65 files changed, 1278 insertions, 519 deletions

diff --git a/crates/ra_db/Cargo.toml b/crates/ra_db/Cargo.toml
index 3568da905..9aa77f72e 100644
--- a/crates/ra_db/Cargo.toml
+++ b/crates/ra_db/Cargo.toml
@@ -6,9 +6,10 @@ authors = ["Aleksey Kladov <[email protected]>"]
 
 [dependencies]
 relative-path = "0.4.0"
-salsa = "0.10.0-alpha3"
+salsa = "0.10.0-alpha4"
 rustc-hash = "1.0"
 parking_lot = "0.7.0"
+
 ra_arena = { path = "../ra_arena" }
 ra_syntax = { path = "../ra_syntax" }
 test_utils = { path = "../test_utils" }
diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index 7e13f70bc..6e17f33f0 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -20,7 +20,7 @@ pub use crate::{
     loc2id::LocationIntener,
 };
 
-pub trait BaseDatabase: salsa::Database + panic::RefUnwindSafe {
+pub trait CheckCanceled: salsa::Database + panic::RefUnwindSafe {
     /// Aborts current query if there are pending changes.
     ///
     /// rust-analyzer needs to be able to answer semantic questions about the
@@ -63,11 +63,15 @@ pub struct FileRange {
     pub range: TextRange,
 }
 
-#[salsa::query_group]
-pub trait FilesDatabase: salsa::Database {
+/// Database which stores all significant input facts: source code and project
+/// model. Everything else in rust-analyzer is derived from these queries.
+#[salsa::query_group(SourceDatabaseStorage)]
+pub trait SourceDatabase: salsa::Database + CheckCanceled {
     /// Text of the file.
     #[salsa::input]
     fn file_text(&self, file_id: FileId) -> Arc<String>;
+    // Parses the file into the syntax tree.
+    fn parse(&self, file_id: FileId) -> TreeArc<SourceFile>;
     /// Path to a file, relative to the root of its source root.
     #[salsa::input]
     fn file_relative_path(&self, file_id: FileId) -> RelativePathBuf;
@@ -78,20 +82,12 @@ pub trait FilesDatabase: salsa::Database {
     #[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]
-    fn local_roots(&self) -> Arc<Vec<SourceRootId>>;
-    /// The set of roots for crates.io libraries.
-    /// Files in libraries are assumed to never change.
-    #[salsa::input]
-    fn library_roots(&self) -> Arc<Vec<SourceRootId>>;
     /// The crate graph.
     #[salsa::input]
     fn crate_graph(&self) -> Arc<CrateGraph>;
 }
 
-fn source_root_crates(db: &impl FilesDatabase, id: SourceRootId) -> Arc<Vec<CrateId>> {
+fn source_root_crates(db: &impl SourceDatabase, id: SourceRootId) -> Arc<Vec<CrateId>> {
     let root = db.source_root(id);
     let graph = db.crate_graph();
     let res = root
@@ -102,12 +98,7 @@ fn source_root_crates(db: &impl FilesDatabase, id: SourceRootId) -> Arc<Vec<Crat
     Arc::new(res)
 }
 
-#[salsa::query_group]
-pub trait SyntaxDatabase: FilesDatabase + BaseDatabase {
-    fn source_file(&self, file_id: FileId) -> TreeArc<SourceFile>;
-}
-
-fn source_file(db: &impl SyntaxDatabase, file_id: FileId) -> TreeArc<SourceFile> {
+fn parse(db: &impl SourceDatabase, file_id: FileId) -> TreeArc<SourceFile> {
     let text = db.file_text(file_id);
     SourceFile::parse(&*text)
 }
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index 3d802ade4..57a4b155b 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -12,7 +12,6 @@ rustc-hash = "1.0"
 parking_lot = "0.7.0"
 ena = "0.11"
 join_to_string = "0.1.3"
-salsa = "0.10.0-alpha3"
 
 ra_syntax = { path = "../ra_syntax" }
 ra_arena = { path = "../ra_arena" }
diff --git a/crates/ra_hir/src/adt.rs b/crates/ra_hir/src/adt.rs
index ec6a10353..22bbad964 100644
--- a/crates/ra_hir/src/adt.rs
+++ b/crates/ra_hir/src/adt.rs
@@ -11,7 +11,7 @@ use ra_syntax::{
 
 use crate::{
     Name, AsName, Struct, Enum, EnumVariant, Crate,
-    HirDatabase, HirFileId,
+    HirDatabase, HirFileId, StructField, FieldSource,
     type_ref::TypeRef,
 };
 
@@ -150,7 +150,7 @@ impl VariantData {
 impl VariantData {
     fn new(flavor: StructFlavor) -> Self {
         let inner = match flavor {
-            StructFlavor::Tuple(fl) => {
+            ast::StructFlavor::Tuple(fl) => {
                 let fields = fl
                     .fields()
                     .enumerate()
@@ -161,7 +161,7 @@ impl VariantData {
                     .collect();
                 VariantDataInner::Tuple(fields)
             }
-            StructFlavor::Named(fl) => {
+            ast::StructFlavor::Named(fl) => {
                 let fields = fl
                     .fields()
                     .map(|fd| StructFieldData {
@@ -171,8 +171,70 @@ impl VariantData {
                     .collect();
                 VariantDataInner::Struct(fields)
             }
-            StructFlavor::Unit => VariantDataInner::Unit,
+            ast::StructFlavor::Unit => VariantDataInner::Unit,
         };
         VariantData(inner)
     }
 }
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum VariantDef {
+    Struct(Struct),
+    EnumVariant(EnumVariant),
+}
+impl_froms!(VariantDef: Struct, EnumVariant);
+
+impl VariantDef {
+    pub(crate) fn field(self, db: &impl HirDatabase, name: &Name) -> Option<StructField> {
+        match self {
+            VariantDef::Struct(it) => it.field(db, name),
+            VariantDef::EnumVariant(it) => it.field(db, name),
+        }
+    }
+    pub(crate) fn variant_data(self, db: &impl HirDatabase) -> Arc<VariantData> {
+        match self {
+            VariantDef::Struct(it) => it.variant_data(db),
+            VariantDef::EnumVariant(it) => it.variant_data(db),
+        }
+    }
+}
+
+impl StructField {
+    pub(crate) fn source_impl(&self, db: &impl HirDatabase) -> (HirFileId, FieldSource) {
+        let var_data = self.parent.variant_data(db);
+        let fields = var_data.fields().unwrap();
+        let ss;
+        let es;
+        let (file_id, struct_flavor) = match self.parent {
+            VariantDef::Struct(s) => {
+                let (file_id, source) = s.source(db);
+                ss = source;
+                (file_id, ss.flavor())
+            }
+            VariantDef::EnumVariant(e) => {
+                let (file_id, source) = e.source(db);
+                es = source;
+                (file_id, es.flavor())
+            }
+        };
+
+        let field_sources = match struct_flavor {
+            ast::StructFlavor::Tuple(fl) => fl
+                .fields()
+                .map(|it| FieldSource::Pos(it.to_owned()))
+                .collect(),
+            ast::StructFlavor::Named(fl) => fl
+                .fields()
+                .map(|it| FieldSource::Named(it.to_owned()))
+                .collect(),
+            ast::StructFlavor::Unit => Vec::new(),
+        };
+        let field = field_sources
+            .into_iter()
+            .zip(fields.iter())
+            .find(|(_syntax, (id, _))| *id == self.id)
+            .unwrap()
+            .0;
+        (file_id, field)
+    }
+}
diff --git a/crates/ra_hir/src/code_model_api.rs b/crates/ra_hir/src/code_model_api.rs
index 118562984..191104890 100644
--- a/crates/ra_hir/src/code_model_api.rs
+++ b/crates/ra_hir/src/code_model_api.rs
@@ -10,8 +10,8 @@ use crate::{
     nameres::{ModuleScope, lower::ImportId},
     db::HirDatabase,
     expr::BodySyntaxMapping,
-    ty::{InferenceResult, VariantDef},
-    adt::{EnumVariantId, StructFieldId},
+    ty::InferenceResult,
+    adt::{EnumVariantId, StructFieldId, VariantDef},
     generics::GenericParams,
     docs::{Documentation, Docs, docs_from_ast},
     module_tree::ModuleId,
@@ -177,12 +177,25 @@ impl Module {
     }
 }
 
+impl Docs for Module {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        self.declaration_source(db)
+            .and_then(|it| docs_from_ast(&*it.1))
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct StructField {
-    parent: VariantDef,
+    pub(crate) parent: VariantDef,
     pub(crate) id: StructFieldId,
 }
 
+#[derive(Debug)]
+pub enum FieldSource {
+    Named(TreeArc<ast::NamedFieldDef>),
+    Pos(TreeArc<ast::PosFieldDef>),
+}
+
 impl StructField {
     pub fn name(&self, db: &impl HirDatabase) -> Name {
         self.parent.variant_data(db).fields().unwrap()[self.id]
@@ -190,6 +203,10 @@ impl StructField {
             .clone()
     }
 
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, FieldSource) {
+        self.source_impl(db)
+    }
+
     pub fn ty(&self, db: &impl HirDatabase) -> Ty {
         db.type_for_field(*self)
     }
@@ -199,6 +216,15 @@ impl StructField {
     }
 }
 
+impl Docs for StructField {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        match self.source(db).1 {
+            FieldSource::Named(named) => docs_from_ast(&*named),
+            FieldSource::Pos(..) => return None,
+        }
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Struct {
     pub(crate) id: StructId,
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 3c82262a2..5df4bd4a1 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 use ra_syntax::{SyntaxNode, TreeArc, SourceFile};
-use ra_db::{SyntaxDatabase, CrateId, salsa};
+use ra_db::{SourceDatabase, CrateId, salsa};
 
 use crate::{
     MacroCallId, HirFileId,
@@ -18,10 +18,10 @@ use crate::{
     generics::{GenericParams, GenericDef},
 };
 
-#[salsa::query_group]
-pub trait HirDatabase: SyntaxDatabase + AsRef<HirInterner> {
-    #[salsa::invoke(HirFileId::hir_source_file)]
-    fn hir_source_file(&self, file_id: HirFileId) -> TreeArc<SourceFile>;
+#[salsa::query_group(HirDatabaseStorage)]
+pub trait HirDatabase: SourceDatabase + AsRef<HirInterner> {
+    #[salsa::invoke(HirFileId::hir_parse)]
+    fn hir_parse(&self, file_id: HirFileId) -> TreeArc<SourceFile>;
 
     #[salsa::invoke(crate::macros::expand_macro_invocation)]
     fn expand_macro_invocation(&self, invoc: MacroCallId) -> Option<Arc<MacroExpansion>>;
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 5272656ec..7dd4b540e 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -86,12 +86,9 @@ impl HirFileId {
         }
     }
 
-    pub(crate) fn hir_source_file(
-        db: &impl HirDatabase,
-        file_id: HirFileId,
-    ) -> TreeArc<SourceFile> {
+    pub(crate) fn hir_parse(db: &impl HirDatabase, file_id: HirFileId) -> TreeArc<SourceFile> {
         match file_id.0 {
-            HirFileIdRepr::File(file_id) => db.source_file(file_id),
+            HirFileIdRepr::File(file_id) => db.parse(file_id),
             HirFileIdRepr::Macro(m) => {
                 if let Some(exp) = db.expand_macro_invocation(m) {
                     return exp.file();
@@ -370,7 +367,7 @@ impl SourceFileItems {
             self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(),
         );
     }
-    pub fn id_of_source_file(&self) -> SourceFileItemId {
+    pub fn id_of_parse(&self) -> SourceFileItemId {
         let (id, _syntax) = self.arena.iter().next().unwrap();
         id
     }
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 596f9c38c..eaf8565ee 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -68,7 +68,7 @@ pub use self::code_model_api::{
     Module, ModuleDef, ModuleSource, Problem,
     Struct, Enum, EnumVariant,
     Function, FnSignature, ScopeEntryWithSyntax,
-    StructField,
+    StructField, FieldSource,
     Static, Const,
     Trait, Type,
 };
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 36b174cd6..7da15eca0 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -2,7 +2,7 @@ use std::{sync::Arc, panic};
 
 use parking_lot::Mutex;
 use ra_db::{
-    BaseDatabase, FilePosition, FileId, CrateGraph, SourceRoot, SourceRootId, FilesDatabase,
+    CheckCanceled, FilePosition, FileId, CrateGraph, SourceRoot, SourceRootId, SourceDatabase, salsa,
 };
 use relative_path::RelativePathBuf;
 use test_utils::{parse_fixture, CURSOR_MARKER, extract_offset};
@@ -11,7 +11,7 @@ use crate::{db, HirInterner};
 
 pub const WORKSPACE: SourceRootId = SourceRootId(0);
 
-#[salsa::database(ra_db::FilesDatabase, ra_db::SyntaxDatabase, db::HirDatabase)]
+#[salsa::database(ra_db::SourceDatabaseStorage, db::HirDatabaseStorage)]
 #[derive(Debug)]
 pub(crate) struct MockDatabase {
     events: Mutex<Option<Vec<salsa::Event<MockDatabase>>>>,
@@ -140,8 +140,6 @@ impl Default for MockDatabase {
             file_counter: 0,
         };
         db.set_crate_graph(Default::default());
-        db.set_local_roots(Default::default());
-        db.set_library_roots(Default::default());
         db
     }
 }
@@ -157,7 +155,7 @@ impl salsa::ParallelDatabase for MockDatabase {
     }
 }
 
-impl BaseDatabase for MockDatabase {}
+impl CheckCanceled for MockDatabase {}
 
 impl AsRef<HirInterner> for MockDatabase {
     fn as_ref(&self) -> &HirInterner {
diff --git a/crates/ra_hir/src/module_tree.rs b/crates/ra_hir/src/module_tree.rs
index c00834c4c..d5ad9decb 100644
--- a/crates/ra_hir/src/module_tree.rs
+++ b/crates/ra_hir/src/module_tree.rs
@@ -1,6 +1,5 @@
 use std::sync::Arc;
 
-use rustc_hash::{FxHashMap, FxHashSet};
 use arrayvec::ArrayVec;
 use relative_path::RelativePathBuf;
 use ra_db::{FileId, SourceRoot, CrateId};
@@ -147,28 +146,21 @@ impl ModuleTree {
         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_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);
+        self.init_subtree(db, &source_root, None, source);
     }
 
     fn init_subtree(
         &mut self,
         db: &impl HirDatabase,
         source_root: &SourceRoot,
-        visited: &mut FxHashSet<SourceItemId>,
-        roots: &mut FxHashMap<FileId, ModuleId>,
         parent: Option<LinkId>,
         source: SourceItemId,
     ) -> ModuleId {
-        visited.insert(source);
         let id = self.alloc_mod(ModuleData {
             source,
             parent,
@@ -187,28 +179,21 @@ impl ModuleTree {
                 let (points_to, problem) = resolve_submodule(db, source.file_id, &sub.name);
                 let points_to = points_to
                     .into_iter()
-                    .map(|file_id| match roots.remove(&file_id) {
-                        Some(module_id) => {
-                            self.mods[module_id].parent = Some(link);
-                            module_id
-                        }
-                        None => self.init_subtree(
+                    .map(|file_id| {
+                        self.init_subtree(
                             db,
                             source_root,
-                            visited,
-                            roots,
                             Some(link),
                             SourceItemId {
                                 file_id: file_id.into(),
                                 item_id: None,
                             },
-                        ),
+                        )
                     })
                     .collect::<Vec<_>>();
                 (points_to, problem)
             } else {
-                let points_to =
-                    self.init_subtree(db, source_root, visited, roots, Some(link), sub.source);
+                let points_to = self.init_subtree(db, source_root, Some(link), sub.source);
                 (vec![points_to], None)
             };
 
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 028c1882f..5193900e0 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -190,7 +190,12 @@ where
             self.populate_module(module_id, Arc::clone(items));
         }
 
