23 files changed, 402 insertions, 363 deletions
diff --git a/Cargo.lock b/Cargo.lock
index c7ec98226..66ff1285a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1003,6 +1003,7 @@ dependencies = [
 "ra_arena 0.1.0",
 "ra_cfg 0.1.0",
 "ra_db 0.1.0",
+ "ra_hir_def 0.1.0",
 "ra_hir_expand 0.1.0",
 "ra_mbe 0.1.0",
 "ra_prof 0.1.0",
@@ -1014,6 +1015,18 @@ dependencies = [
 ]
 [[package]]
+name = "ra_hir_def"
+version = "0.1.0"
+dependencies = [
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ra_arena 0.1.0",
+ "ra_db 0.1.0",
+ "ra_hir_expand 0.1.0",
+ "ra_prof 0.1.0",
+ "ra_syntax 0.1.0",
+]
+[[package]]
 name = "ra_hir_expand"
 version = "0.1.0"
 dependencies = [
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index 143dae6bd..5df371bc0 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -20,6 +20,7 @@ ra_db = { path = "../ra_db" }
 mbe = { path = "../ra_mbe", package = "ra_mbe" }
 tt = { path = "../ra_tt", package = "ra_tt" }
 hir_expand = { path = "../ra_hir_expand", package = "ra_hir_expand" }
+hir_def = { path = "../ra_hir_def", package = "ra_hir_def" }
 test_utils = { path = "../test_utils" }
 ra_prof = { path = "../ra_prof" }
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 8eb3c577d..1a790b2f3 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -5,6 +5,7 @@ pub(crate) mod docs;
 use std::sync::Arc;
+use hir_def::{CrateModuleId, ModuleId};
 use ra_db::{CrateId, Edition, FileId};
 use ra_syntax::ast::{self, NameOwner, TypeAscriptionOwner};
@@ -23,7 +24,7 @@ use crate::{
        BOOL, CHAR, F32, F64, I128, I16, I32, I64, I8, ISIZE, SELF_TYPE, STR, U128, U16, U32, U64,
        U8, USIZE,
    },
-    nameres::{CrateModuleId, ImportId, ModuleScope, Namespace},
+    nameres::{ImportId, ModuleScope, Namespace},
    resolve::{Resolver, Scope, TypeNs},
    traits::TraitData,
    ty::{
@@ -67,8 +68,7 @@ impl Crate {
    pub fn root_module(self, db: &impl DefDatabase) -> Option<Module> {
        let module_id = db.crate_def_map(self).root();
-        let module = Module { krate: self, module_id };
+        Some(Module::new(self, module_id))
-        Some(module)
    }
    pub fn edition(self, db: &impl DefDatabase) -> Edition {
@@ -83,8 +83,7 @@ impl Crate {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Module {
-    pub(crate) krate: Crate,
+    pub(crate) id: ModuleId,
-    pub(crate) module_id: CrateModuleId,
 }
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -175,12 +174,16 @@ impl ModuleSource {
 }
 impl Module {
+    pub(crate) fn new(krate: Crate, crate_module_id: CrateModuleId) -> Module {
+        Module { id: ModuleId { krate: krate.crate_id, module_id: crate_module_id } }
+    }
    /// Name of this module.
    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let parent = def_map[self.module_id].parent?;
+        let parent = def_map[self.id.module_id].parent?;
        def_map[parent].children.iter().find_map(|(name, module_id)| {
-            if *module_id == self.module_id {
+            if *module_id == self.id.module_id {
                Some(name.clone())
            } else {
                None
@@ -200,29 +203,29 @@ impl Module {
    }
    /// Returns the crate this module is part of.
-    pub fn krate(self, _db: &impl DefDatabase) -> Option<Crate> {
+    pub fn krate(self) -> Crate {
-        Some(self.krate)
+        Crate { crate_id: self.id.krate }
    }
    /// Topmost parent of this module. Every module has a `crate_root`, but some
    /// might be missing `krate`. This can happen if a module's file is not included
    /// in the module tree of any target in `Cargo.toml`.
    pub fn crate_root(self, db: &impl DefDatabase) -> Module {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
        self.with_module_id(def_map.root())
    }
    /// Finds a child module with the specified name.
    pub fn child(self, db: &impl HirDatabase, name: &Name) -> Option<Module> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let child_id = def_map[self.module_id].children.get(name)?;
+        let child_id = def_map[self.id.module_id].children.get(name)?;
        Some(self.with_module_id(*child_id))
    }
    /// Iterates over all child modules.
    pub fn children(self, db: &impl DefDatabase) -> impl Iterator<Item = Module> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let children = def_map[self.module_id]
+        let children = def_map[self.id.module_id]
            .children
            .iter()
            .map(|(_, module_id)| self.with_module_id(*module_id))
@@ -232,8 +235,8 @@ impl Module {
    /// Finds a parent module.
    pub fn parent(self, db: &impl DefDatabase) -> Option<Module> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let parent_id = def_map[self.module_id].parent?;
+        let parent_id = def_map[self.id.module_id].parent?;
        Some(self.with_module_id(parent_id))
    }
@@ -249,11 +252,11 @@ impl Module {
    /// Returns a `ModuleScope`: a set of items, visible in this module.
