19 files changed, 301 insertions, 160 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index cb990f4e2..c49190a0f 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -10,8 +10,10 @@ use hir_def::{
     adt::VariantData,
     body::scope::ExprScopes,
     builtin_type::BuiltinType,
+    traits::TraitData,
     type_ref::{Mutability, TypeRef},
-    CrateModuleId, ImplId, LocalEnumVariantId, LocalStructFieldId, ModuleId, UnionId,
+    AssocItemId, CrateModuleId, FunctionContainerId, HasModule, ImplId, LocalEnumVariantId,
+    LocalStructFieldId, Lookup, ModuleId, UnionId,
 };
 use hir_expand::{
     diagnostics::DiagnosticSink,
@@ -30,7 +32,6 @@ use crate::{
         TypeAliasId,
     },
     resolve::{Resolver, Scope, TypeNs},
-    traits::TraitData,
     ty::{InferenceResult, Namespace, TraitRef},
     Either, HasSource, ImportId, Name, ScopeDef, Source, Ty,
 };
@@ -230,15 +231,7 @@ impl Module {
 
     pub fn declarations(self, db: &impl DefDatabase) -> Vec<ModuleDef> {
         let def_map = db.crate_def_map(self.id.krate);
-        def_map[self.id.module_id]
-            .scope
-            .entries()
-            .filter_map(|(_name, res)| if res.import.is_none() { Some(res.def) } else { None })
-            .flat_map(|per_ns| {
-                per_ns.take_types().into_iter().chain(per_ns.take_values().into_iter())
-            })
-            .map(ModuleDef::from)
-            .collect()
+        def_map[self.id.module_id].scope.declarations().map(ModuleDef::from).collect()
     }
 
     pub fn impl_blocks(self, db: &impl DefDatabase) -> Vec<ImplBlock> {
@@ -655,7 +648,7 @@ impl FnData {
 
 impl Function {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        Module { id: self.id.module(db) }
+        self.id.lookup(db).module(db).into()
     }
 
     pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
@@ -688,21 +681,25 @@ impl Function {
 
     /// The containing impl block, if this is a method.
     pub fn impl_block(self, db: &impl DefDatabase) -> Option<ImplBlock> {
-        ImplBlock::containing(db, self.into())
+        match self.container(db) {
+            Some(Container::ImplBlock(it)) => Some(it),
+            _ => None,
+        }
     }
 
     /// The containing trait, if this is a trait method definition.
     pub fn parent_trait(self, db: &impl DefDatabase) -> Option<Trait> {
-        db.trait_items_index(self.module(db)).get_parent_trait(self.into())
+        match self.container(db) {
+            Some(Container::Trait(it)) => Some(it),
+            _ => None,
+        }
     }
 
     pub fn container(self, db: &impl DefDatabase) -> Option<Container> {
-        if let Some(impl_block) = self.impl_block(db) {
-            Some(impl_block.into())
-        } else if let Some(trait_) = self.parent_trait(db) {
-            Some(trait_.into())
-        } else {
-            None
+        match self.id.lookup(db).container {
+            FunctionContainerId::TraitId(it) => Some(Container::Trait(it.into())),
+            FunctionContainerId::ImplId(it) => Some(Container::ImplBlock(it.into())),
+            FunctionContainerId::ModuleId(_) => None,
         }
     }
 
@@ -757,7 +754,7 @@ impl Const {
     }
 
     pub fn parent_trait(self, db: &impl DefDatabase) -> Option<Trait> {
-        db.trait_items_index(self.module(db)).get_parent_trait(self.into())
+        db.trait_items_index(self.module(db).id).get_parent_trait(self.id.into()).map(Trait::from)
     }
 
     pub fn container(self, db: &impl DefDatabase) -> Option<Container> {
@@ -861,11 +858,11 @@ impl Trait {
     }
 
     pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
-        self.trait_data(db).name().clone()
+        self.trait_data(db).name.clone()
     }
 
     pub fn items(self, db: &impl DefDatabase) -> Vec<AssocItem> {
-        self.trait_data(db).items().to_vec()
+        self.trait_data(db).items.iter().map(|it| (*it).into()).collect()
     }
 
     fn direct_super_traits(self, db: &impl HirDatabase) -> Vec<Trait> {
@@ -912,10 +909,10 @@ impl Trait {
     pub fn associated_type_by_name(self, db: &impl DefDatabase, name: &Name) -> Option<TypeAlias> {
         let trait_data = self.trait_data(db);
         trait_data
-            .items()
+            .items
             .iter()
             .filter_map(|item| match item {
-                AssocItem::TypeAlias(t) => Some(*t),
+                AssocItemId::TypeAliasId(t) => Some(TypeAlias::from(*t)),
                 _ => None,
             })
             .find(|t| &t.name(db) == name)
@@ -930,7 +927,7 @@ impl Trait {
     }
 
