443 files changed, 26819 insertions, 17921 deletions

diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 3f52f31f8..29ac89549 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -20,7 +20,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-latest]
+        os: [ubuntu-16.04, windows-latest, macos-latest]
 
     steps:
     - name: Checkout repository
@@ -42,25 +42,25 @@ jobs:
         override: true
 
     - name: Install Nodejs
-      if: matrix.os == 'ubuntu-latest'
+      if: matrix.os == 'ubuntu-16.04'
       uses: actions/setup-node@v1
       with:
         node-version: 12.x
 
     - name: Dist
-      if: matrix.os == 'ubuntu-latest' && github.ref == 'refs/heads/release'
+      if: matrix.os == 'ubuntu-16.04' && github.ref == 'refs/heads/release'
       run: cargo xtask dist --client 0.2.$GITHUB_RUN_NUMBER
 
     - name: Dist
-      if: matrix.os == 'ubuntu-latest' && github.ref != 'refs/heads/release'
+      if: matrix.os == 'ubuntu-16.04' && github.ref != 'refs/heads/release'
       run: cargo xtask dist --nightly --client 0.3.$GITHUB_RUN_NUMBER-nightly
 
     - name: Dist
-      if: matrix.os != 'ubuntu-latest'
+      if: matrix.os != 'ubuntu-16.04'
       run: cargo xtask dist
 
     - name: Nightly analysis-stats check
-      if: matrix.os == 'ubuntu-latest' && github.ref != 'refs/heads/release'
+      if: matrix.os == 'ubuntu-16.04' && github.ref != 'refs/heads/release'
       run: ./dist/rust-analyzer-linux analysis-stats .
 
     - name: Upload artifacts
@@ -71,7 +71,7 @@ jobs:
 
   publish:
     name: publish
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-16.04
     needs: ['dist']
     steps:
     - name: Install Nodejs
@@ -94,7 +94,7 @@ jobs:
         path: dist
     - uses: actions/download-artifact@v1
       with:
-        name: dist-ubuntu-latest
+        name: dist-ubuntu-16.04
         path: dist
     - uses: actions/download-artifact@v1
       with:
diff --git a/Cargo.lock b/Cargo.lock
index 85ea4f178..c06236692 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,6 +1,15 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
 [[package]]
+name = "addr2line"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a49806b9dadc843c61e7c97e72490ad7f7220ae249012fbda9ad0609457c0543"
+dependencies = [
+ "gimli",
+]
+
+[[package]]
 name = "aho-corasick"
 version = "0.7.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -11,9 +20,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.28"
+version = "1.0.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d9a60d744a80c30fcb657dfe2c1b22bcb3e814c1a1e3674f32bf5820b570fbff"
+checksum = "85bb70cc08ec97ca5450e6eba421deeea5f172c0fc61f78b5357b2a8e8be195f"
 
 [[package]]
 name = "anymap"
@@ -46,31 +55,22 @@ checksum = "f8aac770f1885fd7e387acedd76065302551364496e46b3dd00860b2f8359b9d"
 
 [[package]]
 name = "backtrace"
-version = "0.3.46"
+version = "0.3.48"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b1e692897359247cc6bb902933361652380af0f1b7651ae5c5013407f30e109e"
+checksum = "0df2f85c8a2abbe3b7d7e748052fdd9b76a0458fdeb16ad4223f5eca78c7c130"
 dependencies = [
- "backtrace-sys",
+ "addr2line",
  "cfg-if",
  "libc",
+ "object",
  "rustc-demangle",
 ]
 
 [[package]]
-name = "backtrace-sys"
-version = "0.1.37"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "18fbebbe1c9d1f383a9cc7e8ccdb471b91c8d024ee9c2ca5b5346121fe8b4399"
-dependencies = [
- "cc",
- "libc",
-]
-
-[[package]]
 name = "base64"
-version = "0.12.0"
+version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7d5ca2cd0adc3f48f9e9ea5a6bbdf9ccc0bfade884847e484d452414c7ccffb3"
+checksum = "53d1ccbaf7d9ec9537465a97bf19edc1a4e158ecb49fc16178202238c569cc42"
 
 [[package]]
 name = "bitflags"
@@ -80,18 +80,18 @@ checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
 [[package]]
 name = "bstr"
-version = "0.2.12"
+version = "0.2.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2889e6d50f394968c8bf4240dc3f2a7eb4680844d27308f798229ac9d4725f41"
+checksum = "31accafdb70df7871592c058eca3985b71104e15ac32f64706022c58867da931"
 dependencies = [
  "memchr",
 ]
 
 [[package]]
 name = "cargo_metadata"
-version = "0.9.1"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "46e3374c604fb39d1a2f35ed5e4a4e30e60d01fab49446e08f1b3e9a90aef202"
+checksum = "b8de60b887edf6d74370fc8eb177040da4847d971d6234c7b13a6da324ef0caf"
 dependencies = [
  "semver",
  "serde",
@@ -101,9 +101,9 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.0.52"
+version = "1.0.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c3d87b23d6a92cd03af510a5ade527033f6aa6fa92161e2d5863a907d4c5e31d"
+checksum = "404b1fe4f65288577753b17e3b36a04596ee784493ec249bf81c7f2d2acd751c"
 
 [[package]]
 name = "cfg-if"
@@ -113,8 +113,8 @@ checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
 [[package]]
 name = "chalk-derive"
-version = "0.1.0"
-source = "git+https://github.com/rust-lang/chalk.git?rev=2c072cc830d04af5f10b390e6643327f85108282#2c072cc830d04af5f10b390e6643327f85108282"
+version = "0.10.1-dev"
+source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -124,8 +124,8 @@ dependencies = [
 
 [[package]]
 name = "chalk-engine"
-version = "0.9.0"
-source = "git+https://github.com/rust-lang/chalk.git?rev=2c072cc830d04af5f10b390e6643327f85108282#2c072cc830d04af5f10b390e6643327f85108282"
+version = "0.10.1-dev"
+source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
 dependencies = [
  "chalk-macros",
  "rustc-hash",
@@ -133,8 +133,8 @@ dependencies = [
 
 [[package]]
 name = "chalk-ir"
-version = "0.1.0"
-source = "git+https://github.com/rust-lang/chalk.git?rev=2c072cc830d04af5f10b390e6643327f85108282#2c072cc830d04af5f10b390e6643327f85108282"
+version = "0.10.1-dev"
+source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
 dependencies = [
  "chalk-derive",
  "chalk-engine",
@@ -143,16 +143,16 @@ dependencies = [
 
 [[package]]
 name = "chalk-macros"
-version = "0.1.1"
-source = "git+https://github.com/rust-lang/chalk.git?rev=2c072cc830d04af5f10b390e6643327f85108282#2c072cc830d04af5f10b390e6643327f85108282"
+version = "0.10.1-dev"
+source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
 dependencies = [
  "lazy_static",
 ]
 
 [[package]]
 name = "chalk-rust-ir"
-version = "0.1.0"
-source = "git+https://github.com/rust-lang/chalk.git?rev=2c072cc830d04af5f10b390e6643327f85108282#2c072cc830d04af5f10b390e6643327f85108282"
+version = "0.10.1-dev"
+source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
 dependencies = [
  "chalk-derive",
  "chalk-engine",
@@ -162,8 +162,8 @@ dependencies = [
 