    pub fn scope(self, db: &impl HirDatabase) -> ModuleScope {
-        db.crate_def_map(self.krate)[self.module_id].scope.clone()
+        db.crate_def_map(self.krate())[self.id.module_id].scope.clone()
    }
    pub fn diagnostics(self, db: &impl HirDatabase, sink: &mut DiagnosticSink) {
-        db.crate_def_map(self.krate).add_diagnostics(db, self.module_id, sink);
+        db.crate_def_map(self.krate()).add_diagnostics(db, self.id.module_id, sink);
        for decl in self.declarations(db) {
            match decl {
                crate::ModuleDef::Function(f) => f.diagnostics(db, sink),
@@ -277,13 +280,13 @@ impl Module {
    }
    pub(crate) fn resolver(self, db: &impl DefDatabase) -> Resolver {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        Resolver::default().push_module_scope(def_map, self.module_id)
+        Resolver::default().push_module_scope(def_map, self.id.module_id)
    }
    pub fn declarations(self, db: &impl DefDatabase) -> Vec<ModuleDef> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        def_map[self.module_id]
+        def_map[self.id.module_id]
            .scope
            .entries()
            .filter_map(|(_name, res)| if res.import.is_none() { Some(res.def) } else { None })
@@ -303,7 +306,7 @@ impl Module {
    }
    fn with_module_id(self, module_id: CrateModuleId) -> Module {
-        Module { module_id, krate: self.krate }
+        Module::new(self.krate(), module_id)
    }
 }
@@ -340,11 +343,11 @@ pub struct Struct {
 impl Struct {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
@@ -402,7 +405,7 @@ impl Union {
    }
    pub fn module(self, db: &impl HirDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn ty(self, db: &impl HirDatabase) -> Ty {
@@ -428,11 +431,11 @@ pub struct Enum {
 impl Enum {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
@@ -523,12 +526,14 @@ impl Adt {
    }
    pub fn krate(self, db: &impl HirDatabase) -> Option<Crate> {
-        match self {
+        Some(
-            Adt::Struct(s) => s.module(db),
+            match self {
-            Adt::Union(s) => s.module(db),
+                Adt::Struct(s) => s.module(db),
-            Adt::Enum(e) => e.module(db),
+                Adt::Union(s) => s.module(db),
-        }
+                Adt::Enum(e) => e.module(db),
-        .krate(db)
+            }
+            .krate(),
+        )
    }
    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
@@ -692,11 +697,11 @@ impl FnData {
 impl Function {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn name(self, db: &impl HirDatabase) -> Name {
@@ -770,11 +775,11 @@ pub struct Const {
 impl Const {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn data(self, db: &impl HirDatabase) -> Arc<ConstData> {
@@ -867,11 +872,11 @@ pub struct Static {
 impl Static {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn data(self, db: &impl HirDatabase) -> Arc<ConstData> {
@@ -896,7 +901,7 @@ pub struct Trait {
 impl Trait {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
@@ -998,11 +1003,11 @@ pub struct TypeAlias {
 impl TypeAlias {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    /// The containing impl block, if this is a method.
diff --git a/crates/ra_hir/src/code_model/src.rs b/crates/ra_hir/src/code_model/src.rs
index fdae26906..5c7f61eef 100644
--- a/crates/ra_hir/src/code_model/src.rs
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -1,9 +1,6 @@
 //! FIXME: write short doc here
-use ra_syntax::{
+use ra_syntax::ast::{self, AstNode};
-    ast::{self, AstNode},
-    SyntaxNode,
-};
 use crate::{
    db::{AstDatabase, DefDatabase, HirDatabase},
@@ -12,34 +9,21 @@ use crate::{
    ModuleSource, Static, Struct, StructField, Trait, TypeAlias, Union,
 };
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub use hir_def::Source;
-pub struct Source<T> {
-    pub file_id: HirFileId,
-    pub ast: T,
-}
 pub trait HasSource {
    type Ast;
    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<Self::Ast>;
 }
-impl<T> Source<T> {
-    pub(crate) fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
-        Source { file_id: self.file_id, ast: f(self.ast) }
-    }
-    pub(crate) fn file_syntax(&self, db: &impl AstDatabase) -> SyntaxNode {
-        db.parse_or_expand(self.file_id).expect("source created from invalid file")
-    }
-}
 /// NB: Module is !HasSource, because it has two source nodes at the same time:
 /// definition and declaration.
 impl Module {
    /// Returns a node which defines this module. That is, a file or a `mod foo {}` with items.
    pub fn definition_source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<ModuleSource> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let decl_id = def_map[self.module_id].declaration;
+        let decl_id = def_map[self.id.module_id].declaration;
-        let file_id = def_map[self.module_id].definition;
+        let file_id = def_map[self.id.module_id].definition;
        let ast = ModuleSource::new(db, file_id, decl_id);
        let file_id = file_id.map(HirFileId::from).unwrap_or_else(|| decl_id.unwrap().file_id());
        Source { file_id, ast }
@@ -51,8 +35,8 @@ impl Module {
        self,
        db: &(impl DefDatabase + AstDatabase),
    ) -> Option<Source<ast::Module>> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let decl = def_map[self.module_id].declaration?;
+        let decl = def_map[self.id.module_id].declaration?;
        let ast = decl.to_node(db);
        Some(Source { file_id: decl.file_id(), ast })
    }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 6d34c671d..8f6cb2da7 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -2,8 +2,8 @@
 use std::sync::Arc;
-use ra_db::{salsa, SourceDatabase};
+use ra_db::salsa;
-use ra_syntax::{ast, SmolStr};
+use ra_syntax::SmolStr;
 use crate::{
    adt::{EnumData, StructData},
@@ -23,40 +23,12 @@ use crate::{
    Static, Struct, StructField, Trait, TypeAlias,
 };
+pub use hir_def::db::{InternDatabase, InternDatabaseStorage};
 pub use hir_expand::db::{
    AstDatabase, AstDatabaseStorage, AstIdMapQuery, MacroArgQuery, MacroDefQuery, MacroExpandQuery,
    ParseMacroQuery,
 };
-/// We store all interned things in the single QueryGroup.
-///
-/// This is done mainly to allow both "volatile" `AstDatabase` and "stable"
-/// `DefDatabase` to access macros, without adding hard dependencies between the
-/// two.