     pub(crate) fn trait_data(self, db: &impl DefDatabase) -> Arc<TraitData> {
-        db.trait_data(self)
+        db.trait_data(self.id)
     }
 
     pub fn trait_ref(self, db: &impl HirDatabase) -> TraitRef {
@@ -938,7 +935,7 @@ impl Trait {
     }
 
     pub fn is_auto(self, db: &impl DefDatabase) -> bool {
-        self.trait_data(db).is_auto()
+        self.trait_data(db).auto
     }
 
     pub(crate) fn resolver(self, db: &impl DefDatabase) -> Resolver {
@@ -971,7 +968,7 @@ impl TypeAlias {
 
     /// The containing trait, if this is a trait method definition.
     pub fn parent_trait(self, db: &impl DefDatabase) -> Option<Trait> {
-        db.trait_items_index(self.module(db)).get_parent_trait(self.into())
+        db.trait_items_index(self.module(db).id).get_parent_trait(self.id.into()).map(Trait::from)
     }
 
     pub fn container(self, db: &impl DefDatabase) -> Option<Container> {
diff --git a/crates/ra_hir/src/code_model/src.rs b/crates/ra_hir/src/code_model/src.rs
index 556417b0f..91cab7414 100644
--- a/crates/ra_hir/src/code_model/src.rs
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -1,5 +1,6 @@
 //! FIXME: write short doc here
 
+use hir_def::{HasSource as _, Lookup};
 use ra_syntax::ast::{self, AstNode};
 
 use crate::{
@@ -113,7 +114,7 @@ impl HasSource for EnumVariant {
 impl HasSource for Function {
     type Ast = ast::FnDef;
     fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<ast::FnDef> {
-        self.id.source(db)
+        self.id.lookup(db).source(db)
     }
 }
 impl HasSource for Const {
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 0d35014a0..73859e1e9 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -11,7 +11,6 @@ use crate::{
     generics::{GenericDef, GenericParams},
     ids,
     lang_item::{LangItemTarget, LangItems},
-    traits::TraitData,
     ty::{
         method_resolution::CrateImplBlocks,
         traits::{AssocTyValue, Impl},
@@ -26,7 +25,8 @@ use crate::{
 pub use hir_def::db::{
     BodyQuery, BodyWithSourceMapQuery, CrateDefMapQuery, DefDatabase2, DefDatabase2Storage,
     EnumDataQuery, ExprScopesQuery, ImplDataQuery, InternDatabase, InternDatabaseStorage,
-    RawItemsQuery, RawItemsWithSourceMapQuery, StructDataQuery,
+    RawItemsQuery, RawItemsWithSourceMapQuery, StructDataQuery, TraitDataQuery,
+    TraitItemsIndexQuery,
 };
 pub use hir_expand::db::{
     AstDatabase, AstDatabaseStorage, AstIdMapQuery, MacroArgQuery, MacroDefQuery, MacroExpandQuery,
@@ -37,12 +37,6 @@ pub use hir_expand::db::{
 #[salsa::query_group(DefDatabaseStorage)]
 #[salsa::requires(AstDatabase)]
 pub trait DefDatabase: HirDebugDatabase + DefDatabase2 {
-    #[salsa::invoke(crate::traits::TraitData::trait_data_query)]
-    fn trait_data(&self, t: Trait) -> Arc<TraitData>;
-
-    #[salsa::invoke(crate::traits::TraitItemsIndex::trait_items_index)]
-    fn trait_items_index(&self, module: Module) -> crate::traits::TraitItemsIndex;
-
     #[salsa::invoke(crate::generics::generic_params_query)]
     fn generic_params(&self, def: GenericDef) -> Arc<GenericParams>;
 
diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
index f4dca25cb..303d5f138 100644
--- a/crates/ra_hir/src/from_source.rs
+++ b/crates/ra_hir/src/from_source.rs
@@ -4,15 +4,15 @@ use hir_def::{ModuleId, StructId, StructOrUnionId, UnionId};
 use hir_expand::{name::AsName, AstId, MacroDefId, MacroDefKind};
 use ra_syntax::{
     ast::{self, AstNode, NameOwner},
-    match_ast,
+    match_ast, AstPtr,
 };
 
