Merge #623

623: WIP: module id is not def id r=matklad a=matklad

This achieves two things:

* makes module_tree & item_map per crate, not per source_root
* begins the refactoring to remove universal `DefId` in favor of having separate ids for each kind of `Def`. Currently, only modules get a differnt ID though. 

Co-authored-by: Aleksey Kladov <[email protected]>

22 files changed, 808 insertions, 876 deletions

diff --git a/crates/ra_hir/src/adt.rs b/crates/ra_hir/src/adt.rs
index ab1c428db..6b13b464d 100644
--- a/crates/ra_hir/src/adt.rs
+++ b/crates/ra_hir/src/adt.rs
@@ -3,25 +3,35 @@
 
 use std::sync::Arc;
 
-use ra_syntax::{
-    SyntaxNode,
-    ast::{self, NameOwner, StructFlavor, AstNode}
-};
+use ra_syntax::ast::{self, NameOwner, StructFlavor};
 
 use crate::{
-    DefId, DefLoc, Name, AsName, Struct, Enum, EnumVariant,
-    HirDatabase, DefKind,
-    SourceItemId,
+    Name, AsName, Struct, Enum, EnumVariant, Crate,
+    HirDatabase,
     type_ref::TypeRef,
+    ids::LocationCtx,
 };
 
-impl Struct {
-    pub(crate) fn new(def_id: DefId) -> Self {
-        Struct { def_id }
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum AdtDef {
+    Struct(Struct),
+    Enum(Enum),
+}
+impl_froms!(AdtDef: Struct, Enum);
+
+impl AdtDef {
+    pub(crate) fn krate(self, db: &impl HirDatabase) -> Option<Crate> {
+        match self {
+            AdtDef::Struct(s) => s.module(db),
+            AdtDef::Enum(e) => e.module(db),
+        }
+        .krate(db)
     }
+}
 
+impl Struct {
     pub(crate) fn variant_data(&self, db: &impl HirDatabase) -> Arc<VariantData> {
-        db.struct_data(self.def_id).variant_data.clone()
+        db.struct_data((*self).into()).variant_data.clone()
     }
 }
 
@@ -39,38 +49,12 @@ impl StructData {
         StructData { name, variant_data }
     }
 
-    pub(crate) fn struct_data_query(db: &impl HirDatabase, def_id: DefId) -> Arc<StructData> {
-        let def_loc = def_id.loc(db);
-        assert!(def_loc.kind == DefKind::Struct);
-        let syntax = db.file_item(def_loc.source_item_id);
-        let struct_def =
-            ast::StructDef::cast(&syntax).expect("struct def should point to StructDef node");
-        Arc::new(StructData::new(struct_def))
+    pub(crate) fn struct_data_query(db: &impl HirDatabase, struct_: Struct) -> Arc<StructData> {
+        let (_, struct_def) = struct_.source(db);
+        Arc::new(StructData::new(&*struct_def))
     }
 }
 
-fn get_def_id(
-    db: &impl HirDatabase,
-    same_file_loc: &DefLoc,
-    node: &SyntaxNode,
-    expected_kind: DefKind,
-) -> DefId {
-    let file_id = same_file_loc.source_item_id.file_id;
-    let file_items = db.file_items(file_id);
-
-    let item_id = file_items.id_of(file_id, node);
-    let source_item_id = SourceItemId {
-        item_id: Some(item_id),
-        ..same_file_loc.source_item_id
-    };
-    let loc = DefLoc {
-        kind: expected_kind,
-        source_item_id,
-        ..*same_file_loc
-    };
-    loc.id(db)
-}
-
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct EnumData {
     pub(crate) name: Option<Name>,
@@ -83,27 +67,24 @@ impl EnumData {
         EnumData { name, variants }
     }
 
-    pub(crate) fn enum_data_query(db: &impl HirDatabase, def_id: DefId) -> Arc<EnumData> {
-        let def_loc = def_id.loc(db);
-        assert!(def_loc.kind == DefKind::Enum);
-        let syntax = db.file_item(def_loc.source_item_id);
-        let enum_def = ast::EnumDef::cast(&syntax).expect("enum def should point to EnumDef node");
+    pub(crate) fn enum_data_query(db: &impl HirDatabase, e: Enum) -> Arc<EnumData> {
+        let (file_id, enum_def) = e.source(db);
+        let module = e.module(db);
+        let ctx = LocationCtx::new(db, module, file_id);
         let variants = if let Some(vl) = enum_def.variant_list() {
             vl.variants()
                 .filter_map(|variant_def| {
-                    let name = variant_def.name().map(|n| n.as_name());
-
-                    name.map(|n| {
-                        let def_id =
-                            get_def_id(db, &def_loc, variant_def.syntax(), DefKind::EnumVariant);
-                        (n, EnumVariant::new(def_id))
-                    })
+                    let name = variant_def.name()?.as_name();
+                    let var = EnumVariant {
+                        id: ctx.to_def(variant_def),
+                    };
+                    Some((name, var))
                 })
                 .collect()
         } else {
             Vec::new()
         };
-        Arc::new(EnumData::new(enum_def, variants))
+        Arc::new(EnumData::new(&*enum_def, variants))
     }
 }
 
@@ -128,21 +109,15 @@ impl EnumVariantData {
 
     pub(crate) fn enum_variant_data_query(
         db: &impl HirDatabase,
-        def_id: DefId,
+        var: EnumVariant,
     ) -> Arc<EnumVariantData> {
-        let def_loc = def_id.loc(db);
-        assert!(def_loc.kind == DefKind::EnumVariant);
-        let syntax = db.file_item(def_loc.source_item_id);
-        let variant_def = ast::EnumVariant::cast(&syntax)
-            .expect("enum variant def should point to EnumVariant node");
-        let enum_node = syntax
-            .parent()
-            .expect("enum variant should have enum variant list ancestor")
-            .parent()
-            .expect("enum variant list should have enum ancestor");
-        let enum_def_id = get_def_id(db, &def_loc, enum_node, DefKind::Enum);
-
-        Arc::new(EnumVariantData::new(variant_def, Enum::new(enum_def_id)))
+        let (file_id, variant_def) = var.source(db);
+        let enum_def = variant_def.parent_enum();
+        let ctx = LocationCtx::new(db, var.module(db), file_id);
+        let e = Enum {
+            id: ctx.to_def(enum_def),
+        };
+        Arc::new(EnumVariantData::new(&*variant_def, e))
     }
 }
 
diff --git a/crates/ra_hir/src/code_model_api.rs b/crates/ra_hir/src/code_model_api.rs
index 3ff07bd60..6739627b4 100644
--- a/crates/ra_hir/src/code_model_api.rs
+++ b/crates/ra_hir/src/code_model_api.rs
@@ -5,22 +5,23 @@ use ra_db::{CrateId, FileId};
 use ra_syntax::{ast::self, TreeArc, SyntaxNode};
 
 use crate::{
-    Name, DefId, Path, PerNs, ScopesWithSyntaxMapping, Ty, HirFileId,
+    Name, Path, PerNs, ScopesWithSyntaxMapping, Ty, HirFileId,
     type_ref::TypeRef,
     nameres::{ModuleScope, lower::ImportId},
     db::HirDatabase,
     expr::BodySyntaxMapping,
-    ty::InferenceResult,
+    ty::{InferenceResult, VariantDef},
     adt::VariantData,
     generics::GenericParams,
-    code_model_impl::def_id_to_ast,
-    docs::{Documentation, Docs, docs_from_ast}
+    docs::{Documentation, Docs, docs_from_ast},
+    module_tree::ModuleId,
+    ids::{FunctionId, StructId, EnumId, EnumVariantId, AstItemDef, ConstId, StaticId, TraitId, TypeId},
 };
 
 /// hir::Crate describes a single crate. It's the main interface with which
 /// a crate's dependencies interact. Mostly, it should be just a proxy for the
 /// root module.
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Crate {
     pub(crate) crate_id: CrateId,
 }
@@ -45,22 +46,40 @@ impl Crate {
 
 #[derive(Debug)]
 pub enum Def {
+    Item,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Module {
+    pub(crate) krate: CrateId,
+    pub(crate) module_id: ModuleId,
+}
+
+/// The defs which can be visible in the module.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ModuleDef {
     Module(Module),
+    Function(Function),
     Struct(Struct),
     Enum(Enum),
+    // Can't be directly declared, but can be imported.
     EnumVariant(EnumVariant),
-    Function(Function),
     Const(Const),
     Static(Static),
     Trait(Trait),
     Type(Type),
-    Item,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct Module {
-    pub(crate) def_id: DefId,
 }
+impl_froms!(
+    ModuleDef: Module,
+    Function,
+    Struct,
+    Enum,
+    EnumVariant,
+    Const,
+    Static,
+    Trait,
+    Type
+);
 
 pub enum ModuleSource {
     SourceFile(TreeArc<ast::SourceFile>),
@@ -149,7 +168,7 @@ impl Module {
         self.scope_impl(db)
     }
 
-    pub fn resolve_path(&self, db: &impl HirDatabase, path: &Path) -> PerNs<DefId> {
+    pub fn resolve_path(&self, db: &impl HirDatabase, path: &Path) -> PerNs<ModuleDef> {
         self.resolve_path_impl(db, path)
     }
 
@@ -160,7 +179,7 @@ impl Module {
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct StructField {
-    parent: DefId,
+    parent: VariantDef,
     name: Name,
 }
 
@@ -174,38 +193,38 @@ impl StructField {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Struct {
-    pub(crate) def_id: DefId,
+    pub(crate) id: StructId,
 }
 
 impl Struct {
-    pub fn def_id(&self) -> DefId {
-        self.def_id
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::StructDef>) {
+        self.id.source(db)
+    }
+
+    pub fn module(&self, db: &impl HirDatabase) -> Module {
+        self.id.module(db)
     }
 
     pub fn name(&self, db: &impl HirDatabase) -> Option<Name> {
-        db.struct_data(self.def_id).name.clone()
+        db.struct_data(*self).name.clone()
     }
 
     pub fn fields(&self, db: &impl HirDatabase) -> Vec<StructField> {
-        db.struct_data(self.def_id)
+        db.struct_data(*self)
             .variant_data
             .fields()
             .iter()
             .map(|it| StructField {
-                parent: self.def_id,
+                parent: (*self).into(),
                 name: it.name.clone(),
             })
             .collect()
     }
 
-    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::StructDef>) {
-        def_id_to_ast(db, self.def_id)
-    }
-
     pub fn generic_params(&self, db: &impl HirDatabase) -> Arc<GenericParams> {
-        db.generic_params(self.def_id)
+        db.generic_params((*self).into())
     }
 }
 
@@ -215,34 +234,30 @@ impl Docs for Struct {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Enum {
-    pub(crate) def_id: DefId,
+    pub(crate) id: EnumId,
 }
 
 impl Enum {
-    pub(crate) fn new(def_id: DefId) -> Self {
-        Enum { def_id }
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::EnumDef>) {
+        self.id.source(db)
     }
 
-    pub fn def_id(&self) -> DefId {
-        self.def_id
+    pub fn module(&self, db: &impl HirDatabase) -> Module {
+        self.id.module(db)
     }
 
     pub fn name(&self, db: &impl HirDatabase) -> Option<Name> {
-        db.enum_data(self.def_id).name.clone()
+        db.enum_data(*self).name.clone()
     }
 
     pub fn variants(&self, db: &impl HirDatabase) -> Vec<(Name, EnumVariant)> {
-        db.enum_data(self.def_id).variants.clone()
-    }
-
-    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::EnumDef>) {
-        def_id_to_ast(db, self.def_id)
+        db.enum_data(*self).variants.clone()
     }
 
     pub fn generic_params(&self, db: &impl HirDatabase) -> Arc<GenericParams> {
-        db.generic_params(self.def_id)
+        db.generic_params((*self).into())
     }
 }
 
@@ -252,30 +267,28 @@ impl Docs for Enum {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct EnumVariant {
-    pub(crate) def_id: DefId,
+    pub(crate) id: EnumVariantId,
 }
 
 impl EnumVariant {
-    pub(crate) fn new(def_id: DefId) -> Self {
-        EnumVariant { def_id }
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::EnumVariant>) {
+        self.id.source(db)
     }
-
-    pub fn def_id(&self) -> DefId {
-        self.def_id
+    pub fn module(&self, db: &impl HirDatabase) -> Module {
+        self.id.module(db)
     }
-
     pub fn parent_enum(&self, db: &impl HirDatabase) -> Enum {
-        db.enum_variant_data(self.def_id).parent_enum.clone()
+        db.enum_variant_data(*self).parent_enum.clone()
     }
 
     pub fn name(&self, db: &impl HirDatabase) -> Option<Name> {
-        db.enum_variant_data(self.def_id).name.clone()
+        db.enum_variant_data(*self).name.clone()
     }
 
     pub fn variant_data(&self, db: &impl HirDatabase) -> Arc<VariantData> {
-        db.enum_variant_data(self.def_id).variant_data.clone()
+        db.enum_variant_data(*self).variant_data.clone()
     }
 
     pub fn fields(&self, db: &impl HirDatabase) -> Vec<StructField> {
@@ -283,15 +296,11 @@ impl EnumVariant {
             .fields()
             .iter()
             .map(|it| StructField {
-                parent: self.def_id,
+                parent: (*self).into(),
                 name: it.name.clone(),
             })
             .collect()
     }
-
-    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::EnumVariant>) {
-        def_id_to_ast(db, self.def_id)
-    }
 }
 
 impl Docs for EnumVariant {
@@ -300,9 +309,9 @@ impl Docs for EnumVariant {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Function {
-    pub(crate) def_id: DefId,
+    pub(crate) id: FunctionId,
 }
 
 pub use crate::code_model_impl::function::ScopeEntryWithSyntax;
@@ -339,21 +348,21 @@ impl FnSignature {
 }
 
 impl Function {
-    pub fn def_id(&self) -> DefId {
-        self.def_id
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::FnDef>) {
+        self.id.source(db)
     }
 
