94 files changed, 2595 insertions, 1486 deletions

diff --git a/.travis.yml b/.travis.yml
index 04bb3be37..86bce93d6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,6 +10,7 @@ build: &rust_build
     script:
         - cargo gen-tests --verify
         - cargo gen-syntax --verify
+        - cargo test --no-run  # let's measure compile time separately
         - cargo test
     env:
         - RUSTFLAGS="-D warnings", CARGO_INCREMENTAL=0
@@ -25,7 +26,7 @@ matrix:
               - cd editors/code && npm ci && npm run travis
 
         - os: windows
-          if: branch = master
+          if: branch = master AND type = push
           before_script:
               - dos2unix ./crates/ra_syntax/tests/data/parser/**/*.txt
               - dos2unix ./crates/ra_syntax/tests/data/parser/**/*.rs
diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index b326f9c71..277b29c12 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -87,7 +87,7 @@ fixes a bug in the grammar.
 
 ### `crates/ra_db`
 
-We use [salsa][https://github.com/salsa-rs/salsa] crate for incremental and
+We use the [salsa](https://github.com/salsa-rs/salsa) crate for incremental and
 on-demand computation. Roughly, you can think of salsa as a key-value store, but
 it also can compute derived values using specified functions. The `ra_db` crate
 provides a basic infrastructure for interacting with salsa. Crucially, it
diff --git a/Cargo.lock b/Cargo.lock
index 5f82e92f4..dbadfc64e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -32,7 +32,7 @@ name = "atty"
 version = "0.2.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
  "termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -50,8 +50,8 @@ dependencies = [
  "autocfg 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "backtrace-sys 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc-demangle 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-demangle 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -61,7 +61,7 @@ version = "0.1.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.28 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -170,8 +170,8 @@ version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crossbeam-utils 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -270,16 +270,16 @@ dependencies = [
 
 [[package]]
 name = "failure"
-version = "0.1.4"
+version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "backtrace 0.3.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "failure_derive 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "failure_derive"
-version = "0.1.4"
+version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -337,7 +337,7 @@ name = "gen_lsp_server"
 version = "0.1.0"
 dependencies = [
  "crossbeam-channel 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "failure 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "languageserver-types 0.53.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.84 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -371,11 +371,6 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
-name = "id-arena"
-version = "2.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
 name = "idna"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -439,7 +434,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "libc"
-version = "0.2.45"
+version = "0.2.46"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -475,7 +470,7 @@ version = "2.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
  "version_check 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -484,7 +479,7 @@ name = "memmap"
 version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -527,7 +522,7 @@ name = "num_cpus"
 version = "1.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -540,16 +535,7 @@ dependencies = [
 
 [[package]]
 name = "parking_lot"
-version = "0.6.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "lock_api 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "parking_lot"
-version = "0.7.0"
+version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lock_api 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -558,23 +544,11 @@ dependencies = [
 
 [[package]]
 name = "parking_lot_core"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "smallvec 0.6.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "parking_lot_core"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -669,7 +643,7 @@ dependencies = [
  "fst 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_db 0.1.0",
  "ra_editor 0.1.0",
  "ra_hir 0.1.0",
@@ -678,16 +652,21 @@ dependencies = [
  "rayon 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "relative-path 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "salsa 0.9.0 (git+https://github.com/matklad/salsa.git?branch=transitive-untracked)",
+ "salsa 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
+ "unicase 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
+name = "ra_arena"
+version = "0.1.0"
+
+[[package]]
 name = "ra_cli"
 version = "0.1.0"
 dependencies = [
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "failure 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "join_to_string 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_editor 0.1.0",
  "ra_syntax 0.1.0",
@@ -698,12 +677,12 @@ dependencies = [
 name = "ra_db"
 version = "0.1.0"
 dependencies = [
- "parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_editor 0.1.0",
  "ra_syntax 0.1.0",
  "relative-path 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "salsa 0.9.0 (git+https://github.com/matklad/salsa.git?branch=transitive-untracked)",
+ "salsa 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
 ]
 
@@ -728,15 +707,15 @@ dependencies = [
  "arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "ena 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "flexi_logger 0.10.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "id-arena 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ra_arena 0.1.0",
  "ra_db 0.1.0",
  "ra_editor 0.1.0",
  "ra_syntax 0.1.0",
  "relative-path 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "salsa 0.9.0 (git+https://github.com/matklad/salsa.git?branch=transitive-untracked)",
+ "salsa 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
 ]
 
@@ -747,14 +726,14 @@ dependencies = [
  "cargo_metadata 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "crossbeam-channel 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "drop_bomb 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "failure 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "failure_derive 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "flexi_logger 0.10.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "gen_lsp_server 0.1.0",
  "im 12.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "languageserver-types 0.53.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_analysis 0.1.0",
  "ra_editor 0.1.0",
  "ra_syntax 0.1.0",
@@ -783,9 +762,9 @@ dependencies = [
  "arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "drop_bomb 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_text_edit 0.1.0",
- "rowan 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rowan 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
  "text_unit 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -807,6 +786,7 @@ version = "0.1.0"
 dependencies = [
  "crossbeam-channel 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ra_arena 0.1.0",
  "relative-path 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "tempfile 3.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -821,36 +801,35 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "rand"
-version = "0.6.1"
+version = "0.6.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_chacha 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "autocfg 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_chacha 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_hc 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_isaac 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_os 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_pcg 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_xorshift 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_xorshift 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "rand_chacha"
-version = "0.1.0"
+version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
+ "autocfg 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -883,6 +862,18 @@ dependencies = [
 ]
 
 [[package]]
+name = "rand_os"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "rand_pcg"
 version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -893,7 +884,7 @@ dependencies = [
 
 [[package]]
 name = "rand_xorshift"
-version = "0.1.0"
+version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -916,7 +907,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crossbeam-deque 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -978,17 +969,17 @@ dependencies = [
 
 [[package]]
 name = "rowan"
-version = "0.1.3"
+version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "parking_lot 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "smol_str 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "text_unit 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "rustc-demangle"
-version = "0.1.11"
+version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -1030,14 +1021,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "salsa"
-version = "0.9.0"
-source = "git+https://github.com/matklad/salsa.git?branch=transitive-untracked#a2198f1f8a1d09894b842035a1af6b0b4c133c93"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "derive-new 0.5.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "lock_api 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1174,8 +1165,8 @@ version = "3.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.50 (registry+https://github.com/rust-lang/crates.io-index)",
  "remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1206,7 +1197,7 @@ name = "teraron"
 version = "0.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "failure 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ron 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "tera 0.11.20 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1217,7 +1208,7 @@ name = "termion"
 version = "1.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.50 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_termios 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1278,7 +1269,7 @@ name = "time"
 version = "0.1.41"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.50 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1288,7 +1279,7 @@ name = "tools"
 version = "0.1.0"
 dependencies = [
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "failure 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "teraron 0.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1354,6 +1345,14 @@ dependencies = [
 ]
 
 [[package]]
+name = "unicase"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "version_check 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "unicode-bidi"
 version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1433,7 +1432,7 @@ name = "wait-timeout"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1508,8 +1507,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum either 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3be565ca5c557d7f59e7cfcf1844f9e3033650c929c6566f511e8005f205c1d0"
 "checksum ena 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f56c93cc076508c549d9bb747f79aa9b4eb098be7b8cad8830c3137ef52d1e00"
 "checksum error-chain 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "07e791d3be96241c77c43846b665ef1384606da2cd2a48730abe606a12906e02"
-"checksum failure 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "e945b93ec214c6e97b520ec6c5d80267fc97af327658ee5b9f35984626e51fbf"
-"checksum failure_derive 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "7c395a14ab27b42704e85bf2435c5c51f334ad7a96e16fe23c6e63a1cad6cc12"
+"checksum failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "795bd83d3abeb9220f257e597aa0080a508b27533824adf336529648f6abf7e2"
+"checksum failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "ea1063915fd7ef4309e222a5a07cf9c319fb9c7836b1f89b85458672dbb127e1"
 "checksum fake-simd 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "e88a8acf291dafb59c2d96e8f59828f3838bb1a70398823ade51a84de6a6deed"
 "checksum flexi_logger 0.10.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4dda06444ccc8b0a6da19d939989b4a4e83f328710ada449eedaed48c8b903cd"
 "checksum fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
@@ -1520,7 +1519,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "8be18de09a56b60ed0edf84bc9df007e30040691af7acd1c41874faac5895bfb"
 "checksum heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "20564e78d53d2bb135c343b3f47714a56af2061f1c928fdb541dc7b9fdd94205"
 "checksum humansize 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b6cab2627acfc432780848602f3f558f7e9dd427352224b0d9324025796d2a5e"
-"checksum id-arena 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3a7250033feafee46a1cecd2c2616a64aec1d064f38c9ae2bdd297728542843e"
 "checksum idna 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "38f09e0f0b1fb55fdee1f17470ad800da77af5186a1a76c026b679358b7e844e"
 "checksum im 12.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ae9c7f9bb8aee47fc16d535a705f7867a9fc83bb822e5e1043bb98e77ffeed3c"
 "checksum indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7e81a7c05f79578dbc15793d8b619db9ba32b4577003ef3af1a91c416798c58d"
@@ -1529,7 +1527,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum join_to_string 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7bddc885f3fd69dd4b5d747c2efe6dd2c36d795ea9938281ed50910e32c95e31"
 "checksum languageserver-types 0.53.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7c01845f71b8b3b3557a8179af4434a4b2570829da12371f05272d28183a06ce"
 "checksum lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a374c89b9db55895453a74c1e38861d9deec0b01b405a82516e9d5de4820dea1"
-"checksum libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)" = "2d2857ec59fadc0773853c664d2d18e7198e83883e7060b63c924cb077bd5c74"
+"checksum libc 0.2.46 (registry+https://github.com/rust-lang/crates.io-index)" = "023a4cd09b2ff695f9734c1934145a315594b7986398496841c7031a5a1bbdbd"
 "checksum lock_api 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "62ebf1391f6acad60e5c8b43706dde4582df75c06698ab44511d15016bc2442c"
 "checksum log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c84ec4b527950aa83a329754b01dbe3f58361d1c5efacd1f6d68c494d08a17c6"
 "checksum maplit 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "08cbb6b4fef96b6d77bfc40ec491b1690c779e77b05cd9f07f787ed376fd4c43"
@@ -1543,9 +1541,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "0b3a5d7cc97d6d30d8b9bc8fa19bf45349ffe46241e8816f50f62f6d6aaabee1"
 "checksum num_cpus 1.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5a69d464bdc213aaaff628444e99578ede64e9c854025aa43b9796530afa9238"
 "checksum owning_ref 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "49a4b8ea2179e6a2e27411d3bca09ca6dd630821cf6894c6c7c8467a8ee7ef13"
-"checksum parking_lot 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)" = "f0802bff09003b291ba756dc7e79313e51cc31667e94afbe847def490424cde5"
-"checksum parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9723236a9525c757d9725b993511e3fc941e33f27751942232f0058298297edf"
-"checksum parking_lot_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ad7f7e6ebdc79edff6fdcb87a55b620174f7a989e3eb31b65231f4af57f00b8c"
+"checksum parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ab41b4aed082705d1056416ae4468b6ea99d52599ecf3169b00088d43113e337"
 "checksum parking_lot_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "94c8c7923936b28d546dfd14d4472eaf34c99b14e1c973a32b3e6d4eb04298c9"
 "checksum percent-encoding 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "31010dd2e1ac33d5b46a5b413495239882813e0369f8ed8a5e266f173602f831"
 "checksum pest 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "54f0c72a98d8ab3c99560bfd16df8059cc10e1f9a8e83e6e3b97718dd766e9c3"
@@ -1557,14 +1553,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum quick-error 1.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9274b940887ce9addde99c4eee6b5c44cc494b182b97e73dc8ffdcb3397fd3f0"
 "checksum quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)" = "53fa22a1994bd0f9372d7a816207d8a2677ad0325b073f5c5332760f0fb62b5c"
 "checksum rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e464cd887e869cddcae8792a4ee31d23c7edd516700695608f5b98c67ee0131c"
-"checksum rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ae9d223d52ae411a33cf7e54ec6034ec165df296ccd23533d671a28252b6f66a"
-"checksum rand_chacha 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "771b009e3a508cb67e8823dda454aaa5368c7bc1c16829fb77d3e980440dd34a"
+"checksum rand 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)" = "b65e163105a6284f841bd23100a015895f54340e88a5ffc9ca7b8b33827cfce0"
+"checksum rand_chacha 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "556d3a1ca6600bfcbab7c7c91ccb085ac7fbbcd70e008a98742e7847f4f7bcef"
 "checksum rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "1961a422c4d189dfb50ffa9320bf1f2a9bd54ecb92792fb9477f99a1045f3372"
 "checksum rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0905b6b7079ec73b314d4c748701f6931eb79fd97c668caa3f1899b22b32c6db"
 "checksum rand_hc 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7b40677c7be09ae76218dc623efbf7b18e34bced3f38883af07bb75630a21bc4"
 "checksum rand_isaac 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ded997c9d5f13925be2a6fd7e66bf1872597f759fd9dd93513dd7e92e5a5ee08"
+"checksum rand_os 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "de5ac4de1c2973e1391dc305cb0fbf8788cb58068e98255439b7485a77022273"
 "checksum rand_pcg 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "086bd09a33c7044e56bb44d5bdde5a60e7f119a9e95b0775f545de759a32fe05"
-"checksum rand_xorshift 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "effa3fcaa47e18db002bdde6060944b6d2f9cfd8db471c30e873448ad9187be3"
+"checksum rand_xorshift 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cbf7e9e623549b0e21f6e97cf8ecf247c1a8fd2e8a992ae265314300b2455d5c"
 "checksum rayon 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "373814f27745b2686b350dd261bfd24576a6fb0e2c5919b3a2b6005f820b0473"
 "checksum rayon-core 1.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b055d1e92aba6877574d8fe604a63c8b5df60f60e5982bf7ccbb1338ea527356"
 "checksum redox_syscall 0.1.50 (registry+https://github.com/rust-lang/crates.io-index)" = "52ee9a534dc1301776eff45b4fa92d2c39b1d8c3d3357e6eb593e0d795506fc2"
@@ -1574,14 +1571,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum relative-path 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0e7790c7f1cc73d831d28dc5a7deb316a006e7848e6a7f467cdb10a0a9e0fb1c"
 "checksum remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "3488ba1b9a2084d38645c4c08276a1752dcbf2c7130d74f1569681ad5d2799c5"
 "checksum ron 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c48677d8a9247a4e0d1f3f9cb4b0a8e29167fdc3c04f383a5e669cd7a960ae0f"
-"checksum rowan 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a9ccca91953e9c549cac18e8f41daa5d49dad1c9a4c9bb977ac42718bb34e1bf"
-"checksum rustc-demangle 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)" = "01b90379b8664dd83460d59bdc5dd1fd3172b8913788db483ed1325171eab2f7"
+"checksum rowan 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "c218b4430ab922850b71b14fa9bca224425097f935f6155c0b6a4b1f398a54f0"
+"checksum rustc-demangle 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "adacaae16d02b6ec37fdc7acfcddf365978de76d1983d3ee22afc260e1ca9619"
 "checksum rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7540fc8b0c49f096ee9c961cda096467dce8084bec6bdca2fc83895fd9b28cb8"
 "checksum rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
 "checksum rusty-fork 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "9591f190d2852720b679c21f66ad929f9f1d7bb09d1193c26167586029d8489c"
 "checksum ryu 0.2.7 (registry+https://github.com/rust-lang/crates.io-index)" = "eb9e9b8cde282a9fe6a42dd4681319bfb63f121b8a8ee9439c6f4107e58a46f7"
 "checksum safemem 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8dca453248a96cb0749e36ccdfe2b0b4e54a61bfef89fb97ec621eb8e0a93dd9"
-"checksum salsa 0.9.0 (git+https://github.com/matklad/salsa.git?branch=transitive-untracked)" = "<none>"
+"checksum salsa 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)" = "442ef4acdb48c0e24ddaf4f3b62555af2d1da7047f2f26acd54ae73010aa0c02"
 "checksum same-file 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "8f20c4be53a8a1ff4c1f1b2bd14570d2f634628709752f0702ecdd2b3f9a5267"
 "checksum scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "94258f53601af11e6a49f722422f6e3425c52b06245a5cf9bc09908b174f5e27"
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
@@ -1616,6 +1613,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum unic-segment 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c9ca47cbb09fb5fcd066b5867d11dc528302fa465277882797d6a836e1ee6f9e"
 "checksum unic-ucd-segment 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "48f1a08ce0409a9e391b88d1930118eec48af12742fc538bcec55f775865776e"
 "checksum unic-ucd-version 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "cf1f5e6c6c53c2d0ece4a5964bc55fcff8602153063cb4fab20958ff32998ff6"
+"checksum unicase 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9d3218ea14b4edcaccfa0df0a64a3792a2c32cc706f1b336e48867f9d3147f90"
 "checksum unicode-bidi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "49f2bd0c6468a8230e1db229cff8029217cf623c767ea5d60bfbd42729ea54d5"
 "checksum unicode-normalization 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "6a0180bc61fc5a987082bfa111f4cc95c4caff7f9799f3e46df09163a937aa25"
 "checksum unicode-segmentation 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "aa6024fc12ddfd1c6dbc14a80fa2324d4568849869b779f6bd37e5e4c03344d1"
diff --git a/Cargo.toml b/Cargo.toml
index dd8499c06..c5155e899 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,4 +6,3 @@ incremental = true
 debug = true
 