 use crate::{
     db::{AstDatabase, DefDatabase, HirDatabase},
     ids::{AstItemDef, LocationCtx},
-    Const, DefWithBody, Enum, EnumVariant, FieldSource, Function, HasBody, HasSource, ImplBlock,
-    Local, MacroDef, Module, ModuleSource, Source, Static, Struct, StructField, Trait, TypeAlias,
-    Union, VariantDef,
+    AssocItem, Const, DefWithBody, Enum, EnumVariant, FieldSource, Function, HasBody, HasSource,
+    ImplBlock, Local, MacroDef, Module, ModuleDef, ModuleSource, Source, Static, Struct,
+    StructField, Trait, TypeAlias, Union, VariantDef,
 };
 
 pub trait FromSource: Sized {
@@ -52,10 +52,51 @@ impl FromSource for Trait {
 impl FromSource for Function {
     type Ast = ast::FnDef;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
-        let id = from_source(db, src)?;
-        Some(Function { id })
+        // FIXME: this doesn't try to handle nested declarations
+        for container in src.value.syntax().ancestors() {
+            let res = match_ast! {
+                match container {
+                    ast::TraitDef(it) => {
+                        let c = Trait::from_source(db, src.with_value(it))?;
+                        c.items(db)
+                            .into_iter()
+                            .filter_map(|it| match it {
+                                AssocItem::Function(it) => Some(it),
+                                _ => None
+                            })
+                            .find(|it| same_source(&it.source(db), &src))?
+                    },
+                    ast::ImplBlock(it) => {
+                        let c = ImplBlock::from_source(db, src.with_value(it))?;
+                        c.items(db)
+                            .into_iter()
+                            .filter_map(|it| match it {
+                                AssocItem::Function(it) => Some(it),
+                                _ => None
+                            })
+                            .find(|it| same_source(&it.source(db), &src))?
+
+                     },
+                    _ => { continue },
+                }
+            };
+            return Some(res);
+        }
+
+        let module_source = ModuleSource::from_child_node(db, src.as_ref().map(|it| it.syntax()));
+        let c = Module::from_definition(db, src.with_value(module_source))?;
+        let res = c
+            .declarations(db)
+            .into_iter()
+            .filter_map(|it| match it {
+                ModuleDef::Function(it) => Some(it),
+                _ => None,
+            })
+            .find(|it| same_source(&it.source(db), &src));
+        res
     }
 }
+
 impl FromSource for Const {
     type Ast = ast::ConstDef;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
@@ -108,7 +149,7 @@ impl FromSource for EnumVariant {
         let parent_enum = src.value.parent_enum();
         let src_enum = Source { file_id: src.file_id, value: parent_enum };
         let variants = Enum::from_source(db, src_enum)?.variants(db);
-        variants.into_iter().find(|v| v.source(db) == src)
+        variants.into_iter().find(|v| same_source(&v.source(db), &src))
     }
 }
 
@@ -216,3 +257,13 @@ where
     let ctx = LocationCtx::new(db, module.id, src.file_id);
     Some(DEF::from_ast(ctx, &src.value))
 }
+
+/// XXX: AST Nodes and SyntaxNodes have identity equality semantics: nodes are
+/// equal if they point to exactly the same object.
+///
+/// In general, we do not guarantee that we have exactly one instance of a
+/// syntax tree for each file. We probably should add such guanratree, but, for
+/// the time being, we will use identity-less AstPtr comparison.
+fn same_source<N: AstNode>(s1: &Source<N>, s2: &Source<N>) -> bool {
+    s1.as_ref().map(AstPtr::new) == s2.as_ref().map(AstPtr::new)
+}
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index da33c9591..7ac9a9041 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -33,7 +33,6 @@ pub mod source_binder;
 
 mod ids;
 mod adt;
-mod traits;
 mod type_alias;
 mod ty;
 mod impl_block;
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index a1c1daacd..caa8d0082 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -70,7 +70,7 @@ fn def_with_body_from_child_node(
     child.value.ancestors().find_map(|node| {
         match_ast! {
             match node {
-                ast::FnDef(def)  => { Some(Function {id: ctx.to_def(&def) }.into()) },
+                ast::FnDef(def)  => { return Function::from_source(db, child.with_value(def)).map(DefWithBody::from); },
                 ast::ConstDef(def) => { Some(Const { id: ctx.to_def(&def) }.into()) },
                 ast::StaticDef(def) => { Some(Static { id: ctx.to_def(&def) }.into()) },
                 _ => { None },
@@ -405,9 +405,16 @@ impl SourceAnalyzer {
         implements_trait(&canonical_ty, db, &self.resolver, krate, std_future_trait)
     }
 
