17 files changed, 469 insertions, 267 deletions

diff --git a/Cargo.lock b/Cargo.lock
index b890b6e19..d470d84f2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1191,9 +1191,9 @@ dependencies = [
 
 [[package]]
 name = "pulldown-cmark"
-version = "0.7.2"
+version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ca36dea94d187597e104a5c8e4b07576a8a45aa5db48a65e12940d3eb7461f55"
+checksum = "ffade02495f22453cd593159ea2f59827aae7f53fa8323f756799b670881dcf8"
 dependencies = [
  "bitflags",
  "memchr",
@@ -1202,9 +1202,9 @@ dependencies = [
 
 [[package]]
 name = "pulldown-cmark-to-cmark"
-version = "5.0.0"
+version = "6.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32accf4473121d8c0b508ca5673363703762d6cc59cf25af1df48f653346f736"
+checksum = "e8f2b9878102358ec65434fdd1a9a161f8648bb2f531acc9260e4d094c96de23"
 dependencies = [
  "pulldown-cmark",
 ]
@@ -1361,11 +1361,11 @@ checksum = "71d301d4193d031abdd79ff7e3dd721168a9572ef3fe51a1517aba235bd8f86e"
 
 [[package]]
 name = "salsa"
-version = "0.15.2"
+version = "0.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9ab29056d4fb4048a5f0d169c9b6e5526160c9ec37aded5a6879c2c9c445a8e4"
+checksum = "d8fadca2ab5de17acf66d744f4888049ca8f1bb9b8a1ab8afd9d032cc959c5dc"
 dependencies = [
- "crossbeam-utils 0.7.2",
+ "crossbeam-utils 0.8.0",
  "indexmap",
  "lock_api",
  "log",
@@ -1378,9 +1378,9 @@ dependencies = [
 
 [[package]]
 name = "salsa-macros"
-version = "0.15.2"
+version = "0.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a1c3aec007c63c4ed4cd7a018529fb0b5575c4562575fc6a40d6cd2ae0b792ef"
+checksum = "cd3904a4ba0a9d0211816177fd34b04c7095443f8cdacd11175064fe541c8fe2"
 dependencies = [
  "heck",
  "proc-macro2",
diff --git a/bors.toml b/bors.toml
index 1f4eb510a..1f6603030 100644
--- a/bors.toml
+++ b/bors.toml
@@ -6,3 +6,4 @@ status = [
     "TypeScript (windows-latest)",
 ]
 delete_merged_branches = true
+timeout_sec = 1200 # 20 min
diff --git a/crates/assists/src/handlers/auto_import.rs b/crates/assists/src/handlers/auto_import.rs
index d3ee98e5f..e595b5b93 100644
--- a/crates/assists/src/handlers/auto_import.rs
+++ b/crates/assists/src/handlers/auto_import.rs
@@ -1,21 +1,9 @@
-use std::collections::BTreeSet;
-
-use either::Either;
-use hir::{
-    AsAssocItem, AssocItemContainer, ModPath, Module, ModuleDef, PathResolution, Semantics, Trait,
-    Type,
-};
-use ide_db::{imports_locator, RootDatabase};
-use insert_use::ImportScope;
-use rustc_hash::FxHashSet;
-use syntax::{
-    ast::{self, AstNode},
-    SyntaxNode,
-};
+use syntax::ast;
 
 use crate::{
-    utils::insert_use, utils::mod_path_to_ast, AssistContext, AssistId, AssistKind, Assists,
-    GroupLabel,
+    utils::import_assets::{ImportAssets, ImportCandidate},
+    utils::{insert_use, mod_path_to_ast, ImportScope},
+    AssistContext, AssistId, AssistKind, Assists, GroupLabel,
 };
 
 // Assist: auto_import
@@ -38,16 +26,24 @@ use crate::{
 // # pub mod std { pub mod collections { pub struct HashMap { } } }
 // ```
 pub(crate) fn auto_import(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
-    let auto_import_assets = AutoImportAssets::new(ctx)?;
-    let proposed_imports = auto_import_assets.search_for_imports(ctx);
+    let import_assets =
+        if let Some(path_under_caret) = ctx.find_node_at_offset_with_descend::<ast::Path>() {
+            ImportAssets::for_regular_path(path_under_caret, &ctx.sema)
+        } else if let Some(method_under_caret) =
+            ctx.find_node_at_offset_with_descend::<ast::MethodCallExpr>()
+        {
+            ImportAssets::for_method_call(method_under_caret, &ctx.sema)
+        } else {
+            None
+        }?;
+    let proposed_imports = import_assets.search_for_imports(&ctx.sema, &ctx.config.insert_use);
     if proposed_imports.is_empty() {
         return None;
     }
 
