26 files changed, 366 insertions, 431 deletions

diff --git a/crates/ra_db/src/input.rs b/crates/ra_db/src/input.rs
index b5d63e820..9825d52cf 100644
--- a/crates/ra_db/src/input.rs
+++ b/crates/ra_db/src/input.rs
@@ -160,6 +160,7 @@ pub trait FilesDatabase: salsa::Database {
     /// Contents of the source root.
     #[salsa::input]
     fn source_root(&self, id: SourceRootId) -> Arc<SourceRoot>;
+    fn source_root_crates(&self, id: SourceRootId) -> Arc<Vec<CrateId>>;
     /// The set of "local" (that is, from the current workspace) roots.
     /// Files in local roots are assumed to change frequently.
     #[salsa::input]
@@ -173,6 +174,17 @@ pub trait FilesDatabase: salsa::Database {
     fn crate_graph(&self) -> Arc<CrateGraph>;
 }
 
+fn source_root_crates(db: &impl FilesDatabase, id: SourceRootId) -> Arc<Vec<CrateId>> {
+    let root = db.source_root(id);
+    let graph = db.crate_graph();
+    let res = root
+        .files
+        .values()
+        .filter_map(|&it| graph.crate_id_for_crate_root(it))
+        .collect::<Vec<_>>();
+    Arc::new(res)
+}
+
 #[cfg(test)]
 mod tests {
     use super::{CrateGraph, FileId, SmolStr};
diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index 32d7e09b9..84759c75a 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -13,7 +13,7 @@ pub use crate::{
     cancellation::Canceled,
     input::{
         FilesDatabase, FileId, CrateId, SourceRoot, SourceRootId, CrateGraph, Dependency,
-        FileTextQuery, FileSourceRootQuery, SourceRootQuery, LocalRootsQuery, LibraryRootsQuery, CrateGraphQuery,
+        FileTextQuery, FileSourceRootQuery, SourceRootQuery, SourceRootCratesQuery, LocalRootsQuery, LibraryRootsQuery, CrateGraphQuery,
         FileRelativePathQuery
     },
     loc2id::LocationIntener,
diff --git a/crates/ra_hir/src/adt.rs b/crates/ra_hir/src/adt.rs
index ab1c428db..4cca09351 100644
--- a/crates/ra_hir/src/adt.rs
+++ b/crates/ra_hir/src/adt.rs
@@ -64,9 +64,9 @@ fn get_def_id(
         ..same_file_loc.source_item_id
     };
     let loc = DefLoc {
+        module: same_file_loc.module,
         kind: expected_kind,
         source_item_id,
-        ..*same_file_loc
     };
     loc.id(db)
 }
diff --git a/crates/ra_hir/src/code_model_api.rs b/crates/ra_hir/src/code_model_api.rs
index 3ff07bd60..f59a60c07 100644
--- a/crates/ra_hir/src/code_model_api.rs
+++ b/crates/ra_hir/src/code_model_api.rs
@@ -14,13 +14,14 @@ use crate::{
     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,
 };
 
 /// 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,
 }
@@ -45,7 +46,6 @@ impl Crate {
 
 #[derive(Debug)]
 pub enum Def {
-    Module(Module),
     Struct(Struct),
     Enum(Enum),
     EnumVariant(EnumVariant),
@@ -57,9 +57,29 @@ pub enum Def {
     Item,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Module {
-    pub(crate) def_id: DefId,
+    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),
+    Def(DefId),
+}
+
+impl Into<ModuleDef> for Module {
+    fn into(self) -> ModuleDef {
+        ModuleDef::Module(self)
+    }
+}
+
+impl Into<ModuleDef> for DefId {
+    fn into(self) -> ModuleDef {
+        ModuleDef::Def(self)
+    }
 }
 
 pub enum ModuleSource {
@@ -149,7 +169,7 @@ 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)
     }
 