-    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::FnDef>) {
-        def_id_to_ast(db, self.def_id)
+    pub fn module(&self, db: &impl HirDatabase) -> Module {
+        self.id.module(db)
     }
 
     pub fn body_syntax_mapping(&self, db: &impl HirDatabase) -> Arc<BodySyntaxMapping> {
-        db.body_syntax_mapping(self.def_id)
+        db.body_syntax_mapping(*self)
     }
 
     pub fn scopes(&self, db: &impl HirDatabase) -> ScopesWithSyntaxMapping {
-        let scopes = db.fn_scopes(self.def_id);
-        let syntax_mapping = db.body_syntax_mapping(self.def_id);
+        let scopes = db.fn_scopes(*self);
+        let syntax_mapping = db.body_syntax_mapping(*self);
         ScopesWithSyntaxMapping {
             scopes,
             syntax_mapping,
@@ -361,15 +370,15 @@ impl Function {
     }
 
     pub fn signature(&self, db: &impl HirDatabase) -> Arc<FnSignature> {
-        db.fn_signature(self.def_id)
+        db.fn_signature(*self)
     }
 
     pub fn infer(&self, db: &impl HirDatabase) -> Arc<InferenceResult> {
-        db.infer(self.def_id)
+        db.infer(*self)
     }
 
     pub fn generic_params(&self, db: &impl HirDatabase) -> Arc<GenericParams> {
-        db.generic_params(self.def_id)
+        db.generic_params((*self).into())
     }
 }
 
@@ -379,18 +388,14 @@ impl Docs for Function {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Const {
-    pub(crate) def_id: DefId,
+    pub(crate) id: ConstId,
 }
 
 impl Const {
-    pub(crate) fn new(def_id: DefId) -> Const {
-        Const { def_id }
-    }
-
     pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::ConstDef>) {
-        def_id_to_ast(db, self.def_id)
+        self.id.source(db)
     }
 }
 
@@ -400,18 +405,14 @@ impl Docs for Const {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Static {
-    pub(crate) def_id: DefId,
+    pub(crate) id: StaticId,
 }
 
 impl Static {
-    pub(crate) fn new(def_id: DefId) -> Static {
-        Static { def_id }
-    }
-
     pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::StaticDef>) {
-        def_id_to_ast(db, self.def_id)
+        self.id.source(db)
     }
 }
 
@@ -421,22 +422,18 @@ impl Docs for Static {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Trait {
-    pub(crate) def_id: DefId,
+    pub(crate) id: TraitId,
 }
 
 impl Trait {
-    pub(crate) fn new(def_id: DefId) -> Trait {
-        Trait { def_id }
-    }
-
     pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::TraitDef>) {
-        def_id_to_ast(db, self.def_id)
+        self.id.source(db)
     }
 
     pub fn generic_params(&self, db: &impl HirDatabase) -> Arc<GenericParams> {
-        db.generic_params(self.def_id)
+        db.generic_params((*self).into())
     }
 }
 
@@ -446,22 +443,18 @@ impl Docs for Trait {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Type {
-    pub(crate) def_id: DefId,
+    pub(crate) id: TypeId,
 }
 
 impl Type {
-    pub(crate) fn new(def_id: DefId) -> Type {
-        Type { def_id }
-    }
-
     pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::TypeDef>) {
-        def_id_to_ast(db, self.def_id)
+        self.id.source(db)
     }
 
     pub fn generic_params(&self, db: &impl HirDatabase) -> Arc<GenericParams> {
-        db.generic_params(self.def_id)
+        db.generic_params((*self).into())
     }
 }
 
diff --git a/crates/ra_hir/src/code_model_impl.rs b/crates/ra_hir/src/code_model_impl.rs
index 0cea9f7b6..1f28fab74 100644
--- a/crates/ra_hir/src/code_model_impl.rs
+++ b/crates/ra_hir/src/code_model_impl.rs
@@ -1,18 +1,3 @@
 mod krate; // `crate` is invalid ident :(
 mod module;
 pub(crate) mod function;
-
-use ra_syntax::{AstNode, TreeArc};
-
-use crate::{HirDatabase, DefId, HirFileId};
-
-pub(crate) fn def_id_to_ast<N: AstNode>(
-    db: &impl HirDatabase,
-    def_id: DefId,
-) -> (HirFileId, TreeArc<N>) {
-    let (file_id, syntax) = def_id.source(db);
-    let ast = N::cast(&syntax)
-        .unwrap_or_else(|| panic!("def points to wrong source {:?} {:?}", def_id, syntax))
-        .to_owned();
-    (file_id, ast)
-}
diff --git a/crates/ra_hir/src/code_model_impl/function.rs b/crates/ra_hir/src/code_model_impl/function.rs
index c68c6bfbf..e0dd4d629 100644
--- a/crates/ra_hir/src/code_model_impl/function.rs
+++ b/crates/ra_hir/src/code_model_impl/function.rs
@@ -2,41 +2,32 @@ mod scope;
 
 use std::sync::Arc;
 
-use ra_syntax::{TreeArc, ast::{self, NameOwner}};
+use ra_syntax::ast::{self, NameOwner};
 
 use crate::{
-    DefId, HirDatabase, Name, AsName, Function, FnSignature, Module,
+    HirDatabase, Name, AsName, Function, FnSignature,
     type_ref::{TypeRef, Mutability},
     expr::Body,
     impl_block::ImplBlock,
-    code_model_impl::def_id_to_ast,
 };
 
 pub use self::scope::{FnScopes, ScopesWithSyntaxMapping, ScopeEntryWithSyntax};
 
 impl Function {
-    pub(crate) fn new(def_id: DefId) -> Function {
-        Function { def_id }
-    }
-
     pub(crate) fn body(&self, db: &impl HirDatabase) -> Arc<Body> {
-        db.body_hir(self.def_id)
-    }
-
-    pub(crate) fn module(&self, db: &impl HirDatabase) -> Module {
-        self.def_id.module(db)
+        db.body_hir(*self)
     }
 
     /// The containing impl block, if this is a method.
     pub(crate) fn impl_block(&self, db: &impl HirDatabase) -> Option<ImplBlock> {
-        self.def_id.impl_block(db)
+        let module_impls = db.impls_in_module(self.module(db));
+        ImplBlock::containing(module_impls, (*self).into())
     }
 }
 
 impl FnSignature {
-    pub(crate) fn fn_signature_query(db: &impl HirDatabase, def_id: DefId) -> Arc<FnSignature> {
-        // FIXME: we're using def_id_to_ast here to avoid returning Cancelable... this is a bit hacky
-        let node: TreeArc<ast::FnDef> = def_id_to_ast(db, def_id).1;
+    pub(crate) fn fn_signature_query(db: &impl HirDatabase, func: Function) -> Arc<FnSignature> {
+        let (_, node) = func.source(db);
         let name = node
             .name()
             .map(|n| n.as_name())
diff --git a/crates/ra_hir/src/code_model_impl/krate.rs b/crates/ra_hir/src/code_model_impl/krate.rs
index 8c6e34873..cdd30b402 100644
--- a/crates/ra_hir/src/code_model_impl/krate.rs
+++ b/crates/ra_hir/src/code_model_impl/krate.rs
@@ -1,7 +1,7 @@
 use ra_db::CrateId;
 
 use crate::{
-    HirFileId, Crate, CrateDependency, AsName, DefLoc, DefKind, Module, SourceItemId,
+    Crate, CrateDependency, AsName, Module,
     db::HirDatabase,
 };
 
@@ -21,27 +21,13 @@ impl Crate {
             .collect()
     }
     pub(crate) fn root_module_impl(&self, db: &impl HirDatabase) -> Option<Module> {
-        let crate_graph = db.crate_graph();
-        let file_id = crate_graph.crate_root(self.crate_id);
-        let source_root_id = db.file_source_root(file_id);
-        let file_id = HirFileId::from(file_id);
-        let module_tree = db.module_tree(source_root_id);
-        // FIXME: teach module tree about crate roots instead of guessing
-        let source = SourceItemId {
-            file_id,
-            item_id: None,
-        };
-        let module_id = module_tree.find_module_by_source(source)?;
+        let module_tree = db.module_tree(self.crate_id);
+        let module_id = module_tree.modules().next()?;
 
-        let def_loc = DefLoc {
-            kind: DefKind::Module,
-            source_root_id,
+        let module = Module {
+            krate: self.crate_id,
             module_id,
-            source_item_id: module_id.source(&module_tree),
         };
-        let def_id = def_loc.id(db);
-
-        let module = Module::new(def_id);
         Some(module)
     }
 }
diff --git a/crates/ra_hir/src/code_model_impl/module.rs b/crates/ra_hir/src/code_model_impl/module.rs
index d94079f11..6419d3934 100644
--- a/crates/ra_hir/src/code_model_impl/module.rs
+++ b/crates/ra_hir/src/code_model_impl/module.rs
@@ -1,52 +1,33 @@
-use ra_db::{SourceRootId, FileId};
-use ra_syntax::{ast, SyntaxNode, AstNode, TreeArc};
+use ra_db::FileId;
+use ra_syntax::{ast, SyntaxNode, TreeArc};
 
 use crate::{
-    Module, ModuleSource, Problem,
-    Crate, DefId, DefLoc, DefKind, Name, Path, PathKind, PerNs, Def,
+    Module, ModuleSource, Problem, ModuleDef,
+    Crate, Name, Path, PathKind, PerNs,
     module_tree::ModuleId,
     nameres::{ModuleScope, lower::ImportId},
     db::HirDatabase,
 };
 
 impl Module {
-    pub(crate) fn new(def_id: DefId) -> Self {
-        crate::code_model_api::Module { def_id }
-    }
-
-    pub(crate) fn from_module_id(
-        db: &impl HirDatabase,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
-    ) -> Self {
-        let module_tree = db.module_tree(source_root_id);
-        let def_loc = DefLoc {
-            kind: DefKind::Module,
-            source_root_id,
+    fn with_module_id(&self, module_id: ModuleId) -> Module {
+        Module {
             module_id,
-            source_item_id: module_id.source(&module_tree),
-        };
-        let def_id = def_loc.id(db);
-        Module::new(def_id)
+            krate: self.krate,
+        }
     }
 
     pub(crate) fn name_impl(&self, db: &impl HirDatabase) -> Option<Name> {
-        let loc = self.def_id.loc(db);
-        let module_tree = db.module_tree(loc.source_root_id);
-        let link = loc.module_id.parent_link(&module_tree)?;
+        let module_tree = db.module_tree(self.krate);
+        let link = self.module_id.parent_link(&module_tree)?;
         Some(link.name(&module_tree).clone())
     }
 
     pub(crate) fn definition_source_impl(&self, db: &impl HirDatabase) -> (FileId, ModuleSource) {
-        let loc = self.def_id.loc(db);
-        let file_id = loc.source_item_id.file_id.as_original_file();
-        let syntax_node = db.file_item(loc.source_item_id);
-        let module_source = if let Some(source_file) = ast::SourceFile::cast(&syntax_node) {
-            ModuleSource::SourceFile(source_file.to_owned())
-        } else {
-            let module = ast::Module::cast(&syntax_node).unwrap();
-            ModuleSource::Module(module.to_owned())
-        };
+        let module_tree = db.module_tree(self.krate);
+        let source = self.module_id.source(&module_tree);
+        let module_source = ModuleSource::from_source_item_id(db, source);
+        let file_id = source.file_id.as_original_file();
         (file_id, module_source)
     }
 
@@ -54,9 +35,8 @@ impl Module {
         &self,
         db: &impl HirDatabase,
     ) -> Option<(FileId, TreeArc<ast::Module>)> {
-        let loc = self.def_id.loc(db);
-        let module_tree = db.module_tree(loc.source_root_id);
-        let link = loc.module_id.parent_link(&module_tree)?;
+        let module_tree = db.module_tree(self.krate);
+        let link = self.module_id.parent_link(&module_tree)?;
         let file_id = link
             .owner(&module_tree)
             .source(&module_tree)
@@ -71,85 +51,67 @@ impl Module {
         db: &impl HirDatabase,
         import: ImportId,
     ) -> TreeArc<ast::PathSegment> {
-        let loc = self.def_id.loc(db);
-        let source_map = db.lower_module_source_map(loc.source_root_id, loc.module_id);
+        let source_map = db.lower_module_source_map(self.clone());
         let (_, source) = self.definition_source(db);
         source_map.get(&source, import)
     }
 
-    pub(crate) fn krate_impl(&self, db: &impl HirDatabase) -> Option<Crate> {
-        let root = self.crate_root(db);
-        let loc = root.def_id.loc(db);
-        let file_id = loc.source_item_id.file_id.as_original_file();
-
-        let crate_graph = db.crate_graph();
-        let crate_id = crate_graph.crate_id_for_crate_root(file_id)?;
-        Some(Crate::new(crate_id))
+    pub(crate) fn krate_impl(&self, _db: &impl HirDatabase) -> Option<Crate> {
+        Some(Crate::new(self.krate))
     }
 
     pub(crate) fn crate_root_impl(&self, db: &impl HirDatabase) -> Module {
-        let loc = self.def_id.loc(db);
-        let module_tree = db.module_tree(loc.source_root_id);
-        let module_id = loc.module_id.crate_root(&module_tree);
-        Module::from_module_id(db, loc.source_root_id, module_id)
+        let module_tree = db.module_tree(self.krate);
+        let module_id = self.module_id.crate_root(&module_tree);
+        self.with_module_id(module_id)
     }
 
     /// Finds a child module with the specified name.
     pub(crate) fn child_impl(&self, db: &impl HirDatabase, name: &Name) -> Option<Module> {
-        let loc = self.def_id.loc(db);
-        let module_tree = db.module_tree(loc.source_root_id);
-        let child_id = loc.module_id.child(&module_tree, name)?;
-        Some(Module::from_module_id(db, loc.source_root_id, child_id))
+        let module_tree = db.module_tree(self.krate);
+        let child_id = self.module_id.child(&module_tree, name)?;
+        Some(self.with_module_id(child_id))
     }
 
