait_items(t)
+                            t.trait_items(db)
                                 .associated_type_by_name(&Name::new_symbol_root(sym::Output))
                         });
                         write!(f, "impl ")?;

crates/hir-ty/src/dyn_compatibility.rs

@@ -101,7 +101,7 @@ where
 
     // rustc checks for non-lifetime binders here, but we don't support HRTB yet
 
-    let trait_data = db.trait_items(trait_);
+    let trait_data = trait_.trait_items(db);
     for (_, assoc_item) in &trait_data.items {
         dyn_compatibility_violation_for_assoc_item(db, trait_, *assoc_item, cb)?;
     }
@@ -164,7 +164,7 @@ fn predicates_reference_self(db: &dyn HirDatabase, trait_: TraitId) -> bool {
 
 // Same as the above, `predicates_reference_self`
 fn bounds_reference_self(db: &dyn HirDatabase, trait_: TraitId) -> bool {
-    let trait_data = db.trait_items(trait_);
+    let trait_data = trait_.trait_items(db);
     trait_data
         .items
         .iter()

crates/hir-ty/src/infer.rs

@@ -1813,7 +1813,7 @@ impl<'db> InferenceContext<'db> {
     }
 
     fn resolve_output_on(&self, trait_: TraitId) -> Option<TypeAliasId> {
-        self.db.trait_items(trait_).associated_type_by_name(&Name::new_symbol_root(sym::Output))
+        trait_.trait_items(self.db).associated_type_by_name(&Name::new_symbol_root(sym::Output))
     }
 
     fn resolve_lang_trait(&self, lang: LangItem) -> Option<TraitId> {

crates/hir-ty/src/infer/closure.rs

@@ -1210,9 +1210,8 @@ impl InferenceContext<'_> {
                         if let Some(deref_trait) =
                             self.resolve_lang_item(LangItem::DerefMut).and_then(|it| it.as_trait())
                         {
-                            if let Some(deref_fn) = self
+                            if let Some(deref_fn) = deref_trait
-                                .db
+                                .trait_items(self.db)
-                                .trait_items(deref_trait)
                                 .method_by_name(&Name::new_symbol_root(sym::deref_mut))
                             {
                                 break 'b deref_fn == f;

crates/hir-ty/src/infer/expr.rs

@@ -654,9 +654,8 @@ impl InferenceContext<'_> {
                 match op {
                     UnaryOp::Deref => {
                         if let Some(deref_trait) = self.resolve_lang_trait(LangItem::Deref) {
-                            if let Some(deref_fn) = self
+                            if let Some(deref_fn) = deref_trait
-                                .db
+                                .trait_items(self.db)
-                                .trait_items(deref_trait)
                                 .method_by_name(&Name::new_symbol_root(sym::deref))
                             {
                                 // FIXME: this is wrong in multiple ways, subst is empty, and we emit it even for builtin deref (note that
@@ -813,9 +812,8 @@ impl InferenceContext<'_> {
                         self.table.new_lifetime_var(),
                     ));
                     self.write_expr_adj(*base, adj.into_boxed_slice());
-                    if let Some(func) = self
+                    if let Some(func) = index_trait
-                        .db
+                        .trait_items(self.db)
-                        .trait_items(index_trait)
                         .method_by_name(&Name::new_symbol_root(sym::index))
                     {
                         let subst = TyBuilder::subst_for_def(self.db, index_trait, None);
@@ -1148,7 +1146,7 @@ impl InferenceContext<'_> {
         let Some(trait_) = fn_x.get_id(self.db, self.table.trait_env.krate) else {
             return;
         };
-        let trait_data = self.db.trait_items(trait_);
+        let trait_data = trait_.trait_items(self.db);
         if let Some(func) = trait_data.method_by_name(&fn_x.method_name()) {
             let subst = TyBuilder::subst_for_def(self.db, trait_, None)
                 .push(callee_ty.clone())
@@ -1316,7 +1314,7 @@ impl InferenceContext<'_> {
 
         let trait_func = lang_items_for_bin_op(op).and_then(|(name, lang_item)| {
             let trait_id = self.resolve_lang_item(lang_item)?.as_trait()?;
-            let func = self.db.trait_items(trait_id).method_by_name(&name)?;
+            let func = trait_id.trait_items(self.db).method_by_name(&name)?;
             Some((trait_id, func))
         });
         let (trait_, func) = match trait_func {