-#[salsa::query_group(InternDatabaseStorage)]
-pub trait InternDatabase: SourceDatabase {
-    #[salsa::interned]
-    fn intern_function(&self, loc: ids::ItemLoc<ast::FnDef>) -> ids::FunctionId;
-    #[salsa::interned]
-    fn intern_struct(&self, loc: ids::ItemLoc<ast::StructDef>) -> ids::StructId;
-    #[salsa::interned]
-    fn intern_enum(&self, loc: ids::ItemLoc<ast::EnumDef>) -> ids::EnumId;
-    #[salsa::interned]
-    fn intern_const(&self, loc: ids::ItemLoc<ast::ConstDef>) -> ids::ConstId;
-    #[salsa::interned]
-    fn intern_static(&self, loc: ids::ItemLoc<ast::StaticDef>) -> ids::StaticId;
-    #[salsa::interned]
-    fn intern_trait(&self, loc: ids::ItemLoc<ast::TraitDef>) -> ids::TraitId;
-    #[salsa::interned]
-    fn intern_type_alias(&self, loc: ids::ItemLoc<ast::TypeAliasDef>) -> ids::TypeAliasId;
-    // Interned IDs for Chalk integration
-    #[salsa::interned]
-    fn intern_type_ctor(&self, type_ctor: TypeCtor) -> ids::TypeCtorId;
-    #[salsa::interned]
-    fn intern_impl(&self, impl_: Impl) -> ids::GlobalImplId;
-}
 // This database uses `AstDatabase` internally,
 #[salsa::query_group(DefDatabaseStorage)]
 #[salsa::requires(AstDatabase)]
@@ -176,6 +148,12 @@ pub trait HirDatabase: DefDatabase + AstDatabase {
    #[salsa::invoke(crate::ty::traits::trait_solver_query)]
    fn trait_solver(&self, krate: Crate) -> crate::ty::traits::TraitSolver;
+    // Interned IDs for Chalk integration
+    #[salsa::interned]
+    fn intern_type_ctor(&self, type_ctor: TypeCtor) -> ids::TypeCtorId;
+    #[salsa::interned]
+    fn intern_impl(&self, impl_: Impl) -> ids::GlobalImplId;
    #[salsa::invoke(crate::ty::traits::chalk::associated_ty_data_query)]
    fn associated_ty_data(&self, id: chalk_ir::TypeId) -> Arc<chalk_rust_ir::AssociatedTyDatum>;
diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
index 7954c04b2..93713bb14 100644
--- a/crates/ra_hir/src/from_source.rs
+++ b/crates/ra_hir/src/from_source.rs
@@ -195,7 +195,7 @@ impl Module {
            .find_map(|krate| {
                let def_map = db.crate_def_map(krate);
                let module_id = def_map.find_module_by_source(src.file_id, decl_id)?;
-                Some(Module { krate, module_id })
+                Some(Module::new(krate, module_id))
            })
    }
 }
@@ -208,6 +208,6 @@ where
    let module_src =
        crate::ModuleSource::from_child_node(db, src.file_id.original_file(db), &src.ast.syntax());
    let module = Module::from_definition(db, Source { file_id: src.file_id, ast: module_src })?;
-    let ctx = LocationCtx::new(db, module, src.file_id);
+    let ctx = LocationCtx::new(db, module.id, src.file_id);
    Some(DEF::from_ast(ctx, &src.ast))
 }
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index dea288eb7..fe083c0c6 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -5,16 +5,12 @@
 //! This module defines a bunch of ids we are using. The most important ones are
 //! probably `HirFileId` and `DefId`.
-use std::hash::{Hash, Hasher};
 use ra_db::salsa;
-use ra_syntax::{ast, AstNode};
-use crate::{
+pub use hir_def::{
-    db::{AstDatabase, InternDatabase},
+    AstItemDef, ConstId, EnumId, FunctionId, ItemLoc, LocationCtx, StaticId, StructId, TraitId,
-    AstId, FileAstId, Module, Source,
+    TypeAliasId,
 };
 pub use hir_expand::{HirFileId, MacroCallId, MacroCallLoc, MacroDefId, MacroFile, MacroFileKind};
 macro_rules! impl_intern_key {
@@ -30,163 +26,6 @@ macro_rules! impl_intern_key {
    };
 }
-#[derive(Debug)]
-pub struct ItemLoc<N: AstNode> {
-    pub(crate) module: Module,
-    ast_id: AstId<N>,
-}
-impl<N: AstNode> PartialEq for ItemLoc<N> {
-    fn eq(&self, other: &Self) -> bool {
-        self.module == other.module && self.ast_id == other.ast_id
-    }
-}
-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.ast_id.hash(hasher);
-    }
-}
-impl<N: AstNode> Clone for ItemLoc<N> {
-    fn clone(&self) -> ItemLoc<N> {
-        ItemLoc { module: self.module, ast_id: self.ast_id }
-    }
-}
-#[derive(Clone, Copy)]
-pub(crate) struct LocationCtx<DB> {
-    db: DB,
-    module: Module,
-    file_id: HirFileId,
-}
-impl<'a, DB> LocationCtx<&'a DB> {
-    pub(crate) fn new(db: &'a DB, module: Module, file_id: HirFileId) -> LocationCtx<&'a DB> {
-        LocationCtx { db, module, file_id }
-    }
-}
-impl<'a, DB: AstDatabase + InternDatabase> LocationCtx<&'a DB> {
-    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>: salsa::InternKey + Clone {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<N>) -> Self;
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<N>;
-    fn from_ast(ctx: LocationCtx<&(impl AstDatabase + InternDatabase)>, ast: &N) -> Self {
-        let items = ctx.db.ast_id_map(ctx.file_id);
-        let item_id = items.ast_id(ast);
-        Self::from_ast_id(ctx, item_id)
-    }
-    fn from_ast_id(ctx: LocationCtx<&impl InternDatabase>, ast_id: FileAstId<N>) -> Self {
-        let loc = ItemLoc { module: ctx.module, ast_id: AstId::new(ctx.file_id, ast_id) };
-        Self::intern(ctx.db, loc)
-    }
-    fn source(self, db: &(impl AstDatabase + InternDatabase)) -> Source<N> {
-        let loc = self.lookup_intern(db);
-        let ast = loc.ast_id.to_node(db);
-        Source { file_id: loc.ast_id.file_id(), ast }
-    }
-    fn module(self, db: &impl InternDatabase) -> Module {
-        let loc = self.lookup_intern(db);
-        loc.module
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct FunctionId(salsa::InternId);
-impl_intern_key!(FunctionId);
-impl AstItemDef<ast::FnDef> for FunctionId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::FnDef>) -> Self {
-        db.intern_function(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::FnDef> {
-        db.lookup_intern_function(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StructId(salsa::InternId);
-impl_intern_key!(StructId);
-impl AstItemDef<ast::StructDef> for StructId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
-        db.intern_struct(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StructDef> {
-        db.lookup_intern_struct(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct EnumId(salsa::InternId);
-impl_intern_key!(EnumId);
-impl AstItemDef<ast::EnumDef> for EnumId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::EnumDef>) -> Self {
-        db.intern_enum(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::EnumDef> {
-        db.lookup_intern_enum(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct ConstId(salsa::InternId);
-impl_intern_key!(ConstId);
-impl AstItemDef<ast::ConstDef> for ConstId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::ConstDef>) -> Self {
-        db.intern_const(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::ConstDef> {
-        db.lookup_intern_const(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StaticId(salsa::InternId);
-impl_intern_key!(StaticId);
-impl AstItemDef<ast::StaticDef> for StaticId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StaticDef>) -> Self {
-        db.intern_static(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StaticDef> {
-        db.lookup_intern_static(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct TraitId(salsa::InternId);
-impl_intern_key!(TraitId);
-impl AstItemDef<ast::TraitDef> for TraitId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TraitDef>) -> Self {
-        db.intern_trait(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TraitDef> {
-        db.lookup_intern_trait(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct TypeAliasId(salsa::InternId);
-impl_intern_key!(TypeAliasId);
-impl AstItemDef<ast::TypeAliasDef> for TypeAliasId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TypeAliasDef>) -> Self {
-        db.intern_type_alias(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TypeAliasDef> {
-        db.lookup_intern_type_alias(self)
-    }
-}
 /// This exists just for Chalk, because Chalk just has a single `StructId` where
 /// we have different kinds of ADTs, primitive types and special type
 /// constructors like tuples and function pointers.