+        let mut iter = 0;
         loop {
+            iter += 1;
+            if iter > 1000 {
+                panic!("failed to reach fixedpoint after 1000 iters")
+            }
             let processed_imports_count = self.processed_imports.len();
             for &module_id in self.input.keys() {
                 self.db.check_canceled();
diff --git a/crates/ra_hir/src/nameres/lower.rs b/crates/ra_hir/src/nameres/lower.rs
index b4fe99ea7..1d77548f3 100644
--- a/crates/ra_hir/src/nameres/lower.rs
+++ b/crates/ra_hir/src/nameres/lower.rs
@@ -129,7 +129,7 @@ impl LoweredModule {
                     let id = loc.id(db);
                     let file_id = HirFileId::from(id);
                     //FIXME: expand recursively
-                    for item in db.hir_source_file(file_id).items() {
+                    for item in db.hir_parse(file_id).items() {
                         self.add_def_id(source_map, db, module, file_id, item);
                     }
                 }
diff --git a/crates/ra_hir/src/nameres/tests.rs b/crates/ra_hir/src/nameres/tests.rs
index 24936976c..e72781f51 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::{CrateGraph, SourceRootId, FilesDatabase};
+use ra_db::{CrateGraph, SourceRootId, SourceDatabase};
 use relative_path::RelativePath;
 use test_utils::{assert_eq_text, covers};
 
diff --git a/crates/ra_hir/src/query_definitions.rs b/crates/ra_hir/src/query_definitions.rs
index cf8c7e435..61c93a964 100644
--- a/crates/ra_hir/src/query_definitions.rs
+++ b/crates/ra_hir/src/query_definitions.rs
@@ -23,7 +23,7 @@ pub(super) fn fn_scopes(db: &impl HirDatabase, func: Function) -> Arc<FnScopes>
 }
 
 pub(super) fn file_items(db: &impl HirDatabase, file_id: HirFileId) -> Arc<SourceFileItems> {
-    let source_file = db.hir_source_file(file_id);
+    let source_file = db.hir_parse(file_id);
     let res = SourceFileItems::new(file_id, &source_file);
     Arc::new(res)
 }
@@ -34,10 +34,7 @@ pub(super) fn file_item(
 ) -> TreeArc<SyntaxNode> {
     match source_item_id.item_id {
         Some(id) => db.file_items(source_item_id.file_id)[id].to_owned(),
-        None => db
-            .hir_source_file(source_item_id.file_id)
-            .syntax()
-            .to_owned(),
+        None => db.hir_parse(source_item_id.file_id).syntax().to_owned(),
     }
 }
 
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index dbe040805..c0b3f1cd4 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -43,7 +43,7 @@ pub fn module_from_declaration(
 
 /// Locates the module by position in the source code.
 pub fn module_from_position(db: &impl HirDatabase, position: FilePosition) -> Option<Module> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
     match find_node_at_offset::<ast::Module>(file.syntax(), position.offset) {
         Some(m) if !m.has_semi() => module_from_inline(db, position.file_id.into(), m),
         _ => module_from_file_id(db, position.file_id.into()),
@@ -95,7 +95,7 @@ fn module_from_source(db: &impl HirDatabase, source: SourceItemId) -> Option<Mod
 }
 
 pub fn function_from_position(db: &impl HirDatabase, position: FilePosition) -> Option<Function> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
     let fn_def = find_node_at_offset::<ast::FnDef>(file.syntax(), position.offset)?;
     function_from_source(db, position.file_id, fn_def)
 }
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index c57e222dd..179ebddee 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -38,7 +38,7 @@ use crate::{
     expr::{Body, Expr, BindingAnnotation, Literal, ExprId, Pat, PatId, UnaryOp, BinaryOp, Statement, FieldPat},
     generics::GenericParams,
     path::GenericArg,
-    adt::VariantData,
+    adt::VariantDef,
 };
 
 /// The ID of a type variable.
@@ -696,28 +696,6 @@ pub(super) fn type_for_def(db: &impl HirDatabase, def: TypableDef) -> Ty {
     }
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
-pub enum VariantDef {
-    Struct(Struct),
-    EnumVariant(EnumVariant),
-}
-impl_froms!(VariantDef: Struct, EnumVariant);
-
-impl VariantDef {
-    pub(crate) fn field(self, db: &impl HirDatabase, name: &Name) -> Option<StructField> {
-        match self {
-            VariantDef::Struct(it) => it.field(db, name),
-            VariantDef::EnumVariant(it) => it.field(db, name),
-        }
-    }
-    pub(crate) fn variant_data(self, db: &impl HirDatabase) -> Arc<VariantData> {
-        match self {
-            VariantDef::Struct(it) => it.variant_data(db),
-            VariantDef::EnumVariant(it) => it.variant_data(db),
-        }
-    }
-}
-
 pub(super) fn type_for_field(db: &impl HirDatabase, field: StructField) -> Ty {
     let parent_def = field.parent_def(db);
     let (generics, module) = match parent_def {
@@ -732,8 +710,10 @@ pub(super) fn type_for_field(db: &impl HirDatabase, field: StructField) -> Ty {
 /// The result of type inference: A mapping from expressions and patterns to types.
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct InferenceResult {
-    /// For each method call expr, record the function it resolved to.
+    /// For each method call expr, records the function it resolves to.
     method_resolutions: FxHashMap<ExprId, Function>,
+    /// For each field access expr, records the field it resolves to.
+    field_resolutions: FxHashMap<ExprId, StructField>,
     type_of_expr: ArenaMap<ExprId, Ty>,
     type_of_pat: ArenaMap<PatId, Ty>,
 }
@@ -742,6 +722,9 @@ impl InferenceResult {
     pub fn method_resolution(&self, expr: ExprId) -> Option<Function> {
         self.method_resolutions.get(&expr).map(|it| *it)
     }
+    pub fn field_resolution(&self, expr: ExprId) -> Option<StructField> {
+        self.field_resolutions.get(&expr).map(|it| *it)
+    }
 }
 
 impl Index<ExprId> for InferenceResult {
@@ -770,6 +753,7 @@ struct InferenceContext<'a, D: HirDatabase> {
     impl_block: Option<ImplBlock>,
     var_unification_table: InPlaceUnificationTable<TypeVarId>,
     method_resolutions: FxHashMap<ExprId, Function>,
+    field_resolutions: FxHashMap<ExprId, StructField>,
     type_of_expr: ArenaMap<ExprId, Ty>,
     type_of_pat: ArenaMap<PatId, Ty>,
     /// The return type of the function being inferred.
@@ -806,7 +790,10 @@ fn binary_op_return_ty(op: BinaryOp, rhs_ty: Ty) -> Ty {
         | BinaryOp::BitwiseAnd
         | BinaryOp::BitwiseOr
         | BinaryOp::BitwiseXor => match rhs_ty {
-            Ty::Int(..) | Ty::Float(..) => rhs_ty,
+            Ty::Int(..)
+            | Ty::Float(..)
+            | Ty::Infer(InferTy::IntVar(..))
+            | Ty::Infer(InferTy::FloatVar(..)) => rhs_ty,
             _ => Ty::Unknown,
         },
         BinaryOp::RangeRightOpen | BinaryOp::RangeRightClosed => Ty::Unknown,
@@ -861,6 +848,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     ) -> Self {
         InferenceContext {
             method_resolutions: FxHashMap::default(),
+            field_resolutions: FxHashMap::default(),
             type_of_expr: ArenaMap::default(),
             type_of_pat: ArenaMap::default(),
             var_unification_table: InPlaceUnificationTable::new(),
@@ -886,6 +874,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         }
         InferenceResult {
             method_resolutions: mem::replace(&mut self.method_resolutions, Default::default()),
+            field_resolutions: mem::replace(&mut self.field_resolutions, Default::default()),
             type_of_expr: expr_types,
             type_of_pat: pat_types,
         }
@@ -899,6 +888,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         self.method_resolutions.insert(expr, func);
     }
 
+    fn write_field_resolution(&mut self, expr: ExprId, field: StructField) {
+        self.field_resolutions.insert(expr, field);
+    }
+
     fn write_pat_ty(&mut self, pat: PatId, ty: Ty) {
         self.type_of_pat.insert(pat, ty);
     }
@@ -1251,9 +1244,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         ty
     }
 
-    fn infer_expr(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
+    fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
         let body = Arc::clone(&self.body); // avoid borrow checker problem
-        let ty = match &body[expr] {
+        let ty = match &body[tgt_expr] {
             Expr::Missing => Ty::Unknown,
             Expr::If {
                 condition,
@@ -1344,7 +1337,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let resolved = receiver_ty.clone().lookup_method(self.db, method_name);
                 let method_ty = match resolved {
                     Some(func) => {
-                        self.write_method_resolution(expr, func);
+                        self.write_method_resolution(tgt_expr, func);
                         self.db.type_for_def(func.into())
                     }
                     None => Ty::Unknown,
@@ -1389,7 +1382,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 expected.ty
             }
-            Expr::Path(p) => self.infer_path_expr(expr, p).unwrap_or(Ty::Unknown),
+            Expr::Path(p) => self.infer_path_expr(tgt_expr, p).unwrap_or(Ty::Unknown),
             Expr::Continue => Ty::Never,
             Expr::Break { expr } => {
                 if let Some(expr) = expr {
@@ -1436,9 +1429,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                             def_id: AdtDef::Struct(s),
                             ref substs,
                             ..
-                        } => s
-                            .field(self.db, name)
-                            .map(|field| field.ty(self.db).subst(substs)),
+                        } => s.field(self.db, name).map(|field| {
+                            self.write_field_resolution(tgt_expr, field);
+                            field.ty(self.db).subst(substs)
+                        }),
                         _ => None,
                     })
                     .unwrap_or(Ty::Unknown);
@@ -1545,7 +1539,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         let ty = self.insert_type_vars_shallow(ty);
         self.unify(&ty, &expected.ty);
         let ty = self.resolve_ty_as_possible(ty);
-        self.write_expr_ty(expr, ty.clone());
+        self.write_expr_ty(tgt_expr, ty.clone());
         ty
     }
 
diff --git a/crates/ra_hir/src/ty/snapshots/tests__bug_651.snap b/crates/ra_hir/src/ty/snapshots/tests__bug_651.snap
new file mode 100644
index 000000000..d23d3f139
--- /dev/null
+++ b/crates/ra_hir/src/ty/snapshots/tests__bug_651.snap
@@ -0,0 +1,13 @@
+---
+created: "2019-01-25T20:31:47.275112244+00:00"
+creator: [email protected]
+expression: "&result"
+source: crates/ra_hir/src/ty/tests.rs
+---
+[11; 41) '{     ...+ y; }': ()
+[21; 22) 'y': i32
+[25; 27) '92': i32
+[33; 34) '1': i32
+[33; 38) '1 + y': i32
+[37; 38) 'y': i32
+
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 92c74cf00..e0b0689f8 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -1,7 +1,7 @@
 use std::sync::Arc;
 use std::fmt::Write;
 
-use ra_db::{SyntaxDatabase, salsa::Database};
+use ra_db::{SourceDatabase, salsa::Database};
 use ra_syntax::ast::{self, AstNode};
 
 use crate::{
@@ -532,9 +532,22 @@ fn test() {
     );
 }
 
+#[test]
+fn bug_651() {
+    check_inference(
+        "bug_651",
+        r#"
+fn quux() {
+    let y = 92;
+    1 + y;
+}
+"#,
+    );
+}
+
 fn infer(content: &str) -> String {
     let (db, _, file_id) = MockDatabase::with_single_file(content);
-    let source_file = db.source_file(file_id);
+    let source_file = db.parse(file_id);
     let mut acc = String::new();
     for fn_def in source_file
         .syntax()
diff --git a/crates/ra_ide_api/Cargo.toml b/crates/ra_ide_api/Cargo.toml
index 61942bbbb..79e473463 100644
--- a/crates/ra_ide_api/Cargo.toml
+++ b/crates/ra_ide_api/Cargo.toml
@@ -6,6 +6,7 @@ authors = ["Aleksey Kladov <[email protected]>"]
 
 [dependencies]
 itertools = "0.8.0"
+join_to_string = "0.1.3"
 log = "0.4.5"
 relative-path = "0.4.0"
 rayon = "1.0.2"
@@ -13,7 +14,6 @@ fst = "0.3.1"
 rustc-hash = "1.0"
 parking_lot = "0.7.0"
 unicase = "2.2.0"
-salsa = "0.10.0-alpha3"
 
 ra_syntax = { path = "../ra_syntax" }
 ra_ide_api_light = { path = "../ra_ide_api_light" }
diff --git a/crates/ra_ide_api/src/call_info.rs b/crates/ra_ide_api/src/call_info.rs
index 0449c1902..3267fff96 100644
--- a/crates/ra_ide_api/src/call_info.rs
+++ b/crates/ra_ide_api/src/call_info.rs
@@ -1,4 +1,4 @@
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 use ra_syntax::{
     AstNode, SyntaxNode, TextUnit, TextRange,
     SyntaxKind::FN_DEF,
@@ -10,7 +10,7 @@ use crate::{FilePosition, CallInfo, db::RootDatabase};
 
 /// Computes parameter information for the given call expression.
 pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<CallInfo> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
     let syntax = file.syntax();
 
     // Find the calling expression and it's NameRef
@@ -22,7 +22,7 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<Cal
     let symbol = file_symbols
         .into_iter()
         .find(|it| it.ptr.kind() == FN_DEF)?;
-    let fn_file = db.source_file(symbol.file_id);
+    let fn_file = db.parse(symbol.file_id);
     let fn_def = symbol.ptr.to_node(&fn_file);
     let fn_def = ast::FnDef::cast(fn_def).unwrap();
     let mut call_info = CallInfo::new(fn_def)?;
diff --git a/crates/ra_ide_api/src/completion.rs b/crates/ra_ide_api/src/completion.rs
index 565d57c37..b1867de42 100644
--- a/crates/ra_ide_api/src/completion.rs
+++ b/crates/ra_ide_api/src/completion.rs
@@ -9,7 +9,7 @@ mod complete_path;
 mod complete_scope;
 mod complete_postfix;
 
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 
 use crate::{
     db,
@@ -45,7 +45,7 @@ pub use crate::completion::completion_item::{CompletionItem, CompletionItemKind,
 /// identifier prefix/fuzzy match should be done higher in the stack, together
 /// with ordering of completions (currently this is done by the client).
 pub(crate) fn completions(db: &db::RootDatabase, position: FilePosition) -> Option<Completions> {
-    let original_file = db.source_file(position.file_id);
+    let original_file = db.parse(position.file_id);
     let ctx = CompletionContext::new(db, &original_file, position)?;
 
     let mut acc = Completions::default();
diff --git a/crates/ra_ide_api/src/completion/complete_dot.rs b/crates/ra_ide_api/src/completion/complete_dot.rs
index 060a46c5e..bad51cc51 100644
--- a/crates/ra_ide_api/src/completion/complete_dot.rs
+++ b/crates/ra_ide_api/src/completion/complete_dot.rs
@@ -1,4 +1,4 @@
-use hir::{Ty, AdtDef};
+use hir::{Ty, AdtDef, Docs};
 
 use crate::completion::{CompletionContext, Completions, CompletionItem, CompletionItemKind};
 use crate::completion::completion_item::CompletionKind;
@@ -38,6 +38,7 @@ fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: Ty)
                             )
                             .kind(CompletionItemKind::Field)
                             .detail(field.ty(ctx.db).subst(substs).to_string())
+                            .set_documentation(field.docs(ctx.db))
                             .add_to(acc);
                         }
                     }
@@ -107,7 +108,10 @@ mod tests {
         check_ref_completion(
             "struct_field_completion_self",
             r"
-            struct A { the_field: (u32,) }
+            struct A {
+                /// This is the_field
+                the_field: (u32,)
+            }
             impl A {
                 fn foo(self) {
                     self.<|>
diff --git a/crates/ra_ide_api/src/completion/complete_path.rs b/crates/ra_ide_api/src/completion/complete_path.rs
index e3f1d42f8..b33ddcde5 100644
--- a/crates/ra_ide_api/src/completion/complete_path.rs
+++ b/crates/ra_ide_api/src/completion/complete_path.rs
@@ -1,3 +1,5 @@
+use join_to_string::join;
+
 use crate::{
     completion::{CompletionItem, CompletionItemKind, Completions, CompletionKind, CompletionContext},
 };
@@ -29,6 +31,15 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
         hir::ModuleDef::Enum(e) => {
             e.variants(ctx.db).into_iter().for_each(|variant| {
                 if let Some(name) = variant.name(ctx.db) {
+                    let detail_types = variant
+                        .fields(ctx.db)
+                        .into_iter()
+                        .map(|field| field.ty(ctx.db));
+                    let detail = join(detail_types)
+                        .separator(", ")
+                        .surround_with("(", ")")
+                        .to_string();
+
                     CompletionItem::new(
                         CompletionKind::Reference,
                         ctx.source_range(),
@@ -36,6 +47,7 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
                     )
                     .kind(CompletionItemKind::EnumVariant)
                     .set_documentation(variant.docs(ctx.db))
+                    .set_detail(Some(detail))
                     .add_to(acc)
                 }
             });
@@ -54,6 +66,22 @@ mod tests {
     }
 