     /// Iterates over all child modules.
     pub(crate) fn children_impl(&self, db: &impl HirDatabase) -> impl Iterator<Item = Module> {
-        // FIXME this should be implementable without collecting into a vec, but
-        // it's kind of hard since the iterator needs to keep a reference to the
-        // module tree.
-        let loc = self.def_id.loc(db);
-        let module_tree = db.module_tree(loc.source_root_id);
-        let children = loc
+        let module_tree = db.module_tree(self.krate);
+        let children = self
             .module_id
             .children(&module_tree)
-            .map(|(_, module_id)| Module::from_module_id(db, loc.source_root_id, module_id))
+            .map(|(_, module_id)| self.with_module_id(module_id))
             .collect::<Vec<_>>();
         children.into_iter()
     }
 
     pub(crate) fn parent_impl(&self, db: &impl HirDatabase) -> Option<Module> {
-        let loc = self.def_id.loc(db);
-        let module_tree = db.module_tree(loc.source_root_id);
-        let parent_id = loc.module_id.parent(&module_tree)?;
-        Some(Module::from_module_id(db, loc.source_root_id, parent_id))
+        let module_tree = db.module_tree(self.krate);
+        let parent_id = self.module_id.parent(&module_tree)?;
+        Some(self.with_module_id(parent_id))
     }
 
     /// Returns a `ModuleScope`: a set of items, visible in this module.
     pub(crate) fn scope_impl(&self, db: &impl HirDatabase) -> ModuleScope {
-        let loc = self.def_id.loc(db);
-        let item_map = db.item_map(loc.source_root_id);
-        item_map.per_module[&loc.module_id].clone()
+        let item_map = db.item_map(self.krate);
+        item_map.per_module[&self.module_id].clone()
     }
 
-    pub(crate) fn resolve_path_impl(&self, db: &impl HirDatabase, path: &Path) -> PerNs<DefId> {
-        let mut curr_per_ns = PerNs::types(
-            match path.kind {
-                PathKind::Crate => self.crate_root(db),
-                PathKind::Self_ | PathKind::Plain => self.clone(),
-                PathKind::Super => {
-                    if let Some(p) = self.parent(db) {
-                        p
-                    } else {
-                        return PerNs::none();
-                    }
-                }
-                PathKind::Abs => {
-                    // TODO: absolute use is not supported
+    pub(crate) fn resolve_path_impl(&self, db: &impl HirDatabase, path: &Path) -> PerNs<ModuleDef> {
+        let mut curr_per_ns: PerNs<ModuleDef> = PerNs::types(match path.kind {
+            PathKind::Crate => self.crate_root(db).into(),
+            PathKind::Self_ | PathKind::Plain => self.clone().into(),
+            PathKind::Super => {
+                if let Some(p) = self.parent(db) {
+                    p.into()
+                } else {
                     return PerNs::none();
                 }
             }
-            .def_id,
-        );
+            PathKind::Abs => {
+                // TODO: absolute use is not supported
+                return PerNs::none();
+            }
+        });
 
         for segment in path.segments.iter() {
             let curr = match curr_per_ns.as_ref().take_types() {
@@ -164,15 +126,16 @@ impl Module {
                 }
             };
             // resolve segment in curr
-            curr_per_ns = match curr.resolve(db) {
-                Def::Module(m) => {
+
+            curr_per_ns = match curr {
+                ModuleDef::Module(m) => {
                     let scope = m.scope(db);
                     match scope.get(&segment.name) {
-                        Some(r) => r.def_id,
+                        Some(r) => r.def_id.clone(),
                         None => PerNs::none(),
                     }
                 }
-                Def::Enum(e) => {
+                ModuleDef::Enum(e) => {
                     // enum variant
                     let matching_variant = e
                         .variants(db)
@@ -180,7 +143,7 @@ impl Module {
                         .find(|(n, _variant)| n == &segment.name);
 
                     match matching_variant {
-                        Some((_n, variant)) => PerNs::both(variant.def_id(), e.def_id()),
+                        Some((_n, variant)) => PerNs::both(variant.into(), (*e).into()),
                         None => PerNs::none(),
                     }
                 }
@@ -199,8 +162,7 @@ impl Module {
         &self,
         db: &impl HirDatabase,
     ) -> Vec<(TreeArc<SyntaxNode>, Problem)> {
-        let loc = self.def_id.loc(db);
-        let module_tree = db.module_tree(loc.source_root_id);
-        loc.module_id.problems(&module_tree, db)
+        let module_tree = db.module_tree(self.krate);
+        self.module_id.problems(&module_tree, db)
     }
 }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index cc03da1e2..5304f5d31 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,20 +1,21 @@
 use std::sync::Arc;
 
 use ra_syntax::{SyntaxNode, TreeArc, SourceFile};
-use ra_db::{SourceRootId, SyntaxDatabase, salsa};
+use ra_db::{SyntaxDatabase, CrateId, salsa};
 
 use crate::{
-    HirInterner, DefId, MacroCallId, Name, HirFileId,
-    SourceFileItems, SourceItemId, Crate,
+    MacroCallId, Name, HirFileId,
+    SourceFileItems, SourceItemId, Crate, Module, HirInterner,
     query_definitions,
-    FnSignature, FnScopes,
+    Function, FnSignature, FnScopes,
+    Struct, Enum, EnumVariant,
     macros::MacroExpansion,
-    module_tree::{ModuleId, ModuleTree},
+    module_tree::ModuleTree,
     nameres::{ItemMap, lower::{LoweredModule, ImportSourceMap}},
-    ty::{InferenceResult, Ty, method_resolution::CrateImplBlocks},
+    ty::{InferenceResult, Ty, method_resolution::CrateImplBlocks, TypableDef, VariantDef},
     adt::{StructData, EnumData, EnumVariantData},
     impl_block::ModuleImplBlocks,
-    generics::GenericParams,
+    generics::{GenericParams, GenericDef},
 };
 
 #[salsa::query_group]
@@ -26,25 +27,25 @@ pub trait HirDatabase: SyntaxDatabase + AsRef<HirInterner> {
     fn expand_macro_invocation(&self, invoc: MacroCallId) -> Option<Arc<MacroExpansion>>;
 
     #[salsa::invoke(query_definitions::fn_scopes)]
-    fn fn_scopes(&self, def_id: DefId) -> Arc<FnScopes>;
+    fn fn_scopes(&self, func: Function) -> Arc<FnScopes>;
 
     #[salsa::invoke(crate::adt::StructData::struct_data_query)]
-    fn struct_data(&self, def_id: DefId) -> Arc<StructData>;
+    fn struct_data(&self, s: Struct) -> Arc<StructData>;
 
     #[salsa::invoke(crate::adt::EnumData::enum_data_query)]
-    fn enum_data(&self, def_id: DefId) -> Arc<EnumData>;
+    fn enum_data(&self, e: Enum) -> Arc<EnumData>;
 
     #[salsa::invoke(crate::adt::EnumVariantData::enum_variant_data_query)]
-    fn enum_variant_data(&self, def_id: DefId) -> Arc<EnumVariantData>;
+    fn enum_variant_data(&self, var: EnumVariant) -> Arc<EnumVariantData>;
 
     #[salsa::invoke(crate::ty::infer)]
-    fn infer(&self, def_id: DefId) -> Arc<InferenceResult>;
+    fn infer(&self, func: Function) -> Arc<InferenceResult>;
 
     #[salsa::invoke(crate::ty::type_for_def)]
-    fn type_for_def(&self, def_id: DefId) -> Ty;
+    fn type_for_def(&self, def: TypableDef) -> Ty;
 
     #[salsa::invoke(crate::ty::type_for_field)]
-    fn type_for_field(&self, def_id: DefId, field: Name) -> Option<Ty>;
+    fn type_for_field(&self, def: VariantDef, field: Name) -> Option<Ty>;
 
     #[salsa::invoke(query_definitions::file_items)]
     fn file_items(&self, file_id: HirFileId) -> Arc<SourceFileItems>;
@@ -56,51 +57,35 @@ pub trait HirDatabase: SyntaxDatabase + AsRef<HirInterner> {
     fn submodules(&self, source: SourceItemId) -> Arc<Vec<crate::module_tree::Submodule>>;
 
     #[salsa::invoke(crate::nameres::lower::LoweredModule::lower_module_query)]
-    fn lower_module(
-        &self,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
-    ) -> (Arc<LoweredModule>, Arc<ImportSourceMap>);
+    fn lower_module(&self, module: Module) -> (Arc<LoweredModule>, Arc<ImportSourceMap>);
 
     #[salsa::invoke(crate::nameres::lower::LoweredModule::lower_module_module_query)]
-    fn lower_module_module(
-        &self,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
-    ) -> Arc<LoweredModule>;
+    fn lower_module_module(&self, module: Module) -> Arc<LoweredModule>;
 
     #[salsa::invoke(crate::nameres::lower::LoweredModule::lower_module_source_map_query)]
-    fn lower_module_source_map(
-        &self,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
-    ) -> Arc<ImportSourceMap>;
+    fn lower_module_source_map(&self, module: Module) -> Arc<ImportSourceMap>;
 
     #[salsa::invoke(query_definitions::item_map)]
-    fn item_map(&self, source_root_id: SourceRootId) -> Arc<ItemMap>;
+    fn item_map(&self, crate_id: CrateId) -> Arc<ItemMap>;
 
     #[salsa::invoke(crate::module_tree::ModuleTree::module_tree_query)]
-    fn module_tree(&self, source_root_id: SourceRootId) -> Arc<ModuleTree>;
+    fn module_tree(&self, crate_id: CrateId) -> Arc<ModuleTree>;
 
     #[salsa::invoke(crate::impl_block::impls_in_module)]
-    fn impls_in_module(
-        &self,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
-    ) -> Arc<ModuleImplBlocks>;
+    fn impls_in_module(&self, module: Module) -> Arc<ModuleImplBlocks>;
 
     #[salsa::invoke(crate::ty::method_resolution::CrateImplBlocks::impls_in_crate_query)]
     fn impls_in_crate(&self, krate: Crate) -> Arc<CrateImplBlocks>;
 
     #[salsa::invoke(crate::expr::body_hir)]
-    fn body_hir(&self, def_id: DefId) -> Arc<crate::expr::Body>;
+    fn body_hir(&self, func: Function) -> Arc<crate::expr::Body>;
 
     #[salsa::invoke(crate::expr::body_syntax_mapping)]
-    fn body_syntax_mapping(&self, def_id: DefId) -> Arc<crate::expr::BodySyntaxMapping>;
+    fn body_syntax_mapping(&self, func: Function) -> Arc<crate::expr::BodySyntaxMapping>;
 
     #[salsa::invoke(crate::generics::GenericParams::generic_params_query)]
-    fn generic_params(&self, def_id: DefId) -> Arc<GenericParams>;
+    fn generic_params(&self, def: GenericDef) -> Arc<GenericParams>;
 
     #[salsa::invoke(crate::FnSignature::fn_signature_query)]
-    fn fn_signature(&self, def_id: DefId) -> Arc<FnSignature>;
+    fn fn_signature(&self, func: Function) -> Arc<FnSignature>;
 }
diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index 1a3821692..29469af2c 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -9,7 +9,11 @@ use ra_syntax::{
     ast::{self, LoopBodyOwner, ArgListOwner, NameOwner, LiteralFlavor}
 };
 
-use crate::{Path, type_ref::{Mutability, TypeRef}, Name, HirDatabase, DefId, Def, name::AsName};
+use crate::{
+    Path, Name, HirDatabase, Function,
+    name::AsName,
+    type_ref::{Mutability, TypeRef},
+};
 use crate::ty::primitive::{UintTy, UncertainIntTy, UncertainFloatTy};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -435,8 +439,8 @@ impl Pat {
 
 // Queries
 
-pub(crate) fn body_hir(db: &impl HirDatabase, def_id: DefId) -> Arc<Body> {
-    Arc::clone(&body_syntax_mapping(db, def_id).body)
+pub(crate) fn body_hir(db: &impl HirDatabase, func: Function) -> Arc<Body> {
+    Arc::clone(&body_syntax_mapping(db, func).body)
 }
 
 struct ExprCollector {
@@ -955,14 +959,8 @@ pub(crate) fn collect_fn_body_syntax(node: &ast::FnDef) -> BodySyntaxMapping {
     collector.into_body_syntax_mapping(params, body)
 }
 
-pub(crate) fn body_syntax_mapping(db: &impl HirDatabase, def_id: DefId) -> Arc<BodySyntaxMapping> {
-    let def = def_id.resolve(db);
-
-    let body_syntax_mapping = match def {
-        Def::Function(f) => collect_fn_body_syntax(&f.source(db).1),
-        // TODO: consts, etc.
-        _ => panic!("Trying to get body for item type without body"),
-    };
-
+pub(crate) fn body_syntax_mapping(db: &impl HirDatabase, func: Function) -> Arc<BodySyntaxMapping> {
+    let (_, fn_def) = func.source(db);
+    let body_syntax_mapping = collect_fn_body_syntax(&fn_def);
     Arc::new(body_syntax_mapping)
 }
diff --git a/crates/ra_hir/src/generics.rs b/crates/ra_hir/src/generics.rs
index d8248ad49..64c20a462 100644
--- a/crates/ra_hir/src/generics.rs
+++ b/crates/ra_hir/src/generics.rs
@@ -5,9 +5,9 @@
 
 use std::sync::Arc;
 
-use ra_syntax::ast::{TypeParamList, AstNode, NameOwner};
+use ra_syntax::ast::{self, NameOwner, TypeParamsOwner};
 
-use crate::{db::HirDatabase, DefId, Name, AsName};
+use crate::{db::HirDatabase, Name, AsName, Function, Struct, Enum, Trait, Type};
 
 /// Data about a generic parameter (to a function, struct, impl, ...).
 #[derive(Clone, PartialEq, Eq, Debug)]
@@ -22,26 +22,53 @@ pub struct GenericParams {
     pub(crate) params: Vec<GenericParam>,
 }
 