 [[package]]
 name = "chalk-solve"
-version = "0.1.0"
-source = "git+https://github.com/rust-lang/chalk.git?rev=2c072cc830d04af5f10b390e6643327f85108282#2c072cc830d04af5f10b390e6643327f85108282"
+version = "0.10.1-dev"
+source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
 dependencies = [
  "chalk-derive",
  "chalk-engine",
@@ -342,9 +342,9 @@ dependencies = [
 
 [[package]]
 name = "filetime"
-version = "0.2.9"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f59efc38004c988e4201d11d263b8171f49a2e7ec0bdbb71773433f271504a5e"
+checksum = "affc17579b132fc2461adf7c575cc6e8b134ebca52c51f5411388965227dc695"
 dependencies = [
  "cfg-if",
  "libc",
@@ -360,9 +360,9 @@ checksum = "86d4de0081402f5e88cdac65c8dcdcc73118c1a7a465e2a05f0da05843a8ea33"
 
 [[package]]
 name = "fnv"
-version = "1.0.6"
+version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
 [[package]]
 name = "fs_extra"
@@ -423,6 +423,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "gimli"
+version = "0.21.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bcc8e0c9bce37868955864dbecd2b1ab2bdf967e6f28066d65aaac620444b65c"
+
+[[package]]
 name = "globset"
 version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -437,9 +443,9 @@ dependencies = [
 
 [[package]]
 name = "goblin"
-version = "0.2.1"
+version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ddd5e3132801a1ac34ac53b97acde50c4685414dd2f291b9ea52afa6f07468c8"
+checksum = "d20fd25aa456527ce4f544271ae4fea65d2eda4a6561ea56f39fb3ee4f7e3884"
 dependencies = [
  "log",
  "plain",
@@ -457,14 +463,23 @@ dependencies = [
 
 [[package]]
 name = "hermit-abi"
-version = "0.1.12"
+version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "61565ff7aaace3525556587bd2dc31d4a07071957be715e63ce7b1eccf51a8f4"
+checksum = "91780f809e750b0a89f5544be56617ff6b1227ee485bcb06ebe10cdf89bd3b71"
 dependencies = [
  "libc",
 ]
 
 [[package]]
+name = "home"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2456aef2e6b6a9784192ae780c0f15bc57df0e918585282325e8c8ac27737654"
+dependencies = [
+ "winapi 0.3.8",
+]
+
+[[package]]
 name = "idna"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -604,24 +619,24 @@ checksum = "b294d6fa9ee409a054354afc4352b0b9ef7ca222c69b8812cbea9e7d2bf3783f"
 
 [[package]]
 name = "libc"
-version = "0.2.69"
+version = "0.2.70"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "99e85c08494b21a9054e7fe1374a732aeadaff3980b6990b94bfd3a70f690005"
+checksum = "3baa92041a6fec78c687fa0cc2b3fae8884f743d672cf551bed1d6dac6988d0f"
 
 [[package]]
 name = "libloading"
-version = "0.6.1"
+version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c4f51b790f5bdb65acb4cc94bb81d7b2ee60348a5431ac1467d390b017600b0"
+checksum = "2cadb8e769f070c45df05c78c7520eb4cd17061d4ab262e43cfc68b4d00ac71c"
 dependencies = [
  "winapi 0.3.8",
 ]
 
 [[package]]
 name = "linked-hash-map"
-version = "0.5.2"
+version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ae91b68aebc4ddb91978b11a1b02ddd8602a05ec19002801c5666000e05e0f83"
+checksum = "8dd5a6d5999d9907cda8ed67bbd137d3af8085216c2ac62de5be860bd41f304a"
 
 [[package]]
 name = "lock_api"
@@ -655,9 +670,9 @@ dependencies = [
 
 [[package]]
 name = "lsp-types"
-version = "0.74.0"
+version = "0.74.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "820f746e5716ab9a2d664794636188bd003023b72e55404ee27105dc22869922"
+checksum = "57c0e6a2b8837d27b29deb3f3e6dc1c6d2f57947677f9be1024e482ec5b59525"
 dependencies = [
  "base64",
  "bitflags",
@@ -706,9 +721,9 @@ dependencies = [
 
 [[package]]
 name = "mio"
-version = "0.6.21"
+version = "0.6.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "302dec22bcf6bae6dfb69c647187f4b4d0fb6f535521f7bc022430ce8e12008f"
+checksum = "fce347092656428bc8eaf6201042cb551b8d67855af7374542a92a0fbfcac430"
 dependencies = [
  "cfg-if",
  "fuchsia-zircon",
@@ -749,9 +764,9 @@ dependencies = [
 
 [[package]]
 name = "net2"
-version = "0.2.33"
+version = "0.2.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "42550d9fb7b6684a6d404d9fa7250c2eb2646df731d1c06afc06dcee9e1bcf88"
+checksum = "2ba7c918ac76704fb42afcbbb43891e72731f3dcca3bef2a19786297baf14af7"
 dependencies = [
  "cfg-if",
  "libc",
@@ -787,10 +802,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "object"
+version = "0.19.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9cbca9424c482ee628fa549d9c812e2cd22f1180b9222c9200fdfa6eb31aecb2"
+
+[[package]]
 name = "once_cell"
-version = "1.3.1"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b1c601810575c99596d4afc46f78a678c80105117c379eb3650cf99b8a21ce5b"
+checksum = "0b631f7e854af39a1739f401cf34a8a013dfe09eac4fa4dba91e9768bd28168d"
 
 [[package]]
 name = "ordermap"
@@ -824,9 +845,9 @@ dependencies = [
 
 [[package]]
 name = "paste"
-version = "0.1.11"
+version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a3c897744f63f34f7ae3a024d9162bb5001f4ad661dd24bea0dc9f075d2de1c6"
+checksum = "0a229b1c58c692edcaa5b9b0948084f130f55d2dcc15b02fcc5340b2b4521476"
 dependencies = [
  "paste-impl",
  "proc-macro-hack",
@@ -834,9 +855,9 @@ dependencies = [
 
 [[package]]
 name = "paste-impl"
-version = "0.1.11"
+version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "66fd6f92e3594f2dd7b3fc23e42d82e292f7bcda6d8e5dcd167072327234ab89"
+checksum = "2e0bf239e447e67ff6d16a8bb5e4d4bd2343acf5066061c0e8e06ac5ba8ca68c"
 dependencies = [
  "proc-macro-hack",
  "proc-macro2",
@@ -874,9 +895,9 @@ checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"
 
 [[package]]
 name = "ppv-lite86"
-version = "0.2.6"
+version = "0.2.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74490b50b9fbe561ac330df47c08f3f33073d2d00c150f719147d7c54522fa1b"
+checksum = "237a5ed80e274dbc66f86bd59c1e25edc039660be53194b5fe0a482e0f2612ea"
 
