diff --git a/crates/ra_hir/src/code_model_impl/module.rs b/crates/ra_hir/src/code_model_impl/module.rs
index 480ec27bf53..418d59c91ed 100644
--- a/crates/ra_hir/src/code_model_impl/module.rs
+++ b/crates/ra_hir/src/code_model_impl/module.rs
@@ -25,9 +25,10 @@ pub(crate) fn name_impl(&self, db: &impl HirDatabase) -> Option<Name> {
 
     pub(crate) fn definition_source_impl(&self, db: &impl HirDatabase) -> (FileId, ModuleSource) {
         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();
+        let file_id = self.module_id.file_id(&module_tree);
+        let decl_id = self.module_id.decl_id(&module_tree);
+        let module_source = ModuleSource::new(db, file_id, decl_id);
+        let file_id = file_id.as_original_file();
         (file_id, module_source)
     }
 
@@ -39,8 +40,7 @@ pub(crate) fn declaration_source_impl(
         let link = self.module_id.parent_link(&module_tree)?;
         let file_id = link
             .owner(&module_tree)
-            .source(&module_tree)
-            .file_id
+            .file_id(&module_tree)
             .as_original_file();
         let src = link.source(&module_tree, db);
         Some((file_id, src))
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 5df4bd4a152..3f76b769dd2 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -16,6 +16,7 @@
     adt::{StructData, EnumData},
     impl_block::ModuleImplBlocks,
     generics::{GenericParams, GenericDef},
+    ids::SourceFileItemId,
 };
 
 #[salsa::query_group(HirDatabaseStorage)]
@@ -51,7 +52,11 @@ pub trait HirDatabase: SourceDatabase + AsRef<HirInterner> {
     fn file_item(&self, source_item_id: SourceItemId) -> TreeArc<SyntaxNode>;
 
     #[salsa::invoke(crate::module_tree::Submodule::submodules_query)]
-    fn submodules(&self, source: SourceItemId) -> Arc<Vec<crate::module_tree::Submodule>>;
+    fn submodules(
+        &self,
+        file_id: HirFileId,
+        delc_id: Option<SourceFileItemId>,
+    ) -> Arc<Vec<crate::module_tree::Submodule>>;
 
     #[salsa::invoke(crate::nameres::lower::LoweredModule::lower_module_query)]
     fn lower_module(&self, module: Module) -> (Arc<LoweredModule>, Arc<ImportSourceMap>);
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 015d640e36a..0e4dc62614d 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -203,7 +203,7 @@ fn from_ast(ctx: LocationCtx<&impl HirDatabase>, ast: &N) -> Self {
         let items = ctx.db.file_items(ctx.file_id);
         let raw = SourceItemId {
             file_id: ctx.file_id,
-            item_id: Some(items.id_of(ctx.file_id, ast.syntax())),
+            item_id: items.id_of(ctx.file_id, ast.syntax()),
         };
         let loc = ItemLoc {
             module: ctx.module,
@@ -301,8 +301,7 @@ fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::TypeDef>, S
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct SourceItemId {
     pub(crate) file_id: HirFileId,
-    /// None for the whole file.
-    pub(crate) item_id: Option<SourceFileItemId>,
+    pub(crate) item_id: SourceFileItemId,
 }
 
 /// Maps items' `SyntaxNode`s to `SourceFileItemId`s and back.
diff --git a/crates/ra_hir/src/module_tree.rs b/crates/ra_hir/src/module_tree.rs
index d5ad9decbf3..d1dc3fa4b70 100644
--- a/crates/ra_hir/src/module_tree.rs
+++ b/crates/ra_hir/src/module_tree.rs
@@ -11,21 +11,28 @@
 use ra_arena::{Arena, RawId, impl_arena_id};
 use test_utils::tested_by;
 
-use crate::{Name, AsName, HirDatabase, SourceItemId, HirFileId, Problem, SourceFileItems, ModuleSource};
+use crate::{
+    Name, AsName, HirDatabase, SourceItemId, HirFileId, Problem, SourceFileItems, ModuleSource,
+    ids::SourceFileItemId,
+};
 
 impl ModuleSource {
-    pub(crate) fn from_source_item_id(
+    pub(crate) fn new(
         db: &impl HirDatabase,
-        source_item_id: SourceItemId,
+        file_id: HirFileId,
+        decl_id: Option<SourceFileItemId>,
     ) -> ModuleSource {
-        let module_syntax = db.file_item(source_item_id);
-        if let Some(source_file) = ast::SourceFile::cast(&module_syntax) {
-            ModuleSource::SourceFile(source_file.to_owned())
-        } else if let Some(module) = ast::Module::cast(&module_syntax) {
-            assert!(module.item_list().is_some(), "expected inline module");
-            ModuleSource::Module(module.to_owned())
-        } else {
-            panic!("expected file or inline module")
+        match decl_id {
+            Some(item_id) => {
+                let module = db.file_item(SourceItemId { file_id, item_id });
+                let module = ast::Module::cast(&*module).unwrap();
+                assert!(module.item_list().is_some(), "expected inline module");
+                ModuleSource::Module(module.to_owned())
+            }
+            None => {
+                let source_file = db.hir_parse(file_id);
+                ModuleSource::SourceFile(source_file)
+            }
         }
     }
 }
@@ -34,18 +41,18 @@ pub(crate) fn from_source_item_id(
 pub struct Submodule {
     name: Name,
     is_declaration: bool,
-    source: SourceItemId,
+    decl_id: SourceFileItemId,
 }
 