 [patch.'crates-io']
-salsa = { git = "https://github.com/matklad/salsa.git", branch = "transitive-untracked" }
diff --git a/crates/ra_analysis/Cargo.toml b/crates/ra_analysis/Cargo.toml
index c0174cdc5..11c78ced8 100644
--- a/crates/ra_analysis/Cargo.toml
+++ b/crates/ra_analysis/Cargo.toml
@@ -10,9 +10,10 @@ log = "0.4.5"
 relative-path = "0.4.0"
 rayon = "1.0.2"
 fst = "0.3.1"
-salsa = "0.9.0"
+salsa = "0.9.1"
 rustc-hash = "1.0"
 parking_lot = "0.7.0"
+unicase = "2.2.0"
 
 ra_syntax = { path = "../ra_syntax" }
 ra_editor = { path = "../ra_editor" }
diff --git a/crates/ra_analysis/src/completion/complete_dot.rs b/crates/ra_analysis/src/completion/complete_dot.rs
index f24835d17..031d8b98f 100644
--- a/crates/ra_analysis/src/completion/complete_dot.rs
+++ b/crates/ra_analysis/src/completion/complete_dot.rs
@@ -73,6 +73,21 @@ mod tests {
     }
 
     #[test]
+    fn test_struct_field_completion_self() {
+        check_ref_completion(
+            r"
+            struct A { the_field: u32 }
+            impl A {
+                fn foo(self) {
+                    self.<|>
+                }
+            }
+            ",
+            r#"the_field"#,
+        );
+    }
+
+    #[test]
     fn test_no_struct_field_completion_for_method_call() {
         check_ref_completion(
             r"
diff --git a/crates/ra_analysis/src/db.rs b/crates/ra_analysis/src/db.rs
index d7740f0c4..5422a400b 100644
--- a/crates/ra_analysis/src/db.rs
+++ b/crates/ra_analysis/src/db.rs
@@ -105,6 +105,7 @@ salsa::database_storage! {
             fn type_for_field() for hir::db::TypeForFieldQuery;
             fn struct_data() for hir::db::StructDataQuery;
             fn enum_data() for hir::db::EnumDataQuery;
+            fn impls_in_module() for hir::db::ImplsInModuleQuery;
         }
     }
 }
diff --git a/crates/ra_analysis/src/goto_defenition.rs b/crates/ra_analysis/src/goto_defenition.rs
new file mode 100644
index 000000000..607a25115
--- /dev/null
+++ b/crates/ra_analysis/src/goto_defenition.rs
@@ -0,0 +1,73 @@
+use ra_db::FileId;
+use ra_syntax::ast;
+
+use crate::db::RootDatabase;
+
+pub fn goto_defenition(db: &RootDatabase, position: FilePosition,
+) -> Cancelable<Option<Vec<NavigationTarget>>> {
+    let file = db.source_file(position.file_id);
+    let syntax = file.syntax();
+    if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(syntax, position.offset) {
+        return Ok(Some(reference_defenition(db, position.file_id, name_ref)));
+    }
+    if let Some(name) = find_node_at_offset::<ast::Name>(syntax, position.offset)  {
+        return Ok(Some(name_defenition(db, position.file_idname)));
+    }
+    Ok(None)
+}
+
+fn reference_defenition(db: &RootDatabase, file_id: FileId, name_ref: ast::NameRef) -> Cancelable<Vec<Nav>> {
+    if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(syntax, position.offset) {
+        let mut rr = ReferenceResolution::new(name_ref.syntax().range());
+        if let Some(fn_descr) =
+            source_binder::function_from_child_node(self, position.file_id, name_ref.syntax())?
+        {
+            let scope = fn_descr.scopes(self);
+            // First try to resolve the symbol locally
+            if let Some(entry) = scope.resolve_local_name(name_ref) {
+                rr.resolves_to.push(NavigationTarget {
+                    file_id: position.file_id,
+                    name: entry.name().to_string().into(),
+                    range: entry.ptr().range(),
+                    kind: NAME,
+                    ptr: None,
+                });
+                return Ok(Some(rr));
+            };
+        }
+        // If that fails try the index based approach.
+        rr.resolves_to.extend(
+            self.index_resolve(name_ref)?
+                .into_iter()
+                .map(NavigationTarget::from_symbol),
+        );
+        return Ok(Some(rr));
+    }
+        if let Some(name) = find_node_at_offset::<ast::Name>(syntax, position.offset) {
+            let mut rr = ReferenceResolution::new(name.syntax().range());
+            if let Some(module) = name.syntax().parent().and_then(ast::Module::cast) {
+                if module.has_semi() {
+                    if let Some(child_module) =
+                        source_binder::module_from_declaration(self, position.file_id, module)?
+                    {
+                        let file_id = child_module.file_id();
+                        let name = match child_module.name() {
+                            Some(name) => name.to_string().into(),
+                            None => "".into(),
+                        };
+                        let symbol = NavigationTarget {
+                            file_id,
+                            name,
+                            range: TextRange::offset_len(0.into(), 0.into()),
+                            kind: MODULE,
+                            ptr: None,
+                        };
+                        rr.resolves_to.push(symbol);
+                        return Ok(Some(rr));
+                    }
+                }
+            }
+        }
+        Ok(None)
+
+}
diff --git a/crates/ra_analysis/src/imp.rs b/crates/ra_analysis/src/imp.rs
index b812c3441..eae73c2c4 100644
--- a/crates/ra_analysis/src/imp.rs
+++ b/crates/ra_analysis/src/imp.rs
@@ -6,7 +6,7 @@ use hir::{
     self, FnSignatureInfo, Problem, source_binder,
 };
 use ra_db::{FilesDatabase, SourceRoot, SourceRootId, SyntaxDatabase};
-use ra_editor::{self, find_node_at_offset, LocalEdit, Severity};
+use ra_editor::{self, find_node_at_offset, assists, LocalEdit, Severity};
 use ra_syntax::{
     algo::{find_covering_node, visit::{visitor, Visitor}},
     ast::{self, ArgListOwner, Expr, FnDef, NameOwner},
@@ -165,9 +165,11 @@ impl db::RootDatabase {
                 };
             }
             // If that fails try the index based approach.
-            for (file_id, symbol) in self.index_resolve(name_ref)? {
-                rr.add_resolution(file_id, symbol);
-            }
+            rr.resolves_to.extend(
+                self.index_resolve(name_ref)?
+                    .into_iter()
+                    .map(NavigationTarget::from_symbol),
+            );
             return Ok(Some(rr));
         }
         if let Some(name) = find_node_at_offset::<ast::Name>(syntax, position.offset) {
@@ -333,19 +335,9 @@ impl db::RootDatabase {
 
     pub(crate) fn assists(&self, frange: FileRange) -> Vec<SourceChange> {
         let file = self.source_file(frange.file_id);
-        let offset = frange.range.start();
-        let actions = vec![
-            ra_editor::flip_comma(&file, offset).map(|f| f()),
-            ra_editor::add_derive(&file, offset).map(|f| f()),
-            ra_editor::add_impl(&file, offset).map(|f| f()),
-            ra_editor::make_pub_crate(&file, offset).map(|f| f()),
-            ra_editor::introduce_variable(&file, frange.range).map(|f| f()),
-        ];
-        actions
+        assists::assists(&file, frange.range)
             .into_iter()
-            .filter_map(|local_edit| {
-                Some(SourceChange::from_local_edit(frange.file_id, local_edit?))
-            })
+            .map(|local_edit| SourceChange::from_local_edit(frange.file_id, local_edit))
             .collect()
     }
 
@@ -362,13 +354,15 @@ impl db::RootDatabase {
 
         // Resolve the function's NameRef (NOTE: this isn't entirely accurate).
         let file_symbols = self.index_resolve(name_ref)?;
-        for (fn_file_id, fs) in file_symbols {
-            if fs.ptr.kind() == FN_DEF {
-                let fn_file = self.source_file(fn_file_id);
-                let fn_def = fs.ptr.resolve(&fn_file);
+        for symbol in file_symbols {
+            if symbol.ptr.kind() == FN_DEF {
+                let fn_file = self.source_file(symbol.file_id);
+                let fn_def = symbol.ptr.resolve(&fn_file);
                 let fn_def = ast::FnDef::cast(fn_def.borrowed()).unwrap();
                 let descr = ctry!(source_binder::function_from_source(
-                    self, fn_file_id, fn_def
+                    self,
+                    symbol.file_id,
+                    fn_def
                 )?);
                 if let Some(descriptor) = descr.signature_info(self) {
                     // If we have a calling expression let's find which argument we are on
@@ -440,7 +434,7 @@ impl db::RootDatabase {
             .map(|(file_id, text_range)| SourceFileEdit {
                 file_id: *file_id,
                 edit: {
-                    let mut builder = ra_text_edit::TextEditBuilder::new();
+                    let mut builder = ra_text_edit::TextEditBuilder::default();
                     builder.replace(*text_range, new_name.into());
                     builder.finish()
                 },
@@ -448,7 +442,7 @@ impl db::RootDatabase {
             .collect::<Vec<_>>();
         Ok(res)
     }
-    fn index_resolve(&self, name_ref: ast::NameRef) -> Cancelable<Vec<(FileId, FileSymbol)>> {
+    fn index_resolve(&self, name_ref: ast::NameRef) -> Cancelable<Vec<FileSymbol>> {
         let name = name_ref.text();
         let mut query = Query::new(name.to_string());
         query.exact();
diff --git a/crates/ra_analysis/src/lib.rs b/crates/ra_analysis/src/lib.rs
index 61af676b2..1e26a2889 100644
--- a/crates/ra_analysis/src/lib.rs
+++ b/crates/ra_analysis/src/lib.rs
@@ -237,11 +237,11 @@ pub struct NavigationTarget {
 }
 
 impl NavigationTarget {
-    fn from_symbol(file_id: FileId, symbol: FileSymbol) -> NavigationTarget {
+    fn from_symbol(symbol: FileSymbol) -> NavigationTarget {
         NavigationTarget {
+            file_id: symbol.file_id,
             name: symbol.name.clone(),
             kind: symbol.ptr.kind(),
-            file_id,
             range: symbol.ptr.range(),
             ptr: Some(symbol.ptr.clone()),
         }
@@ -278,11 +278,6 @@ impl ReferenceResolution {
             resolves_to: Vec::new(),
         }
     }
-
-    fn add_resolution(&mut self, file_id: FileId, symbol: FileSymbol) {
-        self.resolves_to
-            .push(NavigationTarget::from_symbol(file_id, symbol))
-    }
 }
 