 [[package]]
 name = "proc-macro-hack"
@@ -886,18 +907,18 @@ checksum = "0d659fe7c6d27f25e9d80a1a094c223f5246f6a6596453e09d7229bf42750b63"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.10"
+version = "1.0.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "df246d292ff63439fea9bc8c0a270bed0e390d5ebd4db4ba15aba81111b5abe3"
+checksum = "53f5ffe53a6b28e37c9c1ce74893477864d64f74778a93a4beb43c8fa167f639"
 dependencies = [
  "unicode-xid",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.4"
+version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4c1f4b0efa5fc5e8ceb705136bfee52cfdb6a4e3509f770b478cd6ed434232a7"
+checksum = "54a21852a652ad6f610c9510194f398ff6f8692e334fd1145fed931f7fbe44ea"
 dependencies = [
  "proc-macro2",
 ]
@@ -954,10 +975,9 @@ version = "0.1.0"
 dependencies = [
  "cargo_metadata",
  "crossbeam-channel",
- "insta",
  "jod-thread",
  "log",
- "lsp-types",
+ "ra_toolchain",
  "serde_json",
 ]
 
@@ -1163,6 +1183,7 @@ dependencies = [
  "ra_cfg",
  "ra_db",
  "ra_proc_macro",
+ "ra_toolchain",
  "rustc-hash",
  "serde",
  "serde_json",
@@ -1195,6 +1216,13 @@ dependencies = [
 ]
 
 [[package]]
+name = "ra_toolchain"
+version = "0.1.0"
+dependencies = [
+ "home",
+]
+
+[[package]]
 name = "ra_tt"
 version = "0.1.0"
 dependencies = [
@@ -1203,9 +1231,9 @@ dependencies = [
 
 [[package]]
 name = "ra_vfs"
-version = "0.6.0"
+version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fcaa5615f420134aea7667253db101d03a5c5f300eac607872dc2a36407b2ac9"
+checksum = "cbf31a173fc77ec59c27cf39af6baa137b40f4dbd45a8b3eccb1b2e4cfc922c1"
 dependencies = [
  "crossbeam-channel",
  "jod-thread",
@@ -1351,6 +1379,7 @@ dependencies = [
  "crossbeam-channel",
  "env_logger",
  "globset",
+ "insta",
  "itertools",
  "jod-thread",
  "log",
@@ -1469,9 +1498,9 @@ dependencies = [
 
 [[package]]
 name = "scroll_derive"
-version = "0.10.1"
+version = "0.10.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f8584eea9b9ff42825b46faf46a8c24d2cff13ec152fa2a50df788b87c07ee28"
+checksum = "e367622f934864ffa1c704ba2b82280aab856e3d8213c84c5720257eb34b15b9"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1496,18 +1525,18 @@ checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 
 [[package]]
 name = "serde"
-version = "1.0.106"
+version = "1.0.110"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "36df6ac6412072f67cf767ebbde4133a5b2e88e76dc6187fa7104cd16f783399"
+checksum = "99e7b308464d16b56eba9964e4972a3eee817760ab60d88c3f86e1fecb08204c"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.106"
+version = "1.0.110"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e549e3abf4fb8621bd1609f11dfc9f5e50320802273b12f3811a67e6716ea6c"
+checksum = "818fbf6bfa9a42d3bfcaca148547aa00c7b915bec71d1757aa2d44ca68771984"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1516,9 +1545,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.52"
+version = "1.0.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a7894c8ed05b7a3a279aeb79025fdec1d3158080b75b98a08faf2806bb799edd"
+checksum = "993948e75b189211a9b31a7528f950c6adc21f9720b6438ff80a7fa2f864cea2"
 dependencies = [
  "itoa",
  "ryu",
@@ -1538,9 +1567,9 @@ dependencies = [
 
 [[package]]
 name = "serde_yaml"
-version = "0.8.11"
+version = "0.8.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "691b17f19fc1ec9d94ec0b5864859290dff279dbd7b03f017afda54eb36c3c35"
+checksum = "16c7a592a1ec97c9c1c68d75b6e537dcbf60c7618e038e7841e00af1d9ccf0c4"
 dependencies = [
  "dtoa",
  "linked-hash-map",
@@ -1581,9 +1610,9 @@ checksum = "ab16ced94dbd8a46c82fd81e3ed9a8727dac2977ea869d217bcc4ea1f122e81f"
 
 [[package]]
 name = "syn"
-version = "1.0.18"
+version = "1.0.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "410a7488c0a728c7ceb4ad59b9567eb4053d02e8cc7f5c0e0eeeb39518369213"
+checksum = "1425de3c33b0941002740a420b1a906a350b88d08b82b2c8a01035a3f9447bac"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1667,9 +1696,9 @@ dependencies = [
 
