45 files changed, 1323 insertions, 198 deletions

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 9c81dd97e..2605bc6ae 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -12,6 +12,7 @@ jobs:
     name: Rust
     runs-on: ${{ matrix.os }}
     strategy:
+      fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
     env:
diff --git a/Cargo.lock b/Cargo.lock
index 67822cb8a..c51bc26a6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -88,7 +88,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "bstr"
-version = "0.2.9"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "memchr 2.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -115,7 +115,7 @@ dependencies = [
  "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -133,9 +133,9 @@ name = "chalk-derive"
 version = "0.1.0"
 source = "git+https://github.com/rust-lang/chalk.git?rev=ff65b5ac9860f3c36bd892c865ab23d5ff0bbae5#ff65b5ac9860f3c36bd892c865ab23d5ff0bbae5"
 dependencies = [
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -214,7 +214,7 @@ dependencies = [
 
 [[package]]
 name = "console"
-version = "0.9.1"
+version = "0.9.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "clicolors-control 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -326,7 +326,6 @@ name = "env_logger"
 version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "humantime 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -421,7 +420,7 @@ version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "aho-corasick 0.7.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "bstr 0.2.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bstr 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -444,21 +443,13 @@ dependencies = [
 ]
 
 [[package]]
-name = "humantime"
-version = "1.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "quick-error 1.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
 name = "idna"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "matches 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-bidi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "unicode-normalization 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-normalization 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -489,14 +480,14 @@ dependencies = [
 
 [[package]]
 name = "insta"
-version = "0.12.0"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "console 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "console 0.9.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "difference 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_yaml 0.8.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "uuid 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -519,7 +510,7 @@ dependencies = [
 
 [[package]]
 name = "itoa"
-version = "0.4.4"
+version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -619,18 +610,18 @@ dependencies = [
  "crossbeam-channel 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "lsp-types"
-version = "0.69.0"
+version = "0.70.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "base64 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_repr 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "url 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -739,7 +730,7 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.3.0"
+version = "1.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -784,9 +775,9 @@ version = "0.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro-hack 0.5.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -818,14 +809,14 @@ name = "proc-macro-hack"
 version = "0.5.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.7"
+version = "1.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -833,7 +824,7 @@ dependencies = [
 
 [[package]]
 name = "proptest"
-version = "0.9.4"
+version = "0.9.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bit-set 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -858,7 +849,7 @@ name = "quote"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -902,12 +893,12 @@ version = "0.1.0"
 dependencies = [
  "cargo_metadata 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "crossbeam-channel 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "insta 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "insta 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "jod-thread 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "lsp-types 0.69.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lsp-types 0.70.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -979,9 +970,9 @@ dependencies = [
  "anymap 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "drop_bomb 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "either 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "insta 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "insta 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "once_cell 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "once_cell 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_arena 0.1.0",
  "ra_cfg 0.1.0",
  "ra_db 0.1.0",
@@ -1018,7 +1009,7 @@ dependencies = [
  "chalk-rust-ir 0.1.0 (git+https://github.com/rust-lang/chalk.git?rev=ff65b5ac9860f3c36bd892c865ab23d5ff0bbae5)",
  "chalk-solve 0.1.0 (git+https://github.com/rust-lang/chalk.git?rev=ff65b5ac9860f3c36bd892c865ab23d5ff0bbae5)",
  "ena 0.13.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "insta 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "insta 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lalrpop-intern 0.15.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_arena 0.1.0",
@@ -1039,12 +1030,12 @@ dependencies = [
  "format-buf 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "fst 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "indexmap 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "insta 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "insta 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "join_to_string 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "once_cell 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "proptest 0.9.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "once_cell 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proptest 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_assists 0.1.0",
  "ra_cfg 0.1.0",
  "ra_db 0.1.0",
@@ -1071,7 +1062,7 @@ dependencies = [
  "jod-thread 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "lsp-server 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "lsp-types 0.69.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lsp-types 0.70.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_cargo_watch 0.1.0",
  "ra_ide 0.1.0",
@@ -1084,10 +1075,11 @@ dependencies = [
  "relative-path 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
  "tempfile 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
  "threadpool 1.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1118,7 +1110,7 @@ dependencies = [
  "itertools 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "jemalloc-ctl 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "jemallocator 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "once_cell 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "once_cell 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1132,7 +1124,7 @@ dependencies = [
  "ra_db 0.1.0",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1141,7 +1133,7 @@ version = "0.1.0"
 dependencies = [
  "arrayvec 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "once_cell 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "once_cell 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_parser 0.1.0",
  "ra_text_edit 0.1.0",
  "rowan 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1157,7 +1149,7 @@ dependencies = [
 name = "ra_text_edit"
 version = "0.1.0"
 dependencies = [
- "proptest 0.9.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proptest 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
  "text_unit 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1464,9 +1456,9 @@ version = "0.14.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1509,17 +1501,17 @@ name = "serde_derive"
 version = "1.0.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "serde_json"
-version = "1.0.44"
+version = "1.0.45"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "itoa 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "itoa 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "ryu 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1529,9 +1521,9 @@ name = "serde_repr"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1570,10 +1562,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "syn"
-version = "1.0.13"
+version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1604,7 +1596,7 @@ name = "test_utils"
 version = "0.1.0"
 dependencies = [
  "difference 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
  "text_unit 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1652,7 +1644,7 @@ dependencies = [
 
