27 files changed, 1278 insertions, 369 deletions
diff --git a/Cargo.lock b/Cargo.lock
index 1465268b2..4f691f39e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -41,11 +41,24 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "backtrace"
-version = "0.3.30"
+version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "autocfg 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace-sys 0.1.29 (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 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "dbghelp-sys 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-demangle 0.1.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
+name = "backtrace"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "backtrace-sys 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
 "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
 "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
 "rustc-demangle 0.1.15 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -53,7 +66,7 @@ dependencies = [
 [[package]]
 name = "backtrace-sys"
-version = "0.1.28"
+version = "0.1.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -94,7 +107,7 @@ dependencies = [
 "block-padding 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
 "byte-tools 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "generic-array 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "generic-array 0.12.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -122,8 +135,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -194,12 +207,13 @@ dependencies = [
 [[package]]
 name = "chrono"
-version = "0.4.6"
+version = "0.4.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
+ "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
 "num-integer 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)",
 "num-traits 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "time 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -264,6 +278,15 @@ dependencies = [
 ]
 [[package]]
+name = "cpuprofiler"
+version = "0.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "error-chain 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
 name = "crossbeam-channel"
 version = "0.3.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -312,13 +335,22 @@ dependencies = [
 ]
 [[package]]
+name = "dbghelp-sys"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi-build 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
 name = "derive-new"
 version = "0.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.38 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -336,7 +368,7 @@ name = "digest"
 version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "generic-array 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "generic-array 0.12.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -377,10 +409,18 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "error-chain"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "backtrace 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
+name = "error-chain"
 version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "backtrace 0.3.30 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.32 (registry+https://github.com/rust-lang/crates.io-index)",
 "version_check 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -389,7 +429,7 @@ name = "failure"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "backtrace 0.3.30 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.32 (registry+https://github.com/rust-lang/crates.io-index)",
 "failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -400,7 +440,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.38 (registry+https://github.com/rust-lang/crates.io-index)",
 "synstructure 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -429,7 +469,7 @@ name = "flexi_logger"
 version = "0.13.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "chrono 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "glob 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "regex 1.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -493,13 +533,13 @@ dependencies = [
 "flexi_logger 0.13.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "lsp-types 0.57.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
 name = "generic-array"
-version = "0.12.0"
+version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "typenum 1.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -578,7 +618,7 @@ name = "insta"
 version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "chrono 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "ci_info 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "console 0.7.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "difference 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -587,7 +627,7 @@ dependencies = [
 "pest 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "pest_derive 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "ron 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_yaml 0.8.9 (registry+https://github.com/rust-lang/crates.io-index)",
 "uuid 0.7.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -672,6 +712,11 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "lazy_static"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+[[package]]
+name = "lazy_static"
 version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -714,8 +759,8 @@ dependencies = [
 "bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "num-derive 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "num-traits 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 "url 1.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "url_serde 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -820,7 +865,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.38 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -936,7 +981,7 @@ dependencies = [
 "pest_meta 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.38 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -1142,7 +1187,7 @@ dependencies = [
 "ra_vfs 0.2.5 (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)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 "tempfile 3.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "test_utils 0.1.0",
@@ -1175,7 +1220,8 @@ dependencies = [
 name = "ra_prof"
 version = "0.1.0"
 dependencies = [
- "backtrace 0.3.30 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.32 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cpuprofiler 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
 "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "once_cell 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1190,7 +1236,7 @@ dependencies = [
 "ra_db 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)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 "test_utils 0.1.0",
 "walkdir 2.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1205,7 +1251,7 @@ dependencies = [
 "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "ra_parser 0.1.0",
 "ra_text_edit 0.1.0",
- "rowan 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rowan 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "smol_str 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
 "test_utils 0.1.0",
 "text_unit 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1432,16 +1478,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "base64 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
 name = "rowan"
-version = "0.5.4"
+version = "0.5.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "colosseum 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "smol_str 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
 "text_unit 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1496,7 +1543,7 @@ dependencies = [
 "heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.38 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -1523,7 +1570,7 @@ version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -1533,20 +1580,20 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "serde"
-version = "1.0.92"
+version = "1.0.93"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
 name = "serde_derive"
-version = "1.0.92"
+version = "1.0.93"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.38 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -1556,7 +1603,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "itoa 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
 "ryu 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -1566,7 +1613,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "dtoa 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
 "linked-hash-map 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "yaml-rust 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1604,7 +1651,7 @@ name = "smol_str"
 version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -1630,7 +1677,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "syn"
-version = "0.15.36"
+version = "0.15.38"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1645,7 +1692,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.38 (registry+https://github.com/rust-lang/crates.io-index)",
 "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1667,7 +1714,7 @@ name = "tera"
 version = "0.11.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "chrono 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "error-chain 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
 "humansize 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1675,7 +1722,7 @@ dependencies = [
 "pest 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "pest_derive 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "regex 1.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 "slug 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
 "unic-segment 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1726,7 +1773,7 @@ name = "text_unit"
 version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -1884,7 +1931,7 @@ name = "url_serde"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 "url 1.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1899,7 +1946,7 @@ version = "0.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 [[package]]
@@ -1987,8 +2034,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)" = "92c7fb76bc8826a8b33b4ee5bb07a247a81e76764ab4d55e8f73e3a4d8808c71"
 "checksum atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "9a7d5b8723950951411ee34d271d99dddcc2035a16ab25310ea2c8cfd4369652"
 "checksum autocfg 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "0e49efa51329a5fd37e7c79db4621af617cd4e3e5bc224939808d076077077bf"
-"checksum backtrace 0.3.30 (registry+https://github.com/rust-lang/crates.io-index)" = "ada4c783bb7e7443c14e0480f429ae2cc99da95065aeab7ee1b81ada0419404f"
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@@ -2005,18 +2053,20 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum chalk-macros 0.1.1 (git+https://github.com/flodiebold/chalk.git?branch=fuel)" = "<none>"
 "checksum chalk-rust-ir 0.1.0 (git+https://github.com/flodiebold/chalk.git?branch=fuel)" = "<none>"
 "checksum chalk-solve 0.1.0 (git+https://github.com/flodiebold/chalk.git?branch=fuel)" = "<none>"
-"checksum chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "45912881121cb26fad7c38c17ba7daa18764771836b34fab7d3fbd93ed633878"
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 "checksum crossbeam-queue 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7c979cd6cfe72335896575c6b5688da489e420d36a27a0b9eb0c73db574b4a4b"
 "checksum crossbeam-utils 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)" = "f8306fcef4a7b563b76b7dd949ca48f52bc1141aa067d2ea09565f3e2652aa5c"
+"checksum dbghelp-sys 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "97590ba53bcb8ac28279161ca943a924d1fd4a8fb3fa63302591647c4fc5b850"
 "checksum derive-new 0.5.6 (registry+https://github.com/rust-lang/crates.io-index)" = "6ca414e896ae072546f4d789f452daaecf60ddee4c9df5dc6d5936d769e3d87c"
 "checksum deunicode 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "850878694b7933ca4c9569d30a34b55031b9b139ee1fc7b94a527c4ef960d690"
