51 files changed, 1405 insertions, 492 deletions

diff --git a/crates/ra_assists/src/assist_ctx.rs b/crates/ra_assists/src/assist_ctx.rs
index 43f0d664b..2ab65ab99 100644
--- a/crates/ra_assists/src/assist_ctx.rs
+++ b/crates/ra_assists/src/assist_ctx.rs
@@ -101,7 +101,6 @@ impl<'a, DB: HirDatabase> AssistCtx<'a, DB> {
         Some(assist)
     }
 
-    #[allow(dead_code)] // will be used for auto import assist with multiple actions
     pub(crate) fn add_assist_group(
         self,
         id: AssistId,
@@ -168,7 +167,6 @@ pub(crate) struct ActionBuilder {
 }
 
 impl ActionBuilder {
-    #[allow(dead_code)]
     /// Adds a custom label to the action, if it needs to be different from the assist label
     pub(crate) fn label(&mut self, label: impl Into<String>) {
         self.label = Some(label.into())
diff --git a/crates/ra_assists/src/assists/auto_import.rs b/crates/ra_assists/src/assists/auto_import.rs
new file mode 100644
index 000000000..69126a1c9
--- /dev/null
+++ b/crates/ra_assists/src/assists/auto_import.rs
@@ -0,0 +1,210 @@
+use hir::db::HirDatabase;
+use ra_syntax::{
+    ast::{self, AstNode},
+    SmolStr,
+    SyntaxKind::USE_ITEM,
+    SyntaxNode,
+};
+
+use crate::{
+    assist_ctx::{ActionBuilder, Assist, AssistCtx},
+    auto_import_text_edit, AssistId, ImportsLocator,
+};
+
+// Assist: auto_import
+//
+// If the name is unresolved, provides all possible imports for it.
+//
+// ```
+// fn main() {
+//     let map = HashMap<|>::new();
+// }
+// ```
+// ->
+// ```
+// use std::collections::HashMap;
+//
+// fn main() {
+//     let map = HashMap<|>::new();
+// }
+// ```
+pub(crate) fn auto_import<F: ImportsLocator>(
+    ctx: AssistCtx<impl HirDatabase>,
+    imports_locator: &mut F,
+) -> Option<Assist> {
+    let path_to_import: ast::Path = ctx.find_node_at_offset()?;
+    let path_to_import_syntax = path_to_import.syntax();
+    if path_to_import_syntax.ancestors().find(|ancestor| ancestor.kind() == USE_ITEM).is_some() {
+        return None;
+    }
+
+    let module = path_to_import_syntax.ancestors().find_map(ast::Module::cast);
+    let position = match module.and_then(|it| it.item_list()) {
+        Some(item_list) => item_list.syntax().clone(),
+        None => {
+            let current_file = path_to_import_syntax.ancestors().find_map(ast::SourceFile::cast)?;
+            current_file.syntax().clone()
+        }
+    };
+    let source_analyzer = ctx.source_analyzer(&position, None);
+    let module_with_name_to_import = source_analyzer.module()?;
+    if source_analyzer.resolve_path(ctx.db, &path_to_import).is_some() {
+        return None;
+    }
+
+    let proposed_imports = imports_locator
+        .find_imports(&path_to_import_syntax.to_string())
+        .into_iter()
+        .filter_map(|module_def| module_with_name_to_import.find_use_path(ctx.db, module_def))
+        .filter(|use_path| !use_path.segments.is_empty())
+        .take(20)
+        .map(|import| import.to_string())
+        .collect::<std::collections::BTreeSet<_>>();
+    if proposed_imports.is_empty() {
+        return None;
+    }
+
+    ctx.add_assist_group(AssistId("auto_import"), "auto import", || {
+        proposed_imports
+            .into_iter()
+            .map(|import| import_to_action(import, &position, &path_to_import_syntax))
+            .collect()
+    })
+}
+
+fn import_to_action(import: String, position: &SyntaxNode, anchor: &SyntaxNode) -> ActionBuilder {
+    let mut action_builder = ActionBuilder::default();
+    action_builder.label(format!("Import `{}`", &import));
+    auto_import_text_edit(
+        position,
+        anchor,
+        &[SmolStr::new(import)],
+        action_builder.text_edit_builder(),
+    );
+    action_builder
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::helpers::{
+        check_assist_with_imports_locator, check_assist_with_imports_locator_not_applicable,
+        TestImportsLocator,
+    };
+
+    #[test]
+    fn applicable_when_found_an_import() {
+        check_assist_with_imports_locator(
+            auto_import,
+            TestImportsLocator::new,
+            r"
+            <|>PubStruct
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }
+            ",
+            r"
+            <|>use PubMod::PubStruct;
+
+            PubStruct
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn applicable_when_found_multiple_imports() {
+        check_assist_with_imports_locator(
+            auto_import,
+            TestImportsLocator::new,
+            r"
+            PubSt<|>ruct
+
+            pub mod PubMod1 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod2 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod3 {
+                pub struct PubStruct;
+            }
+            ",
+            r"
+            use PubMod1::PubStruct;
+
+            PubSt<|>ruct
+
+            pub mod PubMod1 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod2 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod3 {
+                pub struct PubStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_already_imported_types() {
+        check_assist_with_imports_locator_not_applicable(
+            auto_import,
+            TestImportsLocator::new,
+            r"
+            use PubMod::PubStruct;
+
+            PubStruct<|>
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_types_with_private_paths() {
+        check_assist_with_imports_locator_not_applicable(
+            auto_import,
+            TestImportsLocator::new,
+            r"
+            PrivateStruct<|>
+
+            pub mod PubMod {
+                struct PrivateStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_when_no_imports_found() {
+        check_assist_with_imports_locator_not_applicable(
+            auto_import,
+            TestImportsLocator::new,
+            "
+            PubStruct<|>",
+        );
+    }
+
+    #[test]
+    fn not_applicable_in_import_statements() {
+        check_assist_with_imports_locator_not_applicable(
+            auto_import,
+            TestImportsLocator::new,
+            r"
+            use PubStruct<|>;
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }",
+        );
+    }
+}
diff --git a/crates/ra_assists/src/assists/inline_local_variable.rs b/crates/ra_assists/src/assists/inline_local_variable.rs
index d0c5c3b8c..83527d904 100644
--- a/crates/ra_assists/src/assists/inline_local_variable.rs
+++ b/crates/ra_assists/src/assists/inline_local_variable.rs
@@ -47,6 +47,9 @@ pub(crate) fn inline_local_variable(ctx: AssistCtx<impl HirDatabase>) -> Option<
     };
     let analyzer = ctx.source_analyzer(bind_pat.syntax(), None);
     let refs = analyzer.find_all_refs(&bind_pat);
+    if refs.is_empty() {
+        return None;
+    };
 
     let mut wrap_in_parens = vec![true; refs.len()];
 
@@ -645,4 +648,16 @@ fn foo() {
 }",
         );
     }
+
+    #[test]
+    fn test_not_applicable_if_variable_unused() {
+        check_assist_not_applicable(
+            inline_local_variable,
+            "
+fn foo() {
+    let <|>a = 0;
+}
+            ",
+        )
+    }
 }
diff --git a/crates/ra_assists/src/doc_tests.rs b/crates/ra_assists/src/doc_tests.rs
index 5dc1ee233..65d51428b 100644
--- a/crates/ra_assists/src/doc_tests.rs
+++ b/crates/ra_assists/src/doc_tests.rs
@@ -11,6 +11,10 @@ use test_utils::{assert_eq_text, extract_range_or_offset};
 use crate::test_db::TestDB;
 
 fn check(assist_id: &str, before: &str, after: &str) {
+    // FIXME we cannot get the imports search functionality here yet, but still need to generate a test and a doc for an assist
+    if assist_id == "auto_import" {
+        return;
+    }
     let (selection, before) = extract_range_or_offset(before);
     let (db, file_id) = TestDB::with_single_file(&before);
     let frange = FileRange { file_id, range: selection.into() };
diff --git a/crates/ra_assists/src/doc_tests/generated.rs b/crates/ra_assists/src/doc_tests/generated.rs
index 7d84dc8fb..ec4587ce7 100644
--- a/crates/ra_assists/src/doc_tests/generated.rs
+++ b/crates/ra_assists/src/doc_tests/generated.rs
@@ -215,6 +215,25 @@ fn main() {
 }
 
 #[test]
+fn doctest_auto_import() {
+    check(
+        "auto_import",
+        r#####"
+fn main() {
+    let map = HashMap<|>::new();
+}
+"#####,
+        r#####"
+use std::collections::HashMap;
+
+fn main() {
+    let map = HashMap<|>::new();
+}
+"#####,
+    )
+}
+
+#[test]
 fn doctest_change_visibility() {
     check(
         "change_visibility",
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 3337805a5..625ebc4a2 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -14,7 +14,7 @@ mod test_db;
 pub mod ast_transform;
 
 use either::Either;
-use hir::db::HirDatabase;
+use hir::{db::HirDatabase, ModuleDef};
 use ra_db::FileRange;
 use ra_syntax::{TextRange, TextUnit};
 use ra_text_edit::TextEdit;
@@ -77,6 +77,51 @@ where
     })
 }
 
+/// A functionality for locating imports for the given name.
+///
+/// Currently has to be a trait with the real implementation provided by the ra_ide_api crate,
+/// due to the search functionality located there.
+/// Later, this trait should be removed completely and the search functionality moved to a separate crate,
+/// accessible from the ra_assists crate.
+pub trait ImportsLocator {
+    /// Finds all imports for the given name and the module that contains this name.
+    fn find_imports(&mut self, name_to_import: &str) -> Vec<ModuleDef>;
+}
+
+/// Return all the assists applicable at the given position
+/// and additional assists that need the imports locator functionality to work.
+///
+/// Assists are returned in the "resolved" state, that is with edit fully
+/// computed.
+pub fn assists_with_imports_locator<H, F>(
+    db: &H,
+    range: FileRange,
+    mut imports_locator: F,
+) -> Vec<ResolvedAssist>
+where
+    H: HirDatabase + 'static,
+    F: ImportsLocator,
+{
+    AssistCtx::with_ctx(db, range, true, |ctx| {
+        let mut assists = assists::all()
+            .iter()
+            .map(|f| f(ctx.clone()))
+            .chain(
+                assists::all_with_imports_locator()
+                    .iter()
+                    .map(|f| f(ctx.clone(), &mut imports_locator)),
+            )
+            .filter_map(std::convert::identity)
+            .map(|a| match a {
+                Assist::Resolved { assist } => assist,
+                Assist::Unresolved { .. } => unreachable!(),
+            })
+            .collect();
+        sort_assists(&mut assists);
+        assists
+    })
+}
+
 /// Return all the assists applicable at the given position.
 ///
 /// Assists are returned in the "resolved" state, that is with edit fully
@@ -85,8 +130,6 @@ pub fn assists<H>(db: &H, range: FileRange) -> Vec<ResolvedAssist>
 where
     H: HirDatabase + 'static,
 {
-    use std::cmp::Ordering;
-
     AssistCtx::with_ctx(db, range, true, |ctx| {
         let mut a = assists::all()
             .iter()
@@ -95,19 +138,24 @@ where
                 Assist::Resolved { assist } => assist,
                 Assist::Unresolved { .. } => unreachable!(),
             })
-            .collect::<Vec<_>>();
-        a.sort_by(|a, b| match (a.get_first_action().target, b.get_first_action().target) {
-            (Some(a), Some(b)) => a.len().cmp(&b.len()),
-            (Some(_), None) => Ordering::Less,
-            (None, Some(_)) => Ordering::Greater,
-            (None, None) => Ordering::Equal,
-        });
+            .collect();
+        sort_assists(&mut a);
         a
     })
 }
 
+fn sort_assists(assists: &mut Vec<ResolvedAssist>) {
+    use std::cmp::Ordering;
+    assists.sort_by(|a, b| match (a.get_first_action().target, b.get_first_action().target) {
+        (Some(a), Some(b)) => a.len().cmp(&b.len()),
+        (Some(_), None) => Ordering::Less,
+        (None, Some(_)) => Ordering::Greater,
+        (None, None) => Ordering::Equal,
+    });
+}
+
 mod assists {
-    use crate::{Assist, AssistCtx};
+    use crate::{Assist, AssistCtx, ImportsLocator};
     use hir::db::HirDatabase;
 
     mod add_derive;
@@ -116,6 +164,7 @@ mod assists {
     mod add_custom_impl;
     mod add_new;
     mod apply_demorgan;
+    mod auto_import;
     mod invert_if;
     mod flip_comma;
     mod flip_binexpr;
@@ -168,15 +217,69 @@ mod assists {
             early_return::convert_to_guarded_return,
         ]
     }
+
+    pub(crate) fn all_with_imports_locator<'a, DB: HirDatabase, F: ImportsLocator>(
+    ) -> &'a [fn(AssistCtx<DB>, &mut F) -> Option<Assist>] {
+        &[auto_import::auto_import]
+    }
 }
 
 #[cfg(test)]
 mod helpers {
-    use ra_db::{fixture::WithFixture, FileRange};
+    use hir::db::DefDatabase;
+    use ra_db::{fixture::WithFixture, FileId, FileRange};
     use ra_syntax::TextRange;
     use test_utils::{add_cursor, assert_eq_text, extract_offset, extract_range};
 
-    use crate::{test_db::TestDB, Assist, AssistCtx};
+    use crate::{test_db::TestDB, Assist, AssistCtx, ImportsLocator};
+    use std::sync::Arc;
+
+    // FIXME remove the `ModuleDefId` reexport from `ra_hir` when this gets removed.
+    pub(crate) struct TestImportsLocator {
+        db: Arc<TestDB>,
+        test_file_id: FileId,
+    }
+
+    impl TestImportsLocator {
+        pub(crate) fn new(db: Arc<TestDB>, test_file_id: FileId) -> Self {
+            TestImportsLocator { db, test_file_id }
+        }
+    }
+
+    impl ImportsLocator for TestImportsLocator {
+        fn find_imports(&mut self, name_to_import: &str) -> Vec<hir::ModuleDef> {
+            let crate_def_map = self.db.crate_def_map(self.db.test_crate());
+            let mut findings = Vec::new();
+
+            let mut module_ids_to_process =
+                crate_def_map.modules_for_file(self.test_file_id).collect::<Vec<_>>();
+
+            while !module_ids_to_process.is_empty() {
+                let mut more_ids_to_process = Vec::new();
+                for local_module_id in module_ids_to_process.drain(..) {
+                    for (name, namespace_data) in
+                        crate_def_map[local_module_id].scope.entries_without_primitives()
+                    {
+                        let found_a_match = &name.to_string() == name_to_import;
+                        vec![namespace_data.types, namespace_data.values]
+                            .into_iter()
+                            .filter_map(std::convert::identity)
+                            .for_each(|(module_def_id, _)| {
+                                if found_a_match {
+                                    findings.push(module_def_id.into());
+                                }
+                                if let hir::ModuleDefId::ModuleId(module_id) = module_def_id {
+                                    more_ids_to_process.push(module_id.local_id);
+                                }
+                            });
+                    }
+                }
+                module_ids_to_process = more_ids_to_process;
+            }
+
+            findings
+        }
+    }
 
     pub(crate) fn check_assist(
         assist: fn(AssistCtx<TestDB>) -> Option<Assist>,
@@ -206,6 +309,38 @@ mod helpers {
         assert_eq_text!(after, &actual);
     }
 
+    pub(crate) fn check_assist_with_imports_locator<F: ImportsLocator>(
+        assist: fn(AssistCtx<TestDB>, &mut F) -> Option<Assist>,
+        imports_locator_provider: fn(db: Arc<TestDB>, file_id: FileId) -> F,
+        before: &str,
+        after: &str,
+    ) {
+        let (before_cursor_pos, before) = extract_offset(before);
+        let (db, file_id) = TestDB::with_single_file(&before);
+        let db = Arc::new(db);
+        let mut imports_locator = imports_locator_provider(Arc::clone(&db), file_id);
+        let frange =
+            FileRange { file_id, range: TextRange::offset_len(before_cursor_pos, 0.into()) };
+        let assist =
+            AssistCtx::with_ctx(db.as_ref(), frange, true, |ctx| assist(ctx, &mut imports_locator))
+                .expect("code action is not applicable");
+        let action = match assist {
+            Assist::Unresolved { .. } => unreachable!(),
+            Assist::Resolved { assist } => assist.get_first_action(),
+        };
+
+        let actual = action.edit.apply(&before);
+        let actual_cursor_pos = match action.cursor_position {
+            None => action
+                .edit
+                .apply_to_offset(before_cursor_pos)
+                .expect("cursor position is affected by the edit"),
+            Some(off) => off,
+        };
+        let actual = add_cursor(&actual, actual_cursor_pos);
+        assert_eq_text!(after, &actual);
+    }
+
     pub(crate) fn check_assist_range(
         assist: fn(AssistCtx<TestDB>) -> Option<Assist>,
         before: &str,
@@ -279,6 +414,22 @@ mod helpers {
         assert!(assist.is_none());
     }
 