 [[package]]
 name = "unicode-normalization"
-version = "0.1.11"
+version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "smallvec 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1760,7 +1752,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow 1.0.26 (registry+https://github.com/rust-lang/crates.io-index)",
  "pico-args 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1787,7 +1779,7 @@ dependencies = [
 "checksum bit-set 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e84c238982c4b1e1ee668d136c510c67a13465279c0cb367ea6baf6310620a80"
 "checksum bit-vec 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "f59bbe95d4e52a6398ec21238d31577f2b28a9d86807f06ca59d191d8440d0bb"
 "checksum bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
-"checksum bstr 0.2.9 (registry+https://github.com/rust-lang/crates.io-index)" = "3ede750122d9d1f87919570cb2cccee38c84fbc8c5599b25c289af40625b7030"
+"checksum bstr 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)" = "fe8a65814ca90dfc9705af76bb6ba3c6e2534489a72270e797e603783bb4990b"
 "checksum byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "a7c3dd8985a7111efc5c80b44e23ecdd8c007de8ade3b96595387e812b957cf5"
 "checksum c2-chacha 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "214238caa1bf3a496ec3392968969cab8549f96ff30652c9e56885329315f6bb"
 "checksum cargo_metadata 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)" = "46e3374c604fb39d1a2f35ed5e4a4e30e60d01fab49446e08f1b3e9a90aef202"
@@ -1801,7 +1793,7 @@ dependencies = [
 "checksum chalk-solve 0.1.0 (git+https://github.com/rust-lang/chalk.git?rev=ff65b5ac9860f3c36bd892c865ab23d5ff0bbae5)" = "<none>"
 "checksum clicolors-control 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "90082ee5dcdd64dc4e9e0d37fbf3ee325419e39c0092191e0393df65518f741e"
 "checksum cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
-"checksum console 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)" = "f5d540c2d34ac9dd0deb5f3b5f54c36c79efa78f6b3ad19106a554d07a7b5d9f"
+"checksum console 0.9.2 (registry+https://github.com/rust-lang/crates.io-index)" = "45e0f3986890b3acbc782009e2629dfe2baa430ac091519ce3be26164a2ae6c0"
 "checksum crossbeam 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)" = "69323bff1fb41c635347b8ead484a5ca6c3f11914d784170b158d8449ab07f8e"
 "checksum crossbeam-channel 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "acec9a3b0b3559f15aee4f90746c4e5e293b701c0f7d3925d24e01645267b68c"
 "checksum crossbeam-deque 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)" = "c3aa945d63861bfe624b55d153a39684da1e8c0bc8fba932f7ee3a3c16cea3ca"
@@ -1830,15 +1822,14 @@ dependencies = [
 "checksum globset 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)" = "925aa2cac82d8834e2b2a4415b6f6879757fb5c0928fc445ae76461a12eed8f2"
 "checksum heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "20564e78d53d2bb135c343b3f47714a56af2061f1c928fdb541dc7b9fdd94205"
 "checksum hermit-abi 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "eff2656d88f158ce120947499e971d743c05dbcbed62e5bd2f38f1698bbc3772"
-"checksum humantime 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "df004cfca50ef23c36850aaaa59ad52cc70d0e90243c3c7737a4dd32dc7a3c4f"
 "checksum idna 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "02e2673c30ee86b5b96a9cb52ad15718aa1f966f5ab9ad54a8b95d5ca33120a9"
 "checksum indexmap 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0b54058f0a6ff80b6803da8faf8997cde53872b38f4023728f6830b06cd3c0dc"
 "checksum inotify 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "24e40d6fd5d64e2082e0c796495c8ef5ad667a96d03e5aaa0becfd9d47bcbfb8"
 "checksum inotify-sys 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "e74a1aa87c59aeff6ef2cc2fa62d41bc43f54952f55652656b18a02fd5e356c0"
-"checksum insta 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0d499dc062e841590a67230d853bce62d0abeb91304927871670b7c55c461349"
+"checksum insta 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d07d2003a61f1eae49feeb2aea003d0da6c80587c20ac505d695805c744d4847"
 "checksum iovec 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "b2b3ea6ff95e175473f8ffe6a7eb7c00d054240321b84c57051175fe3c1e075e"
 "checksum itertools 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f56a2d0bc861f9165be4eb3442afd3c236d8a98afd426f65d92324ae1091a484"
-"checksum itoa 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)" = "501266b7edd0174f8530248f87f99c88fbe60ca4ef3dd486835b8d8d53136f7f"
+"checksum itoa 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)" = "b8b7a7c0c47db5545ed3fef7468ee7bb5b74691498139e4b3f6a20685dc6dd8e"
 "checksum jemalloc-ctl 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "c502a5ff9dd2924f1ed32ba96e3b65735d837b4bfd978d3161b1702e66aca4b7"
 "checksum jemalloc-sys 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "0d3b9f3f5c9b31aa0f5ed3260385ac205db665baa41d49bb8338008ae94ede45"
 "checksum jemallocator 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "43ae63fcfc45e99ab3d1b29a46782ad679e98436c3169d15a167a1108a724b69"
@@ -1853,7 +1844,7 @@ dependencies = [
 "checksum lock_api 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "79b2de95ecb4691949fea4716ca53cdbcfccb2c612e19644a8bad05edcf9f47b"
 "checksum log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)" = "14b6052be84e6b71ab17edffc2eeabf5c2c3ae1fdb464aae35ac50c67a44e1f7"
 "checksum lsp-server 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "5383e043329615624bbf45e1ba27bd75c176762b2592855c659bc28ac580a06b"
-"checksum lsp-types 0.69.0 (registry+https://github.com/rust-lang/crates.io-index)" = "cd78b254376c0734bb75c200616e256adbf2c3685497fcc1124db9daf5958630"
+"checksum lsp-types 0.70.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ef197b24cb3f12fc3984667a505691fec9d683204ddff56f12b2d1940e09a988"
 "checksum matches 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "7ffc5c5338469d4d3ea17d269fa8ea3512ad247247c30bd2df69e68309ed0a08"
 "checksum memchr 2.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3197e20c7edb283f87c071ddfc7a2cca8f8e0b888c242959846a6fce03c72223"
 "checksum memoffset 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "75189eb85871ea5c2e2c15abbdd541185f63b408415e5051f5cac122d8c774b9"
@@ -1864,7 +1855,7 @@ dependencies = [
 "checksum notify 4.0.15 (registry+https://github.com/rust-lang/crates.io-index)" = "80ae4a7688d1fab81c5bf19c64fc8db920be8d519ce6336ed4e7efe024724dbd"
 "checksum num-traits 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "c62be47e61d1842b9170f0fdeec8eba98e60e90e5446449a0545e5152acd7096"
 "checksum num_cpus 1.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "46203554f085ff89c235cd12f7075f3233af9b11ed7c9e16dfe2560d03313ce6"
-"checksum once_cell 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f5941ec2d5ee5916c709580d71553b81a633df245bcc73c04dcbd62152ceefc4"
+"checksum once_cell 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b1c601810575c99596d4afc46f78a678c80105117c379eb3650cf99b8a21ce5b"
 "checksum ordermap 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "a86ed3f5f244b372d6b1a00b72ef7f8876d0bc6a78a4c9985c53614041512063"
 "checksum parking_lot 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "92e98c49ab0b7ce5b222f2cc9193fc4efe11c6d0bd4f648e374684a6857b1cfc"
 "checksum parking_lot_core 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7582838484df45743c8434fbff785e8edf260c28748353d44bc0da32e0ceabf1"
@@ -1875,8 +1866,8 @@ dependencies = [
 "checksum pico-args 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "3ad1f1b834a05d42dae330066e9699a173b28185b3bdc3dbf14ca239585de8cc"
 "checksum ppv-lite86 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "74490b50b9fbe561ac330df47c08f3f33073d2d00c150f719147d7c54522fa1b"
 "checksum proc-macro-hack 0.5.11 (registry+https://github.com/rust-lang/crates.io-index)" = "ecd45702f76d6d3c75a80564378ae228a85f0b59d2f3ed43c91b4a69eb2ebfc5"
-"checksum proc-macro2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)" = "0319972dcae462681daf4da1adeeaa066e3ebd29c69be96c6abb1259d2ee2bcc"
-"checksum proptest 0.9.4 (registry+https://github.com/rust-lang/crates.io-index)" = "cf147e022eacf0c8a054ab864914a7602618adba841d800a9a9868a5237a529f"
+"checksum proc-macro2 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)" = "3acb317c6ff86a4e579dfa00fc5e6cca91ecbb4e7eb2df0468805b674eb88548"
+"checksum proptest 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)" = "bf6147d103a7c9d7598f4105cf049b15c99e2ecd93179bf024f0fd349be5ada4"
 "checksum quick-error 1.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
 "checksum quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "053a8c8bcc71fcce321828dc897a98ab9760bef03a4fc36693c231e5b3216cfe"
 "checksum ra_vfs 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "bc898f237e4b4498959ae0100c688793a23e77624d44ef710ba70094217f98e0"
@@ -1917,14 +1908,14 @@ dependencies = [
 "checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 "checksum serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)" = "414115f25f818d7dfccec8ee535d76949ae78584fc4f79a6f45a904bf8ab4449"
 "checksum serde_derive 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)" = "128f9e303a5a29922045a830221b8f78ec74a5f544944f3d5984f8ec3895ef64"
-"checksum serde_json 1.0.44 (registry+https://github.com/rust-lang/crates.io-index)" = "48c575e0cc52bdd09b47f330f646cf59afc586e9c4e3ccd6fc1f625b8ea1dad7"
+"checksum serde_json 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)" = "eab8f15f15d6c41a154c1b128a22f2dfabe350ef53c40953d84e36155c91192b"
 "checksum serde_repr 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "cd02c7587ec314570041b2754829f84d873ced14a96d1fd1823531e11db40573"
 "checksum serde_yaml 0.8.11 (registry+https://github.com/rust-lang/crates.io-index)" = "691b17f19fc1ec9d94ec0b5864859290dff279dbd7b03f017afda54eb36c3c35"
 "checksum slab 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "c111b5bd5695e56cffe5129854aa230b39c93a305372fdbb2668ca2394eea9f8"
 "checksum smallvec 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "44e59e0c9fa00817912ae6e4e6e3c4fe04455e75699d06eedc7d85917ed8e8f4"
 "checksum smol_str 0.1.15 (registry+https://github.com/rust-lang/crates.io-index)" = "34836c9a295c62c2ce3514471117c5cb269891e8421b2aafdd910050576c4d8b"
 "checksum superslice 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ab16ced94dbd8a46c82fd81e3ed9a8727dac2977ea869d217bcc4ea1f122e81f"
-"checksum syn 1.0.13 (registry+https://github.com/rust-lang/crates.io-index)" = "1e4ff033220a41d1a57d8125eab57bf5263783dfdcc18688b1dacc6ce9651ef8"
+"checksum syn 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)" = "af6f3550d8dff9ef7dc34d384ac6f107e5d31c8f57d9f28e0081503f547ac8f5"
 "checksum tempfile 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e24d9338a0a5be79593e2fa15a648add6138caa803e2d5bc782c371732ca9"
 "checksum termios 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "72b620c5ea021d75a735c943269bb07d30c9b77d6ac6b236bc8b5c496ef05625"
 "checksum text_unit 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "e08bbcb7a3adbda0eb23431206b653bdad3d8dea311e72d36bf2215e27a42579"
@@ -1933,7 +1924,7 @@ dependencies = [
 "checksum threadpool 1.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e2f0c90a5f3459330ac8bc0d2f879c693bb7a2f59689c1083fc4ef83834da865"
 "checksum unicase 2.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "50f37be617794602aabbeee0be4f259dc1778fabe05e2d67ee8f79326d5cb4f6"
 "checksum unicode-bidi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "49f2bd0c6468a8230e1db229cff8029217cf623c767ea5d60bfbd42729ea54d5"
-"checksum unicode-normalization 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)" = "b561e267b2326bb4cebfc0ef9e68355c7abe6c6f522aeac2f5bf95d56c59bdcf"
+"checksum unicode-normalization 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)" = "5479532badd04e128284890390c1e876ef7a993d0570b3597ae43dfa1d59afa4"
 "checksum unicode-segmentation 1.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e83e153d1053cbb5a118eeff7fd5be06ed99153f00dbcd8ae310c5fb2b22edc0"
 "checksum unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "826e7639553986605ec5979c7dd957c7895e93eabed50ab2ffa7f6128a75097c"
 "checksum url 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "829d4a8476c35c9bf0bbce5a3b23f4106f79728039b726d292bb93bc106787cb"
diff --git a/bors.toml b/bors.toml
index bf5553df4..0bc71860f 100644
--- a/bors.toml
+++ b/bors.toml
@@ -1,6 +1,6 @@
 status = [
     "Rust (ubuntu-latest)",
-    # "Rust (windows-latest)",
+    "Rust (windows-latest)",
     "Rust (macos-latest)",
     "TypeScript"
 ]
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/add_explicit_type.rs b/crates/ra_assists/src/assists/add_explicit_type.rs
index f9f826b88..38a351a54 100644
--- a/crates/ra_assists/src/assists/add_explicit_type.rs
+++ b/crates/ra_assists/src/assists/add_explicit_type.rs
@@ -1,7 +1,7 @@
 use hir::{db::HirDatabase, HirDisplay};
 use ra_syntax::{
     ast::{self, AstNode, LetStmt, NameOwner},
-    T,
+    TextRange, T,
 };
 