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@@ -2028,6 +2078,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum ena 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3dc01d68e08ca384955a3aeba9217102ca1aa85b6e168639bf27739f1d749d87"
 "checksum encode_unicode 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "90b2c9496c001e8cb61827acdefad780795c42264c137744cae6f7d9e3450abd"
 "checksum error-chain 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)" = "3ab49e9dcb602294bc42f9a7dfc9bc6e936fca4418ea300dbfb84fe16de0b7d9"
+"checksum error-chain 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bd5c82c815138e278b8dcdeffc49f27ea6ffb528403e9dea4194f2e3dd40b143"
 "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"
@@ -2041,7 +2092,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
 "checksum fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2e9763c69ebaae630ba35f74888db465e49e259ba1bc0eda7d06f4a067615d82"
 "checksum fuchsia-zircon-sys 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "3dcaa9ae7725d12cdb85b3ad99a434db70b468c09ded17e012d86b5c1010f7a7"
-"checksum generic-array 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3c0f28c2f5bfb5960175af447a2da7c18900693738343dc896ffbcabd9839592"
+"checksum generic-array 0.12.3 (registry+https://github.com/rust-lang/crates.io-index)" = "c68f0274ae0e023facc3c97b2e00f076be70e254bc851d972503b328db79b2ec"
 "checksum glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "8be18de09a56b60ed0edf84bc9df007e30040691af7acd1c41874faac5895bfb"
 "checksum glob 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9b919933a397b79c37e33b77bb2aa3dc8eb6e165ad809e58ff75bc7db2e34574"
 "checksum heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "20564e78d53d2bb135c343b3f47714a56af2061f1c928fdb541dc7b9fdd94205"
@@ -2062,6 +2113,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum join_to_string 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4dc7a5290e8c2606ce2be49f456d50f69173cb96d1541e4f66e34ac8b331a98f"
 "checksum kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
 "checksum lalrpop-intern 0.15.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cc4fd87be4a815fd373e02773983940f0d75fb26fde8c098e9e45f7af03154c0"
+"checksum lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "76f033c7ad61445c5b347c7382dd1237847eb1bce590fe50365dcb33d546be73"
 "checksum lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bc5729f27f159ddd61f4df6228e827e86643d4d3e7c32183cb30a1c08f604a14"
 "checksum lazycell 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b294d6fa9ee409a054354afc4352b0b9ef7ca222c69b8812cbea9e7d2bf3783f"
 "checksum libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)" = "6281b86796ba5e4366000be6e9e18bf35580adf9e63fbe2294aadb587613a319"
@@ -2121,7 +2173,7 @@ 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 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "4a83fa3702a688b9359eccba92d153ac33fd2e8462f9e0e3fdf155239ea7792e"
 "checksum ron 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "17f52a24414403f81528b67488cf8edc4eda977d3af1646bb6b106a600ead78f"
-"checksum rowan 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)" = "695dbacb8b8e077caf0cdeb65b0fe0c27bd99a9b7bf5f6467681c4c94cbe6133"
+"checksum rowan 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)" = "500ba7550373d42593a5228085bad391517378fa31ad2a84defe100dd8259fef"
 "checksum rustc-demangle 0.1.15 (registry+https://github.com/rust-lang/crates.io-index)" = "a7f4dccf6f4891ebcc0c39f9b6eb1a83b9bf5d747cb439ec6fba4f3b977038af"
 "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"
@@ -2133,8 +2185,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum scopeguard 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b42e15e59b18a828bbf5c58ea01debb36b9b096346de35d941dcb89009f24a0d"
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
 "checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
-"checksum serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)" = "32746bf0f26eab52f06af0d0aa1984f641341d06d8d673c693871da2d188c9be"
+"checksum serde 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)" = "960e29cf7004b3b6e65fc5002981400eb3ccc017a08a2406940823e58e7179a9"
-"checksum serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)" = "46a3223d0c9ba936b61c0d2e3e559e3217dbfb8d65d06d26e8b3c25de38bae3e"
+"checksum serde_derive 1.0.93 (registry+https://github.com/rust-lang/crates.io-index)" = "c4cce6663696bd38272e90bf34a0267e1226156c33f52d3f3915a2dd5d802085"
 "checksum serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)" = "5a23aa71d4a4d43fdbfaac00eff68ba8a06a51759a89ac3304323e800c4dd40d"
 "checksum serde_yaml 0.8.9 (registry+https://github.com/rust-lang/crates.io-index)" = "38b08a9a90e5260fe01c6480ec7c811606df6d3a660415808c3c3fa8ed95b582"
 "checksum sha-1 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)" = "23962131a91661d643c98940b20fcaffe62d776a823247be80a48fcb8b6fce68"
@@ -2145,7 +2197,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum stacker 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "fb79482f57cf598af52094ec4cc3b3c42499d3ce5bd426f2ac41515b7e57404b"
 "checksum strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 "checksum superslice 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ab16ced94dbd8a46c82fd81e3ed9a8727dac2977ea869d217bcc4ea1f122e81f"
-"checksum syn 0.15.36 (registry+https://github.com/rust-lang/crates.io-index)" = "8b4f551a91e2e3848aeef8751d0d4eec9489b6474c720fd4c55958d8d31a430c"
+"checksum syn 0.15.38 (registry+https://github.com/rust-lang/crates.io-index)" = "37ea458a750f59ab679b47fef9b6722c586c5742f4cfe18a120bbc807e5e01fd"
 "checksum synstructure 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)" = "02353edf96d6e4dc81aea2d8490a7e9db177bf8acb0e951c24940bf866cb313f"
 "checksum tempfile 3.0.8 (registry+https://github.com/rust-lang/crates.io-index)" = "7dc4738f2e68ed2855de5ac9cdbe05c9216773ecde4739b2f095002ab03a13ef"
 "checksum tera 0.11.20 (registry+https://github.com/rust-lang/crates.io-index)" = "4b505279e19d8f7d24b1a9dc58327c9c36174b1a2c7ebdeac70792d017cb64f3"
diff --git a/crates/ra_cli/Cargo.toml b/crates/ra_cli/Cargo.toml
index 301145b5d..b10873cd8 100644
--- a/crates/ra_cli/Cargo.toml
+++ b/crates/ra_cli/Cargo.toml
@@ -16,4 +16,7 @@ ra_ide_api = { path = "../ra_ide_api" }
 ra_batch = { path = "../ra_batch" }
 ra_hir = { path = "../ra_hir" }
 ra_db = { path = "../ra_db" }
-ra_prof = { path = "../ra_prof" }
+[dependencies.ra_prof]
+path = "../ra_prof"
+# features = [ "cpuprofiler" ]
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index d8832a9de..8f4de1c85 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -20,13 +20,41 @@ use crate::{
    lang_item::{LangItems, LangItemTarget}, type_alias::TypeAliasData,
 };
-// This database has access to source code, so queries here are not really
+/// We store all interned things in the single QueryGroup.
-// incremental.
+///
-#[salsa::query_group(AstDatabaseStorage)]
+/// This is done mainly to allow both "volatile" `AstDatabase` and "stable"
-pub trait AstDatabase: SourceDatabase {
+/// `DefDatabase` to access macros, without adding hard dependencies between the
+/// two.
+#[salsa::query_group(InternDatabaseStorage)]
+pub trait InternDatabase: SourceDatabase {
    #[salsa::interned]
    fn intern_macro(&self, macro_call: MacroCallLoc) -> ids::MacroCallId;
+    #[salsa::interned]
+    fn intern_function(&self, loc: ids::ItemLoc<ast::FnDef>) -> ids::FunctionId;
+    #[salsa::interned]
+    fn intern_struct(&self, loc: ids::ItemLoc<ast::StructDef>) -> ids::StructId;
+    #[salsa::interned]
+    fn intern_enum(&self, loc: ids::ItemLoc<ast::EnumDef>) -> ids::EnumId;
+    #[salsa::interned]
+    fn intern_const(&self, loc: ids::ItemLoc<ast::ConstDef>) -> ids::ConstId;
+    #[salsa::interned]
+    fn intern_static(&self, loc: ids::ItemLoc<ast::StaticDef>) -> ids::StaticId;
+    #[salsa::interned]
+    fn intern_trait(&self, loc: ids::ItemLoc<ast::TraitDef>) -> ids::TraitId;
+    #[salsa::interned]
+    fn intern_type_alias(&self, loc: ids::ItemLoc<ast::TypeAliasDef>) -> ids::TypeAliasId;
+    // Interned IDs for Chalk integration
+    #[salsa::interned]
+    fn intern_type_ctor(&self, type_ctor: TypeCtor) -> ids::TypeCtorId;
+    #[salsa::interned]
+    fn intern_impl_block(&self, impl_block: ImplBlock) -> ids::GlobalImplId;
+}
+/// This database has access to source code, so queries here are not really
+/// incremental.
+#[salsa::query_group(AstDatabaseStorage)]
+pub trait AstDatabase: InternDatabase {
    #[salsa::invoke(crate::source_id::AstIdMap::ast_id_map_query)]
    fn ast_id_map(&self, file_id: HirFileId) -> Arc<AstIdMap>;
    #[salsa::transparent]
@@ -40,7 +68,6 @@ pub trait AstDatabase: SourceDatabase {
    #[salsa::invoke(crate::ids::macro_def_query)]
    fn macro_def(&self, macro_id: MacroDefId) -> Option<Arc<mbe::MacroRules>>;
    #[salsa::invoke(crate::ids::macro_arg_query)]
    fn macro_arg(&self, macro_call: ids::MacroCallId) -> Option<Arc<tt::Subtree>>;
@@ -51,28 +78,7 @@ pub trait AstDatabase: SourceDatabase {
 // This database uses `AstDatabase` internally,
 #[salsa::query_group(DefDatabaseStorage)]
 #[salsa::requires(AstDatabase)]
-pub trait DefDatabase: SourceDatabase {
+pub trait DefDatabase: InternDatabase {
-    #[salsa::interned]
-    fn intern_function(&self, loc: ids::ItemLoc<ast::FnDef>) -> ids::FunctionId;
-    #[salsa::interned]
-    fn intern_struct(&self, loc: ids::ItemLoc<ast::StructDef>) -> ids::StructId;
-    #[salsa::interned]
-    fn intern_enum(&self, loc: ids::ItemLoc<ast::EnumDef>) -> ids::EnumId;
-    #[salsa::interned]
-    fn intern_const(&self, loc: ids::ItemLoc<ast::ConstDef>) -> ids::ConstId;
-    #[salsa::interned]
-    fn intern_static(&self, loc: ids::ItemLoc<ast::StaticDef>) -> ids::StaticId;
-    #[salsa::interned]
-    fn intern_trait(&self, loc: ids::ItemLoc<ast::TraitDef>) -> ids::TraitId;
-    #[salsa::interned]
-    fn intern_type_alias(&self, loc: ids::ItemLoc<ast::TypeAliasDef>) -> ids::TypeAliasId;
-    // Interned IDs for Chalk integration
-    #[salsa::interned]
-    fn intern_type_ctor(&self, type_ctor: TypeCtor) -> ids::TypeCtorId;
-    #[salsa::interned]
-    fn intern_impl_block(&self, impl_block: ImplBlock) -> ids::GlobalImplId;
    #[salsa::invoke(crate::adt::StructData::struct_data_query)]
    fn struct_data(&self, s: Struct) -> Arc<StructData>;
@@ -181,6 +187,26 @@ pub trait HirDatabase: DefDatabase + AstDatabase {
    #[salsa::volatile]
    fn solver(&self, krate: Crate) -> Arc<Mutex<crate::ty::traits::Solver>>;
+    #[salsa::invoke(crate::ty::traits::chalk::associated_ty_data_query)]
+    fn associated_ty_data(&self, id: chalk_ir::TypeId) -> Arc<chalk_rust_ir::AssociatedTyDatum>;
+    #[salsa::invoke(crate::ty::traits::chalk::trait_datum_query)]
+    fn trait_datum(
+        &self,
+        krate: Crate,
+        trait_id: chalk_ir::TraitId,
+    ) -> Arc<chalk_rust_ir::TraitDatum>;
+    #[salsa::invoke(crate::ty::traits::chalk::struct_datum_query)]
+    fn struct_datum(
+        &self,
+        krate: Crate,
+        struct_id: chalk_ir::StructId,
+    ) -> Arc<chalk_rust_ir::StructDatum>;
+    #[salsa::invoke(crate::ty::traits::chalk::impl_datum_query)]
+    fn impl_datum(&self, krate: Crate, impl_id: chalk_ir::ImplId) -> Arc<chalk_rust_ir::ImplDatum>;
    #[salsa::invoke(crate::ty::traits::implements_query)]
    fn implements(
        &self,
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 033af1632..b7215ac03 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -9,7 +9,7 @@ use ra_prof::profile;
 use mbe::MacroRules;
 use crate::{
-    Module, DefDatabase, AstId, FileAstId, AstDatabase, Source,
+    Module, DefDatabase, AstId, FileAstId, AstDatabase, Source, InternDatabase,
 };
 /// hir makes heavy use of ids: integer (u32) handlers to various things. You
@@ -37,7 +37,7 @@ pub struct HirFileId(HirFileIdRepr);
 impl HirFileId {
    /// For macro-expansion files, returns the file original source file the
    /// expansion originated from.