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
+pub enum GenericDef {
+    Function(Function),
+    Struct(Struct),
+    Enum(Enum),
+    Trait(Trait),
+    Type(Type),
+}
+impl_froms!(GenericDef: Function, Struct, Enum, Trait, Type);
+
 impl GenericParams {
-    pub(crate) fn generic_params_query(db: &impl HirDatabase, def_id: DefId) -> Arc<GenericParams> {
-        let (_file_id, node) = def_id.source(db);
+    pub(crate) fn generic_params_query(
+        db: &impl HirDatabase,
+        def: GenericDef,
+    ) -> Arc<GenericParams> {
         let mut generics = GenericParams::default();
-        if let Some(type_param_list) = node.children().find_map(TypeParamList::cast) {
-            for (idx, type_param) in type_param_list.type_params().enumerate() {
-                let name = type_param
-                    .name()
-                    .map(AsName::as_name)
-                    .unwrap_or_else(Name::missing);
-                let param = GenericParam {
-                    idx: idx as u32,
-                    name,
-                };
-                generics.params.push(param);
-            }
+        match def {
+            GenericDef::Function(it) => generics.fill(&*it.source(db).1),
+            GenericDef::Struct(it) => generics.fill(&*it.source(db).1),
+            GenericDef::Enum(it) => generics.fill(&*it.source(db).1),
+            GenericDef::Trait(it) => generics.fill(&*it.source(db).1),
+            GenericDef::Type(it) => generics.fill(&*it.source(db).1),
         }
+
         Arc::new(generics)
     }
 
+    fn fill(&mut self, node: &impl TypeParamsOwner) {
+        if let Some(params) = node.type_param_list() {
+            self.fill_params(params)
+        }
+    }
+
+    fn fill_params(&mut self, params: &ast::TypeParamList) {
+        for (idx, type_param) in params.type_params().enumerate() {
+            let name = type_param
+                .name()
+                .map(AsName::as_name)
+                .unwrap_or_else(Name::missing);
+            let param = GenericParam {
+                idx: idx as u32,
+                name,
+            };
+            self.params.push(param);
+        }
+    }
+
     pub(crate) fn find_by_name(&self, name: &Name) -> Option<&GenericParam> {
         self.params.iter().find(|p| &p.name == name)
     }
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 43f0e81f9..b125a1518 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -1,22 +1,41 @@
-use ra_db::{SourceRootId, LocationIntener, FileId};
+use std::{
+    marker::PhantomData,
+    hash::{Hash, Hasher},
+};
+
+use ra_db::{LocationIntener, FileId};
 use ra_syntax::{TreeArc, SyntaxNode, SourceFile, AstNode, ast};
-use ra_arena::{Arena, RawId, impl_arena_id};
+use ra_arena::{Arena, RawId, ArenaId, impl_arena_id};
 
 use crate::{
-    HirDatabase, Def, Function, Struct, Enum, EnumVariant, ImplBlock, Crate,
-    Module, Trait, Type, Static, Const,
-    module_tree::ModuleId,
+    HirDatabase,
+    Module,
 };
 
 #[derive(Debug, Default)]
 pub struct HirInterner {
-    defs: LocationIntener<DefLoc, DefId>,
     macros: LocationIntener<MacroCallLoc, MacroCallId>,
+    fns: LocationIntener<ItemLoc<ast::FnDef>, FunctionId>,
+    structs: LocationIntener<ItemLoc<ast::StructDef>, StructId>,
+    enums: LocationIntener<ItemLoc<ast::EnumDef>, EnumId>,
+    enum_variants: LocationIntener<ItemLoc<ast::EnumVariant>, EnumVariantId>,
+    consts: LocationIntener<ItemLoc<ast::ConstDef>, ConstId>,
+    statics: LocationIntener<ItemLoc<ast::StaticDef>, StaticId>,
+    traits: LocationIntener<ItemLoc<ast::TraitDef>, TraitId>,
+    types: LocationIntener<ItemLoc<ast::TypeDef>, TypeId>,
 }
 
 impl HirInterner {
     pub fn len(&self) -> usize {
-        self.defs.len() + self.macros.len()
+        self.macros.len()
+            + self.fns.len()
+            + self.structs.len()
+            + self.enums.len()
+            + self.enum_variants.len()
+            + self.consts.len()
+            + self.statics.len()
+            + self.traits.len()
+            + self.types.len()
     }
 }
 
@@ -110,10 +129,9 @@ impl From<MacroCallId> for HirFileId {
 pub struct MacroCallId(RawId);
 impl_arena_id!(MacroCallId);
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct MacroCallLoc {
-    pub(crate) source_root_id: SourceRootId,
-    pub(crate) module_id: ModuleId,
+    pub(crate) module: Module,
     pub(crate) source_item_id: SourceItemId,
 }
 
@@ -130,117 +148,161 @@ impl MacroCallLoc {
     }
 }
 
-/// Def's are a core concept of hir. A `Def` is an Item (function, module, etc)
-/// in a specific module.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct DefId(RawId);
-impl_arena_id!(DefId);
-
-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
-pub struct DefLoc {
-    pub(crate) kind: DefKind,
-    pub(crate) source_root_id: SourceRootId,
-    pub(crate) module_id: ModuleId,
-    pub(crate) source_item_id: SourceItemId,
+#[derive(Debug)]
+pub struct ItemLoc<N: AstNode> {
+    pub(crate) module: Module,
+    raw: SourceItemId,
+    _ty: PhantomData<N>,
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
-pub(crate) enum DefKind {
-    Module,
-    Function,
-    Struct,
-    Enum,
-    EnumVariant,
-    Const,
-    Static,
-    Trait,
-    Type,
-    Item,
-
-    /// The constructor of a struct. E.g. if we have `struct Foo(usize)`, the
-    /// name `Foo` needs to resolve to different types depending on whether we
-    /// are in the types or values namespace: As a type, `Foo` of course refers
-    /// to the struct `Foo`; as a value, `Foo` is a callable type with signature
-    /// `(usize) -> Foo`. The cleanest approach to handle this seems to be to
-    /// have different defs in the two namespaces.
-    ///
-    /// rustc does the same; note that it even creates a struct constructor if
-    /// the struct isn't a tuple struct (see `CtorKind::Fictive` in rustc).
-    StructCtor,
+impl<N: AstNode> PartialEq for ItemLoc<N> {
+    fn eq(&self, other: &Self) -> bool {
+        self.module == other.module && self.raw == other.raw
+    }
+}
+impl<N: AstNode> Eq for ItemLoc<N> {}
+impl<N: AstNode> Hash for ItemLoc<N> {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        self.module.hash(hasher);
+        self.raw.hash(hasher);
+    }
 }
 
-impl DefId {
-    pub(crate) fn loc(self, db: &impl AsRef<HirInterner>) -> DefLoc {
-        db.as_ref().defs.id2loc(self)
+impl<N: AstNode> Clone for ItemLoc<N> {
+    fn clone(&self) -> ItemLoc<N> {
+        ItemLoc {
+            module: self.module,
+            raw: self.raw,
+            _ty: PhantomData,
+        }
     }
+}
 
-    pub fn resolve(self, db: &impl HirDatabase) -> Def {
-        let loc = self.loc(db);
-        match loc.kind {
-            DefKind::Module => {
-                let module = Module::from_module_id(db, loc.source_root_id, loc.module_id);
-                Def::Module(module)
-            }
-            DefKind::Function => {
-                let function = Function::new(self);
-                Def::Function(function)
-            }
-            DefKind::Struct => {
-                let struct_def = Struct::new(self);
-                Def::Struct(struct_def)
-            }
-            DefKind::Enum => Def::Enum(Enum::new(self)),
-            DefKind::EnumVariant => Def::EnumVariant(EnumVariant::new(self)),
-            DefKind::Const => {
-                let def = Const::new(self);
-                Def::Const(def)
-            }
-            DefKind::Static => {
-                let def = Static::new(self);
-                Def::Static(def)
-            }
-            DefKind::Trait => {
-                let def = Trait::new(self);
-                Def::Trait(def)
-            }
-            DefKind::Type => {
-                let def = Type::new(self);
-                Def::Type(def)
-            }
+#[derive(Clone, Copy)]
+pub(crate) struct LocationCtx<DB> {
+    db: DB,
+    module: Module,
+    file_id: HirFileId,
+}
 
-            DefKind::StructCtor => Def::Item,
-            DefKind::Item => Def::Item,
+impl<'a, DB: HirDatabase> LocationCtx<&'a DB> {
+    pub(crate) fn new(db: &'a DB, module: Module, file_id: HirFileId) -> LocationCtx<&'a DB> {
+        LocationCtx {
+            db,
+            module,
+            file_id,
         }
     }
+    pub(crate) fn to_def<N, DEF>(self, ast: &N) -> DEF
+    where
+        N: AstNode,
+        DEF: AstItemDef<N>,
+    {
+        DEF::from_ast(self, ast)
+    }
+}
+
+pub(crate) trait AstItemDef<N: AstNode>: ArenaId + Clone {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<N>, Self>;
+    fn from_ast(ctx: LocationCtx<&impl HirDatabase>, ast: &N) -> Self {
+        let items = ctx.db.file_items(ctx.file_id);
+        let raw = SourceItemId {
+            file_id: ctx.file_id,
+            item_id: Some(items.id_of(ctx.file_id, ast.syntax())),
+        };
+        let loc = ItemLoc {
+            module: ctx.module,
+            raw,
+            _ty: PhantomData,
+        };
+
+        Self::interner(ctx.db.as_ref()).loc2id(&loc)
+    }
+    fn source(self, db: &impl HirDatabase) -> (HirFileId, TreeArc<N>) {
+        let int = Self::interner(db.as_ref());
+        let loc = int.id2loc(self);
+        let syntax = db.file_item(loc.raw);
+        let ast = N::cast(&syntax)
+            .unwrap_or_else(|| panic!("invalid ItemLoc: {:?}", loc.raw))
+            .to_owned();
+        (loc.raw.file_id, ast)
+    }
+    fn module(self, db: &impl HirDatabase) -> Module {
+        let int = Self::interner(db.as_ref());
+        let loc = int.id2loc(self);
+        loc.module
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct FunctionId(RawId);
+impl_arena_id!(FunctionId);
+impl AstItemDef<ast::FnDef> for FunctionId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::FnDef>, Self> {
+        &interner.fns
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StructId(RawId);
+impl_arena_id!(StructId);
+impl AstItemDef<ast::StructDef> for StructId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::StructDef>, Self> {
+        &interner.structs
+    }
+}
 
-    pub(crate) fn source(self, db: &impl HirDatabase) -> (HirFileId, TreeArc<SyntaxNode>) {
-        let loc = self.loc(db);
-        let syntax = db.file_item(loc.source_item_id);
-        (loc.source_item_id.file_id, syntax)
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct EnumId(RawId);
+impl_arena_id!(EnumId);
+impl AstItemDef<ast::EnumDef> for EnumId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::EnumDef>, Self> {
+        &interner.enums
     }
+}
 
-    /// For a module, returns that module; for any other def, returns the containing module.
-    pub fn module(self, db: &impl HirDatabase) -> Module {
-        let loc = self.loc(db);
-        Module::from_module_id(db, loc.source_root_id, loc.module_id)
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct EnumVariantId(RawId);
+impl_arena_id!(EnumVariantId);
+impl AstItemDef<ast::EnumVariant> for EnumVariantId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::EnumVariant>, Self> {
+        &interner.enum_variants
     }
+}
 
-    /// Returns the containing crate.
-    pub fn krate(&self, db: &impl HirDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ConstId(RawId);
+impl_arena_id!(ConstId);
+impl AstItemDef<ast::ConstDef> for ConstId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::ConstDef>, Self> {
+        &interner.consts
     }
+}
 
-    /// Returns the containing impl block, if this is an impl item.
-    pub fn impl_block(self, db: &impl HirDatabase) -> Option<ImplBlock> {
-        let loc = self.loc(db);
-        let module_impls = db.impls_in_module(loc.source_root_id, loc.module_id);
-        ImplBlock::containing(module_impls, self)
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StaticId(RawId);
+impl_arena_id!(StaticId);
+impl AstItemDef<ast::StaticDef> for StaticId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::StaticDef>, Self> {
+        &interner.statics
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TraitId(RawId);
+impl_arena_id!(TraitId);
+impl AstItemDef<ast::TraitDef> for TraitId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::TraitDef>, Self> {
+        &interner.traits
     }
 }
 
-impl DefLoc {
-    pub(crate) fn id(&self, db: &impl AsRef<HirInterner>) -> DefId {
-        db.as_ref().defs.loc2id(&self)
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeId(RawId);
+impl_arena_id!(TypeId);
+impl AstItemDef<ast::TypeDef> for TypeId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::TypeDef>, Self> {
+        &interner.types
     }
 }
 