crates/hir-ty/src/infer/mutability.rs

@@ -129,9 +129,8 @@ impl InferenceContext<'_> {
                         if let Some(index_trait) =
                             LangItem::IndexMut.resolve_trait(self.db, self.table.trait_env.krate)
                         {
-                            if let Some(index_fn) = self
+                            if let Some(index_fn) = index_trait
-                                .db
+                                .trait_items(self.db)
-                                .trait_items(index_trait)
                                 .method_by_name(&Name::new_symbol_root(sym::index_mut))
                             {
                                 *f = index_fn;
@@ -194,9 +193,8 @@ impl InferenceContext<'_> {
                             });
                             if is_mut_ptr {
                                 mutability = Mutability::Not;
-                            } else if let Some(deref_fn) = self
+                            } else if let Some(deref_fn) = deref_trait
-                                .db
+                                .trait_items(self.db)
-                                .trait_items(deref_trait)
                                 .method_by_name(&Name::new_symbol_root(sym::deref_mut))
                             {
                                 *f = deref_fn;

crates/hir-ty/src/infer/path.rs

@@ -278,7 +278,7 @@ impl InferenceContext<'_> {
     ) -> Option<(ValueNs, Substitution)> {
         let trait_ = trait_ref.hir_trait_id();
         let item =
-            self.db.trait_items(trait_).items.iter().map(|(_name, id)| *id).find_map(|item| {
+            trait_.trait_items(self.db).items.iter().map(|(_name, id)| *id).find_map(|item| {
                 match item {
                     AssocItemId::FunctionId(func) => {
                         if segment.name == &self.db.function_signature(func).name {

crates/hir-ty/src/infer/unify.rs

@@ -859,7 +859,7 @@ impl<'a> InferenceTable<'a> {
         ] {
             let krate = self.trait_env.krate;
             let fn_trait = fn_trait_name.get_id(self.db, krate)?;
-            let trait_data = self.db.trait_items(fn_trait);
+            let trait_data = fn_trait.trait_items(self.db);
             let output_assoc_type =
                 trait_data.associated_type_by_name(&Name::new_symbol_root(output_assoc_name))?;
 

crates/hir-ty/src/lib.rs

@@ -891,8 +891,8 @@ pub fn callable_sig_from_fn_trait(
 ) -> Option<(FnTrait, CallableSig)> {
     let krate = trait_env.krate;
     let fn_once_trait = FnTrait::FnOnce.get_id(db, krate)?;
-    let output_assoc_type = db
+    let output_assoc_type = fn_once_trait
-        .trait_items(fn_once_trait)
+        .trait_items(db)
         .associated_type_by_name(&Name::new_symbol_root(sym::Output))?;
 
     let mut table = InferenceTable::new(db, trait_env.clone());

crates/hir-ty/src/lower.rs

@@ -805,7 +805,7 @@ fn named_associated_type_shorthand_candidates<R>(
 ) -> Option<R> {
     let mut search = |t| {
         all_super_trait_refs(db, t, |t| {
-            let data = db.trait_items(t.hir_trait_id());
+            let data = t.hir_trait_id().trait_items(db);
 
             for (name, assoc_id) in &data.items {
                 if let AssocItemId::TypeAliasId(alias) = assoc_id {
@@ -957,7 +957,7 @@ pub(crate) fn generic_predicates_for_param_query(
                     };
 
                     all_super_traits(db, tr).iter().any(|tr| {
-                        db.trait_items(*tr).items.iter().any(|(name, item)| {
+                        tr.trait_items(db).items.iter().any(|(name, item)| {
                             matches!(item, AssocItemId::TypeAliasId(_)) && name == assoc_name
                         })
                     })

crates/hir-ty/src/lower/path.rs

@@ -173,7 +173,7 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
                         self.skip_resolved_segment();
                         let segment = self.current_or_prev_segment;
                         let found =
-                            self.ctx.db.trait_items(trait_).associated_type_by_name(segment.name);
+                            trait_.trait_items(self.ctx.db).associated_type_by_name(segment.name);
 
                         match found {
                             Some(associated_ty) => {

crates/hir-ty/src/method_resolution.rs

@@ -1302,7 +1302,7 @@ fn iterate_trait_method_candidates(
         // trait, but if we find out it doesn't, we'll skip the rest of the
         // iteration
         let mut known_implemented = false;
-        for &(_, item) in db.trait_items(t).items.iter() {
+        for &(_, item) in t.trait_items(db).items.iter() {
             // Don't pass a `visible_from_module` down to `is_valid_candidate`,
             // since only inherent methods should be included into visibility checking.
             let visible =
@@ -1429,7 +1429,7 @@ fn iterate_inherent_methods(
     ) -> ControlFlow<()> {
         let db = table.db;
         for t in traits {
-            let data = db.trait_items(t);
+            let data = t.trait_items(db);
             for &(_, item) in data.items.iter() {
                 // We don't pass `visible_from_module` as all trait items should be visible.
                 let visible = match is_valid_trait_method_candidate(