 [[package]]
 name = "threadpool"
-version = "1.8.0"
+version = "1.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e8dae184447c15d5a6916d973c642aec485105a13cd238192a6927ae3e077d66"
+checksum = "d050e60b33d41c19108b32cea32164033a9013fe3b46cbd4457559bfbf77afaa"
 dependencies = [
  "num_cpus",
 ]
diff --git a/crates/ra_assists/src/assist_config.rs b/crates/ra_assists/src/assist_config.rs
new file mode 100644
index 000000000..c0a0226fb
--- /dev/null
+++ b/crates/ra_assists/src/assist_config.rs
@@ -0,0 +1,27 @@
+//! Settings for tweaking assists.
+//!
+//! The fun thing here is `SnippetCap` -- this type can only be created in this
+//! module, and we use to statically check that we only produce snippet
+//! assists if we are allowed to.
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct AssistConfig {
+    pub snippet_cap: Option<SnippetCap>,
+}
+
+impl AssistConfig {
+    pub fn allow_snippets(&mut self, yes: bool) {
+        self.snippet_cap = if yes { Some(SnippetCap { _private: () }) } else { None }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct SnippetCap {
+    _private: (),
+}
+
+impl Default for AssistConfig {
+    fn default() -> Self {
+        AssistConfig { snippet_cap: Some(SnippetCap { _private: () }) }
+    }
+}
diff --git a/crates/ra_assists/src/assist_context.rs b/crates/ra_assists/src/assist_context.rs
new file mode 100644
index 000000000..f3af70a3e
--- /dev/null
+++ b/crates/ra_assists/src/assist_context.rs
@@ -0,0 +1,257 @@
+//! See `AssistContext`
+
+use algo::find_covering_element;
+use hir::Semantics;
+use ra_db::{FileId, FileRange};
+use ra_fmt::{leading_indent, reindent};
+use ra_ide_db::{
+    source_change::{SingleFileChange, SourceChange},
+    RootDatabase,
+};
+use ra_syntax::{
+    algo::{self, find_node_at_offset, SyntaxRewriter},
+    AstNode, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange, TextSize,
+    TokenAtOffset,
+};
+use ra_text_edit::TextEditBuilder;
+
+use crate::{
+    assist_config::{AssistConfig, SnippetCap},
+    Assist, AssistId, GroupLabel, ResolvedAssist,
+};
+
+/// `AssistContext` allows to apply an assist or check if it could be applied.
+///
+/// Assists use a somewhat over-engineered approach, given the current needs.
+/// The assists workflow consists of two phases. In the first phase, a user asks
+/// for the list of available assists. In the second phase, the user picks a
+/// particular assist and it gets applied.
+///
+/// There are two peculiarities here:
+///
+/// * first, we ideally avoid computing more things then necessary to answer "is
+///   assist applicable" in the first phase.
+/// * second, when we are applying assist, we don't have a guarantee that there
+///   weren't any changes between the point when user asked for assists and when
+///   they applied a particular assist. So, when applying assist, we need to do
+///   all the checks from scratch.
+///
+/// To avoid repeating the same code twice for both "check" and "apply"
+/// functions, we use an approach reminiscent of that of Django's function based
+/// views dealing with forms. Each assist receives a runtime parameter,
+/// `resolve`. It first check if an edit is applicable (potentially computing
+/// info required to compute the actual edit). If it is applicable, and
+/// `resolve` is `true`, it then computes the actual edit.
+///
+/// So, to implement the original assists workflow, we can first apply each edit
+/// with `resolve = false`, and then applying the selected edit again, with
+/// `resolve = true` this time.
+///
+/// Note, however, that we don't actually use such two-phase logic at the
+/// moment, because the LSP API is pretty awkward in this place, and it's much
+/// easier to just compute the edit eagerly :-)
+pub(crate) struct AssistContext<'a> {
+    pub(crate) config: &'a AssistConfig,
+    pub(crate) sema: Semantics<'a, RootDatabase>,
+    pub(crate) db: &'a RootDatabase,
+    pub(crate) frange: FileRange,
+    source_file: SourceFile,
+}
+
+impl<'a> AssistContext<'a> {
+    pub(crate) fn new(
+        sema: Semantics<'a, RootDatabase>,
+        config: &'a AssistConfig,
+        frange: FileRange,
+    ) -> AssistContext<'a> {
+        let source_file = sema.parse(frange.file_id);
+        let db = sema.db;
+        AssistContext { config, sema, db, frange, source_file }
+    }
+
+    // NB, this ignores active selection.
+    pub(crate) fn offset(&self) -> TextSize {
+        self.frange.range.start()
+    }
+
+    pub(crate) fn token_at_offset(&self) -> TokenAtOffset<SyntaxToken> {
+        self.source_file.syntax().token_at_offset(self.offset())
+    }
+    pub(crate) fn find_token_at_offset(&self, kind: SyntaxKind) -> Option<SyntaxToken> {
+        self.token_at_offset().find(|it| it.kind() == kind)
+    }
+    pub(crate) fn find_node_at_offset<N: AstNode>(&self) -> Option<N> {
+        find_node_at_offset(self.source_file.syntax(), self.offset())
+    }
+    pub(crate) fn find_node_at_offset_with_descend<N: AstNode>(&self) -> Option<N> {
+        self.sema.find_node_at_offset_with_descend(self.source_file.syntax(), self.offset())
+    }
+    pub(crate) fn covering_element(&self) -> SyntaxElement {
+        find_covering_element(self.source_file.syntax(), self.frange.range)
+    }
+    // FIXME: remove
+    pub(crate) fn covering_node_for_range(&self, range: TextRange) -> SyntaxElement {
+        find_covering_element(self.source_file.syntax(), range)
+    }
+}
+
+pub(crate) struct Assists {
+    resolve: bool,
+    file: FileId,
+    buf: Vec<(Assist, Option<SourceChange>)>,
+}
+
+impl Assists {
+    pub(crate) fn new_resolved(ctx: &AssistContext) -> Assists {
+        Assists { resolve: true, file: ctx.frange.file_id, buf: Vec::new() }
+    }
+    pub(crate) fn new_unresolved(ctx: &AssistContext) -> Assists {
+        Assists { resolve: false, file: ctx.frange.file_id, buf: Vec::new() }
+    }
+
+    pub(crate) fn finish_unresolved(self) -> Vec<Assist> {
+        assert!(!self.resolve);
+        self.finish()
+            .into_iter()
+            .map(|(label, edit)| {
+                assert!(edit.is_none());
+                label
+            })
+            .collect()
+    }
+
+    pub(crate) fn finish_resolved(self) -> Vec<ResolvedAssist> {
+        assert!(self.resolve);
+        self.finish()
+            .into_iter()
+            .map(|(label, edit)| ResolvedAssist { assist: label, source_change: edit.unwrap() })
+            .collect()
+    }
+
+    pub(crate) fn add(
+        &mut self,
+        id: AssistId,
+        label: impl Into<String>,
+        target: TextRange,
+        f: impl FnOnce(&mut AssistBuilder),
+    ) -> Option<()> {
+        let label = Assist::new(id, label.into(), None, target);
+        self.add_impl(label, f)
+    }
+    pub(crate) fn add_group(
+        &mut self,
+        group: &GroupLabel,
+        id: AssistId,
+        label: impl Into<String>,
+        target: TextRange,
+        f: impl FnOnce(&mut AssistBuilder),
+    ) -> Option<()> {
+        let label = Assist::new(id, label.into(), Some(group.clone()), target);
+        self.add_impl(label, f)
+    }
+    fn add_impl(&mut self, label: Assist, f: impl FnOnce(&mut AssistBuilder)) -> Option<()> {
+        let change_label = label.label.clone();
+        let source_change = if self.resolve {
+            let mut builder = AssistBuilder::new(self.file);
+            f(&mut builder);
+            Some(builder.finish(change_label))
+        } else {
+            None
+        };
+
+        self.buf.push((label, source_change));
+        Some(())
+    }
+
+    fn finish(mut self) -> Vec<(Assist, Option<SourceChange>)> {
+        self.buf.sort_by_key(|(label, _edit)| label.target.len());
+        self.buf
+    }
+}
+
+pub(crate) struct AssistBuilder {
+    edit: TextEditBuilder,
+    file: FileId,
+    is_snippet: bool,
+}
+
+impl AssistBuilder {
+    pub(crate) fn new(file: FileId) -> AssistBuilder {
+        AssistBuilder { edit: TextEditBuilder::default(), file, is_snippet: false }
+    }
+
+    /// Remove specified `range` of text.
+    pub(crate) fn delete(&mut self, range: TextRange) {
+        self.edit.delete(range)
+    }
+    /// Append specified `text` at the given `offset`
+    pub(crate) fn insert(&mut self, offset: TextSize, text: impl Into<String>) {
+        self.edit.insert(offset, text.into())
+    }
+    /// Append specified `snippet` at the given `offset`
+    pub(crate) fn insert_snippet(
+        &mut self,
+        _cap: SnippetCap,
+        offset: TextSize,
+        snippet: impl Into<String>,
+    ) {
+        self.is_snippet = true;
+        self.insert(offset, snippet);
+    }
+    /// Replaces specified `range` of text with a given string.
+    pub(crate) fn replace(&mut self, range: TextRange, replace_with: impl Into<String>) {
+        self.edit.replace(range, replace_with.into())
+    }
+    /// Replaces specified `range` of text with a given `snippet`.
+    pub(crate) fn replace_snippet(
+        &mut self,
+        _cap: SnippetCap,
+        range: TextRange,
+        snippet: impl Into<String>,
+    ) {
+        self.is_snippet = true;
+        self.replace(range, snippet);
+    }
+    pub(crate) fn replace_ast<N: AstNode>(&mut self, old: N, new: N) {
+        algo::diff(old.syntax(), new.syntax()).into_text_edit(&mut self.edit)
+    }
+    /// Replaces specified `node` of text with a given string, reindenting the
+    /// string to maintain `node`'s existing indent.
+    // FIXME: remove in favor of ra_syntax::edit::IndentLevel::increase_indent
+    pub(crate) fn replace_node_and_indent(
+        &mut self,
+        node: &SyntaxNode,
+        replace_with: impl Into<String>,
+    ) {
+        let mut replace_with = replace_with.into();
+        if let Some(indent) = leading_indent(node) {
+            replace_with = reindent(&replace_with, &indent)
+        }
+        self.replace(node.text_range(), replace_with)
+    }
+    pub(crate) fn rewrite(&mut self, rewriter: SyntaxRewriter) {
+        let node = rewriter.rewrite_root().unwrap();
+        let new = rewriter.rewrite(&node);
+        algo::diff(&node, &new).into_text_edit(&mut self.edit)
+    }
+
+    // FIXME: better API
+    pub(crate) fn set_file(&mut self, assist_file: FileId) {