-    pub fn expand(&self, db: &impl HirDatabase, macro_call: &ast::MacroCall) -> Option<Expansion> {
-        let def = self.resolve_macro_call(db, macro_call)?.id;
-        let ast_id = AstId::new(self.file_id, db.ast_id_map(self.file_id).ast_id(macro_call));
+    pub fn expand(
+        &self,
+        db: &impl HirDatabase,
+        macro_call: Source<&ast::MacroCall>,
+    ) -> Option<Expansion> {
+        let def = self.resolve_macro_call(db, macro_call.value)?.id;
+        let ast_id = AstId::new(
+            macro_call.file_id,
+            db.ast_id_map(macro_call.file_id).ast_id(macro_call.value),
+        );
         let macro_call_loc = MacroCallLoc { def, ast_id };
         Some(Expansion { macro_call_id: db.intern_macro(macro_call_loc) })
     }
diff --git a/crates/ra_hir/src/traits.rs b/crates/ra_hir/src/traits.rs
deleted file mode 100644
index 858972c6f..000000000
--- a/crates/ra_hir/src/traits.rs
+++ /dev/null
@@ -1,82 +0,0 @@
-//! HIR for trait definitions.
-
-use std::sync::Arc;
-
-use hir_expand::name::AsName;
-
-use ra_syntax::ast::{self, NameOwner};
-use rustc_hash::FxHashMap;
-
-use crate::{
-    db::{AstDatabase, DefDatabase},
-    ids::LocationCtx,
-    AssocItem, Const, Function, HasSource, Module, Name, Trait, TypeAlias,
-};
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct TraitData {
-    name: Option<Name>,
-    items: Vec<AssocItem>,
-    auto: bool,
-}
-
-impl TraitData {
-    pub(crate) fn trait_data_query(
-        db: &(impl DefDatabase + AstDatabase),
-        tr: Trait,
-    ) -> Arc<TraitData> {
-        let src = tr.source(db);
-        let name = src.value.name().map(|n| n.as_name());
-        let module = tr.module(db);
-        let ctx = LocationCtx::new(db, module.id, src.file_id);
-        let auto = src.value.is_auto();
-        let items = if let Some(item_list) = src.value.item_list() {
-            item_list
-                .impl_items()
-                .map(|item_node| match item_node {
-                    ast::ImplItem::FnDef(it) => Function { id: ctx.to_def(&it) }.into(),
-                    ast::ImplItem::ConstDef(it) => Const { id: ctx.to_def(&it) }.into(),
-                    ast::ImplItem::TypeAliasDef(it) => TypeAlias { id: ctx.to_def(&it) }.into(),
-                })
-                .collect()
-        } else {
-            Vec::new()
-        };
-        Arc::new(TraitData { name, items, auto })
-    }
-
-    pub(crate) fn name(&self) -> &Option<Name> {
-        &self.name
-    }
-
-    pub(crate) fn items(&self) -> &[AssocItem] {
-        &self.items
-    }
-
-    pub(crate) fn is_auto(&self) -> bool {
-        self.auto
-    }
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct TraitItemsIndex {
-    traits_by_def: FxHashMap<AssocItem, Trait>,
-}
-
-impl TraitItemsIndex {
-    pub(crate) fn trait_items_index(db: &impl DefDatabase, module: Module) -> TraitItemsIndex {
-        let mut index = TraitItemsIndex { traits_by_def: FxHashMap::default() };
-        for decl in module.declarations(db) {
-            if let crate::ModuleDef::Trait(tr) = decl {
-                for item in tr.trait_data(db).items() {
-                    index.traits_by_def.insert(*item, tr);
-                }
-            }
-        }
-        index
-    }
-
-    pub(crate) fn get_parent_trait(&self, item: AssocItem) -> Option<Trait> {
-        self.traits_by_def.get(&item).cloned()
-    }
-}
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index d20aeaacf..f377fca48 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -232,8 +232,8 @@ fn iterate_trait_method_candidates<T>(
         // 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 data.items() {
-            if !is_valid_candidate(db, name, mode, item) {
+        for &item in data.items.iter() {
+            if !is_valid_candidate(db, name, mode, item.into()) {
                 continue;
             }
             if !known_implemented {
@@ -243,7 +243,7 @@ fn iterate_trait_method_candidates<T>(
                 }
             }
             known_implemented = true;
-            if let Some(result) = callback(&ty.value, item) {
+            if let Some(result) = callback(&ty.value, item.into()) {
                 return Some(result);
             }
         }
diff --git a/crates/ra_hir_def/src/body.rs b/crates/ra_hir_def/src/body.rs
index 3804b65c7..b69d4dea6 100644
--- a/crates/ra_hir_def/src/body.rs
+++ b/crates/ra_hir_def/src/body.rs
@@ -17,7 +17,7 @@ use crate::{
     expr::{Expr, ExprId, Pat, PatId},
     nameres::CrateDefMap,
     path::Path,
-    AstItemDef, DefWithBodyId, ModuleId,
+    AstItemDef, DefWithBodyId, HasModule, HasSource, Lookup, ModuleId,
 };
 