 use crate::{Assist, AssistCtx, AssistId};
@@ -34,6 +34,14 @@ pub(crate) fn add_explicit_type(ctx: AssistCtx<impl HirDatabase>) -> Option<Assi
     // The binding must have a name
     let name = pat.name()?;
     let name_range = name.syntax().text_range();
+    // Assist should only be applicable if cursor is between 'let' and '='
+    let stmt_range = stmt.syntax().text_range();
+    let eq_range = stmt.eq_token()?.text_range();
+    let let_range = TextRange::from_to(stmt_range.start(), eq_range.start());
+    let cursor_in_range = ctx.frange.range.is_subrange(&let_range);
+    if !cursor_in_range {
+        return None;
+    }
     // Assist not applicable if the type has already been specified
     if stmt.syntax().children_with_tokens().any(|child| child.kind() == T![:]) {
         return None;
@@ -109,4 +117,20 @@ mod tests {
     fn add_explicit_type_not_applicable_if_specified_ty_is_tuple() {
         check_assist_not_applicable(add_explicit_type, "fn f() { let a<|>: (i32, i32) = (3, 4); }");
     }
+
+    #[test]
+    fn add_explicit_type_not_applicable_if_cursor_after_equals() {
+        check_assist_not_applicable(
+            add_explicit_type,
+            "fn f() {let a =<|> match 1 {2 => 3, 3 => 5};}",
+        )
+    }
+
+    #[test]
+    fn add_explicit_type_not_applicable_if_cursor_before_let() {
+        check_assist_not_applicable(
+            add_explicit_type,
+            "fn f() <|>{let a = match 1 {2 => 3, 3 => 5};}",
+        )
+    }
 }
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..9163cc662
--- /dev/null
+++ b/crates/ra_assists/src/assists/auto_import.rs
@@ -0,0 +1,222 @@
+use hir::db::HirDatabase;
+use ra_syntax::{
+    ast::{self, AstNode},
+    SmolStr, SyntaxElement,
+    SyntaxKind::{NAME_REF, 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: ast::Path = ctx.find_node_at_offset()?;
+    let module = path.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.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()?;
+    let path_to_import = ctx.covering_element().ancestors().find_map(ast::Path::cast)?;
+    if source_analyzer.resolve_path(ctx.db, &path_to_import).is_some() {
+        return None;
+    }
+
+    let name_to_import = &find_applicable_name_ref(ctx.covering_element())?.syntax().to_string();
+    let proposed_imports = imports_locator
+        .find_imports(&name_to_import.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 find_applicable_name_ref(element: SyntaxElement) -> Option<ast::NameRef> {
+    if element.ancestors().find(|ancestor| ancestor.kind() == USE_ITEM).is_some() {
+        None
+    } else if element.kind() == NAME_REF {
+        Some(element.as_node().cloned().and_then(ast::NameRef::cast)?)
+    } else {
+        let parent = element.parent()?;
+        if parent.kind() == NAME_REF {
+            Some(ast::NameRef::cast(parent)?)
+        } else {
+            None
+        }
+    }
+}
+
+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"
+            PubStruct<|>
+
+            pub mod PubMod1 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod2 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod3 {
+                pub struct PubStruct;
+            }
+            ",
+            r"
+            use PubMod1::PubStruct;
+
+            PubStruct<|>
+
+            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 45e0f983f..83527d904 100644
--- a/crates/ra_assists/src/assists/inline_local_variable.rs
+++ b/crates/ra_assists/src/assists/inline_local_variable.rs
@@ -23,7 +23,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     (1 + 2) * 4;
 // }
 // ```
-pub(crate) fn inline_local_varialbe(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+pub(crate) fn inline_local_variable(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     let let_stmt = ctx.find_node_at_offset::<ast::LetStmt>()?;
     let bind_pat = match let_stmt.pat()? {
         ast::Pat::BindPat(pat) => pat,
@@ -47,6 +47,9 @@ pub(crate) fn inline_local_varialbe(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()];
 