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
index 1a5223680..06f21fc33 100644
--- a/crates/ra_hir/src/impl_block.rs
+++ b/crates/ra_hir/src/impl_block.rs
@@ -129,7 +129,7 @@ impl ImplData {
    ) -> Self {
        let target_trait = node.target_trait().map(TypeRef::from_ast);
        let target_type = TypeRef::from_ast_opt(node.target_type());
-        let ctx = LocationCtx::new(db, module, file_id);
+        let ctx = LocationCtx::new(db, module.id, file_id);
        let negative = node.is_negative();
        let items = if let Some(item_list) = node.item_list() {
            item_list
@@ -182,7 +182,7 @@ impl ModuleImplBlocks {
    ) -> (Arc<ModuleImplBlocks>, Arc<ImplSourceMap>) {
        let mut source_map = ImplSourceMap::default();
        let crate_graph = db.crate_graph();
-        let cfg_options = crate_graph.cfg_options(module.krate.crate_id());
+        let cfg_options = crate_graph.cfg_options(module.id.krate);
        let result = ModuleImplBlocks::collect(db, cfg_options, module, &mut source_map);
        (Arc::new(result), Arc::new(source_map))
diff --git a/crates/ra_hir/src/lang_item.rs b/crates/ra_hir/src/lang_item.rs
index 6c4e8ffbd..e1780ed38 100644
--- a/crates/ra_hir/src/lang_item.rs
+++ b/crates/ra_hir/src/lang_item.rs
@@ -22,14 +22,14 @@ pub enum LangItemTarget {
 impl LangItemTarget {
    pub(crate) fn krate(&self, db: &impl HirDatabase) -> Option<Crate> {
-        match self {
+        Some(match self {
-            LangItemTarget::Enum(e) => e.module(db).krate(db),
+            LangItemTarget::Enum(e) => e.module(db).krate(),
-            LangItemTarget::Function(f) => f.module(db).krate(db),
+            LangItemTarget::Function(f) => f.module(db).krate(),
-            LangItemTarget::ImplBlock(i) => i.module().krate(db),
+            LangItemTarget::ImplBlock(i) => i.module().krate(),
-            LangItemTarget::Static(s) => s.module(db).krate(db),
+            LangItemTarget::Static(s) => s.module(db).krate(),
-            LangItemTarget::Struct(s) => s.module(db).krate(db),
+            LangItemTarget::Struct(s) => s.module(db).krate(),
-            LangItemTarget::Trait(t) => t.module(db).krate(db),
+            LangItemTarget::Trait(t) => t.module(db).krate(),
-        }
+        })
    }
 }
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 67adcfa28..b325979f5 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -56,8 +56,9 @@ mod tests;
 use std::sync::Arc;
+use hir_def::CrateModuleId;
 use once_cell::sync::Lazy;
-use ra_arena::{impl_arena_id, Arena, RawId};
+use ra_arena::Arena;
 use ra_db::{Edition, FileId};
 use ra_prof::profile;
 use ra_syntax::ast;
@@ -115,13 +116,8 @@ impl std::ops::Index<CrateModuleId> for CrateDefMap {
    }
 }
-/// An ID of a module, **local** to a specific crate
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub(crate) struct CrateModuleId(RawId);
-impl_arena_id!(CrateModuleId);
 #[derive(Default, Debug, PartialEq, Eq)]
-pub(crate) struct ModuleData {
+pub struct ModuleData {
    pub(crate) parent: Option<CrateModuleId>,
    pub(crate) children: FxHashMap<Name, CrateModuleId>,
    pub(crate) scope: ModuleScope,
@@ -335,7 +331,7 @@ impl CrateDefMap {
            PathKind::DollarCrate(krate) => {
                if krate == self.krate {
                    tested_by!(macro_dollar_crate_self);
-                    PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
+                    PerNs::types(Module::new(self.krate, self.root).into())
                } else {
                    match krate.root_module(db) {
                        Some(module) => {
@@ -346,12 +342,8 @@ impl CrateDefMap {
                    }
                }
            }
-            PathKind::Crate => {
+            PathKind::Crate => PerNs::types(Module::new(self.krate, self.root).into()),
-                PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
+            PathKind::Self_ => PerNs::types(Module::new(self.krate, original_module).into()),
-            }
-            PathKind::Self_ => {
-                PerNs::types(Module { krate: self.krate, module_id: original_module }.into())
-            }
            // plain import or absolute path in 2015: crate-relative with
            // fallback to extern prelude (with the simplification in
            // rust-lang/rust#57745)
@@ -377,7 +369,7 @@ impl CrateDefMap {
            }
            PathKind::Super => {
                if let Some(p) = self.modules[original_module].parent {
-                    PerNs::types(Module { krate: self.krate, module_id: p }.into())
+                    PerNs::types(Module::new(self.krate, p).into())
                } else {
                    log::debug!("super path in root module");
                    return ResolvePathResult::empty(ReachedFixedPoint::Yes);
@@ -419,12 +411,12 @@ impl CrateDefMap {
            curr_per_ns = match curr {
                ModuleDef::Module(module) => {
-                    if module.krate != self.krate {
+                    if module.krate() != self.krate {
                        let path =
                            Path { segments: path.segments[i..].to_vec(), kind: PathKind::Self_ };
                        log::debug!("resolving {:?} in other crate", path);
-                        let defp_map = db.crate_def_map(module.krate);
+                        let defp_map = db.crate_def_map(module.krate());
-                        let (def, s) = defp_map.resolve_path(db, module.module_id, &path);
+                        let (def, s) = defp_map.resolve_path(db, module.id.module_id, &path);