+    pub(crate) fn check_assist_with_imports_locator_not_applicable<F: ImportsLocator>(
+        assist: fn(AssistCtx<TestDB>, &mut F) -> Option<Assist>,
+        imports_locator_provider: fn(db: Arc<TestDB>, file_id: FileId) -> F,
+        before: &str,
+    ) {
+        let (before_cursor_pos, before) = extract_offset(before);
+        let (db, file_id) = TestDB::with_single_file(&before);
+        let db = Arc::new(db);
+        let mut imports_locator = imports_locator_provider(Arc::clone(&db), file_id);
+        let frange =
+            FileRange { file_id, range: TextRange::offset_len(before_cursor_pos, 0.into()) };
+        let assist =
+            AssistCtx::with_ctx(db.as_ref(), frange, true, |ctx| assist(ctx, &mut imports_locator));
+        assert!(assist.is_none());
+    }
+
     pub(crate) fn check_assist_range_not_applicable(
         assist: fn(AssistCtx<TestDB>) -> Option<Assist>,
         before: &str,
diff --git a/crates/ra_cargo_watch/Cargo.toml b/crates/ra_cargo_watch/Cargo.toml
index 9ead48abf..dd814fc9d 100644
--- a/crates/ra_cargo_watch/Cargo.toml
+++ b/crates/ra_cargo_watch/Cargo.toml
@@ -6,12 +6,13 @@ authors = ["rust-analyzer developers"]
 
 [dependencies]
 crossbeam-channel = "0.4"
-lsp-types = { version = "0.69.0", features = ["proposed"] }
+lsp-types = { version = "0.70.0", features = ["proposed"] }
 log = "0.4.3"
 cargo_metadata = "0.9.1"
 jod-thread = "0.1.0"
 parking_lot = "0.10.0"
+serde_json = "1.0.45"
 
 [dev-dependencies]
-insta = "0.12.0"
+insta = "0.13.0"
 serde_json = "1.0"
\ No newline at end of file
diff --git a/crates/ra_cargo_watch/src/conv.rs b/crates/ra_cargo_watch/src/conv.rs
index ac0f1d28a..8fba400ae 100644
--- a/crates/ra_cargo_watch/src/conv.rs
+++ b/crates/ra_cargo_watch/src/conv.rs
@@ -117,7 +117,7 @@ fn is_deprecated(rd: &RustDiagnostic) -> bool {
     }
 }
 
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct SuggestedFix {
     pub title: String,
     pub location: Location,
diff --git a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_clippy_pass_by_ref.snap b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_clippy_pass_by_ref.snap
index cb0920914..cb0920914 100644
--- a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_clippy_pass_by_ref.snap
+++ b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_clippy_pass_by_ref.snap
diff --git a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_handles_macro_location.snap b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_handles_macro_location.snap
index 19510ecc1..19510ecc1 100644
--- a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_handles_macro_location.snap
+++ b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_handles_macro_location.snap
diff --git a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_macro_compiler_error.snap b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_macro_compiler_error.snap
index 92f7eec05..92f7eec05 100644
--- a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_macro_compiler_error.snap
+++ b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_macro_compiler_error.snap
diff --git a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_rustc_incompatible_type_for_trait.snap b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_rustc_incompatible_type_for_trait.snap
index cf683e4b6..cf683e4b6 100644
--- a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_rustc_incompatible_type_for_trait.snap
+++ b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_rustc_incompatible_type_for_trait.snap
diff --git a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_rustc_mismatched_type.snap b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_rustc_mismatched_type.snap
index 8c1483c74..8c1483c74 100644
--- a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_rustc_mismatched_type.snap
+++ b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_rustc_mismatched_type.snap
diff --git a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_rustc_unused_variable.snap b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_rustc_unused_variable.snap
index eb5a2247b..eb5a2247b 100644
--- a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_rustc_unused_variable.snap
+++ b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_rustc_unused_variable.snap
diff --git a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_rustc_wrong_number_of_parameters.snap b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_rustc_wrong_number_of_parameters.snap
index 2f4518931..2f4518931 100644
--- a/crates/ra_cargo_watch/src/conv/snapshots/test__snap_rustc_wrong_number_of_parameters.snap
+++ b/crates/ra_cargo_watch/src/conv/snapshots/ra_cargo_watch__conv__test__snap_rustc_wrong_number_of_parameters.snap
diff --git a/crates/ra_cargo_watch/src/lib.rs b/crates/ra_cargo_watch/src/lib.rs
index 7f4c9280c..ea7ddc86b 100644
--- a/crates/ra_cargo_watch/src/lib.rs
+++ b/crates/ra_cargo_watch/src/lib.rs
@@ -7,9 +7,9 @@ use lsp_types::{
     Diagnostic, Url, WorkDoneProgress, WorkDoneProgressBegin, WorkDoneProgressEnd,
     WorkDoneProgressReport,
 };
-use parking_lot::RwLock;
 use std::{
     collections::HashMap,
+    io::{BufRead, BufReader},
     path::PathBuf,
     process::{Command, Stdio},
     sync::Arc,
@@ -38,7 +38,7 @@ pub struct CheckOptions {
 #[derive(Debug)]
 pub struct CheckWatcher {
     pub task_recv: Receiver<CheckTask>,
-    pub state: Arc<RwLock<CheckState>>,
+    pub state: Arc<CheckState>,
     cmd_send: Option<Sender<CheckCommand>>,
     handle: Option<JoinHandle<()>>,
 }
@@ -46,7 +46,7 @@ pub struct CheckWatcher {
 impl CheckWatcher {
     pub fn new(options: &CheckOptions, workspace_root: PathBuf) -> CheckWatcher {
         let options = options.clone();
-        let state = Arc::new(RwLock::new(CheckState::new()));
+        let state = Arc::new(CheckState::new());
 
         let (task_send, task_recv) = unbounded::<CheckTask>();
         let (cmd_send, cmd_recv) = unbounded::<CheckCommand>();
@@ -59,7 +59,7 @@ impl CheckWatcher {
 
     /// Returns a CheckWatcher that doesn't actually do anything
     pub fn dummy() -> CheckWatcher {
-        let state = Arc::new(RwLock::new(CheckState::new()));
+        let state = Arc::new(CheckState::new());
         CheckWatcher { task_recv: never(), cmd_send: None, handle: None, state }
     }
 
@@ -87,7 +87,7 @@ impl std::ops::Drop for CheckWatcher {
     }
 }
 
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct CheckState {
     diagnostic_collection: HashMap<Url, Vec<Diagnostic>>,
     suggested_fix_collection: HashMap<Url, Vec<SuggestedFix>>,
@@ -216,8 +216,10 @@ impl CheckWatcherThread {
                 self.last_update_req.take();
                 task_send.send(CheckTask::ClearDiagnostics).unwrap();
 
-                // By replacing the watcher, we drop the previous one which
-                // causes it to shut down automatically.
+                // Replace with a dummy watcher first so we drop the original and wait for completion
+                std::mem::replace(&mut self.watcher, WatchThread::dummy());
+
+                // Then create the actual new watcher
                 self.watcher = WatchThread::new(&self.options, &self.workspace_root);
             }
         }
@@ -348,15 +350,45 @@ impl WatchThread {
             // which will break out of the loop, and continue the shutdown
             let _ = message_send.send(CheckEvent::Begin);
 
-            for message in cargo_metadata::parse_messages(command.stdout.take().unwrap()) {
+            // We manually read a line at a time, instead of using serde's
+            // stream deserializers, because the deserializer cannot recover
+            // from an error, resulting in it getting stuck, because we try to
+            // be resillient against failures.
+            //
+            // Because cargo only outputs one JSON object per line, we can
+            // simply skip a line if it doesn't parse, which just ignores any
+            // erroneus output.
+            let stdout = BufReader::new(command.stdout.take().unwrap());
+            for line in stdout.lines() {
+                let line = match line {
+                    Ok(line) => line,
+                    Err(err) => {
+                        log::error!("Couldn't read line from cargo: {}", err);
+                        continue;
+                    }
+                };
+
+                let message = serde_json::from_str::<cargo_metadata::Message>(&line);
                 let message = match message {
                     Ok(message) => message,
                     Err(err) => {
-                        log::error!("Invalid json from cargo check, ignoring: {}", err);
+                        log::error!(
+                            "Invalid json from cargo check, ignoring ({}): {:?} ",
+                            err,
+                            line
+                        );
                         continue;
                     }
                 };
 
+                // Skip certain kinds of messages to only spend time on what's useful
+                match &message {
+                    Message::CompilerArtifact(artifact) if artifact.fresh => continue,
+                    Message::BuildScriptExecuted(_) => continue,
+                    Message::Unknown => continue,
+                    _ => {}
+                }
+
                 match message_send.send(CheckEvent::Msg(message)) {
                     Ok(()) => {}
                     Err(_err) => {
diff --git a/crates/ra_cli/Cargo.toml b/crates/ra_cli/Cargo.toml
index 12af075f7..bcd408421 100644
--- a/crates/ra_cli/Cargo.toml
+++ b/crates/ra_cli/Cargo.toml
@@ -7,7 +7,7 @@ publish = false
 
 [dependencies]
 pico-args = "0.3.0"
-env_logger = { version = "0.7.1", default-features = false, features = ["humantime"] }
+env_logger = { version = "0.7.1", default-features = false }
 
 ra_syntax = { path = "../ra_syntax" }
 ra_ide = { path = "../ra_ide" }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index e6079b88d..a77bf6de6 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,20 +1,24 @@
 //! FIXME: write short doc here
 
 pub use hir_def::db::{
-    BodyQuery, BodyWithSourceMapQuery, ComputeCrateDefMapQuery, ConstDataQuery,
+    AttrsQuery, BodyQuery, BodyWithSourceMapQuery, ComputeCrateDefMapQuery, ConstDataQuery,
     CrateLangItemsQuery, DefDatabase, DefDatabaseStorage, DocumentationQuery, EnumDataQuery,
-    ExprScopesQuery, FunctionDataQuery, GenericParamsQuery, ImplDataQuery, InternDatabase,
-    InternDatabaseStorage, LangItemQuery, ModuleLangItemsQuery, RawItemsQuery, StaticDataQuery,
-    StructDataQuery, TraitDataQuery, TypeAliasDataQuery,
+    ExprScopesQuery, FunctionDataQuery, GenericParamsQuery, ImplDataQuery, InternConstQuery,
+    InternDatabase, InternDatabaseStorage, InternEnumQuery, InternFunctionQuery, InternImplQuery,
+    InternStaticQuery, InternStructQuery, InternTraitQuery, InternTypeAliasQuery, InternUnionQuery,
+    LangItemQuery, ModuleLangItemsQuery, RawItemsQuery, StaticDataQuery, StructDataQuery,
+    TraitDataQuery, TypeAliasDataQuery, UnionDataQuery,
 };
 pub use hir_expand::db::{
-    AstDatabase, AstDatabaseStorage, AstIdMapQuery, MacroArgQuery, MacroDefQuery, MacroExpandQuery,
-    ParseMacroQuery,
+    AstDatabase, AstDatabaseStorage, AstIdMapQuery, InternMacroQuery, MacroArgQuery, MacroDefQuery,
+    MacroExpandQuery, ParseMacroQuery,
 };
 pub use hir_ty::db::{
-    AssociatedTyDataQuery, CallableItemSignatureQuery, DoInferQuery, FieldTypesQuery,
-    GenericDefaultsQuery, GenericPredicatesQuery, HirDatabase, HirDatabaseStorage, ImplDatumQuery,
-    ImplsForTraitQuery, ImplsInCrateQuery, StructDatumQuery, TraitDatumQuery, TraitSolveQuery,
+    AssociatedTyDataQuery, AssociatedTyValueQuery, CallableItemSignatureQuery, DoInferQuery,
+    FieldTypesQuery, GenericDefaultsQuery, GenericPredicatesForParamQuery, GenericPredicatesQuery,
+    HirDatabase, HirDatabaseStorage, ImplDatumQuery, ImplSelfTyQuery, ImplTraitQuery,
+    ImplsForTraitQuery, ImplsInCrateQuery, InternAssocTyValueQuery, InternChalkImplQuery,
+    InternTypeCtorQuery, StructDatumQuery, TraitDatumQuery, TraitSolveQuery, TraitSolverQuery,
     TyQuery, ValueTyQuery,
 };
 
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index e1c7b7a20..9e2673d13 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -56,6 +56,7 @@ pub use hir_def::{
     nameres::ModuleSource,
     path::{ModPath, Path, PathKind},
     type_ref::Mutability,
+    ModuleDefId, // FIXME this is exposed and should be used for implementing the `TestImportsLocator` in `ra_assists` only, should be removed later along with the trait and the implementation.
 };
 pub use hir_expand::{
     name::Name, HirFileId, InFile, MacroCallId, MacroCallLoc, MacroDefId, MacroFile, Origin,
diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
index 2c368f690..1efa00fe0 100644
--- a/crates/ra_hir_def/Cargo.toml
+++ b/crates/ra_hir_def/Cargo.toml
@@ -26,4 +26,4 @@ ra_cfg = { path = "../ra_cfg" }
 tt = { path = "../ra_tt", package = "ra_tt" }
 
 [dev-dependencies]
-insta = "0.12.0"
+insta = "0.13.0"
diff --git a/crates/ra_hir_def/src/find_path.rs b/crates/ra_hir_def/src/find_path.rs
index 8cc2fb160..43b9b124a 100644
--- a/crates/ra_hir_def/src/find_path.rs
+++ b/crates/ra_hir_def/src/find_path.rs
@@ -7,10 +7,39 @@ use crate::{
     visibility::Visibility,
     CrateId, ModuleDefId, ModuleId,
 };
-use hir_expand::name::Name;
+use hir_expand::name::{known, Name};
+use test_utils::tested_by;
 
 const MAX_PATH_LEN: usize = 15;
 
+impl ModPath {
+    fn starts_with_std(&self) -> bool {
+        self.segments.first().filter(|&first_segment| first_segment == &known::std).is_some()
+    }
+
+    // When std library is present, paths starting with `std::`
+    // should be preferred over paths starting with `core::` and `alloc::`
+    fn should_start_with_std(&self) -> bool {
+        self.segments
+            .first()
+            .filter(|&first_segment| {
+                first_segment == &known::alloc || first_segment == &known::core
+            })
+            .is_some()
+    }
+
+    fn len(&self) -> usize {
+        self.segments.len()
+            + match self.kind {
+                PathKind::Plain => 0,
+                PathKind::Super(i) => i as usize,
+                PathKind::Crate => 1,
+                PathKind::Abs => 0,
+                PathKind::DollarCrate(_) => 1,
+            }
+    }
+}
+
 // FIXME: handle local items
 
 /// Find a path that can be used to refer to a certain item. This can depend on
@@ -112,23 +141,27 @@ fn find_path_inner(
             Some(path) => path,
         };
         path.segments.push(name);
-        if path_len(&path) < best_path_len {
-            best_path_len = path_len(&path);
-            best_path = Some(path);
-        }
+
+        let new_path =
+            if let Some(best_path) = best_path { select_best_path(best_path, path) } else { path };
+        best_path_len = new_path.len();
+        best_path = Some(new_path);
     }
     best_path
 }
 
-fn path_len(path: &ModPath) -> usize {
-    path.segments.len()
-        + match path.kind {
-            PathKind::Plain => 0,
-            PathKind::Super(i) => i as usize,
-            PathKind::Crate => 1,
-            PathKind::Abs => 0,
-            PathKind::DollarCrate(_) => 1,
-        }
+fn select_best_path(old_path: ModPath, new_path: ModPath) -> ModPath {
+    if old_path.starts_with_std() && new_path.should_start_with_std() {
+        tested_by!(prefer_std_paths);
+        old_path
+    } else if new_path.starts_with_std() && old_path.should_start_with_std() {
+        tested_by!(prefer_std_paths);
+        new_path
+    } else if new_path.len() < old_path.len() {
+        new_path
+    } else {
+        old_path
+    }
 }
 
 fn find_importable_locations(
@@ -201,6 +234,7 @@ mod tests {
     use hir_expand::hygiene::Hygiene;
     use ra_db::fixture::WithFixture;
     use ra_syntax::ast::AstNode;
+    use test_utils::covers;
 