-    let range = ctx.sema.original_range(&auto_import_assets.syntax_under_caret).range;
-    let group = auto_import_assets.get_import_group_message();
-    let scope =
-        ImportScope::find_insert_use_container(&auto_import_assets.syntax_under_caret, ctx)?;
+    let range = ctx.sema.original_range(import_assets.syntax_under_caret()).range;
+    let group = import_group_message(import_assets.import_candidate());
+    let scope = ImportScope::find_insert_use_container(import_assets.syntax_under_caret(), ctx)?;
     let syntax = scope.as_syntax_node();
     for import in proposed_imports {
         acc.add_group(
@@ -65,227 +61,18 @@ pub(crate) fn auto_import(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
     Some(())
 }
 
-#[derive(Debug)]
-struct AutoImportAssets {
-    import_candidate: ImportCandidate,
-    module_with_name_to_import: Module,
-    syntax_under_caret: SyntaxNode,
-}
-
-impl AutoImportAssets {
-    fn new(ctx: &AssistContext) -> Option<Self> {
-        if let Some(path_under_caret) = ctx.find_node_at_offset_with_descend::<ast::Path>() {
-            Self::for_regular_path(path_under_caret, &ctx)
-        } else {
-            Self::for_method_call(ctx.find_node_at_offset_with_descend()?, &ctx)
-        }
-    }
-
-    fn for_method_call(method_call: ast::MethodCallExpr, ctx: &AssistContext) -> Option<Self> {
-        let syntax_under_caret = method_call.syntax().to_owned();
-        let module_with_name_to_import = ctx.sema.scope(&syntax_under_caret).module()?;
-        Some(Self {
-            import_candidate: ImportCandidate::for_method_call(&ctx.sema, &method_call)?,
-            module_with_name_to_import,
-            syntax_under_caret,
-        })
-    }
-
-    fn for_regular_path(path_under_caret: ast::Path, ctx: &AssistContext) -> Option<Self> {
-        let syntax_under_caret = path_under_caret.syntax().to_owned();
-        if syntax_under_caret.ancestors().find_map(ast::Use::cast).is_some() {
-            return None;
-        }
-
-        let module_with_name_to_import = ctx.sema.scope(&syntax_under_caret).module()?;
-        Some(Self {
-            import_candidate: ImportCandidate::for_regular_path(&ctx.sema, &path_under_caret)?,
-            module_with_name_to_import,
-            syntax_under_caret,
-        })
-    }
-
-    fn get_search_query(&self) -> &str {
-        match &self.import_candidate {
-            ImportCandidate::UnqualifiedName(name) => name,
-            ImportCandidate::QualifierStart(qualifier_start) => qualifier_start,
-            ImportCandidate::TraitAssocItem(_, trait_assoc_item_name) => trait_assoc_item_name,
-            ImportCandidate::TraitMethod(_, trait_method_name) => trait_method_name,
-        }
-    }
-
-    fn get_import_group_message(&self) -> GroupLabel {
-        let name = match &self.import_candidate {
-            ImportCandidate::UnqualifiedName(name) => format!("Import {}", name),
-            ImportCandidate::QualifierStart(qualifier_start) => {
-                format!("Import {}", qualifier_start)
-            }
-            ImportCandidate::TraitAssocItem(_, trait_assoc_item_name) => {
-                format!("Import a trait for item {}", trait_assoc_item_name)
-            }
-            ImportCandidate::TraitMethod(_, trait_method_name) => {
-                format!("Import a trait for method {}", trait_method_name)
-            }
-        };
-        GroupLabel(name)
-    }
-
-    fn search_for_imports(&self, ctx: &AssistContext) -> BTreeSet<ModPath> {
-        let _p = profile::span("auto_import::search_for_imports");
-        let db = ctx.db();
-        let current_crate = self.module_with_name_to_import.krate();
-        imports_locator::find_imports(&ctx.sema, current_crate, &self.get_search_query())
-            .into_iter()
-            .filter_map(|candidate| match &self.import_candidate {
-                ImportCandidate::TraitAssocItem(assoc_item_type, _) => {
-                    let located_assoc_item = match candidate {
-                        Either::Left(ModuleDef::Function(located_function)) => located_function
-                            .as_assoc_item(db)
-                            .map(|assoc| assoc.container(db))
-                            .and_then(Self::assoc_to_trait),
-                        Either::Left(ModuleDef::Const(located_const)) => located_const
-                            .as_assoc_item(db)
-                            .map(|assoc| assoc.container(db))
-                            .and_then(Self::assoc_to_trait),
-                        _ => None,
-                    }?;
-
-                    let mut trait_candidates = FxHashSet::default();
-                    trait_candidates.insert(located_assoc_item.into());
-
-                    assoc_item_type
-                        .iterate_path_candidates(
-                            db,
-                            current_crate,
-                            &trait_candidates,
-                            None,
-                            |_, assoc| Self::assoc_to_trait(assoc.container(db)),
-                        )
-                        .map(ModuleDef::from)
-                        .map(Either::Left)
-                }
-                ImportCandidate::TraitMethod(function_callee, _) => {
-                    let located_assoc_item =
-                        if let Either::Left(ModuleDef::Function(located_function)) = candidate {
-                            located_function
-                                .as_assoc_item(db)