 pub struct Expander {
@@ -149,6 +149,7 @@ impl Body {
 
         let (file_id, module, body) = match def {
             DefWithBodyId::FunctionId(f) => {
+                let f = f.lookup(db);
                 let src = f.source(db);
                 params = src.value.param_list();
                 (src.file_id, f.module(db), src.value.body().map(ast::Expr::from))
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index 348aca07f..e4ffdebe9 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -8,18 +8,19 @@ use ra_syntax::ast;
 use crate::{
     adt::{EnumData, StructData},
     body::{scope::ExprScopes, Body, BodySourceMap},
-    imp::ImplData,
+    impls::ImplData,
     nameres::{
         raw::{ImportSourceMap, RawItems},
         CrateDefMap,
     },
-    DefWithBodyId, EnumId, ImplId, ItemLoc, StructOrUnionId,
+    traits::{TraitData, TraitItemsIndex},
+    DefWithBodyId, EnumId, FunctionLoc, ImplId, ItemLoc, ModuleId, StructOrUnionId, TraitId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
 pub trait InternDatabase: SourceDatabase {
     #[salsa::interned]
-    fn intern_function(&self, loc: ItemLoc<ast::FnDef>) -> crate::FunctionId;
+    fn intern_function(&self, loc: FunctionLoc) -> crate::FunctionId;
     #[salsa::interned]
     fn intern_struct_or_union(&self, loc: ItemLoc<ast::StructDef>) -> crate::StructOrUnionId;
     #[salsa::interned]
@@ -59,6 +60,12 @@ pub trait DefDatabase2: InternDatabase + AstDatabase {
     #[salsa::invoke(ImplData::impl_data_query)]
     fn impl_data(&self, e: ImplId) -> Arc<ImplData>;
 
+    #[salsa::invoke(TraitData::trait_data_query)]
+    fn trait_data(&self, e: TraitId) -> Arc<TraitData>;
+
+    #[salsa::invoke(TraitItemsIndex::trait_items_index)]
+    fn trait_items_index(&self, module: ModuleId) -> TraitItemsIndex;
+
     #[salsa::invoke(Body::body_with_source_map_query)]
     fn body_with_source_map(&self, def: DefWithBodyId) -> (Arc<Body>, Arc<BodySourceMap>);
 
diff --git a/crates/ra_hir_def/src/generics.rs b/crates/ra_hir_def/src/generics.rs
index 4adfc16bb..11dd2a948 100644
--- a/crates/ra_hir_def/src/generics.rs
+++ b/crates/ra_hir_def/src/generics.rs
@@ -11,7 +11,7 @@ use ra_syntax::ast::{self, NameOwner, TypeBoundsOwner, TypeParamsOwner};
 use crate::{
     db::DefDatabase2,
     type_ref::{TypeBound, TypeRef},
-    AdtId, AstItemDef, GenericDefId,
+    AdtId, AstItemDef, GenericDefId, HasSource, Lookup,
 };
 
 /// Data about a generic parameter (to a function, struct, impl, ...).
@@ -53,7 +53,7 @@ impl GenericParams {
         let start = generics.parent_params.as_ref().map(|p| p.params.len()).unwrap_or(0) as u32;
         // FIXME: add `: Sized` bound for everything except for `Self` in traits
         match def {
-            GenericDefId::FunctionId(it) => generics.fill(&it.source(db).value, start),
+            GenericDefId::FunctionId(it) => generics.fill(&it.lookup(db).source(db).value, start),
             GenericDefId::AdtId(AdtId::StructId(it)) => {
                 generics.fill(&it.0.source(db).value, start)
             }
diff --git a/crates/ra_hir_def/src/imp.rs b/crates/ra_hir_def/src/impls.rs
index 4323dfcb6..9be38c5e1 100644
--- a/crates/ra_hir_def/src/imp.rs
+++ b/crates/ra_hir_def/src/impls.rs
@@ -5,11 +5,12 @@
 
 use std::sync::Arc;
 