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..5d00e905b 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, Def,
     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() {
@@ -164,32 +126,39 @@ 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) => {
-                    // enum variant
-                    let matching_variant = e
-                        .variants(db)
-                        .into_iter()
-                        .find(|(n, _variant)| n == &segment.name);
-
-                    match matching_variant {
-                        Some((_n, variant)) => PerNs::both(variant.def_id(), e.def_id()),
-                        None => PerNs::none(),
+                ModuleDef::Def(def) => {
+                    match def.resolve(db) {
+                        Def::Enum(e) => {
+                            // enum variant
+                            let matching_variant = e
+                                .variants(db)
+                                .into_iter()
+                                .find(|(n, _variant)| n == &segment.name);
+
+                            match matching_variant {
+                                Some((_n, variant)) => {
+                                    PerNs::both(variant.def_id().into(), e.def_id().into())
+                                }
+                                None => PerNs::none(),
+                            }
+                        }
+                        _ => {
+                            // could be an inherent method call in UFCS form
+                            // (`Struct::method`), or some other kind of associated
+                            // item... Which we currently don't handle (TODO)
+                            PerNs::none()
+                        }
                     }
                 }
-                _ => {
-                    // could be an inherent method call in UFCS form
-                    // (`Struct::method`), or some other kind of associated
-                    // item... Which we currently don't handle (TODO)
-                    PerNs::none()
-                }
             };
         }
         curr_per_ns
@@ -199,8 +168,7 @@ 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..0898daa3c 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,15 +1,15 @@
 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,
+    DefId, MacroCallId, Name, HirFileId,
+    SourceFileItems, SourceItemId, Crate, Module, HirInterner,
     query_definitions,
     FnSignature, FnScopes,
     macros::MacroExpansion,
-    module_tree::{ModuleId, ModuleTree},
+    module_tree::ModuleTree,
     nameres::{ItemMap, lower::{LoweredModule, ImportSourceMap}},
     ty::{InferenceResult, Ty, method_resolution::CrateImplBlocks},
     adt::{StructData, EnumData, EnumVariantData},
@@ -56,38 +56,22 @@ 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>;
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 43f0e81f9..99f04e4ef 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -1,11 +1,10 @@
-use ra_db::{SourceRootId, LocationIntener, FileId};
+use ra_db::{LocationIntener, FileId};
 use ra_syntax::{TreeArc, SyntaxNode, SourceFile, AstNode, ast};
 use ra_arena::{Arena, RawId, impl_arena_id};
 
 use crate::{
     HirDatabase, Def, Function, Struct, Enum, EnumVariant, ImplBlock, Crate,
     Module, Trait, Type, Static, Const,
-    module_tree::ModuleId,
 };
 
 #[derive(Debug, Default)]
@@ -110,10 +109,9 @@ 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,
 }
 
@@ -139,14 +137,12 @@ 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) module: Module,
     pub(crate) source_item_id: SourceItemId,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub(crate) enum DefKind {
-    Module,
     Function,
     Struct,
     Enum,
@@ -177,10 +173,6 @@ impl DefId {
     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)
@@ -221,8 +213,7 @@ impl DefId {
 
     /// 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)
+        self.loc(db).module
     }
 
     /// Returns the containing crate.
@@ -232,8 +223,7 @@ impl DefId {
 
     /// 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);
+        let module_impls = db.impls_in_module(self.loc(db).module);
         ImplBlock::containing(module_impls, self)
     }
 }
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
index 551d0d149..ba8b84da2 100644
--- a/crates/ra_hir/src/impl_block.rs
+++ b/crates/ra_hir/src/impl_block.rs
@@ -3,14 +3,12 @@ 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,
+    Function, HirFileId, HirInterner,
     db::HirDatabase,
     type_ref::TypeRef,
-    module_tree::ModuleId,
 };
 
 use crate::code_model_api::{Module, ModuleSource};
@@ -67,13 +65,13 @@ pub struct ImplData {
 impl ImplData {
     pub(crate) fn from_ast(
         db: &impl AsRef<HirInterner>,
+        file_id: HirFileId,
         file_items: &SourceFileItems,
-        module: &Module,
+        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 items = if let Some(item_list) = node.item_list() {
             item_list
                 .impl_items()
@@ -85,13 +83,13 @@ impl ImplData {
                     };
                     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,
+                        file_id,
                         item_id: Some(item_id),
                     };
                     let def_loc = DefLoc {
+                        module,
                         kind,
                         source_item_id,
-                        ..module_loc
                     };
                     let def_id = def_loc.id(db);
                     match item_node.kind() {
@@ -168,6 +166,7 @@ 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
@@ -176,10 +175,11 @@ impl ModuleImplBlocks {
                 .syntax(),
         };
 
-        let source_file_items = db.file_items(file_id.into());
+        let source_file_items = db.file_items(file_id);
 
         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, &source_file_items, 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);
@@ -188,13 +188,8 @@ impl ModuleImplBlocks {
     }
 }
 