     #[test]
+    fn completes_mod_with_docs() {
+        check_reference_completion(
+            "mod_with_docs",
+            r"
+            use self::my<|>;
+
+            /// Some simple
+            /// docs describing `mod my`.
+            mod my {
+                struct Bar;
+            }
+            ",
+        );
+    }
+
+    #[test]
     fn completes_use_item_starting_with_self() {
         check_reference_completion(
             "use_item_starting_with_self",
@@ -116,7 +144,7 @@ mod tests {
     #[test]
     fn completes_enum_variant() {
         check_reference_completion(
-            "reference_completion",
+            "enum_variant",
             "
             //- /lib.rs
             /// An enum
@@ -130,4 +158,25 @@ mod tests {
             ",
         );
     }
+
+    #[test]
+    fn completes_enum_variant_with_details() {
+        check_reference_completion(
+            "enum_variant_with_details",
+            "
+            //- /lib.rs
+            struct S { field: u32 }
+            /// An enum
+            enum E {
+                /// Foo Variant (empty)
+                Foo,
+                /// Bar Variant with i32 and u32
+                Bar(i32, u32),
+                ///
+                S(S),
+            }
+            fn foo() { let _ = E::<|> }
+            ",
+        );
+    }
 }
diff --git a/crates/ra_ide_api/src/completion/completion_item.rs b/crates/ra_ide_api/src/completion/completion_item.rs
index b2b047766..b16ac2b28 100644
--- a/crates/ra_ide_api/src/completion/completion_item.rs
+++ b/crates/ra_ide_api/src/completion/completion_item.rs
@@ -215,7 +215,7 @@ impl Builder {
             Some(it) => it,
         };
         let (kind, docs) = match def {
-            hir::ModuleDef::Module(_) => (CompletionItemKind::Module, None),
+            hir::ModuleDef::Module(it) => (CompletionItemKind::Module, it.docs(ctx.db)),
             hir::ModuleDef::Function(func) => return self.from_function(ctx, func),
             hir::ModuleDef::Struct(it) => (CompletionItemKind::Struct, it.docs(ctx.db)),
             hir::ModuleDef::Enum(it) => (CompletionItemKind::Enum, it.docs(ctx.db)),
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__reference_completion.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant.snap
index e46f7807b..8c84439b2 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__reference_completion.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant.snap
@@ -1,8 +1,8 @@
 ---
-created: "2019-01-23T23:49:43.278245900+00:00"
-creator: [email protected].1
+created: "2019-01-25T16:44:04.640545300+00:00"
+creator: [email protected].2
 expression: kind_completions
-source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
+source: crates/ra_ide_api/src/completion/completion_item.rs
 ---
 [
     CompletionItem {
@@ -11,7 +11,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             EnumVariant
         ),
-        detail: None,
+        detail: Some(
+            "()"
+        ),
         documentation: Some(
             Documentation(
                 "Foo Variant"
@@ -29,7 +31,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             EnumVariant
         ),
-        detail: None,
+        detail: Some(
+            "(i32)"
+        ),
         documentation: Some(
             Documentation(
                 "Bar Variant with i32"
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant_with_details.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant_with_details.snap
new file mode 100644
index 000000000..384634517
--- /dev/null
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant_with_details.snap
@@ -0,0 +1,64 @@
+---
+created: "2019-01-25T16:44:04.641542400+00:00"
+creator: [email protected]
+expression: kind_completions
+source: crates/ra_ide_api/src/completion/completion_item.rs
+---
+[
+    CompletionItem {
+        completion_kind: Reference,
+        label: "Foo",
+        kind: Some(
+            EnumVariant
+        ),
+        detail: Some(
+            "()"
+        ),
+        documentation: Some(
+            Documentation(
+                "Foo Variant (empty)"
+            )
+        ),
+        lookup: None,
+        insert_text: None,
+        insert_text_format: PlainText,
+        source_range: [180; 180),
+        text_edit: None
+    },
+    CompletionItem {
+        completion_kind: Reference,
+        label: "Bar",
+        kind: Some(
+            EnumVariant
+        ),
+        detail: Some(
+            "(i32, u32)"
+        ),
+        documentation: Some(
+            Documentation(
+                "Bar Variant with i32 and u32"
+            )
+        ),
+        lookup: None,
+        insert_text: None,
+        insert_text_format: PlainText,
+        source_range: [180; 180),
+        text_edit: None
+    },
+    CompletionItem {
+        completion_kind: Reference,
+        label: "S",
+        kind: Some(
+            EnumVariant
+        ),
+        detail: Some(
+            "(S)"
+        ),
+        documentation: None,
+        lookup: None,
+        insert_text: None,
+        insert_text_format: PlainText,
+        source_range: [180; 180),
+        text_edit: None
+    }
+]
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__mod_with_docs.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__mod_with_docs.snap
new file mode 100644
index 000000000..3db7119a7
--- /dev/null
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__mod_with_docs.snap
@@ -0,0 +1,26 @@
+---
+created: "2019-01-25T17:49:28.949186500+00:00"
+creator: [email protected]
+expression: kind_completions
+source: crates/ra_ide_api/src/completion/completion_item.rs
+---
+[
+    CompletionItem {
+        completion_kind: Reference,
+        label: "my",
+        kind: Some(
+            Module
+        ),
+        detail: None,
+        documentation: Some(
+            Documentation(
+                "Some simple\ndocs describing `mod my`."
+            )
+        ),
+        lookup: None,
+        insert_text: None,
+        insert_text_format: PlainText,
+        source_range: [23; 25),
+        text_edit: None
+    }
+]
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_self.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_self.snap
index 80e8f3df5..580e92a90 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_self.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_self.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-23T13:19:23.501297515+00:00"
+created: "2019-01-25T19:27:09.519688600+00:00"
 creator: [email protected]
 expression: kind_completions
 source: crates/ra_ide_api/src/completion/completion_item.rs
@@ -14,11 +14,15 @@ source: crates/ra_ide_api/src/completion/completion_item.rs
         detail: Some(
             "(u32,)"
         ),
-        documentation: None,
+        documentation: Some(
+            Documentation(
+                "This is the_field"
+            )
+        ),
         lookup: None,
         insert_text: None,
         insert_text_format: PlainText,
-        source_range: [121; 121),
+        source_range: [187; 187),
         text_edit: None
     },
     CompletionItem {
@@ -36,7 +40,7 @@ source: crates/ra_ide_api/src/completion/completion_item.rs
             "foo()$0"
         ),
         insert_text_format: Snippet,
-        source_range: [121; 121),
+        source_range: [187; 187),
         text_edit: None
     }
 ]
diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index f0190ae51..3da93ec35 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -1,18 +1,17 @@
 use std::sync::Arc;
 
 use ra_db::{
-    BaseDatabase, FileId, Canceled,
-    salsa::{self, Database},
+    CheckCanceled, FileId, Canceled, SourceDatabase,
+    salsa,
 };
 
-use crate::{symbol_index, LineIndex};
+use crate::{LineIndex, symbol_index::{self, SymbolsDatabase}};
 
 #[salsa::database(
-    ra_db::FilesDatabase,
-    ra_db::SyntaxDatabase,
-    LineIndexDatabase,
-    symbol_index::SymbolsDatabase,
-    hir::db::HirDatabase
+    ra_db::SourceDatabaseStorage,
+    LineIndexDatabaseStorage,
+    symbol_index::SymbolsDatabaseStorage,
+    hir::db::HirDatabaseStorage
 )]
 #[derive(Debug)]
 pub(crate) struct RootDatabase {
@@ -35,12 +34,9 @@ impl Default for RootDatabase {
             runtime: salsa::Runtime::default(),
             interner: Default::default(),
         };
-        db.query_mut(ra_db::CrateGraphQuery)
-            .set((), Default::default());
-        db.query_mut(ra_db::LocalRootsQuery)
-            .set((), Default::default());
-        db.query_mut(ra_db::LibraryRootsQuery)
-            .set((), Default::default());
+        db.set_crate_graph(Default::default());
+        db.set_local_roots(Default::default());
+        db.set_library_roots(Default::default());
         db
     }
 }
@@ -54,7 +50,7 @@ impl salsa::ParallelDatabase for RootDatabase {
     }
 }
 
-impl BaseDatabase for RootDatabase {}
+impl CheckCanceled for RootDatabase {}
 
 impl AsRef<hir::HirInterner> for RootDatabase {
     fn as_ref(&self) -> &hir::HirInterner {
@@ -62,12 +58,12 @@ impl AsRef<hir::HirInterner> for RootDatabase {
     }
 }
 
-#[salsa::query_group]
-pub(crate) trait LineIndexDatabase: ra_db::FilesDatabase + BaseDatabase {
+#[salsa::query_group(LineIndexDatabaseStorage)]
+pub(crate) trait LineIndexDatabase: ra_db::SourceDatabase + CheckCanceled {
     fn line_index(&self, file_id: FileId) -> Arc<LineIndex>;
 }
 
-fn line_index(db: &impl ra_db::FilesDatabase, file_id: FileId) -> Arc<LineIndex> {
+fn line_index(db: &impl ra_db::SourceDatabase, file_id: FileId) -> Arc<LineIndex> {
     let text = db.file_text(file_id);
     Arc::new(LineIndex::new(&*text))
 }
diff --git a/crates/ra_ide_api/src/extend_selection.rs b/crates/ra_ide_api/src/extend_selection.rs
index 718b4def5..cd2ebe471 100644
--- a/crates/ra_ide_api/src/extend_selection.rs
+++ b/crates/ra_ide_api/src/extend_selection.rs
@@ -1,4 +1,4 @@
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 use ra_syntax::{
     SyntaxNode, AstNode, SourceFile,
     ast, algo::find_covering_node,
@@ -10,7 +10,7 @@ use crate::{
 };
 
 pub(crate) fn extend_selection(db: &RootDatabase, frange: FileRange) -> TextRange {
-    let source_file = db.source_file(frange.file_id);
+    let source_file = db.parse(frange.file_id);
     if let Some(range) = extend_selection_in_macro(db, &source_file, frange) {
         return range;
     }
diff --git a/crates/ra_ide_api/src/goto_definition.rs b/crates/ra_ide_api/src/goto_definition.rs
index 46bdde00d..2a20c20ee 100644
--- a/crates/ra_ide_api/src/goto_definition.rs
+++ b/crates/ra_ide_api/src/goto_definition.rs
@@ -1,8 +1,9 @@
-use ra_db::{FileId, SyntaxDatabase};
+use ra_db::{FileId, SourceDatabase};
 use ra_syntax::{
     AstNode, ast,
     algo::find_node_at_offset,
 };
+use test_utils::tested_by;
 
 use crate::{FilePosition, NavigationTarget, db::RootDatabase, RangeInfo};
 
@@ -10,7 +11,7 @@ pub(crate) fn goto_definition(
     db: &RootDatabase,
     position: FilePosition,
 ) -> Option<RangeInfo<Vec<NavigationTarget>>> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
     let syntax = file.syntax();
     if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(syntax, position.offset) {
         let navs = reference_definition(db, position.file_id, name_ref).to_vec();
@@ -60,6 +61,7 @@ pub(crate) fn reference_definition(
             .parent()
             .and_then(ast::MethodCallExpr::cast)
         {
+            tested_by!(goto_definition_works_for_methods);
             let infer_result = function.infer(db);
             let syntax_mapping = function.body_syntax_mapping(db);
             let expr = ast::Expr::cast(method_call.syntax()).unwrap();
@@ -70,6 +72,19 @@ pub(crate) fn reference_definition(
                 return Exact(NavigationTarget::from_function(db, func));
             };
         }
+        // It could also be a field access
+        if let Some(field_expr) = name_ref.syntax().parent().and_then(ast::FieldExpr::cast) {
+            tested_by!(goto_definition_works_for_fields);
+            let infer_result = function.infer(db);
+            let syntax_mapping = function.body_syntax_mapping(db);
+            let expr = ast::Expr::cast(field_expr.syntax()).unwrap();
+            if let Some(field) = syntax_mapping
+                .node_expr(expr)
+                .and_then(|it| infer_result.field_resolution(it))
+            {
+                return Exact(NavigationTarget::from_field(db, field));
+            };
+        }
     }
     // Then try module name resolution
     if let Some(module) = hir::source_binder::module_from_child_node(db, file_id, name_ref.syntax())
@@ -82,9 +97,7 @@ 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) {
-                    return Exact(target);
-                }
+                return Exact(NavigationTarget::from_def(db, def_id));
             }
         }
     }
@@ -117,6 +130,8 @@ fn name_definition(
 
 #[cfg(test)]
 mod tests {
+    use test_utils::covers;
+
     use crate::mock_analysis::analysis_and_position;
 
     fn check_goto(fixuture: &str, expected: &str) {
@@ -183,6 +198,7 @@ mod tests {
 
     #[test]
     fn goto_definition_works_for_methods() {
+        covers!(goto_definition_works_for_methods);
         check_goto(
             "
             //- /lib.rs
@@ -197,15 +213,23 @@ mod tests {
             ",
             "frobnicate FN_DEF FileId(1) [27; 52) [30; 40)",
         );
+    }
 
+    #[test]
+    fn goto_definition_works_for_fields() {
+        covers!(goto_definition_works_for_fields);
         check_goto(
             "
             //- /lib.rs
-            mod <|>foo;
-            //- /foo/mod.rs
-            // empty
+            struct Foo {
+                spam: u32,
+            }
+
+            fn bar(foo: &Foo) {
+                foo.spam<|>;
+            }
             ",
-            "foo SOURCE_FILE FileId(2) [0; 10)",
+            "spam NAMED_FIELD_DEF FileId(1) [17; 26) [17; 21)",
         );
     }
 }
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 4d4bfbc4d..ff9ae2d9c 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -1,4 +1,4 @@
-use ra_db::{SyntaxDatabase};
+use ra_db::SourceDatabase;
 use ra_syntax::{
     AstNode, SyntaxNode, TreeArc, ast,
     algo::{find_covering_node, find_node_at_offset, find_leaf_at_offset, visit::{visitor, Visitor}},
@@ -7,7 +7,7 @@ use ra_syntax::{
 use crate::{db::RootDatabase, RangeInfo, FilePosition, FileRange, NavigationTarget};
 
 pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeInfo<String>> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
     let mut res = Vec::new();
 
     let mut range = None;
@@ -53,7 +53,7 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
 }
 
 pub(crate) fn type_of(db: &RootDatabase, frange: FileRange) -> Option<String> {
-    let file = db.source_file(frange.file_id);
+    let file = db.parse(frange.file_id);
     let syntax = file.syntax();
     let leaf_node = find_covering_node(syntax, frange.range);
     // if we picked identifier, expand to pattern/expression
@@ -88,7 +88,7 @@ fn doc_text_for(db: &RootDatabase, nav: NavigationTarget) -> Option<String> {
 
 impl NavigationTarget {
     fn node(&self, db: &RootDatabase) -> Option<TreeArc<SyntaxNode>> {
-        let source_file = db.source_file(self.file_id());
+        let source_file = db.parse(self.file_id());
         let source_file = source_file.syntax();
         let node = source_file
             .descendants()
diff --git a/crates/ra_ide_api/src/imp.rs b/crates/ra_ide_api/src/imp.rs
index 961f7b230..399433a01 100644
--- a/crates/ra_ide_api/src/imp.rs
+++ b/crates/ra_ide_api/src/imp.rs
@@ -4,8 +4,8 @@ use hir::{
     self, Problem, source_binder
 };
 use ra_db::{
-    FilesDatabase, SourceRoot, SourceRootId, SyntaxDatabase,
-    salsa::Database,
+    SourceDatabase, SourceRoot, SourceRootId,
+    salsa::{Database, SweepStrategy},
 };
 use ra_ide_api_light::{self, assists, LocalEdit, Severity};
 use ra_syntax::{
@@ -76,14 +76,14 @@ impl db::RootDatabase {
     /// syntax trees. However, if we actually do that, everything is recomputed
     /// for some reason. Needs investigation.
     pub(crate) fn collect_garbage(&mut self) {
-        self.query(ra_db::SourceFileQuery)
-            .sweep(salsa::SweepStrategy::default().discard_values());
-        self.query(hir::db::HirSourceFileQuery)
-            .sweep(salsa::SweepStrategy::default().discard_values());
+        self.query(ra_db::ParseQuery)
+            .sweep(SweepStrategy::default().discard_values());
+        self.query(hir::db::HirParseQuery)
+            .sweep(SweepStrategy::default().discard_values());
         self.query(hir::db::FileItemsQuery)
-            .sweep(salsa::SweepStrategy::default().discard_values());
+            .sweep(SweepStrategy::default().discard_values());
         self.query(hir::db::FileItemQuery)
-            .sweep(salsa::SweepStrategy::default().discard_values());
+            .sweep(SweepStrategy::default().discard_values());
     }
 }
 