-    pub fn original_file(self, db: &impl AstDatabase) -> FileId {
+    pub fn original_file(self, db: &impl InternDatabase) -> FileId {
        match self.0 {
            HirFileIdRepr::File(file_id) => file_id,
            HirFileIdRepr::Macro(macro_file) => {
@@ -187,7 +187,7 @@ pub struct MacroCallLoc {
 }
 impl MacroCallId {
-    pub(crate) fn loc(self, db: &impl AstDatabase) -> MacroCallLoc {
+    pub(crate) fn loc(self, db: &impl InternDatabase) -> MacroCallLoc {
        db.lookup_intern_macro(self)
    }
@@ -198,7 +198,7 @@ impl MacroCallId {
 }
 impl MacroCallLoc {
-    pub(crate) fn id(self, db: &impl AstDatabase) -> MacroCallId {
+    pub(crate) fn id(self, db: &impl InternDatabase) -> MacroCallId {
        db.intern_macro(self)
    }
 }
@@ -235,10 +235,13 @@ pub(crate) struct LocationCtx<DB> {
    file_id: HirFileId,
 }
-impl<'a, DB: DefDatabase + AstDatabase> LocationCtx<&'a DB> {
+impl<'a, DB: DefDatabase> LocationCtx<&'a DB> {
    pub(crate) fn new(db: &'a DB, module: Module, file_id: HirFileId) -> LocationCtx<&'a DB> {
        LocationCtx { db, module, file_id }
    }
+}
+impl<'a, DB: DefDatabase + AstDatabase> LocationCtx<&'a DB> {
    pub(crate) fn to_def<N, DEF>(self, ast: &N) -> DEF
    where
        N: AstNode,
@@ -257,10 +260,7 @@ pub(crate) trait AstItemDef<N: AstNode>: salsa::InternKey + Clone {
        let item_id = items.ast_id(ast);
        Self::from_ast_id(ctx, item_id)
    }
-    fn from_ast_id(
+    fn from_ast_id(ctx: LocationCtx<&impl DefDatabase>, ast_id: FileAstId<N>) -> Self {
-        ctx: LocationCtx<&(impl AstDatabase + DefDatabase)>,
-        ast_id: FileAstId<N>,
-    ) -> Self {
        let loc = ItemLoc { module: ctx.module, ast_id: ast_id.with_file_id(ctx.file_id) };
        Self::intern(ctx.db, loc)
    }
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index f07a36926..5afd846f5 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -47,7 +47,7 @@ mod code_model;
 mod marks;
 use crate::{
-    db::{AstDatabase, DefDatabase, HirDatabase},
+    db::{InternDatabase, AstDatabase, DefDatabase, HirDatabase},
    name::{AsName, KnownName},
    source_id::{FileAstId, AstId},
    resolve::Resolver,
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 5d38ac76c..c57dfbf01 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -15,6 +15,7 @@ pub const WORKSPACE: SourceRootId = SourceRootId(0);
 #[salsa::database(
    ra_db::SourceDatabaseStorage,
+    db::InternDatabaseStorage,
    db::AstDatabaseStorage,
    db::DefDatabaseStorage,
    db::HirDatabaseStorage
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 3532faf01..f4ca454e4 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -231,7 +231,9 @@ fn or(left: ItemOrMacro, right: ItemOrMacro) -> ItemOrMacro {
 impl CrateDefMap {
    pub(crate) fn crate_def_map_query(
-        db: &(impl DefDatabase + AstDatabase),
+        // Note that this doesn't have `+ AstDatabase`!
+        // This gurantess that `CrateDefMap` is stable across reparses.
+        db: &impl DefDatabase,
        krate: Crate,
    ) -> Arc<CrateDefMap> {
        let _p = profile("crate_def_map_query");
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index b74dc33b1..ef4d1ed70 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -7,7 +7,7 @@ use ra_syntax::ast;
 use crate::{
    Function, Module, Struct, Union, Enum, Const, Static, Trait, TypeAlias, MacroDef,
-    DefDatabase, HirFileId, Name, Path, AstDatabase,
+    DefDatabase, HirFileId, Name, Path,
    KnownName, AstId,
    nameres::{
        Resolution, PerNs, ModuleDef, ReachedFixedPoint, ResolveMode,
@@ -19,10 +19,7 @@ use crate::{
    either::Either,
 };
-pub(super) fn collect_defs(
+pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> CrateDefMap {
-    db: &(impl DefDatabase + AstDatabase),
-    mut def_map: CrateDefMap,
-) -> CrateDefMap {
    // populate external prelude
    for dep in def_map.krate.dependencies(db) {
        log::debug!("crate dep {:?} -> {:?}", dep.name, dep.krate);
@@ -95,7 +92,7 @@ struct DefCollector<DB> {
 impl<'a, DB> DefCollector<&'a DB>
 where
-    DB: DefDatabase + AstDatabase,
+    DB: DefDatabase,
 {
    fn collect(&mut self) {
        let crate_graph = self.db.crate_graph();
@@ -465,7 +462,7 @@ where
            ModCollector { def_collector: &mut *self, file_id, module_id, raw_items: &raw_items }
                .collect(raw_items.items());
        } else {
-            log::error!("Too deep macro expansion: {}", macro_call_id.debug_dump(self.db));
+            log::error!("Too deep macro expansion: {:?}", macro_call_id);
            self.def_map.poison_macros.insert(macro_def_id);
        }
@@ -487,7 +484,7 @@ struct ModCollector<'a, D> {
 impl<DB> ModCollector<'_, &'_ mut DefCollector<&'_ DB>>
 where
-    DB: DefDatabase + AstDatabase,
+    DB: DefDatabase,
 {
    fn collect(&mut self, items: &[raw::RawItem]) {
        for item in items {
@@ -632,7 +629,7 @@ fn is_macro_rules(path: &Path) -> bool {
 }
 fn resolve_submodule(
-    db: &(impl DefDatabase + AstDatabase),
+    db: &impl DefDatabase,
    file_id: HirFileId,
    name: &Name,
    is_root: bool,
@@ -675,7 +672,7 @@ mod tests {
    use rustc_hash::FxHashSet;
    fn do_collect_defs(
-        db: &(impl DefDatabase + AstDatabase),
+        db: &impl DefDatabase,
        def_map: CrateDefMap,
        monitor: MacroStackMonitor,
    ) -> CrateDefMap {
diff --git a/crates/ra_hir/src/ty/traits.rs b/crates/ra_hir/src/ty/traits.rs
index 9a6349d4b..69c03a36c 100644
--- a/crates/ra_hir/src/ty/traits.rs
+++ b/crates/ra_hir/src/ty/traits.rs
@@ -12,7 +12,7 @@ use super::{TraitRef, Ty, Canonical, ProjectionTy};
 use self::chalk::{ToChalk, from_chalk};
-mod chalk;
+pub(crate) mod chalk;
 pub(crate) type Solver = chalk_solve::Solver;
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 5105588ee..4ceb8b70b 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -10,7 +10,7 @@ use test_utils::tested_by;
 use ra_db::salsa::{InternId, InternKey};
 use crate::{
-    Trait, HasGenericParams, ImplBlock,
+    Trait, HasGenericParams, ImplBlock, Crate,
    db::HirDatabase,
    ty::{TraitRef, Ty, ApplicationTy, TypeCtor, Substs, GenericPredicate, CallableDef, ProjectionTy},
    ty::display::HirDisplay,
@@ -256,204 +256,16 @@ where
    DB: HirDatabase,
 {
    fn associated_ty_data(&self, id: TypeId) -> Arc<AssociatedTyDatum> {
-        debug!("associated_ty_data {:?}", id);
+        self.db.associated_ty_data(id)
-        let type_alias: TypeAlias = from_chalk(self.db, id);
-        let trait_ = match type_alias.container(self.db) {
-            Some(crate::Container::Trait(t)) => t,
-            _ => panic!("associated type not in trait"),
-        };
-        let generic_params = type_alias.generic_params(self.db);
-        let parameter_kinds = generic_params
-            .params_including_parent()
-            .into_iter()
-            .map(|p| chalk_ir::ParameterKind::Ty(lalrpop_intern::intern(&p.name.to_string())))
-            .collect();
-        let datum = AssociatedTyDatum {
-            trait_id: trait_.to_chalk(self.db),
-            id,
-            name: lalrpop_intern::intern(&type_alias.name(self.db).to_string()),
-            parameter_kinds,
-            // FIXME add bounds and where clauses
-            bounds: vec![],
-            where_clauses: vec![],
-        };
-        Arc::new(datum)
    }
    fn trait_datum(&self, trait_id: chalk_ir::TraitId) -> Arc<TraitDatum> {
-        debug!("trait_datum {:?}", trait_id);
+        self.db.trait_datum(self.krate, trait_id)
-        if trait_id == UNKNOWN_TRAIT {
-            let trait_datum_bound = chalk_rust_ir::TraitDatumBound {
-                trait_ref: chalk_ir::TraitRef {
-                    trait_id: UNKNOWN_TRAIT,
-                    parameters: vec![chalk_ir::Ty::BoundVar(0).cast()],
-                },
-                associated_ty_ids: Vec::new(),
-                where_clauses: Vec::new(),
-                flags: chalk_rust_ir::TraitFlags {
-                    auto: false,
-                    marker: false,
-                    upstream: true,
-                    fundamental: false,
-                },
-            };
-            return Arc::new(TraitDatum { binders: make_binders(trait_datum_bound, 1) });
-        }
-        let trait_: Trait = from_chalk(self.db, trait_id);
-        debug!("trait {:?} = {:?}", trait_id, trait_.name(self.db));
-        let generic_params = trait_.generic_params(self.db);
-        let bound_vars = Substs::bound_vars(&generic_params);
-        let trait_ref = trait_.trait_ref(self.db).subst(&bound_vars).to_chalk(self.db);
-        let flags = chalk_rust_ir::TraitFlags {
-            auto: trait_.is_auto(self.db),
-            upstream: trait_.module(self.db).krate(self.db) != Some(self.krate),
-            // FIXME set these flags correctly
-            marker: false,
-            fundamental: false,
-        };
-        let where_clauses = convert_where_clauses(self.db, trait_.into(), &bound_vars);
-        let associated_ty_ids = trait_
-            .items(self.db)
-            .into_iter()
-            .filter_map(|trait_item| match trait_item {
-                crate::traits::TraitItem::TypeAlias(type_alias) => Some(type_alias),
-                _ => None,
-            })
-            .map(|type_alias| type_alias.to_chalk(self.db))
-            .collect();
-        let trait_datum_bound =
-            chalk_rust_ir::TraitDatumBound { trait_ref, where_clauses, flags, associated_ty_ids };
-        let trait_datum = TraitDatum { binders: make_binders(trait_datum_bound, bound_vars.len()) };
-        Arc::new(trait_datum)
    }
    fn struct_datum(&self, struct_id: chalk_ir::StructId) -> Arc<StructDatum> {
-        debug!("struct_datum {:?}", struct_id);
+        self.db.struct_datum(self.krate, struct_id)
-        let type_ctor = from_chalk(self.db, struct_id);
-        debug!("struct {:?} = {:?}", struct_id, type_ctor);