-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..a6246a5e9 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -52,7 +52,7 @@ pub use self::{
 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..6f003bd66 100644
--- a/crates/ra_hir/src/nameres/lower.rs
+++ b/crates/ra_hir/src/nameres/lower.rs
@@ -4,14 +4,13 @@ use ra_syntax::{
     SyntaxKind, 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
+    HirFileId, MacroCallLoc, AsName, PerNs, DefKind, DefLoc,
+    ModuleDef, Module,
 };
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -32,7 +31,7 @@ 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 +58,31 @@ 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 +91,7 @@ impl LoweredModule {
                     res.fill(
                         &mut source_map,
                         db,
-                        source_root_id,
-                        module_id,
+                        module,
                         file_id,
                         &mut item_list.items_with_macros(),
                     )
@@ -113,8 +105,7 @@ 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 +114,12 @@ 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, &file_items, 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),
@@ -148,15 +130,7 @@ impl LoweredModule {
                     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, &file_items, item);
                     }
                 }
             }
@@ -167,8 +141,7 @@ 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,
@@ -199,7 +172,7 @@ impl LoweredModule {
             }
         };
         if let Some(name) = name {
-            let def_id = assign_def_id(db, source_root_id, module_id, file_id, file_items, item);
+            let def_id = assign_def_id(db, module, file_id, file_items, item);
             self.declarations.insert(name.as_name(), def_id);
         }
     }
@@ -219,12 +192,11 @@ impl LoweredModule {
 
 fn assign_def_id(
     db: &impl HirDatabase,
-    source_root_id: SourceRootId,
-    module_id: ModuleId,
+    module: Module,
     file_id: HirFileId,
     file_items: &SourceFileItems,
     item: &ast::ModuleItem,
-) -> PerNs<DefId> {
+) -> PerNs<ModuleDef> {
     // 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());
@@ -232,14 +204,13 @@ fn assign_def_id(
         let item_id = file_items.id_of_unchecked(item.syntax());
         let def_loc = DefLoc {
             kind: k,
-            source_root_id,
-            module_id,
+            module,
             source_item_id: SourceItemId {
                 file_id,
                 item_id: Some(item_id),
             },
         };
-        def_loc.id(db)
+        def_loc.id(db).into()
     });
     def_id
 }
@@ -248,7 +219,6 @@ 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),
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..a8ed887b3 100644
--- a/crates/ra_hir/src/query_definitions.rs
+++ b/crates/ra_hir/src/query_definitions.rs
@@ -7,11 +7,11 @@ 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,
+    FnScopes, Module,
     db::HirDatabase,
     nameres::{ItemMap, Resolver},
 };
@@ -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..c3bd31d6b 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -13,7 +13,7 @@ use ra_syntax::{
 };
 
 use crate::{
-    HirDatabase, Function, SourceItemId,
+    HirDatabase, Function, SourceItemId, ModuleDef,
     DefKind, DefLoc, AsName, Module,
 };
 
@@ -84,9 +84,13 @@ 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> {
@@ -110,8 +114,8 @@ pub fn function_from_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_id, _) = module.definition_source(db);
+    let file_id = file_id.into();
     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 {
@@ -119,9 +123,8 @@ pub fn function_from_module(
         item_id: Some(item_id),
     };
     let def_loc = DefLoc {
+        module: module.clone(),
         kind: DefKind::Function,
-        source_root_id: loc.source_root_id,
-        module_id: loc.module_id,
         source_item_id,
     };
     Function::new(def_loc.id(db))
@@ -141,14 +144,17 @@ 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.clone().take_types())
+        .filter_map(|it| match it {
+            ModuleDef::Def(it) => Some(it),
+            _ => None,
+        })
         .filter_map(|it| it.loc(db).source_item_id.file_id.as_macro_call_id())
     {
         if let Some(exp) = db.expand_macro_invocation(macro_call_id) {
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index e690ae158..4c96579ee 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -32,7 +32,7 @@ use rustc_hash::FxHashMap;
 
 use crate::{
     Def, DefId, Module, Function, Struct, StructField, Enum, EnumVariant, Path, Name, ImplBlock,
-    FnSignature, FnScopes,
+    FnSignature, FnScopes, ModuleDef,
     db::HirDatabase,
     type_ref::{TypeRef, Mutability},
     name::KnownName,
@@ -382,8 +382,8 @@ impl Ty {
 