@@ -102,7 +102,7 @@ impl db::RootDatabase {
     }
 
     pub(crate) fn find_all_refs(&self, position: FilePosition) -> Vec<(FileId, TextRange)> {
-        let file = self.source_file(position.file_id);
+        let file = self.parse(position.file_id);
         // Find the binding associated with the offset
         let (binding, descr) = match find_binding(self, &file, position) {
             None => return Vec::new(),
@@ -150,7 +150,7 @@ impl db::RootDatabase {
     }
 
     pub(crate) fn diagnostics(&self, file_id: FileId) -> Vec<Diagnostic> {
-        let syntax = self.source_file(file_id);
+        let syntax = self.parse(file_id);
 
         let mut res = ra_ide_api_light::diagnostics(&syntax)
             .into_iter()
@@ -214,7 +214,7 @@ impl db::RootDatabase {
     }
 
     pub(crate) fn assists(&self, frange: FileRange) -> Vec<SourceChange> {
-        let file = self.source_file(frange.file_id);
+        let file = self.parse(frange.file_id);
         assists::assists(&file, frange.range)
             .into_iter()
             .map(|local_edit| SourceChange::from_local_edit(frange.file_id, local_edit))
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index ffd026b04..43c8bea71 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -34,7 +34,7 @@ use std::{fmt, sync::Arc};
 use ra_syntax::{SourceFile, TreeArc, TextRange, TextUnit};
 use ra_text_edit::TextEdit;
 use ra_db::{
-    SyntaxDatabase, FilesDatabase, BaseDatabase,
+    SourceDatabase, CheckCanceled,
     salsa::{self, ParallelDatabase},
 };
 use rayon::prelude::*;
@@ -313,7 +313,7 @@ impl Analysis {
 
     /// Gets the syntax tree of the file.
     pub fn parse(&self, file_id: FileId) -> TreeArc<SourceFile> {
-        self.db.source_file(file_id).clone()
+        self.db.parse(file_id).clone()
     }
 
     /// Gets the file's `LineIndex`: data structure to convert between absolute
@@ -330,21 +330,21 @@ impl Analysis {
     /// Returns position of the mathcing brace (all types of braces are
     /// supported).
     pub fn matching_brace(&self, position: FilePosition) -> Option<TextUnit> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.db.parse(position.file_id);
         ra_ide_api_light::matching_brace(&file, position.offset)
     }
 
     /// Returns a syntax tree represented as `String`, for debug purposes.
     // FIXME: use a better name here.
     pub fn syntax_tree(&self, file_id: FileId) -> String {
-        let file = self.db.source_file(file_id);
+        let file = self.db.parse(file_id);
         ra_ide_api_light::syntax_tree(&file)
     }
 
     /// Returns an edit to remove all newlines in the range, cleaning up minor
     /// stuff like trailing commas.
     pub fn join_lines(&self, frange: FileRange) -> SourceChange {
-        let file = self.db.source_file(frange.file_id);
+        let file = self.db.parse(frange.file_id);
         SourceChange::from_local_edit(
             frange.file_id,
             ra_ide_api_light::join_lines(&file, frange.range),
@@ -354,7 +354,7 @@ impl Analysis {
     /// Returns an edit which should be applied when opening a new line, fixing
     /// up minor stuff like continuing the comment.
     pub fn on_enter(&self, position: FilePosition) -> Option<SourceChange> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.db.parse(position.file_id);
         let edit = ra_ide_api_light::on_enter(&file, position.offset)?;
         Some(SourceChange::from_local_edit(position.file_id, edit))
     }
@@ -363,14 +363,14 @@ impl Analysis {
     /// this works when adding `let =`.
     // FIXME: use a snippet completion instead of this hack here.
     pub fn on_eq_typed(&self, position: FilePosition) -> Option<SourceChange> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.db.parse(position.file_id);
         let edit = ra_ide_api_light::on_eq_typed(&file, position.offset)?;
         Some(SourceChange::from_local_edit(position.file_id, edit))
     }
 
     /// Returns an edit which should be applied when a dot ('.') is typed on a blank line, indenting the line appropriately.
     pub fn on_dot_typed(&self, position: FilePosition) -> Option<SourceChange> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.db.parse(position.file_id);
         let edit = ra_ide_api_light::on_dot_typed(&file, position.offset)?;
         Some(SourceChange::from_local_edit(position.file_id, edit))
     }
@@ -378,13 +378,13 @@ impl Analysis {
     /// Returns a tree representation of symbols in the file. Useful to draw a
     /// file outline.
     pub fn file_structure(&self, file_id: FileId) -> Vec<StructureNode> {
-        let file = self.db.source_file(file_id);
+        let file = self.db.parse(file_id);
         ra_ide_api_light::file_structure(&file)
     }
 
     /// Returns the set of folding ranges.
     pub fn folding_ranges(&self, file_id: FileId) -> Vec<Fold> {
-        let file = self.db.source_file(file_id);
+        let file = self.db.parse(file_id);
         ra_ide_api_light::folding_ranges(&file)
     }
 
diff --git a/crates/ra_ide_api/src/marks.rs b/crates/ra_ide_api/src/marks.rs
index dc5b2702a..e33bf6c91 100644
--- a/crates/ra_ide_api/src/marks.rs
+++ b/crates/ra_ide_api/src/marks.rs
@@ -1 +1,5 @@
-test_utils::marks!(inserts_parens_for_function_calls);
+test_utils::marks!(
+    inserts_parens_for_function_calls
+    goto_definition_works_for_methods
+    goto_definition_works_for_fields
+);
diff --git a/crates/ra_ide_api/src/navigation_target.rs b/crates/ra_ide_api/src/navigation_target.rs
index c5be8e01b..d73d4afa7 100644
--- a/crates/ra_ide_api/src/navigation_target.rs
+++ b/crates/ra_ide_api/src/navigation_target.rs
@@ -3,7 +3,7 @@ use ra_syntax::{
     SyntaxNode, AstNode, SmolStr, TextRange, ast,
     SyntaxKind::{self, NAME},
 };
-use hir::{ModuleSource};
+use hir::{ModuleSource, FieldSource};
 
 use crate::{FileSymbol, db::RootDatabase};
 
@@ -101,62 +101,48 @@ impl NavigationTarget {
         NavigationTarget::from_named(file_id.original_file(db), &*fn_def)
     }
 
-    // TODO once Def::Item is gone, this should be able to always return a NavigationTarget
-    pub(crate) fn from_def(
-        db: &RootDatabase,
-        module_def: hir::ModuleDef,
-    ) -> Option<NavigationTarget> {
+    pub(crate) fn from_field(db: &RootDatabase, field: hir::StructField) -> NavigationTarget {
+        let (file_id, field) = field.source(db);
+        let file_id = file_id.original_file(db);
+        match field {
+            FieldSource::Named(it) => NavigationTarget::from_named(file_id, &*it),
+            FieldSource::Pos(it) => {
+                NavigationTarget::from_syntax(file_id, "".into(), None, it.syntax())
+            }
+        }
+    }
+
+    pub(crate) fn from_def(db: &RootDatabase, module_def: hir::ModuleDef) -> NavigationTarget {
         match module_def {
-            hir::ModuleDef::Module(module) => Some(NavigationTarget::from_module(db, module)),
-            hir::ModuleDef::Function(func) => Some(NavigationTarget::from_function(db, func)),
+            hir::ModuleDef::Module(module) => NavigationTarget::from_module(db, module),
+            hir::ModuleDef::Function(func) => NavigationTarget::from_function(db, func),
             hir::ModuleDef::Struct(s) => {
                 let (file_id, node) = s.source(db);
-                Some(NavigationTarget::from_named(
-                    file_id.original_file(db),
-                    &*node,
-                ))
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
             }
             hir::ModuleDef::Const(s) => {
                 let (file_id, node) = s.source(db);
-                Some(NavigationTarget::from_named(
-                    file_id.original_file(db),
-                    &*node,
-                ))
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
             }
             hir::ModuleDef::Static(s) => {
                 let (file_id, node) = s.source(db);
-                Some(NavigationTarget::from_named(
-                    file_id.original_file(db),
-                    &*node,
-                ))
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
             }
             hir::ModuleDef::Enum(e) => {
                 let (file_id, node) = e.source(db);
-                Some(NavigationTarget::from_named(
-                    file_id.original_file(db),
-                    &*node,
-                ))
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
             }
             hir::ModuleDef::EnumVariant(var) => {
                 let (file_id, node) = var.source(db);
-                Some(NavigationTarget::from_named(
-                    file_id.original_file(db),
-                    &*node,
-                ))
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
             }
             hir::ModuleDef::Trait(e) => {
                 let (file_id, node) = e.source(db);
-                Some(NavigationTarget::from_named(
-                    file_id.original_file(db),
-                    &*node,
-                ))
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
             }
             hir::ModuleDef::Type(e) => {
                 let (file_id, node) = e.source(db);
-                Some(NavigationTarget::from_named(
-                    file_id.original_file(db),
-                    &*node,
-                ))
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
             }
         }
     }
diff --git a/crates/ra_ide_api/src/rename.rs b/crates/ra_ide_api/src/rename.rs
index 5b767addd..db5ccf969 100644
--- a/crates/ra_ide_api/src/rename.rs
+++ b/crates/ra_ide_api/src/rename.rs
@@ -17,7 +17,7 @@ use crate::{
     SourceChange,
     SourceFileEdit,
 };
-use ra_db::{FilesDatabase, SyntaxDatabase};
+use ra_db::SourceDatabase;
 use relative_path::RelativePath;
 
 pub(crate) fn rename(
@@ -25,7 +25,7 @@ pub(crate) fn rename(
     position: FilePosition,
     new_name: &str,
 ) -> Option<SourceChange> {
-    let source_file = db.source_file(position.file_id);
+    let source_file = db.parse(position.file_id);
     let syntax = source_file.syntax();
 
     if let Some((ast_name, ast_module)) = find_name_and_module_at_offset(syntax, position) {
diff --git a/crates/ra_ide_api/src/runnables.rs b/crates/ra_ide_api/src/runnables.rs
index 0f9f8deb3..dc8c40ea6 100644
--- a/crates/ra_ide_api/src/runnables.rs
+++ b/crates/ra_ide_api/src/runnables.rs
@@ -3,7 +3,7 @@ use ra_syntax::{
     TextRange, SyntaxNode,
     ast::{self, AstNode, NameOwner, ModuleItemOwner},
 };
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 
 use crate::{db::RootDatabase, FileId};
 
@@ -22,7 +22,7 @@ pub enum RunnableKind {
 }
 
 pub(crate) fn runnables(db: &RootDatabase, file_id: FileId) -> Vec<Runnable> {
-    let source_file = db.source_file(file_id);
+    let source_file = db.parse(file_id);
     source_file
         .syntax()
         .descendants()
diff --git a/crates/ra_ide_api/src/status.rs b/crates/ra_ide_api/src/status.rs
index 717537fcd..e11eed223 100644
--- a/crates/ra_ide_api/src/status.rs
+++ b/crates/ra_ide_api/src/status.rs
@@ -6,7 +6,7 @@ use std::{
 
 use ra_syntax::{AstNode, TreeArc, SourceFile};
 use ra_db::{
-    SourceFileQuery, FileTextQuery, SourceRootId,
+    ParseQuery, FileTextQuery, SourceRootId,
     salsa::{Database, debug::{DebugQueryTable, TableEntry}},
 };
 
@@ -17,7 +17,7 @@ use crate::{
 
 pub(crate) fn status(db: &RootDatabase) -> String {
     let files_stats = db.query(FileTextQuery).entries::<FilesStats>();
-    let syntax_tree_stats = db.query(SourceFileQuery).entries::<SyntaxTreeStats>();
+    let syntax_tree_stats = db.query(ParseQuery).entries::<SyntaxTreeStats>();
     let symbols_stats = db
         .query(LibrarySymbolsQuery)
         .entries::<LibrarySymbolsStats>();
@@ -94,17 +94,12 @@ impl FromIterator<TableEntry<FileId, TreeArc<SourceFile>>> for SyntaxTreeStats {
 #[derive(Default)]
 struct LibrarySymbolsStats {
     total: usize,
-    fst_size: Bytes,
-    symbols_size: Bytes,
+    size: Bytes,
 }
 
 impl fmt::Display for LibrarySymbolsStats {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        write!(
-            fmt,
-            "{} ({} + {}) symbols",
-            self.total, self.fst_size, self.symbols_size
-        )
+        write!(fmt, "{} ({}) symbols", self.total, self.size,)
     }
 }
 
@@ -117,8 +112,7 @@ impl FromIterator<TableEntry<SourceRootId, Arc<SymbolIndex>>> for LibrarySymbols
         for entry in iter {
             let value = entry.value.unwrap();
             res.total += value.len();
-            res.fst_size += value.fst_size();
-            res.symbols_size += value.symbols_size();
+            res.size += value.memory_size();
         }
         res
     }
diff --git a/crates/ra_ide_api/src/symbol_index.rs b/crates/ra_ide_api/src/symbol_index.rs
index 69a669b8d..72c93f530 100644
--- a/crates/ra_ide_api/src/symbol_index.rs
+++ b/crates/ra_ide_api/src/symbol_index.rs
@@ -34,7 +34,7 @@ use ra_syntax::{
     ast::{self, NameOwner},
 };
 use ra_db::{
-    SourceRootId, FilesDatabase,
+    SourceRootId, SourceDatabase,
     salsa::{self, ParallelDatabase},
 };
 use rayon::prelude::*;
@@ -44,16 +44,24 @@ use crate::{
     db::RootDatabase,
 };
 
-#[salsa::query_group]
+#[salsa::query_group(SymbolsDatabaseStorage)]
 pub(crate) trait SymbolsDatabase: hir::db::HirDatabase {
     fn file_symbols(&self, file_id: FileId) -> Arc<SymbolIndex>;
     #[salsa::input]
     fn library_symbols(&self, id: SourceRootId) -> Arc<SymbolIndex>;
+    /// The set of "local" (that is, from the current workspace) roots.
+    /// Files in local roots are assumed to change frequently.
+    #[salsa::input]
+    fn local_roots(&self) -> Arc<Vec<SourceRootId>>;
+    /// The set of roots for crates.io libraries.
+    /// Files in libraries are assumed to never change.
+    #[salsa::input]
+    fn library_roots(&self) -> Arc<Vec<SourceRootId>>;
 }
 
 fn file_symbols(db: &impl SymbolsDatabase, file_id: FileId) -> Arc<SymbolIndex> {
     db.check_canceled();
-    let source_file = db.source_file(file_id);
+    let source_file = db.parse(file_id);
     let mut symbols = source_file
         .syntax()
         .descendants()
@@ -137,12 +145,8 @@ impl SymbolIndex {
         self.symbols.len()
     }
 