-                                .map(|assoc| assoc.container(db))
-                                .and_then(Self::assoc_to_trait)
-                        } else {
-                            None
-                        }?;
-
-                    let mut trait_candidates = FxHashSet::default();
-                    trait_candidates.insert(located_assoc_item.into());
-
-                    function_callee
-                        .iterate_method_candidates(
-                            db,
-                            current_crate,
-                            &trait_candidates,
-                            None,
-                            |_, function| {
-                                Self::assoc_to_trait(function.as_assoc_item(db)?.container(db))
-                            },
-                        )
-                        .map(ModuleDef::from)
-                        .map(Either::Left)
-                }
-                _ => Some(candidate),
-            })
-            .filter_map(|candidate| match candidate {
-                Either::Left(module_def) => self.module_with_name_to_import.find_use_path_prefixed(
-                    db,
-                    module_def,
-                    ctx.config.insert_use.prefix_kind,
-                ),
-                Either::Right(macro_def) => self.module_with_name_to_import.find_use_path_prefixed(
-                    db,
-                    macro_def,
-                    ctx.config.insert_use.prefix_kind,
-                ),
-            })
-            .filter(|use_path| !use_path.segments.is_empty())
-            .take(20)
-            .collect::<BTreeSet<_>>()
-    }
-
-    fn assoc_to_trait(assoc: AssocItemContainer) -> Option<Trait> {
-        if let AssocItemContainer::Trait(extracted_trait) = assoc {
-            Some(extracted_trait)
-        } else {
-            None
-        }
-    }
-}
-
-#[derive(Debug)]
-enum ImportCandidate {
-    /// Simple name like 'HashMap'
-    UnqualifiedName(String),
-    /// First part of the qualified name.
-    /// For 'std::collections::HashMap', that will be 'std'.
-    QualifierStart(String),
-    /// A trait associated function (with no self parameter) or associated constant.
-    /// For 'test_mod::TestEnum::test_function', `Type` is the `test_mod::TestEnum` expression type
-    /// and `String` is the `test_function`
-    TraitAssocItem(Type, String),
-    /// A trait method with self parameter.
-    /// For 'test_enum.test_method()', `Type` is the `test_enum` expression type
-    /// and `String` is the `test_method`
-    TraitMethod(Type, String),
-}
-
-impl ImportCandidate {
-    fn for_method_call(
-        sema: &Semantics<RootDatabase>,
-        method_call: &ast::MethodCallExpr,
-    ) -> Option<Self> {
-        if sema.resolve_method_call(method_call).is_some() {
-            return None;
-        }
-        Some(Self::TraitMethod(
-            sema.type_of_expr(&method_call.receiver()?)?,
-            method_call.name_ref()?.syntax().to_string(),
-        ))
-    }
-
-    fn for_regular_path(
-        sema: &Semantics<RootDatabase>,
-        path_under_caret: &ast::Path,
-    ) -> Option<Self> {
-        if sema.resolve_path(path_under_caret).is_some() {
-            return None;
+fn import_group_message(import_candidate: &ImportCandidate) -> GroupLabel {
+    let name = match import_candidate {
+        ImportCandidate::UnqualifiedName(candidate)
+        | ImportCandidate::QualifierStart(candidate) => format!("Import {}", &candidate.name),
+        ImportCandidate::TraitAssocItem(candidate) => {
+            format!("Import a trait for item {}", &candidate.name)
         }
-
-        let segment = path_under_caret.segment()?;
-        if let Some(qualifier) = path_under_caret.qualifier() {
-            let qualifier_start = qualifier.syntax().descendants().find_map(ast::NameRef::cast)?;
-            let qualifier_start_path =
-                qualifier_start.syntax().ancestors().find_map(ast::Path::cast)?;
-            if let Some(qualifier_start_resolution) = sema.resolve_path(&qualifier_start_path) {
-                let qualifier_resolution = if qualifier_start_path == qualifier {
-                    qualifier_start_resolution
-                } else {
-                    sema.resolve_path(&qualifier)?
-                };
-                if let PathResolution::Def(ModuleDef::Adt(assoc_item_path)) = qualifier_resolution {
-                    Some(ImportCandidate::TraitAssocItem(
-                        assoc_item_path.ty(sema.db),
-                        segment.syntax().to_string(),
-                    ))
-                } else {
-                    None
-                }
-            } else {
-                Some(ImportCandidate::QualifierStart(qualifier_start.syntax().to_string()))
-            }
-        } else {
-            Some(ImportCandidate::UnqualifiedName(
-                segment.syntax().descendants().find_map(ast::NameRef::cast)?.syntax().to_string(),
-            ))
+        ImportCandidate::TraitMethod(candidate) => {
+            format!("Import a trait for method {}", &candidate.name)
         }
-    }
+    };
+    GroupLabel(name)
 }
 
 #[cfg(test)]
diff --git a/crates/assists/src/handlers/merge_imports.rs b/crates/assists/src/handlers/merge_imports.rs
index fe33cee53..fd9c9e03c 100644
--- a/crates/assists/src/handlers/merge_imports.rs
+++ b/crates/assists/src/handlers/merge_imports.rs
@@ -73,6 +73,20 @@ mod tests {
     use super::*;
 
