14 files changed, 139 insertions, 100 deletions

diff --git a/Cargo.lock b/Cargo.lock
index c7ec98226..a76433620 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 +1015,17 @@ 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_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..3f1c36941 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)
+        Some(Module::new(self, module_id))
     }
 
     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) module_id: CrateModuleId,
+    pub(crate) id: ModuleId,
 }
 
 #[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 parent = def_map[self.module_id].parent?;
+        let def_map = db.crate_def_map(self.krate());
+        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> {
-        Some(self.krate)
+    pub fn krate(self) -> Crate {
+        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 child_id = def_map[self.module_id].children.get(name)?;
+        let def_map = db.crate_def_map(self.krate());
+        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 children = def_map[self.module_id]
+        let def_map = db.crate_def_map(self.krate());
+        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 parent_id = def_map[self.module_id].parent?;
+        let def_map = db.crate_def_map(self.krate());
+        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);
-        Resolver::default().push_module_scope(def_map, self.module_id)
+        let def_map = db.crate_def_map(self.krate());
+        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);
-        def_map[self.module_id]
+        let def_map = db.crate_def_map(self.krate());
+        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)
     }
 }
 
@@ -344,7 +347,7 @@ impl Struct {
     }
 
     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> {
@@ -432,7 +435,7 @@ impl Enum {
     }
 
     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 {
-            Adt::Struct(s) => s.module(db),
-            Adt::Union(s) => s.module(db),
-            Adt::Enum(e) => e.module(db),
-        }
-        .krate(db)
+        Some(
+            match self {
+                Adt::Struct(s) => s.module(db),
+                Adt::Union(s) => s.module(db),
+                Adt::Enum(e) => e.module(db),
+            }
+            .krate(),
+        )
     }
 
     pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
@@ -696,7 +701,7 @@ impl Function {
     }
 
     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 {
@@ -774,7 +779,7 @@ impl Const {
     }
 
     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> {
@@ -871,7 +876,7 @@ impl Static {
     }
 
     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> {
@@ -1002,7 +1007,7 @@ impl TypeAlias {
     }
 
     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..8b33f25f7 100644
--- a/crates/ra_hir/src/code_model/src.rs
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -37,9 +37,9 @@ impl<T> Source<T> {
 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 decl_id = def_map[self.module_id].declaration;
-        let file_id = def_map[self.module_id].definition;
+        let def_map = db.crate_def_map(self.krate());
+        let decl_id = def_map[self.id.module_id].declaration;
+        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 +51,8 @@ impl Module {
         self,
         db: &(impl DefDatabase + AstDatabase),
     ) -> Option<Source<ast::Module>> {
-        let def_map = db.crate_def_map(self.krate);
-        let decl = def_map[self.module_id].declaration?;
+        let def_map = db.crate_def_map(self.krate());
+        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/from_source.rs b/crates/ra_hir/src/from_source.rs
index 7954c04b2..291f2a14a 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))
             })
     }
 }
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
index 1a5223680..fde47c264 100644
--- a/crates/ra_hir/src/impl_block.rs
+++ b/crates/ra_hir/src/impl_block.rs
@@ -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 {
-            LangItemTarget::Enum(e) => e.module(db).krate(db),
-            LangItemTarget::Function(f) => f.module(db).krate(db),
-            LangItemTarget::ImplBlock(i) => i.module().krate(db),
-            LangItemTarget::Static(s) => s.module(db).krate(db),
-            LangItemTarget::Struct(s) => s.module(db).krate(db),
-            LangItemTarget::Trait(t) => t.module(db).krate(db),
-        }
+        Some(match self {
+            LangItemTarget::Enum(e) => e.module(db).krate(),
+            LangItemTarget::Function(f) => f.module(db).krate(),
+            LangItemTarget::ImplBlock(i) => i.module().krate(),
+            LangItemTarget::Static(s) => s.module(db).krate(),
+            LangItemTarget::Struct(s) => s.module(db).krate(),
+            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 => {
-                PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
-            }
-            PathKind::Self_ => {
-                PerNs::types(Module { krate: self.krate, module_id: original_module }.into())
-            }
+            PathKind::Crate => PerNs::types(Module::new(self.krate, self.root).into()),
+            PathKind::Self_ => PerNs::types(Module::new(self.krate, 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 (def, s) = defp_map.resolve_path(db, module.module_id, &path);
+                        let defp_map = db.crate_def_map(module.krate());
+                        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..dd5f9d4ba 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 scope = &item_map[m.module_id].scope;
+                        let item_map = self.db.crate_def_map(m.krate());
+                        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(
-                Module { krate: self.def_collector.def_map.krate, module_id: res }.into(),
-            ),
+            def: PerNs::types(Module::new(self.def_collector.def_map.krate, res).into()),
             import: None,
         };
         self.def_collector.update(self.module_id, None, &[(name, resolution)]);
@@ -641,7 +640,7 @@ 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);
 
         macro_rules! def {
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);
-                    traits.extend(prelude_def_map[prelude.module_id].scope.traits());
+                    let prelude_def_map = db.crate_def_map(prelude.krate());
+                    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);
-                    prelude_def_map[prelude.module_id].scope.entries().for_each(|(name, res)| {
-                        f(name.clone(), res.def.into());
-                    });
+                    let prelude_def_map = db.crate_def_map(prelude.krate());
+                    prelude_def_map[prelude.id.module_id].scope.entries().for_each(
+                        |(name, res)| {
+                            f(name.clone(), res.def.into());
+                        },
+                    );
                 }
             }
             Scope::GenericParams(gp) => {
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..aec484feb 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -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
diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
new file mode 100644
index 000000000..f22a678eb
--- /dev/null
+++ b/crates/ra_hir_def/Cargo.toml
@@ -0,0 +1,13 @@
+[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" }
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
new file mode 100644
index 000000000..f5dd2ae6f
--- /dev/null
+++ b/crates/ra_hir_def/src/lib.rs
@@ -0,0 +1,14 @@
+use ra_arena::{impl_arena_id, RawId};
+use ra_db::CrateId;
+
+#[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);