-    pub(crate) fn fst_size(&self) -> usize {
-        self.map.as_fst().size()
-    }
-
-    pub(crate) fn symbols_size(&self) -> usize {
-        self.symbols.len() * mem::size_of::<FileSymbol>()
+    pub(crate) fn memory_size(&self) -> usize {
+        self.map.as_fst().size() + self.symbols.len() * mem::size_of::<FileSymbol>()
     }
 
     pub(crate) fn for_files(
diff --git a/crates/ra_ide_api/src/syntax_highlighting.rs b/crates/ra_ide_api/src/syntax_highlighting.rs
index a4d3ad005..26bde495b 100644
--- a/crates/ra_ide_api/src/syntax_highlighting.rs
+++ b/crates/ra_ide_api/src/syntax_highlighting.rs
@@ -1,5 +1,5 @@
 use ra_syntax::{ast, AstNode,};
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 
 use crate::{
     FileId, HighlightedRange,
@@ -7,7 +7,7 @@ use crate::{
 };
 
 pub(crate) fn highlight(db: &RootDatabase, file_id: FileId) -> Vec<HighlightedRange> {
-    let source_file = db.source_file(file_id);
+    let source_file = db.parse(file_id);
     let mut res = ra_ide_api_light::highlight(source_file.syntax());
     for macro_call in source_file
         .syntax()
diff --git a/crates/ra_ide_api_light/src/extend_selection.rs b/crates/ra_ide_api_light/src/extend_selection.rs
index db93db208..f396dfe3f 100644
--- a/crates/ra_ide_api_light/src/extend_selection.rs
+++ b/crates/ra_ide_api_light/src/extend_selection.rs
@@ -9,9 +9,9 @@ pub fn extend_selection(root: &SyntaxNode, range: TextRange) -> Option<TextRange
     let list_kinds = [
         FIELD_PAT_LIST,
         MATCH_ARM_LIST,
-        NAMED_FIELD_LIST,
         NAMED_FIELD_DEF_LIST,
-        POS_FIELD_LIST,
+        POS_FIELD_DEF_LIST,
+        NAMED_FIELD_LIST,
         ENUM_VARIANT_LIST,
         USE_TREE_LIST,
         TYPE_PARAM_LIST,
diff --git a/crates/ra_ide_api_light/src/formatting.rs b/crates/ra_ide_api_light/src/formatting.rs
index ca0fdb928..1f34b85d6 100644
--- a/crates/ra_ide_api_light/src/formatting.rs
+++ b/crates/ra_ide_api_light/src/formatting.rs
@@ -7,9 +7,22 @@ use ra_syntax::{
 
 /// If the node is on the beginning of the line, calculate indent.
 pub(crate) fn leading_indent(node: &SyntaxNode) -> Option<&str> {
-    let prev = prev_leaf(node)?;
-    let ws_text = ast::Whitespace::cast(prev)?.text();
-    ws_text.rfind('\n').map(|pos| &ws_text[pos + 1..])
+    for leaf in prev_leaves(node) {
+        if let Some(ws) = ast::Whitespace::cast(leaf) {
+            let ws_text = ws.text();
+            if let Some(pos) = ws_text.rfind('\n') {
+                return Some(&ws_text[pos + 1..]);
+            }
+        }
+        if leaf.leaf_text().unwrap().contains('\n') {
+            break;
+        }
+    }
+    None
+}
+
+fn prev_leaves(node: &SyntaxNode) -> impl Iterator<Item = &SyntaxNode> {
+    generate(prev_leaf(node), |&node| prev_leaf(node))
 }
 
 fn prev_leaf(node: &SyntaxNode) -> Option<&SyntaxNode> {
diff --git a/crates/ra_ide_api_light/src/snapshots/tests__file_structure.snap b/crates/ra_ide_api_light/src/snapshots/tests__file_structure.snap
index b96398950..270f75a56 100644
--- a/crates/ra_ide_api_light/src/snapshots/tests__file_structure.snap
+++ b/crates/ra_ide_api_light/src/snapshots/tests__file_structure.snap
@@ -1,8 +1,8 @@
 ---
-created: "2019-01-24T18:04:00.090162+00:00"
-creator: insta@0.4.0
+created: "2019-01-26T07:11:02.463391362+00:00"
+creator: insta@0.5.2
 expression: structure
-source: "crates\\ra_ide_api_light\\src\\structure.rs"
+source: crates/ra_ide_api_light/src/structure.rs
 ---
 [
     StructureNode {
@@ -78,6 +78,26 @@ source: "crates\\ra_ide_api_light\\src\\structure.rs"
         detail: None
     },
     StructureNode {
+        parent: Some(
+            6
+        ),
+        label: "X",
+        navigation_range: [169; 170),
+        node_range: [169; 170),
+        kind: ENUM_VARIANT,
+        detail: None
+    },
+    StructureNode {
+        parent: Some(
+            6
+        ),
+        label: "Y",
+        navigation_range: [172; 173),
+        node_range: [172; 178),
+        kind: ENUM_VARIANT,
+        detail: None
+    },
+    StructureNode {
         parent: None,
         label: "T",
         navigation_range: [186; 187),
diff --git a/crates/ra_ide_api_light/src/structure.rs b/crates/ra_ide_api_light/src/structure.rs
index e3713c217..4e080ed03 100644
--- a/crates/ra_ide_api_light/src/structure.rs
+++ b/crates/ra_ide_api_light/src/structure.rs
@@ -103,6 +103,7 @@ fn structure_node(node: &SyntaxNode) -> Option<StructureNode> {
         .visit(decl::<ast::StructDef>)
         .visit(|nfd: &ast::NamedFieldDef| decl_with_type_ref(nfd, nfd.type_ref()))
         .visit(decl::<ast::EnumDef>)
+        .visit(decl::<ast::EnumVariant>)
         .visit(decl::<ast::TraitDef>)
         .visit(decl::<ast::Module>)
         .visit(|td: &ast::TypeDef| decl_with_type_ref(td, td.type_ref()))
diff --git a/crates/ra_ide_api_light/src/typing.rs b/crates/ra_ide_api_light/src/typing.rs
index 5ff2b7c1f..861027b9f 100644
--- a/crates/ra_ide_api_light/src/typing.rs
+++ b/crates/ra_ide_api_light/src/typing.rs
@@ -296,6 +296,46 @@ fn foo() {
     }
 
     #[test]
+    fn indents_middle_of_chain_call() {
+        type_dot(
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                <|>
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                    .
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+        );
+        type_dot(
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                    <|>
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                    .
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+        );
+    }
+
+    #[test]
     fn dont_indent_freestanding_dot() {
         type_dot(
             r"
diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index 165b308d1..00c60ebf3 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -407,7 +407,7 @@ impl<'a, N: AstNode + 'a> Iterator for AstChildren<'a, N> {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum StructFlavor<'a> {
-    Tuple(&'a PosFieldList),
+    Tuple(&'a PosFieldDefList),
     Named(&'a NamedFieldDefList),
     Unit,
 }
@@ -416,7 +416,7 @@ impl StructFlavor<'_> {
     fn from_node<N: AstNode>(node: &N) -> StructFlavor {
         if let Some(nfdl) = child_opt::<_, NamedFieldDefList>(node) {
             StructFlavor::Named(nfdl)
-        } else if let Some(pfl) = child_opt::<_, PosFieldList>(node) {
+        } else if let Some(pfl) = child_opt::<_, PosFieldDefList>(node) {
             StructFlavor::Tuple(pfl)
         } else {
             StructFlavor::Unit
diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index 7da19d782..3ace6533c 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -2248,6 +2248,7 @@ impl ToOwned for NamedFieldDef {
 impl ast::VisibilityOwner for NamedFieldDef {}
 impl ast::NameOwner for NamedFieldDef {}
 impl ast::AttrsOwner for NamedFieldDef {}
+impl ast::DocCommentsOwner for NamedFieldDef {}
 impl NamedFieldDef {
     pub fn type_ref(&self) -> Option<&TypeRef> {
         super::child_opt(self)
@@ -2850,68 +2851,68 @@ impl PointerType {
     }
 }
 
-// PosField
+// PosFieldDef
 #[derive(Debug, PartialEq, Eq, Hash)]
 #[repr(transparent)]
-pub struct PosField {
+pub struct PosFieldDef {
     pub(crate) syntax: SyntaxNode,
 }
-unsafe impl TransparentNewType for PosField {
+unsafe impl TransparentNewType for PosFieldDef {
     type Repr = rowan::SyntaxNode<RaTypes>;
 }
 
-impl AstNode for PosField {
+impl AstNode for PosFieldDef {
     fn cast(syntax: &SyntaxNode) -> Option<&Self> {
         match syntax.kind() {
-            POS_FIELD => Some(PosField::from_repr(syntax.into_repr())),
+            POS_FIELD_DEF => Some(PosFieldDef::from_repr(syntax.into_repr())),
             _ => None,
         }
     }
     fn syntax(&self) -> &SyntaxNode { &self.syntax }
 }
 
-impl ToOwned for PosField {
-    type Owned = TreeArc<PosField>;
-    fn to_owned(&self) -> TreeArc<PosField> { TreeArc::cast(self.syntax.to_owned()) }
+impl ToOwned for PosFieldDef {
+    type Owned = TreeArc<PosFieldDef>;
+    fn to_owned(&self) -> TreeArc<PosFieldDef> { TreeArc::cast(self.syntax.to_owned()) }
 }
 
 
-impl ast::VisibilityOwner for PosField {}
-impl ast::AttrsOwner for PosField {}
-impl PosField {
+impl ast::VisibilityOwner for PosFieldDef {}
+impl ast::AttrsOwner for PosFieldDef {}
+impl PosFieldDef {
     pub fn type_ref(&self) -> Option<&TypeRef> {
         super::child_opt(self)
     }
 }
 
-// PosFieldList
+// PosFieldDefList
 #[derive(Debug, PartialEq, Eq, Hash)]
 #[repr(transparent)]
-pub struct PosFieldList {
+pub struct PosFieldDefList {
     pub(crate) syntax: SyntaxNode,
 }
-unsafe impl TransparentNewType for PosFieldList {
+unsafe impl TransparentNewType for PosFieldDefList {
     type Repr = rowan::SyntaxNode<RaTypes>;
 }
 
-impl AstNode for PosFieldList {
+impl AstNode for PosFieldDefList {
     fn cast(syntax: &SyntaxNode) -> Option<&Self> {
         match syntax.kind() {
-            POS_FIELD_LIST => Some(PosFieldList::from_repr(syntax.into_repr())),
+            POS_FIELD_DEF_LIST => Some(PosFieldDefList::from_repr(syntax.into_repr())),
             _ => None,
         }
     }
     fn syntax(&self) -> &SyntaxNode { &self.syntax }
 }
 
-impl ToOwned for PosFieldList {
-    type Owned = TreeArc<PosFieldList>;
-    fn to_owned(&self) -> TreeArc<PosFieldList> { TreeArc::cast(self.syntax.to_owned()) }
+impl ToOwned for PosFieldDefList {
+    type Owned = TreeArc<PosFieldDefList>;
+    fn to_owned(&self) -> TreeArc<PosFieldDefList> { TreeArc::cast(self.syntax.to_owned()) }
 }
 
 
-impl PosFieldList {
-    pub fn fields(&self) -> impl Iterator<Item = &PosField> {
+impl PosFieldDefList {
+    pub fn fields(&self) -> impl Iterator<Item = &PosFieldDef> {
         super::children(self)
     }
 }
diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index cb5d6cde8..85fc79038 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -205,8 +205,8 @@ Grammar(
         "ENUM_VARIANT",
         "NAMED_FIELD_DEF_LIST",
         "NAMED_FIELD_DEF",
-        "POS_FIELD_LIST",
-        "POS_FIELD",
+        "POS_FIELD_DEF_LIST",
+        "POS_FIELD_DEF",
         "ENUM_VARIANT_LIST",
         "ITEM_LIST",
         "ATTR",
@@ -268,9 +268,9 @@ Grammar(
             ]
         ),
         "NamedFieldDefList": (collections: [["fields", "NamedFieldDef"]]),
-        "NamedFieldDef": ( traits: ["VisibilityOwner", "NameOwner", "AttrsOwner"], options: ["TypeRef"] ),
-        "PosFieldList": (collections: [["fields", "PosField"]]),
-        "PosField": ( traits: ["VisibilityOwner", "AttrsOwner"], options: ["TypeRef"]),
+        "NamedFieldDef": ( traits: ["VisibilityOwner", "NameOwner", "AttrsOwner", "DocCommentsOwner"], options: ["TypeRef"] ),
+        "PosFieldDefList": (collections: [["fields", "PosFieldDef"]]),
+        "PosFieldDef": ( traits: ["VisibilityOwner", "AttrsOwner"], options: ["TypeRef"]),
         "EnumDef": ( traits: [
             "VisibilityOwner",
             "NameOwner",
diff --git a/crates/ra_syntax/src/grammar/items/nominal.rs b/crates/ra_syntax/src/grammar/items/nominal.rs
index 0784fb7b1..ff9b38f9c 100644
--- a/crates/ra_syntax/src/grammar/items/nominal.rs
+++ b/crates/ra_syntax/src/grammar/items/nominal.rs
@@ -28,7 +28,7 @@ pub(super) fn struct_def(p: &mut Parser, kind: SyntaxKind) {
         }
         L_CURLY => named_field_def_list(p),
         L_PAREN if kind == STRUCT_KW => {
-            pos_field_list(p);
+            pos_field_def_list(p);
             // test tuple_struct_where
             // struct Test<T>(T) where T: Clone;
             // struct Test<T>(T);
@@ -74,7 +74,7 @@ pub(crate) fn enum_variant_list(p: &mut Parser) {
             name(p);
             match p.current() {
                 L_CURLY => named_field_def_list(p),
-                L_PAREN => pos_field_list(p),
+                L_PAREN => pos_field_def_list(p),
                 EQ => {
                     p.bump();
                     expressions::expr(p);
@@ -132,7 +132,7 @@ pub(crate) fn named_field_def_list(p: &mut Parser) {
     }
 }
 