                        return ResolvePathResult::with(
                            def,
                            ReachedFixedPoint::Yes,
@@ -433,7 +425,7 @@ impl CrateDefMap {
                    }
                    // Since it is a qualified path here, it should not contains legacy macros
-                    match self[module.module_id].scope.get(&segment.name) {
+                    match self[module.id.module_id].scope.get(&segment.name) {
                        Some(res) => res.def,
                        _ => {
                            log::debug!("path segment {:?} not found", segment.name);
@@ -511,14 +503,14 @@ impl CrateDefMap {
    fn resolve_in_prelude(&self, db: &impl DefDatabase, name: &Name) -> PerNs {
        if let Some(prelude) = self.prelude {
            let keep;
-            let def_map = if prelude.krate == self.krate {
+            let def_map = if prelude.krate() == self.krate {
                self
            } else {
                // Extend lifetime
-                keep = db.crate_def_map(prelude.krate);
+                keep = db.crate_def_map(prelude.krate());
                &keep
            };
-            def_map[prelude.module_id].scope.get(name).map_or_else(PerNs::none, |res| res.def)
+            def_map[prelude.id.module_id].scope.get(name).map_or_else(PerNs::none, |res| res.def)
        } else {
            PerNs::none()
        }
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index dc591e8d3..a94a0554c 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -212,7 +212,7 @@ where
        if let Some(ModuleDef::Module(m)) = res.take_types() {
            tested_by!(macro_rules_from_other_crates_are_visible_with_macro_use);
-            self.import_all_macros_exported(current_module_id, m.krate);
+            self.import_all_macros_exported(current_module_id, m.krate());
        }
    }
@@ -289,11 +289,11 @@ where
                    if import.is_prelude {
                        tested_by!(std_prelude);
                        self.def_map.prelude = Some(m);
-                    } else if m.krate != self.def_map.krate {
+                    } else if m.krate() != self.def_map.krate {
                        tested_by!(glob_across_crates);
                        // glob import from other crate => we can just import everything once
-                        let item_map = self.db.crate_def_map(m.krate);
+                        let item_map = self.db.crate_def_map(m.krate());
-                        let scope = &item_map[m.module_id].scope;
+                        let scope = &item_map[m.id.module_id].scope;
                        // Module scoped macros is included
                        let items = scope
@@ -307,7 +307,7 @@ where
                        // glob import from same crate => we do an initial
                        // import, and then need to propagate any further
                        // additions
-                        let scope = &self.def_map[m.module_id].scope;
+                        let scope = &self.def_map[m.id.module_id].scope;
                        // Module scoped macros is included
                        let items = scope
@@ -319,7 +319,7 @@ where
                        self.update(module_id, Some(import_id), &items);
                        // record the glob import in case we add further items
                        self.glob_imports
-                            .entry(m.module_id)
+                            .entry(m.id.module_id)
                            .or_default()
                            .push((module_id, import_id));
                    }
@@ -523,9 +523,10 @@ where
        // Prelude module is always considered to be `#[macro_use]`.
        if let Some(prelude_module) = self.def_collector.def_map.prelude {
-            if prelude_module.krate != self.def_collector.def_map.krate {
+            if prelude_module.krate() != self.def_collector.def_map.krate {
                tested_by!(prelude_is_macro_use);
-                self.def_collector.import_all_macros_exported(self.module_id, prelude_module.krate);
+                self.def_collector
+                    .import_all_macros_exported(self.module_id, prelude_module.krate());
            }
        }
@@ -631,9 +632,7 @@ where
        modules[res].scope.legacy_macros = modules[self.module_id].scope.legacy_macros.clone();
        modules[self.module_id].children.insert(name.clone(), res);
        let resolution = Resolution {
-            def: PerNs::types(
+            def: PerNs::types(Module::new(self.def_collector.def_map.krate, res).into()),
-                Module { krate: self.def_collector.def_map.krate, module_id: res }.into(),
-            ),
            import: None,
        };
        self.def_collector.update(self.module_id, None, &[(name, resolution)]);
@@ -641,8 +640,8 @@ where
    }
    fn define_def(&mut self, def: &raw::DefData) {
-        let module = Module { krate: self.def_collector.def_map.krate, module_id: self.module_id };
+        let module = Module::new(self.def_collector.def_map.krate, self.module_id);
-        let ctx = LocationCtx::new(self.def_collector.db, module, self.file_id);
+        let ctx = LocationCtx::new(self.def_collector.db, module.id, self.file_id);
        macro_rules! def {
            ($kind:ident, $ast_id:ident) => {
diff --git a/crates/ra_hir/src/resolve.rs b/crates/ra_hir/src/resolve.rs
index 3c797c0c3..8b6269407 100644
--- a/crates/ra_hir/src/resolve.rs
+++ b/crates/ra_hir/src/resolve.rs
@@ -1,6 +1,7 @@
 //! Name resolution.