@@ -117,7 +120,7 @@ mod tests {
     #[test]
     fn test_inline_let_bind_literal_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn bar(a: usize) {}
 fn foo() {
@@ -151,7 +154,7 @@ fn foo() {
     #[test]
     fn test_inline_let_bind_bin_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn bar(a: usize) {}
 fn foo() {
@@ -185,7 +188,7 @@ fn foo() {
     #[test]
     fn test_inline_let_bind_function_call_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn bar(a: usize) {}
 fn foo() {
@@ -219,7 +222,7 @@ fn foo() {
     #[test]
     fn test_inline_let_bind_cast_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn bar(a: usize): usize { a }
 fn foo() {
@@ -253,7 +256,7 @@ fn foo() {
     #[test]
     fn test_inline_let_bind_block_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = { 10 + 1 };
@@ -285,7 +288,7 @@ fn foo() {
     #[test]
     fn test_inline_let_bind_paren_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = ( 10 + 1 );
@@ -317,7 +320,7 @@ fn foo() {
     #[test]
     fn test_not_inline_mut_variable() {
         check_assist_not_applicable(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let mut a<|> = 1 + 1;
@@ -329,7 +332,7 @@ fn foo() {
     #[test]
     fn test_call_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = bar(10 + 1);
@@ -347,7 +350,7 @@ fn foo() {
     #[test]
     fn test_index_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let x = vec![1, 2, 3];
@@ -367,7 +370,7 @@ fn foo() {
     #[test]
     fn test_method_call_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let bar = vec![1];
@@ -387,7 +390,7 @@ fn foo() {
     #[test]
     fn test_field_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 struct Bar {
     foo: usize
@@ -415,7 +418,7 @@ fn foo() {
     #[test]
     fn test_try_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() -> Option<usize> {
     let bar = Some(1);
@@ -437,7 +440,7 @@ fn foo() -> Option<usize> {
     #[test]
     fn test_ref_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let bar = 10;
@@ -455,7 +458,7 @@ fn foo() {
     #[test]
     fn test_tuple_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = (10, 20);
@@ -471,7 +474,7 @@ fn foo() {
     #[test]
     fn test_array_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = [1, 2, 3];
@@ -487,7 +490,7 @@ fn foo() {
     #[test]
     fn test_paren() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = (10 + 20);
@@ -505,7 +508,7 @@ fn foo() {
     #[test]
     fn test_path_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let d = 10;
@@ -525,7 +528,7 @@ fn foo() {
     #[test]
     fn test_block_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = { 10 };
@@ -543,7 +546,7 @@ fn foo() {
     #[test]
     fn test_used_in_different_expr1() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = 10 + 20;
@@ -565,7 +568,7 @@ fn foo() {
     #[test]
     fn test_used_in_for_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = vec![10, 20];
@@ -581,7 +584,7 @@ fn foo() {
     #[test]
     fn test_used_in_while_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = 1 > 0;
@@ -597,7 +600,7 @@ fn foo() {
     #[test]
     fn test_used_in_break_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = 1 + 1;
@@ -617,7 +620,7 @@ fn foo() {
     #[test]
     fn test_used_in_return_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = 1 > 0;
@@ -633,7 +636,7 @@ fn foo() {
     #[test]
     fn test_used_in_match_expr() {
         check_assist(
-            inline_local_varialbe,
+            inline_local_variable,
             "
 fn foo() {
     let a<|> = 1 > 0;
@@ -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 d45b58966..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;
@@ -157,7 +206,7 @@ mod assists {
             add_import::add_import,
             add_missing_impl_members::add_missing_impl_members,
             add_missing_impl_members::add_missing_default_members,
-            inline_local_variable::inline_local_varialbe,
+            inline_local_variable::inline_local_variable,
             move_guard::move_guard_to_arm_body,
             move_guard::move_arm_cond_to_match_guard,
             move_bounds::move_bounds_to_where_clause,
@@ -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..49e06e0d3 100644
--- a/crates/ra_cargo_watch/Cargo.toml
+++ b/crates/ra_cargo_watch/Cargo.toml
@@ -6,12 +6,12 @@ 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"
 
 [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..bbe634603 100644
--- a/crates/ra_cargo_watch/src/lib.rs
+++ b/crates/ra_cargo_watch/src/lib.rs
@@ -7,7 +7,6 @@ use lsp_types::{
     Diagnostic, Url, WorkDoneProgress, WorkDoneProgressBegin, WorkDoneProgressEnd,
     WorkDoneProgressReport,
 };
-use parking_lot::RwLock;
 use std::{
     collections::HashMap,
     path::PathBuf,
@@ -38,7 +37,7 @@ 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 +45,7 @@ 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 +58,7 @@ 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 +86,7 @@ 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>>,
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/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_ty/Cargo.toml b/crates/ra_hir_ty/Cargo.toml
index 60793db44..d229639d9 100644
--- a/crates/ra_hir_ty/Cargo.toml
+++ b/crates/ra_hir_ty/Cargo.toml
@@ -28,4 +28,4 @@ chalk-ir =      { git = "https://github.com/rust-lang/chalk.git", rev = "ff65b5a
 lalrpop-intern = "0.15.1"
 
 [dev-dependencies]
-insta = "0.12.0"
+insta = "0.13.0"
diff --git a/crates/ra_hir_ty/src/display.rs b/crates/ra_hir_ty/src/display.rs
index 37def7c03..d1ff85f0f 100644
--- a/crates/ra_hir_ty/src/display.rs
+++ b/crates/ra_hir_ty/src/display.rs
@@ -9,7 +9,7 @@ pub struct HirFormatter<'a, 'b, DB> {
     fmt: &'a mut fmt::Formatter<'b>,
     buf: String,
     curr_size: usize,
-    max_size: Option<usize>,
+    pub(crate) max_size: Option<usize>,
     omit_verbose_types: bool,
 }
 
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index d63f862dc..908e4862d 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -855,7 +855,12 @@ impl HirDisplay for ApplicationTy {
             }
             TypeCtor::Ref(m) => {
                 let t = self.parameters.as_single();
-                write!(f, "&{}{}", m.as_keyword_for_ref(), t.display(f.db))?;
+                let ty_display = if f.omit_verbose_types() {
+                    t.display_truncated(f.db, f.max_size)
+                } else {
+                    t.display(f.db)
+                };
+                write!(f, "&{}{}", m.as_keyword_for_ref(), ty_display)?;
             }
             TypeCtor::Never => write!(f, "!")?,
             TypeCtor::Tuple { .. } => {
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..ce617840c 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 {
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/inlay_hints.rs b/crates/ra_ide/src/inlay_hints.rs
index 236557541..393ca9447 100644
--- a/crates/ra_ide/src/inlay_hints.rs
+++ b/crates/ra_ide/src/inlay_hints.rs
@@ -245,6 +245,7 @@ struct Test<K, T = u8> {
 
 fn main() {
     let zz = Test { t: 23, k: 33 };
+    let zz_ref = &zz;
 }"#,
         );
 
@@ -255,6 +256,11 @@ fn main() {
                 kind: TypeHint,
                 label: "Test<i32>",
             },
+            InlayHint {
+                range: [105; 111),
+                kind: TypeHint,
+                label: "&Test<i32>",
+            },
         ]
         "###
         );
@@ -374,6 +380,7 @@ fn main() {
 
     let multiply = |a, b, c, d| a * b * c * d;
     let _: i32 = multiply(1, 2, 3, 4);
+    let multiply_ref = &multiply;
 
     let return_42 = || 42;
 }"#,
@@ -417,7 +424,12 @@ fn main() {
                 label: "i32",
             },
             InlayHint {
-                range: [201; 210),
+                range: [200; 212),
+                kind: TypeHint,
+                label: "&|…| -> i32",
+            },
+            InlayHint {
+                range: [235; 244),
                 kind: TypeHint,
                 label: "|| -> i32",
             },
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/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_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..15bf519c9 100644
--- a/crates/ra_lsp_server/src/main_loop.rs
+++ b/crates/ra_lsp_server/src/main_loop.rs
@@ -29,9 +29,6 @@ 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 +57,25 @@ 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 +184,7 @@ 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 +226,7 @@ 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)
@@ -371,7 +387,8 @@ 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();
@@ -586,12 +603,14 @@ fn on_notification(
 
 fn on_check_task(
     task: CheckTask,
-    world_state: &WorldState,
+    world_state: &mut WorldState,
     task_sender: &Sender<Task>,
 ) -> Result<()> {
     match task {
         CheckTask::ClearDiagnostics => {
-            let cleared_files = world_state.check_watcher.state.write().clear();
+            let state = Arc::get_mut(&mut world_state.check_watcher.state)
+                .expect("couldn't get check watcher state as mutable");
+            let cleared_files = state.clear();
 
             // Send updated diagnostics for each cleared file
             for url in cleared_files {
@@ -600,11 +619,9 @@ fn on_check_task(
         }
 