-        // FIXME might be nicer if we can create a fake GenericParams for the TypeCtor
-        // FIXME extract this to a method on Ty
-        let (num_params, where_clauses, upstream) = match type_ctor {
-            TypeCtor::Bool
-            | TypeCtor::Char
-            | TypeCtor::Int(_)
-            | TypeCtor::Float(_)
-            | TypeCtor::Never
-            | TypeCtor::Str => (0, vec![], true),
-            TypeCtor::Slice | TypeCtor::Array | TypeCtor::RawPtr(_) | TypeCtor::Ref(_) => {
-                (1, vec![], true)
-            }
-            TypeCtor::FnPtr { num_args } => (num_args as usize + 1, vec![], true),
-            TypeCtor::Tuple { cardinality } => (cardinality as usize, vec![], true),
-            TypeCtor::FnDef(callable) => {
-                tested_by!(trait_resolution_on_fn_type);
-                let krate = match callable {
-                    CallableDef::Function(f) => f.module(self.db).krate(self.db),
-                    CallableDef::Struct(s) => s.module(self.db).krate(self.db),
-                    CallableDef::EnumVariant(v) => {
-                        v.parent_enum(self.db).module(self.db).krate(self.db)
-                    }
-                };
-                let generic_def: GenericDef = match callable {
-                    CallableDef::Function(f) => f.into(),
-                    CallableDef::Struct(s) => s.into(),
-                    CallableDef::EnumVariant(v) => v.parent_enum(self.db).into(),
-                };
-                let generic_params = generic_def.generic_params(self.db);
-                let bound_vars = Substs::bound_vars(&generic_params);
-                let where_clauses = convert_where_clauses(self.db, generic_def, &bound_vars);
-                (
-                    generic_params.count_params_including_parent(),
-                    where_clauses,
-                    krate != Some(self.krate),
-                )
-            }
-            TypeCtor::Adt(adt) => {
-                let generic_params = adt.generic_params(self.db);
-                let bound_vars = Substs::bound_vars(&generic_params);
-                let where_clauses = convert_where_clauses(self.db, adt.into(), &bound_vars);
-                (
-                    generic_params.count_params_including_parent(),
-                    where_clauses,
-                    adt.krate(self.db) != Some(self.krate),
-                )
-            }
-        };
-        let flags = chalk_rust_ir::StructFlags {
-            upstream,
-            // FIXME set fundamental flag correctly
-            fundamental: false,
-        };
-        let self_ty = chalk_ir::ApplicationTy {
-            name: TypeName::TypeKindId(type_ctor.to_chalk(self.db).into()),
-            parameters: (0..num_params).map(|i| chalk_ir::Ty::BoundVar(i).cast()).collect(),
-        };
-        let struct_datum_bound = chalk_rust_ir::StructDatumBound {
-            self_ty,
-            fields: Vec::new(), // FIXME add fields (only relevant for auto traits)
-            where_clauses,
-            flags,
-        };
-        let struct_datum = StructDatum { binders: make_binders(struct_datum_bound, num_params) };
-        Arc::new(struct_datum)
    }
    fn impl_datum(&self, impl_id: ImplId) -> Arc<ImplDatum> {
-        debug!("impl_datum {:?}", impl_id);
+        self.db.impl_datum(self.krate, impl_id)
-        let impl_block: ImplBlock = from_chalk(self.db, impl_id);
-        let generic_params = impl_block.generic_params(self.db);
-        let bound_vars = Substs::bound_vars(&generic_params);
-        let trait_ref = impl_block
-            .target_trait_ref(self.db)
-            .expect("FIXME handle unresolved impl block trait ref")
-            .subst(&bound_vars);
-        let impl_type = if impl_block.module().krate(self.db) == Some(self.krate) {
-            chalk_rust_ir::ImplType::Local
-        } else {
-            chalk_rust_ir::ImplType::External
-        };
-        let where_clauses = convert_where_clauses(self.db, impl_block.into(), &bound_vars);
-        let negative = impl_block.is_negative(self.db);
-        debug!(
-            "impl {:?}: {}{} where {:?}",
-            impl_id,
-            if negative { "!" } else { "" },
-            trait_ref.display(self.db),
-            where_clauses
-        );
-        let trait_ = trait_ref.trait_;
-        let trait_ref = trait_ref.to_chalk(self.db);
-        let associated_ty_values = impl_block
-            .items(self.db)
-            .into_iter()
-            .filter_map(|item| match item {
-                ImplItem::TypeAlias(t) => Some(t),
-                _ => None,
-            })
-            .filter_map(|t| {
-                let assoc_ty = trait_.associated_type_by_name(self.db, t.name(self.db))?;
-                let ty = self.db.type_for_def(t.into(), crate::Namespace::Types).subst(&bound_vars);
-                Some(chalk_rust_ir::AssociatedTyValue {
-                    impl_id,
-                    associated_ty_id: assoc_ty.to_chalk(self.db),
-                    value: chalk_ir::Binders {
-                        value: chalk_rust_ir::AssociatedTyValueBound { ty: ty.to_chalk(self.db) },
-                        binders: vec![], // we don't support GATs yet
-                    },
-                })
-            })
-            .collect();
-        let impl_datum_bound = chalk_rust_ir::ImplDatumBound {
-            trait_ref: if negative {
-                chalk_rust_ir::PolarizedTraitRef::Negative(trait_ref)
-            } else {
-                chalk_rust_ir::PolarizedTraitRef::Positive(trait_ref)
-            },
-            where_clauses,
-            associated_ty_values,
-            impl_type,
-        };
-        debug!("impl_datum: {:?}", impl_datum_bound);
-        let impl_datum = ImplDatum { binders: make_binders(impl_datum_bound, bound_vars.len()) };
-        Arc::new(impl_datum)
    }
    fn impls_for_trait(&self, trait_id: chalk_ir::TraitId) -> Vec<ImplId> {
        debug!("impls_for_trait {:?}", trait_id);
@@ -503,6 +315,220 @@ where
    }
 }
+pub(crate) fn associated_ty_data_query(
+    db: &impl HirDatabase,
+    id: TypeId,
+) -> Arc<AssociatedTyDatum> {
+    debug!("associated_ty_data {:?}", id);
+    let type_alias: TypeAlias = from_chalk(db, id);
+    let trait_ = match type_alias.container(db) {
+        Some(crate::Container::Trait(t)) => t,
+        _ => panic!("associated type not in trait"),
+    };
+    let generic_params = type_alias.generic_params(db);
+    let parameter_kinds = generic_params
+        .params_including_parent()
+        .into_iter()
+        .map(|p| chalk_ir::ParameterKind::Ty(lalrpop_intern::intern(&p.name.to_string())))
+        .collect();
+    let datum = AssociatedTyDatum {
+        trait_id: trait_.to_chalk(db),
+        id,
+        name: lalrpop_intern::intern(&type_alias.name(db).to_string()),
+        parameter_kinds,
+        // FIXME add bounds and where clauses
+        bounds: vec![],
+        where_clauses: vec![],
+    };
+    Arc::new(datum)
+}
+pub(crate) fn trait_datum_query(
+    db: &impl HirDatabase,
+    krate: Crate,
+    trait_id: chalk_ir::TraitId,
+) -> Arc<TraitDatum> {
+    debug!("trait_datum {:?}", trait_id);
+    if trait_id == UNKNOWN_TRAIT {
+        let trait_datum_bound = chalk_rust_ir::TraitDatumBound {
+            trait_ref: chalk_ir::TraitRef {
+                trait_id: UNKNOWN_TRAIT,
+                parameters: vec![chalk_ir::Ty::BoundVar(0).cast()],
+            },
+            associated_ty_ids: Vec::new(),
+            where_clauses: Vec::new(),
+            flags: chalk_rust_ir::TraitFlags {
+                auto: false,
+                marker: false,
+                upstream: true,
+                fundamental: false,
+            },
+        };
+        return Arc::new(TraitDatum { binders: make_binders(trait_datum_bound, 1) });
+    }
+    let trait_: Trait = from_chalk(db, trait_id);
+    debug!("trait {:?} = {:?}", trait_id, trait_.name(db));
+    let generic_params = trait_.generic_params(db);
+    let bound_vars = Substs::bound_vars(&generic_params);
+    let trait_ref = trait_.trait_ref(db).subst(&bound_vars).to_chalk(db);
+    let flags = chalk_rust_ir::TraitFlags {
+        auto: trait_.is_auto(db),
+        upstream: trait_.module(db).krate(db) != Some(krate),
+        // FIXME set these flags correctly
+        marker: false,
+        fundamental: false,
+    };
+    let where_clauses = convert_where_clauses(db, trait_.into(), &bound_vars);
+    let associated_ty_ids = trait_
+        .items(db)
+        .into_iter()
+        .filter_map(|trait_item| match trait_item {
+            crate::traits::TraitItem::TypeAlias(type_alias) => Some(type_alias),
+            _ => None,
+        })
+        .map(|type_alias| type_alias.to_chalk(db))
+        .collect();
+    let trait_datum_bound =
+        chalk_rust_ir::TraitDatumBound { trait_ref, where_clauses, flags, associated_ty_ids };
+    let trait_datum = TraitDatum { binders: make_binders(trait_datum_bound, bound_vars.len()) };
+    Arc::new(trait_datum)
+}
+pub(crate) fn struct_datum_query(
+    db: &impl HirDatabase,
+    krate: Crate,
+    struct_id: chalk_ir::StructId,
+) -> Arc<StructDatum> {
+    debug!("struct_datum {:?}", struct_id);
+    let type_ctor = from_chalk(db, struct_id);
+    debug!("struct {:?} = {:?}", struct_id, type_ctor);
+    // FIXME might be nicer if we can create a fake GenericParams for the TypeCtor
+    // FIXME extract this to a method on Ty
+    let (num_params, where_clauses, upstream) = match type_ctor {
+        TypeCtor::Bool
+        | TypeCtor::Char
+        | TypeCtor::Int(_)
+        | TypeCtor::Float(_)
+        | TypeCtor::Never
+        | TypeCtor::Str => (0, vec![], true),
+        TypeCtor::Slice | TypeCtor::Array | TypeCtor::RawPtr(_) | TypeCtor::Ref(_) => {
+            (1, vec![], true)