 use std::sync::Arc;
+use hir_def::CrateModuleId;
 use rustc_hash::FxHashSet;
 use crate::{
@@ -13,7 +14,7 @@ use crate::{
    generics::GenericParams,
    impl_block::ImplBlock,
    name::{Name, SELF_PARAM, SELF_TYPE},
-    nameres::{CrateDefMap, CrateModuleId, PerNs},
+    nameres::{CrateDefMap, PerNs},
    path::{Path, PathKind},
    Adt, BuiltinType, Const, Enum, EnumVariant, Function, MacroDef, ModuleDef, Static, Struct,
    Trait, TypeAlias,
@@ -330,8 +331,8 @@ impl Resolver {
        for scope in &self.scopes {
            if let Scope::ModuleScope(m) = scope {
                if let Some(prelude) = m.crate_def_map.prelude() {
-                    let prelude_def_map = db.crate_def_map(prelude.krate);
+                    let prelude_def_map = db.crate_def_map(prelude.krate());
-                    traits.extend(prelude_def_map[prelude.module_id].scope.traits());
+                    traits.extend(prelude_def_map[prelude.id.module_id].scope.traits());
                }
                traits.extend(m.crate_def_map[m.module_id].scope.traits());
            }
@@ -444,10 +445,12 @@ impl Scope {
                    f(name.clone(), ScopeDef::ModuleDef(*def));
                });
                if let Some(prelude) = m.crate_def_map.prelude() {
-                    let prelude_def_map = db.crate_def_map(prelude.krate);
+                    let prelude_def_map = db.crate_def_map(prelude.krate());
-                    prelude_def_map[prelude.module_id].scope.entries().for_each(|(name, res)| {
+                    prelude_def_map[prelude.id.module_id].scope.entries().for_each(
-                        f(name.clone(), res.def.into());
+                        |(name, res)| {
-                    });
+                            f(name.clone(), res.def.into());
+                        },
+                    );
                }
            }
            Scope::GenericParams(gp) => {
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index a907d6a9f..730c33226 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -64,7 +64,7 @@ fn def_with_body_from_child_node(
 ) -> Option<DefWithBody> {
    let src = crate::ModuleSource::from_child_node(db, file_id, node);
    let module = Module::from_definition(db, crate::Source { file_id: file_id.into(), ast: src })?;
-    let ctx = LocationCtx::new(db, module, file_id.into());
+    let ctx = LocationCtx::new(db, module.id, file_id.into());
    node.ancestors().find_map(|node| {
        if let Some(def) = ast::FnDef::cast(node.clone()) {
diff --git a/crates/ra_hir/src/traits.rs b/crates/ra_hir/src/traits.rs
index e39511518..22f188049 100644
--- a/crates/ra_hir/src/traits.rs
+++ b/crates/ra_hir/src/traits.rs
@@ -27,7 +27,7 @@ impl TraitData {
        let src = tr.source(db);
        let name = src.ast.name().map(|n| n.as_name());
        let module = tr.module(db);
-        let ctx = LocationCtx::new(db, module, src.file_id);
+        let ctx = LocationCtx::new(db, module.id, src.file_id);
        let auto = src.ast.is_auto();
        let items = if let Some(item_list) = src.ast.item_list() {
            item_list
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index ad2ab560d..50583a142 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -5,13 +5,13 @@
 use std::sync::Arc;
 use arrayvec::ArrayVec;
+use hir_def::CrateModuleId;
 use rustc_hash::FxHashMap;
 use super::{autoderef, lower, Canonical, InEnvironment, TraitEnvironment, TraitRef};
 use crate::{
    db::HirDatabase,
    impl_block::{ImplBlock, ImplId},
-    nameres::CrateModuleId,
    resolve::Resolver,
    ty::primitive::{FloatBitness, UncertainFloatTy, UncertainIntTy},
    ty::{Ty, TypeCtor},
@@ -50,7 +50,7 @@ impl CrateImplBlocks {
        let fingerprint = TyFingerprint::for_impl(ty);
        fingerprint.and_then(|f| self.impls.get(&f)).into_iter().flat_map(|i| i.iter()).map(
            move |(module_id, impl_id)| {
-                let module = Module { krate: self.krate, module_id: *module_id };
+                let module = Module::new(self.krate, *module_id);
                ImplBlock::from_id(module, *impl_id)
            },
        )
@@ -62,7 +62,7 @@ impl CrateImplBlocks {
    ) -> impl Iterator<Item = ImplBlock> + 'a {
        self.impls_by_trait.get(&tr).into_iter().flat_map(|i| i.iter()).map(
            move |(module_id, impl_id)| {
-                let module = Module { krate: self.krate, module_id: *module_id };
+                let module = Module::new(self.krate, *module_id);
                ImplBlock::from_id(module, *impl_id)
            },
        )
@@ -71,7 +71,7 @@ impl CrateImplBlocks {
    pub fn all_impls<'a>(&'a self) -> impl Iterator<Item = ImplBlock> + 'a {
        self.impls.values().chain(self.impls_by_trait.values()).flat_map(|i| i.iter()).map(
            move |(module_id, impl_id)| {
-                let module = Module { krate: self.krate, module_id: *module_id };
+                let module = Module::new(self.krate, *module_id);
                ImplBlock::from_id(module, *impl_id)
            },
        )
@@ -90,14 +90,14 @@ impl CrateImplBlocks {
                    self.impls_by_trait
                        .entry(tr.trait_)
                        .or_insert_with(Vec::new)
-                        .push((module.module_id, impl_id));
+                        .push((module.id.module_id, impl_id));
                }
            } else {
                if let Some(target_ty_fp) = TyFingerprint::for_impl(&target_ty) {
                    self.impls
                        .entry(target_ty_fp)
                        .or_insert_with(Vec::new)
-                        .push((module.module_id, impl_id));
+                        .push((module.id.module_id, impl_id));
                }
            }
        }
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index e18c28cf6..ab66515be 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -162,11 +162,11 @@ impl ToChalk for Trait {
    type Chalk = chalk_ir::TraitId;
    fn to_chalk(self, _db: &impl HirDatabase) -> chalk_ir::TraitId {
-        self.id.into()
+        chalk_ir::TraitId(id_to_chalk(self.id))
    }
    fn from_chalk(_db: &impl HirDatabase, trait_id: chalk_ir::TraitId) -> Trait {
-        Trait { id: trait_id.into() }
+        Trait { id: id_from_chalk(trait_id.0) }
    }
 }
@@ -198,11 +198,11 @@ impl ToChalk for TypeAlias {
    type Chalk = chalk_ir::TypeId;