         CheckTask::AddDiagnostic(url, diagnostic) => {
-            world_state
-                .check_watcher
-                .state
-                .write()
-                .add_diagnostic_with_fixes(url.clone(), diagnostic);
+            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);
 
             // We manually send a diagnostic update when the watcher asks
             // us to, to avoid the issue of having to change the file to
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_parser/src/lib.rs b/crates/ra_parser/src/lib.rs
index 65134277e..81055746b 100644
--- a/crates/ra_parser/src/lib.rs
+++ b/crates/ra_parser/src/lib.rs
@@ -27,7 +27,7 @@ pub use syntax_kind::SyntaxKind;
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct ParseError(pub String);
 
-/// `TokenSource` abstracts the source of the tokens parser operates one.
+/// `TokenSource` abstracts the source of the tokens parser operates on.
 ///
 /// Hopefully this will allow us to treat text and token trees in the same way!
 pub trait TokenSource {
@@ -43,7 +43,7 @@ pub trait TokenSource {
     fn is_keyword(&self, kw: &str) -> bool;
 }
 
-/// `TokenCursor` abstracts the cursor of `TokenSource` operates one.
+/// `Token` abstracts the cursor of `TokenSource` operates on.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct Token {
     /// What is the current token?
diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
index da541005a..c7973ddf4 100644
--- a/crates/ra_prof/src/lib.rs
+++ b/crates/ra_prof/src/lib.rs
@@ -106,6 +106,21 @@ 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/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 6da4b1309..539759450 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -305,44 +305,39 @@ impl ast::Literal {
             .unwrap()
     }
 
+    fn find_suffix(text: &str, possible_suffixes: &[&str]) -> Option<SmolStr> {
+        possible_suffixes
+            .iter()
+            .find(|&suffix| text.ends_with(suffix))
+            .map(|&suffix| SmolStr::new(suffix))
+    }
+
     pub fn kind(&self) -> LiteralKind {
-        match self.token().kind() {
-            INT_NUMBER => {
-                let int_suffix_list = [
-                    "isize", "i128", "i64", "i32", "i16", "i8", "usize", "u128", "u64", "u32",
-                    "u16", "u8",
-                ];
+        const INT_SUFFIXES: [&'static str; 12] = [
+            "u64", "u32", "u16", "u8", "usize", "isize", "i64", "i32", "i16", "i8", "u128", "i128",
+        ];
+        const FLOAT_SUFFIXES: [&'static str; 2] = ["f32", "f64"];
 
+        let token = self.token();
+
+        match token.kind() {
+            INT_NUMBER => {
+                // FYI: there was a bug here previously, thus an if statement bellow is necessary.
                 // The lexer treats e.g. `1f64` as an integer literal. See
                 // https://github.com/rust-analyzer/rust-analyzer/issues/1592
                 // and the comments on the linked PR.
-                let float_suffix_list = ["f32", "f64"];
-
-                let text = self.token().text().to_string();
 
-                let float_suffix = float_suffix_list
-                    .iter()
-                    .find(|&s| text.ends_with(s))
-                    .map(|&suf| SmolStr::new(suf));
+                let text = token.text();
 
-                if float_suffix.is_some() {
-                    LiteralKind::FloatNumber { suffix: float_suffix }
+                if let suffix @ Some(_) = Self::find_suffix(&text, &FLOAT_SUFFIXES) {
+                    LiteralKind::FloatNumber { suffix }
                 } else {
-                    let suffix = int_suffix_list
-                        .iter()
-                        .find(|&s| text.ends_with(s))
-                        .map(|&suf| SmolStr::new(suf));
-                    LiteralKind::IntNumber { suffix }
+                    LiteralKind::IntNumber { suffix: Self::find_suffix(&text, &INT_SUFFIXES) }
                 }
             }
             FLOAT_NUMBER => {
-                let allowed_suffix_list = ["f64", "f32"];
-                let text = self.token().text().to_string();
-                let suffix = allowed_suffix_list
-                    .iter()
-                    .find(|&s| text.ends_with(s))
-                    .map(|&suf| SmolStr::new(suf));
-                LiteralKind::FloatNumber { suffix }
+                let text = token.text();
+                LiteralKind::FloatNumber { suffix: Self::find_suffix(&text, &FLOAT_SUFFIXES) }
             }
             STRING | RAW_STRING => LiteralKind::String,
             T![true] | T![false] => LiteralKind::Bool,
diff --git a/crates/ra_syntax/src/ast/extensions.rs b/crates/ra_syntax/src/ast/extensions.rs
index d9666cdca..cb0aee422 100644
--- a/crates/ra_syntax/src/ast/extensions.rs
+++ b/crates/ra_syntax/src/ast/extensions.rs
@@ -234,6 +234,10 @@ impl ast::LetStmt {
             Some(node) => node.kind() == T![;],
         }
     }
+
+    pub fn eq_token(&self) -> Option<SyntaxToken> {
+        self.syntax().children_with_tokens().find(|t| t.kind() == EQ).and_then(|it| it.into_token())
+    }
 }
 