crates/hir-ty/src/mir/eval.rs

@@ -657,12 +657,12 @@ impl Evaluator<'_> {
             cached_ptr_size,
             cached_fn_trait_func: LangItem::Fn
                 .resolve_trait(db, crate_id)
-                .and_then(|x| db.trait_items(x).method_by_name(&Name::new_symbol_root(sym::call))),
+                .and_then(|x| x.trait_items(db).method_by_name(&Name::new_symbol_root(sym::call))),
             cached_fn_mut_trait_func: LangItem::FnMut.resolve_trait(db, crate_id).and_then(|x| {
-                db.trait_items(x).method_by_name(&Name::new_symbol_root(sym::call_mut))
+                x.trait_items(db).method_by_name(&Name::new_symbol_root(sym::call_mut))
             }),
             cached_fn_once_trait_func: LangItem::FnOnce.resolve_trait(db, crate_id).and_then(|x| {
-                db.trait_items(x).method_by_name(&Name::new_symbol_root(sym::call_once))
+                x.trait_items(db).method_by_name(&Name::new_symbol_root(sym::call_once))
             }),
         })
     }
@@ -2808,7 +2808,7 @@ impl Evaluator<'_> {
     ) -> Result<()> {
         let Some(drop_fn) = (|| {
             let drop_trait = LangItem::Drop.resolve_trait(self.db, self.crate_id)?;
-            self.db.trait_items(drop_trait).method_by_name(&Name::new_symbol_root(sym::drop))
+            drop_trait.trait_items(self.db).method_by_name(&Name::new_symbol_root(sym::drop))
         })() else {
             // in some tests we don't have drop trait in minicore, and
             // we can ignore drop in them.
@@ -2918,7 +2918,7 @@ pub fn render_const_using_debug_impl(
         not_supported!("core::fmt::Debug not found");
     };
     let Some(debug_fmt_fn) =
-        db.trait_items(debug_trait).method_by_name(&Name::new_symbol_root(sym::fmt))
+        debug_trait.trait_items(db).method_by_name(&Name::new_symbol_root(sym::fmt))
     else {
         not_supported!("core::fmt::Debug::fmt not found");
     };

crates/hir-ty/src/mir/eval/shim.rs

@@ -1257,9 +1257,8 @@ impl Evaluator<'_> {
                     args.push(IntervalAndTy::new(addr, field, self, locals)?);
                 }
                 if let Some(target) = LangItem::FnOnce.resolve_trait(self.db, self.crate_id) {
-                    if let Some(def) = self
+                    if let Some(def) = target
-                        .db
+                        .trait_items(self.db)
-                        .trait_items(target)
                         .method_by_name(&Name::new_symbol_root(sym::call_once))
                     {
                         self.exec_fn_trait(

crates/hir-ty/src/mir/lower/as_place.rs

@@ -193,9 +193,8 @@ impl MirLowerCtx<'_> {
                                 if let Some(deref_trait) =
                                     self.resolve_lang_item(LangItem::DerefMut)?.as_trait()
                                 {
-                                    if let Some(deref_fn) = self
+                                    if let Some(deref_fn) = deref_trait
-                                        .db
+                                        .trait_items(self.db)
-                                        .trait_items(deref_trait)
                                         .method_by_name(&Name::new_symbol_root(sym::deref_mut))
                                     {
                                         break 'b deref_fn == f;
@@ -347,9 +346,8 @@ impl MirLowerCtx<'_> {
             .resolve_lang_item(trait_lang_item)?
             .as_trait()
             .ok_or(MirLowerError::LangItemNotFound(trait_lang_item))?;
-        let deref_fn = self
+        let deref_fn = deref_trait
-            .db
+            .trait_items(self.db)
-            .trait_items(deref_trait)
             .method_by_name(&trait_method_name)
             .ok_or(MirLowerError::LangItemNotFound(trait_lang_item))?;
         let deref_fn_op = Operand::const_zst(

crates/hir-ty/src/tests.rs

@@ -486,7 +486,7 @@ pub(crate) fn visit_module(
                     });
                 }
                 ModuleDefId::TraitId(it) => {
-                    let trait_data = db.trait_items(it);
+                    let trait_data = it.trait_items(db);
                     for &(_, item) in trait_data.items.iter() {
                         match item {
                             AssocItemId::FunctionId(it) => cb(it.into()),