     #[test]
+    fn test_merge_equal() {
+        check_assist(
+            merge_imports,
+            r"
+use std::fmt<|>::{Display, Debug};
+use std::fmt::{Display, Debug};
+",
+            r"
+use std::fmt::{Debug, Display};
+",
+        )
+    }
+
+    #[test]
     fn test_merge_first() {
         check_assist(
             merge_imports,
diff --git a/crates/assists/src/handlers/replace_qualified_name_with_use.rs b/crates/assists/src/handlers/replace_qualified_name_with_use.rs
index e95b971a4..c50bc7604 100644
--- a/crates/assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/assists/src/handlers/replace_qualified_name_with_use.rs
@@ -124,6 +124,23 @@ mod tests {
     use super::*;
 
     #[test]
+    fn test_replace_already_imported() {
+        check_assist(
+            replace_qualified_name_with_use,
+            r"use std::fs;
+
+fn main() {
+    std::f<|>s::Path
+}",
+            r"use std::fs;
+
+fn main() {
+    fs::Path
+}",
+        )
+    }
+
+    #[test]
     fn test_replace_add_use_no_anchor() {
         check_assist(
             replace_qualified_name_with_use,
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index c1847f601..b37b0d2b6 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -1,5 +1,6 @@
 //! Assorted functions shared by several assists.
 pub(crate) mod insert_use;
+pub(crate) mod import_assets;
 
 use std::{iter, ops};
 