 impl ast::ExprStmt {
diff --git a/docs/dev/syntax.md b/docs/dev/syntax.md
new file mode 100644
index 000000000..0a4554c55
--- /dev/null
+++ b/docs/dev/syntax.md
@@ -0,0 +1,535 @@
+# Syntax in rust-analyzer
+
+## About the guide
+
+This guide describes the current state of syntax trees and parsing in rust-analyzer as of 2020-01-09 ([link to commit](https://github.com/rust-analyzer/rust-analyzer/tree/cf5bdf464cad7ceb9a67e07985a3f4d3799ec0b6)).
+
+## Source Code
+
+The things described are implemented in two places
+
+* [rowan](https://github.com/rust-analyzer/rowan/tree/v0.9.0) -- a generic library for rowan syntax trees.
+* [ra_syntax](https://github.com/rust-analyzer/rust-analyzer/tree/cf5bdf464cad7ceb9a67e07985a3f4d3799ec0b6/crates/ra_syntax) crate inside rust-analyzer which wraps `rowan` into rust-analyzer specific API.
+  Nothing in rust-analyzer except this crate knows about `rowan`.
+* [ra_parser](https://github.com/rust-analyzer/rust-analyzer/tree/cf5bdf464cad7ceb9a67e07985a3f4d3799ec0b6/crates/ra_parser) crate parses input tokens into an `ra_syntax` tree
+
+## Design Goals
+
+* Syntax trees are lossless, or full fidelity. All comments and whitespace are preserved.
+* Syntax trees are semantic-less. They describe *strictly* the structure of a sequence of characters, they don't have hygiene, name resolution or type information attached.
+* Syntax trees are simple value type. It is possible to create trees for a syntax without any external context. 
+* Syntax trees have intuitive traversal API (parent, children, siblings, etc).
+* Parsing is lossless (even if the input is invalid, the tree produced by the parser represents it exactly).
+* Parsing is resilient (even if the input is invalid, parser tries to see as much syntax tree fragments in the input as it can).
+* Performance is important, it's OK to use `unsafe` if it means better memory/cpu usage.
+* Keep the parser and the syntax tree isolated from each other, such that they can vary independently.
+
+## Trees
+
+### Overview
+
+The syntax tree consists of three layers:
+
+* GreenNodes
+* SyntaxNodes (aka RedNode)
+* AST
+
+Of these, only GreenNodes store the actual data, the other two layers are (non-trivial) views into green tree. 
+Red-green terminology comes from Roslyn ([link](https://docs.microsoft.com/en-ie/archive/blogs/ericlippert/persistence-facades-and-roslyns-red-green-trees)) and gives the name to the `rowan` library. Green and syntax nodes are defined in rowan, ast is defined in rust-analyzer.
+
+Syntax trees are a semi-transient data structure.
+In general, frontend does not keep syntax trees for all files in memory.
+Instead, it *lowers* syntax trees to more compact and rigid representation, which is not full-fidelity, but which can be mapped back to a syntax tree if so desired. 
+
+
+### GreenNode
+
+GreenNode is a purely-functional tree with arbitrary arity. Conceptually, it is equivalent to the following run of the mill struct:
+
+```rust
+#[derive(PartialEq, Eq, Clone, Copy)]
+struct SyntaxKind(u16);
+
+#[derive(PartialEq, Eq, Clone)]
+struct Node {
+    kind: SyntaxKind,
+    text_len: usize,
+    children: Vec<Arc<Either<Node, Token>>>,
+}
+
+#[derive(PartialEq, Eq, Clone)]
+struct Token {
+    kind: SyntaxKind,
+    text: String,
+}
+```
+
+All the difference bettwen the above sketch and the real implementation are strictly due to optimizations. 
+
+Points of note:
+* The tree is untyped. Each node has a "type tag", `SyntaxKind`.
+* Interior and leaf nodes are distinguished on the type level.
+* Trivia and non-trivia tokens are not distinguished on the type level.
+* Each token carries its full text.
+* The original text can be recovered by concatenating the texts of all tokens in order.
+* Accessing a child of particular type (for example, parameter list of a function) generarly involves linerary traversing the children, looking for a specific `kind`.
+* Modifying the tree is roughly `O(depth)`. 
+  We don't make special efforts to guarantree that the depth is not liner, but, in practice, syntax trees are branchy and shallow.
+* If mandatory (grammar wise) node is missing from the input, it's just missing from the tree.
+* If an extra erroneous input is present, it is wrapped into a node with `ERROR` kind, and treated just like any other node.
+* Parser errors are not a part of syntax tree.
+
+An input like `fn f() { 90 + 2 }` might be parsed as
+
+```
+FN_DEF@[0; 17)
+  FN_KW@[0; 2) "fn"
+  WHITESPACE@[2; 3) " "
+  NAME@[3; 4)
+    IDENT@[3; 4) "f"
+  PARAM_LIST@[4; 6)
+    L_PAREN@[4; 5) "("
+    R_PAREN@[5; 6) ")"
+  WHITESPACE@[6; 7) " "
+  BLOCK_EXPR@[7; 17)
+    BLOCK@[7; 17)
+      L_CURLY@[7; 8) "{"
+      WHITESPACE@[8; 9) " "
+      BIN_EXPR@[9; 15)
+        LITERAL@[9; 11)
+          INT_NUMBER@[9; 11) "90"
+        WHITESPACE@[11; 12) " "
+        PLUS@[12; 13) "+"
+        WHITESPACE@[13; 14) " "
+        LITERAL@[14; 15)
+          INT_NUMBER@[14; 15) "2"
+      WHITESPACE@[15; 16) " "
+      R_CURLY@[16; 17) "}"
+```
+
+#### Optimizations
+
+(significant amount of implementation work here was done by [CAD97](https://github.com/cad97)).
+
+To reduce the amount of allocations, the GreenNode is a DST, which uses a single allocation for header and children. Thus, it is only usable behind a pointer
+
+```
+*-----------+------+----------+------------+--------+--------+-----+--------*
+| ref_count | kind | text_len | n_children | child1 | child2 | ... | childn |
+*-----------+------+----------+------------+--------+--------+-----+--------*
+```
+
+To more compactly store the children, we box *both* interior nodes and tokens, and represent
+`Either<Arc<Node>, Arc<Token>>` as a single pointer with a tag in the last bit.
+
+To avoid allocating EVERY SINGLE TOKEN on the heap, syntax trees use interning. 
+Because the tree is fully imutable, it's valid to structuraly share subtrees.
+For example, in `1 + 1`, there will be a *single* token for `1` with ref count 2; the same goes for the ` ` whitespace token. 
+Interior nodes are shared as well (for example in `(1 + 1) * (1 + 1)`). 
+
+Note that, the result of the interning is an `Arc<Node>`. 
+That is, it's not an index into interning table, so you don't have to have the table around to do anything with the tree.
+Each tree is fully self-contained (although different trees might share parts).
+Currently, the interner is created per-file, but it will be easy to use a per-thread or per-some-contex one. 
+
+We use a `TextUnit`, a newtyped `u32`, to store the length of the text.
+
+We currently use `SmolStr`, an small object optimized string to store text. 
+This was mostly relevant *before* we implmented tree interning, to avoid allocating common keywords and identifiers. We should switch to storing text data alongside the interned tokens. 
+
+#### Alternative designs
+
+##### Dealing with trivia
+
+In the above model, whitespace is not treated specially.
+Another alternative (used by swift and roslyn) is to explicitly divide the set of tokens into trivia and non-trivia tokens, and represent non-trivia tokens as
+
+```rust
+struct Token {
+    kind: NonTriviaTokenKind
+    text: String,
+    leading_trivia: Vec<TriviaToken>,
+    trailing_trivia: Vec<TriviaToken>,
+}
+```
+
+The tree then contains only non-trivia tokens. 
+
+Another approach (from Dart) is to, in addition to a syntax tree, link all the tokens into a bidirectional link list. 
+That way, the tree again contains only non-trivia tokens.
+
+Explicit trivia nodes, like in `rowan`, are used by IntelliJ.
+
+##### Accessing Children
+
+As noted before, accesing a specific child in the node requires a linear traversal of the children (though we can skip tokens, beacuse the tag is encoded in the pointer itself).
+It is possible to recover O(1) access with another representation.
+We explicitly store optional and missing (required by the grammar, but not present) nodes.
+That is, we use `Option<Node>` for children. 
+We also remove trivia tokens from the tree.
+This way, each child kind genrerally occupies a fixed position in a parent, and we can use index access to fetch it. 
+The cost is that we now need to allocate space for all not-present optional nodes.
+So, `fn foo() {}` will have slots for visibility, unsafeness, attributes, abi and return type. 
+
+IntelliJ uses linear traversal.
+Roslyn and Swift do `O(1)` access.
+
+##### Mutable Trees
+
+IntelliJ uses mutable trees. 