+        }
+        TypeCtor::FnPtr { num_args } => (num_args as usize + 1, vec![], true),
+        TypeCtor::Tuple { cardinality } => (cardinality as usize, vec![], true),
+        TypeCtor::FnDef(callable) => {
+            tested_by!(trait_resolution_on_fn_type);
+            let upstream = match callable {
+                CallableDef::Function(f) => f.module(db).krate(db),
+                CallableDef::Struct(s) => s.module(db).krate(db),
+                CallableDef::EnumVariant(v) => v.parent_enum(db).module(db).krate(db),
+            } != Some(krate);
+            let generic_def: GenericDef = match callable {
+                CallableDef::Function(f) => f.into(),
+                CallableDef::Struct(s) => s.into(),
+                CallableDef::EnumVariant(v) => v.parent_enum(db).into(),
+            };
+            let generic_params = generic_def.generic_params(db);
+            let bound_vars = Substs::bound_vars(&generic_params);
+            let where_clauses = convert_where_clauses(db, generic_def, &bound_vars);
+            (generic_params.count_params_including_parent(), where_clauses, upstream)
+        }
+        TypeCtor::Adt(adt) => {
+            let generic_params = adt.generic_params(db);
+            let bound_vars = Substs::bound_vars(&generic_params);
+            let where_clauses = convert_where_clauses(db, adt.into(), &bound_vars);
+            (
+                generic_params.count_params_including_parent(),
+                where_clauses,
+                adt.krate(db) != Some(krate),
+            )
+        }
+    };
+    let flags = chalk_rust_ir::StructFlags {
+        upstream,
+        // FIXME set fundamental flag correctly
+        fundamental: false,
+    };
+    let self_ty = chalk_ir::ApplicationTy {
+        name: TypeName::TypeKindId(type_ctor.to_chalk(db).into()),
+        parameters: (0..num_params).map(|i| chalk_ir::Ty::BoundVar(i).cast()).collect(),
+    };
+    let struct_datum_bound = chalk_rust_ir::StructDatumBound {
+        self_ty,
+        fields: Vec::new(), // FIXME add fields (only relevant for auto traits)
+        where_clauses,
+        flags,
+    };
+    let struct_datum = StructDatum { binders: make_binders(struct_datum_bound, num_params) };
+    Arc::new(struct_datum)
+}
+pub(crate) fn impl_datum_query(
+    db: &impl HirDatabase,
+    krate: Crate,
+    impl_id: ImplId,
+) -> Arc<ImplDatum> {
+    let _p = ra_prof::profile("impl_datum");
+    debug!("impl_datum {:?}", impl_id);
+    let impl_block: ImplBlock = from_chalk(db, impl_id);
+    let generic_params = impl_block.generic_params(db);
+    let bound_vars = Substs::bound_vars(&generic_params);
+    let trait_ref = impl_block
+        .target_trait_ref(db)
+        .expect("FIXME handle unresolved impl block trait ref")
+        .subst(&bound_vars);
+    let impl_type = if impl_block.module().krate(db) == Some(krate) {
+        chalk_rust_ir::ImplType::Local
+    } else {
+        chalk_rust_ir::ImplType::External
+    };
+    let where_clauses = convert_where_clauses(db, impl_block.into(), &bound_vars);
+    let negative = impl_block.is_negative(db);
+    debug!(
+        "impl {:?}: {}{} where {:?}",
+        impl_id,
+        if negative { "!" } else { "" },
+        trait_ref.display(db),
+        where_clauses
+    );
+    let trait_ = trait_ref.trait_;
+    let trait_ref = trait_ref.to_chalk(db);
+    let associated_ty_values = impl_block
+        .items(db)
+        .into_iter()
+        .filter_map(|item| match item {
+            ImplItem::TypeAlias(t) => Some(t),
+            _ => None,
+        })
+        .filter_map(|t| {
+            let assoc_ty = trait_.associated_type_by_name(db, t.name(db))?;
+            let ty = db.type_for_def(t.into(), crate::Namespace::Types).subst(&bound_vars);
+            Some(chalk_rust_ir::AssociatedTyValue {
+                impl_id,
+                associated_ty_id: assoc_ty.to_chalk(db),
+                value: chalk_ir::Binders {
+                    value: chalk_rust_ir::AssociatedTyValueBound { ty: ty.to_chalk(db) },
+                    binders: vec![], // we don't support GATs yet
+                },
+            })
+        })
+        .collect();
+    let impl_datum_bound = chalk_rust_ir::ImplDatumBound {
+        trait_ref: if negative {
+            chalk_rust_ir::PolarizedTraitRef::Negative(trait_ref)
+        } else {
+            chalk_rust_ir::PolarizedTraitRef::Positive(trait_ref)
+        },
+        where_clauses,
+        associated_ty_values,
+        impl_type,
+    };
+    debug!("impl_datum: {:?}", impl_datum_bound);
+    let impl_datum = ImplDatum { binders: make_binders(impl_datum_bound, bound_vars.len()) };
+    Arc::new(impl_datum)
+}
 fn id_from_chalk<T: InternKey>(chalk_id: chalk_ir::RawId) -> T {
    T::from_intern_id(InternId::from(chalk_id.index))
 }
diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index 82b061419..cb7d30c43 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -14,6 +14,7 @@ use crate::{LineIndex, symbol_index::{self, SymbolsDatabase}};
    ra_db::SourceDatabaseStorage,
    LineIndexDatabaseStorage,
    symbol_index::SymbolsDatabaseStorage,
+    hir::db::InternDatabaseStorage,
    hir::db::AstDatabaseStorage,
    hir::db::DefDatabaseStorage,
    hir::db::HirDatabaseStorage
diff --git a/crates/ra_lsp_server/src/main_loop/handlers.rs b/crates/ra_lsp_server/src/main_loop/handlers.rs
index 6373240d5..47222cd0a 100644
--- a/crates/ra_lsp_server/src/main_loop/handlers.rs
+++ b/crates/ra_lsp_server/src/main_loop/handlers.rs
@@ -621,17 +621,32 @@ pub fn handle_formatting(
    let output = rustfmt.wait_with_output()?;
    let captured_stdout = String::from_utf8(output.stdout)?;
    if !output.status.success() {
-        return Err(LspError::new(
+        match output.status.code() {
-            -32900,
+            Some(1) => {
-            format!(
+                // While `rustfmt` doesn't have a specific exit code for parse errors this is the
-                r#"rustfmt exited with:
+                // likely cause exiting with 1. Most Language Servers swallow parse errors on
-            Status: {}
+                // formatting because otherwise an error is surfaced to the user on top of the
-            stdout: {}"#,
+                // syntax error diagnostics they're already receiving. This is especially jarring
-                output.status, captured_stdout,
+                // if they have format on save enabled.
-            ),
+                log::info!("rustfmt exited with status 1, assuming parse error and ignoring");
-        )
+                return Ok(None);
-        .into());
+            }
+            _ => {
+                // Something else happened - e.g. `rustfmt` is missing or caught a signal
+                return Err(LspError::new(
+                    -32900,
+                    format!(
+                        r#"rustfmt exited with:
+                           Status: {}
+                           stdout: {}"#,
+                        output.status, captured_stdout,
+                    ),
+                )
+                .into());
+            }
+        }
    }
    Ok(Some(vec![TextEdit {
diff --git a/crates/ra_prof/Cargo.toml b/crates/ra_prof/Cargo.toml
index d55af18f5..787e18385 100644
--- a/crates/ra_prof/Cargo.toml
+++ b/crates/ra_prof/Cargo.toml
@@ -9,3 +9,4 @@ publish = false
 once_cell = "0.2.0"
 itertools = "0.8.0"
 backtrace = "0.3.28"
+cpuprofiler = { version = "0.0.3", optional = true }
diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
index de67b4031..1e8d780ab 100644
--- a/crates/ra_prof/src/lib.rs
+++ b/crates/ra_prof/src/lib.rs
@@ -255,6 +255,39 @@ impl Drop for Scope {
    }
 }
+/// A wrapper around https://github.com/AtheMathmo/cpuprofiler
+///
+/// It can be used to capture sampling profiles of sections of code.
+/// It is not exactly out-of-the-box, as it relies on gperftools.
+/// See the docs for the crate for more!
+#[derive(Debug)]
+pub struct CpuProfiler {
+    _private: (),
+}
+pub fn cpu_profiler() -> CpuProfiler {
+    #[cfg(feature = "cpuprofiler")]
+    {
+        cpuprofiler::PROFILER.lock().unwrap().start("./out.profile").unwrap();
+    }
+    #[cfg(not(feature = "cpuprofiler"))]
+    {
+        eprintln!("cpuprofiler feature is disabled")
+    }
+    CpuProfiler { _private: () }
+}
+impl Drop for CpuProfiler {
+    fn drop(&mut self) {
+        #[cfg(feature = "cpuprofiler")]
+        {
+            cpuprofiler::PROFILER.lock().unwrap().stop().unwrap();
+        }
+    }
+}
 #[cfg(test)]
 mod tests {
    use super::*;
diff --git a/docs/dev/README.md b/docs/dev/README.md
index 3dc37e86e..0a148ed32 100644
--- a/docs/dev/README.md
+++ b/docs/dev/README.md
@@ -97,6 +97,25 @@ To work on the VS Code extension, launch code inside `editors/code` and use `F5`
 to launch/debug. To automatically apply formatter and linter suggestions, use
 `npm run fix`.
+Tests are located inside `src/test` and are named `*.test.ts`. They use the
+[Mocha](https://mochajs.org) test framework and the builtin Node
+[assert](https://nodejs.org/api/assert.html) module. Unlike normal Node tests
+they must be hosted inside a VS Code instance. This can be done in one of two
+ways:
+1. When `F5` debugging in VS Code select the `Extension Tests` configuration
+   from the drop-down at the top of the Debug View. This will launch a temporary
+   instance of VS Code. The test results will appear in the "Debug Console" tab
+   of the primary VS Code instance.
+2. Run `npm test` from the command line. Although this is initiated from the
+   command line it is not headless; it will also launch a temporary instance of
+   VS Code. 
+Due to the requirements of running the tests inside VS Code they are **not run
+on CI**. When making changes to the extension please ensure the tests are not
+broken locally before opening a Pull Request.