diff --git a/crates/assists/src/utils/import_assets.rs b/crates/assists/src/utils/import_assets.rs
new file mode 100644
index 000000000..601f51098
--- /dev/null
+++ b/crates/assists/src/utils/import_assets.rs
@@ -0,0 +1,268 @@
+//! Look up accessible paths for items.
+use std::collections::BTreeSet;
+
+use either::Either;
+use hir::{AsAssocItem, AssocItemContainer, ModuleDef, Semantics};
+use ide_db::{imports_locator, RootDatabase};
+use rustc_hash::FxHashSet;
+use syntax::{ast, AstNode, SyntaxNode};
+
+use crate::assist_config::InsertUseConfig;
+
+#[derive(Debug)]
+pub(crate) enum ImportCandidate {
+    /// Simple name like 'HashMap'
+    UnqualifiedName(PathImportCandidate),
+    /// First part of the qualified name.
+    /// For 'std::collections::HashMap', that will be 'std'.
+    QualifierStart(PathImportCandidate),
+    /// A trait associated function (with no self parameter) or associated constant.
+    /// For 'test_mod::TestEnum::test_function', `ty` is the `test_mod::TestEnum` expression type
+    /// and `name` is the `test_function`
+    TraitAssocItem(TraitImportCandidate),
+    /// A trait method with self parameter.
+    /// For 'test_enum.test_method()', `ty` is the `test_enum` expression type
+    /// and `name` is the `test_method`
+    TraitMethod(TraitImportCandidate),
+}
+
+#[derive(Debug)]
+pub(crate) struct TraitImportCandidate {
+    pub ty: hir::Type,
+    pub name: String,
+}
+
+#[derive(Debug)]
+pub(crate) struct PathImportCandidate {
+    pub name: String,
+}
+
+#[derive(Debug)]
+pub(crate) struct ImportAssets {
+    import_candidate: ImportCandidate,
+    module_with_name_to_import: hir::Module,
+    syntax_under_caret: SyntaxNode,
+}
+
+impl ImportAssets {
+    pub(crate) fn for_method_call(
+        method_call: ast::MethodCallExpr,
+        sema: &Semantics<RootDatabase>,
+    ) -> Option<Self> {
+        let syntax_under_caret = method_call.syntax().to_owned();
+        let module_with_name_to_import = sema.scope(&syntax_under_caret).module()?;
+        Some(Self {
+            import_candidate: ImportCandidate::for_method_call(sema, &method_call)?,
+            module_with_name_to_import,
+            syntax_under_caret,
+        })
+    }
+
+    pub(crate) fn for_regular_path(
+        path_under_caret: ast::Path,
+        sema: &Semantics<RootDatabase>,
+    ) -> Option<Self> {
+        let syntax_under_caret = path_under_caret.syntax().to_owned();
+        if syntax_under_caret.ancestors().find_map(ast::Use::cast).is_some() {
+            return None;
+        }
+
+        let module_with_name_to_import = sema.scope(&syntax_under_caret).module()?;
+        Some(Self {
+            import_candidate: ImportCandidate::for_regular_path(sema, &path_under_caret)?,
+            module_with_name_to_import,
+            syntax_under_caret,
+        })
+    }
+
+    pub(crate) fn syntax_under_caret(&self) -> &SyntaxNode {
+        &self.syntax_under_caret
+    }
+
+    pub(crate) fn import_candidate(&self) -> &ImportCandidate {
+        &self.import_candidate
+    }
+
+    fn get_search_query(&self) -> &str {
+        match &self.import_candidate {
+            ImportCandidate::UnqualifiedName(candidate)
+            | ImportCandidate::QualifierStart(candidate) => &candidate.name,
+            ImportCandidate::TraitAssocItem(candidate)
+            | ImportCandidate::TraitMethod(candidate) => &candidate.name,
+        }
+    }
+
+    pub(crate) fn search_for_imports(
+        &self,
+        sema: &Semantics<RootDatabase>,
+        config: &InsertUseConfig,
+    ) -> BTreeSet<hir::ModPath> {
+        let _p = profile::span("import_assists::search_for_imports");
+        self.search_for(sema, Some(config.prefix_kind))
+    }
+
+    /// This may return non-absolute paths if a part of the returned path is already imported into scope.
+    #[allow(dead_code)]
+    pub(crate) fn search_for_relative_paths(
+        &self,
+        sema: &Semantics<RootDatabase>,
+    ) -> BTreeSet<hir::ModPath> {
+        let _p = profile::span("import_assists::search_for_relative_paths");
+        self.search_for(sema, None)
+    }
+
+    fn search_for(
+        &self,
+        sema: &Semantics<RootDatabase>,
+        prefixed: Option<hir::PrefixKind>,
+    ) -> BTreeSet<hir::ModPath> {
+        let db = sema.db;
+        let mut trait_candidates = FxHashSet::default();
+        let current_crate = self.module_with_name_to_import.krate();
+
+        let filter = |candidate: Either<hir::ModuleDef, hir::MacroDef>| {
+            trait_candidates.clear();
+            match &self.import_candidate {
+                ImportCandidate::TraitAssocItem(trait_candidate) => {
+                    let located_assoc_item = match candidate {
+                        Either::Left(ModuleDef::Function(located_function)) => {
+                            located_function.as_assoc_item(db)
+                        }
+                        Either::Left(ModuleDef::Const(located_const)) => {
+                            located_const.as_assoc_item(db)
+                        }
+                        _ => None,
+                    }
+                    .map(|assoc| assoc.container(db))
+                    .and_then(Self::assoc_to_trait)?;
+
+                    trait_candidates.insert(located_assoc_item.into());
+
+                    trait_candidate
+                        .ty
+                        .iterate_path_candidates(
+                            db,
+                            current_crate,
+                            &trait_candidates,
+                            None,
+                            |_, assoc| Self::assoc_to_trait(assoc.container(db)),
+                        )
+                        .map(ModuleDef::from)
+                        .map(Either::Left)
+                }
+                ImportCandidate::TraitMethod(trait_candidate) => {
+                    let located_assoc_item =
+                        if let Either::Left(ModuleDef::Function(located_function)) = candidate {
+                            located_function
+                                .as_assoc_item(db)
+                                .map(|assoc| assoc.container(db))
+                                .and_then(Self::assoc_to_trait)
+                        } else {
+                            None
+                        }?;
+
+                    trait_candidates.insert(located_assoc_item.into());
+
+                    trait_candidate
+                        .ty
+                        .iterate_method_candidates(
+                            db,
+                            current_crate,
+                            &trait_candidates,
+                            None,
+                            |_, function| {
+                                Self::assoc_to_trait(function.as_assoc_item(db)?.container(db))
+                            },
+                        )
+                        .map(ModuleDef::from)
+                        .map(Either::Left)
+                }
+                _ => Some(candidate),
+            }
+        };
+
+        imports_locator::find_imports(sema, current_crate, &self.get_search_query())
+            .into_iter()
+            .filter_map(filter)
+            .filter_map(|candidate| {
+                let item: hir::ItemInNs = candidate.either(Into::into, Into::into);
+                if let Some(prefix_kind) = prefixed {
+                    self.module_with_name_to_import.find_use_path_prefixed(db, item, prefix_kind)
+                } else {
+                    self.module_with_name_to_import.find_use_path(db, item)
+                }
+            })
+            .filter(|use_path| !use_path.segments.is_empty())
+            .take(20)
+            .collect::<BTreeSet<_>>()
+    }
+
+    fn assoc_to_trait(assoc: AssocItemContainer) -> Option<hir::Trait> {
+        if let AssocItemContainer::Trait(extracted_trait) = assoc {
+            Some(extracted_trait)
+        } else {
+            None
+        }
+    }
+}
+
+impl ImportCandidate {
+    fn for_method_call(
+        sema: &Semantics<RootDatabase>,
+        method_call: &ast::MethodCallExpr,
+    ) -> Option<Self> {
+        match sema.resolve_method_call(method_call) {
+            Some(_) => None,
+            None => Some(Self::TraitMethod(TraitImportCandidate {
+                ty: sema.type_of_expr(&method_call.receiver()?)?,
+                name: method_call.name_ref()?.syntax().to_string(),
+            })),
+        }
+    }
+
+    fn for_regular_path(
+        sema: &Semantics<RootDatabase>,
+        path_under_caret: &ast::Path,
+    ) -> Option<Self> {
+        if sema.resolve_path(path_under_caret).is_some() {
+            return None;
+        }
+
+        let segment = path_under_caret.segment()?;
+        let candidate = if let Some(qualifier) = path_under_caret.qualifier() {
+            let qualifier_start = qualifier.syntax().descendants().find_map(ast::NameRef::cast)?;
+            let qualifier_start_path =
+                qualifier_start.syntax().ancestors().find_map(ast::Path::cast)?;
+            if let Some(qualifier_start_resolution) = sema.resolve_path(&qualifier_start_path) {
+                let qualifier_resolution = if qualifier_start_path == qualifier {
+                    qualifier_start_resolution
+                } else {
+                    sema.resolve_path(&qualifier)?
+                };
+                match qualifier_resolution {
+                    hir::PathResolution::Def(hir::ModuleDef::Adt(assoc_item_path)) => {
+                        ImportCandidate::TraitAssocItem(TraitImportCandidate {
+                            ty: assoc_item_path.ty(sema.db),
+                            name: segment.syntax().to_string(),
+                        })
+                    }
+                    _ => return None,
+                }
+            } else {
+                ImportCandidate::QualifierStart(PathImportCandidate {
+                    name: qualifier_start.syntax().to_string(),
+                })
+            }
+        } else {
+            ImportCandidate::UnqualifiedName(PathImportCandidate {
+                name: segment
+                    .syntax()
+                    .descendants()
+                    .find_map(ast::NameRef::cast)?
+                    .syntax()
+                    .to_string(),
+            })
+        };
+        Some(candidate)
+    }
+}
diff --git a/crates/assists/src/utils/insert_use.rs b/crates/assists/src/utils/insert_use.rs
index bfd457d18..409985b3b 100644
--- a/crates/assists/src/utils/insert_use.rs
+++ b/crates/assists/src/utils/insert_use.rs
@@ -173,8 +173,15 @@ pub(crate) fn try_merge_trees(
     let rhs_path = rhs.path()?;
 