+Overall, it creates a lot of additional complexity.
+However, the API for *editing* syntax trees is nice.
+
+For example the assist to move generic bounds to where clause has this code:
+
+```kotlin
+ for typeBound in typeBounds { 
+     typeBound.typeParamBounds?.delete() 
+}
+```
+
+Modeling this with immutable trees is possible, but annoying.
+
+### Syntax Nodes
+
+A function green tree is not super-convenient to use.
+The biggest problem is acessing parents (there are no parent pointers!).
+But there are also "identify" issues.
+Let's say you want to write a code which builds a list of expressions in a file: `fn collect_exrepssions(file: GreenNode) -> HashSet<GreenNode>`. 
+For the input like
+
+```rust
+fn main() {
+    let x = 90i8;
+    let x = x + 2;
+    let x = 90i64;
+    let x = x + 2;
+}
+```
+
+both copies of the `x + 2` expression are representing by equal (and, with interning in mind, actualy the same) green nodes.
+Green trees just can't differentiate between the two.
+
+`SyntaxNode` adds parent pointers and identify semantics to green nodes.
+They can be called cursors or [zippers](https://en.wikipedia.org/wiki/Zipper_(data_structure)) (fun fact: zipper is a derivative (as in ′) of a data structure).
+
+Conceptually, a `SyntaxNode` looks like this:
+
+```rust
+type SyntaxNode = Arc<SyntaxData>;
+
+struct SyntaxData {
+    offset: usize,
+    parent: Option<SyntaxNode>,
+    green: Arc<GreeNode>,
+}
+
+impl SyntaxNode {
+    fn new_root(root: Arc<GreenNode>) -> SyntaxNode {
+        Arc::new(SyntaxData {
+            offset: 0,
+            parent: None,
+            green: root,
+        })
+    }
+    fn parent(&self) -> Option<SyntaxNode> {
+        self.parent.clone()    
+    }
+    fn children(&self) -> impl Iterator<Item = SyntaxNode> {
+        let mut offset = self.offset
+        self.green.children().map(|green_child| {
+            let child_offset = offset;
+            offset += green_child.text_len;
+            Arc::new(SyntaxData {
+                offset: child_offset;
+                parent: Some(Arc::clone(self)),
+                green: Arc::clone(green_child),
+            })
+        })
+    }
+}
+
+impl PartialEq for SyntaxNode {
+    fn eq(&self, other: &SyntaxNode) {
+        self.offset == other.offset 
+            && Arc::ptr_eq(&self.green, &other.green)        
+    }
+}
+```
+
+Points of note:
+
+* SyntaxNode remembers its parent node (and, transitively, the path to the root of the tree)
+* SyntaxNode knows its *absolute* text offset in the whole file
+* Equality is based on identity. Comparing nodes from different trees does not make sense. 
+
+#### Optimization
+
+The reality is different though :-) 
+Traversal of trees is a common operation, and it makes sense to optimize it.
+In particular, the above code allocates and does atomic operations during a traversal.
+
+To get rid of atomics, `rowan` uses non thread-safe `Rc`.
+This is OK because trees traversals mostly (always, in case of rust-analyzer) run on a single thread. If you need to send a `SyntaxNode` to another thread, you can send a pair of **root**`GreenNode` (which is thread safe) and a `Range<usize>`. 
+The other thread can restore the `SyntaxNode` by traversing from the root green node and looking for a node with specified range. 
+You can also use the similar trick to store a `SyntaxNode`.
+That is, a data structure that holds a `(GreenNode, Range<usize>)` will be `Sync`.
+However rust-analyzer goes even further. 
+It treats trees as semi-transient and instead of storing a `GreenNode`, it generally stores just the id of the file from which the tree originated: `(FileId, Range<usize>)`.
+The `SyntaxNode` is the restored by reparsing the file and traversing it from root.
+With this trick, rust-analyzer holds only a small amount of trees in memory at the same time, which reduces memory usage.
+
+Additionally, only the root `SyntaxNode` owns an `Arc` to the (root) `GreenNode`.
+All other `SyntaxNode`s point to corresponding `GreenNode`s with a raw pointer. 
+They also point to the parent (and, consequently, to the root) with an owning `Rc`, so this is sound. 
+In other words, one needs *one* arc bump when initiating a traversal.
+
+To get rid of allocations, `rowan` takes advantage of `SyntaxNode: !Sync` and uses a thread-local free list of `SyntaxNode`s. 
+In a typical traversal, you only directly hold a few `SyntaxNode`s at a time (and their ancesstors indirectly), so a free list proportional to the depth of the tree removes all allocations in a typical case. 
+
+So, while traversal is not exactly incrementing a pointer, it's still prety cheep: tls + rc bump!
+
+Traversal also yields (cheap) owned nodes, which improves ergonomics quite a bit. 
+
+#### Alternative Designs
+
+##### Memoized RedNodes
+
+C# and Swift follow the design where the red nodes are memoized, which would look roughly like this in Rust:
+
+```rust
+type SyntaxNode = Arc<SyntaxData>;
+
+struct SyntaxData {
+    offset: usize,
+    parent: Option<SyntaxNode>,
+    green: Arc<GreeNode>,
+    children: Vec<OnceCell<SyntaxNode>>,
+}
+```
+
+This allows using true pointer equality for comparision of identities of `SyntaxNodes`.
+rust-analyzer used to have this design as well, but since we've switch to cursors. 
+The main problem with memoizing the red nodes is that it more than doubles the memory requirenments for fully realized syntax trees. 
+In contrast, cursors generally retain only a path to the root.
+C# combats increased memory usage by using weak references. 
+
+### AST
+
+`GreenTree`s are untyped and homogeneous, because it makes accomodating error nodes, arbitrary whitespace and comments natural, and because it makes possible to write generic tree traversals. 
+However, when working with a specific node, like a function definition, one would want a strongly typed API.
+
+This is what is provided by the AST layer. AST nodes are transparent wrappers over untyped syntax nodes:
+
+```rust
+pub trait AstNode {
+    fn cast(syntax: SyntaxNode) -> Option<Self>
+    where
+        Self: Sized;
+
+    fn syntax(&self) -> &SyntaxNode;
+}
+```
+
+Concrete nodes are generated (there are 117 of them), and look roughly like this:
+
+```rust
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct FnDef {
+    syntax: SyntaxNode,
+}
+
+impl AstNode for FnDef {
+    fn cast(syntax: SyntaxNode) -> Option<Self> {
+        match kind {
+            FN_DEF => Some(FnDef { syntax }),
+            _ => None,
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode {
+        &self.syntax
+    }
+}
+
+impl FnDef {
+    pub fn param_list(&self) -> Option<ParamList> { 
+        self.syntax.children().find_map(ParamList::cast)
+    }
+    pub fn ret_type(&self) -> Option<RetType> { 
+        self.syntax.children().find_map(RetType::cast)
+    }
+    pub fn body(&self) -> Option<BlockExpr> { 
+        self.syntax.children().find_map(BlockExpr::cast)
+    }
+    // ...
+}
+```
+
+Variants like expressions, patterns or items are modeled with `enum`s, which also implement `AstNode`:
+
+```rust
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum AssocItem {
+    FnDef(FnDef),
+    TypeAliasDef(TypeAliasDef),
+    ConstDef(ConstDef),
+}
+
+impl AstNode for AssocItem {
+    ...
+}
+```
+
+Shared AST substructures are modeled via (object safe) traits:
+
+```rust
+trait HasVisibility: AstNode {
+    fn visibility(&self) -> Option<Visibility>;
+}
+
+impl HasVisbility for FnDef {
+    fn visibility(&self) -> Option<Visibility> {
+        self.syntax.children().find_map(Visibility::cast)
+    }
+}
+```
+
+Points of note:
+
+* Like `SyntaxNode`s, AST nodes are cheap to clone pointer-sized owned values.
+* All "fields" are optional, to accomodate incomplete and/or erroneous source code.
+* It's always possible to go from an ast node to an untyped `SyntaxNode`.
+* It's possible to go in the opposite direction with a checked cast.
+* `enum`s allow modeling of arbitrary intersecting subsets of AST types.
+* Most of rust-analyzer works with the ast layer, with notable exceptions of:
+  * macro expansion, which needs access to raw tokens and works with `SyntaxNode`s
+  * some IDE-specific features like syntax highlighting are more conveniently implemented over a homogeneous `SyntaxNode` tree
+
+#### Alternative Designs
+
+##### Semantic Full AST
+