 impl Submodule {
     pub(crate) fn submodules_query(
         db: &impl HirDatabase,
-        source: SourceItemId,
+        file_id: HirFileId,
+        decl_id: Option<SourceFileItemId>,
     ) -> Arc<Vec<Submodule>> {
         db.check_canceled();
-        let file_id = source.file_id;
         let file_items = db.file_items(file_id);
-        let module_source = ModuleSource::from_source_item_id(db, source);
+        let module_source = ModuleSource::new(db, file_id, decl_id);
         let submodules = match module_source {
             ModuleSource::SourceFile(source_file) => {
                 collect_submodules(file_id, &file_items, &*source_file)
@@ -54,6 +61,7 @@ pub(crate) fn submodules_query(
                 collect_submodules(file_id, &file_items, module.item_list().unwrap())
             }
         };
+
         return Arc::new(submodules);
 
         fn collect_submodules(
@@ -75,10 +83,7 @@ fn collect_submodules(
                     let sub = Submodule {
                         name,
                         is_declaration: module.has_semi(),
-                        source: SourceItemId {
-                            file_id,
-                            item_id: Some(file_items.id_of(file_id, module.syntax())),
-                        },
+                        decl_id: file_items.id_of(file_id, module.syntax()),
                     };
                     Some(sub)
                 })
@@ -110,7 +115,9 @@ pub struct ModuleTree {
 
 #[derive(Debug, PartialEq, Eq, Hash)]
 pub struct ModuleData {
-    source: SourceItemId,
+    file_id: HirFileId,
+    /// Points to `ast::Module`, `None` for the whole file.
+    decl_id: Option<SourceFileItemId>,
     parent: Option<LinkId>,
     children: Vec<LinkId>,
 }
@@ -136,8 +143,15 @@ pub(crate) fn modules<'a>(&'a self) -> impl Iterator<Item = ModuleId> + 'a {
         self.mods.iter().map(|(id, _)| id)
     }
 
-    pub(crate) fn find_module_by_source(&self, source: SourceItemId) -> Option<ModuleId> {
-        let (res, _) = self.mods.iter().find(|(_, m)| m.source == source)?;
+    pub(crate) fn find_module_by_source(
+        &self,
+        file_id: HirFileId,
+        decl_id: Option<SourceFileItemId>,
+    ) -> Option<ModuleId> {
+        let (res, _) = self
+            .mods
+            .iter()
+            .find(|(_, m)| (m.file_id, m.decl_id) == (file_id, decl_id))?;
         Some(res)
     }
 
@@ -147,11 +161,7 @@ fn init_crate(&mut self, db: &impl HirDatabase, crate_id: CrateId) {
         let source_root_id = db.file_source_root(file_id);
 
         let source_root = db.source_root(source_root_id);
-        let source = SourceItemId {
-            file_id: file_id.into(),
-            item_id: None,
-        };
-        self.init_subtree(db, &source_root, None, source);
+        self.init_subtree(db, &source_root, None, file_id.into(), None);
     }
 
     fn init_subtree(
@@ -159,16 +169,21 @@ fn init_subtree(
         db: &impl HirDatabase,
         source_root: &SourceRoot,
         parent: Option<LinkId>,
-        source: SourceItemId,
+        file_id: HirFileId,
+        decl_id: Option<SourceFileItemId>,
     ) -> ModuleId {
         let id = self.alloc_mod(ModuleData {
-            source,
+            file_id,
+            decl_id,
             parent,
             children: Vec::new(),
         });
-        for sub in db.submodules(source).iter() {
+        for sub in db.submodules(file_id, decl_id).iter() {
             let link = self.alloc_link(LinkData {
-                source: sub.source,
+                source: SourceItemId {
+                    file_id,
+                    item_id: sub.decl_id,
+                },
                 name: sub.name.clone(),
                 owner: id,
                 points_to: Vec::new(),
@@ -176,24 +191,17 @@ fn init_subtree(
             });
 
             let (points_to, problem) = if sub.is_declaration {
-                let (points_to, problem) = resolve_submodule(db, source.file_id, &sub.name);
+                let (points_to, problem) = resolve_submodule(db, file_id, &sub.name);
                 let points_to = points_to
                     .into_iter()
                     .map(|file_id| {
-                        self.init_subtree(
-                            db,
-                            source_root,
-                            Some(link),
-                            SourceItemId {
-                                file_id: file_id.into(),
-                                item_id: None,
-                            },
-                        )
+                        self.init_subtree(db, source_root, Some(link), file_id.into(), None)
                     })
                     .collect::<Vec<_>>();
                 (points_to, problem)
             } else {
-                let points_to = self.init_subtree(db, source_root, Some(link), sub.source);
+                let points_to =
+                    self.init_subtree(db, source_root, Some(link), file_id, Some(sub.decl_id));
                 (vec![points_to], None)
             };
 