         // Resolve in module (in type namespace)
         let resolved = match module.resolve_path(db, path).take_types() {
-            Some(r) => r,
-            None => return Ty::Unknown,
+            Some(ModuleDef::Def(r)) => r,
+            None | Some(ModuleDef::Module(_)) => return Ty::Unknown,
         };
         let ty = db.type_for_def(resolved);
         let substs = Ty::substs_from_path(db, module, impl_block, generics, path, resolved);
@@ -663,10 +663,6 @@ pub(crate) fn type_for_enum_variant(db: &impl HirDatabase, ev: EnumVariant) -> T
 pub(super) fn type_for_def(db: &impl HirDatabase, def_id: DefId) -> Ty {
     let def = def_id.resolve(db);
     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),
@@ -1063,7 +1059,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         };
 
         // resolve in module
-        let resolved = self.module.resolve_path(self.db, &path).take_values()?;
+        let resolved = match self.module.resolve_path(self.db, &path).take_values()? {
+            ModuleDef::Def(it) => it,
+            ModuleDef::Module(_) => return None,
+        };
         let ty = self.db.type_for_def(resolved);
         let ty = self.insert_type_vars(ty);
         Some(ty)
@@ -1075,7 +1074,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             None => return (Ty::Unknown, None),
         };
         let def_id = match self.module.resolve_path(self.db, &path).take_types() {
-            Some(def_id) => def_id,
+            Some(ModuleDef::Def(def_id)) => def_id,
             _ => return (Ty::Unknown, None),
         };
         // TODO remove the duplication between here and `Ty::from_path`?
@@ -1216,6 +1215,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 .module
                 .resolve_path(self.db, &path)
                 .take_values()
+                .and_then(|module_def| match module_def {
+                    ModuleDef::Def(it) => Some(it),
+                    ModuleDef::Module(_) => None,
+                })
                 .map_or(Ty::Unknown, |resolved| self.db.type_for_def(resolved)),
             Pat::Bind {
                 mode,
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 9f65c5fe1..a5567a78f 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -6,8 +6,6 @@ use std::sync::Arc;
 
 use rustc_hash::FxHashMap;
 
-use ra_db::SourceRootId;
-
 use crate::{
     HirDatabase, DefId, module_tree::ModuleId, Module, Crate, Name, Function,
     impl_block::{ImplId, ImplBlock, ImplItem},
@@ -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)
     }
diff --git a/crates/ra_ide_api/src/completion/complete_path.rs b/crates/ra_ide_api/src/completion/complete_path.rs
index e44b76c4a..0d7942496 100644
--- a/crates/ra_ide_api/src/completion/complete_path.rs
+++ b/crates/ra_ide_api/src/completion/complete_path.rs
@@ -13,8 +13,8 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
         Some(it) => it,
         None => return,
     };
-    match def_id.resolve(ctx.db) {
-        hir::Def::Module(module) => {
+    match def_id {
+        hir::ModuleDef::Module(module) => {
             let module_scope = module.scope(ctx.db);
             for (name, res) in module_scope.entries() {
                 CompletionItem::new(
@@ -26,21 +26,24 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
                 .add_to(acc);
             }
         }
-        hir::Def::Enum(e) => {
-            e.variants(ctx.db)
-                .into_iter()
-                .for_each(|(variant_name, variant)| {
-                    CompletionItem::new(
-                        CompletionKind::Reference,
-                        ctx.source_range(),
-                        variant_name.to_string(),
-                    )
-                    .kind(CompletionItemKind::EnumVariant)
-                    .set_documentation(variant.docs(ctx.db))
-                    .add_to(acc)
-                });
-        }
-        _ => return,
+
+        hir::ModuleDef::Def(def_id) => match def_id.resolve(ctx.db) {
+            hir::Def::Enum(e) => {
+                e.variants(ctx.db)
+                    .into_iter()
+                    .for_each(|(variant_name, variant)| {
+                        CompletionItem::new(
+                            CompletionKind::Reference,
+                            ctx.source_range(),
+                            variant_name.to_string(),
+                        )
+                        .kind(CompletionItemKind::EnumVariant)
+                        .set_documentation(variant.docs(ctx.db))
+                        .add_to(acc)
+                    });
+            }
+            _ => return,
+        },
     };
 }
 
diff --git a/crates/ra_ide_api/src/completion/completion_item.rs b/crates/ra_ide_api/src/completion/completion_item.rs
index 18c151932..5d6718a8d 100644
--- a/crates/ra_ide_api/src/completion/completion_item.rs
+++ b/crates/ra_ide_api/src/completion/completion_item.rs
@@ -1,6 +1,4 @@
-use hir::{Docs, Documentation, PerNs};
-
-use crate::completion::completion_context::CompletionContext;
+use hir::{Docs, Documentation};
 use ra_syntax::{
     ast::{self, AstNode},
     TextRange,
@@ -8,6 +6,8 @@ use ra_syntax::{
 use ra_text_edit::TextEdit;
 use test_utils::tested_by;
 