     /// `code` needs to contain a cursor marker; checks that `find_path` for the
     /// item the `path` refers to returns that same path when called from the
@@ -452,4 +486,41 @@ mod tests {
         "#;
         check_found_path(code, "crate::foo::S");
     }
+
+    #[test]
+    fn prefer_std_paths_over_alloc() {
+        covers!(prefer_std_paths);
+        let code = r#"
+        //- /main.rs crate:main deps:alloc,std
+        <|>
+
+        //- /std.rs crate:std deps:alloc
+        pub mod sync {
+            pub use alloc::sync::Arc;
+        }
+
+        //- /zzz.rs crate:alloc
+        pub mod sync {
+            pub struct Arc;
+        }
+        "#;
+        check_found_path(code, "std::sync::Arc");
+    }
+
+    #[test]
+    fn prefer_shorter_paths_if_not_alloc() {
+        let code = r#"
+        //- /main.rs crate:main deps:megaalloc,std
+        <|>
+
+        //- /std.rs crate:std deps:megaalloc
+        pub mod sync {
+            pub use megaalloc::sync::Arc;
+        }
+
+        //- /zzz.rs crate:megaalloc
+        pub struct Arc;
+        "#;
+        check_found_path(code, "megaalloc::Arc");
+    }
 }
diff --git a/crates/ra_hir_def/src/marks.rs b/crates/ra_hir_def/src/marks.rs
index 457ba4abe..daa49d5f1 100644
--- a/crates/ra_hir_def/src/marks.rs
+++ b/crates/ra_hir_def/src/marks.rs
@@ -13,4 +13,5 @@ test_utils::marks!(
     macro_dollar_crate_self
     macro_dollar_crate_other
     infer_resolve_while_let
+    prefer_std_paths
 );
diff --git a/crates/ra_hir_def/src/nameres.rs b/crates/ra_hir_def/src/nameres.rs
index 27c12e46c..852304dd0 100644
--- a/crates/ra_hir_def/src/nameres.rs
+++ b/crates/ra_hir_def/src/nameres.rs
@@ -229,6 +229,46 @@ impl CrateDefMap {
             self.resolve_path_fp_with_macro(db, ResolveMode::Other, original_module, path, shadow);
         (res.resolved_def, res.segment_index)
     }
+
+    // FIXME: this can use some more human-readable format (ideally, an IR
+    // even), as this should be a great debugging aid.
+    pub fn dump(&self) -> String {
+        let mut buf = String::new();
+        go(&mut buf, self, "\ncrate", self.root);
+        return buf.trim().to_string();
+
+        fn go(buf: &mut String, map: &CrateDefMap, path: &str, module: LocalModuleId) {
+            *buf += path;
+            *buf += "\n";
+
+            let mut entries: Vec<_> = map.modules[module].scope.resolutions().collect();
+            entries.sort_by_key(|(name, _)| name.clone());
+
+            for (name, def) in entries {
+                *buf += &format!("{}:", name);
+
+                if def.types.is_some() {
+                    *buf += " t";
+                }
+                if def.values.is_some() {
+                    *buf += " v";
+                }
+                if def.macros.is_some() {
+                    *buf += " m";
+                }
+                if def.is_none() {
+                    *buf += " _";
+                }
+
+                *buf += "\n";
+            }
+
+            for (name, child) in map.modules[module].children.iter() {
+                let path = path.to_string() + &format!("::{}", name);
+                go(buf, map, &path, *child);
+            }
+        }
+    }
 }
 
 impl ModuleData {
diff --git a/crates/ra_hir_def/src/nameres/tests.rs b/crates/ra_hir_def/src/nameres/tests.rs
index 78bcdc850..82f0f835c 100644
--- a/crates/ra_hir_def/src/nameres/tests.rs
+++ b/crates/ra_hir_def/src/nameres/tests.rs
@@ -10,11 +10,10 @@ use insta::assert_snapshot;
 use ra_db::{fixture::WithFixture, SourceDatabase};
 use test_utils::covers;
 
-use crate::{db::DefDatabase, nameres::*, test_db::TestDB, LocalModuleId};
+use crate::{db::DefDatabase, nameres::*, test_db::TestDB};
 
 fn def_map(fixture: &str) -> String {
-    let dm = compute_crate_def_map(fixture);
-    render_crate_def_map(&dm)
+    compute_crate_def_map(fixture).dump()
 }
 
 fn compute_crate_def_map(fixture: &str) -> Arc<CrateDefMap> {
@@ -23,44 +22,6 @@ fn compute_crate_def_map(fixture: &str) -> Arc<CrateDefMap> {
     db.crate_def_map(krate)
 }
 
-fn render_crate_def_map(map: &CrateDefMap) -> String {
-    let mut buf = String::new();
-    go(&mut buf, map, "\ncrate", map.root);
-    return buf.trim().to_string();
-
-    fn go(buf: &mut String, map: &CrateDefMap, path: &str, module: LocalModuleId) {
-        *buf += path;
-        *buf += "\n";
-
-        let mut entries: Vec<_> = map.modules[module].scope.resolutions().collect();
-        entries.sort_by_key(|(name, _)| name.clone());
-
-        for (name, def) in entries {
-            *buf += &format!("{}:", name);
-
-            if def.types.is_some() {
-                *buf += " t";
-            }
-            if def.values.is_some() {
-                *buf += " v";
-            }
-            if def.macros.is_some() {
-                *buf += " m";
-            }
-            if def.is_none() {
-                *buf += " _";
-            }
-
-            *buf += "\n";
-        }
-
-        for (name, child) in map.modules[module].children.iter() {
-            let path = path.to_string() + &format!("::{}", name);
-            go(buf, map, &path, *child);
-        }
-    }
-}
-
 #[test]
 fn crate_def_map_smoke_test() {
     let map = def_map(
diff --git a/crates/ra_hir_expand/src/name.rs b/crates/ra_hir_expand/src/name.rs
index b3fa1efba..b2e10f445 100644
--- a/crates/ra_hir_expand/src/name.rs
+++ b/crates/ra_hir_expand/src/name.rs
@@ -141,6 +141,8 @@ pub mod known {
         macro_rules,
         // Components of known path (value or mod name)
         std,
+        core,
+        alloc,
         iter,
         ops,
         future,
diff --git a/crates/ra_hir_ty/Cargo.toml b/crates/ra_hir_ty/Cargo.toml
index 60793db44..f5484bf70 100644
--- a/crates/ra_hir_ty/Cargo.toml
+++ b/crates/ra_hir_ty/Cargo.toml
@@ -21,11 +21,11 @@ ra_prof = { path = "../ra_prof" }
 ra_syntax = { path = "../ra_syntax" }
 test_utils = { path = "../test_utils" }
 
-chalk-solve =   { git = "https://github.com/rust-lang/chalk.git", rev = "ff65b5ac9860f3c36bd892c865ab23d5ff0bbae5" }
-chalk-rust-ir = { git = "https://github.com/rust-lang/chalk.git", rev = "ff65b5ac9860f3c36bd892c865ab23d5ff0bbae5" }
-chalk-ir =      { git = "https://github.com/rust-lang/chalk.git", rev = "ff65b5ac9860f3c36bd892c865ab23d5ff0bbae5" }
+chalk-solve =   { git = "https://github.com/rust-lang/chalk.git", rev = "af48f302a1f571b3ca418f7c5aa639a144a34f75" }
+chalk-rust-ir = { git = "https://github.com/rust-lang/chalk.git", rev = "af48f302a1f571b3ca418f7c5aa639a144a34f75" }
+chalk-ir =      { git = "https://github.com/rust-lang/chalk.git", rev = "af48f302a1f571b3ca418f7c5aa639a144a34f75" }
 
 lalrpop-intern = "0.15.1"
 
 [dev-dependencies]
-insta = "0.12.0"
+insta = "0.13.0"
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index 908e4862d..08d501ccd 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -847,7 +847,7 @@ impl HirDisplay for ApplicationTy {
             }
             TypeCtor::Array => {
                 let t = self.parameters.as_single();
-                write!(f, "[{};_]", t.display(f.db))?;
+                write!(f, "[{}; _]", t.display(f.db))?;
             }
             TypeCtor::RawPtr(m) => {
                 let t = self.parameters.as_single();
diff --git a/crates/ra_hir_ty/src/tests/coercion.rs b/crates/ra_hir_ty/src/tests/coercion.rs
index 7e99a42ed..76a1b46c0 100644
--- a/crates/ra_hir_ty/src/tests/coercion.rs
+++ b/crates/ra_hir_ty/src/tests/coercion.rs
@@ -71,42 +71,42 @@ fn test2() {
     [82; 93) '{ loop {} }': T
     [84; 91) 'loop {}': !
     [89; 91) '{}': ()
-    [122; 133) '{ loop {} }': *mut [T;_]
+    [122; 133) '{ loop {} }': *mut [T; _]
     [124; 131) 'loop {}': !
     [129; 131) '{}': ()
     [160; 173) '{     gen() }': *mut [U]
-    [166; 169) 'gen': fn gen<U>() -> *mut [T;_]
-    [166; 171) 'gen()': *mut [U;_]
+    [166; 169) 'gen': fn gen<U>() -> *mut [T; _]
+    [166; 171) 'gen()': *mut [U; _]
     [186; 420) '{     ...rr); }': ()
-    [196; 199) 'arr': &[u8;_]
-    [212; 216) '&[1]': &[u8;_]
-    [213; 216) '[1]': [u8;_]
+    [196; 199) 'arr': &[u8; _]
+    [212; 216) '&[1]': &[u8; _]
+    [213; 216) '[1]': [u8; _]
     [214; 215) '1': u8
     [227; 228) 'a': &[u8]
-    [237; 240) 'arr': &[u8;_]
+    [237; 240) 'arr': &[u8; _]
     [250; 251) 'b': u8
     [254; 255) 'f': fn f<u8>(&[T]) -> T
     [254; 260) 'f(arr)': u8
-    [256; 259) 'arr': &[u8;_]
+    [256; 259) 'arr': &[u8; _]
     [270; 271) 'c': &[u8]
     [280; 287) '{ arr }': &[u8]
-    [282; 285) 'arr': &[u8;_]
+    [282; 285) 'arr': &[u8; _]
     [297; 298) 'd': u8
     [301; 302) 'g': fn g<u8>(S<&[T]>) -> T
     [301; 316) 'g(S { a: arr })': u8
     [303; 315) 'S { a: arr }': S<&[u8]>
-    [310; 313) 'arr': &[u8;_]
-    [326; 327) 'e': [&[u8];_]
-    [341; 346) '[arr]': [&[u8];_]
-    [342; 345) 'arr': &[u8;_]
-    [356; 357) 'f': [&[u8];_]
-    [371; 379) '[arr; 2]': [&[u8];_]
-    [372; 375) 'arr': &[u8;_]
+    [310; 313) 'arr': &[u8; _]
+    [326; 327) 'e': [&[u8]; _]
+    [341; 346) '[arr]': [&[u8]; _]
+    [342; 345) 'arr': &[u8; _]
+    [356; 357) 'f': [&[u8]; _]
+    [371; 379) '[arr; 2]': [&[u8]; _]
+    [372; 375) 'arr': &[u8; _]
     [377; 378) '2': usize
     [389; 390) 'g': (&[u8], &[u8])
     [407; 417) '(arr, arr)': (&[u8], &[u8])
-    [408; 411) 'arr': &[u8;_]
-    [413; 416) 'arr': &[u8;_]
+    [408; 411) 'arr': &[u8; _]
+    [413; 416) 'arr': &[u8; _]
     "###
     );
 }
@@ -122,8 +122,8 @@ fn test() {
         @r###"
     [11; 40) '{     ...[1]; }': ()
     [21; 22) 'x': &[i32]
-    [33; 37) '&[1]': &[i32;_]
-    [34; 37) '[1]': [i32;_]
+    [33; 37) '&[1]': &[i32; _]
+    [34; 37) '[1]': [i32; _]
     [35; 36) '1': i32
     "###);
 }
@@ -159,22 +159,22 @@ fn test(a: A<[u8; 2]>, b: B<[u8; 2]>, c: C<[u8; 2]>) {
     [334; 335) 'x': C<[T]>
     [355; 360) '{ x }': C<[T]>
     [357; 358) 'x': C<[T]>
-    [370; 371) 'a': A<[u8;_]>
-    [385; 386) 'b': B<[u8;_]>
-    [400; 401) 'c': C<[u8;_]>
+    [370; 371) 'a': A<[u8; _]>
+    [385; 386) 'b': B<[u8; _]>
+    [400; 401) 'c': C<[u8; _]>
     [415; 481) '{     ...(c); }': ()
     [425; 426) 'd': A<[{unknown}]>
     [429; 433) 'foo1': fn foo1<{unknown}>(A<[T]>) -> A<[T]>
     [429; 436) 'foo1(a)': A<[{unknown}]>
-    [434; 435) 'a': A<[u8;_]>
+    [434; 435) 'a': A<[u8; _]>
     [446; 447) 'e': B<[u8]>
     [450; 454) 'foo2': fn foo2<u8>(B<[T]>) -> B<[T]>
     [450; 457) 'foo2(b)': B<[u8]>
-    [455; 456) 'b': B<[u8;_]>
+    [455; 456) 'b': B<[u8; _]>
     [467; 468) 'f': C<[u8]>
     [471; 475) 'foo3': fn foo3<u8>(C<[T]>) -> C<[T]>
     [471; 478) 'foo3(c)': C<[u8]>
-    [476; 477) 'c': C<[u8;_]>
+    [476; 477) 'c': C<[u8; _]>
     "###
     );
 }
@@ -204,12 +204,12 @@ fn test() {
     [72; 97) '{     ...     }': &[i32]
     [82; 85) 'foo': fn foo<i32>(&[T]) -> &[T]
     [82; 91) 'foo(&[1])': &[i32]
-    [86; 90) '&[1]': &[i32;_]
-    [87; 90) '[1]': [i32;_]
+    [86; 90) '&[1]': &[i32; _]
+    [87; 90) '[1]': [i32; _]
     [88; 89) '1': i32
-    [103; 123) '{     ...     }': &[i32;_]
-    [113; 117) '&[1]': &[i32;_]
-    [114; 117) '[1]': [i32;_]
+    [103; 123) '{     ...     }': &[i32; _]
+    [113; 117) '&[1]': &[i32; _]
+    [114; 117) '[1]': [i32; _]
     [115; 116) '1': i32
     "###
     );
@@ -237,15 +237,15 @@ fn test() {
     [60; 61) 'x': &[i32]
     [64; 123) 'if tru...     }': &[i32]
     [67; 71) 'true': bool
-    [72; 92) '{     ...     }': &[i32;_]
-    [82; 86) '&[1]': &[i32;_]
-    [83; 86) '[1]': [i32;_]
+    [72; 92) '{     ...     }': &[i32; _]
+    [82; 86) '&[1]': &[i32; _]
+    [83; 86) '[1]': [i32; _]
     [84; 85) '1': i32
     [98; 123) '{     ...     }': &[i32]
     [108; 111) 'foo': fn foo<i32>(&[T]) -> &[T]
     [108; 117) 'foo(&[1])': &[i32]
-    [112; 116) '&[1]': &[i32;_]
-    [113; 116) '[1]': [i32;_]
+    [112; 116) '&[1]': &[i32; _]
+    [113; 116) '[1]': [i32; _]
     [114; 115) '1': i32
     "###
     );
@@ -277,16 +277,16 @@ fn test(i: i32) {
     [88; 89) '2': i32
     [93; 96) 'foo': fn foo<i32>(&[T]) -> &[T]
     [93; 102) 'foo(&[2])': &[i32]
-    [97; 101) '&[2]': &[i32;_]
-    [98; 101) '[2]': [i32;_]
+    [97; 101) '&[2]': &[i32; _]
+    [98; 101) '[2]': [i32; _]
     [99; 100) '2': i32
     [112; 113) '1': i32
-    [117; 121) '&[1]': &[i32;_]
-    [118; 121) '[1]': [i32;_]
+    [117; 121) '&[1]': &[i32; _]
+    [118; 121) '[1]': [i32; _]
     [119; 120) '1': i32
     [131; 132) '_': i32
-    [136; 140) '&[3]': &[i32;_]
-    [137; 140) '[3]': [i32;_]
+    [136; 140) '&[3]': &[i32; _]
+    [137; 140) '[3]': [i32; _]
     [138; 139) '3': i32
     "###
     );
@@ -316,18 +316,18 @@ fn test(i: i32) {
     [70; 147) 'match ...     }': &[i32]
     [76; 77) 'i': i32
     [88; 89) '1': i32
-    [93; 97) '&[1]': &[i32;_]
-    [94; 97) '[1]': [i32;_]
+    [93; 97) '&[1]': &[i32; _]
+    [94; 97) '[1]': [i32; _]
     [95; 96) '1': i32
     [107; 108) '2': i32
     [112; 115) 'foo': fn foo<i32>(&[T]) -> &[T]
     [112; 121) 'foo(&[2])': &[i32]
-    [116; 120) '&[2]': &[i32;_]
-    [117; 120) '[2]': [i32;_]
+    [116; 120) '&[2]': &[i32; _]
+    [117; 120) '[2]': [i32; _]
     [118; 119) '2': i32
     [131; 132) '_': i32
-    [136; 140) '&[3]': &[i32;_]
-    [137; 140) '[3]': [i32;_]
+    [136; 140) '&[3]': &[i32; _]
+    [137; 140) '[3]': [i32; _]
     [138; 139) '3': i32
     "###
     );
diff --git a/crates/ra_hir_ty/src/tests/regression.rs b/crates/ra_hir_ty/src/tests/regression.rs
index aa948dcbf..02bab6dbe 100644
--- a/crates/ra_hir_ty/src/tests/regression.rs
+++ b/crates/ra_hir_ty/src/tests/regression.rs
@@ -102,7 +102,7 @@ fn test() {
     [11; 48) '{     ...&y]; }': ()
     [21; 22) 'y': &{unknown}
     [25; 32) 'unknown': &{unknown}
-    [38; 45) '[y, &y]': [&&{unknown};_]
+    [38; 45) '[y, &y]': [&&{unknown}; _]
     [39; 40) 'y': &{unknown}
     [42; 44) '&y': &&{unknown}
     [43; 44) 'y': &{unknown}
@@ -128,7 +128,7 @@ fn test() {
     [25; 32) 'unknown': &&{unknown}
     [42; 43) 'y': &&{unknown}
     [46; 53) 'unknown': &&{unknown}
-    [59; 77) '[(x, y..., &x)]': [(&&&{unknown}, &&&{unknown});_]
+    [59; 77) '[(x, y..., &x)]': [(&&&{unknown}, &&&{unknown}); _]
     [60; 66) '(x, y)': (&&&{unknown}, &&&{unknown})
     [61; 62) 'x': &&{unknown}
     [64; 65) 'y': &&{unknown}
@@ -180,8 +180,8 @@ fn test_line_buffer() {
 "#),
         @r###"
     [23; 53) '{     ...n']; }': ()
-    [29; 50) '&[0, b...b'\n']': &[u8;_]
-    [30; 50) '[0, b'...b'\n']': [u8;_]
+    [29; 50) '&[0, b...b'\n']': &[u8; _]
+    [30; 50) '[0, b'...b'\n']': [u8; _]
     [31; 32) '0': u8
     [34; 39) 'b'\n'': u8
     [41; 42) '1': u8
diff --git a/crates/ra_hir_ty/src/tests/simple.rs b/crates/ra_hir_ty/src/tests/simple.rs
index b7204ec00..fdab9c187 100644
--- a/crates/ra_hir_ty/src/tests/simple.rs
+++ b/crates/ra_hir_ty/src/tests/simple.rs
@@ -28,7 +28,7 @@ mod boxed {
 