+use hir_expand::AstId;
 use ra_syntax::ast;
 
 use crate::{
-    db::DefDatabase2, type_ref::TypeRef, AssocItemId, AstItemDef, ConstId, FunctionId, ImplId,
-    LocationCtx, TypeAliasId,
+    db::DefDatabase2, type_ref::TypeRef, AssocItemId, AstItemDef, ConstId, FunctionContainerId,
+    FunctionLoc, ImplId, Intern, LocationCtx, TypeAliasId,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -35,7 +36,12 @@ impl ImplData {
                 .impl_items()
                 .map(|item_node| match item_node {
                     ast::ImplItem::FnDef(it) => {
-                        FunctionId::from_ast_id(ctx, items.ast_id(&it)).into()
+                        let func_id = FunctionLoc {
+                            container: FunctionContainerId::ImplId(id),
+                            ast_id: AstId::new(src.file_id, items.ast_id(&it)),
+                        }
+                        .intern(db);
+                        func_id.into()
                     }
                     ast::ImplItem::ConstDef(it) => {
                         ConstId::from_ast_id(ctx, items.ast_id(&it)).into()
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index dffc82ff8..b9a13776f 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -13,11 +13,12 @@ pub mod path;
 pub mod type_ref;
 pub mod builtin_type;
 pub mod adt;
-pub mod imp;
+pub mod impls;
 pub mod diagnostics;
 pub mod expr;
 pub mod body;
 pub mod generics;
+pub mod traits;
 
 #[cfg(test)]
 mod test_db;
@@ -198,16 +199,34 @@ pub trait AstItemDef<N: AstNode>: salsa::InternKey + Clone {
 pub struct FunctionId(salsa::InternId);
 impl_intern_key!(FunctionId);
 
-impl AstItemDef<ast::FnDef> for FunctionId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::FnDef>) -> Self {
-        db.intern_function(loc)
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct FunctionLoc {
+    pub container: FunctionContainerId,
+    pub ast_id: AstId<ast::FnDef>,
+}
+
+impl Intern for FunctionLoc {
+    type ID = FunctionId;
+    fn intern(self, db: &impl db::DefDatabase2) -> FunctionId {
+        db.intern_function(self)
     }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::FnDef> {
-        db.lookup_intern_function(self)
+}
+
+impl Lookup for FunctionId {
+    type Data = FunctionLoc;
+    fn lookup(&self, db: &impl db::DefDatabase2) -> FunctionLoc {
+        db.lookup_intern_function(*self)
     }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum FunctionContainerId {
+    ModuleId(ModuleId),
+    ImplId(ImplId),
+    TraitId(TraitId),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct StructOrUnionId(salsa::InternId);
 impl_intern_key!(StructOrUnionId);
 impl AstItemDef<ast::StructDef> for StructOrUnionId {
@@ -432,3 +451,41 @@ impl_froms!(
     EnumVariantId,
     ConstId
 );
+
+trait Intern {
+    type ID;
+    fn intern(self, db: &impl db::DefDatabase2) -> Self::ID;
+}
+
+pub trait Lookup {
+    type Data;
+    fn lookup(&self, db: &impl db::DefDatabase2) -> Self::Data;
+}
+
+pub trait HasModule {
+    fn module(&self, db: &impl db::DefDatabase2) -> ModuleId;
+}
+
+impl HasModule for FunctionLoc {
+    fn module(&self, db: &impl db::DefDatabase2) -> ModuleId {
+        match self.container {
+            FunctionContainerId::ModuleId(it) => it,
+            FunctionContainerId::ImplId(it) => it.module(db),
+            FunctionContainerId::TraitId(it) => it.module(db),
+        }
+    }
+}
+
+pub trait HasSource {
+    type Value;
+    fn source(&self, db: &impl db::DefDatabase2) -> Source<Self::Value>;
+}
+
+impl HasSource for FunctionLoc {
+    type Value = ast::FnDef;
+
+    fn source(&self, db: &impl db::DefDatabase2) -> Source<ast::FnDef> {
+        let node = self.ast_id.to_node(db);
+        Source::new(self.ast_id.file_id(), node)
+    }
+}
diff --git a/crates/ra_hir_def/src/nameres.rs b/crates/ra_hir_def/src/nameres.rs
index e5b073a0f..c01e020ef 100644
--- a/crates/ra_hir_def/src/nameres.rs
+++ b/crates/ra_hir_def/src/nameres.rs
@@ -165,6 +165,14 @@ impl ModuleScope {
         self.items.iter().chain(BUILTIN_SCOPE.iter())
     }
 