 # Logging
 Logging is done by both rust-analyzer and VS Code, so it might be tricky to
diff --git a/editors/code/.vscode/launch.json b/editors/code/.vscode/launch.json
index b9d14dddd..c3578f476 100644
--- a/editors/code/.vscode/launch.json
+++ b/editors/code/.vscode/launch.json
@@ -20,6 +20,7 @@
            "request": "launch",
            "runtimeExecutable": "${execPath}",
            "args": [
+                "${workspaceFolder}/src/test/",
                "--extensionDevelopmentPath=${workspaceFolder}",
                "--extensionTestsPath=${workspaceFolder}/out/test"
            ],
diff --git a/editors/code/package.json b/editors/code/package.json
index ac2ba82e3..6e2dd0494 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -23,6 +23,7 @@
        "postinstall": "node ./node_modules/vscode/bin/install",
        "fix": "prettier **/*.{json,ts} --write && tslint --project . --fix",
        "lint": "tslint --project .",
+        "test": "node node_modules/vscode/bin/test",
        "prettier": "prettier **/*.{json,ts}",
        "travis": "npm run compile && npm run lint && npm run prettier -- --list-different"
    },
diff --git a/editors/code/src/commands/cargo_watch.ts b/editors/code/src/commands/cargo_watch.ts
index 126a8b1b3..1ec5f8d5f 100644
--- a/editors/code/src/commands/cargo_watch.ts
+++ b/editors/code/src/commands/cargo_watch.ts
@@ -2,12 +2,17 @@ import * as child_process from 'child_process';
 import * as fs from 'fs';
 import * as path from 'path';
 import * as vscode from 'vscode';
 import { Server } from '../server';
 import { terminate } from '../utils/processes';
 import {
    mapRustDiagnosticToVsCode,
    RustDiagnostic
 } from '../utils/rust_diagnostics';
+import {
+    areCodeActionsEqual,
+    areDiagnosticsEqual
+} from '../utils/vscode_diagnostics';
 import { LineBuffer } from './line_buffer';
 import { StatusDisplay } from './watch_status';
@@ -184,67 +189,6 @@ export class CargoWatchProvider
            this.statusDisplay.hide();
        }
-        function areDiagnosticsEqual(
-            left: vscode.Diagnostic,
-            right: vscode.Diagnostic
-        ): boolean {
-            return (
-                left.source === right.source &&
-                left.severity === right.severity &&
-                left.range.isEqual(right.range) &&
-                left.message === right.message
-            );
-        }
-        function areCodeActionsEqual(
-            left: vscode.CodeAction,
-            right: vscode.CodeAction
-        ): boolean {
-            if (
-                left.kind !== right.kind ||
-                left.title !== right.title ||
-                !left.edit ||
-                !right.edit
-            ) {
-                return false;
-            }
-            const leftEditEntries = left.edit.entries();
-            const rightEditEntries = right.edit.entries();
-            if (leftEditEntries.length !== rightEditEntries.length) {
-                return false;
-            }
-            for (let i = 0; i < leftEditEntries.length; i++) {
-                const [leftUri, leftEdits] = leftEditEntries[i];
-                const [rightUri, rightEdits] = rightEditEntries[i];
-                if (leftUri.toString() !== rightUri.toString()) {
-                    return false;
-                }
-                if (leftEdits.length !== rightEdits.length) {
-                    return false;
-                }
-                for (let j = 0; j < leftEdits.length; j++) {
-                    const leftEdit = leftEdits[j];
-                    const rightEdit = rightEdits[j];
-                    if (!leftEdit.range.isEqual(rightEdit.range)) {
-                        return false;
-                    }
-                    if (leftEdit.newText !== rightEdit.newText) {
-                        return false;
-                    }
-                }
-            }
-            return true;
-        }
        interface CargoArtifact {
            reason: string;
            package_id: string;
diff --git a/editors/code/src/test/fixtures/rust-diagnostics/clippy/trivially_copy_pass_by_ref.json b/editors/code/src/test/fixtures/rust-diagnostics/clippy/trivially_copy_pass_by_ref.json
new file mode 100644
index 000000000..d874e99bc
--- /dev/null
+++ b/editors/code/src/test/fixtures/rust-diagnostics/clippy/trivially_copy_pass_by_ref.json
@@ -0,0 +1,110 @@
+{
+    "message": "this argument is passed by reference, but would be more efficient if passed by value",
+    "code": {
+        "code": "clippy::trivially_copy_pass_by_ref",
+        "explanation": null
+    },
+    "level": "warning",
+    "spans": [
+        {
+            "file_name": "compiler/mir/tagset.rs",
+            "byte_start": 941,
+            "byte_end": 946,
+            "line_start": 42,
+            "line_end": 42,
+            "column_start": 24,
+            "column_end": 29,
+            "is_primary": true,
+            "text": [
+                {
+                    "text": "    pub fn is_disjoint(&self, other: Self) -> bool {",
+                    "highlight_start": 24,
+                    "highlight_end": 29
+                }
+            ],
+            "label": null,
+            "suggested_replacement": null,
+            "suggestion_applicability": null,
+            "expansion": null
+        }
+    ],
+    "children": [
+        {
+            "message": "lint level defined here",
+            "code": null,
+            "level": "note",
+            "spans": [
+                {
+                    "file_name": "compiler/lib.rs",
+                    "byte_start": 8,
+                    "byte_end": 19,
+                    "line_start": 1,
+                    "line_end": 1,
+                    "column_start": 9,
+                    "column_end": 20,
+                    "is_primary": true,
+                    "text": [
+                        {
+                            "text": "#![warn(clippy::all)]",
+                            "highlight_start": 9,
+                            "highlight_end": 20
+                        }
+                    ],
+                    "label": null,
+                    "suggested_replacement": null,
+                    "suggestion_applicability": null,
+                    "expansion": null
+                }
+            ],
+            "children": [],
+            "rendered": null
+        },
+        {
+            "message": "#[warn(clippy::trivially_copy_pass_by_ref)] implied by #[warn(clippy::all)]",
+            "code": null,
+            "level": "note",
+            "spans": [],
+            "children": [],
+            "rendered": null
+        },
+        {
+            "message": "for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#trivially_copy_pass_by_ref",
+            "code": null,
+            "level": "help",
+            "spans": [],
+            "children": [],
+            "rendered": null
+        },
+        {
+            "message": "consider passing by value instead",
+            "code": null,
+            "level": "help",
+            "spans": [
+                {
+                    "file_name": "compiler/mir/tagset.rs",
+                    "byte_start": 941,
+                    "byte_end": 946,
+                    "line_start": 42,
+                    "line_end": 42,
+                    "column_start": 24,
+                    "column_end": 29,
+                    "is_primary": true,
+                    "text": [
+                        {
+                            "text": "    pub fn is_disjoint(&self, other: Self) -> bool {",
+                            "highlight_start": 24,
+                            "highlight_end": 29
+                        }
+                    ],
+                    "label": null,
+                    "suggested_replacement": "self",
+                    "suggestion_applicability": "Unspecified",
+                    "expansion": null
+                }
+            ],
+            "children": [],
+            "rendered": null
+        }
+    ],
+    "rendered": "warning: this argument is passed by reference, but would be more efficient if passed by value\n  --> compiler/mir/tagset.rs:42:24\n   |\n42 |     pub fn is_disjoint(&self, other: Self) -> bool {\n   |                        ^^^^^ help: consider passing by value instead: `self`\n   |\nnote: lint level defined here\n  --> compiler/lib.rs:1:9\n   |\n1  | #![warn(clippy::all)]\n   |         ^^^^^^^^^^^\n   = note: #[warn(clippy::trivially_copy_pass_by_ref)] implied by #[warn(clippy::all)]\n   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#trivially_copy_pass_by_ref\n\n"
+}
diff --git a/editors/code/src/test/fixtures/rust-diagnostics/error/E0053.json b/editors/code/src/test/fixtures/rust-diagnostics/error/E0053.json
new file mode 100644
index 000000000..ea5c976d1
--- /dev/null
+++ b/editors/code/src/test/fixtures/rust-diagnostics/error/E0053.json
@@ -0,0 +1,42 @@
+{
+    "message": "method `next` has an incompatible type for trait",
+    "code": {
+        "code": "E0053",
+        "explanation": "\nThe parameters of any trait method must match between a trait implementation\nand the trait definition.\n\nHere are a couple examples of this error:\n\n```compile_fail,E0053\ntrait Foo {\n    fn foo(x: u16);\n    fn bar(&self);\n}\n\nstruct Bar;\n\nimpl Foo for Bar {\n    // error, expected u16, found i16\n    fn foo(x: i16) { }\n\n    // error, types differ in mutability\n    fn bar(&mut self) { }\n}\n```\n"
+    },
+    "level": "error",
+    "spans": [
+        {
+            "file_name": "compiler/ty/list_iter.rs",
+            "byte_start": 1307,
+            "byte_end": 1350,
+            "line_start": 52,
+            "line_end": 52,
+            "column_start": 5,
+            "column_end": 48,
+            "is_primary": true,
+            "text": [
+                {
+                    "text": "    fn next(&self) -> Option<&'list ty::Ref<M>> {",
+                    "highlight_start": 5,
+                    "highlight_end": 48
+                }
+            ],
+            "label": "types differ in mutability",
+            "suggested_replacement": null,
+            "suggestion_applicability": null,
+            "expansion": null
+        }
+    ],
+    "children": [
+        {
+            "message": "expected type `fn(&mut ty::list_iter::ListIterator<'list, M>) -> std::option::Option<&ty::Ref<M>>`\n   found type `fn(&ty::list_iter::ListIterator<'list, M>) -> std::option::Option<&'list ty::Ref<M>>`",
+            "code": null,
+            "level": "note",
+            "spans": [],
+            "children": [],
+            "rendered": null
+        }
+    ],
+    "rendered": "error[E0053]: method `next` has an incompatible type for trait\n  --> compiler/ty/list_iter.rs:52:5\n   |\n52 |     fn next(&self) -> Option<&'list ty::Ref<M>> {\n   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ types differ in mutability\n   |\n   = note: expected type `fn(&mut ty::list_iter::ListIterator<'list, M>) -> std::option::Option<&ty::Ref<M>>`\n              found type `fn(&ty::list_iter::ListIterator<'list, M>) -> std::option::Option<&'list ty::Ref<M>>`\n\n"
+}
diff --git a/editors/code/src/test/fixtures/rust-diagnostics/error/E0061.json b/editors/code/src/test/fixtures/rust-diagnostics/error/E0061.json
new file mode 100644
index 000000000..3154d1098
--- /dev/null
+++ b/editors/code/src/test/fixtures/rust-diagnostics/error/E0061.json
@@ -0,0 +1,114 @@
+{
+    "message": "this function takes 2 parameters but 3 parameters were supplied",
+    "code": {
+        "code": "E0061",