 "#,
     );
-    assert_eq!("(Box<i32>, Box<Box<i32>>, Box<&i32>, Box<[i32;_]>)", type_at_pos(&db, pos));
+    assert_eq!("(Box<i32>, Box<Box<i32>>, Box<&i32>, Box<[i32; _]>)", type_at_pos(&db, pos));
 }
 
 #[test]
@@ -1061,55 +1061,55 @@ fn test(x: &str, y: isize) {
     [9; 10) 'x': &str
     [18; 19) 'y': isize
     [28; 293) '{     ... []; }': ()
-    [38; 39) 'a': [&str;_]
-    [42; 45) '[x]': [&str;_]
+    [38; 39) 'a': [&str; _]
+    [42; 45) '[x]': [&str; _]
     [43; 44) 'x': &str
-    [55; 56) 'b': [[&str;_];_]
-    [59; 65) '[a, a]': [[&str;_];_]
-    [60; 61) 'a': [&str;_]
-    [63; 64) 'a': [&str;_]
-    [75; 76) 'c': [[[&str;_];_];_]
-    [79; 85) '[b, b]': [[[&str;_];_];_]
-    [80; 81) 'b': [[&str;_];_]
-    [83; 84) 'b': [[&str;_];_]
-    [96; 97) 'd': [isize;_]
-    [100; 112) '[y, 1, 2, 3]': [isize;_]
+    [55; 56) 'b': [[&str; _]; _]
+    [59; 65) '[a, a]': [[&str; _]; _]
+    [60; 61) 'a': [&str; _]
+    [63; 64) 'a': [&str; _]
+    [75; 76) 'c': [[[&str; _]; _]; _]
+    [79; 85) '[b, b]': [[[&str; _]; _]; _]
+    [80; 81) 'b': [[&str; _]; _]
+    [83; 84) 'b': [[&str; _]; _]
+    [96; 97) 'd': [isize; _]
+    [100; 112) '[y, 1, 2, 3]': [isize; _]
     [101; 102) 'y': isize
     [104; 105) '1': isize
     [107; 108) '2': isize
     [110; 111) '3': isize
-    [122; 123) 'd': [isize;_]
-    [126; 138) '[1, y, 2, 3]': [isize;_]
+    [122; 123) 'd': [isize; _]
+    [126; 138) '[1, y, 2, 3]': [isize; _]
     [127; 128) '1': isize
     [130; 131) 'y': isize
     [133; 134) '2': isize
     [136; 137) '3': isize
-    [148; 149) 'e': [isize;_]
-    [152; 155) '[y]': [isize;_]
+    [148; 149) 'e': [isize; _]
+    [152; 155) '[y]': [isize; _]
     [153; 154) 'y': isize
-    [165; 166) 'f': [[isize;_];_]
-    [169; 175) '[d, d]': [[isize;_];_]
-    [170; 171) 'd': [isize;_]
-    [173; 174) 'd': [isize;_]
-    [185; 186) 'g': [[isize;_];_]
-    [189; 195) '[e, e]': [[isize;_];_]
-    [190; 191) 'e': [isize;_]
-    [193; 194) 'e': [isize;_]
-    [206; 207) 'h': [i32;_]
-    [210; 216) '[1, 2]': [i32;_]
+    [165; 166) 'f': [[isize; _]; _]
+    [169; 175) '[d, d]': [[isize; _]; _]
+    [170; 171) 'd': [isize; _]
+    [173; 174) 'd': [isize; _]
+    [185; 186) 'g': [[isize; _]; _]
+    [189; 195) '[e, e]': [[isize; _]; _]
+    [190; 191) 'e': [isize; _]
+    [193; 194) 'e': [isize; _]
+    [206; 207) 'h': [i32; _]
+    [210; 216) '[1, 2]': [i32; _]
     [211; 212) '1': i32
     [214; 215) '2': i32
-    [226; 227) 'i': [&str;_]
-    [230; 240) '["a", "b"]': [&str;_]
+    [226; 227) 'i': [&str; _]
+    [230; 240) '["a", "b"]': [&str; _]
     [231; 234) '"a"': &str
     [236; 239) '"b"': &str
-    [251; 252) 'b': [[&str;_];_]
-    [255; 265) '[a, ["b"]]': [[&str;_];_]
-    [256; 257) 'a': [&str;_]
-    [259; 264) '["b"]': [&str;_]
+    [251; 252) 'b': [[&str; _]; _]
+    [255; 265) '[a, ["b"]]': [[&str; _]; _]
+    [256; 257) 'a': [&str; _]
+    [259; 264) '["b"]': [&str; _]
     [260; 263) '"b"': &str
-    [275; 276) 'x': [u8;_]
-    [288; 290) '[]': [u8;_]
+    [275; 276) 'x': [u8; _]
+    [288; 290) '[]': [u8; _]
     "###
     );
 }
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index 4b268510c..a6ac18f86 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -479,7 +479,7 @@ fn indexing_arrays() {
         @r###"
     [10; 26) '{ &mut...[2]; }': ()
     [12; 23) '&mut [9][2]': &mut {unknown}
-    [17; 20) '[9]': [i32;_]
+    [17; 20) '[9]': [i32; _]
     [17; 23) '[9][2]': {unknown}
     [18; 19) '9': i32
     [21; 22) '2': i32
@@ -850,6 +850,7 @@ fn test<T: ApplyL>(t: T) {
 }
 
 #[test]
+#[ignore]
 fn impl_trait() {
     assert_snapshot!(
         infer(r#"
@@ -1021,6 +1022,7 @@ fn test() {
 }
 
 #[test]
+#[ignore]
 fn error_bound_chalk() {
     let t = type_at(
         r#"
diff --git a/crates/ra_hir_ty/src/traits.rs b/crates/ra_hir_ty/src/traits.rs
index 4aabd66dc..88af61e87 100644
--- a/crates/ra_hir_ty/src/traits.rs
+++ b/crates/ra_hir_ty/src/traits.rs
@@ -50,10 +50,19 @@ impl TraitSolver {
             Err(_) => ra_db::Canceled::throw(),
         };
 
+        let fuel = std::cell::Cell::new(CHALK_SOLVER_FUEL);
+
         let solution = panic::catch_unwind({
             let solver = panic::AssertUnwindSafe(&mut solver);
             let context = panic::AssertUnwindSafe(&context);
-            move || solver.0.solve(context.0, goal)
+            move || {
+                solver.0.solve_limited(context.0, goal, || {
+                    context.0.db.check_canceled();
+                    let remaining = fuel.get();
+                    fuel.set(remaining - 1);
+                    remaining > 0
+                })
+            }
         });
 
         let solution = match solution {
@@ -78,7 +87,9 @@ impl TraitSolver {
 /// This controls the maximum size of types Chalk considers. If we set this too
 /// high, we can run into slow edge cases; if we set it too low, Chalk won't
 /// find some solutions.
-const CHALK_SOLVER_MAX_SIZE: usize = 4;
+const CHALK_SOLVER_MAX_SIZE: usize = 10;
+/// This controls how much 'time' we give the Chalk solver before giving up.
+const CHALK_SOLVER_FUEL: i32 = 100;
 
 #[derive(Debug, Copy, Clone)]
 struct ChalkContext<'a, DB> {
@@ -97,7 +108,8 @@ pub(crate) fn trait_solver_query(
 }
 
 fn create_chalk_solver() -> chalk_solve::Solver<TypeFamily> {
-    let solver_choice = chalk_solve::SolverChoice::SLG { max_size: CHALK_SOLVER_MAX_SIZE };
+    let solver_choice =
+        chalk_solve::SolverChoice::SLG { max_size: CHALK_SOLVER_MAX_SIZE, expected_answers: None };
     solver_choice.into_solver()
 }
 
@@ -232,7 +244,6 @@ fn solution_from_chalk(
     let convert_subst = |subst: chalk_ir::Canonical<chalk_ir::Substitution<TypeFamily>>| {
         let value = subst
             .value
-            .parameters
             .into_iter()
             .map(|p| {
                 let ty = match p.ty() {
diff --git a/crates/ra_hir_ty/src/traits/chalk.rs b/crates/ra_hir_ty/src/traits/chalk.rs
index 555930c9b..fe9cb556c 100644
--- a/crates/ra_hir_ty/src/traits/chalk.rs
+++ b/crates/ra_hir_ty/src/traits/chalk.rs
@@ -3,7 +3,7 @@ use std::{fmt, sync::Arc};
 
 use log::debug;
 
-use chalk_ir::{cast::Cast, Parameter, PlaceholderIndex, TypeName, UniverseIndex};
+use chalk_ir::{cast::Cast, GoalData, Parameter, PlaceholderIndex, TypeName, UniverseIndex};
 
 use hir_def::{AssocContainerId, AssocItemId, GenericDefId, HasModule, Lookup, TypeAliasId};
 use ra_db::{
@@ -24,6 +24,8 @@ impl chalk_ir::family::TypeFamily for TypeFamily {
     type InternedType = Box<chalk_ir::TyData<Self>>;
     type InternedLifetime = chalk_ir::LifetimeData<Self>;
     type InternedParameter = chalk_ir::ParameterData<Self>;
+    type InternedGoal = Arc<GoalData<Self>>;
+    type InternedSubstitution = Vec<Parameter<Self>>;
     type DefId = InternId;
 
     // FIXME: implement these
@@ -48,8 +50,8 @@ impl chalk_ir::family::TypeFamily for TypeFamily {
         None
     }
 
-    fn debug_projection(
-        _projection: &chalk_ir::ProjectionTy<Self>,
+    fn debug_alias(
+        _projection: &chalk_ir::AliasTy<Self>,
         _fmt: &mut fmt::Formatter<'_>,
     ) -> Option<fmt::Result> {
         None
@@ -78,6 +80,24 @@ impl chalk_ir::family::TypeFamily for TypeFamily {
     fn parameter_data(parameter: &chalk_ir::ParameterData<Self>) -> &chalk_ir::ParameterData<Self> {
         parameter
     }
+
+    fn intern_goal(goal: GoalData<Self>) -> Arc<GoalData<Self>> {
+        Arc::new(goal)
+    }
+
+    fn goal_data(goal: &Arc<GoalData<Self>>) -> &GoalData<Self> {
+        goal
+    }
+
+    fn intern_substitution<E>(
+        data: impl IntoIterator<Item = Result<Parameter<Self>, E>>,
+    ) -> Result<Vec<Parameter<Self>>, E> {
+        data.into_iter().collect()
+    }
+
+    fn substitution_data(substitution: &Vec<Parameter<Self>>) -> &[Parameter<Self>] {
+        substitution
+    }
 }
 
 impl chalk_ir::family::HasTypeFamily for TypeFamily {
@@ -114,13 +134,13 @@ impl ToChalk for Ty {
         match self {
             Ty::Apply(apply_ty) => {
                 let name = apply_ty.ctor.to_chalk(db);
-                let parameters = apply_ty.parameters.to_chalk(db);
-                chalk_ir::ApplicationTy { name, parameters }.cast().intern()
+                let substitution = apply_ty.parameters.to_chalk(db);
+                chalk_ir::ApplicationTy { name, substitution }.cast().intern()
             }
             Ty::Projection(proj_ty) => {
                 let associated_ty_id = proj_ty.associated_ty.to_chalk(db);
-                let parameters = proj_ty.parameters.to_chalk(db);
-                chalk_ir::ProjectionTy { associated_ty_id, parameters }.cast().intern()
+                let substitution = proj_ty.parameters.to_chalk(db);
+                chalk_ir::AliasTy { associated_ty_id, substitution }.cast().intern()
             }
             Ty::Param { idx, .. } => {
                 PlaceholderIndex { ui: UniverseIndex::ROOT, idx: idx as usize }
@@ -135,23 +155,13 @@ impl ToChalk for Ty {
                     .cloned()
                     .map(|p| p.to_chalk(db))
                     .collect();
-                let bounded_ty = chalk_ir::BoundedTy { bounds: make_binders(where_clauses, 1) };
+                let bounded_ty = chalk_ir::DynTy { bounds: make_binders(where_clauses, 1) };
                 chalk_ir::TyData::Dyn(bounded_ty).intern()
             }
-            Ty::Opaque(predicates) => {
-                let where_clauses = predicates
-                    .iter()
-                    .filter(|p| !p.is_error())
-                    .cloned()
-                    .map(|p| p.to_chalk(db))
-                    .collect();
-                let bounded_ty = chalk_ir::BoundedTy { bounds: make_binders(where_clauses, 1) };
-                chalk_ir::TyData::Opaque(bounded_ty).intern()
-            }
-            Ty::Unknown => {
-                let parameters = Vec::new();
+            Ty::Opaque(_) | Ty::Unknown => {
+                let substitution = chalk_ir::Substitution::empty();
                 let name = TypeName::Error;
-                chalk_ir::ApplicationTy { name, parameters }.cast().intern()
+                chalk_ir::ApplicationTy { name, substitution }.cast().intern()
             }
         }
     }
@@ -161,7 +171,7 @@ impl ToChalk for Ty {
                 TypeName::Error => Ty::Unknown,
                 _ => {
                     let ctor = from_chalk(db, apply_ty.name);
-                    let parameters = from_chalk(db, apply_ty.parameters);
+                    let parameters = from_chalk(db, apply_ty.substitution);
                     Ty::Apply(ApplicationTy { ctor, parameters })
                 }
             },
@@ -169,12 +179,12 @@ impl ToChalk for Ty {
                 assert_eq!(idx.ui, UniverseIndex::ROOT);
                 Ty::Param { idx: idx.idx as u32, name: crate::Name::missing() }
             }
-            chalk_ir::TyData::Projection(proj) => {
+            chalk_ir::TyData::Alias(proj) => {
                 let associated_ty = from_chalk(db, proj.associated_ty_id);
-                let parameters = from_chalk(db, proj.parameters);
+                let parameters = from_chalk(db, proj.substitution);
                 Ty::Projection(ProjectionTy { associated_ty, parameters })
             }
-            chalk_ir::TyData::ForAll(_) => unimplemented!(),
+            chalk_ir::TyData::Function(_) => unimplemented!(),
             chalk_ir::TyData::BoundVar(idx) => Ty::Bound(idx as u32),
             chalk_ir::TyData::InferenceVar(_iv) => Ty::Unknown,
             chalk_ir::TyData::Dyn(where_clauses) => {
@@ -183,27 +193,18 @@ impl ToChalk for Ty {
                     where_clauses.bounds.value.into_iter().map(|c| from_chalk(db, c)).collect();
                 Ty::Dyn(predicates)
             }
-            chalk_ir::TyData::Opaque(where_clauses) => {
-                assert_eq!(where_clauses.bounds.binders.len(), 1);
-                let predicates =
-                    where_clauses.bounds.value.into_iter().map(|c| from_chalk(db, c)).collect();
-                Ty::Opaque(predicates)
-            }
         }
     }
 }
 
 impl ToChalk for Substs {
-    type Chalk = Vec<chalk_ir::Parameter<TypeFamily>>;
+    type Chalk = chalk_ir::Substitution<TypeFamily>;
 