 /// `AnalysisHost` stores the current state of the world.
@@ -380,7 +375,7 @@ impl Analysis {
     pub fn symbol_search(&self, query: Query) -> Cancelable<Vec<NavigationTarget>> {
         let res = symbol_index::world_symbols(&*self.db, query)?
             .into_iter()
-            .map(|(file_id, symbol)| NavigationTarget::from_symbol(file_id, symbol))
+            .map(NavigationTarget::from_symbol)
             .collect();
         Ok(res)
     }
@@ -399,7 +394,7 @@ impl Analysis {
     pub fn doc_text_for(&self, nav: NavigationTarget) -> Cancelable<Option<String>> {
         self.db.doc_text_for(nav)
     }
-    /// Returns a `mod name;` declaration whihc created the current module.
+    /// Returns a `mod name;` declaration which created the current module.
     pub fn parent_module(&self, position: FilePosition) -> Cancelable<Vec<NavigationTarget>> {
         self.db.parent_module(position)
     }
diff --git a/crates/ra_analysis/src/mock_analysis.rs b/crates/ra_analysis/src/mock_analysis.rs
index 960529404..846c76cfe 100644
--- a/crates/ra_analysis/src/mock_analysis.rs
+++ b/crates/ra_analysis/src/mock_analysis.rs
@@ -4,7 +4,7 @@ use relative_path::RelativePathBuf;
 use test_utils::{extract_offset, extract_range, parse_fixture, CURSOR_MARKER};
 use ra_db::mock::FileMap;
 
-use crate::{Analysis, AnalysisChange, AnalysisHost, FileId, FilePosition, FileRange, SourceRootId};
+use crate::{Analysis, AnalysisChange, AnalysisHost, CrateGraph, FileId, FilePosition, FileRange, SourceRootId};
 
 /// Mock analysis is used in test to bootstrap an AnalysisHost/Analysis
 /// from a set of in-memory files.
@@ -87,12 +87,17 @@ impl MockAnalysis {
         let source_root = SourceRootId(0);
         let mut change = AnalysisChange::new();
         change.add_root(source_root, true);
+        let mut crate_graph = CrateGraph::default();
         for (path, contents) in self.files.into_iter() {
             assert!(path.starts_with('/'));
             let path = RelativePathBuf::from_path(&path[1..]).unwrap();
             let file_id = file_map.add(path.clone());
+            if path == "/lib.rs" || path == "/main.rs" {
+                crate_graph.add_crate_root(file_id);
+            }
             change.add_file(source_root, file_id, path, Arc::new(contents));
         }
+        change.set_crate_graph(crate_graph);
         // change.set_file_resolver(Arc::new(file_map));
         host.apply_change(change);
         host
diff --git a/crates/ra_analysis/src/symbol_index.rs b/crates/ra_analysis/src/symbol_index.rs
index 10d8e8059..e2b1c88fe 100644
--- a/crates/ra_analysis/src/symbol_index.rs
+++ b/crates/ra_analysis/src/symbol_index.rs
@@ -20,6 +20,7 @@
 //! file in the current workspace, and run a query aginst the union of all
 //! thouse fsts.
 use std::{
+    cmp::Ordering,
     hash::{Hash, Hasher},
     sync::Arc,
 };
@@ -27,11 +28,11 @@ use std::{
 use fst::{self, Streamer};
 use ra_syntax::{
     SyntaxNodeRef, SourceFileNode, SmolStr,
-    algo::visit::{visitor, Visitor},
+    algo::{visit::{visitor, Visitor}, find_covering_node},
     SyntaxKind::{self, *},
     ast::{self, NameOwner},
 };
-use ra_db::{SyntaxDatabase, SourceRootId, FilesDatabase, LocalSyntaxPtr};
+use ra_db::{SourceRootId, FilesDatabase, LocalSyntaxPtr};
 use salsa::ParallelDatabase;
 use rayon::prelude::*;
 
@@ -41,7 +42,7 @@ use crate::{
 };
 
 salsa::query_group! {
-    pub(crate) trait SymbolsDatabase: SyntaxDatabase {
+    pub(crate) trait SymbolsDatabase: hir::db::HirDatabase {
         fn file_symbols(file_id: FileId) -> Cancelable<Arc<SymbolIndex>> {
             type FileSymbolsQuery;
         }
@@ -52,16 +53,26 @@ salsa::query_group! {
     }
 }
 
-fn file_symbols(db: &impl SyntaxDatabase, file_id: FileId) -> Cancelable<Arc<SymbolIndex>> {
+fn file_symbols(db: &impl SymbolsDatabase, file_id: FileId) -> Cancelable<Arc<SymbolIndex>> {
     db.check_canceled()?;
-    let syntax = db.source_file(file_id);
-    Ok(Arc::new(SymbolIndex::for_file(file_id, syntax)))
+    let source_file = db.source_file(file_id);
+    let mut symbols = source_file
+        .syntax()
+        .descendants()
+        .filter_map(to_symbol)
+        .map(move |(name, ptr)| FileSymbol { name, ptr, file_id })
+        .collect::<Vec<_>>();
+
+    for (name, text_range) in hir::source_binder::macro_symbols(db, file_id)? {
+        let node = find_covering_node(source_file.syntax(), text_range);
+        let ptr = LocalSyntaxPtr::new(node);
+        symbols.push(FileSymbol { file_id, name, ptr })
+    }
+
+    Ok(Arc::new(SymbolIndex::new(symbols)))
 }
 
-pub(crate) fn world_symbols(
-    db: &RootDatabase,
-    query: Query,
-) -> Cancelable<Vec<(FileId, FileSymbol)>> {
+pub(crate) fn world_symbols(db: &RootDatabase, query: Query) -> Cancelable<Vec<FileSymbol>> {
     /// Need to wrap Snapshot to provide `Clone` impl for `map_with`
     struct Snap(salsa::Snapshot<RootDatabase>);
     impl Clone for Snap {
@@ -95,7 +106,7 @@ pub(crate) fn world_symbols(
 
 #[derive(Default, Debug)]
 pub(crate) struct SymbolIndex {
-    symbols: Vec<(FileId, FileSymbol)>,
+    symbols: Vec<FileSymbol>,
     map: fst::Map,
 }
 
@@ -114,6 +125,17 @@ impl Hash for SymbolIndex {
 }
 
 impl SymbolIndex {
+    fn new(mut symbols: Vec<FileSymbol>) -> SymbolIndex {
+        fn cmp(s1: &FileSymbol, s2: &FileSymbol) -> Ordering {
+            unicase::Ascii::new(s1.name.as_str()).cmp(&unicase::Ascii::new(s2.name.as_str()))
+        }
+        symbols.par_sort_by(cmp);
+        symbols.dedup_by(|s1, s2| cmp(s1, s2) == Ordering::Equal);
+        let names = symbols.iter().map(|it| it.name.as_str().to_lowercase());
+        let map = fst::Map::from_iter(names.into_iter().zip(0u64..)).unwrap();
+        SymbolIndex { symbols, map }
+    }
+
     pub(crate) fn len(&self) -> usize {
         self.symbols.len()
     }
@@ -121,30 +143,21 @@ impl SymbolIndex {
     pub(crate) fn for_files(
         files: impl ParallelIterator<Item = (FileId, SourceFileNode)>,
     ) -> SymbolIndex {
-        let mut symbols = files
+        let symbols = files
             .flat_map(|(file_id, file)| {
                 file.syntax()
                     .descendants()
                     .filter_map(to_symbol)
-                    .map(move |symbol| (symbol.name.as_str().to_lowercase(), (file_id, symbol)))
+                    .map(move |(name, ptr)| FileSymbol { name, ptr, file_id })
                     .collect::<Vec<_>>()
             })
             .collect::<Vec<_>>();
-        symbols.par_sort_by(|s1, s2| s1.0.cmp(&s2.0));
-        symbols.dedup_by(|s1, s2| s1.0 == s2.0);
-        let (names, symbols): (Vec<String>, Vec<(FileId, FileSymbol)>) =
-            symbols.into_iter().unzip();
-        let map = fst::Map::from_iter(names.into_iter().zip(0u64..)).unwrap();
-        SymbolIndex { symbols, map }
-    }
-
-    pub(crate) fn for_file(file_id: FileId, file: SourceFileNode) -> SymbolIndex {
-        SymbolIndex::for_files(rayon::iter::once((file_id, file)))
+        SymbolIndex::new(symbols)
     }
 }
 
 impl Query {
-    pub(crate) fn search(self, indices: &[Arc<SymbolIndex>]) -> Vec<(FileId, FileSymbol)> {
+    pub(crate) fn search(self, indices: &[Arc<SymbolIndex>]) -> Vec<FileSymbol> {
         let mut op = fst::map::OpBuilder::new();
         for file_symbols in indices.iter() {
             let automaton = fst::automaton::Subsequence::new(&self.lowercased);
@@ -160,14 +173,14 @@ impl Query {
                 let file_symbols = &indices[indexed_value.index];
                 let idx = indexed_value.value as usize;
 
-                let (file_id, symbol) = &file_symbols.symbols[idx];
+                let symbol = &file_symbols.symbols[idx];
                 if self.only_types && !is_type(symbol.ptr.kind()) {
                     continue;
                 }
                 if self.exact && symbol.name != self.query {
                     continue;
                 }
-                res.push((*file_id, symbol.clone()));
+                res.push(symbol.clone());
             }
         }
         res
@@ -185,17 +198,16 @@ fn is_type(kind: SyntaxKind) -> bool {
 /// possible.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub(crate) struct FileSymbol {
+    pub(crate) file_id: FileId,
     pub(crate) name: SmolStr,
     pub(crate) ptr: LocalSyntaxPtr,
 }
 
-fn to_symbol(node: SyntaxNodeRef) -> Option<FileSymbol> {
-    fn decl<'a, N: NameOwner<'a>>(node: N) -> Option<FileSymbol> {
-        let name = node.name()?;
-        Some(FileSymbol {
-            name: name.text(),
-            ptr: LocalSyntaxPtr::new(node.syntax()),
-        })
+fn to_symbol(node: SyntaxNodeRef) -> Option<(SmolStr, LocalSyntaxPtr)> {
+    fn decl<'a, N: NameOwner<'a>>(node: N) -> Option<(SmolStr, LocalSyntaxPtr)> {
+        let name = node.name()?.text();
+        let ptr = LocalSyntaxPtr::new(node.syntax());
+        Some((name, ptr))
     }
     visitor()
         .visit(decl::<ast::FnDef>)
diff --git a/crates/ra_analysis/src/syntax_highlighting.rs b/crates/ra_analysis/src/syntax_highlighting.rs
index ccea4aee3..35e153ca0 100644
--- a/crates/ra_analysis/src/syntax_highlighting.rs
+++ b/crates/ra_analysis/src/syntax_highlighting.rs
@@ -43,6 +43,7 @@ mod tests {
             "
             fn main() {
                 ctry!({ let x = 92; x});
+                vec![{ let x = 92; x}];
             }
             ",
         );
@@ -53,10 +54,17 @@ mod tests {
                 HighlightedRange { range: [41; 46), tag: "macro" },
                 HighlightedRange { range: [49; 52), tag: "keyword" },
                 HighlightedRange { range: [57; 59), tag: "literal" },
+                HighlightedRange { range: [82; 86), tag: "macro" },
+                HighlightedRange { range: [89; 92), tag: "keyword" },
+                HighlightedRange { range: [97; 99), tag: "literal" },
                 HighlightedRange { range: [49; 52), tag: "keyword" },
                 HighlightedRange { range: [53; 54), tag: "function" },
                 HighlightedRange { range: [57; 59), tag: "literal" },
-                HighlightedRange { range: [61; 62), tag: "text" }]"#,
+                HighlightedRange { range: [61; 62), tag: "text" },
+                HighlightedRange { range: [89; 92), tag: "keyword" },
+                HighlightedRange { range: [93; 94), tag: "function" },
+                HighlightedRange { range: [97; 99), tag: "literal" },
+                HighlightedRange { range: [101; 102), tag: "text" }]"#,
             &highlights,
         )
     }
diff --git a/crates/ra_analysis/tests/tests.rs b/crates/ra_analysis/tests/test/main.rs
index bcf29d29c..beeae1e19 100644
--- a/crates/ra_analysis/tests/tests.rs
+++ b/crates/ra_analysis/tests/test/main.rs
@@ -1,9 +1,12 @@
+mod runnables;
+mod type_of;
+
 use ra_syntax::TextRange;
 use test_utils::{assert_eq_dbg, assert_eq_text};
 
 use ra_analysis::{
     mock_analysis::{analysis_and_position, single_file, single_file_with_position, MockAnalysis},
-    AnalysisChange, CrateGraph, FileId, FnSignatureInfo,
+    AnalysisChange, CrateGraph, FileId, FnSignatureInfo, Query
 };
 
 fn get_signature(text: &str) -> (FnSignatureInfo, Option<usize>) {
@@ -135,14 +138,14 @@ fn test_resolve_parent_module_for_inline() {
 fn test_resolve_crate_root() {
     let mock = MockAnalysis::with_files(
         "
-        //- /lib.rs
+        //- /bar.rs
         mod foo;
-        //- /foo.rs
+        //- /bar/foo.rs
         // emtpy <|>
     ",
     );
-    let root_file = mock.id_of("/lib.rs");
-    let mod_file = mock.id_of("/foo.rs");
+    let root_file = mock.id_of("/bar.rs");
+    let mod_file = mock.id_of("/bar/foo.rs");
     let mut host = mock.analysis_host();
     assert!(host.analysis().crate_for(mod_file).unwrap().is_empty());
 