+    pub fn declarations(&self) -> impl Iterator<Item = ModuleDefId> + '_ {
+        self.entries()
+            .filter_map(|(_name, res)| if res.import.is_none() { Some(res.def) } else { None })
+            .flat_map(|per_ns| {
+                per_ns.take_types().into_iter().chain(per_ns.take_values().into_iter())
+            })
+    }
+
     /// Iterate over all module scoped macros
     pub fn macros<'a>(&'a self) -> impl Iterator<Item = (&'a Name, MacroDefId)> + 'a {
         self.items
diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index 8f426b097..d2ed94a87 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -19,9 +19,9 @@ use crate::{
         per_ns::PerNs, raw, CrateDefMap, ModuleData, Resolution, ResolveMode,
     },
     path::{Path, PathKind},
-    AdtId, AstId, AstItemDef, ConstId, CrateModuleId, EnumId, EnumVariantId, FunctionId, ImplId,
-    LocationCtx, ModuleDefId, ModuleId, StaticId, StructId, StructOrUnionId, TraitId, TypeAliasId,
-    UnionId,
+    AdtId, AstId, AstItemDef, ConstId, CrateModuleId, EnumId, EnumVariantId, FunctionContainerId,
+    FunctionLoc, ImplId, Intern, LocationCtx, ModuleDefId, ModuleId, StaticId, StructId,
+    StructOrUnionId, TraitId, TypeAliasId, UnionId,
 };
 
 pub(super) fn collect_defs(db: &impl DefDatabase2, mut def_map: CrateDefMap) -> CrateDefMap {
@@ -673,7 +673,12 @@ where
         let name = def.name.clone();
         let def: PerNs = match def.kind {
             raw::DefKind::Function(ast_id) => {
-                let f = FunctionId::from_ast_id(ctx, ast_id);
+                let f = FunctionLoc {
+                    container: FunctionContainerId::ModuleId(module),
+                    ast_id: AstId::new(self.file_id, ast_id),
+                }
+                .intern(self.def_collector.db);
+
                 PerNs::values(f.into())
             }
             raw::DefKind::Struct(ast_id) => {
diff --git a/crates/ra_hir_def/src/traits.rs b/crates/ra_hir_def/src/traits.rs
new file mode 100644
index 000000000..6e36bc0d0
--- /dev/null
+++ b/crates/ra_hir_def/src/traits.rs
@@ -0,0 +1,82 @@
+//! HIR for trait definitions.
+
+use std::sync::Arc;
+
+use hir_expand::{
+    name::{AsName, Name},
+    AstId,
+};
+
+use ra_syntax::ast::{self, NameOwner};
+use rustc_hash::FxHashMap;
+
+use crate::{
+    db::DefDatabase2, AssocItemId, AstItemDef, ConstId, FunctionContainerId, FunctionLoc, Intern,
+    LocationCtx, ModuleDefId, ModuleId, TraitId, TypeAliasId,
+};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct TraitData {
+    pub name: Option<Name>,
+    pub items: Vec<AssocItemId>,
+    pub auto: bool,
+}
+
+impl TraitData {
+    pub(crate) fn trait_data_query(db: &impl DefDatabase2, tr: TraitId) -> Arc<TraitData> {
+        let src = tr.source(db);
+        let name = src.value.name().map(|n| n.as_name());
+        let module = tr.module(db);
+        let ctx = LocationCtx::new(db, module, src.file_id);
+        let auto = src.value.is_auto();
+        let ast_id_map = db.ast_id_map(src.file_id);
+        let items = if let Some(item_list) = src.value.item_list() {
+            item_list
+                .impl_items()
+                .map(|item_node| match item_node {
+                    ast::ImplItem::FnDef(it) => FunctionLoc {
+                        container: FunctionContainerId::TraitId(tr),
+                        ast_id: AstId::new(src.file_id, ast_id_map.ast_id(&it)),
+                    }
+                    .intern(db)
+                    .into(),
+                    ast::ImplItem::ConstDef(it) => ConstId::from_ast(ctx, &it).into(),
+                    ast::ImplItem::TypeAliasDef(it) => TypeAliasId::from_ast(ctx, &it).into(),
+                })
+                .collect()
+        } else {
+            Vec::new()
+        };
+        Arc::new(TraitData { name, items, auto })
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct TraitItemsIndex {
+    traits_by_def: FxHashMap<AssocItemId, TraitId>,
+}
+
+impl TraitItemsIndex {
+    pub fn trait_items_index(db: &impl DefDatabase2, module: ModuleId) -> TraitItemsIndex {
+        let mut index = TraitItemsIndex { traits_by_def: FxHashMap::default() };
+        let crate_def_map = db.crate_def_map(module.krate);
+        for decl in crate_def_map[module.module_id].scope.declarations() {
+            if let ModuleDefId::TraitId(tr) = decl {
+                for item in db.trait_data(tr).items.iter() {
+                    match item {
+                        AssocItemId::FunctionId(_) => (),
+                        _ => {
+                            let prev = index.traits_by_def.insert(*item, tr);
+                            assert!(prev.is_none());
+                        }
+                    }
+                }
+            }
+        }
+        index
+    }
+
+    pub fn get_parent_trait(&self, item: AssocItemId) -> Option<TraitId> {
+        self.traits_by_def.get(&item).cloned()
+    }
+}
diff --git a/crates/ra_ide_api/src/expand.rs b/crates/ra_ide_api/src/expand.rs
index 0ad125a9e..2f1abf509 100644
--- a/crates/ra_ide_api/src/expand.rs
+++ b/crates/ra_ide_api/src/expand.rs
@@ -55,7 +55,7 @@ pub(crate) fn descend_into_macros(
         }
         let source_analyzer =
             hir::SourceAnalyzer::new(db, token.with_value(token.value.parent()).as_ref(), None);
-        let exp = source_analyzer.expand(db, &macro_call)?;
+        let exp = source_analyzer.expand(db, token.with_value(&macro_call))?;
         exp.map_token_down(db, token.as_ref())
     })
     .last()
diff --git a/crates/ra_ide_api/src/expand_macro.rs b/crates/ra_ide_api/src/expand_macro.rs
index 2d478ec09..7f39262dc 100644
--- a/crates/ra_ide_api/src/expand_macro.rs
+++ b/crates/ra_ide_api/src/expand_macro.rs
@@ -23,7 +23,7 @@ pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<
     let mac = name_ref.syntax().ancestors().find_map(ast::MacroCall::cast)?;
 