     let (lhs_prefix, rhs_prefix) = common_prefix(&lhs_path, &rhs_path)?;
-    let lhs = lhs.split_prefix(&lhs_prefix);
-    let rhs = rhs.split_prefix(&rhs_prefix);
+    let (lhs, rhs) = if is_simple_path(lhs)
+        && is_simple_path(rhs)
+        && lhs_path == lhs_prefix
+        && rhs_path == rhs_prefix
+    {
+        (lhs.clone(), rhs.clone())
+    } else {
+        (lhs.split_prefix(&lhs_prefix), rhs.split_prefix(&rhs_prefix))
+    };
     recursive_merge(&lhs, &rhs, merge)
 }
 
@@ -250,6 +257,10 @@ fn recursive_merge(
                         use_trees.insert(idx, make::glob_use_tree());
                         continue;
                     }
+
+                    if lhs_t.use_tree_list().is_none() && rhs_t.use_tree_list().is_none() {
+                        continue;
+                    }
                 }
                 let lhs = lhs_t.split_prefix(&lhs_prefix);
                 let rhs = rhs_t.split_prefix(&rhs_prefix);
@@ -295,6 +306,10 @@ fn common_prefix(lhs: &ast::Path, rhs: &ast::Path) -> Option<(ast::Path, ast::Pa
     }
 }
 
+fn is_simple_path(use_tree: &ast::UseTree) -> bool {
+    use_tree.use_tree_list().is_none() && use_tree.star_token().is_none()
+}
+
 fn path_is_self(path: &ast::Path) -> bool {
     path.segment().and_then(|seg| seg.self_token()).is_some() && path.qualifier().is_none()
 }
@@ -524,6 +539,11 @@ mod tests {
     use test_utils::assert_eq_text;
 
     #[test]
+    fn insert_existing() {
+        check_full("std::fs", "use std::fs;", "use std::fs;")
+    }
+
+    #[test]
     fn insert_start() {
         check_none(
             "std::bar::AA",
diff --git a/crates/base_db/Cargo.toml b/crates/base_db/Cargo.toml
index f7bfcb0d7..1724d2f85 100644
--- a/crates/base_db/Cargo.toml
+++ b/crates/base_db/Cargo.toml
@@ -10,7 +10,7 @@ edition = "2018"
 doctest = false
 
 [dependencies]
-salsa = "0.15.2"
+salsa = "0.16.0"
 rustc-hash = "1.1.0"
 
 syntax = { path = "../syntax", version = "0.0.0" }
diff --git a/crates/ide/Cargo.toml b/crates/ide/Cargo.toml
index f0257403d..29dc9a6a8 100644
--- a/crates/ide/Cargo.toml
+++ b/crates/ide/Cargo.toml
@@ -16,8 +16,8 @@ itertools = "0.9.0"
 log = "0.4.8"
 rustc-hash = "1.1.0"
 oorandom = "11.1.2"
-pulldown-cmark-to-cmark = "5.0.0"
-pulldown-cmark = {version = "0.7.2", default-features = false}
+pulldown-cmark-to-cmark = "6.0.0"
+pulldown-cmark = { version = "0.8.0", default-features = false }
 url = "2.1.1"
 