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
index 551d0d149..222e47349 100644
--- a/crates/ra_hir/src/impl_block.rs
+++ b/crates/ra_hir/src/impl_block.rs
@@ -3,14 +3,13 @@ use rustc_hash::FxHashMap;
 
 use ra_arena::{Arena, RawId, impl_arena_id};
 use ra_syntax::ast::{self, AstNode};
-use ra_db::{SourceRootId};
 
 use crate::{
-    DefId, DefLoc, DefKind, SourceItemId, SourceFileItems,
-    Function, HirInterner,
+    Const, Type,
+    Function, HirFileId,
     db::HirDatabase,
     type_ref::TypeRef,
-    module_tree::ModuleId,
+    ids::LocationCtx,
 };
 
 use crate::code_model_api::{Module, ModuleSource};
@@ -24,9 +23,9 @@ pub struct ImplBlock {
 impl ImplBlock {
     pub(crate) fn containing(
         module_impl_blocks: Arc<ModuleImplBlocks>,
-        def_id: DefId,
+        item: ImplItem,
     ) -> Option<ImplBlock> {
-        let impl_id = *module_impl_blocks.impls_by_def.get(&def_id)?;
+        let impl_id = *module_impl_blocks.impls_by_def.get(&item)?;
         Some(ImplBlock {
             module_impl_blocks,
             impl_id,
@@ -66,39 +65,25 @@ pub struct ImplData {
 
 impl ImplData {
     pub(crate) fn from_ast(
-        db: &impl AsRef<HirInterner>,
-        file_items: &SourceFileItems,
-        module: &Module,
+        db: &impl HirDatabase,
+        file_id: HirFileId,
+        module: Module,
         node: &ast::ImplBlock,
     ) -> Self {
         let target_trait = node.target_trait().map(TypeRef::from_ast);
         let target_type = TypeRef::from_ast_opt(node.target_type());
-        let module_loc = module.def_id.loc(db);
+        let ctx = LocationCtx::new(db, module, file_id);
         let items = if let Some(item_list) = node.item_list() {
             item_list
                 .impl_items()
-                .map(|item_node| {
-                    let kind = match item_node.kind() {
-                        ast::ImplItemKind::FnDef(..) => DefKind::Function,
-                        ast::ImplItemKind::ConstDef(..) => DefKind::Item,
-                        ast::ImplItemKind::TypeDef(..) => DefKind::Item,
-                    };
-                    let item_id = file_items.id_of_unchecked(item_node.syntax());
-                    let source_item_id = SourceItemId {
-                        file_id: module_loc.source_item_id.file_id,
-                        item_id: Some(item_id),
-                    };
-                    let def_loc = DefLoc {
-                        kind,
-                        source_item_id,
-                        ..module_loc
-                    };
-                    let def_id = def_loc.id(db);
-                    match item_node.kind() {
-                        ast::ImplItemKind::FnDef(..) => ImplItem::Method(Function::new(def_id)),
-                        ast::ImplItemKind::ConstDef(..) => ImplItem::Const(def_id),
-                        ast::ImplItemKind::TypeDef(..) => ImplItem::Type(def_id),
+                .map(|item_node| match item_node.kind() {
+                    ast::ImplItemKind::FnDef(it) => {
+                        ImplItem::Method(Function { id: ctx.to_def(it) })
                     }
+                    ast::ImplItemKind::ConstDef(it) => {
+                        ImplItem::Const(Const { id: ctx.to_def(it) })
+                    }
+                    ast::ImplItemKind::TypeDef(it) => ImplItem::Type(Type { id: ctx.to_def(it) }),
                 })
                 .collect()
         } else {
@@ -124,22 +109,19 @@ impl ImplData {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+//TODO: rename to ImplDef?
 pub enum ImplItem {
     Method(Function),
-    // these don't have their own types yet
-    Const(DefId),
-    Type(DefId),
+    Const(Const),
+    Type(Type),
     // Existential
 }
+impl_froms!(ImplItem: Const, Type);
 
-impl ImplItem {
-    pub fn def_id(&self) -> DefId {
-        match self {
-            ImplItem::Method(f) => f.def_id(),
-            ImplItem::Const(def_id) => *def_id,
-            ImplItem::Type(def_id) => *def_id,
-        }
+impl From<Function> for ImplItem {
+    fn from(func: Function) -> ImplItem {
+        ImplItem::Method(func)
     }
 }
 
@@ -155,7 +137,7 @@ impl_arena_id!(ImplId);
 #[derive(Debug, PartialEq, Eq)]
 pub struct ModuleImplBlocks {
     pub(crate) impls: Arena<ImplId, ImplData>,
-    impls_by_def: FxHashMap<DefId, ImplId>,
+    impls_by_def: FxHashMap<ImplItem, ImplId>,
 }
 
 impl ModuleImplBlocks {
@@ -168,6 +150,7 @@ impl ModuleImplBlocks {
 
     fn collect(&mut self, db: &impl HirDatabase, module: Module) {
         let (file_id, module_source) = module.definition_source(db);
+        let file_id: HirFileId = file_id.into();
         let node = match &module_source {
             ModuleSource::SourceFile(node) => node.syntax(),
             ModuleSource::Module(node) => node
@@ -176,25 +159,18 @@ impl ModuleImplBlocks {
                 .syntax(),
         };
 
-        let source_file_items = db.file_items(file_id.into());
-
         for impl_block_ast in node.children().filter_map(ast::ImplBlock::cast) {
-            let impl_block = ImplData::from_ast(db, &source_file_items, &module, impl_block_ast);
+            let impl_block = ImplData::from_ast(db, file_id, module, impl_block_ast);
             let id = self.impls.alloc(impl_block);
-            for impl_item in &self.impls[id].items {
-                self.impls_by_def.insert(impl_item.def_id(), id);
+            for &impl_item in &self.impls[id].items {
+                self.impls_by_def.insert(impl_item, id);
             }
         }
     }
 }
 
-pub(crate) fn impls_in_module(
-    db: &impl HirDatabase,
-    source_root_id: SourceRootId,
-    module_id: ModuleId,
-) -> Arc<ModuleImplBlocks> {
+pub(crate) fn impls_in_module(db: &impl HirDatabase, module: Module) -> Arc<ModuleImplBlocks> {
     let mut result = ModuleImplBlocks::new();
-    let module = Module::from_module_id(db, source_root_id, module_id);
     result.collect(db, module);
     Arc::new(result)
 }
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 87b5a8b8a..596f9c38c 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -5,6 +5,18 @@
 //! to a particular crate instance. That is, it has cfg flags and features
 //! applied. So, the relation between syntax and HIR is many-to-one.
 
+macro_rules! impl_froms {
+    ($e:ident: $($v:ident), *) => {
+        $(
+            impl From<$v> for $e {
+                fn from(it: $v) -> $e {
+                    $e::$v(it)
+                }
+            }
+        )*
+    }
+}
+
 pub mod db;
 #[cfg(test)]
 mod mock;
@@ -34,25 +46,26 @@ mod marks;
 use crate::{
     db::HirDatabase,
     name::{AsName, KnownName},
-    ids::{DefKind, SourceItemId, SourceFileItems},
+    ids::{SourceItemId, SourceFileItems},
 };
 
 pub use self::{
     path::{Path, PathKind},
     name::Name,
-    ids::{HirFileId, DefId, DefLoc, MacroCallId, MacroCallLoc, HirInterner},
+    ids::{HirFileId, MacroCallId, MacroCallLoc, HirInterner},
     macros::{MacroDef, MacroInput, MacroExpansion},
     nameres::{ItemMap, PerNs, Namespace, Resolution},
     ty::Ty,
     impl_block::{ImplBlock, ImplItem},
     code_model_impl::function::{FnScopes, ScopesWithSyntaxMapping},
-    docs::{Docs, Documentation}
+    docs::{Docs, Documentation},
+    adt::AdtDef,
 };
 
 pub use self::code_model_api::{
     Crate, CrateDependency,
     Def,
-    Module, ModuleSource, Problem,
+    Module, ModuleDef, ModuleSource, Problem,
     Struct, Enum, EnumVariant,
     Function, FnSignature, ScopeEntryWithSyntax,
     StructField,
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 4145c8048..361366f6a 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -35,10 +35,6 @@ impl MockDatabase {
         let file_id = db.add_file(WORKSPACE, &mut source_root, "/main.rs", text);
         db.query_mut(ra_db::SourceRootQuery)
             .set(WORKSPACE, Arc::new(source_root.clone()));
-
-        let mut crate_graph = CrateGraph::default();
-        crate_graph.add_crate_root(file_id);
-        db.set_crate_graph(crate_graph);
         (db, source_root, file_id)
     }
 
@@ -97,6 +93,8 @@ impl MockDatabase {
         text: &str,
     ) -> FileId {
         assert!(path.starts_with('/'));
+        let is_crate_root = path == "/lib.rs" || path == "/main.rs";
+
         let path = RelativePathBuf::from_path(&path[1..]).unwrap();
         let file_id = FileId(self.file_counter);
         self.file_counter += 1;
@@ -107,6 +105,12 @@ impl MockDatabase {
         self.query_mut(ra_db::FileSourceRootQuery)
             .set(file_id, source_root_id);
         source_root.files.insert(path, file_id);
+
+        if is_crate_root {
+            let mut crate_graph = CrateGraph::default();
+            crate_graph.add_crate_root(file_id);
+            self.set_crate_graph(crate_graph);
+        }
         file_id
     }
 
@@ -202,6 +206,7 @@ salsa::database_storage! {
             fn file_relative_path() for ra_db::FileRelativePathQuery;
             fn file_source_root() for ra_db::FileSourceRootQuery;
             fn source_root() for ra_db::SourceRootQuery;
+            fn source_root_crates() for ra_db::SourceRootCratesQuery;
             fn local_roots() for ra_db::LocalRootsQuery;
             fn library_roots() for ra_db::LibraryRootsQuery;
             fn crate_graph() for ra_db::CrateGraphQuery;
diff --git a/crates/ra_hir/src/module_tree.rs b/crates/ra_hir/src/module_tree.rs
index b201bf69b..c00834c4c 100644
--- a/crates/ra_hir/src/module_tree.rs
+++ b/crates/ra_hir/src/module_tree.rs
@@ -3,7 +3,7 @@ use std::sync::Arc;
 use rustc_hash::{FxHashMap, FxHashSet};
 use arrayvec::ArrayVec;
 use relative_path::RelativePathBuf;
-use ra_db::{FileId, SourceRootId, SourceRoot};
+use ra_db::{FileId, SourceRoot, CrateId};
 use ra_syntax::{
     SyntaxNode, TreeArc,
     algo::generate,
@@ -126,13 +126,10 @@ struct LinkData {
 }
 
 impl ModuleTree {
-    pub(crate) fn module_tree_query(
-        db: &impl HirDatabase,
-        source_root: SourceRootId,
-    ) -> Arc<ModuleTree> {
+    pub(crate) fn module_tree_query(db: &impl HirDatabase, crate_id: CrateId) -> Arc<ModuleTree> {
         db.check_canceled();
         let mut res = ModuleTree::default();
-        res.init(db, source_root);
+        res.init_crate(db, crate_id);
         Arc::new(res)
     }
 
@@ -145,24 +142,21 @@ impl ModuleTree {
         Some(res)
     }
 
-    fn init(&mut self, db: &impl HirDatabase, source_root: SourceRootId) {
+    fn init_crate(&mut self, db: &impl HirDatabase, crate_id: CrateId) {
+        let crate_graph = db.crate_graph();
+        let file_id = crate_graph.crate_root(crate_id);
+        let source_root_id = db.file_source_root(file_id);
+
         let mut roots = FxHashMap::default();
         let mut visited = FxHashSet::default();
 
-        let source_root = db.source_root(source_root);
-        for &file_id in source_root.files.values() {
-            let source = SourceItemId {
-                file_id: file_id.into(),
-                item_id: None,
-            };
-            if visited.contains(&source) {
-                continue; // TODO: use explicit crate_roots here
-            }
-            assert!(!roots.contains_key(&file_id));
-            let module_id =
-                self.init_subtree(db, &source_root, &mut visited, &mut roots, None, source);
-            roots.insert(file_id, module_id);
-        }
+        let source_root = db.source_root(source_root_id);
+        let source = SourceItemId {
+            file_id: file_id.into(),
+            item_id: None,
+        };
+        let module_id = self.init_subtree(db, &source_root, &mut visited, &mut roots, None, source);
+        roots.insert(file_id, module_id);
     }
 
     fn init_subtree(
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 1d163edf7..a3bc98958 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -16,19 +16,19 @@
 //! structure itself is modified.
 pub(crate) mod lower;
 
-use crate::nameres::lower::*;
-
 use std::sync::Arc;
 
+use ra_db::CrateId;
 use rustc_hash::{FxHashMap, FxHashSet};
-use ra_db::SourceRootId;
 
 use crate::{
-    DefId, DefLoc, DefKind,
+    Module, ModuleDef,
     Path, PathKind,
     HirDatabase, Crate,
     Name,
     module_tree::{ModuleId, ModuleTree},
+//FIXME: deglobify
+    nameres::lower::*,
 };
 
 /// `ItemMap` is the result of name resolution. It contains, for each
@@ -58,7 +58,7 @@ impl ModuleScope {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Resolution {
     /// None for unresolved
-    pub def_id: PerNs<DefId>,
+    pub def_id: PerNs<ModuleDef>,
     /// ident by which this is imported into local scope.
     pub import: Option<ImportId>,
 }
@@ -152,7 +152,7 @@ impl<T> PerNs<T> {
 pub(crate) struct Resolver<'a, DB> {
     db: &'a DB,
     input: &'a FxHashMap<ModuleId, Arc<LoweredModule>>,
-    source_root: SourceRootId,
+    krate: CrateId,
     module_tree: Arc<ModuleTree>,
     processed_imports: FxHashSet<(ModuleId, ImportId)>,
     result: ItemMap,
@@ -165,13 +165,13 @@ where
     pub(crate) fn new(
         db: &'a DB,
         input: &'a FxHashMap<ModuleId, Arc<LoweredModule>>,
-        source_root: SourceRootId,
-        module_tree: Arc<ModuleTree>,
+        krate: CrateId,
     ) -> Resolver<'a, DB> {
+        let module_tree = db.module_tree(krate);
         Resolver {
             db,
             input,
-            source_root,
+            krate,
             module_tree,
             processed_imports: FxHashSet::default(),
             result: ItemMap::default(),
@@ -210,7 +210,7 @@ where
                 let krate = Crate::new(crate_id);
                 for dep in krate.dependencies(self.db) {
                     if let Some(module) = dep.krate.root_module(self.db) {
-                        let def_id = module.def_id;
+                        let def_id = module.into();
                         self.add_module_item(
                             &mut module_items,
                             dep.name.clone(),
@@ -244,20 +244,22 @@ where
 