+        self.file = assist_file;
+    }
+
+    // FIXME: kill this API
+    /// Get access to the raw `TextEditBuilder`.
+    pub(crate) fn text_edit_builder(&mut self) -> &mut TextEditBuilder {
+        &mut self.edit
+    }
+
+    fn finish(self, change_label: String) -> SourceChange {
+        let edit = self.edit.finish();
+        let mut res = SingleFileChange { label: change_label, edit }.into_source_change(self.file);
+        if self.is_snippet {
+            res.is_snippet = true;
+        }
+        res
+    }
+}
diff --git a/crates/ra_assists/src/assist_ctx.rs b/crates/ra_assists/src/assist_ctx.rs
deleted file mode 100644
index 2fe7c3de3..000000000
--- a/crates/ra_assists/src/assist_ctx.rs
+++ /dev/null
@@ -1,257 +0,0 @@
-//! This module defines `AssistCtx` -- the API surface that is exposed to assists.
-use hir::Semantics;
-use ra_db::FileRange;
-use ra_fmt::{leading_indent, reindent};
-use ra_ide_db::RootDatabase;
-use ra_syntax::{
-    algo::{self, find_covering_element, find_node_at_offset},
-    AstNode, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange, TextSize,
-    TokenAtOffset,
-};
-use ra_text_edit::TextEditBuilder;
-
-use crate::{AssistAction, AssistFile, AssistId, AssistLabel, GroupLabel, ResolvedAssist};
-use algo::SyntaxRewriter;
-
-#[derive(Clone, Debug)]
-pub(crate) struct Assist(pub(crate) Vec<AssistInfo>);
-
-#[derive(Clone, Debug)]
-pub(crate) struct AssistInfo {
-    pub(crate) label: AssistLabel,
-    pub(crate) group_label: Option<GroupLabel>,
-    pub(crate) action: Option<AssistAction>,
-}
-
-impl AssistInfo {
-    fn new(label: AssistLabel) -> AssistInfo {
-        AssistInfo { label, group_label: None, action: None }
-    }
-
-    fn resolved(self, action: AssistAction) -> AssistInfo {
-        AssistInfo { action: Some(action), ..self }
-    }
-
-    fn with_group(self, group_label: GroupLabel) -> AssistInfo {
-        AssistInfo { group_label: Some(group_label), ..self }
-    }
-
-    pub(crate) fn into_resolved(self) -> Option<ResolvedAssist> {
-        let label = self.label;
-        let group_label = self.group_label;
-        self.action.map(|action| ResolvedAssist { label, group_label, action })
-    }
-}
-
-pub(crate) type AssistHandler = fn(AssistCtx) -> Option<Assist>;
-
-/// `AssistCtx` allows to apply an assist or check if it could be applied.
-///
-/// Assists use a somewhat over-engineered approach, given the current needs. The
-/// assists workflow consists of two phases. In the first phase, a user asks for
-/// the list of available assists. In the second phase, the user picks a
-/// particular assist and it gets applied.
-///
-/// There are two peculiarities here:
-///
-/// * first, we ideally avoid computing more things then necessary to answer
-///   "is assist applicable" in the first phase.
-/// * second, when we are applying assist, we don't have a guarantee that there
-///   weren't any changes between the point when user asked for assists and when
-///   they applied a particular assist. So, when applying assist, we need to do
-///   all the checks from scratch.
-///
-/// To avoid repeating the same code twice for both "check" and "apply"
-/// functions, we use an approach reminiscent of that of Django's function based
-/// views dealing with forms. Each assist receives a runtime parameter,
-/// `should_compute_edit`. It first check if an edit is applicable (potentially
-/// computing info required to compute the actual edit). If it is applicable,
-/// and `should_compute_edit` is `true`, it then computes the actual edit.
-///
-/// So, to implement the original assists workflow, we can first apply each edit
-/// with `should_compute_edit = false`, and then applying the selected edit
-/// again, with `should_compute_edit = true` this time.
-///
-/// Note, however, that we don't actually use such two-phase logic at the
-/// moment, because the LSP API is pretty awkward in this place, and it's much
-/// easier to just compute the edit eagerly :-)
-#[derive(Clone)]
-pub(crate) struct AssistCtx<'a> {
-    pub(crate) sema: &'a Semantics<'a, RootDatabase>,
-    pub(crate) db: &'a RootDatabase,
-    pub(crate) frange: FileRange,
-    source_file: SourceFile,
-    should_compute_edit: bool,
-}
-
-impl<'a> AssistCtx<'a> {
-    pub fn new(
-        sema: &'a Semantics<'a, RootDatabase>,
-        frange: FileRange,
-        should_compute_edit: bool,
-    ) -> AssistCtx<'a> {
-        let source_file = sema.parse(frange.file_id);
-        AssistCtx { sema, db: sema.db, frange, source_file, should_compute_edit }
-    }
-
-    pub(crate) fn add_assist(
-        self,
-        id: AssistId,
-        label: impl Into<String>,
-        f: impl FnOnce(&mut ActionBuilder),
-    ) -> Option<Assist> {
-        let label = AssistLabel::new(label.into(), id);
-
-        let mut info = AssistInfo::new(label);
-        if self.should_compute_edit {
-            let action = {
-                let mut edit = ActionBuilder::default();
-                f(&mut edit);
-                edit.build()
-            };
-            info = info.resolved(action)
-        };
-
-        Some(Assist(vec![info]))
-    }
-
-    pub(crate) fn add_assist_group(self, group_name: impl Into<String>) -> AssistGroup<'a> {
-        AssistGroup { ctx: self, group_name: group_name.into(), assists: Vec::new() }
-    }
-
-    pub(crate) fn token_at_offset(&self) -> TokenAtOffset<SyntaxToken> {
-        self.source_file.syntax().token_at_offset(self.frange.range.start())
-    }
-
-    pub(crate) fn find_token_at_offset(&self, kind: SyntaxKind) -> Option<SyntaxToken> {
-        self.token_at_offset().find(|it| it.kind() == kind)
-    }
-
-    pub(crate) fn find_node_at_offset<N: AstNode>(&self) -> Option<N> {
-        find_node_at_offset(self.source_file.syntax(), self.frange.range.start())
-    }
-    pub(crate) fn covering_element(&self) -> SyntaxElement {
-        find_covering_element(self.source_file.syntax(), self.frange.range)
-    }
-    pub(crate) fn covering_node_for_range(&self, range: TextRange) -> SyntaxElement {
-        find_covering_element(self.source_file.syntax(), range)
-    }
-}
-
-pub(crate) struct AssistGroup<'a> {
-    ctx: AssistCtx<'a>,
-    group_name: String,
-    assists: Vec<AssistInfo>,
-}
-
-impl<'a> AssistGroup<'a> {
-    pub(crate) fn add_assist(
-        &mut self,
-        id: AssistId,
-        label: impl Into<String>,
-        f: impl FnOnce(&mut ActionBuilder),
-    ) {
-        let label = AssistLabel::new(label.into(), id);
-
-        let mut info = AssistInfo::new(label).with_group(GroupLabel(self.group_name.clone()));
-        if self.ctx.should_compute_edit {
-            let action = {
-                let mut edit = ActionBuilder::default();
-                f(&mut edit);
-                edit.build()
-            };
-            info = info.resolved(action)
-        };
-
-        self.assists.push(info)
-    }
-
-    pub(crate) fn finish(self) -> Option<Assist> {
-        if self.assists.is_empty() {
-            None
-        } else {
-            Some(Assist(self.assists))
-        }
-    }
-}
-
-#[derive(Default)]
-pub(crate) struct ActionBuilder {
-    edit: TextEditBuilder,
-    cursor_position: Option<TextSize>,
-    target: Option<TextRange>,
-    file: AssistFile,
-}
-
-impl ActionBuilder {
-    /// Replaces specified `range` of text with a given string.
-    pub(crate) fn replace(&mut self, range: TextRange, replace_with: impl Into<String>) {
-        self.edit.replace(range, replace_with.into())
-    }
-
-    /// Replaces specified `node` of text with a given string, reindenting the
-    /// string to maintain `node`'s existing indent.
-    // FIXME: remove in favor of ra_syntax::edit::IndentLevel::increase_indent
-    pub(crate) fn replace_node_and_indent(
-        &mut self,
-        node: &SyntaxNode,
-        replace_with: impl Into<String>,
-    ) {
-        let mut replace_with = replace_with.into();
-        if let Some(indent) = leading_indent(node) {
-            replace_with = reindent(&replace_with, &indent)
-        }
-        self.replace(node.text_range(), replace_with)
-    }
-
-    /// Remove specified `range` of text.
-    #[allow(unused)]
-    pub(crate) fn delete(&mut self, range: TextRange) {
-        self.edit.delete(range)
-    }
-
-    /// Append specified `text` at the given `offset`
-    pub(crate) fn insert(&mut self, offset: TextSize, text: impl Into<String>) {
-        self.edit.insert(offset, text.into())
-    }
-
-    /// Specify desired position of the cursor after the assist is applied.
-    pub(crate) fn set_cursor(&mut self, offset: TextSize) {
-        self.cursor_position = Some(offset)
-    }
-
-    /// Specify that the assist should be active withing the `target` range.
-    ///
-    /// Target ranges are used to sort assists: the smaller the target range,
-    /// the more specific assist is, and so it should be sorted first.
-    pub(crate) fn target(&mut self, target: TextRange) {
-        self.target = Some(target)
-    }
-
-    /// Get access to the raw `TextEditBuilder`.
-    pub(crate) fn text_edit_builder(&mut self) -> &mut TextEditBuilder {
-        &mut self.edit
-    }
-
-    pub(crate) fn replace_ast<N: AstNode>(&mut self, old: N, new: N) {
-        algo::diff(old.syntax(), new.syntax()).into_text_edit(&mut self.edit)
-    }
-    pub(crate) fn rewrite(&mut self, rewriter: SyntaxRewriter) {
-        let node = rewriter.rewrite_root().unwrap();
-        let new = rewriter.rewrite(&node);
-        algo::diff(&node, &new).into_text_edit(&mut self.edit)
-    }
-
-    pub(crate) fn set_file(&mut self, assist_file: AssistFile) {
-        self.file = assist_file
-    }
-
-    fn build(self) -> AssistAction {
-        AssistAction {
-            edit: self.edit.finish(),
-            cursor_position: self.cursor_position,
-            target: self.target,
-            file: self.file,
-        }
-    }
-}
diff --git a/crates/ra_assists/src/ast_transform.rs b/crates/ra_assists/src/ast_transform.rs
index 9ac65ab39..3079a02a2 100644
--- a/crates/ra_assists/src/ast_transform.rs
+++ b/crates/ra_assists/src/ast_transform.rs
@@ -1,7 +1,7 @@
 //! `AstTransformer`s are functions that replace nodes in an AST and can be easily combined.
 use rustc_hash::FxHashMap;
 