 stdx = { path = "../stdx", version = "0.0.0" }
diff --git a/crates/ide/src/completion.rs b/crates/ide/src/completion.rs
index 697f691b0..b0e35b2bd 100644
--- a/crates/ide/src/completion.rs
+++ b/crates/ide/src/completion.rs
@@ -61,6 +61,8 @@ pub use crate::completion::{
 // - `expr.refm` -> `&mut expr`
 // - `expr.not` -> `!expr`
 // - `expr.dbg` -> `dbg!(expr)`
+// - `expr.dbgr` -> `dbg!(&expr)`
+// - `expr.call` -> `(expr)`
 //
 // There also snippet completions:
 //
diff --git a/crates/ide/src/doc_links.rs b/crates/ide/src/doc_links.rs
index 06af36b73..db3f911c8 100644
--- a/crates/ide/src/doc_links.rs
+++ b/crates/ide/src/doc_links.rs
@@ -1,9 +1,10 @@
 //! Resolves and rewrites links in markdown documentation.
 
+use std::convert::TryFrom;
 use std::iter::once;
 
 use itertools::Itertools;
-use pulldown_cmark::{CowStr, Event, LinkType, Options, Parser, Tag};
+use pulldown_cmark::{BrokenLink, CowStr, Event, InlineStr, LinkType, Options, Parser, Tag};
 use pulldown_cmark_to_cmark::{cmark_with_options, Options as CmarkOptions};
 use url::Url;
 
@@ -24,11 +25,13 @@ pub type DocumentationLink = String;
 
 /// Rewrite documentation links in markdown to point to an online host (e.g. docs.rs)
 pub fn rewrite_links(db: &RootDatabase, markdown: &str, definition: &Definition) -> String {
-    let doc = Parser::new_with_broken_link_callback(
-        markdown,
-        Options::empty(),
-        Some(&|label, _| Some((/*url*/ label.to_string(), /*title*/ label.to_string()))),
-    );
+    let mut cb = |link: BrokenLink| {
+        Some((
+            /*url*/ link.reference.to_owned().into(),
+            /*title*/ link.reference.to_owned().into(),
+        ))
+    };
+    let doc = Parser::new_with_broken_link_callback(markdown, Options::empty(), Some(&mut cb));
 
     let doc = map_links(doc, |target, title: &str| {
         // This check is imperfect, there's some overlap between valid intra-doc links
@@ -66,11 +69,11 @@ pub fn remove_links(markdown: &str) -> String {
     let mut opts = Options::empty();
     opts.insert(Options::ENABLE_FOOTNOTES);
 
-    let doc = Parser::new_with_broken_link_callback(
-        markdown,
-        opts,
-        Some(&|_, _| Some((String::new(), String::new()))),
-    );
+    let mut cb = |_: BrokenLink| {
+        let empty = InlineStr::try_from("").unwrap();
+        Some((CowStr::Inlined(empty.clone()), CowStr::Inlined(empty)))
+    };
+    let doc = Parser::new_with_broken_link_callback(markdown, opts, Some(&mut cb));
     let doc = doc.filter_map(move |evt| match evt {
         Event::Start(Tag::Link(link_type, ref target, ref title)) => {
             if link_type == LinkType::Inline && target.contains("://") {
diff --git a/crates/project_model/src/sysroot.rs b/crates/project_model/src/sysroot.rs
index e529e07b0..b2ff98a15 100644
--- a/crates/project_model/src/sysroot.rs
+++ b/crates/project_model/src/sysroot.rs
@@ -49,6 +49,7 @@ impl Sysroot {
     }
 
     pub fn discover(cargo_toml: &AbsPath) -> Result<Sysroot> {
+        log::debug!("Discovering sysroot for {}", cargo_toml.display());
         let current_dir = cargo_toml.parent().unwrap();
         let sysroot_src_dir = discover_sysroot_src_dir(current_dir)?;
         let res = Sysroot::load(&sysroot_src_dir)?;
@@ -115,12 +116,14 @@ fn discover_sysroot_src_dir(current_dir: &AbsPath) -> Result<AbsPathBuf> {
     if let Ok(path) = env::var("RUST_SRC_PATH") {
         let path = AbsPathBuf::try_from(path.as_str())
             .map_err(|path| format_err!("RUST_SRC_PATH must be absolute: {}", path.display()))?;
+        log::debug!("Discovered sysroot by RUST_SRC_PATH: {}", path.display());
         return Ok(path);
     }
 
     let sysroot_path = {
         let mut rustc = Command::new(toolchain::rustc());
         rustc.current_dir(current_dir).args(&["--print", "sysroot"]);
+        log::debug!("Discovering sysroot by {:?}", rustc);
         let stdout = utf8_stdout(rustc)?;
         AbsPathBuf::assert(PathBuf::from(stdout))
     };
@@ -150,6 +153,7 @@ fn get_rust_src(sysroot_path: &AbsPath) -> Option<AbsPathBuf> {
     // FIXME: remove `src` when 1.47 comes out
     // https://github.com/rust-lang/rust/pull/73265
     let rust_src = sysroot_path.join("lib/rustlib/src/rust");
+    log::debug!("Checking sysroot (looking for `library` and `src` dirs): {}", rust_src.display());
     ["library", "src"].iter().map(|it| rust_src.join(it)).find(|it| it.exists())
 }
 