         // Populate modules
         for (name, module_id) in module_id.children(&self.module_tree) {
-            let def_loc = DefLoc {
-                kind: DefKind::Module,
-                source_root_id: self.source_root,
+            let module = Module {
                 module_id,
-                source_item_id: module_id.source(&self.module_tree),
+                krate: self.krate,
             };
-            let def_id = def_loc.id(self.db);
-            self.add_module_item(&mut module_items, name, PerNs::types(def_id));
+            self.add_module_item(&mut module_items, name, PerNs::types(module.into()));
         }
 
         self.result.per_module.insert(module_id, module_items);
     }
 
-    fn add_module_item(&self, module_items: &mut ModuleScope, name: Name, def_id: PerNs<DefId>) {
+    fn add_module_item(
+        &self,
+        module_items: &mut ModuleScope,
+        name: Name,
+        def_id: PerNs<ModuleDef>,
+    ) {
         let resolution = Resolution {
             def_id,
             import: None,
@@ -329,17 +331,11 @@ where
                     );
                     return false;
                 };
-                curr = match type_def_id.loc(self.db) {
-                    DefLoc {
-                        kind: DefKind::Module,
-                        module_id: target_module_id,
-                        source_root_id,
-                        ..
-                    } => {
-                        if source_root_id == self.source_root {
-                            target_module_id
+                curr = match type_def_id {
+                    ModuleDef::Module(module) => {
+                        if module.krate == self.krate {
+                            module.module_id
                         } else {
-                            let module = crate::code_model_api::Module::new(type_def_id);
                             let path = Path {
                                 segments: import.path.segments[i + 1..].iter().cloned().collect(),
                                 kind: PathKind::Crate,
@@ -359,7 +355,7 @@ where
                                     "resolved import {:?} ({:?}) cross-source root to {:?}",
                                     last_segment.name,
                                     import,
-                                    def_id.map(|did| did.loc(self.db))
+                                    def_id,
                                 );
                                 return true;
                             } else {
@@ -372,7 +368,7 @@ where
                         log::debug!(
                             "path segment {:?} resolved to non-module {:?}, but is not last",
                             segment.name,
-                            type_def_id.loc(self.db)
+                            type_def_id,
                         );
                         return true; // this resolved to a non-module, so the path won't ever resolve
                     }
@@ -382,7 +378,7 @@ where
                     "resolved import {:?} ({:?}) within source root to {:?}",
                     segment.name,
                     import,
-                    def_id.map(|did| did.loc(self.db))
+                    def_id,
                 );
                 self.update(module_id, |items| {
                     let res = Resolution {
diff --git a/crates/ra_hir/src/nameres/lower.rs b/crates/ra_hir/src/nameres/lower.rs
index 4eea6ff1d..b4fe99ea7 100644
--- a/crates/ra_hir/src/nameres/lower.rs
+++ b/crates/ra_hir/src/nameres/lower.rs
@@ -1,17 +1,17 @@
 use std::sync::Arc;
 
 use ra_syntax::{
-    SyntaxKind, AstNode, SourceFile, TreeArc, AstPtr,
+    AstNode, SourceFile, TreeArc, AstPtr,
     ast::{self, ModuleItemOwner, NameOwner},
 };
-use ra_db::SourceRootId;
 use ra_arena::{Arena, RawId, impl_arena_id, map::ArenaMap};
 use rustc_hash::FxHashMap;
 
 use crate::{
-    SourceItemId, Path, ModuleSource, HirDatabase, Name, SourceFileItems,
-    HirFileId, MacroCallLoc, AsName, PerNs, DefId, DefKind, DefLoc,
-    module_tree::ModuleId
+    SourceItemId, Path, ModuleSource, HirDatabase, Name,
+    HirFileId, MacroCallLoc, AsName, PerNs, Function,
+    ModuleDef, Module, Struct, Enum, Const, Static, Trait, Type,
+    ids::LocationCtx,
 };
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -32,7 +32,7 @@ pub(super) struct ImportData {
 /// can avoid redoing name resolution.
 #[derive(Debug, Default, PartialEq, Eq)]
 pub struct LoweredModule {
-    pub(crate) declarations: FxHashMap<Name, PerNs<DefId>>,
+    pub(crate) declarations: FxHashMap<Name, PerNs<ModuleDef>>,
     pub(super) imports: Arena<ImportId, ImportData>,
 }
 
@@ -59,37 +59,31 @@ impl ImportSourceMap {
 impl LoweredModule {
     pub(crate) fn lower_module_module_query(
         db: &impl HirDatabase,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
+        module: Module,
     ) -> Arc<LoweredModule> {
-        db.lower_module(source_root_id, module_id).0
+        db.lower_module(module).0
     }
 
     pub(crate) fn lower_module_source_map_query(
         db: &impl HirDatabase,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
+        module: Module,
     ) -> Arc<ImportSourceMap> {
-        db.lower_module(source_root_id, module_id).1
+        db.lower_module(module).1
     }
 
     pub(crate) fn lower_module_query(
         db: &impl HirDatabase,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
+        module: Module,
     ) -> (Arc<LoweredModule>, Arc<ImportSourceMap>) {
-        let module_tree = db.module_tree(source_root_id);
-        let source = module_id.source(&module_tree);
-        let file_id = source.file_id;
-        let source = ModuleSource::from_source_item_id(db, source);
+        let (file_id, source) = module.definition_source(db);
+        let file_id: HirFileId = file_id.into();
         let mut source_map = ImportSourceMap::default();
         let mut res = LoweredModule::default();
         match source {
             ModuleSource::SourceFile(it) => res.fill(
                 &mut source_map,
                 db,
-                source_root_id,
-                module_id,
+                module,
                 file_id,
                 &mut it.items_with_macros(),
             ),
@@ -98,8 +92,7 @@ impl LoweredModule {
                     res.fill(
                         &mut source_map,
                         db,
-                        source_root_id,
-                        module_id,
+                        module,
                         file_id,
                         &mut item_list.items_with_macros(),
                     )
@@ -113,8 +106,7 @@ impl LoweredModule {
         &mut self,
         source_map: &mut ImportSourceMap,
         db: &impl HirDatabase,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
+        module: Module,
         file_id: HirFileId,
         items: &mut Iterator<Item = ast::ItemOrMacro>,
     ) {
@@ -123,21 +115,12 @@ impl LoweredModule {
         for item in items {
             match item {
                 ast::ItemOrMacro::Item(it) => {
-                    self.add_def_id(
-                        source_map,
-                        db,
-                        source_root_id,
-                        module_id,
-                        file_id,
-                        &file_items,
-                        it,
-                    );
+                    self.add_def_id(source_map, db, module, file_id, it);
                 }
                 ast::ItemOrMacro::Macro(macro_call) => {
                     let item_id = file_items.id_of_unchecked(macro_call.syntax());
                     let loc = MacroCallLoc {
-                        source_root_id,
-                        module_id,
+                        module,
                         source_item_id: SourceItemId {
                             file_id,
                             item_id: Some(item_id),
@@ -145,18 +128,9 @@ impl LoweredModule {
                     };
                     let id = loc.id(db);
                     let file_id = HirFileId::from(id);
-                    let file_items = db.file_items(file_id);
                     //FIXME: expand recursively
                     for item in db.hir_source_file(file_id).items() {
-                        self.add_def_id(
-                            source_map,
-                            db,
-                            source_root_id,
-                            module_id,
-                            file_id,
-                            &file_items,
-                            item,
-                        );
+                        self.add_def_id(source_map, db, module, file_id, item);
                     }
                 }
             }
@@ -167,41 +141,74 @@ impl LoweredModule {
         &mut self,
         source_map: &mut ImportSourceMap,
         db: &impl HirDatabase,
-        source_root_id: SourceRootId,
-        module_id: ModuleId,
+        module: Module,
         file_id: HirFileId,
-        file_items: &SourceFileItems,
         item: &ast::ModuleItem,
     ) {
-        let name = match item.kind() {
-            ast::ModuleItemKind::StructDef(it) => it.name(),
-            ast::ModuleItemKind::EnumDef(it) => it.name(),
-            ast::ModuleItemKind::FnDef(it) => it.name(),
-            ast::ModuleItemKind::TraitDef(it) => it.name(),
-            ast::ModuleItemKind::TypeDef(it) => it.name(),
+        let ctx = LocationCtx::new(db, module, file_id);
+        match item.kind() {
+            ast::ModuleItemKind::StructDef(it) => {
+                if let Some(name) = it.name() {
+                    let s = Struct { id: ctx.to_def(it) };
+                    let s: ModuleDef = s.into();
+                    self.declarations.insert(name.as_name(), PerNs::both(s, s));
+                }
+            }
+            ast::ModuleItemKind::EnumDef(it) => {
+                if let Some(name) = it.name() {
+                    let e = Enum { id: ctx.to_def(it) };
+                    let e: ModuleDef = e.into();
+                    self.declarations.insert(name.as_name(), PerNs::types(e));
+                }
+            }
+            ast::ModuleItemKind::FnDef(it) => {
+                if let Some(name) = it.name() {
+                    let func = Function { id: ctx.to_def(it) };
+                    self.declarations
+                        .insert(name.as_name(), PerNs::values(func.into()));
+                }
+            }
+            ast::ModuleItemKind::TraitDef(it) => {
+                if let Some(name) = it.name() {
+                    let t = Trait { id: ctx.to_def(it) };
+                    self.declarations
+                        .insert(name.as_name(), PerNs::types(t.into()));
+                }
+            }
+            ast::ModuleItemKind::TypeDef(it) => {
+                if let Some(name) = it.name() {
+                    let t = Type { id: ctx.to_def(it) };
+                    self.declarations
+                        .insert(name.as_name(), PerNs::types(t.into()));
+                }
+            }
             ast::ModuleItemKind::ImplBlock(_) => {
                 // impls don't define items
-                return;
             }
             ast::ModuleItemKind::UseItem(it) => {
                 self.add_use_item(source_map, it);
-                return;
             }
             ast::ModuleItemKind::ExternCrateItem(_) => {
                 // TODO
-                return;
             }
-            ast::ModuleItemKind::ConstDef(it) => it.name(),
-            ast::ModuleItemKind::StaticDef(it) => it.name(),
+            ast::ModuleItemKind::ConstDef(it) => {
+                if let Some(name) = it.name() {
+                    let c = Const { id: ctx.to_def(it) };
+                    self.declarations
+                        .insert(name.as_name(), PerNs::values(c.into()));
+                }
+            }
+            ast::ModuleItemKind::StaticDef(it) => {
+                if let Some(name) = it.name() {
+                    let s = Static { id: ctx.to_def(it) };
+                    self.declarations
+                        .insert(name.as_name(), PerNs::values(s.into()));
+                }
+            }
             ast::ModuleItemKind::Module(_) => {
                 // modules are handled separately direclty by nameres
-                return;
             }
         };
-        if let Some(name) = name {
-            let def_id = assign_def_id(db, source_root_id, module_id, file_id, file_items, item);
-            self.declarations.insert(name.as_name(), def_id);
-        }
     }
 
     fn add_use_item(&mut self, source_map: &mut ImportSourceMap, item: &ast::UseItem) {
@@ -216,46 +223,3 @@ impl LoweredModule {
         })
     }
 }
-
-fn assign_def_id(
-    db: &impl HirDatabase,
-    source_root_id: SourceRootId,
-    module_id: ModuleId,
-    file_id: HirFileId,
-    file_items: &SourceFileItems,
-    item: &ast::ModuleItem,
-) -> PerNs<DefId> {
-    // depending on the item kind, the location can define something in
-    // the values namespace, the types namespace, or both
-    let kind = DefKind::for_syntax_kind(item.syntax().kind());
-    let def_id = kind.map(|k| {
-        let item_id = file_items.id_of_unchecked(item.syntax());
-        let def_loc = DefLoc {
-            kind: k,
-            source_root_id,
-            module_id,
-            source_item_id: SourceItemId {
-                file_id,
-                item_id: Some(item_id),
-            },
-        };
-        def_loc.id(db)
-    });
-    def_id
-}
-
-impl DefKind {
-    fn for_syntax_kind(kind: SyntaxKind) -> PerNs<DefKind> {
-        match kind {
-            SyntaxKind::FN_DEF => PerNs::values(DefKind::Function),
-            SyntaxKind::MODULE => PerNs::types(DefKind::Module),
-            SyntaxKind::STRUCT_DEF => PerNs::both(DefKind::Struct, DefKind::StructCtor),
-            SyntaxKind::ENUM_DEF => PerNs::types(DefKind::Enum),
-            SyntaxKind::TRAIT_DEF => PerNs::types(DefKind::Trait),
-            SyntaxKind::TYPE_DEF => PerNs::types(DefKind::Type),
-            SyntaxKind::CONST_DEF => PerNs::values(DefKind::Const),
-            SyntaxKind::STATIC_DEF => PerNs::values(DefKind::Static),
-            _ => PerNs::none(),
-        }
-    }
-}
diff --git a/crates/ra_hir/src/nameres/tests.rs b/crates/ra_hir/src/nameres/tests.rs
index e92007453..9322bf08c 100644
--- a/crates/ra_hir/src/nameres/tests.rs
+++ b/crates/ra_hir/src/nameres/tests.rs
@@ -1,6 +1,6 @@
 use std::sync::Arc;
 
-use ra_db::{FilesDatabase, CrateGraph, SourceRootId, salsa::Database};
+use ra_db::{CrateGraph, SourceRootId, salsa::Database};
 use relative_path::RelativePath;
 use test_utils::{assert_eq_text, covers};
 
@@ -13,10 +13,10 @@ use crate::{
 
 fn item_map(fixture: &str) -> (Arc<ItemMap>, ModuleId) {
     let (db, pos) = MockDatabase::with_position(fixture);
-    let source_root = db.file_source_root(pos.file_id);
     let module = crate::source_binder::module_from_position(&db, pos).unwrap();
-    let module_id = module.def_id.loc(&db).module_id;
-    (db.item_map(source_root), module_id)
+    let krate = module.krate(&db).unwrap();
+    let module_id = module.module_id;
+    (db.item_map(krate.crate_id), module_id)
 }
 
 fn check_module_item_map(map: &ItemMap, module_id: ModuleId, expected: &str) {
@@ -238,14 +238,13 @@ fn item_map_across_crates() {
 
     db.set_crate_graph(crate_graph);
 
-    let source_root = db.file_source_root(main_id);
     let module = crate::source_binder::module_from_file_id(&db, main_id).unwrap();
-    let module_id = module.def_id.loc(&db).module_id;
-    let item_map = db.item_map(source_root);
+    let krate = module.krate(&db).unwrap();
+    let item_map = db.item_map(krate.crate_id);
 
     check_module_item_map(
         &item_map,
-        module_id,
+        module.module_id,
         "
             Baz: t v
             test_crate: t
@@ -292,12 +291,12 @@ fn import_across_source_roots() {
     db.set_crate_graph(crate_graph);
 
     let module = crate::source_binder::module_from_file_id(&db, main_id).unwrap();
-    let module_id = module.def_id.loc(&db).module_id;
-    let item_map = db.item_map(source_root);
+    let krate = module.krate(&db).unwrap();
+    let item_map = db.item_map(krate.crate_id);
 
     check_module_item_map(
         &item_map,
-        module_id,
+        module.module_id,
         "
             C: t v
             test_crate: t
@@ -333,14 +332,13 @@ fn reexport_across_crates() {
 
     db.set_crate_graph(crate_graph);
 