+        "explanation": "\nThe number of arguments passed to a function must match the number of arguments\nspecified in the function signature.\n\nFor example, a function like:\n\n```\nfn f(a: u16, b: &str) {}\n```\n\nMust always be called with exactly two arguments, e.g., `f(2, \"test\")`.\n\nNote that Rust does not have a notion of optional function arguments or\nvariadic functions (except for its C-FFI).\n"
+    },
+    "level": "error",
+    "spans": [
+        {
+            "file_name": "compiler/ty/select.rs",
+            "byte_start": 8787,
+            "byte_end": 9241,
+            "line_start": 219,
+            "line_end": 231,
+            "column_start": 5,
+            "column_end": 6,
+            "is_primary": false,
+            "text": [
+                {
+                    "text": "    pub fn add_evidence(",
+                    "highlight_start": 5,
+                    "highlight_end": 25
+                },
+                {
+                    "text": "        &mut self,",
+                    "highlight_start": 1,
+                    "highlight_end": 19
+                },
+                {
+                    "text": "        target_poly: &ty::Ref<ty::Poly>,",
+                    "highlight_start": 1,
+                    "highlight_end": 41
+                },
+                {
+                    "text": "        evidence_poly: &ty::Ref<ty::Poly>,",
+                    "highlight_start": 1,
+                    "highlight_end": 43
+                },
+                {
+                    "text": "    ) {",
+                    "highlight_start": 1,
+                    "highlight_end": 8
+                },
+                {
+                    "text": "        match target_poly {",
+                    "highlight_start": 1,
+                    "highlight_end": 28
+                },
+                {
+                    "text": "            ty::Ref::Var(tvar, _) => self.add_var_evidence(tvar, evidence_poly),",
+                    "highlight_start": 1,
+                    "highlight_end": 81
+                },
+                {
+                    "text": "            ty::Ref::Fixed(target_ty) => {",
+                    "highlight_start": 1,
+                    "highlight_end": 43
+                },
+                {
+                    "text": "                let evidence_ty = evidence_poly.resolve_to_ty();",
+                    "highlight_start": 1,
+                    "highlight_end": 65
+                },
+                {
+                    "text": "                self.add_evidence_ty(target_ty, evidence_poly, evidence_ty)",
+                    "highlight_start": 1,
+                    "highlight_end": 76
+                },
+                {
+                    "text": "            }",
+                    "highlight_start": 1,
+                    "highlight_end": 14
+                },
+                {
+                    "text": "        }",
+                    "highlight_start": 1,
+                    "highlight_end": 10
+                },
+                {
+                    "text": "    }",
+                    "highlight_start": 1,
+                    "highlight_end": 6
+                }
+            ],
+            "label": "defined here",
+            "suggested_replacement": null,
+            "suggestion_applicability": null,
+            "expansion": null
+        },
+        {
+            "file_name": "compiler/ty/select.rs",
+            "byte_start": 4045,
+            "byte_end": 4057,
+            "line_start": 104,
+            "line_end": 104,
+            "column_start": 18,
+            "column_end": 30,
+            "is_primary": true,
+            "text": [
+                {
+                    "text": "            self.add_evidence(target_fixed, evidence_fixed, false);",
+                    "highlight_start": 18,
+                    "highlight_end": 30
+                }
+            ],
+            "label": "expected 2 parameters",
+            "suggested_replacement": null,
+            "suggestion_applicability": null,
+            "expansion": null
+        }
+    ],
+    "children": [],
+    "rendered": "error[E0061]: this function takes 2 parameters but 3 parameters were supplied\n   --> compiler/ty/select.rs:104:18\n    |\n104 |               self.add_evidence(target_fixed, evidence_fixed, false);\n    |                    ^^^^^^^^^^^^ expected 2 parameters\n...\n219 | /     pub fn add_evidence(\n220 | |         &mut self,\n221 | |         target_poly: &ty::Ref<ty::Poly>,\n222 | |         evidence_poly: &ty::Ref<ty::Poly>,\n...   |\n230 | |         }\n231 | |     }\n    | |_____- defined here\n\n"
+}
diff --git a/editors/code/src/test/fixtures/rust-diagnostics/warning/unused_variables.json b/editors/code/src/test/fixtures/rust-diagnostics/warning/unused_variables.json
new file mode 100644
index 000000000..d1e2be722
--- /dev/null
+++ b/editors/code/src/test/fixtures/rust-diagnostics/warning/unused_variables.json
@@ -0,0 +1,72 @@
+{
+    "message": "unused variable: `foo`",
+    "code": {
+        "code": "unused_variables",
+        "explanation": null
+    },
+    "level": "warning",
+    "spans": [
+        {
+            "file_name": "driver/subcommand/repl.rs",
+            "byte_start": 9228,
+            "byte_end": 9231,
+            "line_start": 291,
+            "line_end": 291,
+            "column_start": 9,
+            "column_end": 12,
+            "is_primary": true,
+            "text": [
+                {
+                    "text": "    let foo = 42;",
+                    "highlight_start": 9,
+                    "highlight_end": 12
+                }
+            ],
+            "label": null,
+            "suggested_replacement": null,
+            "suggestion_applicability": null,
+            "expansion": null
+        }
+    ],
+    "children": [
+        {
+            "message": "#[warn(unused_variables)] on by default",
+            "code": null,
+            "level": "note",
+            "spans": [],
+            "children": [],
+            "rendered": null
+        },
+        {
+            "message": "consider prefixing with an underscore",
+            "code": null,
+            "level": "help",
+            "spans": [
+                {
+                    "file_name": "driver/subcommand/repl.rs",
+                    "byte_start": 9228,
+                    "byte_end": 9231,
+                    "line_start": 291,
+                    "line_end": 291,
+                    "column_start": 9,
+                    "column_end": 12,
+                    "is_primary": true,
+                    "text": [
+                        {
+                            "text": "    let foo = 42;",
+                            "highlight_start": 9,
+                            "highlight_end": 12
+                        }
+                    ],
+                    "label": null,
+                    "suggested_replacement": "_foo",
+                    "suggestion_applicability": "MachineApplicable",
+                    "expansion": null
+                }
+            ],
+            "children": [],
+            "rendered": null
+        }
+    ],
+    "rendered": "warning: unused variable: `foo`\n   --> driver/subcommand/repl.rs:291:9\n    |\n291 |     let foo = 42;\n    |         ^^^ help: consider prefixing with an underscore: `_foo`\n    |\n    = note: #[warn(unused_variables)] on by default\n\n"
+}
diff --git a/editors/code/src/test/index.ts b/editors/code/src/test/index.ts
new file mode 100644
index 000000000..6e565c254
--- /dev/null
+++ b/editors/code/src/test/index.ts
@@ -0,0 +1,22 @@
+//
+// PLEASE DO NOT MODIFY / DELETE UNLESS YOU KNOW WHAT YOU ARE DOING
+//
+// This file is providing the test runner to use when running extension tests.
+// By default the test runner in use is Mocha based.
+//
+// You can provide your own test runner if you want to override it by exporting
+// a function run(testRoot: string, clb: (error:Error) => void) that the extension
+// host can call to run the tests. The test runner is expected to use console.log
+// to report the results back to the caller. When the tests are finished, return
+// a possible error to the callback or null if none.
+import * as testRunner from 'vscode/lib/testrunner';
+// You can directly control Mocha options by uncommenting the following lines
+// See https://github.com/mochajs/mocha/wiki/Using-mocha-programmatically#set-options for more info
+testRunner.configure({
+    ui: 'bdd', // the TDD UI is being used in extension.test.ts (suite, test, etc.)
+    useColors: true // colored output from test results
+});
+module.exports = testRunner;
diff --git a/editors/code/src/test/rust_diagnostics.test.ts b/editors/code/src/test/rust_diagnostics.test.ts
new file mode 100644
index 000000000..f27c58fe2
--- /dev/null
+++ b/editors/code/src/test/rust_diagnostics.test.ts
@@ -0,0 +1,162 @@
+import * as assert from 'assert';
+import * as fs from 'fs';
+import * as vscode from 'vscode';
+import {
+    MappedRustDiagnostic,
+    mapRustDiagnosticToVsCode,
+    RustDiagnostic
+} from '../utils/rust_diagnostics';
+function loadDiagnosticFixture(name: string): RustDiagnostic {
+    const jsonText = fs
+        .readFileSync(
+            // We're actually in our JavaScript output directory, climb out
+            `${__dirname}/../../src/test/fixtures/rust-diagnostics/${name}.json`
+        )
+        .toString();
+    return JSON.parse(jsonText);
+}
+function mapFixtureToVsCode(name: string): MappedRustDiagnostic {
+    const rd = loadDiagnosticFixture(name);
+    const mapResult = mapRustDiagnosticToVsCode(rd);
+    if (!mapResult) {
+        return assert.fail('Mapping unexpectedly failed');
+    }
+    return mapResult;
+}
+describe('mapRustDiagnosticToVsCode', () => {
+    it('should map an incompatible type for trait error', () => {
+        const { diagnostic, codeActions } = mapFixtureToVsCode('error/E0053');
+        assert.strictEqual(
+            diagnostic.severity,
+            vscode.DiagnosticSeverity.Error
+        );
+        assert.strictEqual(diagnostic.source, 'rustc');
+        assert.strictEqual(
+            diagnostic.message,
+            [
+                `method \`next\` has an incompatible type for trait`,
+                `expected type \`fn(&mut ty::list_iter::ListIterator<'list, M>) -> std::option::Option<&ty::Ref<M>>\``,
+                `   found type \`fn(&ty::list_iter::ListIterator<'list, M>) -> std::option::Option<&'list ty::Ref<M>>\``
+            ].join('\n')
+        );
+        assert.strictEqual(diagnostic.code, 'E0053');
+        assert.strictEqual(diagnostic.tags, undefined);
+        // No related information
+        assert.deepStrictEqual(diagnostic.relatedInformation, []);
+        // There are no code actions available
+        assert.strictEqual(codeActions.length, 0);
+    });
+    it('should map an unused variable warning', () => {
+        const { diagnostic, codeActions } = mapFixtureToVsCode(
+            'warning/unused_variables'
+        );
+        assert.strictEqual(
+            diagnostic.severity,
+            vscode.DiagnosticSeverity.Warning
+        );
+        assert.strictEqual(
+            diagnostic.message,
+            [
+                'unused variable: `foo`',
+                '#[warn(unused_variables)] on by default'
+            ].join('\n')
+        );
+        assert.strictEqual(diagnostic.code, 'unused_variables');
+        assert.strictEqual(diagnostic.source, 'rustc');
+        assert.deepStrictEqual(diagnostic.tags, [
+            vscode.DiagnosticTag.Unnecessary