@@ -246,7 +249,8 @@ fn bar() {
 fn test_fn_signature_with_docs_simple() {
     let (desc, param) = get_signature(
         r#"
-// test
+/// test
+// non-doc-comment
 fn foo(j: u32) -> u32 {
     j
 }
@@ -528,10 +532,11 @@ fn test_rename_for_mut_param() {
     }"#,
     );
 }
+
 fn test_rename(text: &str, new_name: &str, expected: &str) {
     let (analysis, position) = single_file_with_position(text);
     let edits = analysis.rename(position, new_name).unwrap();
-    let mut text_edit_bulder = ra_text_edit::TextEditBuilder::new();
+    let mut text_edit_bulder = ra_text_edit::TextEditBuilder::default();
     let mut file_id: Option<FileId> = None;
     for edit in edits {
         file_id = Some(edit.file_id);
@@ -544,3 +549,19 @@ fn test_rename(text: &str, new_name: &str, expected: &str) {
         .apply(&*analysis.file_text(file_id.unwrap()));
     assert_eq_text!(expected, &*result);
 }
+
+#[test]
+fn world_symbols_include_stuff_from_macros() {
+    let (analysis, _) = single_file(
+        "
+salsa::query_group! {
+pub trait HirDatabase: SyntaxDatabase {}
+}
+    ",
+    );
+
+    let mut symbols = analysis.symbol_search(Query::new("Hir".into())).unwrap();
+    let s = symbols.pop().unwrap();
+    assert_eq!(s.name(), "HirDatabase");
+    assert_eq!(s.range(), TextRange::from_to(33.into(), 44.into()));
+}
diff --git a/crates/ra_analysis/tests/runnables.rs b/crates/ra_analysis/tests/test/runnables.rs
index 9e5342c46..e6e0afbc3 100644
--- a/crates/ra_analysis/tests/runnables.rs
+++ b/crates/ra_analysis/tests/test/runnables.rs
@@ -1,15 +1,6 @@
-extern crate ra_analysis;
-extern crate ra_editor;
-extern crate ra_syntax;
-extern crate relative_path;
-extern crate rustc_hash;
-extern crate test_utils;
-
 use test_utils::assert_eq_dbg;
 
-use ra_analysis::{
-    mock_analysis::{analysis_and_position},
-};
+use ra_analysis::mock_analysis::analysis_and_position;
 
 #[test]
 fn test_runnables() {
diff --git a/crates/ra_analysis/tests/type_of.rs b/crates/ra_analysis/tests/test/type_of.rs
index 375f808bb..9d15b52a8 100644
--- a/crates/ra_analysis/tests/type_of.rs
+++ b/crates/ra_analysis/tests/test/type_of.rs
@@ -1,6 +1,4 @@
-use ra_analysis::{
-    mock_analysis::{single_file_with_range},
-};
+use ra_analysis::mock_analysis::single_file_with_range;
 
 #[test]
 fn test_type_of_for_function() {
diff --git a/crates/ra_arena/Cargo.toml b/crates/ra_arena/Cargo.toml
new file mode 100644
index 000000000..9594e2d0f
--- /dev/null
+++ b/crates/ra_arena/Cargo.toml
@@ -0,0 +1,5 @@
+[package]
+edition = "2018"
+name = "ra_arena"
+version = "0.1.0"
+authors = ["Aleksey Kladov <[email protected]>"]
diff --git a/crates/ra_arena/src/lib.rs b/crates/ra_arena/src/lib.rs
new file mode 100644
index 000000000..a5eeb4118
--- /dev/null
+++ b/crates/ra_arena/src/lib.rs
@@ -0,0 +1,97 @@
+//! Yet another index-based arena.
+
+use std::{
+    fmt,
+    marker::PhantomData,
+    ops::{Index, IndexMut},
+};
+
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct RawId(u32);
+
+impl From<RawId> for u32 {
+    fn from(raw: RawId) -> u32 {
+        raw.0
+    }
+}
+
+impl From<u32> for RawId {
+    fn from(id: u32) -> RawId {
+        RawId(id)
+    }
+}
+
+impl fmt::Debug for RawId {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl fmt::Display for RawId {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Arena<ID: ArenaId, T> {
+    data: Vec<T>,
+    _ty: PhantomData<ID>,
+}
+
+#[macro_export]
+macro_rules! impl_arena_id {
+    ($name:ident) => {
+        impl $crate::ArenaId for $name {
+            fn from_raw(raw: $crate::RawId) -> Self {
+                $name(raw)
+            }
+            fn into_raw(self) -> $crate::RawId {
+                self.0
+            }
+        }
+    };
+}
+
+pub trait ArenaId {
+    fn from_raw(raw: RawId) -> Self;
+    fn into_raw(self) -> RawId;
+}
+
+impl<ID: ArenaId, T> Arena<ID, T> {
+    pub fn alloc(&mut self, value: T) -> ID {
+        let id = RawId(self.data.len() as u32);
+        self.data.push(value);
+        ID::from_raw(id)
+    }
+    pub fn iter<'a>(&'a self) -> impl Iterator<Item = (ID, &'a T)> {
+        self.data
+            .iter()
+            .enumerate()
+            .map(|(idx, value)| (ID::from_raw(RawId(idx as u32)), value))
+    }
+}
+
+impl<ID: ArenaId, T> Default for Arena<ID, T> {
+    fn default() -> Arena<ID, T> {
+        Arena {
+            data: Vec::new(),
+            _ty: PhantomData,
+        }
+    }
+}
+
+impl<ID: ArenaId, T> Index<ID> for Arena<ID, T> {
+    type Output = T;
+    fn index(&self, idx: ID) -> &T {
+        let idx = idx.into_raw().0 as usize;
+        &self.data[idx]
+    }
+}
+
+impl<ID: ArenaId, T> IndexMut<ID> for Arena<ID, T> {
+    fn index_mut(&mut self, idx: ID) -> &mut T {
+        let idx = idx.into_raw().0 as usize;
+        &mut self.data[idx]
+    }
+}
diff --git a/crates/ra_db/Cargo.toml b/crates/ra_db/Cargo.toml
index ecc56d953..c0e83a140 100644
--- a/crates/ra_db/Cargo.toml
+++ b/crates/ra_db/Cargo.toml
@@ -6,7 +6,7 @@ authors = ["Aleksey Kladov <[email protected]>"]
 