-fn pos_field_list(p: &mut Parser) {
+fn pos_field_def_list(p: &mut Parser) {
     assert!(p.at(L_PAREN));
     let m = p.start();
     if !p.expect(L_PAREN) {
@@ -157,12 +157,12 @@ fn pos_field_list(p: &mut Parser) {
             break;
         }
         types::type_(p);
-        m.complete(p, POS_FIELD);
+        m.complete(p, POS_FIELD_DEF);
 
         if !p.at(R_PAREN) {
             p.expect(COMMA);
         }
     }
     p.expect(R_PAREN);
-    m.complete(p, POS_FIELD_LIST);
+    m.complete(p, POS_FIELD_DEF_LIST);
 }
diff --git a/crates/ra_syntax/src/parser_impl/event.rs b/crates/ra_syntax/src/parser_impl/event.rs
index bd77fee89..33e10ef85 100644
--- a/crates/ra_syntax/src/parser_impl/event.rs
+++ b/crates/ra_syntax/src/parser_impl/event.rs
@@ -250,7 +250,7 @@ fn n_attached_trivias<'a>(
 ) -> usize {
     match kind {
         CONST_DEF | TYPE_DEF | STRUCT_DEF | ENUM_DEF | ENUM_VARIANT | FN_DEF | TRAIT_DEF
-        | MODULE => {
+        | MODULE | NAMED_FIELD_DEF => {
             let mut res = 0;
             for (i, (kind, text)) in trivias.enumerate() {
                 match kind {
diff --git a/crates/ra_syntax/src/syntax_kinds/generated.rs b/crates/ra_syntax/src/syntax_kinds/generated.rs
index 06faf7557..14f610891 100644
--- a/crates/ra_syntax/src/syntax_kinds/generated.rs
+++ b/crates/ra_syntax/src/syntax_kinds/generated.rs
@@ -195,8 +195,8 @@ pub enum SyntaxKind {
     ENUM_VARIANT,
     NAMED_FIELD_DEF_LIST,
     NAMED_FIELD_DEF,
-    POS_FIELD_LIST,
-    POS_FIELD,
+    POS_FIELD_DEF_LIST,
+    POS_FIELD_DEF,
     ENUM_VARIANT_LIST,
     ITEM_LIST,
     ATTR,
@@ -458,8 +458,8 @@ impl SyntaxKind {
             ENUM_VARIANT => &SyntaxInfo { name: "ENUM_VARIANT" },
             NAMED_FIELD_DEF_LIST => &SyntaxInfo { name: "NAMED_FIELD_DEF_LIST" },
             NAMED_FIELD_DEF => &SyntaxInfo { name: "NAMED_FIELD_DEF" },
-            POS_FIELD_LIST => &SyntaxInfo { name: "POS_FIELD_LIST" },
-            POS_FIELD => &SyntaxInfo { name: "POS_FIELD" },
+            POS_FIELD_DEF_LIST => &SyntaxInfo { name: "POS_FIELD_DEF_LIST" },
+            POS_FIELD_DEF => &SyntaxInfo { name: "POS_FIELD_DEF" },
             ENUM_VARIANT_LIST => &SyntaxInfo { name: "ENUM_VARIANT_LIST" },
             ITEM_LIST => &SyntaxInfo { name: "ITEM_LIST" },
             ATTR => &SyntaxInfo { name: "ATTR" },
diff --git a/crates/ra_syntax/tests/data/parser/err/0013_invalid_type.txt b/crates/ra_syntax/tests/data/parser/err/0013_invalid_type.txt
index 83d716b2f..1ec15194c 100644
--- a/crates/ra_syntax/tests/data/parser/err/0013_invalid_type.txt
+++ b/crates/ra_syntax/tests/data/parser/err/0013_invalid_type.txt
@@ -7,10 +7,10 @@ SOURCE_FILE@[0; 86)
     WHITESPACE@[10; 11)
     NAME@[11; 16)
       IDENT@[11; 16) "Cache"
-    POS_FIELD_LIST@[16; 72)
+    POS_FIELD_DEF_LIST@[16; 72)
       L_PAREN@[16; 17)
       WHITESPACE@[17; 22)
-      POS_FIELD@[22; 68)
+      POS_FIELD_DEF@[22; 68)
         PATH_TYPE@[22; 68)
           PATH@[22; 68)
             PATH_SEGMENT@[22; 68)
@@ -55,7 +55,7 @@ SOURCE_FILE@[0; 86)
                                         err: `expected R_ANGLE`
                                         err: `expected COMMA`
       WHITESPACE@[68; 69)
-      POS_FIELD@[69; 72)
+      POS_FIELD_DEF@[69; 72)
         PATH_TYPE@[69; 72)
           PATH@[69; 72)
             PATH_SEGMENT@[69; 72)
diff --git a/crates/ra_syntax/tests/data/parser/err/0025_nope.txt b/crates/ra_syntax/tests/data/parser/err/0025_nope.txt
index 615064f77..e0824ca56 100644
--- a/crates/ra_syntax/tests/data/parser/err/0025_nope.txt
+++ b/crates/ra_syntax/tests/data/parser/err/0025_nope.txt
@@ -28,9 +28,9 @@ SOURCE_FILE@[0; 575)
           ENUM_VARIANT@[50; 62)
             NAME@[50; 54)
               IDENT@[50; 54) "Var2"
-            POS_FIELD_LIST@[54; 62)
+            POS_FIELD_DEF_LIST@[54; 62)
               L_PAREN@[54; 55)
-              POS_FIELD@[55; 61)
+              POS_FIELD_DEF@[55; 61)
                 PATH_TYPE@[55; 61)
                   PATH@[55; 61)
                     PATH_SEGMENT@[55; 61)
@@ -151,9 +151,9 @@ SOURCE_FILE@[0; 575)
                 ENUM_VARIANT@[363; 372)
                   NAME@[363; 367)
                     IDENT@[363; 367) "Nope"
-                  POS_FIELD_LIST@[367; 372)
+                  POS_FIELD_DEF_LIST@[367; 372)
                     L_PAREN@[367; 368)
-                    POS_FIELD@[368; 371)
+                    POS_FIELD_DEF@[368; 371)
                       PATH_TYPE@[368; 371)
                         PATH@[368; 371)
                           PATH_SEGMENT@[368; 371)
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0083_struct_items.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0083_struct_items.txt
index 058639375..6247729f6 100644
--- a/crates/ra_syntax/tests/data/parser/inline/ok/0083_struct_items.txt
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0083_struct_items.txt
@@ -21,7 +21,7 @@ SOURCE_FILE@[0; 106)
     WHITESPACE@[32; 33)
     NAME@[33; 36)
       IDENT@[33; 36) "Foo"
-    POS_FIELD_LIST@[36; 38)
+    POS_FIELD_DEF_LIST@[36; 38)
       L_PAREN@[36; 37)
       R_PAREN@[37; 38)
     SEMI@[38; 39)
@@ -31,9 +31,9 @@ SOURCE_FILE@[0; 106)
     WHITESPACE@[46; 47)
     NAME@[47; 50)
       IDENT@[47; 50) "Foo"
-    POS_FIELD_LIST@[50; 65)
+    POS_FIELD_DEF_LIST@[50; 65)
       L_PAREN@[50; 51)
-      POS_FIELD@[51; 57)
+      POS_FIELD_DEF@[51; 57)
         PATH_TYPE@[51; 57)
           PATH@[51; 57)
             PATH_SEGMENT@[51; 57)
@@ -41,7 +41,7 @@ SOURCE_FILE@[0; 106)
                 IDENT@[51; 57) "String"
       COMMA@[57; 58)
       WHITESPACE@[58; 59)
-      POS_FIELD@[59; 64)
+      POS_FIELD_DEF@[59; 64)
         PATH_TYPE@[59; 64)
           PATH@[59; 64)
             PATH_SEGMENT@[59; 64)
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0114_tuple_struct_where.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0114_tuple_struct_where.txt
index b7de83072..4f439f21c 100644
--- a/crates/ra_syntax/tests/data/parser/inline/ok/0114_tuple_struct_where.txt
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0114_tuple_struct_where.txt
@@ -10,9 +10,9 @@ SOURCE_FILE@[0; 53)
         NAME@[12; 13)
           IDENT@[12; 13) "T"
       R_ANGLE@[13; 14)
-    POS_FIELD_LIST@[14; 17)
+    POS_FIELD_DEF_LIST@[14; 17)
       L_PAREN@[14; 15)
-      POS_FIELD@[15; 16)
+      POS_FIELD_DEF@[15; 16)
         PATH_TYPE@[15; 16)
           PATH@[15; 16)
             PATH_SEGMENT@[15; 16)
@@ -49,9 +49,9 @@ SOURCE_FILE@[0; 53)
         NAME@[46; 47)
           IDENT@[46; 47) "T"
       R_ANGLE@[47; 48)
-    POS_FIELD_LIST@[48; 51)
+    POS_FIELD_DEF_LIST@[48; 51)
       L_PAREN@[48; 49)
-      POS_FIELD@[49; 50)
+      POS_FIELD_DEF@[49; 50)
         PATH_TYPE@[49; 50)
           PATH@[49; 50)
             PATH_SEGMENT@[49; 50)
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0115_pos_field_attrs.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0115_pos_field_attrs.txt
index 99ec0755b..4da84ba48 100644
--- a/crates/ra_syntax/tests/data/parser/inline/ok/0115_pos_field_attrs.txt
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0115_pos_field_attrs.txt
@@ -5,10 +5,10 @@ SOURCE_FILE@[0; 60)
     NAME@[7; 8)
       IDENT@[7; 8) "S"
     WHITESPACE@[8; 9)
-    POS_FIELD_LIST@[9; 58)
+    POS_FIELD_DEF_LIST@[9; 58)
       L_PAREN@[9; 10)
       WHITESPACE@[10; 15)
-      POS_FIELD@[15; 55)
+      POS_FIELD_DEF@[15; 55)
         ATTR@[15; 43)
           POUND@[15; 16)
           TOKEN_TREE@[16; 43)
diff --git a/crates/ra_syntax/tests/data/parser/ok/0016_struct_flavors.txt b/crates/ra_syntax/tests/data/parser/ok/0016_struct_flavors.txt
index 1d355823d..d021d6de6 100644
--- a/crates/ra_syntax/tests/data/parser/ok/0016_struct_flavors.txt
+++ b/crates/ra_syntax/tests/data/parser/ok/0016_struct_flavors.txt
@@ -21,7 +21,7 @@ SOURCE_FILE@[0; 97)
     WHITESPACE@[28; 29)
     NAME@[29; 30)
       IDENT@[29; 30) "C"
-    POS_FIELD_LIST@[30; 32)
+    POS_FIELD_DEF_LIST@[30; 32)
       L_PAREN@[30; 31)
       R_PAREN@[31; 32)
     SEMI@[32; 33)
@@ -68,9 +68,9 @@ SOURCE_FILE@[0; 97)
     WHITESPACE@[82; 83)
     NAME@[83; 84)
       IDENT@[83; 84) "E"
-    POS_FIELD_LIST@[84; 95)
+    POS_FIELD_DEF_LIST@[84; 95)
       L_PAREN@[84; 85)
-      POS_FIELD@[85; 90)
+      POS_FIELD_DEF@[85; 90)
         VISIBILITY@[85; 88)
           PUB_KW@[85; 88)
         WHITESPACE@[88; 89)
@@ -81,7 +81,7 @@ SOURCE_FILE@[0; 97)
                 IDENT@[89; 90) "x"
       COMMA@[90; 91)
       WHITESPACE@[91; 92)
-      POS_FIELD@[92; 93)
+      POS_FIELD_DEF@[92; 93)
         PATH_TYPE@[92; 93)
           PATH@[92; 93)
             PATH_SEGMENT@[92; 93)
diff --git a/crates/ra_syntax/tests/data/parser/ok/0018_struct_type_params.txt b/crates/ra_syntax/tests/data/parser/ok/0018_struct_type_params.txt
index 491d154df..05480c81b 100644
--- a/crates/ra_syntax/tests/data/parser/ok/0018_struct_type_params.txt
+++ b/crates/ra_syntax/tests/data/parser/ok/0018_struct_type_params.txt
@@ -23,9 +23,9 @@ SOURCE_FILE@[0; 290)
         NAME@[24; 25)
           IDENT@[24; 25) "T"
       R_ANGLE@[25; 26)
-    POS_FIELD_LIST@[26; 31)
+    POS_FIELD_DEF_LIST@[26; 31)
       L_PAREN@[26; 27)
-      POS_FIELD@[27; 30)
+      POS_FIELD_DEF@[27; 30)
         PATH_TYPE@[27; 30)
           PATH@[27; 30)
             PATH_SEGMENT@[27; 30)
diff --git a/crates/ra_syntax/tests/data/parser/ok/0019_enums.txt b/crates/ra_syntax/tests/data/parser/ok/0019_enums.txt
index 6925219e8..2ac55cfbc 100644
--- a/crates/ra_syntax/tests/data/parser/ok/0019_enums.txt
+++ b/crates/ra_syntax/tests/data/parser/ok/0019_enums.txt
@@ -131,9 +131,9 @@ SOURCE_FILE@[0; 182)
       ENUM_VARIANT@[162; 169)
         NAME@[162; 163)
           IDENT@[162; 163) "D"
-        POS_FIELD_LIST@[163; 169)
+        POS_FIELD_DEF_LIST@[163; 169)
           L_PAREN@[163; 164)
-          POS_FIELD@[164; 167)
+          POS_FIELD_DEF@[164; 167)
             PATH_TYPE@[164; 167)
               PATH@[164; 167)
                 PATH_SEGMENT@[164; 167)
@@ -146,7 +146,7 @@ SOURCE_FILE@[0; 182)
       ENUM_VARIANT@[175; 178)
         NAME@[175; 176)
           IDENT@[175; 176) "E"
-        POS_FIELD_LIST@[176; 178)
+        POS_FIELD_DEF_LIST@[176; 178)
           L_PAREN@[176; 177)
           R_PAREN@[177; 178)
       COMMA@[178; 179)
diff --git a/crates/ra_vfs/Cargo.toml b/crates/ra_vfs/Cargo.toml
index e637063c9..383381d2a 100644
--- a/crates/ra_vfs/Cargo.toml
+++ b/crates/ra_vfs/Cargo.toml
@@ -10,9 +10,13 @@ relative-path = "0.4.0"
 rustc-hash = "1.0"
 crossbeam-channel = "0.3.5"
 log = "0.4.6"
+notify = "4.0.7"
+drop_bomb = "0.1.0"
+parking_lot = "0.7.0"
 
 thread_worker = { path = "../thread_worker" }
 ra_arena = { path = "../ra_arena" }
 
 [dev-dependencies]
 tempfile = "3"
+flexi_logger = "0.10.0"
diff --git a/crates/ra_vfs/src/io.rs b/crates/ra_vfs/src/io.rs
index 80328ad18..7ca1e9835 100644
--- a/crates/ra_vfs/src/io.rs
+++ b/crates/ra_vfs/src/io.rs
@@ -1,55 +1,109 @@
-use std::{
-    fmt,
-    fs,
-    path::{Path, PathBuf},
-};
+use std::{fs, sync::Arc, thread};
 
-use walkdir::{DirEntry, WalkDir};
-use thread_worker::{WorkerHandle};
+use crossbeam_channel::{Receiver, Sender};
 use relative_path::RelativePathBuf;
+use thread_worker::WorkerHandle;
+use walkdir::WalkDir;
 
-use crate::{VfsRoot, has_rs_extension};
+mod watcher;
+use watcher::Watcher;
 
-pub(crate) struct Task {
-    pub(crate) root: VfsRoot,
-    pub(crate) path: PathBuf,
-    pub(crate) filter: Box<Fn(&DirEntry) -> bool + Send>,
+use crate::{RootFilter, Roots, VfsRoot};
+
+pub(crate) enum Task {
+    AddRoot {
+        root: VfsRoot,
+        filter: Arc<RootFilter>,
+    },
 }
 
-pub struct TaskResult {
-    pub(crate) root: VfsRoot,
-    pub(crate) files: Vec<(RelativePathBuf, String)>,
+#[derive(Debug)]
+pub enum TaskResult {
+    BulkLoadRoot {
+        root: VfsRoot,
+        files: Vec<(RelativePathBuf, String)>,
+    },
+    AddSingleFile {
+        root: VfsRoot,
+        path: RelativePathBuf,
+        text: String,
+    },
+    ChangeSingleFile {
+        root: VfsRoot,
+        path: RelativePathBuf,
+        text: String,
+    },
+    RemoveSingleFile {
+        root: VfsRoot,
+        path: RelativePathBuf,
+    },
 }
 
-impl fmt::Debug for TaskResult {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.write_str("TaskResult { ... }")
-    }
+pub(crate) struct Worker {
+    worker: thread_worker::Worker<Task, TaskResult>,
+    worker_handle: WorkerHandle,
 }
 
-pub(crate) type Worker = thread_worker::Worker<Task, TaskResult>;
+impl Worker {
+    pub(crate) fn start(roots: Arc<Roots>) -> Worker {
+        let (worker, worker_handle) =
+            thread_worker::spawn("vfs", 128, move |input_receiver, output_sender| {
+                let mut watcher = match Watcher::start(roots, output_sender.clone()) {
+                    Ok(w) => Some(w),
+                    Err(e) => {
+                        log::error!("could not start watcher: {}", e);
+                        None
+                    }
+                };
+                let res = input_receiver
+                    .into_iter()
+                    .filter_map(|t| handle_task(t, &mut watcher))
+                    .try_for_each(|it| output_sender.send(it));
+                if let Some(watcher) = watcher {
+                    let _ = watcher.shutdown();
+                }
+                res.unwrap()
+            });
+        Worker {
+            worker,
+            worker_handle,
+        }
+    }
+
+    pub(crate) fn sender(&self) -> &Sender<Task> {
+        &self.worker.inp
+    }
+
+    pub(crate) fn receiver(&self) -> &Receiver<TaskResult> {
+        &self.worker.out
+    }
 
-pub(crate) fn start() -> (Worker, WorkerHandle) {
-    thread_worker::spawn("vfs", 128, |input_receiver, output_sender| {
-        input_receiver
-            .into_iter()
-            .map(handle_task)
-            .try_for_each(|it| output_sender.send(it))
-            .unwrap()
-    })
+    pub(crate) fn shutdown(self) -> thread::Result<()> {
+        let _ = self.worker.shutdown();
+        self.worker_handle.shutdown()
+    }
 }
 