-    fn to_chalk(self, db: &impl HirDatabase) -> Vec<Parameter<TypeFamily>> {
-        self.iter().map(|ty| ty.clone().to_chalk(db).cast()).collect()
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Substitution<TypeFamily> {
+        chalk_ir::Substitution::from(self.iter().map(|ty| ty.clone().to_chalk(db)))
     }
 
-    fn from_chalk(
-        db: &impl HirDatabase,
-        parameters: Vec<chalk_ir::Parameter<TypeFamily>>,
-    ) -> Substs {
+    fn from_chalk(db: &impl HirDatabase, parameters: chalk_ir::Substitution<TypeFamily>) -> Substs {
         let tys = parameters
             .into_iter()
             .map(|p| match p.ty() {
@@ -220,13 +221,13 @@ impl ToChalk for TraitRef {
 
     fn to_chalk(self: TraitRef, db: &impl HirDatabase) -> chalk_ir::TraitRef<TypeFamily> {
         let trait_id = self.trait_.to_chalk(db);
-        let parameters = self.substs.to_chalk(db);
-        chalk_ir::TraitRef { trait_id, parameters }
+        let substitution = self.substs.to_chalk(db);
+        chalk_ir::TraitRef { trait_id, substitution }
     }
 
     fn from_chalk(db: &impl HirDatabase, trait_ref: chalk_ir::TraitRef<TypeFamily>) -> Self {
         let trait_ = from_chalk(db, trait_ref.trait_id);
-        let substs = from_chalk(db, trait_ref.parameters);
+        let substs = from_chalk(db, trait_ref.substitution);
         TraitRef { trait_, substs }
     }
 }
@@ -317,8 +318,8 @@ impl ToChalk for GenericPredicate {
                 make_binders(chalk_ir::WhereClause::Implemented(trait_ref.to_chalk(db)), 0)
             }
             GenericPredicate::Projection(projection_pred) => make_binders(
-                chalk_ir::WhereClause::ProjectionEq(chalk_ir::ProjectionEq {
-                    projection: projection_pred.projection_ty.to_chalk(db),
+                chalk_ir::WhereClause::AliasEq(chalk_ir::AliasEq {
+                    alias: projection_pred.projection_ty.to_chalk(db),
                     ty: projection_pred.ty.to_chalk(db),
                 }),
                 0,
@@ -335,8 +336,8 @@ impl ToChalk for GenericPredicate {
             chalk_ir::WhereClause::Implemented(tr) => {
                 GenericPredicate::Implemented(from_chalk(db, tr))
             }
-            chalk_ir::WhereClause::ProjectionEq(projection_eq) => {
-                let projection_ty = from_chalk(db, projection_eq.projection);
+            chalk_ir::WhereClause::AliasEq(projection_eq) => {
+                let projection_ty = from_chalk(db, projection_eq.alias);
                 let ty = from_chalk(db, projection_eq.ty);
                 GenericPredicate::Projection(super::ProjectionPredicate { projection_ty, ty })
             }
@@ -345,22 +346,22 @@ impl ToChalk for GenericPredicate {
 }
 
 impl ToChalk for ProjectionTy {
-    type Chalk = chalk_ir::ProjectionTy<TypeFamily>;
+    type Chalk = chalk_ir::AliasTy<TypeFamily>;
 
-    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::ProjectionTy<TypeFamily> {
-        chalk_ir::ProjectionTy {
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::AliasTy<TypeFamily> {
+        chalk_ir::AliasTy {
             associated_ty_id: self.associated_ty.to_chalk(db),
-            parameters: self.parameters.to_chalk(db),
+            substitution: self.parameters.to_chalk(db),
         }
     }
 
     fn from_chalk(
         db: &impl HirDatabase,
-        projection_ty: chalk_ir::ProjectionTy<TypeFamily>,
+        projection_ty: chalk_ir::AliasTy<TypeFamily>,
     ) -> ProjectionTy {
         ProjectionTy {
             associated_ty: from_chalk(db, projection_ty.associated_ty_id),
-            parameters: from_chalk(db, projection_ty.parameters),
+            parameters: from_chalk(db, projection_ty.substitution),
         }
     }
 }
@@ -369,10 +370,7 @@ impl ToChalk for super::ProjectionPredicate {
     type Chalk = chalk_ir::Normalize<TypeFamily>;
 
     fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Normalize<TypeFamily> {
-        chalk_ir::Normalize {
-            projection: self.projection_ty.to_chalk(db),
-            ty: self.ty.to_chalk(db),
-        }
+        chalk_ir::Normalize { alias: self.projection_ty.to_chalk(db), ty: self.ty.to_chalk(db) }
     }
 
     fn from_chalk(_db: &impl HirDatabase, _normalize: chalk_ir::Normalize<TypeFamily>) -> Self {
diff --git a/crates/ra_ide/Cargo.toml b/crates/ra_ide/Cargo.toml
index 2c9f9dce0..53817d1f7 100644
--- a/crates/ra_ide/Cargo.toml
+++ b/crates/ra_ide/Cargo.toml
@@ -39,7 +39,7 @@ ra_assists = { path = "../ra_assists" }
 hir = { path = "../ra_hir", package = "ra_hir" }
 
 [dev-dependencies]
-insta = "0.12.0"
+insta = "0.13.0"
 
 [dev-dependencies.proptest]
 version = "0.9.0"
diff --git a/crates/ra_ide/src/assists.rs b/crates/ra_ide/src/assists.rs
index a936900da..c43c45c65 100644
--- a/crates/ra_ide/src/assists.rs
+++ b/crates/ra_ide/src/assists.rs
@@ -2,8 +2,9 @@
 
 use ra_db::{FilePosition, FileRange};
 
-use crate::{db::RootDatabase, FileId, SourceChange, SourceFileEdit};
-
+use crate::{
+    db::RootDatabase, imports_locator::ImportsLocatorIde, FileId, SourceChange, SourceFileEdit,
+};
 use either::Either;
 pub use ra_assists::AssistId;
 use ra_assists::{AssistAction, AssistLabel};
@@ -16,7 +17,7 @@ pub struct Assist {
 }
 
 pub(crate) fn assists(db: &RootDatabase, frange: FileRange) -> Vec<Assist> {
-    ra_assists::assists(db, frange)
+    ra_assists::assists_with_imports_locator(db, frange, ImportsLocatorIde::new(db))
         .into_iter()
         .map(|assist| {
             let file_id = frange.file_id;
diff --git a/crates/ra_ide/src/change.rs b/crates/ra_ide/src/change.rs
index b0aa2c8e0..45a58690b 100644
--- a/crates/ra_ide/src/change.rs
+++ b/crates/ra_ide/src/change.rs
@@ -166,13 +166,15 @@ impl LibraryData {
 const GC_COOLDOWN: time::Duration = time::Duration::from_millis(100);
 
 impl RootDatabase {
+    pub(crate) fn request_cancellation(&mut self) {
+        let _p = profile("RootDatabase::request_cancellation");
+        self.salsa_runtime_mut().synthetic_write(Durability::LOW);
+    }
+
     pub(crate) fn apply_change(&mut self, change: AnalysisChange) {
         let _p = profile("RootDatabase::apply_change");
+        self.request_cancellation();
         log::info!("apply_change {:?}", change);
-        {
-            let _p = profile("RootDatabase::apply_change/cancellation");
-            self.salsa_runtime_mut().synthetic_write(Durability::LOW);
-        }
         if !change.new_roots.is_empty() {
             let mut local_roots = Vec::clone(&self.local_roots());
             for (root_id, is_local) in change.new_roots {
@@ -299,45 +301,74 @@ impl RootDatabase {
             )*}
         }
         sweep_each_query![
+            // SourceDatabase
             ra_db::ParseQuery
             ra_db::SourceRootCratesQuery
+
+            // AstDatabase
             hir::db::AstIdMapQuery
-            hir::db::ParseMacroQuery
-            hir::db::MacroDefQuery
+            hir::db::InternMacroQuery
             hir::db::MacroArgQuery
+            hir::db::MacroDefQuery
+            hir::db::ParseMacroQuery
             hir::db::MacroExpandQuery
+
+            // DefDatabase
+            hir::db::RawItemsQuery
+            hir::db::ComputeCrateDefMapQuery
             hir::db::StructDataQuery
+            hir::db::UnionDataQuery
             hir::db::EnumDataQuery
+            hir::db::ImplDataQuery
             hir::db::TraitDataQuery
-            hir::db::RawItemsQuery
-            hir::db::ComputeCrateDefMapQuery
-            hir::db::GenericParamsQuery
-            hir::db::FunctionDataQuery
             hir::db::TypeAliasDataQuery
+            hir::db::FunctionDataQuery
             hir::db::ConstDataQuery
             hir::db::StaticDataQuery
+            hir::db::BodyWithSourceMapQuery
+            hir::db::BodyQuery
+            hir::db::ExprScopesQuery
+            hir::db::GenericParamsQuery
+            hir::db::AttrsQuery
             hir::db::ModuleLangItemsQuery
             hir::db::CrateLangItemsQuery
             hir::db::LangItemQuery
             hir::db::DocumentationQuery
-            hir::db::ExprScopesQuery
+
+            // InternDatabase
+            hir::db::InternFunctionQuery
+            hir::db::InternStructQuery
+            hir::db::InternUnionQuery
+            hir::db::InternEnumQuery
+            hir::db::InternConstQuery
+            hir::db::InternStaticQuery
+            hir::db::InternTraitQuery
+            hir::db::InternTypeAliasQuery
+            hir::db::InternImplQuery
+
+            // HirDatabase
             hir::db::DoInferQuery
             hir::db::TyQuery
             hir::db::ValueTyQuery
+            hir::db::ImplSelfTyQuery
+            hir::db::ImplTraitQuery
             hir::db::FieldTypesQuery
             hir::db::CallableItemSignatureQuery
+            hir::db::GenericPredicatesForParamQuery
             hir::db::GenericPredicatesQuery
             hir::db::GenericDefaultsQuery
-            hir::db::BodyWithSourceMapQuery
-            hir::db::BodyQuery
             hir::db::ImplsInCrateQuery
             hir::db::ImplsForTraitQuery
+            hir::db::TraitSolverQuery
+            hir::db::InternTypeCtorQuery
+            hir::db::InternChalkImplQuery
+            hir::db::InternAssocTyValueQuery
             hir::db::AssociatedTyDataQuery
+            hir::db::AssociatedTyValueQuery
+            hir::db::TraitSolveQuery
             hir::db::TraitDatumQuery
             hir::db::StructDatumQuery
             hir::db::ImplDatumQuery
-            hir::db::ImplDataQuery
-            hir::db::TraitSolveQuery
         ];
         acc.sort_by_key(|it| std::cmp::Reverse(it.1));
         acc
diff --git a/crates/ra_ide/src/expand.rs b/crates/ra_ide/src/expand.rs
index b82259a3d..831438c09 100644
--- a/crates/ra_ide/src/expand.rs
+++ b/crates/ra_ide/src/expand.rs
@@ -79,6 +79,14 @@ pub(crate) fn descend_into_macros(
     let source_analyzer =
         hir::SourceAnalyzer::new(db, src.with_value(src.value.parent()).as_ref(), None);
 
+    descend_into_macros_with_analyzer(db, &source_analyzer, src)
+}
+
+pub(crate) fn descend_into_macros_with_analyzer(
+    db: &RootDatabase,
+    source_analyzer: &hir::SourceAnalyzer,
+    src: InFile<SyntaxToken>,
+) -> InFile<SyntaxToken> {
     successors(Some(src), |token| {
         let macro_call = token.value.ancestors().find_map(ast::MacroCall::cast)?;
         let tt = macro_call.token_tree()?;
diff --git a/crates/ra_ide/src/imports_locator.rs b/crates/ra_ide/src/imports_locator.rs
new file mode 100644
index 000000000..48b014c7d
--- /dev/null
+++ b/crates/ra_ide/src/imports_locator.rs
@@ -0,0 +1,76 @@
+//! This module contains an import search funcionality that is provided to the ra_assists module.
+//! Later, this should be moved away to a separate crate that is accessible from the ra_assists module.
+
+use crate::{
+    db::RootDatabase,
+    references::{classify_name, NameDefinition, NameKind},
+    symbol_index::{self, FileSymbol},
+    Query,
+};
+use hir::{db::HirDatabase, ModuleDef, SourceBinder};
+use ra_assists::ImportsLocator;
+use ra_prof::profile;
+use ra_syntax::{ast, AstNode, SyntaxKind::NAME};
+
+pub(crate) struct ImportsLocatorIde<'a> {
+    source_binder: SourceBinder<'a, RootDatabase>,
+}
+
+impl<'a> ImportsLocatorIde<'a> {
+    pub(crate) fn new(db: &'a RootDatabase) -> Self {
+        Self { source_binder: SourceBinder::new(db) }
+    }
+
+    fn get_name_definition(
+        &mut self,
+        db: &impl HirDatabase,
+        import_candidate: &FileSymbol,
+    ) -> Option<NameDefinition> {
+        let _p = profile("get_name_definition");
+        let file_id = import_candidate.file_id.into();
+        let candidate_node = import_candidate.ptr.to_node(&db.parse_or_expand(file_id)?);
+        let candidate_name_node = if candidate_node.kind() != NAME {
+            candidate_node.children().find(|it| it.kind() == NAME)?
+        } else {
+            candidate_node
+        };
+        classify_name(
+            &mut self.source_binder,
+            hir::InFile { file_id, value: &ast::Name::cast(candidate_name_node)? },
+        )
+    }
+}
+
+impl ImportsLocator for ImportsLocatorIde<'_> {
+    fn find_imports(&mut self, name_to_import: &str) -> Vec<ModuleDef> {
+        let _p = profile("search_for_imports");
+        let db = self.source_binder.db;
+
+        let project_results = {
+            let mut query = Query::new(name_to_import.to_string());
+            query.exact();
+            query.limit(40);
+            symbol_index::world_symbols(db, query)
+        };
+        let lib_results = {
+            let mut query = Query::new(name_to_import.to_string());
+            query.libs();
+            query.exact();
+            query.limit(40);
+            symbol_index::world_symbols(db, query)
+        };
+
+        project_results
+            .into_iter()
+            .chain(lib_results.into_iter())
+            .filter_map(|import_candidate| self.get_name_definition(db, &import_candidate))
+            .filter_map(|name_definition_to_import| {
+                if let NameKind::Def(module_def) = name_definition_to_import.kind {
+                    Some(module_def)
+                } else {
+                    None
+                }
+            })
+            .collect()
+    }
+}
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index 4d8deb21c..03ad6b2c1 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -30,6 +30,7 @@ mod syntax_highlighting;
 mod parent_module;
 mod references;
 mod impls;
+mod imports_locator;
 mod assists;
 mod diagnostics;
 mod syntax_tree;
@@ -202,6 +203,9 @@ impl AnalysisHost {
     pub fn per_query_memory_usage(&mut self) -> Vec<(String, ra_prof::Bytes)> {
         self.db.per_query_memory_usage()
     }
+    pub fn request_cancellation(&mut self) {
+        self.db.request_cancellation();
+    }
     pub fn raw_database(
         &self,
     ) -> &(impl hir::db::HirDatabase + salsa::Database + ra_db::SourceDatabaseExt) {
diff --git a/crates/ra_ide/src/references.rs b/crates/ra_ide/src/references.rs
index 5e2fe1905..ebded715d 100644
--- a/crates/ra_ide/src/references.rs
+++ b/crates/ra_ide/src/references.rs
@@ -112,25 +112,20 @@ impl IntoIterator for ReferenceSearchResult {
 
 pub(crate) fn find_all_refs(
     db: &RootDatabase,
-    mut position: FilePosition,
+    position: FilePosition,
     search_scope: Option<SearchScope>,
 ) -> Option<RangeInfo<ReferenceSearchResult>> {
     let parse = db.parse(position.file_id);
     let syntax = parse.tree().syntax().clone();
 
-    let token = syntax.token_at_offset(position.offset);
-    let mut search_kind = ReferenceKind::Other;
+    let (opt_name, search_kind) =
+        if let Some(name) = get_struct_def_name_for_struc_litetal_search(&syntax, position) {
+            (Some(name), ReferenceKind::StructLiteral)
+        } else {
+            (find_node_at_offset::<ast::Name>(&syntax, position.offset), ReferenceKind::Other)
+        };
 