-    let source_root = db.file_source_root(main_id);
     let module = crate::source_binder::module_from_file_id(&db, main_id).unwrap();
-    let module_id = module.def_id.loc(&db).module_id;
-    let item_map = db.item_map(source_root);
+    let krate = module.krate(&db).unwrap();
+    let item_map = db.item_map(krate.crate_id);
 
     check_module_item_map(
         &item_map,
-        module_id,
+        module.module_id,
         "
             Baz: t v
             test_crate: t
@@ -350,10 +348,11 @@ fn reexport_across_crates() {
 
 fn check_item_map_is_not_recomputed(initial: &str, file_change: &str) {
     let (mut db, pos) = MockDatabase::with_position(initial);
-    let source_root = db.file_source_root(pos.file_id);
+    let module = crate::source_binder::module_from_file_id(&db, pos.file_id).unwrap();
+    let krate = module.krate(&db).unwrap();
     {
         let events = db.log_executed(|| {
-            db.item_map(source_root);
+            db.item_map(krate.crate_id);
         });
         assert!(format!("{:?}", events).contains("item_map"))
     }
@@ -362,7 +361,7 @@ fn check_item_map_is_not_recomputed(initial: &str, file_change: &str) {
 
     {
         let events = db.log_executed(|| {
-            db.item_map(source_root);
+            db.item_map(krate.crate_id);
         });
         assert!(
             !format!("{:?}", events).contains("item_map"),
diff --git a/crates/ra_hir/src/query_definitions.rs b/crates/ra_hir/src/query_definitions.rs
index 074153862..cf8c7e435 100644
--- a/crates/ra_hir/src/query_definitions.rs
+++ b/crates/ra_hir/src/query_definitions.rs
@@ -7,17 +7,17 @@ use rustc_hash::FxHashMap;
 use ra_syntax::{
     AstNode, SyntaxNode, TreeArc,
 };
-use ra_db::SourceRootId;
+use ra_db::{CrateId};
 
 use crate::{
-    SourceFileItems, SourceItemId, DefId, HirFileId,
-    FnScopes,
+    SourceFileItems, SourceItemId, HirFileId,
+    Function, FnScopes, Module,
     db::HirDatabase,
     nameres::{ItemMap, Resolver},
 };
 
-pub(super) fn fn_scopes(db: &impl HirDatabase, def_id: DefId) -> Arc<FnScopes> {
-    let body = db.body_hir(def_id);
+pub(super) fn fn_scopes(db: &impl HirDatabase, func: Function) -> Arc<FnScopes> {
+    let body = db.body_hir(func);
     let res = FnScopes::new(body);
     Arc::new(res)
 }
@@ -41,15 +41,23 @@ pub(super) fn file_item(
     }
 }
 
-pub(super) fn item_map(db: &impl HirDatabase, source_root: SourceRootId) -> Arc<ItemMap> {
+pub(super) fn item_map(db: &impl HirDatabase, crate_id: CrateId) -> Arc<ItemMap> {
     let start = Instant::now();
-    let module_tree = db.module_tree(source_root);
+    let module_tree = db.module_tree(crate_id);
     let input = module_tree
         .modules()
-        .map(|id| (id, db.lower_module_module(source_root, id)))
+        .map(|module_id| {
+            (
+                module_id,
+                db.lower_module_module(Module {
+                    krate: crate_id,
+                    module_id,
+                }),
+            )
+        })
         .collect::<FxHashMap<_, _>>();
 
-    let resolver = Resolver::new(db, &input, source_root, module_tree);
+    let resolver = Resolver::new(db, &input, crate_id);
     let res = resolver.resolve();
     let elapsed = start.elapsed();
     log::info!("item_map: {:?}", elapsed);
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index bde0be37b..dbe040805 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -13,8 +13,9 @@ use ra_syntax::{
 };
 
 use crate::{
-    HirDatabase, Function, SourceItemId,
-    DefKind, DefLoc, AsName, Module,
+    HirDatabase, Function, SourceItemId, ModuleDef,
+    AsName, Module,
+    ids::LocationCtx,
 };
 
 /// Locates the module by `FileId`. Picks topmost module in the file.
@@ -84,9 +85,13 @@ pub fn module_from_child_node(
 
 fn module_from_source(db: &impl HirDatabase, source: SourceItemId) -> Option<Module> {
     let source_root_id = db.file_source_root(source.file_id.as_original_file());
-    let module_tree = db.module_tree(source_root_id);
-    let module_id = module_tree.find_module_by_source(source)?;
-    Some(Module::from_module_id(db, source_root_id, module_id))
+    db.source_root_crates(source_root_id)
+        .iter()
+        .find_map(|&krate| {
+            let module_tree = db.module_tree(krate);
+            let module_id = module_tree.find_module_by_source(source)?;
+            Some(Module { krate, module_id })
+        })
 }
 
 pub fn function_from_position(db: &impl HirDatabase, position: FilePosition) -> Option<Function> {
@@ -101,30 +106,21 @@ pub fn function_from_source(
     fn_def: &ast::FnDef,
 ) -> Option<Function> {
     let module = module_from_child_node(db, file_id, fn_def.syntax())?;
-    let res = function_from_module(db, &module, fn_def);
+    let res = function_from_module(db, module, fn_def);
     Some(res)
 }
 
 pub fn function_from_module(
     db: &impl HirDatabase,
-    module: &Module,
+    module: Module,
     fn_def: &ast::FnDef,
 ) -> Function {
-    let loc = module.def_id.loc(db);
-    let file_id = loc.source_item_id.file_id;
-    let file_items = db.file_items(file_id);
-    let item_id = file_items.id_of(file_id, fn_def.syntax());
-    let source_item_id = SourceItemId {
-        file_id,
-        item_id: Some(item_id),
-    };
-    let def_loc = DefLoc {
-        kind: DefKind::Function,
-        source_root_id: loc.source_root_id,
-        module_id: loc.module_id,
-        source_item_id,
-    };
-    Function::new(def_loc.id(db))
+    let (file_id, _) = module.definition_source(db);
+    let file_id = file_id.into();
+    let ctx = LocationCtx::new(db, module, file_id);
+    Function {
+        id: ctx.to_def(fn_def),
+    }
 }
 
 pub fn function_from_child_node(
@@ -141,15 +137,18 @@ pub fn macro_symbols(db: &impl HirDatabase, file_id: FileId) -> Vec<(SmolStr, Te
         Some(it) => it,
         None => return Vec::new(),
     };
-    let loc = module.def_id.loc(db);
-    let items = db.lower_module_module(loc.source_root_id, loc.module_id);
+    let items = db.lower_module_module(module);
     let mut res = Vec::new();
 
     for macro_call_id in items
         .declarations
         .iter()
-        .filter_map(|(_, it)| it.take_types())
-        .filter_map(|it| it.loc(db).source_item_id.file_id.as_macro_call_id())
+        .filter_map(|(_, it)| it.clone().take_types())
+        .filter_map(|it| match it {
+            ModuleDef::Trait(it) => Some(it),
+            _ => None,
+        })
+        .filter_map(|it| it.source(db).0.as_macro_call_id())
     {
         if let Some(exp) = db.expand_macro_invocation(macro_call_id) {
             let loc = macro_call_id.loc(db);
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index e690ae158..c7f77e7a3 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -24,15 +24,14 @@ use std::ops::Index;
 use std::sync::Arc;
 use std::{fmt, mem};
 
-use log;
 use ena::unify::{InPlaceUnificationTable, UnifyKey, UnifyValue, NoError};
 use ra_arena::map::ArenaMap;
 use join_to_string::join;
 use rustc_hash::FxHashMap;
 
 use crate::{
-    Def, DefId, Module, Function, Struct, StructField, Enum, EnumVariant, Path, Name, ImplBlock,
-    FnSignature, FnScopes,
+    Module, Function, Struct, StructField, Enum, EnumVariant, Path, Name, ImplBlock,
+    FnSignature, FnScopes, ModuleDef, AdtDef,
     db::HirDatabase,
     type_ref::{TypeRef, Mutability},
     name::KnownName,
@@ -184,7 +183,7 @@ pub enum Ty {
     /// Structures, enumerations and unions.
     Adt {
         /// The DefId of the struct/enum.
-        def_id: DefId,
+        def_id: AdtDef,
         /// The name, for displaying.
         name: Name,
         /// Substitutions for the generic parameters of the type.
@@ -381,12 +380,16 @@ impl Ty {
         }
 
         // Resolve in module (in type namespace)
-        let resolved = match module.resolve_path(db, path).take_types() {
-            Some(r) => r,
+        let typable: TypableDef = match module
+            .resolve_path(db, path)
+            .take_types()
+            .and_then(|it| it.into())
+        {
             None => return Ty::Unknown,
+            Some(it) => it,
         };
-        let ty = db.type_for_def(resolved);
-        let substs = Ty::substs_from_path(db, module, impl_block, generics, path, resolved);
+        let ty = db.type_for_def(typable);
+        let substs = Ty::substs_from_path(db, module, impl_block, generics, path, typable);
         ty.apply_substs(substs)
     }
 
@@ -399,20 +402,18 @@ impl Ty {
         impl_block: Option<&ImplBlock>,
         outer_generics: &GenericParams,
         path: &Path,
-        resolved: DefId,
+        resolved: TypableDef,
     ) -> Substs {
         let mut substs = Vec::new();
-        let def = resolved.resolve(db);
         let last = path
             .segments
             .last()
             .expect("path should have at least one segment");
-        let (def_generics, segment) = match def {
-            Def::Struct(s) => (s.generic_params(db), last),
-            Def::Enum(e) => (e.generic_params(db), last),
-            Def::Function(f) => (f.generic_params(db), last),
-            Def::Trait(t) => (t.generic_params(db), last),
-            Def::EnumVariant(ev) => {
+        let (def_generics, segment) = match resolved {
+            TypableDef::Function(func) => (func.generic_params(db), last),
+            TypableDef::Struct(s) => (s.generic_params(db), last),
+            TypableDef::Enum(e) => (e.generic_params(db), last),
+            TypableDef::EnumVariant(var) => {
                 // the generic args for an enum variant may be either specified
                 // on the segment referring to the enum, or on the segment
                 // referring to the variant. So `Option::<T>::None` and
@@ -426,9 +427,8 @@ impl Ty {
                     // Option::None::<T>
                     last
                 };
-                (ev.parent_enum(db).generic_params(db), segment)
+                (var.parent_enum(db).generic_params(db), segment)
             }
-            _ => return Substs::empty(),
         };
         // substs_from_path
         if let Some(generic_args) = &segment.args_and_bindings {
@@ -639,7 +639,7 @@ fn make_substs(generics: &GenericParams) -> Substs {
 fn type_for_struct(db: &impl HirDatabase, s: Struct) -> Ty {
     let generics = s.generic_params(db);
     Ty::Adt {
-        def_id: s.def_id(),
+        def_id: s.into(),
         name: s.name(db).unwrap_or_else(Name::missing),
         substs: make_substs(&generics),
     }
@@ -648,7 +648,7 @@ fn type_for_struct(db: &impl HirDatabase, s: Struct) -> Ty {
 pub(crate) fn type_for_enum(db: &impl HirDatabase, s: Enum) -> Ty {
     let generics = s.generic_params(db);
     Ty::Adt {
-        def_id: s.def_id(),
+        def_id: s.into(),
         name: s.name(db).unwrap_or_else(Name::missing),
         substs: make_substs(&generics),
     }
@@ -660,66 +660,74 @@ pub(crate) fn type_for_enum_variant(db: &impl HirDatabase, ev: EnumVariant) -> T
     type_for_enum(db, enum_parent)
 }
 
-pub(super) fn type_for_def(db: &impl HirDatabase, def_id: DefId) -> Ty {
-    let def = def_id.resolve(db);
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum TypableDef {
+    Function(Function),
+    Struct(Struct),
+    Enum(Enum),
+    EnumVariant(EnumVariant),
+}
+impl_froms!(TypableDef: Function, Struct, Enum, EnumVariant);
+
+impl From<ModuleDef> for Option<TypableDef> {
+    fn from(def: ModuleDef) -> Option<TypableDef> {
+        let res = match def {
+            ModuleDef::Function(f) => f.into(),
+            ModuleDef::Struct(s) => s.into(),
+            ModuleDef::Enum(e) => e.into(),
+            ModuleDef::EnumVariant(v) => v.into(),
+            ModuleDef::Const(_)
+            | ModuleDef::Static(_)
+            | ModuleDef::Module(_)
+            | ModuleDef::Trait(_)
+            | ModuleDef::Type(_) => return None,
+        };
+        Some(res)
+    }
+}
+
+pub(super) fn type_for_def(db: &impl HirDatabase, def: TypableDef) -> Ty {
     match def {
-        Def::Module(..) => {
-            log::debug!("trying to get type for module {:?}", def_id);
-            Ty::Unknown
-        }
-        Def::Function(f) => type_for_fn(db, f),
-        Def::Struct(s) => type_for_struct(db, s),
-        Def::Enum(e) => type_for_enum(db, e),
-        Def::EnumVariant(ev) => type_for_enum_variant(db, ev),
-        _ => {
-            log::debug!(
-                "trying to get type for item of unknown type {:?} {:?}",
-                def_id,
-                def
-            );
-            Ty::Unknown
-        }
+        TypableDef::Function(f) => type_for_fn(db, f),
+        TypableDef::Struct(s) => type_for_struct(db, s),
+        TypableDef::Enum(e) => type_for_enum(db, e),
+        TypableDef::EnumVariant(v) => type_for_enum_variant(db, v),
     }
 }
 