+use crate::completion::completion_context::CompletionContext;
+
 /// `CompletionItem` describes a single completion variant in the editor pop-up.
 /// It is basically a POD with various properties. To construct a
 /// `CompletionItem`, use `new` method and the `Builder` struct.
@@ -209,41 +209,26 @@ impl Builder {
         ctx: &CompletionContext,
         resolution: &hir::Resolution,
     ) -> Builder {
-        let resolved = resolution.def_id.map(|d| d.resolve(ctx.db));
-        let (kind, docs) = match resolved {
-            PerNs {
-                types: Some(hir::Def::Module(..)),
-                ..
-            } => (CompletionItemKind::Module, None),
-            PerNs {
-                types: Some(hir::Def::Struct(s)),
-                ..
-            } => (CompletionItemKind::Struct, s.docs(ctx.db)),
-            PerNs {
-                types: Some(hir::Def::Enum(e)),
-                ..
-            } => (CompletionItemKind::Enum, e.docs(ctx.db)),
-            PerNs {
-                types: Some(hir::Def::Trait(t)),
-                ..
-            } => (CompletionItemKind::Trait, t.docs(ctx.db)),
-            PerNs {
-                types: Some(hir::Def::Type(t)),
-                ..
-            } => (CompletionItemKind::TypeAlias, t.docs(ctx.db)),
-            PerNs {
-                values: Some(hir::Def::Const(c)),
-                ..
-            } => (CompletionItemKind::Const, c.docs(ctx.db)),
-            PerNs {
-                values: Some(hir::Def::Static(s)),
-                ..
-            } => (CompletionItemKind::Static, s.docs(ctx.db)),
-            PerNs {
-                values: Some(hir::Def::Function(function)),
-                ..
-            } => return self.from_function(ctx, function),
-            _ => return self,
+        let def = resolution
+            .def_id
+            .take_types()
+            .or(resolution.def_id.take_values());
+        let def = match def {
+            None => return self,
+            Some(it) => it,
+        };
+        let (kind, docs) = match def {
+            hir::ModuleDef::Module(_) => (CompletionItemKind::Module, None),
+            hir::ModuleDef::Def(def_id) => match def_id.resolve(ctx.db) {
+                hir::Def::Struct(it) => (CompletionItemKind::Struct, it.docs(ctx.db)),
+                hir::Def::Enum(it) => (CompletionItemKind::Enum, it.docs(ctx.db)),
+                hir::Def::Trait(it) => (CompletionItemKind::Trait, it.docs(ctx.db)),
+                hir::Def::Type(it) => (CompletionItemKind::TypeAlias, it.docs(ctx.db)),
+                hir::Def::Const(it) => (CompletionItemKind::Const, it.docs(ctx.db)),
+                hir::Def::Static(it) => (CompletionItemKind::Static, it.docs(ctx.db)),
+                hir::Def::Function(function) => return self.from_function(ctx, function),
+                _ => return self,
+            },
         };
         self.kind = Some(kind);
         self.documentation = docs;
diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index ba0eb1cb8..bff6b7237 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -72,6 +72,7 @@ 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_ide_api/src/goto_definition.rs b/crates/ra_ide_api/src/goto_definition.rs
index b1becca03..323bb1cc1 100644
--- a/crates/ra_ide_api/src/goto_definition.rs
+++ b/crates/ra_ide_api/src/goto_definition.rs
@@ -67,7 +67,7 @@ pub(crate) fn reference_definition(
                 .node_expr(expr)
                 .and_then(|it| infer_result.method_resolution(it))
             {
-                if let Some(target) = NavigationTarget::from_def(db, def_id.resolve(db)) {
+                if let Some(target) = NavigationTarget::from_def(db, hir::ModuleDef::Def(def_id)) {
                     return Exact(target);
                 }
             };
@@ -84,7 +84,7 @@ pub(crate) fn reference_definition(
         {
             let resolved = module.resolve_path(db, &path);
             if let Some(def_id) = resolved.take_types().or(resolved.take_values()) {
-                if let Some(target) = NavigationTarget::from_def(db, def_id.resolve(db)) {
+                if let Some(target) = NavigationTarget::from_def(db, def_id) {
                     return Exact(target);
                 }
             }
diff --git a/crates/ra_ide_api/src/navigation_target.rs b/crates/ra_ide_api/src/navigation_target.rs
index 21c15c0c0..1eb177665 100644
--- a/crates/ra_ide_api/src/navigation_target.rs
+++ b/crates/ra_ide_api/src/navigation_target.rs
@@ -97,7 +97,17 @@ impl NavigationTarget {
     }
 