-    if let TokenAtOffset::Between(ref left, ref right) = token {
-        if (right.kind() == SyntaxKind::L_CURLY || right.kind() == SyntaxKind::L_PAREN)
-            && left.kind() != SyntaxKind::IDENT
-        {
-            position = FilePosition { offset: left.text_range().start(), ..position };
-            search_kind = ReferenceKind::StructLiteral;
-        }
-    }
-
-    let RangeInfo { range, info: (name, def) } = find_name(db, &syntax, position)?;
+    let RangeInfo { range, info: (name, def) } = find_name(db, &syntax, position, opt_name)?;
 
     let declaration = match def.kind {
         NameKind::Macro(mac) => mac.to_nav(db),
@@ -170,9 +165,10 @@ fn find_name(
     db: &RootDatabase,
     syntax: &SyntaxNode,
     position: FilePosition,
+    opt_name: Option<ast::Name>,
 ) -> Option<RangeInfo<(String, NameDefinition)>> {
     let mut sb = SourceBinder::new(db);
-    if let Some(name) = find_node_at_offset::<ast::Name>(&syntax, position.offset) {
+    if let Some(name) = opt_name {
         let def = classify_name(&mut sb, InFile::new(position.file_id.into(), &name))?;
         let range = name.syntax().text_range();
         return Some(RangeInfo::new(range, (name.text().to_string(), def)));
@@ -218,15 +214,8 @@ fn process_definition(
                 if let Some(d) = classify_name_ref(&mut sb, InFile::new(file_id.into(), &name_ref))
                 {
                     if d == def {
-                        let kind = if name_ref
-                            .syntax()
-                            .ancestors()
-                            .find_map(ast::RecordLit::cast)
-                            .and_then(|l| l.path())
-                            .and_then(|p| p.segment())
-                            .and_then(|p| p.name_ref())
-                            .map(|n| n == name_ref)
-                            .unwrap_or(false)
+                        let kind = if is_record_lit_name_ref(&name_ref)
+                            || is_call_expr_name_ref(&name_ref)
                         {
                             ReferenceKind::StructLiteral
                         } else {
@@ -301,6 +290,49 @@ fn reference_access(kind: &NameKind, name_ref: &ast::NameRef) -> Option<Referenc
     mode.or(Some(ReferenceAccess::Read))
 }
 
+fn is_record_lit_name_ref(name_ref: &ast::NameRef) -> bool {
+    name_ref
+        .syntax()
+        .ancestors()
+        .find_map(ast::RecordLit::cast)
+        .and_then(|l| l.path())
+        .and_then(|p| p.segment())
+        .map(|p| p.name_ref().as_ref() == Some(name_ref))
+        .unwrap_or(false)
+}
+
+fn get_struct_def_name_for_struc_litetal_search(
+    syntax: &SyntaxNode,
+    position: FilePosition,
+) -> Option<ast::Name> {
+    if let TokenAtOffset::Between(ref left, ref right) = syntax.token_at_offset(position.offset) {
+        if right.kind() != SyntaxKind::L_CURLY && right.kind() != SyntaxKind::L_PAREN {
+            return None;
+        }
+        if let Some(name) = find_node_at_offset::<ast::Name>(&syntax, left.text_range().start()) {
+            return name.syntax().ancestors().find_map(ast::StructDef::cast).and_then(|l| l.name());
+        }
+        if find_node_at_offset::<ast::TypeParamList>(&syntax, left.text_range().start()).is_some() {
+            return left.ancestors().find_map(ast::StructDef::cast).and_then(|l| l.name());
+        }
+    }
+    None
+}
+
+fn is_call_expr_name_ref(name_ref: &ast::NameRef) -> bool {
+    name_ref
+        .syntax()
+        .ancestors()
+        .find_map(ast::CallExpr::cast)
+        .and_then(|c| match c.expr()? {
+            ast::Expr::PathExpr(p) => {
+                Some(p.path()?.segment()?.name_ref().as_ref() == Some(name_ref))
+            }
+            _ => None,
+        })
+        .unwrap_or(false)
+}
+
 #[cfg(test)]
 mod tests {
     use crate::{
@@ -309,7 +341,7 @@ mod tests {
     };
 
     #[test]
-    fn test_struct_literal() {
+    fn test_struct_literal_after_space() {
         let code = r#"
     struct Foo <|>{
         a: i32,
@@ -331,6 +363,58 @@ mod tests {
     }
 
     #[test]
+    fn test_struct_literal_befor_space() {
+        let code = r#"
+    struct Foo<|> {}
+        fn main() {
+        let f: Foo;
+        f = Foo {};
+    }"#;
+
+        let refs = get_all_refs(code);
+        check_result(
+            refs,
+            "Foo STRUCT_DEF FileId(1) [5; 18) [12; 15) Other",
+            &["FileId(1) [54; 57) Other", "FileId(1) [71; 74) StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_struct_literal_with_generic_type() {
+        let code = r#"
+    struct Foo<T> <|>{}
+        fn main() {
+        let f: Foo::<i32>;
+        f = Foo {};
+    }"#;
+
+        let refs = get_all_refs(code);
+        check_result(
+            refs,
+            "Foo STRUCT_DEF FileId(1) [5; 21) [12; 15) Other",
+            &["FileId(1) [81; 84) StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_struct_literal_for_tuple() {
+        let code = r#"
+    struct Foo<|>(i32);
+
+    fn main() {
+        let f: Foo;
+        f = Foo(1);
+    }"#;
+
+        let refs = get_all_refs(code);
+        check_result(
+            refs,
+            "Foo STRUCT_DEF FileId(1) [5; 21) [12; 15) Other",
+            &["FileId(1) [71; 74) StructLiteral"],
+        );
+    }
+
+    #[test]
     fn test_find_all_refs_for_local() {
         let code = r#"
     fn main() {
@@ -564,7 +648,7 @@ mod tests {
         check_result(
             refs,
             "quux FN_DEF FileId(1) [18; 34) [25; 29) Other",
-            &["FileId(2) [16; 20) Other", "FileId(3) [16; 20) Other"],
+            &["FileId(2) [16; 20) StructLiteral", "FileId(3) [16; 20) StructLiteral"],
         );
 
         let refs =
@@ -572,7 +656,7 @@ mod tests {
         check_result(
             refs,
             "quux FN_DEF FileId(1) [18; 34) [25; 29) Other",
-            &["FileId(3) [16; 20) Other"],
+            &["FileId(3) [16; 20) StructLiteral"],
         );
     }
 
@@ -591,7 +675,7 @@ mod tests {
         check_result(
             refs,
             "m1 MACRO_CALL FileId(1) [9; 63) [46; 48) Other",
-            &["FileId(1) [96; 98) Other", "FileId(1) [114; 116) Other"],
+            &["FileId(1) [96; 98) StructLiteral", "FileId(1) [114; 116) StructLiteral"],
         );
     }
 
diff --git a/crates/ra_ide/src/runnables.rs b/crates/ra_ide/src/runnables.rs
index 7533692f6..8622dd956 100644
--- a/crates/ra_ide/src/runnables.rs
+++ b/crates/ra_ide/src/runnables.rs
@@ -43,7 +43,7 @@ fn runnable_fn(fn_def: ast::FnDef) -> Option<Runnable> {
     let name = fn_def.name()?.text().clone();
     let kind = if name == "main" {
         RunnableKind::Bin
-    } else if fn_def.has_atom_attr("test") {
+    } else if has_test_related_attribute(&fn_def) {
         RunnableKind::Test { name: name.to_string() }
     } else if fn_def.has_atom_attr("bench") {
         RunnableKind::Bench { name: name.to_string() }
@@ -53,6 +53,20 @@ fn runnable_fn(fn_def: ast::FnDef) -> Option<Runnable> {
     Some(Runnable { range: fn_def.syntax().text_range(), kind })
 }
 
+/// This is a method with a heuristics to support test methods annotated with custom test annotations, such as
+/// `#[test_case(...)]`, `#[tokio::test]` and similar.
+/// Also a regular `#[test]` annotation is supported.
+///
+/// It may produce false positives, for example, `#[wasm_bindgen_test]` requires a different command to run the test,
+/// but it's better than not to have the runnables for the tests at all.
+fn has_test_related_attribute(fn_def: &ast::FnDef) -> bool {
+    fn_def
+        .attrs()
+        .filter_map(|attr| attr.path())
+        .map(|path| path.syntax().to_string().to_lowercase())
+        .any(|attribute_text| attribute_text.contains("test"))
+}
+
 fn runnable_mod(db: &RootDatabase, file_id: FileId, module: ast::Module) -> Option<Runnable> {
     let has_test_function = module
         .item_list()?
diff --git a/crates/ra_ide/src/snapshots/highlighting.html b/crates/ra_ide/src/snapshots/highlighting.html
index 1d130544f..1cc55e78b 100644
--- a/crates/ra_ide/src/snapshots/highlighting.html
+++ b/crates/ra_ide/src/snapshots/highlighting.html
@@ -34,6 +34,16 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="function">foo</span>::&lt;<span class="type.builtin">i32</span>&gt;();
 }
 
+<span class="macro">macro_rules</span><span class="macro">!</span> def_fn {
+    ($($tt:tt)*) =&gt; {$($tt)*}
+}
+
+<span class="macro">def_fn</span><span class="macro">!</span>{
+    <span class="keyword">fn</span> <span class="function">bar</span>() -&gt; <span class="type.builtin">u32</span> {
+        <span class="literal.numeric">100</span>
+    }
+}
+
 <span class="comment">// comment</span>
 <span class="keyword">fn</span> <span class="function">main</span>() {
     <span class="macro">println</span><span class="macro">!</span>(<span class="string">"Hello, {}!"</span>, <span class="literal.numeric">92</span>);
diff --git a/crates/ra_ide/src/snapshots/rainbow_highlighting.html b/crates/ra_ide/src/snapshots/rainbow_highlighting.html
index d90ee8540..918fd4b97 100644
--- a/crates/ra_ide/src/snapshots/rainbow_highlighting.html
+++ b/crates/ra_ide/src/snapshots/rainbow_highlighting.html
@@ -24,14 +24,14 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .keyword\.control  { color: #F0DFAF; font-weight: bold; }
 </style>
 <pre><code><span class="keyword">fn</span> <span class="function">main</span>() {
-    <span class="keyword">let</span> <span class="variable" data-binding-hash="8723171760279909834" style="color: hsl(307,91%,75%);">hello</span> = <span class="string">"hello"</span>;
-    <span class="keyword">let</span> <span class="variable" data-binding-hash="14702933417323009544" style="color: hsl(108,90%,49%);">x</span> = <span class="variable" data-binding-hash="8723171760279909834" style="color: hsl(307,91%,75%);">hello</span>.to_string();
-    <span class="keyword">let</span> <span class="variable" data-binding-hash="5443150872754369068" style="color: hsl(215,43%,43%);">y</span> = <span class="variable" data-binding-hash="8723171760279909834" style="color: hsl(307,91%,75%);">hello</span>.to_string();
+    <span class="keyword">let</span> <span class="variable" data-binding-hash="2217585909179791122" style="color: hsl(280,74%,48%);">hello</span> = <span class="string">"hello"</span>;
+    <span class="keyword">let</span> <span class="variable" data-binding-hash="4303609361109701698" style="color: hsl(242,75%,88%);">x</span> = <span class="variable" data-binding-hash="2217585909179791122" style="color: hsl(280,74%,48%);">hello</span>.to_string();
+    <span class="keyword">let</span> <span class="variable" data-binding-hash="13865792086344377029" style="color: hsl(340,64%,86%);">y</span> = <span class="variable" data-binding-hash="2217585909179791122" style="color: hsl(280,74%,48%);">hello</span>.to_string();
 
-    <span class="keyword">let</span> <span class="variable" data-binding-hash="17358108296605513516" style="color: hsl(331,46%,60%);">x</span> = <span class="string">"other color please!"</span>;
-    <span class="keyword">let</span> <span class="variable" data-binding-hash="2073121142529774969" style="color: hsl(320,43%,74%);">y</span> = <span class="variable" data-binding-hash="17358108296605513516" style="color: hsl(331,46%,60%);">x</span>.to_string();
+    <span class="keyword">let</span> <span class="variable" data-binding-hash="7011301204224269512" style="color: hsl(198,45%,40%);">x</span> = <span class="string">"other color please!"</span>;
+    <span class="keyword">let</span> <span class="variable" data-binding-hash="12461245066629867975" style="color: hsl(132,91%,68%);">y</span> = <span class="variable" data-binding-hash="7011301204224269512" style="color: hsl(198,45%,40%);">x</span>.to_string();
 }
 
 <span class="keyword">fn</span> <span class="function">bar</span>() {
-    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable.mut" data-binding-hash="8723171760279909834" style="color: hsl(307,91%,75%);">hello</span> = <span class="string">"hello"</span>;
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable.mut" data-binding-hash="2217585909179791122" style="color: hsl(280,74%,48%);">hello</span> = <span class="string">"hello"</span>;
 }</code></pre>
\ No newline at end of file
diff --git a/crates/ra_ide/src/syntax_highlighting.rs b/crates/ra_ide/src/syntax_highlighting.rs
index 0411977b9..530b984fc 100644
--- a/crates/ra_ide/src/syntax_highlighting.rs
+++ b/crates/ra_ide/src/syntax_highlighting.rs
@@ -1,14 +1,18 @@
 //! FIXME: write short doc here
 
-use rustc_hash::{FxHashMap, FxHashSet};
+use rustc_hash::FxHashMap;
 
-use hir::{InFile, Name, SourceBinder};
+use hir::{HirFileId, InFile, Name, SourceAnalyzer, SourceBinder};
 use ra_db::SourceDatabase;
 use ra_prof::profile;
-use ra_syntax::{ast, AstNode, Direction, SyntaxElement, SyntaxKind, SyntaxKind::*, TextRange, T};
+use ra_syntax::{
+    ast, AstNode, Direction, SyntaxElement, SyntaxKind, SyntaxKind::*, SyntaxToken, TextRange,
+    WalkEvent, T,
+};
 
 use crate::{
     db::RootDatabase,
+    expand::descend_into_macros_with_analyzer,
     references::{
         classify_name, classify_name_ref,
         NameKind::{self, *},
@@ -72,121 +76,186 @@ pub(crate) fn highlight(db: &RootDatabase, file_id: FileId) -> Vec<HighlightedRa
     let parse = db.parse(file_id);
     let root = parse.tree().syntax().clone();
 
-    fn calc_binding_hash(file_id: FileId, name: &Name, shadow_count: u32) -> u64 {
-        fn hash<T: std::hash::Hash + std::fmt::Debug>(x: T) -> u64 {
-            use std::{collections::hash_map::DefaultHasher, hash::Hasher};
+    let mut sb = SourceBinder::new(db);
+    let mut bindings_shadow_count: FxHashMap<Name, u32> = FxHashMap::default();
+    let mut res = Vec::new();
+    let analyzer = sb.analyze(InFile::new(file_id.into(), &root), None);
 
-            let mut hasher = DefaultHasher::new();
-            x.hash(&mut hasher);
-            hasher.finish()
+    let mut in_macro_call = None;
+
+    for event in root.preorder_with_tokens() {
+        match event {
+            WalkEvent::Enter(node) => match node.kind() {
+                MACRO_CALL => {
+                    in_macro_call = Some(node.clone());
+                    if let Some(range) = highlight_macro(InFile::new(file_id.into(), node)) {
+                        res.push(HighlightedRange { range, tag: tags::MACRO, binding_hash: None });
+                    }
+                }
+                _ if in_macro_call.is_some() => {
+                    if let Some(token) = node.as_token() {
+                        if let Some((tag, binding_hash)) = highlight_token_tree(
+                            db,
+                            &mut sb,
+                            &analyzer,
+                            &mut bindings_shadow_count,
+                            InFile::new(file_id.into(), token.clone()),
+                        ) {
+                            res.push(HighlightedRange {
+                                range: node.text_range(),
+                                tag,
+                                binding_hash,
+                            });
+                        }
+                    }
+                }
+                _ => {
+                    if let Some((tag, binding_hash)) = highlight_node(
+                        db,
+                        &mut sb,
+                        &mut bindings_shadow_count,
+                        InFile::new(file_id.into(), node.clone()),
+                    ) {
+                        res.push(HighlightedRange { range: node.text_range(), tag, binding_hash });
+                    }
+                }
+            },
+            WalkEvent::Leave(node) => {
+                if let Some(m) = in_macro_call.as_ref() {
+                    if *m == node {
+                        in_macro_call = None;
+                    }
+                }
+            }
         }
+    }
 
-        hash((file_id, name, shadow_count))
+    res
+}
+
+fn highlight_macro(node: InFile<SyntaxElement>) -> Option<TextRange> {
+    let macro_call = ast::MacroCall::cast(node.value.as_node()?.clone())?;
+    let path = macro_call.path()?;
+    let name_ref = path.segment()?.name_ref()?;
+
+    let range_start = name_ref.syntax().text_range().start();
+    let mut range_end = name_ref.syntax().text_range().end();
+    for sibling in path.syntax().siblings_with_tokens(Direction::Next) {
+        match sibling.kind() {
+            T![!] | IDENT => range_end = sibling.text_range().end(),
+            _ => (),
+        }
     }
 
-    let mut sb = SourceBinder::new(db);
+    Some(TextRange::from_to(range_start, range_end))
+}
 