-pub(super) fn type_for_field(db: &impl HirDatabase, def_id: DefId, field: Name) -> Option<Ty> {
-    let def = def_id.resolve(db);
-    let (variant_data, generics) = match def {
-        Def::Struct(s) => (s.variant_data(db), s.generic_params(db)),
-        Def::EnumVariant(ev) => (ev.variant_data(db), ev.parent_enum(db).generic_params(db)),
-        // TODO: unions
-        Def::Enum(_) => {
-            // this can happen in (invalid) code, but enums don't have fields themselves
-            return None;
-        }
-        _ => panic!(
-            "trying to get type for field {:?} in non-struct/variant {:?}",
-            field, def_id
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum VariantDef {
+    Struct(Struct),
+    EnumVariant(EnumVariant),
+}
+impl_froms!(VariantDef: Struct, EnumVariant);
+
+pub(super) fn type_for_field(db: &impl HirDatabase, def: VariantDef, field: Name) -> Option<Ty> {
+    let (variant_data, generics, module) = match def {
+        VariantDef::Struct(s) => (s.variant_data(db), s.generic_params(db), s.module(db)),
+        VariantDef::EnumVariant(var) => (
+            var.variant_data(db),
+            var.parent_enum(db).generic_params(db),
+            var.module(db),
         ),
     };
-    let module = def_id.module(db);
-    let impl_block = def_id.impl_block(db);
+    // We can't have an impl block ere, right?
+    // let impl_block = def_id.impl_block(db);
     let type_ref = variant_data.get_field_type_ref(&field)?;
-    Some(Ty::from_hir(
-        db,
-        &module,
-        impl_block.as_ref(),
-        &generics,
-        &type_ref,
-    ))
+    Some(Ty::from_hir(db, &module, None, &generics, &type_ref))
 }
 
 /// The result of type inference: A mapping from expressions and patterns to types.
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct InferenceResult {
     /// For each method call expr, record the function it resolved to.
-    method_resolutions: FxHashMap<ExprId, DefId>,
+    method_resolutions: FxHashMap<ExprId, Function>,
     type_of_expr: ArenaMap<ExprId, Ty>,
     type_of_pat: ArenaMap<PatId, Ty>,
 }
 
 impl InferenceResult {
-    pub fn method_resolution(&self, expr: ExprId) -> Option<DefId> {
+    pub fn method_resolution(&self, expr: ExprId) -> Option<Function> {
         self.method_resolutions.get(&expr).map(|it| *it)
     }
 }
@@ -749,7 +757,7 @@ struct InferenceContext<'a, D: HirDatabase> {
     module: Module,
     impl_block: Option<ImplBlock>,
     var_unification_table: InPlaceUnificationTable<TypeVarId>,
-    method_resolutions: FxHashMap<ExprId, DefId>,
+    method_resolutions: FxHashMap<ExprId, Function>,
     type_of_expr: ArenaMap<ExprId, Ty>,
     type_of_pat: ArenaMap<PatId, Ty>,
     /// The return type of the function being inferred.
@@ -875,8 +883,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         self.type_of_expr.insert(expr, ty);
     }
 
-    fn write_method_resolution(&mut self, expr: ExprId, def_id: DefId) {
-        self.method_resolutions.insert(expr, def_id);
+    fn write_method_resolution(&mut self, expr: ExprId, func: Function) {
+        self.method_resolutions.insert(expr, func);
     }
 
     fn write_pat_ty(&mut self, pat: PatId, ty: Ty) {
@@ -1063,20 +1071,30 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         };
 
         // resolve in module
-        let resolved = self.module.resolve_path(self.db, &path).take_values()?;
-        let ty = self.db.type_for_def(resolved);
+        let typable: Option<TypableDef> = self
+            .module
+            .resolve_path(self.db, &path)
+            .take_values()?
+            .into();
+        let typable = typable?;
+        let ty = self.db.type_for_def(typable);
         let ty = self.insert_type_vars(ty);
         Some(ty)
     }
 
-    fn resolve_variant(&mut self, path: Option<&Path>) -> (Ty, Option<DefId>) {
+    fn resolve_variant(&mut self, path: Option<&Path>) -> (Ty, Option<VariantDef>) {
         let path = match path {
             Some(path) => path,
             None => return (Ty::Unknown, None),
         };
-        let def_id = match self.module.resolve_path(self.db, &path).take_types() {
-            Some(def_id) => def_id,
-            _ => return (Ty::Unknown, None),
+        let typable: Option<TypableDef> = self
+            .module
+            .resolve_path(self.db, &path)
+            .take_types()
+            .and_then(|it| it.into());
+        let def = match typable {
+            None => return (Ty::Unknown, None),
+            Some(it) => it,
         };
         // TODO remove the duplication between here and `Ty::from_path`?
         // TODO provide generics of function
@@ -1087,38 +1105,34 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             self.impl_block.as_ref(),
             &generics,
             path,
-            def_id,
+            def,
         );
-        match def_id.resolve(self.db) {
-            Def::Struct(s) => {
+        match def {
+            TypableDef::Struct(s) => {
                 let ty = type_for_struct(self.db, s);
                 let ty = self.insert_type_vars(ty.apply_substs(substs));
-                (ty, Some(def_id))
+                (ty, Some(s.into()))
             }
-            Def::EnumVariant(ev) => {
-                let ty = type_for_enum_variant(self.db, ev);
+            TypableDef::EnumVariant(var) => {
+                let ty = type_for_enum_variant(self.db, var);
                 let ty = self.insert_type_vars(ty.apply_substs(substs));
-                (ty, Some(def_id))
+                (ty, Some(var.into()))
             }
-            _ => (Ty::Unknown, None),
+            TypableDef::Enum(_) | TypableDef::Function(_) => (Ty::Unknown, None),
         }
     }
 
     fn resolve_fields(&mut self, path: Option<&Path>) -> Option<(Ty, Vec<StructField>)> {
-        let (ty, def_id) = self.resolve_variant(path);
-        let def_id = def_id?;
-        let def = def_id.resolve(self.db);
-
-        match def {
-            Def::Struct(s) => {
+        let (ty, def) = self.resolve_variant(path);
+        match def? {
+            VariantDef::Struct(s) => {
                 let fields = s.fields(self.db);
                 Some((ty, fields))
             }
-            Def::EnumVariant(ev) => {
-                let fields = ev.fields(self.db);
+            VariantDef::EnumVariant(var) => {
+                let fields = var.fields(self.db);
                 Some((ty, fields))
             }
-            _ => None,
         }
     }
 
@@ -1216,6 +1230,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 .module
                 .resolve_path(self.db, &path)
                 .take_values()
+                .and_then(|module_def| module_def.into())
                 .map_or(Ty::Unknown, |resolved| self.db.type_for_def(resolved)),
             Pat::Bind {
                 mode,
@@ -1336,9 +1351,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let receiver_ty = self.infer_expr(*receiver, &Expectation::none());
                 let resolved = receiver_ty.clone().lookup_method(self.db, method_name);
                 let method_ty = match resolved {
-                    Some(def_id) => {
-                        self.write_method_resolution(expr, def_id);
-                        self.db.type_for_def(def_id)
+                    Some(func) => {
+                        self.write_method_resolution(expr, func);
+                        self.db.type_for_def(func.into())
                     }
                     None => Ty::Unknown,
                 };
@@ -1407,7 +1422,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 for field in fields {
                     let field_ty = if let Some(def_id) = def_id {
                         self.db
-                            .type_for_field(def_id, field.name.clone())
+                            .type_for_field(def_id.into(), field.name.clone())
                             .unwrap_or(Ty::Unknown)
                             .subst(&substs)
                     } else {
@@ -1431,10 +1446,12 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                             i.and_then(|i| fields.get(i).cloned())
                         }
                         Ty::Adt {
-                            def_id, ref substs, ..
+                            def_id: AdtDef::Struct(s),
+                            ref substs,
+                            ..
                         } => self
                             .db
-                            .type_for_field(def_id, name.clone())
+                            .type_for_field(s.into(), name.clone())
                             .map(|ty| ty.subst(substs)),
                         _ => None,
                     })
@@ -1607,16 +1624,15 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     }
 }
 
-pub fn infer(db: &impl HirDatabase, def_id: DefId) -> Arc<InferenceResult> {
+pub fn infer(db: &impl HirDatabase, func: Function) -> Arc<InferenceResult> {
     db.check_canceled();
-    let function = Function::new(def_id); // TODO: consts also need inference
-    let body = function.body(db);
-    let scopes = db.fn_scopes(def_id);
-    let module = function.module(db);
-    let impl_block = function.impl_block(db);
+    let body = func.body(db);
+    let scopes = db.fn_scopes(func);
+    let module = func.module(db);
+    let impl_block = func.impl_block(db);
     let mut ctx = InferenceContext::new(db, body, scopes, module, impl_block);
 
-    let signature = function.signature(db);
+    let signature = func.signature(db);
     ctx.collect_fn_signature(&signature);
 
     ctx.infer_body();
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 9f65c5fe1..9a571c2aa 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -6,19 +6,17 @@ use std::sync::Arc;
 
 use rustc_hash::FxHashMap;
 
-use ra_db::SourceRootId;
-
 use crate::{
-    HirDatabase, DefId, module_tree::ModuleId, Module, Crate, Name, Function,
+    HirDatabase, module_tree::ModuleId, Module, Crate, Name, Function,
     impl_block::{ImplId, ImplBlock, ImplItem},
-    generics::GenericParams
+    generics::GenericParams,
+    ty::{AdtDef, Ty}
 };
-use super::Ty;
 
 /// This is used as a key for indexing impls.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub enum TyFingerprint {
-    Adt(DefId),
+    Adt(AdtDef),
     // we'll also want to index impls for primitive types etc.
 }
 
@@ -37,7 +35,7 @@ impl TyFingerprint {
 #[derive(Debug, PartialEq, Eq)]
 pub struct CrateImplBlocks {
     /// To make sense of the ModuleIds, we need the source root.
-    source_root_id: SourceRootId,
+    krate: Crate,
     impls: FxHashMap<TyFingerprint, Vec<(ModuleId, ImplId)>>,
 }
 
@@ -53,14 +51,17 @@ impl CrateImplBlocks {
             .into_iter()
             .flat_map(|i| i.iter())
             .map(move |(module_id, impl_id)| {
-                let module_impl_blocks = db.impls_in_module(self.source_root_id, *module_id);
+                let module = Module {
+                    krate: self.krate.crate_id,
+                    module_id: *module_id,
+                };
+                let module_impl_blocks = db.impls_in_module(module);
                 ImplBlock::from_id(module_impl_blocks, *impl_id)
             })
     }
 
-    fn collect_recursive(&mut self, db: &impl HirDatabase, module: Module) {
-        let module_id = module.def_id.loc(db).module_id;
-        let module_impl_blocks = db.impls_in_module(self.source_root_id, module_id);
+    fn collect_recursive(&mut self, db: &impl HirDatabase, module: &Module) {
+        let module_impl_blocks = db.impls_in_module(module.clone());
 
         for (impl_id, impl_data) in module_impl_blocks.impls.iter() {
             let impl_block = ImplBlock::from_id(Arc::clone(&module_impl_blocks), impl_id);
@@ -81,13 +82,13 @@ impl CrateImplBlocks {
                     self.impls
                         .entry(target_ty_fp)
                         .or_insert_with(Vec::new)
-                        .push((module_id, impl_id));
+                        .push((module.module_id, impl_id));
                 }
             }
         }
 
         for child in module.children(db) {
-            self.collect_recursive(db, child);
+            self.collect_recursive(db, &child);
         }
     }
 
@@ -95,15 +96,12 @@ impl CrateImplBlocks {
         db: &impl HirDatabase,
         krate: Crate,
     ) -> Arc<CrateImplBlocks> {
-        let crate_graph = db.crate_graph();
-        let file_id = crate_graph.crate_root(krate.crate_id);
-        let source_root_id = db.file_source_root(file_id);
         let mut crate_impl_blocks = CrateImplBlocks {
-            source_root_id,
+            krate: krate.clone(),
             impls: FxHashMap::default(),
         };
         if let Some(module) = krate.root_module(db) {
-            crate_impl_blocks.collect_recursive(db, module);
+            crate_impl_blocks.collect_recursive(db, &module);
         }
         Arc::new(crate_impl_blocks)
     }
@@ -120,11 +118,11 @@ impl Ty {
     // TODO: cache this as a query?
     // - if so, what signature? (TyFingerprint, Name)?
     // - or maybe cache all names and def_ids of methods per fingerprint?
-    pub fn lookup_method(self, db: &impl HirDatabase, name: &Name) -> Option<DefId> {
+    pub fn lookup_method(self, db: &impl HirDatabase, name: &Name) -> Option<Function> {
         self.iterate_methods(db, |f| {
             let sig = f.signature(db);
             if sig.name() == name && sig.has_self_param() {
-                Some(f.def_id())
+                Some(f)
             } else {
                 None
             }
diff --git a/crates/ra_hir/src/ty/snapshots/tests__infer_struct.snap b/crates/ra_hir/src/ty/snapshots/tests__infer_struct.snap
index c4a2d5cf8..8747fae18 100644
--- a/crates/ra_hir/src/ty/snapshots/tests__infer_struct.snap
+++ b/crates/ra_hir/src/ty/snapshots/tests__infer_struct.snap
@@ -1,19 +1,19 @@
 ---
-created: "2019-01-22T14:45:00.058678600+00:00"
-creator: insta@0.4.0
+created: "2019-01-24T14:51:32.808861856+00:00"
+creator: insta@0.5.2
 expression: "&result"
-source: "crates\\ra_hir\\src\\ty\\tests.rs"
+source: crates/ra_hir/src/ty/tests.rs
 ---
 [72; 154) '{     ...a.c; }': ()
 [82; 83) 'c': [unknown]
-[86; 87) 'C': [unknown]
+[86; 87) 'C': C
 [86; 90) 'C(1)': [unknown]
 [88; 89) '1': i32
-[96; 97) 'B': [unknown]
+[96; 97) 'B': B
 [107; 108) 'a': A
 [114; 133) 'A { b:...C(1) }': A
 [121; 122) 'B': B
-[127; 128) 'C': [unknown]
+[127; 128) 'C': C
 [127; 131) 'C(1)': C
 [129; 130) '1': i32
 [139; 140) 'a': A