crates/hir-ty/src/tests/incremental.rs

@@ -567,7 +567,7 @@ fn main() {
                 "ast_id_map_shim",
                 "parse_shim",
                 "real_span_map_shim",
-                "trait_items_with_diagnostics_shim",
+                "query_with_diagnostics_",
                 "body_shim",
                 "body_with_source_map_shim",
                 "attrs_shim",
@@ -674,7 +674,7 @@ fn main() {
                 "file_item_tree_query",
                 "real_span_map_shim",
                 "crate_local_def_map",
-                "trait_items_with_diagnostics_shim",
+                "query_with_diagnostics_",
                 "body_with_source_map_shim",
                 "attrs_shim",
                 "body_shim",

crates/hir-ty/src/utils.rs

@@ -218,7 +218,7 @@ pub(super) fn associated_type_by_name_including_super_traits(
     name: &Name,
 ) -> Option<(TraitRef, TypeAliasId)> {
     all_super_trait_refs(db, trait_ref, |t| {
-        let assoc_type = db.trait_items(t.hir_trait_id()).associated_type_by_name(name)?;
+        let assoc_type = t.hir_trait_id().trait_items(db).associated_type_by_name(name)?;
         Some((t, assoc_type))
     })
 }

crates/hir/src/attrs.rs

@@ -207,7 +207,7 @@ fn resolve_assoc_or_field(
             // Doc paths in this context may only resolve to an item of this trait
             // (i.e. no items of its supertraits), so we need to handle them here
             // independently of others.
-            return db.trait_items(id).items.iter().find(|it| it.0 == name).map(|(_, assoc_id)| {
+            return id.trait_items(db).items.iter().find(|it| it.0 == name).map(|(_, assoc_id)| {
                 let def = match *assoc_id {
                     AssocItemId::FunctionId(it) => ModuleDef::Function(it.into()),
                     AssocItemId::ConstId(it) => ModuleDef::Const(it.into()),

crates/hir/src/lib.rs

@@ -54,7 +54,7 @@ use hir_def::{
     },
     item_tree::ImportAlias,
     layout::{self, ReprOptions, TargetDataLayout},
-    nameres::{self, diagnostics::DefDiagnostic},
+    nameres::{self, assoc::TraitItems, diagnostics::DefDiagnostic},
     per_ns::PerNs,
     resolver::{HasResolver, Resolver},
     signatures::{ImplFlags, StaticFlags, TraitFlags, VariantFields},
@@ -649,7 +649,7 @@ impl Module {
                     acc.extend(def.diagnostics(db, style_lints))
                 }
                 ModuleDef::Trait(t) => {
-                    for diag in db.trait_items_with_diagnostics(t.id).1.iter() {
+                    for diag in TraitItems::query_with_diagnostics(db, t.id).1.iter() {
                         emit_def_diagnostic(db, acc, diag, edition);
                     }
 
@@ -822,7 +822,7 @@ impl Module {
 
             // Negative impls can't have items, don't emit missing items diagnostic for them
             if let (false, Some(trait_)) = (impl_is_negative, trait_) {
-                let items = &db.trait_items(trait_.into()).items;
+                let items = &trait_.id.trait_items(db).items;
                 let required_items = items.iter().filter(|&(_, assoc)| match *assoc {
                     AssocItemId::FunctionId(it) => !db.function_signature(it).has_body(),
                     AssocItemId::ConstId(id) => !db.const_signature(id).has_body(),
@@ -2883,7 +2883,7 @@ impl Trait {
     }
 
     pub fn function(self, db: &dyn HirDatabase, name: impl PartialEq<Name>) -> Option<Function> {
-        db.trait_items(self.id).items.iter().find(|(n, _)| name == *n).and_then(|&(_, it)| match it
+        self.id.trait_items(db).items.iter().find(|(n, _)| name == *n).and_then(|&(_, it)| match it
         {
             AssocItemId::FunctionId(id) => Some(Function { id }),
             _ => None,
@@ -2891,7 +2891,7 @@ impl Trait {
     }
 
     pub fn items(self, db: &dyn HirDatabase) -> Vec<AssocItem> {
-        db.trait_items(self.id).items.iter().map(|(_name, it)| (*it).into()).collect()
+        self.id.trait_items(db).items.iter().map(|(_name, it)| (*it).into()).collect()
     }
 
     pub fn items_with_supertraits(self, db: &dyn HirDatabase) -> Vec<AssocItem> {
@@ -2939,7 +2939,7 @@ impl Trait {
     }
 
     fn all_macro_calls(&self, db: &dyn HirDatabase) -> Box<[(AstId<ast::Item>, MacroCallId)]> {
-        db.trait_items(self.id).macro_calls.to_vec().into_boxed_slice()
+        self.id.trait_items(db).macro_calls.to_vec().into_boxed_slice()
     }
 