     // TODO once Def::Item is gone, this should be able to always return a NavigationTarget
-    pub(crate) fn from_def(db: &RootDatabase, def: Def) -> Option<NavigationTarget> {
+    pub(crate) fn from_def(
+        db: &RootDatabase,
+        module_def: hir::ModuleDef,
+    ) -> Option<NavigationTarget> {
+        let def = match module_def {
+            hir::ModuleDef::Def(def_id) => def_id.resolve(db),
+            hir::ModuleDef::Module(module) => {
+                return Some(NavigationTarget::from_module(db, module));
+            }
+        };
+
         let res = match def {
             Def::Struct(s) => {
                 let (file_id, node) = s.source(db);
@@ -131,7 +141,6 @@ impl NavigationTarget {
                 let (file_id, node) = f.source(db);
                 NavigationTarget::from_named(file_id.original_file(db), &*node)
             }
-            Def::Module(m) => NavigationTarget::from_module(db, m),
             Def::Item => return None,
         };
         Some(res)
diff --git a/crates/ra_ide_api/src/rename.rs b/crates/ra_ide_api/src/rename.rs
index 53dc273c6..5b767addd 100644
--- a/crates/ra_ide_api/src/rename.rs
+++ b/crates/ra_ide_api/src/rename.rs
@@ -57,7 +57,6 @@ fn rename_mod(
 ) -> Option<SourceChange> {
     let mut source_file_edits = Vec::new();
     let mut file_system_edits = Vec::new();
-
     if let Some(module) = module_from_declaration(db, position.file_id, &ast_module) {
         let (file_id, module_source) = module.definition_source(db);
         match module_source {
@@ -223,11 +222,15 @@ mod tests {
     fn test_rename_mod() {
         let (analysis, position) = analysis_and_position(
             "
-        //- /bar.rs
-        mod fo<|>o;
-        //- /bar/foo.rs
-        // emtpy
-    ",
+            //- /lib.rs
+            mod bar;
+
+            //- /bar.rs
+            mod foo<|>;
+
+            //- /bar/foo.rs
+            // emtpy
+            ",
         );
         let new_name = "foo2";
         let source_change = analysis.rename(position, new_name).unwrap();
@@ -238,11 +241,11 @@ mod tests {
     fn test_rename_mod_in_dir() {
         let (analysis, position) = analysis_and_position(
             "
-        //- /lib.rs
-        mod fo<|>o;
-        //- /foo/mod.rs
-        // emtpy
-    ",
+            //- /lib.rs
+            mod fo<|>o;
+            //- /foo/mod.rs
+            // emtpy
+            ",
         );
         let new_name = "foo2";
         let source_change = analysis.rename(position, new_name).unwrap();
diff --git a/crates/ra_ide_api/src/snapshots/tests__rename_mod.snap b/crates/ra_ide_api/src/snapshots/tests__rename_mod.snap
index 3267d1ac5..890426db7 100644
--- a/crates/ra_ide_api/src/snapshots/tests__rename_mod.snap
+++ b/crates/ra_ide_api/src/snapshots/tests__rename_mod.snap
@@ -1,8 +1,8 @@
 ---
-created: "2019-01-22T14:45:00.975229300+00:00"
-creator: insta@0.4.0
+created: "2019-01-24T08:39:53.759318522+00:00"
+creator: insta@0.5.2
 expression: "&source_change"
-source: "crates\\ra_ide_api\\src\\rename.rs"
+source: crates/ra_ide_api/src/rename.rs
 ---
 Some(
     SourceChange {
@@ -10,7 +10,7 @@ Some(
         source_file_edits: [
             SourceFileEdit {
                 file_id: FileId(
-                    1
+                    2
                 ),
                 edit: TextEdit {
                     atoms: [
@@ -25,7 +25,7 @@ Some(
         file_system_edits: [
             MoveFile {
                 src: FileId(
-                    2
+                    3
                 ),
                 dst_source_root: SourceRootId(
                     0