 [dependencies]
 relative-path = "0.4.0"
-salsa = "0.9.0"
+salsa = "0.9.1"
 rustc-hash = "1.0"
 parking_lot = "0.7.0"
 ra_syntax = { path = "../ra_syntax" }
diff --git a/crates/ra_editor/src/assists.rs b/crates/ra_editor/src/assists.rs
new file mode 100644
index 000000000..57b78342a
--- /dev/null
+++ b/crates/ra_editor/src/assists.rs
@@ -0,0 +1,188 @@
+//! This modules contains various "assits": suggestions for source code edits
+//! which are likely to occur at a given cursor positon. For example, if the
+//! cursor is on the `,`, a possible assist is swapping the elments around the
+//! comma.
+
+mod flip_comma;
+mod add_derive;
+mod add_impl;
+mod introduce_variable;
+mod change_visibility;
+mod split_import;
+
+use ra_text_edit::{TextEdit, TextEditBuilder};
+use ra_syntax::{
+    Direction, SyntaxNodeRef, TextUnit, TextRange,SourceFileNode, AstNode,
+    algo::{find_leaf_at_offset, find_covering_node, LeafAtOffset},
+};
+
+use crate::find_node_at_offset;
+
+pub use self::{
+    flip_comma::flip_comma,
+    add_derive::add_derive,
+    add_impl::add_impl,
+    introduce_variable::introduce_variable,
+    change_visibility::change_visibility,
+    split_import::split_import,
+};
+
+/// Return all the assists applicable at the given position.
+pub fn assists(file: &SourceFileNode, range: TextRange) -> Vec<LocalEdit> {
+    let ctx = AssistCtx::new(file, range);
+    [
+        flip_comma,
+        add_derive,
+        add_impl,
+        introduce_variable,
+        change_visibility,
+        split_import,
+    ]
+    .iter()
+    .filter_map(|&assist| ctx.clone().apply(assist))
+    .collect()
+}
+
+#[derive(Debug)]
+pub struct LocalEdit {
+    pub label: String,
+    pub edit: TextEdit,
+    pub cursor_position: Option<TextUnit>,
+}
+
+fn non_trivia_sibling(node: SyntaxNodeRef, direction: Direction) -> Option<SyntaxNodeRef> {
+    node.siblings(direction)
+        .skip(1)
+        .find(|node| !node.kind().is_trivia())
+}
+
+/// `AssistCtx` allows to apply an assist or check if it could be applied.
+///
+/// Assists use a somewhat overengeneered approach, given the current needs. The
+/// assists workflow consists of two phases. In the first phase, a user asks for
+/// the list of available assists. In the second phase, the user picks a
+/// particular assist and it gets applied.
+///
+/// There are two peculiarities here:
+///
+/// * first, we ideally avoid computing more things then neccessary to answer
+///   "is assist applicable" in the first phase.
+/// * second, when we are appling assist, we don't have a gurantee that there
+///   weren't any changes between the point when user asked for assists and when
+///   they applied a particular assist. So, when applying assist, we need to do
+///   all the checks from scratch.
+///
+/// To avoid repeating the same code twice for both "check" and "apply"
+/// functions, we use an approach remeniscent of that of Django's function based
+/// views dealing with forms. Each assist receives a runtime parameter,
+/// `should_compute_edit`. It first check if an edit is applicable (potentially
+/// computing info required to compute the actual edit). If it is applicable,
+/// and `should_compute_edit` is `true`, it then computes the actual edit.
+///
+/// So, to implement the original assists workflow, we can first apply each edit
+/// with `should_compute_edit = false`, and then applying the selected edit
+/// again, with `should_compute_edit = true` this time.
+///
+/// Note, however, that we don't actually use such two-phase logic at the
+/// moment, because the LSP API is pretty awkward in this place, and it's much
+/// easier to just compute the edit eagarly :-)
+#[derive(Debug, Clone)]
+pub struct AssistCtx<'a> {
+    source_file: &'a SourceFileNode,
+    range: TextRange,
+    should_compute_edit: bool,
+}
+
+#[derive(Debug)]
+pub enum Assist {
+    Applicable,
+    Edit(LocalEdit),
+}
+
+#[derive(Default)]
+struct AssistBuilder {
+    edit: TextEditBuilder,
+    cursor_position: Option<TextUnit>,
+}
+
+impl<'a> AssistCtx<'a> {
+    pub fn new(source_file: &'a SourceFileNode, range: TextRange) -> AssistCtx {
+        AssistCtx {
+            source_file,
+            range,
+            should_compute_edit: false,
+        }
+    }
+
+    pub fn apply(mut self, assist: fn(AssistCtx) -> Option<Assist>) -> Option<LocalEdit> {
+        self.should_compute_edit = true;
+        match assist(self) {
+            None => None,
+            Some(Assist::Edit(e)) => Some(e),
+            Some(Assist::Applicable) => unreachable!(),
+        }
+    }
+
+    pub fn check(mut self, assist: fn(AssistCtx) -> Option<Assist>) -> bool {
+        self.should_compute_edit = false;
+        match assist(self) {
+            None => false,
+            Some(Assist::Edit(_)) => unreachable!(),
+            Some(Assist::Applicable) => true,
+        }
+    }
+
+    fn build(self, label: impl Into<String>, f: impl FnOnce(&mut AssistBuilder)) -> Option<Assist> {
+        if !self.should_compute_edit {
+            return Some(Assist::Applicable);
+        }
+        let mut edit = AssistBuilder::default();
+        f(&mut edit);
+        Some(Assist::Edit(LocalEdit {
+            label: label.into(),
+            edit: edit.edit.finish(),
+            cursor_position: edit.cursor_position,
+        }))
+    }
+
+    pub(crate) fn leaf_at_offset(&self) -> LeafAtOffset<SyntaxNodeRef<'a>> {
+        find_leaf_at_offset(self.source_file.syntax(), self.range.start())
+    }
+    pub(crate) fn node_at_offset<N: AstNode<'a>>(&self) -> Option<N> {
+        find_node_at_offset(self.source_file.syntax(), self.range.start())
+    }
+    pub(crate) fn covering_node(&self) -> SyntaxNodeRef<'a> {
+        find_covering_node(self.source_file.syntax(), self.range)
+    }
+}
+
+impl AssistBuilder {
+    fn replace(&mut self, range: TextRange, replace_with: impl Into<String>) {
+        self.edit.replace(range, replace_with.into())
+    }
+    #[allow(unused)]
+    fn delete(&mut self, range: TextRange) {
+        self.edit.delete(range)
+    }
+    fn insert(&mut self, offset: TextUnit, text: impl Into<String>) {
+        self.edit.insert(offset, text.into())
+    }
+    fn set_cursor(&mut self, offset: TextUnit) {
+        self.cursor_position = Some(offset)
+    }
+}
+
+#[cfg(test)]
+fn check_assist(assist: fn(AssistCtx) -> Option<Assist>, before: &str, after: &str) {
+    crate::test_utils::check_action(before, after, |file, off| {
+        let range = TextRange::offset_len(off, 0.into());
+        AssistCtx::new(file, range).apply(assist)
+    })
+}
+
+#[cfg(test)]
+fn check_assist_range(assist: fn(AssistCtx) -> Option<Assist>, before: &str, after: &str) {
+    crate::test_utils::check_action_range(before, after, |file, range| {
+        AssistCtx::new(file, range).apply(assist)
+    })
+}
diff --git a/crates/ra_editor/src/assists/add_derive.rs b/crates/ra_editor/src/assists/add_derive.rs
new file mode 100644
index 000000000..1e2cd4f30
--- /dev/null
+++ b/crates/ra_editor/src/assists/add_derive.rs
@@ -0,0 +1,84 @@
+use ra_syntax::{
+    ast::{self, AstNode, AttrsOwner},
+    SyntaxKind::{WHITESPACE, COMMENT},
+    TextUnit,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn add_derive(ctx: AssistCtx) -> Option<Assist> {
+    let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
+    let node_start = derive_insertion_offset(nominal)?;
+    ctx.build("add `#[derive]`", |edit| {
+        let derive_attr = nominal
+            .attrs()
+            .filter_map(|x| x.as_call())
+            .filter(|(name, _arg)| name == "derive")
+            .map(|(_name, arg)| arg)
+            .next();
+        let offset = match derive_attr {
+            None => {
+                edit.insert(node_start, "#[derive()]\n");
+                node_start + TextUnit::of_str("#[derive(")
+            }
+            Some(tt) => tt.syntax().range().end() - TextUnit::of_char(')'),
+        };
+        edit.set_cursor(offset)
+    })
+}
+
+// Insert `derive` after doc comments.
+fn derive_insertion_offset(nominal: ast::NominalDef) -> Option<TextUnit> {
+    let non_ws_child = nominal
+        .syntax()
+        .children()
+        .find(|it| it.kind() != COMMENT && it.kind() != WHITESPACE)?;
+    Some(non_ws_child.range().start())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn add_derive_new() {
+        check_assist(
+            add_derive,
+            "struct Foo { a: i32, <|>}",
+            "#[derive(<|>)]\nstruct Foo { a: i32, }",
+        );
+        check_assist(
+            add_derive,
+            "struct Foo { <|> a: i32, }",
+            "#[derive(<|>)]\nstruct Foo {  a: i32, }",
+        );
+    }
+
+    #[test]
+    fn add_derive_existing() {
+        check_assist(
+            add_derive,
+            "#[derive(Clone)]\nstruct Foo { a: i32<|>, }",
+            "#[derive(Clone<|>)]\nstruct Foo { a: i32, }",
+        );
+    }
+
+    #[test]
+    fn add_derive_new_with_doc_comment() {
+        check_assist(
+            add_derive,
+            "
+/// `Foo` is a pretty important struct.
+/// It does stuff.
+struct Foo { a: i32<|>, }
+            ",
+            "
+/// `Foo` is a pretty important struct.
+/// It does stuff.
+#[derive(<|>)]
+struct Foo { a: i32, }
+            ",
+        );
+    }
+}
diff --git a/crates/ra_editor/src/assists/add_impl.rs b/crates/ra_editor/src/assists/add_impl.rs
new file mode 100644
index 000000000..9353e2717
--- /dev/null
+++ b/crates/ra_editor/src/assists/add_impl.rs
@@ -0,0 +1,66 @@
+use join_to_string::join;
+use ra_syntax::{
+    ast::{self, AstNode, NameOwner, TypeParamsOwner},
+    TextUnit,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn add_impl(ctx: AssistCtx) -> Option<Assist> {
+    let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
+    let name = nominal.name()?;
+    ctx.build("add impl", |edit| {
+        let type_params = nominal.type_param_list();
+        let start_offset = nominal.syntax().range().end();
+        let mut buf = String::new();
+        buf.push_str("\n\nimpl");
+        if let Some(type_params) = type_params {
+            type_params.syntax().text().push_to(&mut buf);
+        }
+        buf.push_str(" ");
+        buf.push_str(name.text().as_str());
+        if let Some(type_params) = type_params {
+            let lifetime_params = type_params
+                .lifetime_params()
+                .filter_map(|it| it.lifetime())
+                .map(|it| it.text());
+            let type_params = type_params
+                .type_params()
+                .filter_map(|it| it.name())
+                .map(|it| it.text());
+            join(lifetime_params.chain(type_params))
+                .surround_with("<", ">")
+                .to_buf(&mut buf);
+        }
+        buf.push_str(" {\n");
+        edit.set_cursor(start_offset + TextUnit::of_str(&buf));
+        buf.push_str("\n}");
+        edit.insert(start_offset, buf);
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn test_add_impl() {
+        check_assist(
+            add_impl,
+            "struct Foo {<|>}\n",
+            "struct Foo {}\n\nimpl Foo {\n<|>\n}\n",
+        );
+        check_assist(
+            add_impl,
+            "struct Foo<T: Clone> {<|>}",
+            "struct Foo<T: Clone> {}\n\nimpl<T: Clone> Foo<T> {\n<|>\n}",
+        );
+        check_assist(
+            add_impl,
+            "struct Foo<'a, T: Foo<'a>> {<|>}",
+            "struct Foo<'a, T: Foo<'a>> {}\n\nimpl<'a, T: Foo<'a>> Foo<'a, T> {\n<|>\n}",
+        );
+    }
+
+}
diff --git a/crates/ra_editor/src/assists/change_visibility.rs b/crates/ra_editor/src/assists/change_visibility.rs
new file mode 100644
index 000000000..6c8466394
--- /dev/null
+++ b/crates/ra_editor/src/assists/change_visibility.rs
@@ -0,0 +1,116 @@
+use ra_syntax::{
+    AstNode,
+    ast::{self, VisibilityOwner, NameOwner},
+    SyntaxKind::{VISIBILITY, FN_KW, MOD_KW, STRUCT_KW, ENUM_KW, TRAIT_KW, FN_DEF, MODULE, STRUCT_DEF, ENUM_DEF, TRAIT_DEF, IDENT},
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn change_visibility(ctx: AssistCtx) -> Option<Assist> {
+    if let Some(vis) = ctx.node_at_offset::<ast::Visibility>() {
+        return change_vis(ctx, vis);
+    }
+    add_vis(ctx)
+}
+
+fn add_vis(ctx: AssistCtx) -> Option<Assist> {
+    let item_keyword = ctx.leaf_at_offset().find(|leaf| match leaf.kind() {
+        FN_KW | MOD_KW | STRUCT_KW | ENUM_KW | TRAIT_KW => true,
+        _ => false,
+    });
+
+    let offset = if let Some(keyword) = item_keyword {
+        let parent = keyword.parent()?;
+        let def_kws = vec![FN_DEF, MODULE, STRUCT_DEF, ENUM_DEF, TRAIT_DEF];
+        // Parent is not a definition, can't add visibility
+        if !def_kws.iter().any(|&def_kw| def_kw == parent.kind()) {
+            return None;
+        }
+        // Already have visibility, do nothing
+        if parent.children().any(|child| child.kind() == VISIBILITY) {
+            return None;
+        }
+        parent.range().start()
+    } else {
+        let ident = ctx.leaf_at_offset().find(|leaf| leaf.kind() == IDENT)?;
+        let field = ident.ancestors().find_map(ast::NamedFieldDef::cast)?;
+        if field.name()?.syntax().range() != ident.range() && field.visibility().is_some() {
+            return None;
+        }
+        field.syntax().range().start()
+    };
+
+    ctx.build("make pub(crate)", |edit| {
+        edit.insert(offset, "pub(crate) ");
+        edit.set_cursor(offset);
+    })
+}
+
+fn change_vis(ctx: AssistCtx, vis: ast::Visibility) -> Option<Assist> {
+    if vis.syntax().text() != "pub" {
+        return None;
+    }
+    ctx.build("chage to pub(crate)", |edit| {
+        edit.replace(vis.syntax().range(), "pub(crate)");
+        edit.set_cursor(vis.syntax().range().start());
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn change_visibility_adds_pub_crate_to_items() {
+        check_assist(
+            change_visibility,
+            "<|>fn foo() {}",
+            "<|>pub(crate) fn foo() {}",
+        );
+        check_assist(
+            change_visibility,
+            "f<|>n foo() {}",
+            "<|>pub(crate) fn foo() {}",
+        );
+        check_assist(
+            change_visibility,
+            "<|>struct Foo {}",
+            "<|>pub(crate) struct Foo {}",
+        );
+        check_assist(
+            change_visibility,
+            "<|>mod foo {}",
+            "<|>pub(crate) mod foo {}",
+        );
+        check_assist(
+            change_visibility,
+            "<|>trait Foo {}",
+            "<|>pub(crate) trait Foo {}",
+        );
+        check_assist(change_visibility, "m<|>od {}", "<|>pub(crate) mod {}");
+        check_assist(
+            change_visibility,
+            "unsafe f<|>n foo() {}",
+            "<|>pub(crate) unsafe fn foo() {}",
+        );
+    }
+
+    #[test]
+    fn change_visibility_works_with_struct_fields() {
+        check_assist(
+            change_visibility,
+            "struct S { <|>field: u32 }",
+            "struct S { <|>pub(crate) field: u32 }",
+        )
+    }
+
+    #[test]
+    fn change_visibility_pub_to_pub_crate() {
+        check_assist(
+            change_visibility,
+            "<|>pub fn foo() {}",
+            "<|>pub(crate) fn foo() {}",
+        )
+    }
+}
diff --git a/crates/ra_editor/src/assists/flip_comma.rs b/crates/ra_editor/src/assists/flip_comma.rs
new file mode 100644
index 000000000..a343413cc
--- /dev/null
+++ b/crates/ra_editor/src/assists/flip_comma.rs
@@ -0,0 +1,31 @@
+use ra_syntax::{
+    Direction,
+    SyntaxKind::COMMA,
+};
+
+use crate::assists::{non_trivia_sibling, AssistCtx, Assist};
+
+pub fn flip_comma(ctx: AssistCtx) -> Option<Assist> {
+    let comma = ctx.leaf_at_offset().find(|leaf| leaf.kind() == COMMA)?;
+    let prev = non_trivia_sibling(comma, Direction::Prev)?;
+    let next = non_trivia_sibling(comma, Direction::Next)?;
+    ctx.build("flip comma", |edit| {
+        edit.replace(prev.range(), next.text());
+        edit.replace(next.range(), prev.text());
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn flip_comma_works_for_function_parameters() {
+        check_assist(
+            flip_comma,
+            "fn foo(x: i32,<|> y: Result<(), ()>) {}",
+            "fn foo(y: Result<(), ()>,<|> x: i32) {}",
+        )
+    }
+}
diff --git a/crates/ra_editor/src/assists/introduce_variable.rs b/crates/ra_editor/src/assists/introduce_variable.rs
new file mode 100644
index 000000000..782861023
--- /dev/null
+++ b/crates/ra_editor/src/assists/introduce_variable.rs
@@ -0,0 +1,144 @@
+use ra_syntax::{
+    ast::{self, AstNode},
+    SyntaxKind::WHITESPACE,
+    SyntaxNodeRef, TextUnit,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn introduce_variable<'a>(ctx: AssistCtx) -> Option<Assist> {
+    let node = ctx.covering_node();
+    let expr = node.ancestors().filter_map(ast::Expr::cast).next()?;
+
+    let anchor_stmt = anchor_stmt(expr)?;
+    let indent = anchor_stmt.prev_sibling()?;
+    if indent.kind() != WHITESPACE {
+        return None;
+    }
+    ctx.build("introduce variable", move |edit| {
+        let mut buf = String::new();
+
+        buf.push_str("let var_name = ");
+        expr.syntax().text().push_to(&mut buf);
+        let is_full_stmt = if let Some(expr_stmt) = ast::ExprStmt::cast(anchor_stmt) {
+            Some(expr.syntax()) == expr_stmt.expr().map(|e| e.syntax())
+        } else {
+            false
+        };
+        if is_full_stmt {
+            edit.replace(expr.syntax().range(), buf);
+        } else {
+            buf.push_str(";");
+            indent.text().push_to(&mut buf);
+            edit.replace(expr.syntax().range(), "var_name".to_string());
+            edit.insert(anchor_stmt.range().start(), buf);
+        }
+        edit.set_cursor(anchor_stmt.range().start() + TextUnit::of_str("let "));
+    })
+}
+
+/// Statement or last in the block expression, which will follow
+/// the freshly introduced var.
+fn anchor_stmt(expr: ast::Expr) -> Option<SyntaxNodeRef> {
+    expr.syntax().ancestors().find(|&node| {
+        if ast::Stmt::cast(node).is_some() {
+            return true;
+        }
+        if let Some(expr) = node
+            .parent()
+            .and_then(ast::Block::cast)
+            .and_then(|it| it.expr())
+        {
+            if expr.syntax() == node {
+                return true;
+            }
+        }
+        false
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist_range;
+
+    #[test]
+    fn test_introduce_var_simple() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    foo(<|>1 + 1<|>);
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+    foo(var_name);
+}",
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_expr_stmt() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    <|>1 + 1<|>;
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+}",
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_part_of_expr_stmt() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    <|>1<|> + 1;
+}",
+            "
+fn foo() {
+    let <|>var_name = 1;
+    var_name + 1;
+}",
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_last_expr() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    bar(<|>1 + 1<|>)
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+    bar(var_name)
+}",
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_last_full_expr() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    <|>bar(1 + 1)<|>
+}",
+            "
+fn foo() {
+    let <|>var_name = bar(1 + 1);
+    var_name
+}",
+        );
+    }
+
+}
diff --git a/crates/ra_editor/src/assists/split_import.rs b/crates/ra_editor/src/assists/split_import.rs
new file mode 100644
index 000000000..75f9e8dfb
--- /dev/null
+++ b/crates/ra_editor/src/assists/split_import.rs
@@ -0,0 +1,44 @@
+use ra_syntax::{
+    TextUnit, AstNode, SyntaxKind::COLONCOLON,
+    ast,
+    algo::generate,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn split_import(ctx: AssistCtx) -> Option<Assist> {
+    let colon_colon = ctx
+        .leaf_at_offset()
+        .find(|leaf| leaf.kind() == COLONCOLON)?;
+    let path = colon_colon.parent().and_then(ast::Path::cast)?;
+    let top_path = generate(Some(path), |it| it.parent_path()).last()?;
+
+    let use_tree = top_path.syntax().ancestors().find_map(ast::UseTree::cast);
+    if use_tree.is_none() {
+        return None;
+    }
+
+    let l_curly = colon_colon.range().end();
+    let r_curly = top_path.syntax().range().end();
+
+    ctx.build("split import", |edit| {
+        edit.insert(l_curly, "{");
+        edit.insert(r_curly, "}");
+        edit.set_cursor(l_curly + TextUnit::of_str("{"));
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn test_split_import() {
+        check_assist(
+            split_import,
+            "use crate::<|>db::RootDatabase;",
+            "use crate::{<|>db::RootDatabase};",
+        )
+    }
+}
diff --git a/crates/ra_editor/src/code_actions.rs b/crates/ra_editor/src/code_actions.rs
deleted file mode 100644
index 7615f37a6..000000000
--- a/crates/ra_editor/src/code_actions.rs
+++ /dev/null
@@ -1,415 +0,0 @@
-use join_to_string::join;
-
-use ra_syntax::{
-    algo::{find_covering_node, find_leaf_at_offset},
-    ast::{self, AstNode, AttrsOwner, NameOwner, TypeParamsOwner},
-    Direction, SourceFileNode,
-    SyntaxKind::{COMMA, WHITESPACE, COMMENT, VISIBILITY, FN_KW, MOD_KW, STRUCT_KW, ENUM_KW, TRAIT_KW, FN_DEF, MODULE, STRUCT_DEF, ENUM_DEF, TRAIT_DEF},
-    SyntaxNodeRef, TextRange, TextUnit,
-};
-
-use crate::{find_node_at_offset, TextEdit, TextEditBuilder};
-
-#[derive(Debug)]
-pub struct LocalEdit {
-    pub label: String,
-    pub edit: TextEdit,
-    pub cursor_position: Option<TextUnit>,
-}
-
-pub fn flip_comma<'a>(
-    file: &'a SourceFileNode,
-    offset: TextUnit,
-) -> Option<impl FnOnce() -> LocalEdit + 'a> {
-    let syntax = file.syntax();
-
-    let comma = find_leaf_at_offset(syntax, offset).find(|leaf| leaf.kind() == COMMA)?;
-    let prev = non_trivia_sibling(comma, Direction::Prev)?;
-    let next = non_trivia_sibling(comma, Direction::Next)?;
-    Some(move || {
-        let mut edit = TextEditBuilder::new();
-        edit.replace(prev.range(), next.text().to_string());
-        edit.replace(next.range(), prev.text().to_string());
-        LocalEdit {
-            label: "flip comma".to_string(),
-            edit: edit.finish(),
-            cursor_position: None,
-        }
-    })
-}
-
-pub fn add_derive<'a>(
-    file: &'a SourceFileNode,
-    offset: TextUnit,
-) -> Option<impl FnOnce() -> LocalEdit + 'a> {
-    let nominal = find_node_at_offset::<ast::NominalDef>(file.syntax(), offset)?;
-    let node_start = derive_insertion_offset(nominal)?;
-    return Some(move || {
-        let derive_attr = nominal
-            .attrs()
-            .filter_map(|x| x.as_call())
-            .filter(|(name, _arg)| name == "derive")
-            .map(|(_name, arg)| arg)
-            .next();
-        let mut edit = TextEditBuilder::new();
-        let offset = match derive_attr {
-            None => {
-                edit.insert(node_start, "#[derive()]\n".to_string());
-                node_start + TextUnit::of_str("#[derive(")
-            }
-            Some(tt) => tt.syntax().range().end() - TextUnit::of_char(')'),
-        };
-        LocalEdit {
-            label: "add `#[derive]`".to_string(),
-            edit: edit.finish(),
-            cursor_position: Some(offset),
-        }
-    });
-
-    // Insert `derive` after doc comments.
-    fn derive_insertion_offset(nominal: ast::NominalDef) -> Option<TextUnit> {
-        let non_ws_child = nominal
-            .syntax()
-            .children()
-            .find(|it| it.kind() != COMMENT && it.kind() != WHITESPACE)?;
-        Some(non_ws_child.range().start())
-    }
-}
-
-pub fn add_impl<'a>(
-    file: &'a SourceFileNode,
-    offset: TextUnit,
-) -> Option<impl FnOnce() -> LocalEdit + 'a> {
-    let nominal = find_node_at_offset::<ast::NominalDef>(file.syntax(), offset)?;
-    let name = nominal.name()?;
-
-    Some(move || {
-        let type_params = nominal.type_param_list();
-        let mut edit = TextEditBuilder::new();
-        let start_offset = nominal.syntax().range().end();
-        let mut buf = String::new();
-        buf.push_str("\n\nimpl");
-        if let Some(type_params) = type_params {
-            type_params.syntax().text().push_to(&mut buf);
-        }
-        buf.push_str(" ");
-        buf.push_str(name.text().as_str());
-        if let Some(type_params) = type_params {
-            let lifetime_params = type_params
-                .lifetime_params()
-                .filter_map(|it| it.lifetime())
-                .map(|it| it.text());
-            let type_params = type_params
-                .type_params()
-                .filter_map(|it| it.name())
-                .map(|it| it.text());
-            join(lifetime_params.chain(type_params))
-                .surround_with("<", ">")
-                .to_buf(&mut buf);
-        }
-        buf.push_str(" {\n");
-        let offset = start_offset + TextUnit::of_str(&buf);
-        buf.push_str("\n}");
-        edit.insert(start_offset, buf);
-        LocalEdit {
-            label: "add impl".to_string(),
-            edit: edit.finish(),
-            cursor_position: Some(offset),
-        }
-    })
-}
-
-pub fn introduce_variable<'a>(
-    file: &'a SourceFileNode,
-    range: TextRange,
-) -> Option<impl FnOnce() -> LocalEdit + 'a> {
-    let node = find_covering_node(file.syntax(), range);
-    let expr = node.ancestors().filter_map(ast::Expr::cast).next()?;
-
-    let anchor_stmt = anchor_stmt(expr)?;
-    let indent = anchor_stmt.prev_sibling()?;
-    if indent.kind() != WHITESPACE {
-        return None;
-    }
-    return Some(move || {
-        let mut buf = String::new();
-        let mut edit = TextEditBuilder::new();
-
-        buf.push_str("let var_name = ");
-        expr.syntax().text().push_to(&mut buf);
-        let is_full_stmt = if let Some(expr_stmt) = ast::ExprStmt::cast(anchor_stmt) {
-            Some(expr.syntax()) == expr_stmt.expr().map(|e| e.syntax())
-        } else {
-            false
-        };
-        if is_full_stmt {
-            edit.replace(expr.syntax().range(), buf);
-        } else {
-            buf.push_str(";");
-            indent.text().push_to(&mut buf);
-            edit.replace(expr.syntax().range(), "var_name".to_string());
-            edit.insert(anchor_stmt.range().start(), buf);
-        }
-        let cursor_position = anchor_stmt.range().start() + TextUnit::of_str("let ");
-        LocalEdit {
-            label: "introduce variable".to_string(),
-            edit: edit.finish(),
-            cursor_position: Some(cursor_position),
-        }
-    });
-
-    /// Statement or last in the block expression, which will follow
-    /// the freshly introduced var.
-    fn anchor_stmt(expr: ast::Expr) -> Option<SyntaxNodeRef> {
-        expr.syntax().ancestors().find(|&node| {
-            if ast::Stmt::cast(node).is_some() {
-                return true;
-            }
-            if let Some(expr) = node
-                .parent()
-                .and_then(ast::Block::cast)
-                .and_then(|it| it.expr())
-            {
-                if expr.syntax() == node {
-                    return true;
-                }
-            }
-            false
-        })
-    }
-}
-
-pub fn make_pub_crate<'a>(
-    file: &'a SourceFileNode,
-    offset: TextUnit,
-) -> Option<impl FnOnce() -> LocalEdit + 'a> {
-    let syntax = file.syntax();
-
-    let keyword = find_leaf_at_offset(syntax, offset).find(|leaf| match leaf.kind() {
-        FN_KW | MOD_KW | STRUCT_KW | ENUM_KW | TRAIT_KW => true,
-        _ => false,
-    })?;
-    let parent = keyword.parent()?;
-    let def_kws = vec![FN_DEF, MODULE, STRUCT_DEF, ENUM_DEF, TRAIT_DEF];
-    let node_start = parent.range().start();
-    Some(move || {
-        let mut edit = TextEditBuilder::new();
-
-        if !def_kws.iter().any(|&def_kw| def_kw == parent.kind())
-            || parent.children().any(|child| child.kind() == VISIBILITY)
-        {
-            return LocalEdit {
-                label: "make pub crate".to_string(),
-                edit: edit.finish(),
-                cursor_position: Some(offset),
-            };
-        }
-
-        edit.insert(node_start, "pub(crate) ".to_string());
-        LocalEdit {
-            label: "make pub crate".to_string(),
-            edit: edit.finish(),
-            cursor_position: Some(node_start),
-        }
-    })
-}
-
-fn non_trivia_sibling(node: SyntaxNodeRef, direction: Direction) -> Option<SyntaxNodeRef> {
-    node.siblings(direction)
-        .skip(1)
-        .find(|node| !node.kind().is_trivia())
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::test_utils::{check_action, check_action_range};
-
-    #[test]
-    fn test_swap_comma() {
-        check_action(
-            "fn foo(x: i32,<|> y: Result<(), ()>) {}",
-            "fn foo(y: Result<(), ()>,<|> x: i32) {}",
-            |file, off| flip_comma(file, off).map(|f| f()),
-        )
-    }
-
-    #[test]
-    fn add_derive_new() {
-        check_action(
-            "struct Foo { a: i32, <|>}",
-            "#[derive(<|>)]\nstruct Foo { a: i32, }",
-            |file, off| add_derive(file, off).map(|f| f()),
-        );
-        check_action(
-            "struct Foo { <|> a: i32, }",
-            "#[derive(<|>)]\nstruct Foo {  a: i32, }",
-            |file, off| add_derive(file, off).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn add_derive_existing() {
-        check_action(
-            "#[derive(Clone)]\nstruct Foo { a: i32<|>, }",
-            "#[derive(Clone<|>)]\nstruct Foo { a: i32, }",
-            |file, off| add_derive(file, off).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn add_derive_new_with_doc_comment() {
-        check_action(
-            "
-/// `Foo` is a pretty important struct.
-/// It does stuff.
-struct Foo { a: i32<|>, }
-            ",
-            "
-/// `Foo` is a pretty important struct.
-/// It does stuff.
-#[derive(<|>)]
-struct Foo { a: i32, }
-            ",
-            |file, off| add_derive(file, off).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn test_add_impl() {
-        check_action(
-            "struct Foo {<|>}\n",
-            "struct Foo {}\n\nimpl Foo {\n<|>\n}\n",
-            |file, off| add_impl(file, off).map(|f| f()),
-        );
-        check_action(
-            "struct Foo<T: Clone> {<|>}",
-            "struct Foo<T: Clone> {}\n\nimpl<T: Clone> Foo<T> {\n<|>\n}",
-            |file, off| add_impl(file, off).map(|f| f()),
-        );
-        check_action(
-            "struct Foo<'a, T: Foo<'a>> {<|>}",
-            "struct Foo<'a, T: Foo<'a>> {}\n\nimpl<'a, T: Foo<'a>> Foo<'a, T> {\n<|>\n}",
-            |file, off| add_impl(file, off).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn test_introduce_var_simple() {
-        check_action_range(
-            "
-fn foo() {
-    foo(<|>1 + 1<|>);
-}",
-            "
-fn foo() {
-    let <|>var_name = 1 + 1;
-    foo(var_name);
-}",
-            |file, range| introduce_variable(file, range).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn test_introduce_var_expr_stmt() {
-        check_action_range(
-            "
-fn foo() {
-    <|>1 + 1<|>;
-}",
-            "
-fn foo() {
-    let <|>var_name = 1 + 1;
-}",
-            |file, range| introduce_variable(file, range).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn test_introduce_var_part_of_expr_stmt() {
-        check_action_range(
-            "
-fn foo() {
-    <|>1<|> + 1;
-}",
-            "
-fn foo() {
-    let <|>var_name = 1;
-    var_name + 1;
-}",
-            |file, range| introduce_variable(file, range).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn test_introduce_var_last_expr() {
-        check_action_range(
-            "
-fn foo() {
-    bar(<|>1 + 1<|>)
-}",
-            "
-fn foo() {
-    let <|>var_name = 1 + 1;
-    bar(var_name)
-}",
-            |file, range| introduce_variable(file, range).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn test_introduce_var_last_full_expr() {
-        check_action_range(
-            "
-fn foo() {
-    <|>bar(1 + 1)<|>
-}",
-            "
-fn foo() {
-    let <|>var_name = bar(1 + 1);
-    var_name
-}",
-            |file, range| introduce_variable(file, range).map(|f| f()),
-        );
-    }
-
-    #[test]
-    fn test_make_pub_crate() {
-        check_action(
-            "<|>fn foo() {}",
-            "<|>pub(crate) fn foo() {}",
-            |file, off| make_pub_crate(file, off).map(|f| f()),
-        );
-        check_action(
-            "f<|>n foo() {}",
-            "<|>pub(crate) fn foo() {}",
-            |file, off| make_pub_crate(file, off).map(|f| f()),
-        );
-        check_action(
-            "<|>struct Foo {}",
-            "<|>pub(crate) struct Foo {}",
-            |file, off| make_pub_crate(file, off).map(|f| f()),
-        );
-        check_action("<|>mod foo {}", "<|>pub(crate) mod foo {}", |file, off| {
-            make_pub_crate(file, off).map(|f| f())
-        });
-        check_action(
-            "<|>trait Foo {}",
-            "<|>pub(crate) trait Foo {}",
-            |file, off| make_pub_crate(file, off).map(|f| f()),
-        );
-        check_action("m<|>od {}", "<|>pub(crate) mod {}", |file, off| {
-            make_pub_crate(file, off).map(|f| f())
-        });
-        check_action(
-            "pub(crate) f<|>n foo() {}",
-            "pub(crate) f<|>n foo() {}",
-            |file, off| make_pub_crate(file, off).map(|f| f()),
-        );
-        check_action(
-            "unsafe f<|>n foo() {}",
-            "<|>pub(crate) unsafe fn foo() {}",
-            |file, off| make_pub_crate(file, off).map(|f| f()),
-        );
-    }
-}
diff --git a/crates/ra_editor/src/diagnostics.rs b/crates/ra_editor/src/diagnostics.rs
index 1b336cfe2..199b0e502 100644
--- a/crates/ra_editor/src/diagnostics.rs
+++ b/crates/ra_editor/src/diagnostics.rs
@@ -57,7 +57,7 @@ fn check_unnecessary_braces_in_use_statement(
             text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(single_use_tree)
                 .unwrap_or_else(|| {
                     let to_replace = single_use_tree.syntax().text().to_string();
-                    let mut edit_builder = TextEditBuilder::new();
+                    let mut edit_builder = TextEditBuilder::default();
                     edit_builder.delete(range);
                     edit_builder.insert(range.start(), to_replace);
                     edit_builder.finish()
@@ -93,7 +93,7 @@ fn text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(
         let start = use_tree_list_node.prev_sibling()?.range().start();
         let end = use_tree_list_node.range().end();
         let range = TextRange::from_to(start, end);
-        let mut edit_builder = TextEditBuilder::new();
+        let mut edit_builder = TextEditBuilder::default();
         edit_builder.delete(range);
         return Some(edit_builder.finish());
     }
@@ -111,7 +111,7 @@ fn check_struct_shorthand_initialization(
             let field_name = name_ref.syntax().text().to_string();
             let field_expr = expr.syntax().text().to_string();
             if field_name == field_expr {
-                let mut edit_builder = TextEditBuilder::new();
+                let mut edit_builder = TextEditBuilder::default();
                 edit_builder.delete(named_field.syntax().range());
                 edit_builder.insert(named_field.syntax().range().start(), field_name);
                 let edit = edit_builder.finish();
diff --git a/crates/ra_editor/src/lib.rs b/crates/ra_editor/src/lib.rs
index bfc745e58..ac283e2e0 100644
--- a/crates/ra_editor/src/lib.rs
+++ b/crates/ra_editor/src/lib.rs
@@ -1,4 +1,4 @@
-mod code_actions;
+pub mod assists;
 mod extend_selection;
 mod folding_ranges;
 mod line_index;
@@ -10,7 +10,7 @@ mod typing;
 mod diagnostics;
 