-use hir::{PathResolution, SemanticsScope};
+use hir::{HirDisplay, PathResolution, SemanticsScope};
 use ra_ide_db::RootDatabase;
 use ra_syntax::{
     algo::SyntaxRewriter,
@@ -51,7 +51,27 @@ impl<'a> SubstituteTypeParams<'a> {
             .into_iter()
             // this is a trait impl, so we need to skip the first type parameter -- this is a bit hacky
             .skip(1)
-            .zip(substs.into_iter())
+            // The actual list of trait type parameters may be longer than the one
+            // used in the `impl` block due to trailing default type parametrs.
+            // For that case we extend the `substs` with an empty iterator so we
+            // can still hit those trailing values and check if they actually have
+            // a default type. If they do, go for that type from `hir` to `ast` so
+            // the resulting change can be applied correctly.
+            .zip(substs.into_iter().map(Some).chain(std::iter::repeat(None)))
+            .filter_map(|(k, v)| match v {
+                Some(v) => Some((k, v)),
+                None => {
+                    let default = k.default(source_scope.db)?;
+                    Some((
+                        k,
+                        ast::make::type_ref(
+                            &default
+                                .display_source_code(source_scope.db, source_scope.module()?.into())
+                                .ok()?,
+                        ),
+                    ))
+                }
+            })
             .collect();
         return SubstituteTypeParams {
             source_scope,
diff --git a/crates/ra_assists/src/doc_tests.rs b/crates/ra_assists/src/doc_tests.rs
deleted file mode 100644
index c0f9bc1fb..000000000
--- a/crates/ra_assists/src/doc_tests.rs
+++ /dev/null
@@ -1,35 +0,0 @@
-//! Each assist definition has a special comment, which specifies docs and
-//! example.
-//!
-//! We collect all the example and write the as tests in this module.
-
-mod generated;
-
-use ra_db::FileRange;
-use test_utils::{assert_eq_text, extract_range_or_offset};
-
-use crate::resolved_assists;
-
-fn check(assist_id: &str, before: &str, after: &str) {
-    let (selection, before) = extract_range_or_offset(before);
-    let (db, file_id) = crate::helpers::with_single_file(&before);
-    let frange = FileRange { file_id, range: selection.into() };
-
-    let assist = resolved_assists(&db, frange)
-        .into_iter()
-        .find(|assist| assist.label.id.0 == assist_id)
-        .unwrap_or_else(|| {
-            panic!(
-                "\n\nAssist is not applicable: {}\nAvailable assists: {}",
-                assist_id,
-                resolved_assists(&db, frange)
-                    .into_iter()
-                    .map(|assist| assist.label.id.0)
-                    .collect::<Vec<_>>()
-                    .join(", ")
-            )
-        });
-
-    let actual = assist.action.edit.apply(&before);
-    assert_eq_text!(after, &actual);
-}
diff --git a/crates/ra_assists/src/handlers/add_custom_impl.rs b/crates/ra_assists/src/handlers/add_custom_impl.rs
index 4ea26a550..fa70c8496 100644
--- a/crates/ra_assists/src/handlers/add_custom_impl.rs
+++ b/crates/ra_assists/src/handlers/add_custom_impl.rs
@@ -6,7 +6,10 @@ use ra_syntax::{
 };
 use stdx::SepBy;
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{
+    assist_context::{AssistContext, Assists},
+    AssistId,
+};
 