-    // Visited nodes to handle highlighting priorities
-    // FIXME: retain only ranges here
-    let mut highlighted: FxHashSet<SyntaxElement> = FxHashSet::default();
-    let mut bindings_shadow_count: FxHashMap<Name, u32> = FxHashMap::default();
+fn highlight_token_tree(
+    db: &RootDatabase,
+    sb: &mut SourceBinder<RootDatabase>,
+    analyzer: &SourceAnalyzer,
+    bindings_shadow_count: &mut FxHashMap<Name, u32>,
+    token: InFile<SyntaxToken>,
+) -> Option<(&'static str, Option<u64>)> {
+    if token.value.parent().kind() != TOKEN_TREE {
+        return None;
+    }
+    let token = descend_into_macros_with_analyzer(db, analyzer, token);
+    let expanded = {
+        let parent = token.value.parent();
+        // We only care Name and Name_ref
+        match (token.value.kind(), parent.kind()) {
+            (IDENT, NAME) | (IDENT, NAME_REF) => token.with_value(parent.into()),
+            _ => token.map(|it| it.into()),
+        }
+    };
 
-    let mut res = Vec::new();
-    for node in root.descendants_with_tokens() {
-        if highlighted.contains(&node) {
-            continue;
+    highlight_node(db, sb, bindings_shadow_count, expanded)
+}
+
+fn highlight_node(
+    db: &RootDatabase,
+    sb: &mut SourceBinder<RootDatabase>,
+    bindings_shadow_count: &mut FxHashMap<Name, u32>,
+    node: InFile<SyntaxElement>,
+) -> Option<(&'static str, Option<u64>)> {
+    let mut binding_hash = None;
+    let tag = match node.value.kind() {
+        FN_DEF => {
+            bindings_shadow_count.clear();
+            return None;
         }
-        let mut binding_hash = None;
-        let tag = match node.kind() {
-            FN_DEF => {
-                bindings_shadow_count.clear();
-                continue;
-            }
-            COMMENT => tags::LITERAL_COMMENT,
-            STRING | RAW_STRING | RAW_BYTE_STRING | BYTE_STRING => tags::LITERAL_STRING,
-            ATTR => tags::LITERAL_ATTRIBUTE,
-            // Special-case field init shorthand
-            NAME_REF if node.parent().and_then(ast::RecordField::cast).is_some() => tags::FIELD,
-            NAME_REF if node.ancestors().any(|it| it.kind() == ATTR) => continue,
-            NAME_REF => {
-                let name_ref = node.as_node().cloned().and_then(ast::NameRef::cast).unwrap();
-                let name_kind = classify_name_ref(&mut sb, InFile::new(file_id.into(), &name_ref))
-                    .map(|d| d.kind);
-                match name_kind {
-                    Some(name_kind) => {
-                        if let Local(local) = &name_kind {
-                            if let Some(name) = local.name(db) {
-                                let shadow_count =
-                                    bindings_shadow_count.entry(name.clone()).or_default();
-                                binding_hash =
-                                    Some(calc_binding_hash(file_id, &name, *shadow_count))
-                            }
-                        };
-
-                        highlight_name(db, name_kind)
-                    }
-                    _ => continue,
-                }
-            }
-            NAME => {
-                let name = node.as_node().cloned().and_then(ast::Name::cast).unwrap();
-                let name_kind =
-                    classify_name(&mut sb, InFile::new(file_id.into(), &name)).map(|d| d.kind);
-
-                if let Some(Local(local)) = &name_kind {
-                    if let Some(name) = local.name(db) {
-                        let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
-                        *shadow_count += 1;
-                        binding_hash = Some(calc_binding_hash(file_id, &name, *shadow_count))
-                    }
-                };
-
-                match name_kind {
-                    Some(name_kind) => highlight_name(db, name_kind),
-                    None => name.syntax().parent().map_or(tags::FUNCTION, |x| match x.kind() {
-                        STRUCT_DEF | ENUM_DEF | TRAIT_DEF | TYPE_ALIAS_DEF => tags::TYPE,
-                        TYPE_PARAM => tags::TYPE_PARAM,
-                        RECORD_FIELD_DEF => tags::FIELD,
-                        _ => tags::FUNCTION,
-                    }),
+        COMMENT => tags::LITERAL_COMMENT,
+        STRING | RAW_STRING | RAW_BYTE_STRING | BYTE_STRING => tags::LITERAL_STRING,
+        ATTR => tags::LITERAL_ATTRIBUTE,
+        // Special-case field init shorthand
+        NAME_REF if node.value.parent().and_then(ast::RecordField::cast).is_some() => tags::FIELD,
+        NAME_REF if node.value.ancestors().any(|it| it.kind() == ATTR) => return None,
+        NAME_REF => {
+            let name_ref = node.value.as_node().cloned().and_then(ast::NameRef::cast).unwrap();
+            let name_kind = classify_name_ref(sb, node.with_value(&name_ref)).map(|d| d.kind);
+            match name_kind {
+                Some(name_kind) => {
+                    if let Local(local) = &name_kind {
+                        if let Some(name) = local.name(db) {
+                            let shadow_count =
+                                bindings_shadow_count.entry(name.clone()).or_default();
+                            binding_hash =
+                                Some(calc_binding_hash(node.file_id, &name, *shadow_count))
+                        }
+                    };
+
+                    highlight_name(db, name_kind)
                 }
+                _ => return None,
             }
-            INT_NUMBER | FLOAT_NUMBER => tags::LITERAL_NUMERIC,
-            BYTE => tags::LITERAL_BYTE,
-            CHAR => tags::LITERAL_CHAR,
-            LIFETIME => tags::TYPE_LIFETIME,
-            T![unsafe] => tags::KEYWORD_UNSAFE,
-            k if is_control_keyword(k) => tags::KEYWORD_CONTROL,
-            k if k.is_keyword() => tags::KEYWORD,
-            _ => {
-                if let Some(macro_call) = node.as_node().cloned().and_then(ast::MacroCall::cast) {
-                    if let Some(path) = macro_call.path() {
-                        if let Some(segment) = path.segment() {
-                            if let Some(name_ref) = segment.name_ref() {
-                                highlighted.insert(name_ref.syntax().clone().into());
-                                let range_start = name_ref.syntax().text_range().start();
-                                let mut range_end = name_ref.syntax().text_range().end();
-                                for sibling in path.syntax().siblings_with_tokens(Direction::Next) {
-                                    match sibling.kind() {
-                                        T![!] | IDENT => range_end = sibling.text_range().end(),
-                                        _ => (),
-                                    }
-                                }
-                                res.push(HighlightedRange {
-                                    range: TextRange::from_to(range_start, range_end),
-                                    tag: tags::MACRO,
-                                    binding_hash: None,
-                                })
-                            }
-                        }
-                    }
+        }
+        NAME => {
+            let name = node.value.as_node().cloned().and_then(ast::Name::cast).unwrap();
+            let name_kind = classify_name(sb, node.with_value(&name)).map(|d| d.kind);
+
+            if let Some(Local(local)) = &name_kind {
+                if let Some(name) = local.name(db) {
+                    let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
+                    *shadow_count += 1;
+                    binding_hash = Some(calc_binding_hash(node.file_id, &name, *shadow_count))
                 }
-                continue;
+            };
+
+            match name_kind {
+                Some(name_kind) => highlight_name(db, name_kind),
+                None => name.syntax().parent().map_or(tags::FUNCTION, |x| match x.kind() {
+                    STRUCT_DEF | ENUM_DEF | TRAIT_DEF | TYPE_ALIAS_DEF => tags::TYPE,
+                    TYPE_PARAM => tags::TYPE_PARAM,
+                    RECORD_FIELD_DEF => tags::FIELD,
+                    _ => tags::FUNCTION,
+                }),
             }
-        };
-        res.push(HighlightedRange { range: node.text_range(), tag, binding_hash })
+        }
+        INT_NUMBER | FLOAT_NUMBER => tags::LITERAL_NUMERIC,
+        BYTE => tags::LITERAL_BYTE,
+        CHAR => tags::LITERAL_CHAR,
+        LIFETIME => tags::TYPE_LIFETIME,
+        T![unsafe] => tags::KEYWORD_UNSAFE,
+        k if is_control_keyword(k) => tags::KEYWORD_CONTROL,
+        k if k.is_keyword() => tags::KEYWORD,
+
+        _ => return None,
+    };
+
+    return Some((tag, binding_hash));
+
+    fn calc_binding_hash(file_id: HirFileId, name: &Name, shadow_count: u32) -> u64 {
+        fn hash<T: std::hash::Hash + std::fmt::Debug>(x: T) -> u64 {
+            use std::{collections::hash_map::DefaultHasher, hash::Hasher};
+
+            let mut hasher = DefaultHasher::new();
+            x.hash(&mut hasher);
+            hasher.finish()
+        }
+
+        hash((file_id, name, shadow_count))
     }
-    res
 }
 
 pub(crate) fn highlight_as_html(db: &RootDatabase, file_id: FileId, rainbow: bool) -> String {
@@ -331,6 +400,16 @@ fn foo<T>() -> T {
     foo::<i32>();
 }
 
+macro_rules! def_fn {
+    ($($tt:tt)*) => {$($tt)*}
+}
+
+def_fn!{
+    fn bar() -> u32 {
+        100
+    }
+}
+
 // comment
 fn main() {
     println!("Hello, {}!", 92);
diff --git a/crates/ra_lsp_server/Cargo.toml b/crates/ra_lsp_server/Cargo.toml
index 579158780..fdf81ed87 100644
--- a/crates/ra_lsp_server/Cargo.toml
+++ b/crates/ra_lsp_server/Cargo.toml
@@ -14,7 +14,7 @@ serde_json = "1.0.34"
 serde = { version = "1.0.83", features = ["derive"] }
 crossbeam-channel = "0.4"
 log = "0.4.3"
-lsp-types = { version = "0.69.0", features = ["proposed"] }
+lsp-types = { version = "0.70.0", features = ["proposed"] }
 rustc-hash = "1.0"
 parking_lot = "0.10.0"
 jod-thread = "0.1.0"
@@ -26,10 +26,13 @@ lsp-server = "0.3.0"
 ra_project_model = { path = "../ra_project_model" }
 ra_prof = { path = "../ra_prof" }
 ra_vfs_glob = { path = "../ra_vfs_glob" }
-env_logger = { version = "0.7.1", default-features = false, features = ["humantime"] }
+env_logger = { version = "0.7.1", default-features = false }
 ra_cargo_watch = { path = "../ra_cargo_watch" }
 either = "1.5"
 
+[target.'cfg(windows)'.dependencies]
+winapi = "0.3"
+
 [dev-dependencies]
 tempfile = "3"
 test_utils = { path = "../test_utils" }
diff --git a/crates/ra_lsp_server/src/main_loop.rs b/crates/ra_lsp_server/src/main_loop.rs
index 7822be2e2..d850ded37 100644
--- a/crates/ra_lsp_server/src/main_loop.rs
+++ b/crates/ra_lsp_server/src/main_loop.rs
@@ -5,11 +5,18 @@ mod handlers;
 mod subscriptions;
 pub(crate) mod pending_requests;
 
-use std::{error::Error, fmt, panic, path::PathBuf, sync::Arc, time::Instant};
+use std::{
+    env,
+    error::Error,
+    fmt, panic,
+    path::PathBuf,
+    sync::Arc,
+    time::{Duration, Instant},
+};
 
 use crossbeam_channel::{select, unbounded, RecvError, Sender};
 use lsp_server::{Connection, ErrorCode, Message, Notification, Request, RequestId, Response};
-use lsp_types::{ClientCapabilities, NumberOrString, Url};
+use lsp_types::{ClientCapabilities, NumberOrString};
 use ra_cargo_watch::{CheckOptions, CheckTask};
 use ra_ide::{Canceled, FeatureFlags, FileId, LibraryData, SourceRootId};
 use ra_prof::profile;
@@ -29,9 +36,6 @@ use crate::{
     Result, ServerConfig,
 };
 
-const THREADPOOL_SIZE: usize = 8;
-const MAX_IN_FLIGHT_LIBS: usize = THREADPOOL_SIZE - 3;
-
 #[derive(Debug)]
 pub struct LspError {
     pub code: i32,
@@ -60,6 +64,25 @@ pub fn main_loop(
 ) -> Result<()> {
     log::info!("server_config: {:#?}", config);
 
+    // Windows scheduler implements priority boosts: if thread waits for an
+    // event (like a condvar), and event fires, priority of the thread is
+    // temporary bumped. This optimization backfires in our case: each time the
+    // `main_loop` schedules a task to run on a threadpool, the worker threads
+    // gets a higher priority, and (on a machine with fewer cores) displaces the
+    // main loop! We work-around this by marking the main loop as a
+    // higher-priority thread.
+    //
+    // https://docs.microsoft.com/en-us/windows/win32/procthread/scheduling-priorities
+    // https://docs.microsoft.com/en-us/windows/win32/procthread/priority-boosts
+    // https://github.com/rust-analyzer/rust-analyzer/issues/2835
+    #[cfg(windows)]
+    unsafe {
+        use winapi::um::processthreadsapi::*;
+        let thread = GetCurrentThread();
+        let thread_priority_above_normal = 1;
+        SetThreadPriority(thread, thread_priority_above_normal);
+    }
+
     let mut loop_state = LoopState::default();
     let mut world_state = {
         let feature_flags = {
@@ -168,7 +191,7 @@ pub fn main_loop(
         )
     };
 
-    let pool = ThreadPool::new(THREADPOOL_SIZE);
+    let pool = ThreadPool::default();
     let (task_sender, task_receiver) = unbounded::<Task>();
     let (libdata_sender, libdata_receiver) = unbounded::<LibraryData>();
 
@@ -210,7 +233,7 @@ pub fn main_loop(
             )?;
         }
     }
-
+    world_state.analysis_host.request_cancellation();
     log::info!("waiting for tasks to finish...");
     task_receiver.into_iter().for_each(|task| {
         on_task(task, &connection.sender, &mut loop_state.pending_requests, &mut world_state)
@@ -336,7 +359,7 @@ fn loop_turn(
             world_state.maybe_collect_garbage();
             loop_state.in_flight_libraries -= 1;
         }
-        Event::CheckWatcher(task) => on_check_task(task, world_state, task_sender)?,
+        Event::CheckWatcher(task) => on_check_task(pool, task, world_state, task_sender)?,
         Event::Msg(msg) => match msg {
             Message::Request(req) => on_request(
                 world_state,
@@ -371,7 +394,8 @@ fn loop_turn(
         loop_state.pending_libraries.extend(changes);
     }
 
-    while loop_state.in_flight_libraries < MAX_IN_FLIGHT_LIBS
+    let max_in_flight_libs = pool.max_count().saturating_sub(2).max(1);
+    while loop_state.in_flight_libraries < max_in_flight_libs
         && !loop_state.pending_libraries.is_empty()
     {
         let (root, files) = loop_state.pending_libraries.pop().unwrap();
@@ -408,6 +432,19 @@ fn loop_turn(
             loop_state.subscriptions.subscriptions(),
         )
     }
+
+    let loop_duration = loop_start.elapsed();
+    if loop_duration > Duration::from_millis(100) {
+        log::error!("overly long loop turn: {:?}", loop_duration);
+        if env::var("RA_PROFILE").is_ok() {
+            show_message(
+                req::MessageType::Error,
+                format!("overly long loop turn: {:?}", loop_duration),
+                &connection.sender,
+            );
+        }
+    }
+
     Ok(())
 }
 
@@ -435,7 +472,7 @@ fn on_request(
     world: &mut WorldState,
     pending_requests: &mut PendingRequests,
     pool: &ThreadPool,
-    sender: &Sender<Task>,
+    task_sender: &Sender<Task>,
     msg_sender: &Sender<Message>,
     request_received: Instant,
     req: Request,
@@ -444,7 +481,7 @@ fn on_request(
         req: Some(req),
         pool,
         world,
-        sender,
+        task_sender,
         msg_sender,
         pending_requests,
         request_received,
@@ -585,31 +622,23 @@ fn on_notification(
 }
 
 fn on_check_task(
+    pool: &ThreadPool,
     task: CheckTask,
-    world_state: &WorldState,
+    world_state: &mut WorldState,
     task_sender: &Sender<Task>,
 ) -> Result<()> {
-    match task {
+    let urls = match task {
         CheckTask::ClearDiagnostics => {
-            let cleared_files = world_state.check_watcher.state.write().clear();
-
-            // Send updated diagnostics for each cleared file
-            for url in cleared_files {
-                publish_diagnostics_for_url(&url, world_state, task_sender)?;
-            }
+            let state = Arc::get_mut(&mut world_state.check_watcher.state)
+                .expect("couldn't get check watcher state as mutable");
+            state.clear()
         }
 