@@ -216,8 +224,11 @@ fn alloc_link(&mut self, data: LinkData) -> LinkId {
 }
 
 impl ModuleId {
-    pub(crate) fn source(self, tree: &ModuleTree) -> SourceItemId {
-        tree.mods[self].source
+    pub(crate) fn file_id(self, tree: &ModuleTree) -> HirFileId {
+        tree.mods[self].file_id
+    }
+    pub(crate) fn decl_id(self, tree: &ModuleTree) -> Option<SourceFileItemId> {
+        tree.mods[self].decl_id
     }
     pub(crate) fn parent_link(self, tree: &ModuleTree) -> Option<LinkId> {
         tree.mods[self].parent
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 5193900e018..97ce6c946d4 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -215,7 +215,7 @@ fn populate_module(&mut self, module_id: ModuleId, input: Arc<LoweredModule>) {
         // Populate extern crates prelude
         {
             let root_id = module_id.crate_root(&self.module_tree);
-            let file_id = root_id.source(&self.module_tree).file_id;
+            let file_id = root_id.file_id(&self.module_tree);
             let crate_graph = self.db.crate_graph();
             if let Some(crate_id) = crate_graph.crate_id_for_crate_root(file_id.as_original_file())
             {
diff --git a/crates/ra_hir/src/nameres/lower.rs b/crates/ra_hir/src/nameres/lower.rs
index 1d77548f385..8df11a5f419 100644
--- a/crates/ra_hir/src/nameres/lower.rs
+++ b/crates/ra_hir/src/nameres/lower.rs
@@ -121,10 +121,7 @@ fn fill(
                     let item_id = file_items.id_of_unchecked(macro_call.syntax());
                     let loc = MacroCallLoc {
                         module,
-                        source_item_id: SourceItemId {
-                            file_id,
-                            item_id: Some(item_id),
-                        },
+                        source_item_id: SourceItemId { file_id, item_id },
                     };
                     let id = loc.id(db);
                     let file_id = HirFileId::from(id);
diff --git a/crates/ra_hir/src/query_definitions.rs b/crates/ra_hir/src/query_definitions.rs
index 380c0640478..bf9ac0dfb42 100644
--- a/crates/ra_hir/src/query_definitions.rs
+++ b/crates/ra_hir/src/query_definitions.rs
@@ -4,9 +4,7 @@
 };
 
 use rustc_hash::FxHashMap;
-use ra_syntax::{
-    AstNode, SyntaxNode, TreeArc,
-};
+use ra_syntax::{SyntaxNode, TreeArc};
 use ra_db::{CrateId};
 
 use crate::{
@@ -33,12 +31,9 @@ pub(super) fn file_item(
     source_item_id: SourceItemId,
 ) -> TreeArc<SyntaxNode> {
     let source_file = db.hir_parse(source_item_id.file_id);
-    match source_item_id.item_id {
-        Some(id) => db.file_items(source_item_id.file_id)[id]
-            .to_node(&source_file)
-            .to_owned(),
-        None => source_file.syntax().to_owned(),
-    }
+    db.file_items(source_item_id.file_id)[source_item_id.item_id]
+        .to_node(&source_file)
+        .to_owned()
 }
 
 pub(super) fn item_map(db: &impl HirDatabase, crate_id: CrateId) -> Arc<ItemMap> {
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index c0b3f1cd481..f523f064760 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -13,18 +13,14 @@
 };
 
 use crate::{
-    HirDatabase, Function, SourceItemId, ModuleDef,
-    AsName, Module,
-    ids::LocationCtx,
+    HirDatabase, Function, ModuleDef,
+    AsName, Module, HirFileId,
+    ids::{LocationCtx, SourceFileItemId},
 };
 
 /// Locates the module by `FileId`. Picks topmost module in the file.
 pub fn module_from_file_id(db: &impl HirDatabase, file_id: FileId) -> Option<Module> {
-    let module_source = SourceItemId {
-        file_id: file_id.into(),
-        item_id: None,
-    };
-    module_from_source(db, module_source)
+    module_from_source(db, file_id.into(), None)
 }
 
 /// Locates the child module by `mod child;` declaration.
@@ -59,11 +55,7 @@ fn module_from_inline(
     let file_id = file_id.into();
     let file_items = db.file_items(file_id);
     let item_id = file_items.id_of(file_id, module.syntax());
-    let source = SourceItemId {
-        file_id,
-        item_id: Some(item_id),
-    };
-    module_from_source(db, source)
+    module_from_source(db, file_id, Some(item_id))
 }
 
 /// Locates the module by child syntax element within the module
@@ -83,13 +75,17 @@ 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());
+fn module_from_source(
+    db: &impl HirDatabase,
+    file_id: HirFileId,
+    decl_id: Option<SourceFileItemId>,
+) -> Option<Module> {
+    let source_root_id = db.file_source_root(file_id.as_original_file());
     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)?;
+            let module_id = module_tree.find_module_by_source(file_id, decl_id)?;
             Some(Module { krate, module_id })
         })
 }