 pub use self::{
-    code_actions::{add_derive, add_impl, flip_comma, introduce_variable, make_pub_crate, LocalEdit},
+    assists::LocalEdit,
     extend_selection::extend_selection,
     folding_ranges::{folding_ranges, Fold, FoldKind},
     line_index::{LineCol, LineIndex},
@@ -19,7 +19,7 @@ pub use self::{
     typing::{join_lines, on_enter, on_eq_typed},
     diagnostics::diagnostics
 };
-use ra_text_edit::{TextEdit, TextEditBuilder};
+use ra_text_edit::TextEditBuilder;
 use ra_syntax::{
     algo::find_leaf_at_offset,
     ast::{self, AstNode},
diff --git a/crates/ra_editor/src/structure.rs b/crates/ra_editor/src/structure.rs
index 2292b1ddf..32d59e335 100644
--- a/crates/ra_editor/src/structure.rs
+++ b/crates/ra_editor/src/structure.rs
@@ -60,7 +60,7 @@ fn structure_node(node: SyntaxNodeRef) -> Option<StructureNode> {
         .visit(decl::<ast::TypeDef>)
         .visit(decl::<ast::ConstDef>)
         .visit(decl::<ast::StaticDef>)
-        .visit(|im: ast::ImplItem| {
+        .visit(|im: ast::ImplBlock| {
             let target_type = im.target_type()?;
             let target_trait = im.target_trait();
             let label = match target_trait {
@@ -121,8 +121,8 @@ impl fmt::Debug for E {}
                 StructureNode { parent: None, label: "T", navigation_range: [81; 82), node_range: [76; 88), kind: TYPE_DEF },
                 StructureNode { parent: None, label: "S", navigation_range: [96; 97), node_range: [89; 108), kind: STATIC_DEF },
                 StructureNode { parent: None, label: "C", navigation_range: [115; 116), node_range: [109; 127), kind: CONST_DEF },
-                StructureNode { parent: None, label: "impl E", navigation_range: [134; 135), node_range: [129; 138), kind: IMPL_ITEM },
-                StructureNode { parent: None, label: "impl fmt::Debug for E", navigation_range: [160; 161), node_range: [140; 164), kind: IMPL_ITEM }]"#,
+                StructureNode { parent: None, label: "impl E", navigation_range: [134; 135), node_range: [129; 138), kind: IMPL_BLOCK },
+                StructureNode { parent: None, label: "impl fmt::Debug for E", navigation_range: [160; 161), node_range: [140; 164), kind: IMPL_BLOCK }]"#,
             &structure,
         )
     }
diff --git a/crates/ra_editor/src/typing.rs b/crates/ra_editor/src/typing.rs
index 21d068a7b..1b568e96c 100644
--- a/crates/ra_editor/src/typing.rs
+++ b/crates/ra_editor/src/typing.rs
@@ -21,7 +21,7 @@ pub fn join_lines(file: &SourceFileNode, range: TextRange) -> LocalEdit {
             None => {
                 return LocalEdit {
                     label: "join lines".to_string(),
-                    edit: TextEditBuilder::new().finish(),
+                    edit: TextEditBuilder::default().finish(),
                     cursor_position: None,
                 };
             }
@@ -33,7 +33,7 @@ pub fn join_lines(file: &SourceFileNode, range: TextRange) -> LocalEdit {
     };
 