+In IntelliJ the AST layer (dubbed **P**rogram **S**tructure **I**nterface) can have semantics attached, and is usually backed by either syntax tree, indices, or metadata from compiled libraries. 
+The backend for PSI can change dynamically.
+
+### Syntax Tree Recap
+
+At its core, the syntax tree is a purely functional n-ary tree, which stores text at the leaf nodes and node "kinds" at all nodes. 
+A cursor layer is added on top, which gives owned, cheap to clone nodes with identity semantics, parent links and absolute offsets.
+An AST layer is added on top, which reifies each node `Kind` as a separate Rust type with the corresponding API. 
+
+## Parsing
+
+The (green) tree is constructed by a DFS "traversal" of the desired tree structure:
+
+```rust
+pub struct GreenNodeBuilder { ... }
+
+impl GreenNodeBuilder {
+    pub fn new() -> GreenNodeBuilder { ... }
+
+    pub fn token(&mut self, kind: SyntaxKind, text: &str) { ... }
+
+    pub fn start_node(&mut self, kind: SyntaxKind) { ... }
+    pub fn finish_node(&mut self) { ... }
+    
+    pub fn finish(self) -> GreenNode { ... }
+}
+```
+
+The parser, ultimatelly, needs to invoke the `GreenNodeBuilder`. 
+There are two principal sources of inputs for the parser:
+  * source text, which contains trivia tokens (whitespace and comments)
+  * token trees from macros, which lack trivia
+
+Additionaly, input tokens do not correspond 1-to-1 with output tokens. 
+For example, two consequtive `>` tokens might be glued, by the parser, into a single `>>`.
+
+For these reasons, the parser crate defines a callback interfaces for both input tokens and output trees.
+The explicit glue layer then bridges various gaps.
+
+The parser interface looks like this:
+
+```rust
+pub struct Token {
+    pub kind: SyntaxKind,
+    pub is_joined_to_next: bool,
+}
+
+pub trait TokenSource {
+    fn current(&self) -> Token;
+    fn lookahead_nth(&self, n: usize) -> Token;
+    fn is_keyword(&self, kw: &str) -> bool;
+
+    fn bump(&mut self);
+}
+
+pub trait TreeSink {
+    fn token(&mut self, kind: SyntaxKind, n_tokens: u8);
+
+    fn start_node(&mut self, kind: SyntaxKind);
+    fn finish_node(&mut self);
+
+    fn error(&mut self, error: ParseError);
+}
+
+pub fn parse(
+    token_source: &mut dyn TokenSource, 
+    tree_sink: &mut dyn TreeSink,
+) { ... }
+```
+
+Points of note:
+
+* The parser and the syntax tree are independent, they live in different crates neither of which depends on the other.
+* The parser doesn't know anything about textual contents of the tokens, with an isolated hack for checking contextual keywords.
+* For gluing tokens, the `TreeSink::token` might advance further than one atomic token ahead.
+
+### Reporting Syntax Errors
+
+Syntax errors are not stored directly in the tree.
+The primary motivation for this is that syntax tree is not necessary produced by the parser, it may also be assembled manually from pieces (which happens all the time in refactorings).
+Instead, parser reports errors to an error sink, which stores them in a `Vec`.
+If possible, errors are not reported during parsing and are postponed for a separate validation step.
+For example, parser accepts visibility modifiers on trait methods, but then a separate tree traversal flags all such visibilites as erroneous. 
+
+### Macros
+
+The primary difficulty with macros is that individual tokens have identities, which need to be preserved in the syntax tree for hygiene purposes. 
+This is handled by the `TreeSink` layer.
+Specifically, `TreeSink` constructs the tree in lockstep with draining the original token stream.
+In the process, it records which tokens of the tree correspond to which tokens of the input, by using text ranges to identify syntax tokens. 
+The end result is that parsing an expanded code yields a syntax tree and a mapping of text-ranges of the tree to original tokens.
+
+To deal with precedence in cases like `$expr * 1`, we use special invisible parenthesis, which are explicitelly handled by the parser
+
+### Whitespace & Comments
+
+Parser does not see whitespace nodes. 
+Instead, they are attached to the tree in the `TreeSink` layer.
+
+For example, in
+
+```rust
+// non doc comment
+fn foo() {}
+```
+
+the comment will be (heuristically) made a child of function node.
+
+### Incremental Reparse
+
+Green trees are cheap to modify, so incremental reparse works by patching a previous tree, without maintaining any additional state.
+The reparse is based on heuristic: we try to contain a change to a single `{}` block, and reparse only this block.
+To do this, we maintain the invariant that, even for invalid code, curly braces are always paired correctly. 
+
+In practice, incremental reparsing doesn't actually matter much for IDE use-cases, parsing from scratch seems to be fast enough.
+
+### Parsing Algorithm
+
+We use a boring hand-crafted recursive descent + pratt combination, with a special effort of continuting the parsing if an error is detected.
+
+### Parser Recap
+
+Parser itself defines traits for token sequence input and syntax tree output.
+It doesn't care about where the tokens come from, and how the resulting syntax tree looks like.
diff --git a/docs/user/assists.md b/docs/user/assists.md
index ecf206f71..c36c5df6a 100644
--- a/docs/user/assists.md
+++ b/docs/user/assists.md
@@ -209,6 +209,24 @@ fn main() {
 }
 ```
 
+## `auto_import`
+
+If the name is unresolved, provides all possible imports for it.
+
+```rust
+// BEFORE
+fn main() {
+    let map = HashMap┃::new();
+}
+
+// AFTER
+use std::collections::HashMap;
+
+fn main() {
+    let map = HashMap┃::new();
+}
+```
+
 ## `change_visibility`
 
 Adds or changes existing visibility specifier.
diff --git a/editors/code/package-lock.json b/editors/code/package-lock.json
index 05c57c7ff..b81cf3820 100644
--- a/editors/code/package-lock.json
+++ b/editors/code/package-lock.json
@@ -889,25 +889,25 @@
             }
         },
         "vscode-jsonrpc": {
-            "version": "5.0.0",
-            "resolved": "https://registry.npmjs.org/vscode-jsonrpc/-/vscode-jsonrpc-5.0.0.tgz",
-            "integrity": "sha512-QeAniC/xTWauVQgyNgEqNJ0Qm/Jw8QySGRQhRFPwb8c4FPp9k6QNgJp0ayXWws5qhdaHkiXkGPlzjOPZFQQKLw=="
+            "version": "5.0.1",
+            "resolved": "https://registry.npmjs.org/vscode-jsonrpc/-/vscode-jsonrpc-5.0.1.tgz",
+            "integrity": "sha512-JvONPptw3GAQGXlVV2utDcHx0BiY34FupW/kI6mZ5x06ER5DdPG/tXWMVHjTNULF5uKPOUUD0SaXg5QaubJL0A=="
         },
         "vscode-languageclient": {
-            "version": "6.0.0",
-            "resolved": "https://registry.npmjs.org/vscode-languageclient/-/vscode-languageclient-6.0.0.tgz",
-            "integrity": "sha512-6MDksAP79GRbcHFsXS6ndo12s0m/h7eNdS/IanRgWxaezqB4a4KzHIHrE0bE+nSFB+snaSToGs1bxnPeKdO5fQ==",
+            "version": "6.0.1",
+            "resolved": "https://registry.npmjs.org/vscode-languageclient/-/vscode-languageclient-6.0.1.tgz",
+            "integrity": "sha512-7yZaSHichTJEyOJykI2RLQEECf9MqNLoklzC/1OVi/M8ioIsWQ1+lkN1nTsUhd6+F7p9ar9dNmPiEhL0i5uUBA==",
             "requires": {
                 "semver": "^6.3.0",
-                "vscode-languageserver-protocol": "^3.15.0"
+                "vscode-languageserver-protocol": "^3.15.1"
             }
         },
         "vscode-languageserver-protocol": {
-            "version": "3.15.0",
-            "resolved": "https://registry.npmjs.org/vscode-languageserver-protocol/-/vscode-languageserver-protocol-3.15.0.tgz",
-            "integrity": "sha512-PZEopQzHR3Lo422HeDxCpGN0sYz+kReO+du3F/AcFT1cCPunoVsDJv7ikEolFRKEn+hEIZiAaIX4yoSZ+ip5Nw==",
+            "version": "3.15.1",
+            "resolved": "https://registry.npmjs.org/vscode-languageserver-protocol/-/vscode-languageserver-protocol-3.15.1.tgz",
+            "integrity": "sha512-wJAo06VM9ZBnRqslplDjfz6Tdive0O7z44yNxBFA3x0/YZkXBIL6I+9rwQ/9Y//0X0eCh12FQrj+KmEXf2L5eA==",
             "requires": {
-                "vscode-jsonrpc": "^5.0.0",
+                "vscode-jsonrpc": "^5.0.1",
                 "vscode-languageserver-types": "3.15.0"
             }
         },
diff --git a/editors/code/package.json b/editors/code/package.json
index d4c310734..cd9c99b35 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -25,7 +25,7 @@
     "dependencies": {
         "jsonc-parser": "^2.1.0",
         "seedrandom": "^3.0.5",
-        "vscode-languageclient": "^6.0.0"
+        "vscode-languageclient": "^6.0.1"
     },
     "devDependencies": {
         "@rollup/plugin-commonjs": "^11.0.0",