+        ]);
+        // No related information
+        assert.deepStrictEqual(diagnostic.relatedInformation, []);
+        // One code action available to prefix the variable
+        assert.strictEqual(codeActions.length, 1);
+        const [codeAction] = codeActions;
+        assert.strictEqual(
+            codeAction.title,
+            'consider prefixing with an underscore: `_foo`'
+        );
+        assert(codeAction.isPreferred);
+    });
+    it('should map a wrong number of parameters error', () => {
+        const { diagnostic, codeActions } = mapFixtureToVsCode('error/E0061');
+        assert.strictEqual(
+            diagnostic.severity,
+            vscode.DiagnosticSeverity.Error
+        );
+        assert.strictEqual(
+            diagnostic.message,
+            'this function takes 2 parameters but 3 parameters were supplied'
+        );
+        assert.strictEqual(diagnostic.code, 'E0061');
+        assert.strictEqual(diagnostic.source, 'rustc');
+        assert.strictEqual(diagnostic.tags, undefined);
+        // One related information for the original definition
+        const relatedInformation = diagnostic.relatedInformation;
+        if (!relatedInformation) {
+            return assert.fail('Related information unexpectedly undefined');
+        }
+        assert.strictEqual(relatedInformation.length, 1);
+        const [related] = relatedInformation;
+        assert.strictEqual(related.message, 'defined here');
+        // There are no actions available
+        assert.strictEqual(codeActions.length, 0);
+    });
+    it('should map a Clippy copy pass by ref warning', () => {
+        const { diagnostic, codeActions } = mapFixtureToVsCode(
+            'clippy/trivially_copy_pass_by_ref'
+        );
+        assert.strictEqual(
+            diagnostic.severity,
+            vscode.DiagnosticSeverity.Warning
+        );
+        assert.strictEqual(diagnostic.source, 'clippy');
+        assert.strictEqual(
+            diagnostic.message,
+            [
+                'this argument is passed by reference, but would be more efficient if passed by value',
+                '#[warn(clippy::trivially_copy_pass_by_ref)] implied by #[warn(clippy::all)]',
+                'for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#trivially_copy_pass_by_ref'
+            ].join('\n')
+        );
+        assert.strictEqual(diagnostic.code, 'trivially_copy_pass_by_ref');
+        assert.strictEqual(diagnostic.tags, undefined);
+        // One related information for the lint definition
+        const relatedInformation = diagnostic.relatedInformation;
+        if (!relatedInformation) {
+            return assert.fail('Related information unexpectedly undefined');
+        }
+        assert.strictEqual(relatedInformation.length, 1);
+        const [related] = relatedInformation;
+        assert.strictEqual(related.message, 'lint level defined here');
+        // One code action available to pass by value
+        assert.strictEqual(codeActions.length, 1);
+        const [codeAction] = codeActions;
+        assert.strictEqual(
+            codeAction.title,
+            'consider passing by value instead: `self`'
+        );
+        // Clippy does not mark this as machine applicable
+        assert.strictEqual(codeAction.isPreferred, false);
+    });
+});
diff --git a/editors/code/src/test/vscode_diagnostics.test.ts b/editors/code/src/test/vscode_diagnostics.test.ts
new file mode 100644
index 000000000..9c5d812fa
--- /dev/null
+++ b/editors/code/src/test/vscode_diagnostics.test.ts
@@ -0,0 +1,182 @@
+import * as assert from 'assert';
+import * as vscode from 'vscode';
+import {
+    areCodeActionsEqual,
+    areDiagnosticsEqual
+} from '../utils/vscode_diagnostics';
+const uri = vscode.Uri.file('/file/1');
+const range1 = new vscode.Range(
+    new vscode.Position(1, 2),
+    new vscode.Position(3, 4)
+);
+const range2 = new vscode.Range(
+    new vscode.Position(5, 6),
+    new vscode.Position(7, 8)
+);
+describe('areDiagnosticsEqual', () => {
+    it('should treat identical diagnostics as equal', () => {
+        const diagnostic1 = new vscode.Diagnostic(
+            range1,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        const diagnostic2 = new vscode.Diagnostic(
+            range1,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        assert(areDiagnosticsEqual(diagnostic1, diagnostic2));
+    });
+    it('should treat diagnostics with different sources as inequal', () => {
+        const diagnostic1 = new vscode.Diagnostic(
+            range1,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        diagnostic1.source = 'rustc';
+        const diagnostic2 = new vscode.Diagnostic(
+            range1,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        diagnostic2.source = 'clippy';
+        assert(!areDiagnosticsEqual(diagnostic1, diagnostic2));
+    });
+    it('should treat diagnostics with different ranges as inequal', () => {
+        const diagnostic1 = new vscode.Diagnostic(
+            range1,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        const diagnostic2 = new vscode.Diagnostic(
+            range2,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        assert(!areDiagnosticsEqual(diagnostic1, diagnostic2));
+    });
+    it('should treat diagnostics with different messages as inequal', () => {
+        const diagnostic1 = new vscode.Diagnostic(
+            range1,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        const diagnostic2 = new vscode.Diagnostic(
+            range1,
+            'Goodbye!, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        assert(!areDiagnosticsEqual(diagnostic1, diagnostic2));
+    });
+    it('should treat diagnostics with different severities as inequal', () => {
+        const diagnostic1 = new vscode.Diagnostic(
+            range1,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Warning
+        );
+        const diagnostic2 = new vscode.Diagnostic(
+            range1,
+            'Hello, world!',
+            vscode.DiagnosticSeverity.Error
+        );
+        assert(!areDiagnosticsEqual(diagnostic1, diagnostic2));
+    });
+});
+describe('areCodeActionsEqual', () => {
+    it('should treat identical actions as equal', () => {
+        const codeAction1 = new vscode.CodeAction(
+            'Fix me!',
+            vscode.CodeActionKind.QuickFix
+        );
+        const codeAction2 = new vscode.CodeAction(
+            'Fix me!',
+            vscode.CodeActionKind.QuickFix
+        );
+        const edit = new vscode.WorkspaceEdit();
+        edit.replace(uri, range1, 'Replace with this');
+        codeAction1.edit = edit;
+        codeAction2.edit = edit;
+        assert(areCodeActionsEqual(codeAction1, codeAction2));
+    });
+    it('should treat actions with different types as inequal', () => {
+        const codeAction1 = new vscode.CodeAction(
+            'Fix me!',
+            vscode.CodeActionKind.Refactor
+        );
+        const codeAction2 = new vscode.CodeAction(
+            'Fix me!',
+            vscode.CodeActionKind.QuickFix
+        );
+        const edit = new vscode.WorkspaceEdit();
+        edit.replace(uri, range1, 'Replace with this');
+        codeAction1.edit = edit;
+        codeAction2.edit = edit;
+        assert(!areCodeActionsEqual(codeAction1, codeAction2));
+    });
+    it('should treat actions with different titles as inequal', () => {
+        const codeAction1 = new vscode.CodeAction(
+            'Fix me!',
+            vscode.CodeActionKind.Refactor
+        );
+        const codeAction2 = new vscode.CodeAction(
+            'Do something different!',
+            vscode.CodeActionKind.Refactor
+        );
+        const edit = new vscode.WorkspaceEdit();
+        edit.replace(uri, range1, 'Replace with this');
+        codeAction1.edit = edit;
+        codeAction2.edit = edit;
+        assert(!areCodeActionsEqual(codeAction1, codeAction2));
+    });
+    it('should treat actions with different edits as inequal', () => {
+        const codeAction1 = new vscode.CodeAction(
+            'Fix me!',
+            vscode.CodeActionKind.Refactor
+        );
+        const edit1 = new vscode.WorkspaceEdit();
+        edit1.replace(uri, range1, 'Replace with this');
+        codeAction1.edit = edit1;
+        const codeAction2 = new vscode.CodeAction(
+            'Fix me!',
+            vscode.CodeActionKind.Refactor
+        );
+        const edit2 = new vscode.WorkspaceEdit();
+        edit2.replace(uri, range1, 'Replace with this other thing');
+        codeAction2.edit = edit2;
+        assert(!areCodeActionsEqual(codeAction1, codeAction2));
+    });
+});
diff --git a/editors/code/src/utils/rust_diagnostics.ts b/editors/code/src/utils/rust_diagnostics.ts
index ed049c95e..3c524cb37 100644
--- a/editors/code/src/utils/rust_diagnostics.ts
+++ b/editors/code/src/utils/rust_diagnostics.ts
@@ -187,8 +187,18 @@ export function mapRustDiagnosticToVsCode(
    const vd = new vscode.Diagnostic(location.range, rd.message, severity);
-    vd.source = 'rustc';
+    let source = 'rustc';
-    vd.code = rd.code ? rd.code.code : undefined;
+    let code = rd.code && rd.code.code;
+    if (code) {
+        // See if this is an RFC #2103 scoped lint (e.g. from Clippy)
+        const scopedCode = code.split('::');
+        if (scopedCode.length === 2) {
+            [source, code] = scopedCode;
+        }
+    }
+    vd.source = source;
+    vd.code = code;
    vd.relatedInformation = [];
    for (const secondarySpan of secondarySpans) {
diff --git a/editors/code/src/utils/vscode_diagnostics.ts b/editors/code/src/utils/vscode_diagnostics.ts
new file mode 100644
index 000000000..9d763c8d6
--- /dev/null
+++ b/editors/code/src/utils/vscode_diagnostics.ts
@@ -0,0 +1,73 @@
+import * as vscode from 'vscode';
+/** Compares two `vscode.Diagnostic`s for equality */
+export function areDiagnosticsEqual(
+    left: vscode.Diagnostic,
+    right: vscode.Diagnostic
+): boolean {
+    return (
+        left.source === right.source &&
+        left.severity === right.severity &&
+        left.range.isEqual(right.range) &&
+        left.message === right.message
+    );
+}
+/** Compares two `vscode.TextEdit`s for equality */
+function areTextEditsEqual(
+    left: vscode.TextEdit,
+    right: vscode.TextEdit
+): boolean {
+    if (!left.range.isEqual(right.range)) {
+        return false;
+    }
+    if (left.newText !== right.newText) {
+        return false;
+    }
+    return true;
+}
+/** Compares two `vscode.CodeAction`s for equality */
+export function areCodeActionsEqual(
+    left: vscode.CodeAction,
+    right: vscode.CodeAction
+): boolean {
+    if (
+        left.kind !== right.kind ||
+        left.title !== right.title ||
+        !left.edit ||
+        !right.edit
+    ) {
+        return false;
+    }
+    const leftEditEntries = left.edit.entries();
+    const rightEditEntries = right.edit.entries();
+    if (leftEditEntries.length !== rightEditEntries.length) {
+        return false;
+    }
+    for (let i = 0; i < leftEditEntries.length; i++) {
+        const [leftUri, leftEdits] = leftEditEntries[i];
+        const [rightUri, rightEdits] = rightEditEntries[i];
+        if (leftUri.toString() !== rightUri.toString()) {
+            return false;
+        }
+        if (leftEdits.length !== rightEdits.length) {
+            return false;
+        }
+        for (let j = 0; j < leftEdits.length; j++) {
+            if (!areTextEditsEqual(leftEdits[j], rightEdits[j])) {
+                return false;
+            }
+        }
+    }
+    return true;
+}