 // Assist: add_custom_impl
 //
@@ -22,10 +25,10 @@ use crate::{Assist, AssistCtx, AssistId};
 // struct S;
 //
 // impl Debug for S {
-//
+//     $0
 // }
 // ```
-pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_custom_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let input = ctx.find_node_at_offset::<ast::AttrInput>()?;
     let attr = input.syntax().parent().and_then(ast::Attr::cast)?;
 
@@ -46,11 +49,10 @@ pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
     let start_offset = annotated.syntax().parent()?.text_range().end();
 
     let label =
-        format!("Add custom impl '{}' for '{}'", trait_token.text().as_str(), annotated_name);
-
-    ctx.add_assist(AssistId("add_custom_impl"), label, |edit| {
-        edit.target(attr.syntax().text_range());
+        format!("Add custom impl `{}` for `{}`", trait_token.text().as_str(), annotated_name);
 
+    let target = attr.syntax().text_range();
+    acc.add(AssistId("add_custom_impl"), label, target, |builder| {
         let new_attr_input = input
             .syntax()
             .descendants_with_tokens()
@@ -61,20 +63,11 @@ pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
         let has_more_derives = !new_attr_input.is_empty();
         let new_attr_input = new_attr_input.iter().sep_by(", ").surround_with("(", ")").to_string();
 
-        let mut buf = String::new();
-        buf.push_str("\n\nimpl ");
-        buf.push_str(trait_token.text().as_str());
-        buf.push_str(" for ");
-        buf.push_str(annotated_name.as_str());
-        buf.push_str(" {\n");
-
-        let cursor_delta = if has_more_derives {
-            let delta = input.syntax().text_range().len() - TextSize::of(&new_attr_input);
-            edit.replace(input.syntax().text_range(), new_attr_input);
-            delta
+        if has_more_derives {
+            builder.replace(input.syntax().text_range(), new_attr_input);
         } else {
             let attr_range = attr.syntax().text_range();
-            edit.delete(attr_range);
+            builder.delete(attr_range);
 
             let line_break_range = attr
                 .syntax()
@@ -82,20 +75,30 @@ pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
                 .filter(|t| t.kind() == WHITESPACE)
                 .map(|t| t.text_range())
                 .unwrap_or_else(|| TextRange::new(TextSize::from(0), TextSize::from(0)));
-            edit.delete(line_break_range);
-
-            attr_range.len() + line_break_range.len()
-        };
-
-        edit.set_cursor(start_offset + TextSize::of(&buf) - cursor_delta);
-        buf.push_str("\n}");
-        edit.insert(start_offset, buf);
+            builder.delete(line_break_range);
+        }
+
+        match ctx.config.snippet_cap {
+            Some(cap) => {
+                builder.insert_snippet(
+                    cap,
+                    start_offset,
+                    format!("\n\nimpl {} for {} {{\n    $0\n}}", trait_token, annotated_name),
+                );
+            }
+            None => {
+                builder.insert(
+                    start_offset,
+                    format!("\n\nimpl {} for {} {{\n\n}}", trait_token, annotated_name),
+                );
+            }
+        }
     })
 }
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
@@ -115,7 +118,7 @@ struct Foo {
 }
 
 impl Debug for Foo {
-<|>
+    $0
 }
             ",
         )
@@ -137,7 +140,7 @@ pub struct Foo {
 }
 
 impl Debug for Foo {
-<|>
+    $0
 }
             ",
         )
@@ -156,7 +159,7 @@ struct Foo {}
 struct Foo {}
 
 impl Debug for Foo {
-<|>
+    $0
 }
             ",
         )
diff --git a/crates/ra_assists/src/handlers/add_derive.rs b/crates/ra_assists/src/handlers/add_derive.rs
index 6254eb7c4..b123b8498 100644
--- a/crates/ra_assists/src/handlers/add_derive.rs
+++ b/crates/ra_assists/src/handlers/add_derive.rs
@@ -4,7 +4,7 @@ use ra_syntax::{
     TextSize,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: add_derive
 //
@@ -18,31 +18,37 @@ use crate::{Assist, AssistCtx, AssistId};
 // ```
 // ->
 // ```
-// #[derive()]
+// #[derive($0)]
 // struct Point {
 //     x: u32,
 //     y: u32,
 // }
 // ```
-pub(crate) fn add_derive(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_derive(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let cap = ctx.config.snippet_cap?;
     let nominal = ctx.find_node_at_offset::<ast::NominalDef>()?;
     let node_start = derive_insertion_offset(&nominal)?;
-    ctx.add_assist(AssistId("add_derive"), "Add `#[derive]`", |edit| {
+    let target = nominal.syntax().text_range();
+    acc.add(AssistId("add_derive"), "Add `#[derive]`", target, |builder| {
         let derive_attr = nominal
             .attrs()
             .filter_map(|x| x.as_simple_call())
             .filter(|(name, _arg)| name == "derive")
             .map(|(_name, arg)| arg)
             .next();
-        let offset = match derive_attr {
+        match derive_attr {
             None => {
-                edit.insert(node_start, "#[derive()]\n");
-                node_start + TextSize::of("#[derive(")
+                builder.insert_snippet(cap, node_start, "#[derive($0)]\n");
+            }
+            Some(tt) => {
+                // Just move the cursor.
+                builder.insert_snippet(
+                    cap,
+                    tt.syntax().text_range().end() - TextSize::of(')'),
+                    "$0",
+                )
             }
-            Some(tt) => tt.syntax().text_range().end() - TextSize::of(')'),
         };
-        edit.target(nominal.syntax().text_range());
-        edit.set_cursor(offset)
     })
 }
 
@@ -57,20 +63,21 @@ fn derive_insertion_offset(nominal: &ast::NominalDef) -> Option<TextSize> {
 
 #[cfg(test)]
 mod tests {
+    use crate::tests::{check_assist, check_assist_target};
+
     use super::*;
-    use crate::helpers::{check_assist, check_assist_target};
 