-fn handle_task(task: Task) -> TaskResult {
-    let Task { root, path, filter } = task;
-    log::debug!("loading {} ...", path.as_path().display());
-    let files = load_root(path.as_path(), &*filter);
-    log::debug!("... loaded {}", path.as_path().display());
-    TaskResult { root, files }
+fn handle_task(task: Task, watcher: &mut Option<Watcher>) -> Option<TaskResult> {
+    match task {
+        Task::AddRoot { root, filter } => {
+            if let Some(watcher) = watcher {
+                watcher.watch_root(&filter)
+            }
+            log::debug!("loading {} ...", filter.root.as_path().display());
+            let files = load_root(filter.as_ref());
+            log::debug!("... loaded {}", filter.root.as_path().display());
+            Some(TaskResult::BulkLoadRoot { root, files })
+        }
+    }
 }
 
-fn load_root(root: &Path, filter: &dyn Fn(&DirEntry) -> bool) -> Vec<(RelativePathBuf, String)> {
+fn load_root(filter: &RootFilter) -> Vec<(RelativePathBuf, String)> {
     let mut res = Vec::new();
-    for entry in WalkDir::new(root).into_iter().filter_entry(filter) {
+    for entry in WalkDir::new(&filter.root)
+        .into_iter()
+        .filter_entry(filter.entry_filter())
+    {
         let entry = match entry {
             Ok(entry) => entry,
             Err(e) => {
@@ -61,9 +115,6 @@ fn load_root(root: &Path, filter: &dyn Fn(&DirEntry) -> bool) -> Vec<(RelativePa
             continue;
         }
         let path = entry.path();
-        if !has_rs_extension(path) {
-            continue;
-        }
         let text = match fs::read_to_string(path) {
             Ok(text) => text,
             Err(e) => {
@@ -71,7 +122,7 @@ fn load_root(root: &Path, filter: &dyn Fn(&DirEntry) -> bool) -> Vec<(RelativePa
                 continue;
             }
         };
-        let path = RelativePathBuf::from_path(path.strip_prefix(root).unwrap()).unwrap();
+        let path = RelativePathBuf::from_path(path.strip_prefix(&filter.root).unwrap()).unwrap();
         res.push((path.to_owned(), text))
     }
     res
diff --git a/crates/ra_vfs/src/io/watcher.rs b/crates/ra_vfs/src/io/watcher.rs
new file mode 100644
index 000000000..ff6775f59
--- /dev/null
+++ b/crates/ra_vfs/src/io/watcher.rs
@@ -0,0 +1,200 @@
+use crate::{io, RootFilter, Roots, VfsRoot};
+use crossbeam_channel::Sender;
+use drop_bomb::DropBomb;
+use notify::{DebouncedEvent, RecommendedWatcher, RecursiveMode, Watcher as NotifyWatcher};
+use parking_lot::Mutex;
+use std::{
+    fs,
+    path::{Path, PathBuf},
+    sync::{mpsc, Arc},
+    thread,
+    time::Duration,
+};
+use walkdir::WalkDir;
+
+#[derive(Debug)]
+enum ChangeKind {
+    Create,
+    Write,
+    Remove,
+}
+
+const WATCHER_DELAY: Duration = Duration::from_millis(250);
+
+pub(crate) struct Watcher {
+    thread: thread::JoinHandle<()>,
+    bomb: DropBomb,
+    watcher: Arc<Mutex<Option<RecommendedWatcher>>>,
+}
+
+impl Watcher {
+    pub(crate) fn start(
+        roots: Arc<Roots>,
+        output_sender: Sender<io::TaskResult>,
+    ) -> Result<Watcher, Box<std::error::Error>> {
+        let (input_sender, input_receiver) = mpsc::channel();
+        let watcher = Arc::new(Mutex::new(Some(notify::watcher(
+            input_sender,
+            WATCHER_DELAY,
+        )?)));
+        let sender = output_sender.clone();
+        let watcher_clone = watcher.clone();
+        let thread = thread::spawn(move || {
+            let worker = WatcherWorker {
+                roots,
+                watcher: watcher_clone,
+                sender,
+            };
+            input_receiver
+                .into_iter()
+                // forward relevant events only
+                .try_for_each(|change| worker.handle_debounced_event(change))
+                .unwrap()
+        });
+        Ok(Watcher {
+            thread,
+            watcher,
+            bomb: DropBomb::new(format!("Watcher was not shutdown")),
+        })
+    }
+
+    pub fn watch_root(&mut self, filter: &RootFilter) {
+        for res in WalkDir::new(&filter.root)
+            .into_iter()
+            .filter_entry(filter.entry_filter())
+        {
+            match res {
+                Ok(entry) => {
+                    if entry.file_type().is_dir() {
+                        watch_one(self.watcher.as_ref(), entry.path());
+                    }
+                }
+                Err(e) => log::warn!("watcher error: {}", e),
+            }
+        }
+    }
+
+    pub fn shutdown(mut self) -> thread::Result<()> {
+        self.bomb.defuse();
+        drop(self.watcher.lock().take());
+        let res = self.thread.join();
+        match &res {
+            Ok(()) => log::info!("... Watcher terminated with ok"),
+            Err(_) => log::error!("... Watcher terminated with err"),
+        }
+        res
+    }
+}
+
+struct WatcherWorker {
+    watcher: Arc<Mutex<Option<RecommendedWatcher>>>,
+    roots: Arc<Roots>,
+    sender: Sender<io::TaskResult>,
+}
+
+impl WatcherWorker {
+    fn handle_debounced_event(&self, ev: DebouncedEvent) -> Result<(), Box<std::error::Error>> {
+        match ev {
+            DebouncedEvent::NoticeWrite(_)
+            | DebouncedEvent::NoticeRemove(_)
+            | DebouncedEvent::Chmod(_) => {
+                // ignore
+            }
+            DebouncedEvent::Rescan => {
+                // TODO rescan all roots
+            }
+            DebouncedEvent::Create(path) => {
+                self.handle_change(path, ChangeKind::Create);
+            }
+            DebouncedEvent::Write(path) => {
+                self.handle_change(path, ChangeKind::Write);
+            }
+            DebouncedEvent::Remove(path) => {
+                self.handle_change(path, ChangeKind::Remove);
+            }
+            DebouncedEvent::Rename(src, dst) => {
+                self.handle_change(src, ChangeKind::Remove);
+                self.handle_change(dst, ChangeKind::Create);
+            }
+            DebouncedEvent::Error(err, path) => {
+                // TODO should we reload the file contents?
+                log::warn!("watcher error \"{}\", {:?}", err, path);
+            }
+        }
+        Ok(())
+    }
+
+    fn handle_change(&self, path: PathBuf, kind: ChangeKind) {
+        if let Err(e) = self.try_handle_change(path, kind) {
+            log::warn!("watcher error: {}", e)
+        }
+    }
+
+    fn try_handle_change(
+        &self,
+        path: PathBuf,
+        kind: ChangeKind,
+    ) -> Result<(), Box<std::error::Error>> {
+        let (root, rel_path) = match self.roots.find(&path) {
+            Some(x) => x,
+            None => return Ok(()),
+        };
+        match kind {
+            ChangeKind::Create => {
+                if path.is_dir() {
+                    self.watch_recursive(&path, root);
+                } else {
+                    let text = fs::read_to_string(&path)?;
+                    self.sender.send(io::TaskResult::AddSingleFile {
+                        root,
+                        path: rel_path,
+                        text,
+                    })?
+                }
+            }
+            ChangeKind::Write => {
+                let text = fs::read_to_string(&path)?;
+                self.sender.send(io::TaskResult::ChangeSingleFile {
+                    root,
+                    path: rel_path,
+                    text,
+                })?
+            }
+            ChangeKind::Remove => self.sender.send(io::TaskResult::RemoveSingleFile {
+                root,
+                path: rel_path,
+            })?,
+        }
+        Ok(())
+    }
+
+    fn watch_recursive(&self, dir: &Path, root: VfsRoot) {
+        let filter = &self.roots[root];
+        for res in WalkDir::new(dir)
+            .into_iter()
+            .filter_entry(filter.entry_filter())
+        {
+            match res {
+                Ok(entry) => {
+                    if entry.file_type().is_dir() {
+                        watch_one(self.watcher.as_ref(), entry.path());
+                    } else {
+                        // emit only for files otherwise we will cause watch_recursive to be called again with a dir that we are already watching
+                        // emit as create because we haven't seen it yet
+                        self.handle_change(entry.path().to_path_buf(), ChangeKind::Create);
+                    }
+                }
+                Err(e) => log::warn!("watcher error: {}", e),
+            }
+        }
+    }
+}
+
+fn watch_one(watcher: &Mutex<Option<RecommendedWatcher>>, dir: &Path) {
+    if let Some(watcher) = watcher.lock().as_mut() {
+        match watcher.watch(dir, RecursiveMode::NonRecursive) {
+            Ok(()) => log::debug!("watching \"{}\"", dir.display()),
+            Err(e) => log::warn!("could not watch \"{}\": {}", dir.display(), e),
+        }
+    }
+}
diff --git a/crates/ra_vfs/src/lib.rs b/crates/ra_vfs/src/lib.rs
index cdea18d73..d1b0222e7 100644
--- a/crates/ra_vfs/src/lib.rs
+++ b/crates/ra_vfs/src/lib.rs
@@ -16,52 +16,77 @@
 mod io;
 
 use std::{
-    fmt,
-    mem,
-    thread,
     cmp::Reverse,
+    fmt, fs, mem,
+    ops::{Deref, DerefMut},
     path::{Path, PathBuf},
-    ffi::OsStr,
     sync::Arc,
-    fs,
+    thread,
 };
 
-use rustc_hash::{FxHashMap, FxHashSet};
-use relative_path::RelativePathBuf;
 use crossbeam_channel::Receiver;
+use ra_arena::{impl_arena_id, Arena, RawId};
+use relative_path::{Component, RelativePath, RelativePathBuf};
+use rustc_hash::{FxHashMap, FxHashSet};
 use walkdir::DirEntry;
-use thread_worker::WorkerHandle;
-use ra_arena::{Arena, RawId, impl_arena_id};
 
 pub use crate::io::TaskResult as VfsTask;
+use io::{TaskResult, Worker};
 
 /// `RootFilter` is a predicate that checks if a file can belong to a root. If
 /// several filters match a file (nested dirs), the most nested one wins.
-struct RootFilter {
+pub(crate) struct RootFilter {
     root: PathBuf,
-    file_filter: fn(&Path) -> bool,
+    filter: fn(&Path, &RelativePath) -> bool,
+    excluded_dirs: Vec<PathBuf>,
 }
 
 impl RootFilter {
-    fn new(root: PathBuf) -> RootFilter {
+    fn new(root: PathBuf, excluded_dirs: Vec<PathBuf>) -> RootFilter {
         RootFilter {
             root,
-            file_filter: has_rs_extension,
+            filter: default_filter,
+            excluded_dirs,
         }
     }
     /// Check if this root can contain `path`. NB: even if this returns
     /// true, the `path` might actually be conained in some nested root.
-    fn can_contain(&self, path: &Path) -> Option<RelativePathBuf> {
-        if !(self.file_filter)(path) {
+    pub(crate) fn can_contain(&self, path: &Path) -> Option<RelativePathBuf> {
+        let rel_path = path.strip_prefix(&self.root).ok()?;
+        let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
+        if !(self.filter)(path, rel_path.as_relative_path()) {
             return None;
         }
-        let path = path.strip_prefix(&self.root).ok()?;
-        RelativePathBuf::from_path(path).ok()
+        Some(rel_path)
+    }
+
+    pub(crate) fn entry_filter<'a>(&'a self) -> impl FnMut(&DirEntry) -> bool + 'a {
+        move |entry: &DirEntry| {
+            if entry.file_type().is_dir() && self.excluded_dirs.iter().any(|it| it == entry.path())
+            {
+                // do not walk nested roots
+                false
+            } else {
+                self.can_contain(entry.path()).is_some()
+            }
+        }
     }
 }
 
-fn has_rs_extension(p: &Path) -> bool {
-    p.extension() == Some(OsStr::new("rs"))
+pub(crate) fn default_filter(path: &Path, rel_path: &RelativePath) -> bool {
+    if path.is_dir() {
+        for (i, c) in rel_path.components().enumerate() {
+            if let Component::Normal(c) = c {
+                // TODO hardcoded for now
+                if (i == 0 && c == "target") || c == ".git" || c == "node_modules" {
+                    return false;
+                }
+            }
+        }
+        true
+    } else {
+        rel_path.extension() == Some("rs")
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -75,16 +100,58 @@ impl_arena_id!(VfsFile);
 struct VfsFileData {
     root: VfsRoot,
     path: RelativePathBuf,
+    is_overlayed: bool,
     text: Arc<String>,
 }
 
+pub(crate) struct Roots {
+    roots: Arena<VfsRoot, Arc<RootFilter>>,
+}
+
+impl Roots {
+    pub(crate) fn new(mut paths: Vec<PathBuf>) -> Roots {
+        let mut roots = Arena::default();
+        // A hack to make nesting work.
+        paths.sort_by_key(|it| Reverse(it.as_os_str().len()));
+        for (i, path) in paths.iter().enumerate() {
+            let nested_roots = paths[..i]
+                .iter()
+                .filter(|it| it.starts_with(path))
+                .map(|it| it.clone())
+                .collect::<Vec<_>>();
+
+            let root_filter = Arc::new(RootFilter::new(path.clone(), nested_roots));
+
+            roots.alloc(root_filter.clone());
+        }
+        Roots { roots }
+    }
+    pub(crate) fn find(&self, path: &Path) -> Option<(VfsRoot, RelativePathBuf)> {
+        self.roots
+            .iter()
+            .find_map(|(root, data)| data.can_contain(path).map(|it| (root, it)))
+    }
+}
+
+impl Deref for Roots {
+    type Target = Arena<VfsRoot, Arc<RootFilter>>;
+    fn deref(&self) -> &Self::Target {
+        &self.roots
+    }
+}
+
+impl DerefMut for Roots {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.roots
+    }
+}
+
 pub struct Vfs {
-    roots: Arena<VfsRoot, RootFilter>,
+    roots: Arc<Roots>,
     files: Arena<VfsFile, VfsFileData>,
     root2files: FxHashMap<VfsRoot, FxHashSet<VfsFile>>,
     pending_changes: Vec<VfsChange>,
-    worker: io::Worker,
-    worker_handle: WorkerHandle,
+    worker: Worker,
 }
 
 impl fmt::Debug for Vfs {
@@ -94,44 +161,30 @@ impl fmt::Debug for Vfs {
 }
 
 impl Vfs {
-    pub fn new(mut roots: Vec<PathBuf>) -> (Vfs, Vec<VfsRoot>) {
-        let (worker, worker_handle) = io::start();
-
-        let mut res = Vfs {
-            roots: Arena::default(),
+    pub fn new(roots: Vec<PathBuf>) -> (Vfs, Vec<VfsRoot>) {
+        let roots = Arc::new(Roots::new(roots));
+        let worker = io::Worker::start(roots.clone());
+        let mut root2files = FxHashMap::default();
+
+        for (root, filter) in roots.iter() {
+            root2files.insert(root, Default::default());
+            worker
+                .sender()
+                .send(io::Task::AddRoot {
+                    root,
+                    filter: filter.clone(),
+                })
+                .unwrap();
+        }
+        let res = Vfs {
+            roots,
             files: Arena::default(),
-            root2files: FxHashMap::default(),
+            root2files,
             worker,
-            worker_handle,
             pending_changes: Vec::new(),
         };
-
-        // A hack to make nesting work.
-        roots.sort_by_key(|it| Reverse(it.as_os_str().len()));
-        for (i, path) in roots.iter().enumerate() {
-            let root = res.roots.alloc(RootFilter::new(path.clone()));
-            res.root2files.insert(root, Default::default());
-            let nested = roots[..i]
-                .iter()
-                .filter(|it| it.starts_with(path))
-                .map(|it| it.clone())
-                .collect::<Vec<_>>();
-            let filter = move |entry: &DirEntry| {
-                if entry.file_type().is_file() {
-                    has_rs_extension(entry.path())
-                } else {
-                    nested.iter().all(|it| it != entry.path())
-                }
-            };
-            let task = io::Task {
-                root,
-                path: path.clone(),
-                filter: Box::new(filter),
-            };
-            res.worker.inp.send(task).unwrap();
-        }
-        let roots = res.roots.iter().map(|(id, _)| id).collect();
-        (res, roots)
+        let vfs_roots = res.roots.iter().map(|(id, _)| id).collect();
+        (res, vfs_roots)
     }
 