     let node = find_covering_node(file.syntax(), range);
-    let mut edit = TextEditBuilder::new();
+    let mut edit = TextEditBuilder::default();
     for node in node.descendants() {
         let text = match node.leaf_text() {
             Some(text) => text,
@@ -76,7 +76,7 @@ pub fn on_enter(file: &SourceFileNode, offset: TextUnit) -> Option<LocalEdit> {
     let indent = node_indent(file, comment.syntax())?;
     let inserted = format!("\n{}{} ", indent, prefix);
     let cursor_position = offset + TextUnit::of_str(&inserted);
-    let mut edit = TextEditBuilder::new();
+    let mut edit = TextEditBuilder::default();
     edit.insert(offset, inserted);
     Some(LocalEdit {
         label: "on enter".to_string(),
@@ -127,7 +127,7 @@ pub fn on_eq_typed(file: &SourceFileNode, offset: TextUnit) -> Option<LocalEdit>
         return None;
     }
     let offset = let_stmt.syntax().range().end();
-    let mut edit = TextEditBuilder::new();
+    let mut edit = TextEditBuilder::default();
     edit.insert(offset, ";".to_string());
     Some(LocalEdit {
         label: "add semicolon".to_string(),
@@ -188,10 +188,14 @@ fn remove_newline(
         edit.delete(TextRange::from_to(prev.range().start(), node.range().end()));
     } else if prev.kind() == COMMA && next.kind() == R_CURLY {
         // Removes: comma, newline (incl. surrounding whitespace)
-        // Adds: a single whitespace
+        let space = if let Some(left) = prev.prev_sibling() {
+            compute_ws(left, next)
+        } else {
+            " "
+        };
         edit.replace(
             TextRange::from_to(prev.range().start(), node.range().end()),
-            " ".to_string(),
+            space.to_string(),
         );
     } else if let (Some(_), Some(next)) = (ast::Comment::cast(prev), ast::Comment::cast(next)) {
         // Removes: newline (incl. surrounding whitespace), start of the next comment
@@ -256,10 +260,20 @@ fn join_single_use_tree(edit: &mut TextEditBuilder, node: SyntaxNodeRef) -> Opti
 fn compute_ws(left: SyntaxNodeRef, right: SyntaxNodeRef) -> &'static str {
     match left.kind() {
         L_PAREN | L_BRACK => return "",
+        L_CURLY => {
+            if let USE_TREE = right.kind() {
+                return "";
+            }
+        }
         _ => (),
     }
     match right.kind() {
         R_PAREN | R_BRACK => return "",
+        R_CURLY => {
+            if let USE_TREE = left.kind() {
+                return "";
+            }
+        }
         DOT => return "",
         _ => (),
     }
@@ -331,6 +345,48 @@ fn foo() {
     }
 