         CheckTask::AddDiagnostic(url, diagnostic) => {
-            world_state
-                .check_watcher
-                .state
-                .write()
-                .add_diagnostic_with_fixes(url.clone(), diagnostic);
-
-            // We manually send a diagnostic update when the watcher asks
-            // us to, to avoid the issue of having to change the file to
-            // receive updated diagnostics.
-            publish_diagnostics_for_url(&url, world_state, task_sender)?;
+            let state = Arc::get_mut(&mut world_state.check_watcher.state)
+                .expect("couldn't get check watcher state as mutable");
+            state.add_diagnostic_with_fixes(url.clone(), diagnostic);
+            vec![url]
         }
 
         CheckTask::Status(progress) => {
@@ -619,22 +648,30 @@ fn on_check_task(
             };
             let not = notification_new::<req::Progress>(params);
             task_sender.send(Task::Notify(not)).unwrap();
+            Vec::new()
         }
-    }
-    Ok(())
-}
+    };
+
+    let subscriptions = urls
+        .into_iter()
+        .map(|url| {
+            let path = url.to_file_path().map_err(|()| format!("invalid uri: {}", url))?;
+            Ok(world_state.vfs.read().path2file(&path).map(|it| FileId(it.0)))
+        })
+        .filter_map(|res| res.transpose())
+        .collect::<Result<Vec<_>>>()?;
+
+    // We manually send a diagnostic update when the watcher asks
+    // us to, to avoid the issue of having to change the file to
+    // receive updated diagnostics.
+    update_file_notifications_on_threadpool(
+        pool,
+        world_state.snapshot(),
+        false,
+        task_sender.clone(),
+        subscriptions,
+    );
 
-fn publish_diagnostics_for_url(
-    url: &Url,
-    world_state: &WorldState,
-    task_sender: &Sender<Task>,
-) -> Result<()> {
-    let path = url.to_file_path().map_err(|()| format!("invalid uri: {}", url))?;
-    if let Some(file_id) = world_state.vfs.read().path2file(&path) {
-        let params = handlers::publish_diagnostics(&world_state.snapshot(), FileId(file_id.0))?;
-        let not = notification_new::<req::PublishDiagnostics>(params);
-        task_sender.send(Task::Notify(not)).unwrap();
-    }
     Ok(())
 }
 
@@ -644,7 +681,7 @@ struct PoolDispatcher<'a> {
     world: &'a mut WorldState,
     pending_requests: &'a mut PendingRequests,
     msg_sender: &'a Sender<Message>,
-    sender: &'a Sender<Task>,
+    task_sender: &'a Sender<Task>,
     request_received: Instant,
 }
 
@@ -691,7 +728,7 @@ impl<'a> PoolDispatcher<'a> {
 
         self.pool.execute({
             let world = self.world.snapshot();
-            let sender = self.sender.clone();
+            let sender = self.task_sender.clone();
             move || {
                 let result = f(world, params);
                 let task = result_to_task::<R>(id, result);
@@ -769,7 +806,7 @@ fn update_file_notifications_on_threadpool(
     pool: &ThreadPool,
     world: WorldSnapshot,
     publish_decorations: bool,
-    sender: Sender<Task>,
+    task_sender: Sender<Task>,
     subscriptions: Vec<FileId>,
 ) {
     log::trace!("updating notifications for {:?}", subscriptions);
@@ -785,7 +822,7 @@ fn update_file_notifications_on_threadpool(
                     }
                     Ok(params) => {
                         let not = notification_new::<req::PublishDiagnostics>(params);
-                        sender.send(Task::Notify(not)).unwrap();
+                        task_sender.send(Task::Notify(not)).unwrap();
                     }
                 }
             }
@@ -798,7 +835,7 @@ fn update_file_notifications_on_threadpool(
                     }
                     Ok(params) => {
                         let not = notification_new::<req::PublishDecorations>(params);
-                        sender.send(Task::Notify(not)).unwrap();
+                        task_sender.send(Task::Notify(not)).unwrap();
                     }
                 }
             }
diff --git a/crates/ra_lsp_server/src/main_loop/handlers.rs b/crates/ra_lsp_server/src/main_loop/handlers.rs
index 8e43f0575..666f2ee29 100644
--- a/crates/ra_lsp_server/src/main_loop/handlers.rs
+++ b/crates/ra_lsp_server/src/main_loop/handlers.rs
@@ -674,8 +674,7 @@ pub fn handle_code_action(
         res.push(action.into());
     }
 
-    for fix in world.check_watcher.read().fixes_for(&params.text_document.uri).into_iter().flatten()
-    {
+    for fix in world.check_watcher.fixes_for(&params.text_document.uri).into_iter().flatten() {
         let fix_range = fix.location.range.conv_with(&line_index);
         if fix_range.intersection(&range).is_none() {
             continue;
@@ -895,7 +894,7 @@ pub fn publish_diagnostics(
             tags: None,
         })
         .collect();
-    if let Some(check_diags) = world.check_watcher.read().diagnostics_for(&uri) {
+    if let Some(check_diags) = world.check_watcher.diagnostics_for(&uri) {
         diagnostics.extend(check_diags.iter().cloned());
     }
     Ok(req::PublishDiagnosticsParams { uri, diagnostics, version: None })
diff --git a/crates/ra_lsp_server/src/world.rs b/crates/ra_lsp_server/src/world.rs
index e7a0acfc7..3059ef9ec 100644
--- a/crates/ra_lsp_server/src/world.rs
+++ b/crates/ra_lsp_server/src/world.rs
@@ -63,7 +63,7 @@ pub struct WorldSnapshot {
     pub workspaces: Arc<Vec<ProjectWorkspace>>,
     pub analysis: Analysis,
     pub latest_requests: Arc<RwLock<LatestRequests>>,
-    pub check_watcher: Arc<RwLock<CheckState>>,
+    pub check_watcher: CheckState,
     vfs: Arc<RwLock<Vfs>>,
 }
 
@@ -220,7 +220,7 @@ impl WorldState {
             analysis: self.analysis_host.analysis(),
             vfs: Arc::clone(&self.vfs),
             latest_requests: Arc::clone(&self.latest_requests),
-            check_watcher: self.check_watcher.state.clone(),
+            check_watcher: (*self.check_watcher.state).clone(),
         }
     }
 
diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
index e2c32c130..4a49e9f95 100644
--- a/crates/ra_prof/src/lib.rs
+++ b/crates/ra_prof/src/lib.rs
@@ -105,6 +105,21 @@ pub fn profile(desc: &str) -> Profiler {
     })
 }
 
+pub fn print_time(desc: &str) -> impl Drop + '_ {
+    struct Guard<'a> {
+        desc: &'a str,
+        start: Instant,
+    }
+
+    impl Drop for Guard<'_> {
+        fn drop(&mut self) {
+            eprintln!("{}: {:?}", self.desc, self.start.elapsed())
+        }
+    }
+
+    Guard { desc, start: Instant::now() }
+}
+
 pub struct Profiler {
     desc: Option<String>,
 }
diff --git a/crates/test_utils/src/lib.rs b/crates/test_utils/src/lib.rs
index 659f77b71..5666445aa 100644
--- a/crates/test_utils/src/lib.rs
+++ b/crates/test_utils/src/lib.rs
@@ -21,6 +21,12 @@ pub use difference::Changeset as __Changeset;
 
 pub const CURSOR_MARKER: &str = "<|>";
 
+/// Asserts that two strings are equal, otherwise displays a rich diff between them.
+///
+/// The diff shows changes from the "original" left string to the "actual" right string.
+///
+/// All arguments starting from and including the 3rd one are passed to
+/// `eprintln!()` macro in case of text inequality.
 #[macro_export]
 macro_rules! assert_eq_text {
     ($left:expr, $right:expr) => {
@@ -42,6 +48,7 @@ macro_rules! assert_eq_text {
     }};
 }
 
+/// Infallible version of `try_extract_offset()`.
 pub fn extract_offset(text: &str) -> (TextUnit, String) {
     match try_extract_offset(text) {
         None => panic!("text should contain cursor marker"),
@@ -49,6 +56,8 @@ pub fn extract_offset(text: &str) -> (TextUnit, String) {
     }
 }
 
+/// Returns the offset of the first occurence of `<|>` marker and the copy of `text`
+/// without the marker.
 fn try_extract_offset(text: &str) -> Option<(TextUnit, String)> {
     let cursor_pos = text.find(CURSOR_MARKER)?;
     let mut new_text = String::with_capacity(text.len() - CURSOR_MARKER.len());
@@ -58,6 +67,7 @@ fn try_extract_offset(text: &str) -> Option<(TextUnit, String)> {
     Some((cursor_pos, new_text))
 }
 
+/// Infallible version of `try_extract_range()`.
 pub fn extract_range(text: &str) -> (TextRange, String) {
     match try_extract_range(text) {
         None => panic!("text should contain cursor marker"),
@@ -65,6 +75,8 @@ pub fn extract_range(text: &str) -> (TextRange, String) {
     }
 }
 
+/// Returns `TextRange` between the first two markers `<|>...<|>` and the copy
+/// of `text` without both of these markers.
 fn try_extract_range(text: &str) -> Option<(TextRange, String)> {
     let (start, text) = try_extract_offset(text)?;
     let (end, text) = try_extract_offset(&text)?;
@@ -85,6 +97,11 @@ impl From<RangeOrOffset> for TextRange {
     }
 }
 
+/// Extracts `TextRange` or `TextUnit` depending on the amount of `<|>` markers
+/// found in `text`.
+///
+/// # Panics
+/// Panics if no `<|>` marker is present in the `text`.
 pub fn extract_range_or_offset(text: &str) -> (RangeOrOffset, String) {
     if let Some((range, text)) = try_extract_range(text) {
         return (RangeOrOffset::Range(range), text);
@@ -93,7 +110,7 @@ pub fn extract_range_or_offset(text: &str) -> (RangeOrOffset, String) {
     (RangeOrOffset::Offset(offset), text)
 }
 
-/// Extracts ranges, marked with `<tag> </tag>` paris from the `text`
+/// Extracts ranges, marked with `<tag> </tag>` pairs from the `text`
 pub fn extract_ranges(mut text: &str, tag: &str) -> (Vec<TextRange>, String) {
     let open = format!("<{}>", tag);
     let close = format!("</{}>", tag);
@@ -127,9 +144,9 @@ pub fn extract_ranges(mut text: &str, tag: &str) -> (Vec<TextRange>, String) {
     (ranges, res)
 }
 
+/// Inserts `<|>` marker into the `text` at `offset`.
 pub fn add_cursor(text: &str, offset: TextUnit) -> String {
-    let offset: u32 = offset.into();
-    let offset: usize = offset as usize;
+    let offset: usize = offset.to_usize();
     let mut res = String::new();
     res.push_str(&text[..offset]);
     res.push_str("<|>");
@@ -152,19 +169,6 @@ pub struct FixtureEntry {
 ///  // - other meta
 ///  ```
 pub fn parse_fixture(fixture: &str) -> Vec<FixtureEntry> {
-    let mut res = Vec::new();
-    let mut buf = String::new();
-    let mut meta: Option<&str> = None;
-
-    macro_rules! flush {
-        () => {
-            if let Some(meta) = meta {
-                res.push(FixtureEntry { meta: meta.to_string(), text: buf.clone() });
-                buf.clear();
-            }
-        };
-    };
-
     let margin = fixture
         .lines()
         .filter(|it| it.trim_start().starts_with("//-"))
@@ -172,7 +176,7 @@ pub fn parse_fixture(fixture: &str) -> Vec<FixtureEntry> {
         .next()
         .expect("empty fixture");
 
-    let lines = fixture
+    let mut lines = fixture
         .split('\n') // don't use `.lines` to not drop `\r\n`
         .filter_map(|line| {
             if line.len() >= margin {
@@ -184,17 +188,29 @@ pub fn parse_fixture(fixture: &str) -> Vec<FixtureEntry> {
             }
         });
 
-    for line in lines {
-        if line.starts_with("//-") {
-            flush!();
-            buf.clear();
-            meta = Some(line["//-".len()..].trim());
-            continue;
+    let mut res = Vec::new();
+    let mut meta = None;
+    loop {
+        let mut next_meta = None;
+        let mut text = String::new();
+        for line in lines.by_ref() {
+            if line.starts_with("//-") {
+                next_meta = Some(line["//-".len()..].trim().to_string());
+                break;
+            }
+            text.push_str(line);
+            text.push('\n');
+        }
+
+        if let Some(meta) = meta {
+            res.push(FixtureEntry { meta, text });
+        }
+        meta = next_meta;
+        if meta.is_none() {
+            break;
         }
-        buf.push_str(line);
-        buf.push('\n');
     }
-    flush!();
+
     res
 }
 
@@ -236,11 +252,10 @@ fn lines_match_works() {
     assert!(!lines_match("b", "cb"));
 }
 
-// Compares JSON object for approximate equality.
-// You can use `[..]` wildcard in strings (useful for OS dependent things such
-// as paths).  You can use a `"{...}"` string literal as a wildcard for
-// arbitrary nested JSON (useful for parts of object emitted by other programs
-// (e.g. rustc) rather than Cargo itself).  Arrays are sorted before comparison.
+/// Compares JSON object for approximate equality.
+/// You can use `[..]` wildcard in strings (useful for OS dependent things such
+/// as paths). You can use a `"{...}"` string literal as a wildcard for
+/// arbitrary nested JSON. Arrays are sorted before comparison.
 pub fn find_mismatch<'a>(expected: &'a Value, actual: &'a Value) -> Option<(&'a Value, &'a Value)> {
     use serde_json::Value::*;
     match (expected, actual) {
@@ -286,6 +301,14 @@ pub fn find_mismatch<'a>(expected: &'a Value, actual: &'a Value) -> Option<(&'a
     }
 }
 
+/// Calls callback `f` with input code and file paths of all `.rs` files from `test_data_dir`
+/// subdirectories defined by `paths`.
+///
+/// If the content of the matching `.txt` file differs from the output of `f()`
+/// the test will fail.
+///
+/// If there is no matching `.txt` file it will be created and filled with the
+/// output of `f()`, but the test will fail.
 pub fn dir_tests<F>(test_data_dir: &Path, paths: &[&str], f: F)
 where
     F: Fn(&str, &Path) -> String,
@@ -307,6 +330,7 @@ where
     }
 }
 
+/// Collects all `.rs` files from `test_data_dir` subdirectories defined by `paths`.
 pub fn collect_tests(test_data_dir: &Path, paths: &[&str]) -> Vec<(PathBuf, String)> {
     paths
         .iter()
@@ -321,6 +345,7 @@ pub fn collect_tests(test_data_dir: &Path, paths: &[&str]) -> Vec<(PathBuf, Stri
         .collect()
 }
 
+/// Collects paths to all `.rs` files from `dir` in a sorted `Vec<PathBuf>`.
 fn test_from_dir(dir: &Path) -> Vec<PathBuf> {
     let mut acc = Vec::new();
     for file in fs::read_dir(&dir).unwrap() {
@@ -334,6 +359,7 @@ fn test_from_dir(dir: &Path) -> Vec<PathBuf> {
     acc
 }
 
+/// Returns the path to the root directory of `rust-analyzer` project.
 pub fn project_dir() -> PathBuf {
     let dir = env!("CARGO_MANIFEST_DIR");
     PathBuf::from(dir).parent().unwrap().parent().unwrap().to_owned()
@@ -356,6 +382,9 @@ pub fn read_text(path: &Path) -> String {
         .replace("\r\n", "\n")
 }
 
+/// Returns `false` if slow tests should not run, otherwise returns `true` and
+/// also creates a file at `./target/.slow_tests_cookie` which serves as a flag
+/// that slow tests did run.
 pub fn skip_slow_tests() -> bool {
     let should_skip = std::env::var("CI").is_err() && std::env::var("RUN_SLOW_TESTS").is_err();
     if should_skip {
@@ -367,8 +396,9 @@ pub fn skip_slow_tests() -> bool {
     should_skip
 }
 
-const REWRITE: bool = false;
-
+/// Asserts that `expected` and `actual` strings are equal. If they differ only
+/// in trailing or leading whitespace the test won't fail and
+/// the contents of `actual` will be written to the file located at `path`.
 fn assert_equal_text(expected: &str, actual: &str, path: &Path) {
     if expected == actual {
         return;
@@ -381,6 +411,7 @@ fn assert_equal_text(expected: &str, actual: &str, path: &Path) {
         fs::write(path, actual).unwrap();
         return;
     }
+    const REWRITE: bool = false;
     if REWRITE {
         println!("rewriting {}", pretty_path.display());
         fs::write(path, actual).unwrap();
diff --git a/crates/test_utils/src/marks.rs b/crates/test_utils/src/marks.rs
index fe1813947..f8fabfaff 100644
--- a/crates/test_utils/src/marks.rs
+++ b/crates/test_utils/src/marks.rs
@@ -1,4 +1,4 @@
-//! This module implements manually tracked test coverage, which useful for
+//! This module implements manually tracked test coverage, which is useful for
 //! quickly finding a test responsible for testing a particular bit of code.
 //!
 //! See <https://matklad.github.io/2018/06/18/a-trick-for-test-maintenance.html>