     /// `#[rust_analyzer::completions(...)]` mode.
@@ -5000,7 +5000,7 @@ impl<'db> Type<'db> {
         }
 
         let output_assoc_type =
-            db.trait_items(trait_).associated_type_by_name(&Name::new_symbol_root(sym::Output))?;
+            trait_.trait_items(db).associated_type_by_name(&Name::new_symbol_root(sym::Output))?;
         self.normalize_trait_assoc_type(db, &[], output_assoc_type.into())
     }
 
@@ -5013,8 +5013,8 @@ impl<'db> Type<'db> {
     /// This does **not** resolve `IntoIterator`, only `Iterator`.
     pub fn iterator_item(self, db: &'db dyn HirDatabase) -> Option<Type<'db>> {
         let iterator_trait = LangItem::Iterator.resolve_trait(db, self.env.krate)?;
-        let iterator_item = db
+        let iterator_item = iterator_trait
-            .trait_items(iterator_trait)
+            .trait_items(db)
             .associated_type_by_name(&Name::new_symbol_root(sym::Item))?;
         self.normalize_trait_assoc_type(db, &[], iterator_item.into())
     }
@@ -5044,8 +5044,8 @@ impl<'db> Type<'db> {
             return None;
         }
 
-        let into_iter_assoc_type = db
+        let into_iter_assoc_type = trait_
-            .trait_items(trait_)
+            .trait_items(db)
             .associated_type_by_name(&Name::new_symbol_root(sym::IntoIter))?;
         self.normalize_trait_assoc_type(db, &[], into_iter_assoc_type.into())
     }

crates/hir/src/semantics/child_by_source.rs

@@ -35,7 +35,7 @@ pub(crate) trait ChildBySource {
 
 impl ChildBySource for TraitId {
     fn child_by_source_to(&self, db: &dyn DefDatabase, res: &mut DynMap, file_id: HirFileId) {
-        let data = db.trait_items(*self);
+        let data = self.trait_items(db);
 
         data.macro_calls().filter(|(ast_id, _)| ast_id.file_id == file_id).for_each(
             |(ast_id, call_id)| {

crates/hir/src/source_analyzer.rs

@@ -1423,7 +1423,7 @@ impl<'db> SourceAnalyzer<'db> {
         method_name: &Name,
     ) -> Option<(TraitId, FunctionId)> {
         let trait_id = lang_trait.resolve_trait(db, self.resolver.krate())?;
-        let fn_id = db.trait_items(trait_id).method_by_name(method_name)?;
+        let fn_id = trait_id.trait_items(db).method_by_name(method_name)?;
         Some((trait_id, fn_id))
     }
 
@@ -1580,7 +1580,7 @@ fn resolve_hir_path_(
         // within the trait's associated types.
         if let (Some(unresolved), &TypeNs::TraitId(trait_id)) = (&unresolved, &ty) {
             if let Some(type_alias_id) =
-                db.trait_items(trait_id).associated_type_by_name(unresolved.name)
+                trait_id.trait_items(db).associated_type_by_name(unresolved.name)
             {
                 return Some(PathResolution::Def(ModuleDefId::from(type_alias_id).into()));
             }
@@ -1731,7 +1731,7 @@ fn resolve_hir_path_qualifier(
         // within the trait's associated types.
         if let (Some(unresolved), &TypeNs::TraitId(trait_id)) = (&unresolved, &ty) {
             if let Some(type_alias_id) =
-                db.trait_items(trait_id).associated_type_by_name(unresolved.name)
+                trait_id.trait_items(db).associated_type_by_name(unresolved.name)
             {
                 return Some(PathResolution::Def(ModuleDefId::from(type_alias_id).into()));
             }

crates/hir/src/symbols.rs

@@ -334,7 +334,7 @@ impl<'a> SymbolCollector<'a> {
     fn collect_from_trait(&mut self, trait_id: TraitId, trait_do_not_complete: Complete) {
         let trait_data = self.db.trait_signature(trait_id);
         self.with_container_name(Some(trait_data.name.as_str().into()), |s| {
-            for &(ref name, assoc_item_id) in &self.db.trait_items(trait_id).items {
+            for &(ref name, assoc_item_id) in &trait_id.trait_items(self.db).items {
                 s.push_assoc_item(assoc_item_id, name, Some(trait_do_not_complete));
             }
         });