     pub fn root2path(&self, root: VfsRoot) -> PathBuf {
@@ -165,7 +218,7 @@ impl Vfs {
             } else {
                 let text = fs::read_to_string(path).unwrap_or_default();
                 let text = Arc::new(text);
-                let file = self.add_file(root, rel_path.clone(), Arc::clone(&text));
+                let file = self.add_file(root, rel_path.clone(), Arc::clone(&text), false);
                 let change = VfsChange::AddFile {
                     file,
                     text,
@@ -180,85 +233,130 @@ impl Vfs {
     }
 
     pub fn task_receiver(&self) -> &Receiver<io::TaskResult> {
-        &self.worker.out
+        self.worker.receiver()
     }
 
     pub fn handle_task(&mut self, task: io::TaskResult) {
-        let mut files = Vec::new();
-        // While we were scanning the root in the backgound, a file might have
-        // been open in the editor, so we need to account for that.
-        let exising = self.root2files[&task.root]
-            .iter()
-            .map(|&file| (self.files[file].path.clone(), file))
-            .collect::<FxHashMap<_, _>>();
-        for (path, text) in task.files {
-            if let Some(&file) = exising.get(&path) {
-                let text = Arc::clone(&self.files[file].text);
-                files.push((file, path, text));
-                continue;
+        match task {
+            TaskResult::BulkLoadRoot { root, files } => {
+                let mut cur_files = Vec::new();
+                // While we were scanning the root in the backgound, a file might have
+                // been open in the editor, so we need to account for that.
+                let exising = self.root2files[&root]
+                    .iter()
+                    .map(|&file| (self.files[file].path.clone(), file))
+                    .collect::<FxHashMap<_, _>>();
+                for (path, text) in files {
+                    if let Some(&file) = exising.get(&path) {
+                        let text = Arc::clone(&self.files[file].text);
+                        cur_files.push((file, path, text));
+                        continue;
+                    }
+                    let text = Arc::new(text);
+                    let file = self.add_file(root, path.clone(), Arc::clone(&text), false);
+                    cur_files.push((file, path, text));
+                }
+
+                let change = VfsChange::AddRoot {
+                    root,
+                    files: cur_files,
+                };
+                self.pending_changes.push(change);
+            }
+            TaskResult::AddSingleFile { root, path, text } => {
+                self.do_add_file(root, path, text, false);
+            }
+            TaskResult::ChangeSingleFile { root, path, text } => {
+                if let Some(file) = self.find_file(root, &path) {
+                    self.do_change_file(file, text, false);
+                } else {
+                    self.do_add_file(root, path, text, false);
+                }
+            }
+            TaskResult::RemoveSingleFile { root, path } => {
+                if let Some(file) = self.find_file(root, &path) {
+                    self.do_remove_file(root, path, file, false);
+                }
             }
-            let text = Arc::new(text);
-            let file = self.add_file(task.root, path.clone(), Arc::clone(&text));
-            files.push((file, path, text));
         }
+    }
 
-        let change = VfsChange::AddRoot {
-            root: task.root,
-            files,
-        };
-        self.pending_changes.push(change);
+    fn do_add_file(
+        &mut self,
+        root: VfsRoot,
+        path: RelativePathBuf,
+        text: String,
+        is_overlay: bool,
+    ) -> Option<VfsFile> {
+        let text = Arc::new(text);
+        let file = self.add_file(root, path.clone(), text.clone(), is_overlay);
+        self.pending_changes.push(VfsChange::AddFile {
+            file,
+            root,
+            path,
+            text,
+        });
+        Some(file)
+    }
+
+    fn do_change_file(&mut self, file: VfsFile, text: String, is_overlay: bool) {
+        if !is_overlay && self.files[file].is_overlayed {
+            return;
+        }
+        let text = Arc::new(text);
+        self.change_file(file, text.clone(), is_overlay);
+        self.pending_changes
+            .push(VfsChange::ChangeFile { file, text });
+    }
+
+    fn do_remove_file(
+        &mut self,
+        root: VfsRoot,
+        path: RelativePathBuf,
+        file: VfsFile,
+        is_overlay: bool,
+    ) {
+        if !is_overlay && self.files[file].is_overlayed {
+            return;
+        }
+        self.remove_file(file);
+        self.pending_changes
+            .push(VfsChange::RemoveFile { root, path, file });
     }
 
     pub fn add_file_overlay(&mut self, path: &Path, text: String) -> Option<VfsFile> {
-        let mut res = None;
-        if let Some((root, path, file)) = self.find_root(path) {
-            let text = Arc::new(text);
-            let change = if let Some(file) = file {
-                res = Some(file);
-                self.change_file(file, Arc::clone(&text));
-                VfsChange::ChangeFile { file, text }
+        if let Some((root, rel_path, file)) = self.find_root(path) {
+            if let Some(file) = file {
+                self.do_change_file(file, text, true);
+                Some(file)
             } else {
-                let file = self.add_file(root, path.clone(), Arc::clone(&text));
-                res = Some(file);
-                VfsChange::AddFile {
-                    file,
-                    text,
-                    root,
-                    path,
-                }
-            };
-            self.pending_changes.push(change);
+                self.do_add_file(root, rel_path, text, true)
+            }
+        } else {
+            None
         }
-        res
     }
 
     pub fn change_file_overlay(&mut self, path: &Path, new_text: String) {
         if let Some((_root, _path, file)) = self.find_root(path) {
             let file = file.expect("can't change a file which wasn't added");
-            let text = Arc::new(new_text);
-            self.change_file(file, Arc::clone(&text));
-            let change = VfsChange::ChangeFile { file, text };
-            self.pending_changes.push(change);
+            self.do_change_file(file, new_text, true);
         }
     }
 
     pub fn remove_file_overlay(&mut self, path: &Path) -> Option<VfsFile> {
-        let mut res = None;
         if let Some((root, path, file)) = self.find_root(path) {
             let file = file.expect("can't remove a file which wasn't added");
-            res = Some(file);
             let full_path = path.to_path(&self.roots[root].root);
-            let change = if let Ok(text) = fs::read_to_string(&full_path) {
-                let text = Arc::new(text);
-                self.change_file(file, Arc::clone(&text));
-                VfsChange::ChangeFile { file, text }
+            if let Ok(text) = fs::read_to_string(&full_path) {
+                self.do_change_file(file, text, true);
             } else {
-                self.remove_file(file);
-                VfsChange::RemoveFile { root, file, path }
-            };
-            self.pending_changes.push(change);
+                self.do_remove_file(root, path, file, true);
+            }
+            Some(file)
+        } else {
+            None
         }
-        res
     }
 
     pub fn commit_changes(&mut self) -> Vec<VfsChange> {
@@ -267,19 +365,31 @@ impl Vfs {
 
     /// Sutdown the VFS and terminate the background watching thread.
     pub fn shutdown(self) -> thread::Result<()> {
-        let _ = self.worker.shutdown();
-        self.worker_handle.shutdown()
+        self.worker.shutdown()
     }
 
-    fn add_file(&mut self, root: VfsRoot, path: RelativePathBuf, text: Arc<String>) -> VfsFile {
-        let data = VfsFileData { root, path, text };
+    fn add_file(
+        &mut self,
+        root: VfsRoot,
+        path: RelativePathBuf,
+        text: Arc<String>,
+        is_overlayed: bool,
+    ) -> VfsFile {
+        let data = VfsFileData {
+            root,
+            path,
+            text,
+            is_overlayed,
+        };
         let file = self.files.alloc(data);
         self.root2files.get_mut(&root).unwrap().insert(file);
         file
     }
 
-    fn change_file(&mut self, file: VfsFile, new_text: Arc<String>) {
-        self.files[file].text = new_text;
+    fn change_file(&mut self, file: VfsFile, new_text: Arc<String>, is_overlayed: bool) {
+        let mut file_data = &mut self.files[file];
+        file_data.text = new_text;
+        file_data.is_overlayed = is_overlayed;
     }
 
     fn remove_file(&mut self, file: VfsFile) {
@@ -292,15 +402,16 @@ impl Vfs {
     }
 
     fn find_root(&self, path: &Path) -> Option<(VfsRoot, RelativePathBuf, Option<VfsFile>)> {
-        let (root, path) = self
-            .roots
-            .iter()
-            .find_map(|(root, data)| data.can_contain(path).map(|it| (root, it)))?;
-        let file = self.root2files[&root]
+        let (root, path) = self.roots.find(&path)?;
+        let file = self.find_file(root, &path);
+        Some((root, path, file))
+    }
+
+    fn find_file(&self, root: VfsRoot, path: &RelativePath) -> Option<VfsFile> {
+        self.root2files[&root]
             .iter()
             .map(|&it| it)
-            .find(|&file| self.files[file].path == path);
-        Some((root, path, file))
+            .find(|&file| self.files[file].path == path)
     }
 }
 
diff --git a/crates/ra_vfs/tests/vfs.rs b/crates/ra_vfs/tests/vfs.rs
index f56fc4603..357e1c775 100644
--- a/crates/ra_vfs/tests/vfs.rs
+++ b/crates/ra_vfs/tests/vfs.rs
@@ -1,24 +1,47 @@
-use std::{
-    fs,
-    collections::HashSet,
-};
+use std::{collections::HashSet, fs, time::Duration};
 
+// use flexi_logger::Logger;
+use crossbeam_channel::RecvTimeoutError;
+use ra_vfs::{Vfs, VfsChange};
 use tempfile::tempdir;
 
-use ra_vfs::{Vfs, VfsChange};
+fn process_tasks(vfs: &mut Vfs, num_tasks: u32) {
+    for _ in 0..num_tasks {
+        let task = vfs
+            .task_receiver()
+            .recv_timeout(Duration::from_secs(3))
+            .unwrap();
+        log::debug!("{:?}", task);
+        vfs.handle_task(task);
+    }
+}
+
+macro_rules! assert_match {
+    ($x:expr, $pat:pat) => {
+        assert_match!($x, $pat, ())
+    };
+    ($x:expr, $pat:pat, $assert:expr) => {
+        match $x {
+            $pat => $assert,
+            x => assert!(false, "Expected {}, got {:?}", stringify!($pat), x),
+        };
+    };
+}
 
 #[test]
 fn test_vfs_works() -> std::io::Result<()> {
+    // Logger::with_str("vfs=debug,ra_vfs=debug").start().unwrap();
+
     let files = [
         ("a/foo.rs", "hello"),
         ("a/bar.rs", "world"),
         ("a/b/baz.rs", "nested hello"),
     ];
 
-    let dir = tempdir()?;
+    let dir = tempdir().unwrap();
     for (path, text) in files.iter() {
         let file_path = dir.path().join(path);
-        fs::create_dir_all(file_path.parent().unwrap())?;
+        fs::create_dir_all(file_path.parent().unwrap()).unwrap();
         fs::write(file_path, text)?
     }
 
@@ -26,10 +49,7 @@ fn test_vfs_works() -> std::io::Result<()> {
     let b_root = dir.path().join("a/b");
 
     let (mut vfs, _) = Vfs::new(vec![a_root, b_root]);
-    for _ in 0..2 {
-        let task = vfs.task_receiver().recv().unwrap();
-        vfs.handle_task(task);
-    }
+    process_tasks(&mut vfs, 2);
     {
         let files = vfs
             .commit_changes()
@@ -58,43 +78,101 @@ fn test_vfs_works() -> std::io::Result<()> {
         assert_eq!(files, expected_files);
     }
 
-    vfs.add_file_overlay(&dir.path().join("a/b/baz.rs"), "quux".to_string());
-    let change = vfs.commit_changes().pop().unwrap();
-    match change {
-        VfsChange::ChangeFile { text, .. } => assert_eq!(&*text, "quux"),
-        _ => panic!("unexpected change"),
-    }
+    fs::write(&dir.path().join("a/b/baz.rs"), "quux").unwrap();
+    process_tasks(&mut vfs, 1);
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::ChangeFile { text, .. }],
+        assert_eq!(text.as_str(), "quux")
+    );
 
-    vfs.change_file_overlay(&dir.path().join("a/b/baz.rs"), "m".to_string());
-    let change = vfs.commit_changes().pop().unwrap();
-    match change {
-        VfsChange::ChangeFile { text, .. } => assert_eq!(&*text, "m"),
-        _ => panic!("unexpected change"),
-    }
+    vfs.add_file_overlay(&dir.path().join("a/b/baz.rs"), "m".to_string());
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::ChangeFile { text, .. }],
+        assert_eq!(text.as_str(), "m")
+    );
 
+    // changing file on disk while overlayed doesn't generate a VfsChange
+    fs::write(&dir.path().join("a/b/baz.rs"), "corge").unwrap();
+    process_tasks(&mut vfs, 1);
+    assert_match!(vfs.commit_changes().as_slice(), []);
+
+    // removing overlay restores data on disk
     vfs.remove_file_overlay(&dir.path().join("a/b/baz.rs"));
-    let change = vfs.commit_changes().pop().unwrap();
-    match change {
-        VfsChange::ChangeFile { text, .. } => assert_eq!(&*text, "nested hello"),
-        _ => panic!("unexpected change"),
-    }
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::ChangeFile { text, .. }],
+        assert_eq!(text.as_str(), "corge")
+    );
 
     vfs.add_file_overlay(&dir.path().join("a/b/spam.rs"), "spam".to_string());
-    let change = vfs.commit_changes().pop().unwrap();
-    match change {
-        VfsChange::AddFile { text, path, .. } => {
-            assert_eq!(&*text, "spam");
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::AddFile { text, path, .. }],
+        {
+            assert_eq!(text.as_str(), "spam");
             assert_eq!(path, "spam.rs");
         }
-        _ => panic!("unexpected change"),
-    }
+    );
 
     vfs.remove_file_overlay(&dir.path().join("a/b/spam.rs"));
-    let change = vfs.commit_changes().pop().unwrap();
-    match change {
-        VfsChange::RemoveFile { .. } => (),
-        _ => panic!("unexpected change"),
-    }
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::RemoveFile { path, .. }],
+        assert_eq!(path, "spam.rs")
+    );
+
+    fs::create_dir_all(dir.path().join("a/sub1/sub2")).unwrap();
+    fs::write(dir.path().join("a/sub1/sub2/new.rs"), "new hello").unwrap();
+    process_tasks(&mut vfs, 1);
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::AddFile { text, path, .. }],
+        {
+            assert_eq!(text.as_str(), "new hello");
+            assert_eq!(path, "sub1/sub2/new.rs");
+        }
+    );
+
+    fs::rename(
+        &dir.path().join("a/sub1/sub2/new.rs"),
+        &dir.path().join("a/sub1/sub2/new1.rs"),
+    )
+    .unwrap();
+    process_tasks(&mut vfs, 2);
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::RemoveFile {
+            path: removed_path, ..
+        }, VfsChange::AddFile {
+            text,
+            path: added_path,
+            ..
+        }],
+        {
+            assert_eq!(removed_path, "sub1/sub2/new.rs");
+            assert_eq!(added_path, "sub1/sub2/new1.rs");
+            assert_eq!(text.as_str(), "new hello");
+        }
+    );
+
+    fs::remove_file(&dir.path().join("a/sub1/sub2/new1.rs")).unwrap();
+    process_tasks(&mut vfs, 1);
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::RemoveFile { path, .. }],
+        assert_eq!(path, "sub1/sub2/new1.rs")
+    );
+
+    // should be ignored
+    fs::create_dir_all(dir.path().join("a/target")).unwrap();
+    fs::write(&dir.path().join("a/target/new.rs"), "ignore me").unwrap();
+
+    assert_match!(
+        vfs.task_receiver().recv_timeout(Duration::from_millis(300)), // slightly more than watcher debounce delay
+        Err(RecvTimeoutError::Timeout)
+    );
 
     vfs.shutdown().unwrap();
     Ok(())