    fn to_chalk(self, _db: &impl HirDatabase) -> chalk_ir::TypeId {
-        self.id.into()
+        chalk_ir::TypeId(id_to_chalk(self.id))
    }
-    fn from_chalk(_db: &impl HirDatabase, impl_id: chalk_ir::TypeId) -> TypeAlias {
+    fn from_chalk(_db: &impl HirDatabase, type_alias_id: chalk_ir::TypeId) -> TypeAlias {
-        TypeAlias { id: impl_id.into() }
+        TypeAlias { id: id_from_chalk(type_alias_id.0) }
    }
 }
@@ -537,7 +537,7 @@ pub(crate) fn trait_datum_query(
    let trait_ref = trait_.trait_ref(db).subst(&bound_vars).to_chalk(db);
    let flags = chalk_rust_ir::TraitFlags {
        auto: trait_.is_auto(db),
-        upstream: trait_.module(db).krate(db) != Some(krate),
+        upstream: trait_.module(db).krate() != krate,
        non_enumerable: true,
        // FIXME set these flags correctly
        marker: false,
@@ -625,7 +625,7 @@ fn impl_block_datum(
        .target_trait_ref(db)
        .expect("FIXME handle unresolved impl block trait ref")
        .subst(&bound_vars);
-    let impl_type = if impl_block.module().krate(db) == Some(krate) {
+    let impl_type = if impl_block.module().krate() == krate {
        chalk_rust_ir::ImplType::Local
    } else {
        chalk_rust_ir::ImplType::External
@@ -775,30 +775,6 @@ fn id_to_chalk<T: InternKey>(salsa_id: T) -> chalk_ir::RawId {
    chalk_ir::RawId { index: salsa_id.as_intern_id().as_u32() }
 }
-impl From<chalk_ir::TraitId> for crate::ids::TraitId {
-    fn from(trait_id: chalk_ir::TraitId) -> Self {
-        id_from_chalk(trait_id.0)
-    }
-}
-impl From<crate::ids::TraitId> for chalk_ir::TraitId {
-    fn from(trait_id: crate::ids::TraitId) -> Self {
-        chalk_ir::TraitId(id_to_chalk(trait_id))
-    }
-}
-impl From<chalk_ir::TypeId> for crate::ids::TypeAliasId {
-    fn from(type_id: chalk_ir::TypeId) -> Self {
-        id_from_chalk(type_id.0)
-    }
-}
-impl From<crate::ids::TypeAliasId> for chalk_ir::TypeId {
-    fn from(type_id: crate::ids::TypeAliasId) -> Self {
-        chalk_ir::TypeId(id_to_chalk(type_id))
-    }
-}
 impl From<chalk_ir::StructId> for crate::ids::TypeCtorId {
    fn from(struct_id: chalk_ir::StructId) -> Self {
        id_from_chalk(struct_id.0)
diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
new file mode 100644
index 000000000..75e93f254
--- /dev/null
+++ b/crates/ra_hir_def/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+edition = "2018"
+name = "ra_hir_def"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+[dependencies]
+log = "0.4.5"
+ra_arena = { path = "../ra_arena" }
+ra_db = { path = "../ra_db" }
+ra_syntax = { path = "../ra_syntax" }
+ra_prof = { path = "../ra_prof" }
+hir_expand = { path = "../ra_hir_expand", package = "ra_hir_expand" }
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
new file mode 100644
index 000000000..f6f976c86
--- /dev/null
+++ b/crates/ra_hir_def/src/db.rs
@@ -0,0 +1,22 @@
+//! Defines database & queries for name resolution.
+use ra_db::{salsa, SourceDatabase};
+use ra_syntax::ast;
+#[salsa::query_group(InternDatabaseStorage)]
+pub trait InternDatabase: SourceDatabase {
+    #[salsa::interned]
+    fn intern_function(&self, loc: crate::ItemLoc<ast::FnDef>) -> crate::FunctionId;
+    #[salsa::interned]
+    fn intern_struct(&self, loc: crate::ItemLoc<ast::StructDef>) -> crate::StructId;
+    #[salsa::interned]
+    fn intern_enum(&self, loc: crate::ItemLoc<ast::EnumDef>) -> crate::EnumId;
+    #[salsa::interned]
+    fn intern_const(&self, loc: crate::ItemLoc<ast::ConstDef>) -> crate::ConstId;
+    #[salsa::interned]
+    fn intern_static(&self, loc: crate::ItemLoc<ast::StaticDef>) -> crate::StaticId;
+    #[salsa::interned]
+    fn intern_trait(&self, loc: crate::ItemLoc<ast::TraitDef>) -> crate::TraitId;
+    #[salsa::interned]
+    fn intern_type_alias(&self, loc: crate::ItemLoc<ast::TypeAliasDef>) -> crate::TypeAliasId;
+}
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
new file mode 100644
index 000000000..4d6b9db03
--- /dev/null
+++ b/crates/ra_hir_def/src/lib.rs
@@ -0,0 +1,216 @@
+//! `hir_def` crate contains everything between macro expansion and type
+//! inference.
+//!
+//! It defines various items (structs, enums, traits) which comprises Rust code,
+//! as well as an algorithm for resolving paths to such entities.
+//!
+//! Note that `hir_def` is a work in progress, so not all of the above is
+//! actually true.
+pub mod db;
+use std::hash::{Hash, Hasher};
+use hir_expand::{ast_id_map::FileAstId, db::AstDatabase, AstId, HirFileId};
+use ra_arena::{impl_arena_id, RawId};
+use ra_db::{salsa, CrateId};
+use ra_syntax::{ast, AstNode, SyntaxNode};
+use crate::db::InternDatabase;
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub struct Source<T> {
+    pub file_id: HirFileId,
+    pub ast: T,
+}
+impl<T> Source<T> {
+    pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
+        Source { file_id: self.file_id, ast: f(self.ast) }
+    }
+    pub fn file_syntax(&self, db: &impl AstDatabase) -> SyntaxNode {
+        db.parse_or_expand(self.file_id).expect("source created from invalid file")
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ModuleId {
+    pub krate: CrateId,
+    pub module_id: CrateModuleId,
+}
+/// An ID of a module, **local** to a specific crate
+// FIXME: rename to `LocalModuleId`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct CrateModuleId(RawId);
+impl_arena_id!(CrateModuleId);
+macro_rules! impl_intern_key {
+    ($name:ident) => {
+        impl salsa::InternKey for $name {
+            fn from_intern_id(v: salsa::InternId) -> Self {
+                $name(v)
+            }
+            fn as_intern_id(&self) -> salsa::InternId {
+                self.0
+            }
+        }
+    };
+}
+#[derive(Debug)]
+pub struct ItemLoc<N: AstNode> {
+    pub(crate) module: ModuleId,
+    ast_id: AstId<N>,
+}
+impl<N: AstNode> PartialEq for ItemLoc<N> {
+    fn eq(&self, other: &Self) -> bool {
+        self.module == other.module && self.ast_id == other.ast_id
+    }
+}
+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.ast_id.hash(hasher);
+    }
+}
+impl<N: AstNode> Clone for ItemLoc<N> {
+    fn clone(&self) -> ItemLoc<N> {
+        ItemLoc { module: self.module, ast_id: self.ast_id }
+    }
+}
+#[derive(Clone, Copy)]
+pub struct LocationCtx<DB> {
+    db: DB,
+    module: ModuleId,
+    file_id: HirFileId,
+}
+impl<'a, DB> LocationCtx<&'a DB> {
+    pub fn new(db: &'a DB, module: ModuleId, file_id: HirFileId) -> LocationCtx<&'a DB> {