     let source = hir::Source::new(position.file_id.into(), mac.syntax());
-    let expanded = expand_macro_recur(db, source, &mac)?;
+    let expanded = expand_macro_recur(db, source, source.with_value(&mac))?;
 
     // FIXME:
     // macro expansion may lose all white space information
@@ -35,10 +35,10 @@ pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<
 fn expand_macro_recur(
     db: &RootDatabase,
     source: hir::Source<&SyntaxNode>,
-    macro_call: &ast::MacroCall,
+    macro_call: hir::Source<&ast::MacroCall>,
 ) -> Option<SyntaxNode> {
     let analyzer = hir::SourceAnalyzer::new(db, source, None);
-    let expansion = analyzer.expand(db, &macro_call)?;
+    let expansion = analyzer.expand(db, macro_call)?;
     let macro_file_id = expansion.file_id();
     let expanded: SyntaxNode = db.parse_or_expand(macro_file_id)?;
 
@@ -46,8 +46,8 @@ fn expand_macro_recur(
     let mut replaces = FxHashMap::default();
 
     for child in children.into_iter() {
-        let source = hir::Source::new(macro_file_id, source.value);
-        let new_node = expand_macro_recur(db, source, &child)?;
+        let node = hir::Source::new(macro_file_id, &child);
+        let new_node = expand_macro_recur(db, source, node)?;
 
         replaces.insert(child.syntax().clone().into(), new_node.into());
     }
diff --git a/crates/ra_syntax/src/ptr.rs b/crates/ra_syntax/src/ptr.rs
index 31167cada..e049fce61 100644
--- a/crates/ra_syntax/src/ptr.rs
+++ b/crates/ra_syntax/src/ptr.rs
@@ -43,7 +43,7 @@ impl SyntaxNodePtr {
 }
 
 /// Like `SyntaxNodePtr`, but remembers the type of node
-#[derive(Debug, PartialEq, Eq, Hash)]
+#[derive(Debug, Hash)]
 pub struct AstPtr<N: AstNode> {
     raw: SyntaxNodePtr,
     _ty: PhantomData<fn() -> N>,
@@ -56,6 +56,14 @@ impl<N: AstNode> Clone for AstPtr<N> {
     }
 }
 
+impl<N: AstNode> Eq for AstPtr<N> {}
+
+impl<N: AstNode> PartialEq for AstPtr<N> {
+    fn eq(&self, other: &AstPtr<N>) -> bool {
+        self.raw == other.raw
+    }
+}
+
 impl<N: AstNode> AstPtr<N> {
     pub fn new(node: &N) -> AstPtr<N> {
         AstPtr { raw: SyntaxNodePtr::new(node.syntax()), _ty: PhantomData }