     #[test]
+    fn test_join_lines_use_items_left() {
+        // No space after the '{'
+        check_join_lines(
+            r"
+<|>use ra_syntax::{
+    TextUnit, TextRange,
+};",
+            r"
+<|>use ra_syntax::{TextUnit, TextRange,
+};",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_use_items_right() {
+        // No space after the '}'
+        check_join_lines(
+            r"
+use ra_syntax::{
+<|>    TextUnit, TextRange
+};",
+            r"
+use ra_syntax::{
+<|>    TextUnit, TextRange};",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_use_items_right_comma() {
+        // No space after the '}'
+        check_join_lines(
+            r"
+use ra_syntax::{
+<|>    TextUnit, TextRange,
+};",
+            r"
+use ra_syntax::{
+<|>    TextUnit, TextRange};",
+        );
+    }
+
+    #[test]
     fn test_join_lines_use_tree() {
         check_join_lines(
             r"
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index c3fbd327d..245a21ce3 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -8,12 +8,12 @@ authors = ["Aleksey Kladov <[email protected]>"]
 arrayvec = "0.4.10"
 log = "0.4.5"
 relative-path = "0.4.0"
-salsa = "0.9.0"
+salsa = "0.9.1"
 rustc-hash = "1.0"
 parking_lot = "0.7.0"
-id-arena = "2.0"
 ena = "0.11"
 ra_syntax = { path = "../ra_syntax" }
+ra_arena = { path = "../ra_arena" }
 ra_editor = { path = "../ra_editor" }
 ra_db = { path = "../ra_db" }
 test_utils = { path = "../test_utils" }
diff --git a/crates/ra_hir/src/arena.rs b/crates/ra_hir/src/arena.rs
deleted file mode 100644
index d4f9d9cb9..000000000
--- a/crates/ra_hir/src/arena.rs
+++ /dev/null
@@ -1,66 +0,0 @@
-//! A simple id-based arena, similar to https://github.com/fitzgen/id-arena.
-//! We use our own version for more compact id's and to allow inherent impls
-//! on Ids.
-
-use std::{
-    fmt,
-    hash::{Hash, Hasher},
-    marker::PhantomData,
-};
-
-pub struct Id<T> {
-    idx: u32,
-    _ty: PhantomData<fn() -> T>,
-}
-
-impl<T> fmt::Debug for Id<T> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_tuple("Id").field(&self.idx).finish()
-    }
-}
-impl<T> Copy for Id<T> {}
-impl<T> Clone for Id<T> {
-    fn clone(&self) -> Id<T> {
-        *self
-    }
-}
-
-impl<T> PartialEq for Id<T> {
-    fn eq(&self, other: &Id<T>) -> bool {
-        self.idx == other.idx
-    }
-}
-
-impl<T> Eq for Id<T> {}
-
-impl<T> Hash for Id<T> {
-    fn hash<H: Hasher>(&self, h: &mut H) {
-        self.idx.hash(h);
-    }
-}
-
-#[derive(Debug, PartialEq, Eq)]
-pub(crate) struct ArenaBehavior<T> {
-    _ty: PhantomData<T>,
-}
-
-impl<T> id_arena::ArenaBehavior for ArenaBehavior<T> {
-    type Id = Id<T>;
-    fn new_arena_id() -> u32 {
-        0
-    }
-    fn new_id(_arena_id: u32, index: usize) -> Id<T> {
-        Id {
-            idx: index as u32,
-            _ty: PhantomData,
-        }
-    }
-    fn index(id: Id<T>) -> usize {
-        id.idx as usize
-    }
-    fn arena_id(_id: Id<T>) -> u32 {
-        0
-    }
-}
-
-pub(crate) type Arena<T> = id_arena::Arena<T, ArenaBehavior<T>>;
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 73a4cdc5c..58296fc6f 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -13,6 +13,7 @@ use crate::{
     nameres::{ItemMap, InputModuleItems}},
     ty::{InferenceResult, Ty},
     adt::{StructData, EnumData},
+    impl_block::ModuleImplBlocks,
 };
 
 salsa::query_group! {
@@ -87,6 +88,11 @@ pub trait HirDatabase: SyntaxDatabase
         type ModuleTreeQuery;
         use fn crate::module::imp::module_tree;
     }
+
+    fn impls_in_module(source_root_id: SourceRootId, module_id: ModuleId) -> Cancelable<Arc<ModuleImplBlocks>> {
+        type ImplsInModuleQuery;
+        use fn crate::impl_block::impls_in_module;
+    }
 }
 
 }
diff --git a/crates/ra_hir/src/function.rs b/crates/ra_hir/src/function.rs
index 5a44132fc..75ef308ae 100644
--- a/crates/ra_hir/src/function.rs
+++ b/crates/ra_hir/src/function.rs
@@ -11,11 +11,11 @@ use ra_syntax::{
     ast::{self, AstNode, DocCommentsOwner, NameOwner},
 };
 
-use crate::{DefId, DefKind, HirDatabase, ty::InferenceResult, Module};
+use crate::{DefId, DefKind, HirDatabase, ty::InferenceResult, Module, Crate, impl_block::ImplBlock};
 
 pub use self::scope::FnScopes;
 
-#[derive(Debug)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Function {
     def_id: DefId,
 }
@@ -25,6 +25,10 @@ impl Function {
         Function { def_id }
     }
 
+    pub fn def_id(&self) -> DefId {
+        self.def_id
+    }
+
     pub fn syntax(&self, db: &impl HirDatabase) -> ast::FnDefNode {
         let def_loc = self.def_id.loc(db);
         assert!(def_loc.kind == DefKind::Function);
@@ -48,6 +52,15 @@ impl Function {
     pub fn module(&self, db: &impl HirDatabase) -> Cancelable<Module> {
         self.def_id.module(db)
     }
+
+    pub fn krate(&self, db: &impl HirDatabase) -> Cancelable<Option<Crate>> {
+        self.def_id.krate(db)
+    }
+
+    /// The containing impl block, if this is a method.
+    pub fn impl_block(&self, db: &impl HirDatabase) -> Cancelable<Option<ImplBlock>> {
+        self.def_id.impl_block(db)
+    }
 }
 
 #[derive(Debug, Clone)]
diff --git a/crates/ra_hir/src/function/scope.rs b/crates/ra_hir/src/function/scope.rs
index 3e4cfad0c..42bfe4f32 100644
--- a/crates/ra_hir/src/function/scope.rs
+++ b/crates/ra_hir/src/function/scope.rs
@@ -5,19 +5,19 @@ use ra_syntax::{
     algo::generate,
     ast::{self, ArgListOwner, LoopBodyOwner, NameOwner},
 };
+use ra_arena::{Arena, RawId, impl_arena_id};
 use ra_db::LocalSyntaxPtr;
 
-use crate::{
-    arena::{Arena, Id},
-    Name, AsName,
-};
+use crate::{Name, AsName};
 
-pub(crate) type ScopeId = Id<ScopeData>;
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ScopeId(RawId);
+impl_arena_id!(ScopeId);
 
 #[derive(Debug, PartialEq, Eq)]
 pub struct FnScopes {
     pub self_param: Option<LocalSyntaxPtr>,
-    scopes: Arena<ScopeData>,
+    scopes: Arena<ScopeId, ScopeData>,
     scope_for: FxHashMap<LocalSyntaxPtr, ScopeId>,
 }
 
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index a09dee8b1..4d6378e02 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -1,10 +1,8 @@
 use ra_db::{SourceRootId, LocationIntener, Cancelable, FileId};
 use ra_syntax::{SourceFileNode, SyntaxKind, SyntaxNode, SyntaxNodeRef, SourceFile, AstNode, ast};
+use ra_arena::{Arena, RawId, impl_arena_id};
 
-use crate::{
-    HirDatabase, PerNs, ModuleId, Module, Def, Function, Struct, Enum,
-    arena::{Arena, Id},
-};
+use crate::{HirDatabase, PerNs, ModuleId, Module, Def, Function, Struct, Enum, ImplBlock, Crate};
 
 /// hir makes a heavy use of ids: integer (u32) handlers to various things. You
 /// can think of id as a pointer (but without a lifetime) or a file descriptor
@@ -48,6 +46,13 @@ impl HirFileId {
         }
     }
 
+    pub(crate) fn as_macro_call_id(self) -> Option<MacroCallId> {
+        match self.0 {
+            HirFileIdRepr::Macro(it) => Some(it),
+            _ => None,
+        }
+    }
+
     pub(crate) fn hir_source_file(db: &impl HirDatabase, file_id: HirFileId) -> SourceFileNode {
         match file_id.0 {
             HirFileIdRepr::File(file_id) => db.source_file(file_id),
@@ -172,6 +177,18 @@ impl DefId {
         let loc = self.loc(db);
         Module::new(db, loc.source_root_id, loc.module_id)
     }
+
+    /// Returns the containing crate.
+    pub fn krate(&self, db: &impl HirDatabase) -> Cancelable<Option<Crate>> {
+        Ok(self.module(db)?.krate(db))
+    }
+
+    /// Returns the containing impl block, if this is an impl item.
+    pub fn impl_block(self, db: &impl HirDatabase) -> Cancelable<Option<ImplBlock>> {
+        let loc = self.loc(db);
+        let module_impls = db.impls_in_module(loc.source_root_id, loc.module_id)?;
+        Ok(ImplBlock::containing(module_impls, self))
+    }
 }
 
 impl DefLoc {
@@ -199,7 +216,9 @@ impl DefKind {
 
 /// Identifier of item within a specific file. This is stable over reparses, so
 /// it's OK to use it as a salsa key/value.
-pub(crate) type SourceFileItemId = Id<SyntaxNode>;
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct SourceFileItemId(RawId);
+impl_arena_id!(SourceFileItemId);
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct SourceItemId {
@@ -212,7 +231,7 @@ pub struct SourceItemId {
 #[derive(Debug, PartialEq, Eq)]
 pub struct SourceFileItems {
     file_id: HirFileId,
-    arena: Arena<SyntaxNode>,
+    arena: Arena<SourceFileItemId, SyntaxNode>,
 }
 
 impl SourceFileItems {
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
new file mode 100644
index 000000000..01afa84c4
--- /dev/null
+++ b/crates/ra_hir/src/impl_block.rs
@@ -0,0 +1,180 @@
+use std::sync::Arc;
+use rustc_hash::FxHashMap;
+
+use ra_arena::{Arena, RawId, impl_arena_id};
+use ra_syntax::ast::{self, AstNode};
+use ra_db::{LocationIntener, Cancelable, SourceRootId};
+
+use crate::{
+    DefId, DefLoc, DefKind, SourceItemId, SourceFileItems,
+    Module, Function,
+    db::HirDatabase,
+    type_ref::TypeRef,
+    module::{ModuleSourceNode, ModuleId},
+};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ImplBlock {
+    module_impl_blocks: Arc<ModuleImplBlocks>,
+    impl_id: ImplId,
+}
+
+impl ImplBlock {
+    pub(crate) fn containing(
+        module_impl_blocks: Arc<ModuleImplBlocks>,
+        def_id: DefId,
+    ) -> Option<ImplBlock> {
+        let impl_id = *module_impl_blocks.impls_by_def.get(&def_id)?;
+        Some(ImplBlock {
+            module_impl_blocks,
+            impl_id,
+        })
+    }
+
+    fn impl_data(&self) -> &ImplData {
+        &self.module_impl_blocks.impls[self.impl_id]
+    }
+
+    pub fn target_trait(&self) -> Option<&TypeRef> {
+        self.impl_data().target_trait.as_ref()
+    }
+
+    pub fn target_type(&self) -> &TypeRef {
+        &self.impl_data().target_type
+    }
+
+    pub fn items(&self) -> &[ImplItem] {
+        &self.impl_data().items
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ImplData {
+    target_trait: Option<TypeRef>,
+    target_type: TypeRef,
+    items: Vec<ImplItem>,
+}
+
+impl ImplData {
+    pub(crate) fn from_ast(
+        db: &impl AsRef<LocationIntener<DefLoc, DefId>>,
+        file_items: &SourceFileItems,
+        module: &Module,
+        node: ast::ImplBlock,
+    ) -> Self {
+        let target_trait = node.target_type().map(TypeRef::from_ast);
+        let target_type = TypeRef::from_ast_opt(node.target_type());
+        let file_id = module.source().file_id();
+        let items = if let Some(item_list) = node.item_list() {
+            item_list
+                .impl_items()
+                .map(|item_node| {
+                    let kind = match item_node {
+                        ast::ImplItem::FnDef(..) => DefKind::Function,
+                        ast::ImplItem::ConstDef(..) => DefKind::Item,
+                        ast::ImplItem::TypeDef(..) => DefKind::Item,
+                    };
+                    let item_id = file_items.id_of_unchecked(item_node.syntax());
+                    let def_loc = DefLoc {
+                        kind,
+                        source_root_id: module.source_root_id,
+                        module_id: module.module_id,
+                        source_item_id: SourceItemId {
+                            file_id,
+                            item_id: Some(item_id),
+                        },
+                    };
+                    let def_id = def_loc.id(db);
+                    match item_node {
+                        ast::ImplItem::FnDef(..) => ImplItem::Method(Function::new(def_id)),
+                        ast::ImplItem::ConstDef(..) => ImplItem::Const(def_id),
+                        ast::ImplItem::TypeDef(..) => ImplItem::Type(def_id),
+                    }
+                })
+                .collect()
+        } else {
+            Vec::new()
+        };
+        ImplData {
+            target_trait,
+            target_type,
+            items,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ImplItem {
+    Method(Function),
+    // these don't have their own types yet
+    Const(DefId),
+    Type(DefId),
+    // Existential
+}
+
+impl ImplItem {
+    pub fn def_id(&self) -> DefId {
+        match self {
+            ImplItem::Method(f) => f.def_id(),
+            ImplItem::Const(def_id) => *def_id,
+            ImplItem::Type(def_id) => *def_id,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ImplId(pub RawId);
+impl_arena_id!(ImplId);
+
+/// Collection of impl blocks is a two-step process: First we collect the blocks
+/// per-module; then we build an index of all impl blocks in the crate. This
+/// way, we avoid having to do this process for the whole crate whenever someone
+/// types in any file; as long as the impl blocks in the file don't change, we
+/// don't need to do the second step again.
+///
+/// (The second step does not yet exist currently.)
+#[derive(Debug, PartialEq, Eq)]
+pub struct ModuleImplBlocks {
+    impls: Arena<ImplId, ImplData>,
+    impls_by_def: FxHashMap<DefId, ImplId>,
+}
+
+impl ModuleImplBlocks {
+    fn new() -> Self {
+        ModuleImplBlocks {
+            impls: Arena::default(),
+            impls_by_def: FxHashMap::default(),