diff --git a/docs/dev/README.md b/docs/dev/README.md
index 36edddc70..90e74f226 100644
--- a/docs/dev/README.md
+++ b/docs/dev/README.md
@@ -35,7 +35,12 @@ https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0
 * [E-easy](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy),
   [E-medium](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AE-medium),
   [E-hard](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AE-hard),
-  labels are *estimates* for how hard would be to write a fix.
+  [E-unknown](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AE-unknown),
+  labels are *estimates* for how hard would be to write a fix. Each triaged issue should have one of these labels.
+* [S-actionable](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AS-actionable) and
+  [S-unactionable](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AS-unactionable)
+  specify if there are concrete steps to resolve or advance an issue. Roughly, actionable issues need only work to be fixed,
+  while unactionable ones are effectively wont-fix. Each triaged issue should have one of these labels.
 * [fun](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3Afun)
   is for cool, but probably hard stuff.
 
diff --git a/docs/dev/lsp-extensions.md b/docs/dev/lsp-extensions.md
index 3f861f3e0..43a69d6ce 100644
--- a/docs/dev/lsp-extensions.md
+++ b/docs/dev/lsp-extensions.md
@@ -1,3 +1,13 @@
+<!---
+lsp_ext.rs hash: 286f8bbac885531a
+
+If you need to change the above hash to make the test pass, please check if you
+need to adjust this doc as well and ping this issue:
+
+  https://github.com/rust-analyzer/rust-analyzer/issues/4604
+
+--->
+
 # LSP Extensions
 
 This document describes LSP extensions used by rust-analyzer.
diff --git a/docs/dev/style.md b/docs/dev/style.md
index 59067d234..435de63e3 100644
--- a/docs/dev/style.md
+++ b/docs/dev/style.md
@@ -186,6 +186,31 @@ impl Person {
 }
 ```
 
+## Constructors
+
+Prefer `Default` to zero-argument `new` function
+
+```rust
+// Good
+#[derive(Default)]
+struct Foo {
+    bar: Option<Bar>
+}
+
+// Not as good
+struct Foo {
+    bar: Option<Bar>
+}
+
+impl Foo {
+    fn new() -> Foo {
+        Foo { bar: None }
+    }
+}
+```
+
+Prefer `Default` even it has to be implemented manually.
+
 ## Avoid Monomorphization
 
 Rust uses monomorphization to compile generic code, meaning that for each instantiation of a generic functions with concrete types, the function is compiled afresh, *per crate*.
diff --git a/xtask/tests/tidy.rs b/xtask/tests/tidy.rs
index 0c233f87d..b3bb9d543 100644
--- a/xtask/tests/tidy.rs
+++ b/xtask/tests/tidy.rs
@@ -45,6 +45,41 @@ fn smoke_test_docs_generation() {
 }
 
 #[test]
+fn check_lsp_extensions_docs() {
+    let expected_hash = {
+        let lsp_ext_rs =
+            fs2::read_to_string(project_root().join("crates/rust-analyzer/src/lsp_ext.rs"))
+                .unwrap();
+        stable_hash(lsp_ext_rs.as_str())
+    };
+
+    let actual_hash = {
+        let lsp_extensions_md =
+            fs2::read_to_string(project_root().join("docs/dev/lsp-extensions.md")).unwrap();
+        let text = lsp_extensions_md
+            .lines()
+            .find_map(|line| line.strip_prefix("lsp_ext.rs hash:"))
+            .unwrap()
+            .trim();
+        u64::from_str_radix(text, 16).unwrap()
+    };
+
+    if actual_hash != expected_hash {
+        panic!(
+            "
+lsp_ext.rs was changed without touching lsp-extensions.md.
+
+Expected hash: {:x}
+Actual hash:   {:x}
+
+Please adjust docs/dev/lsp-extensions.md.
+",
+            expected_hash, actual_hash
+        )
+    }
+}
+
+#[test]
 fn rust_files_are_tidy() {
     let mut tidy_docs = TidyDocs::default();
     for path in rust_files(&project_root().join("crates")) {
@@ -280,3 +315,13 @@ fn is_exclude_dir(p: &Path, dirs_to_exclude: &[&str]) -> bool {
         .filter_map(|it| it.as_os_str().to_str())
         .any(|it| dirs_to_exclude.contains(&it))
 }
+
+#[allow(deprecated)]
+fn stable_hash(text: &str) -> u64 {
+    use std::hash::{Hash, Hasher, SipHasher};
+
+    let text = text.replace('\r', "");
+    let mut hasher = SipHasher::default();
+    text.hash(&mut hasher);
+    hasher.finish()
+}