+        LocationCtx { db, module, file_id }
+    }
+}
+impl<'a, DB: AstDatabase + InternDatabase> LocationCtx<&'a DB> {
+    pub fn to_def<N, DEF>(self, ast: &N) -> DEF
+    where
+        N: AstNode,
+        DEF: AstItemDef<N>,
+    {
+        DEF::from_ast(self, ast)
+    }
+}
+pub trait AstItemDef<N: AstNode>: salsa::InternKey + Clone {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<N>) -> Self;
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<N>;
+    fn from_ast(ctx: LocationCtx<&(impl AstDatabase + InternDatabase)>, ast: &N) -> Self {
+        let items = ctx.db.ast_id_map(ctx.file_id);
+        let item_id = items.ast_id(ast);
+        Self::from_ast_id(ctx, item_id)
+    }
+    fn from_ast_id(ctx: LocationCtx<&impl InternDatabase>, ast_id: FileAstId<N>) -> Self {
+        let loc = ItemLoc { module: ctx.module, ast_id: AstId::new(ctx.file_id, ast_id) };
+        Self::intern(ctx.db, loc)
+    }
+    fn source(self, db: &(impl AstDatabase + InternDatabase)) -> Source<N> {
+        let loc = self.lookup_intern(db);
+        let ast = loc.ast_id.to_node(db);
+        Source { file_id: loc.ast_id.file_id(), ast }
+    }
+    fn module(self, db: &impl InternDatabase) -> ModuleId {
+        let loc = self.lookup_intern(db);
+        loc.module
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct FunctionId(salsa::InternId);
+impl_intern_key!(FunctionId);
+impl AstItemDef<ast::FnDef> for FunctionId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::FnDef>) -> Self {
+        db.intern_function(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::FnDef> {
+        db.lookup_intern_function(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StructId(salsa::InternId);
+impl_intern_key!(StructId);
+impl AstItemDef<ast::StructDef> for StructId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
+        db.intern_struct(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StructDef> {
+        db.lookup_intern_struct(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct EnumId(salsa::InternId);
+impl_intern_key!(EnumId);
+impl AstItemDef<ast::EnumDef> for EnumId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::EnumDef>) -> Self {
+        db.intern_enum(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::EnumDef> {
+        db.lookup_intern_enum(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ConstId(salsa::InternId);
+impl_intern_key!(ConstId);
+impl AstItemDef<ast::ConstDef> for ConstId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::ConstDef>) -> Self {
+        db.intern_const(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::ConstDef> {
+        db.lookup_intern_const(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StaticId(salsa::InternId);
+impl_intern_key!(StaticId);
+impl AstItemDef<ast::StaticDef> for StaticId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StaticDef>) -> Self {
+        db.intern_static(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StaticDef> {
+        db.lookup_intern_static(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TraitId(salsa::InternId);
+impl_intern_key!(TraitId);
+impl AstItemDef<ast::TraitDef> for TraitId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TraitDef>) -> Self {
+        db.intern_trait(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TraitDef> {
+        db.lookup_intern_trait(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeAliasId(salsa::InternId);
+impl_intern_key!(TypeAliasId);
+impl AstItemDef<ast::TypeAliasDef> for TypeAliasId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TypeAliasDef>) -> Self {
+        db.intern_type_alias(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TypeAliasDef> {
+        db.lookup_intern_type_alias(self)
+    }
+}
diff --git a/crates/ra_ide_api/src/completion/complete_path.rs b/crates/ra_ide_api/src/completion/complete_path.rs
index 23dece73c..956d8ce49 100644
--- a/crates/ra_ide_api/src/completion/complete_path.rs
+++ b/crates/ra_ide_api/src/completion/complete_path.rs
@@ -50,7 +50,7 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
                hir::ModuleDef::TypeAlias(a) => a.ty(ctx.db),
                _ => unreachable!(),
            };
-            let krate = ctx.module.and_then(|m| m.krate(ctx.db));
+            let krate = ctx.module.map(|m| m.krate());
            if let Some(krate) = krate {
                ty.iterate_impl_items(ctx.db, krate, |item| {
                    match item {
diff --git a/crates/ra_ide_api/src/impls.rs b/crates/ra_ide_api/src/impls.rs
index 7fc1b1efa..b899ed3a5 100644
--- a/crates/ra_ide_api/src/impls.rs
+++ b/crates/ra_ide_api/src/impls.rs
@@ -51,7 +51,7 @@ fn impls_for_def(
        }
    };
-    let krate = module.krate(db)?;
+    let krate = module.krate();
    let impls = db.impls_in_crate(krate);
    Some(
@@ -72,7 +72,7 @@ fn impls_for_trait(
    let src = hir::Source { file_id: position.file_id.into(), ast: node.clone() };
    let tr = hir::Trait::from_source(db, src)?;
-    let krate = module.krate(db)?;
+    let krate = module.krate();
    let impls = db.impls_in_crate(krate);
    Some(
diff --git a/crates/ra_ide_api/src/parent_module.rs b/crates/ra_ide_api/src/parent_module.rs
index 566509849..4c57566e2 100644
--- a/crates/ra_ide_api/src/parent_module.rs
+++ b/crates/ra_ide_api/src/parent_module.rs
@@ -27,10 +27,7 @@ pub(crate) fn crate_for(db: &RootDatabase, file_id: FileId) -> Vec<CrateId> {
            Some(it) => it,
            None => return Vec::new(),
        };
-    let krate = match module.krate(db) {
+    let krate = module.krate();
-        Some(it) => it,
-        None => return Vec::new(),
-    };
    vec![krate.crate_id()]
 }
diff --git a/crates/ra_ide_api/src/references/search_scope.rs b/crates/ra_ide_api/src/references/search_scope.rs
index b6eb248b7..dbd1af597 100644
--- a/crates/ra_ide_api/src/references/search_scope.rs
+++ b/crates/ra_ide_api/src/references/search_scope.rs
@@ -120,7 +120,7 @@ impl NameDefinition {
                return SearchScope::new(res);
            }
            if vis.as_str() == "pub" {
-                let krate = self.container.krate(db).unwrap();
+                let krate = self.container.krate();
                let crate_graph = db.crate_graph();
                for crate_id in crate_graph.iter() {
                    let mut crate_deps = crate_graph.dependencies(crate_id);