     #[test]
     fn add_derive_new() {
         check_assist(
             add_derive,
             "struct Foo { a: i32, <|>}",
-            "#[derive(<|>)]\nstruct Foo { a: i32, }",
+            "#[derive($0)]\nstruct Foo { a: i32, }",
         );
         check_assist(
             add_derive,
             "struct Foo { <|> a: i32, }",
-            "#[derive(<|>)]\nstruct Foo {  a: i32, }",
+            "#[derive($0)]\nstruct Foo {  a: i32, }",
         );
     }
 
@@ -79,7 +86,7 @@ mod tests {
         check_assist(
             add_derive,
             "#[derive(Clone)]\nstruct Foo { a: i32<|>, }",
-            "#[derive(Clone<|>)]\nstruct Foo { a: i32, }",
+            "#[derive(Clone$0)]\nstruct Foo { a: i32, }",
         );
     }
 
@@ -95,7 +102,7 @@ struct Foo { a: i32<|>, }
             "
 /// `Foo` is a pretty important struct.
 /// It does stuff.
-#[derive(<|>)]
+#[derive($0)]
 struct Foo { a: i32, }
             ",
         );
diff --git a/crates/ra_assists/src/handlers/add_explicit_type.rs b/crates/ra_assists/src/handlers/add_explicit_type.rs
index bc313782b..ab20c6649 100644
--- a/crates/ra_assists/src/handlers/add_explicit_type.rs
+++ b/crates/ra_assists/src/handlers/add_explicit_type.rs
@@ -4,7 +4,7 @@ use ra_syntax::{
     TextRange,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: add_explicit_type
 //
@@ -21,12 +21,12 @@ use crate::{Assist, AssistCtx, AssistId};
 //     let x: i32 = 92;
 // }
 // ```
-pub(crate) fn add_explicit_type(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_explicit_type(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let stmt = ctx.find_node_at_offset::<LetStmt>()?;
+    let module = ctx.sema.scope(stmt.syntax()).module()?;
     let expr = stmt.initializer()?;
-    let pat = stmt.pat()?;
     // Must be a binding
-    let pat = match pat {
+    let pat = match stmt.pat()? {
         ast::Pat::BindPat(bind_pat) => bind_pat,
         _ => return None,
     };
@@ -45,7 +45,7 @@ pub(crate) fn add_explicit_type(ctx: AssistCtx) -> Option<Assist> {
     // Assist not applicable if the type has already been specified
     // and it has no placeholders
     let ascribed_ty = stmt.ascribed_type();
-    if let Some(ref ty) = ascribed_ty {
+    if let Some(ty) = &ascribed_ty {
         if ty.syntax().descendants().find_map(ast::PlaceholderType::cast).is_none() {
             return None;
         }
@@ -57,17 +57,17 @@ pub(crate) fn add_explicit_type(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
 
-    let db = ctx.db;
-    let new_type_string = ty.display_truncated(db, None).to_string();
-    ctx.add_assist(
+    let inferred_type = ty.display_source_code(ctx.db, module.into()).ok()?;
+    acc.add(
         AssistId("add_explicit_type"),
-        format!("Insert explicit type '{}'", new_type_string),
-        |edit| {
-            edit.target(pat_range);
-            if let Some(ascribed_ty) = ascribed_ty {
-                edit.replace(ascribed_ty.syntax().text_range(), new_type_string);
-            } else {
-                edit.insert(name_range.end(), format!(": {}", new_type_string));
+        format!("Insert explicit type `{}`", inferred_type),
+        pat_range,
+        |builder| match ascribed_ty {
+            Some(ascribed_ty) => {
+                builder.replace(ascribed_ty.syntax().text_range(), inferred_type);
+            }
+            None => {
+                builder.insert(name_range.end(), format!(": {}", inferred_type));
             }
         },
     )
@@ -77,7 +77,7 @@ pub(crate) fn add_explicit_type(ctx: AssistCtx) -> Option<Assist> {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn add_explicit_type_target() {
@@ -86,11 +86,7 @@ mod tests {
 
     #[test]
     fn add_explicit_type_works_for_simple_expr() {
-        check_assist(
-            add_explicit_type,
-            "fn f() { let a<|> = 1; }",
-            "fn f() { let a<|>: i32 = 1; }",
-        );
+        check_assist(add_explicit_type, "fn f() { let a<|> = 1; }", "fn f() { let a: i32 = 1; }");
     }
 
     #[test]
@@ -98,7 +94,7 @@ mod tests {
         check_assist(
             add_explicit_type,
             "fn f() { let a<|>: _ = 1; }",
-            "fn f() { let a<|>: i32 = 1; }",
+            "fn f() { let a: i32 = 1; }",
         );
     }
 
@@ -122,7 +118,7 @@ mod tests {
             }
 
             fn f() {
-                let a<|>: Option<i32> = Option::Some(1);
+                let a: Option<i32> = Option::Some(1);
             }"#,
         );
     }
@@ -132,7 +128,7 @@ mod tests {
         check_assist(
             add_explicit_type,
             r"macro_rules! v { () => {0u64} } fn f() { let a<|> = v!(); }",
-            r"macro_rules! v { () => {0u64} } fn f() { let a<|>: u64 = v!(); }",
+            r"macro_rules! v { () => {0u64} } fn f() { let a: u64 = v!(); }",
         );
     }
 
@@ -140,8 +136,8 @@ mod tests {
     fn add_explicit_type_works_for_macro_call_recursive() {
         check_assist(
             add_explicit_type,
-            "macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a<|> = v!(); }",
-            "macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a<|>: u64 = v!(); }",
+            r#"macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a<|> = v!(); }"#,
+            r#"macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a: u64 = v!(); }"#,
         );
     }
 
@@ -208,7 +204,7 @@ struct Test<K, T = u8> {
 }
 
 fn main() {
-    let test<|>: Test<i32> = Test { t: 23, k: 33 };
+    let test: Test<i32> = Test { t: 23, k: 33 };
 }"#,
         );
     }
diff --git a/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs b/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
index 49deb6701..6a675e812 100644
--- a/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
+++ b/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
@@ -1,12 +1,8 @@
 use ra_ide_db::RootDatabase;
-use ra_syntax::{
-    ast::{self, AstNode, NameOwner},
-    TextSize,
-};
-use stdx::format_to;
+use ra_syntax::ast::{self, AstNode, NameOwner};
+use test_utils::mark;
 
-use crate::{utils::FamousDefs, Assist, AssistCtx, AssistId};
-use test_utils::tested_by;
+use crate::{utils::FamousDefs, AssistContext, AssistId, Assists};
 
 // Assist add_from_impl_for_enum
 //
@@ -25,7 +21,7 @@ use test_utils::tested_by;
 //     }
 // }
 // ```
-pub(crate) fn add_from_impl_for_enum(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_from_impl_for_enum(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let variant = ctx.find_node_at_offset::<ast::EnumVariant>()?;
     let variant_name = variant.name()?;
     let enum_name = variant.parent_enum().name()?;
@@ -38,23 +34,23 @@ pub(crate) fn add_from_impl_for_enum(ctx: AssistCtx) -> Option<Assist> {
     }
     let field_type = field_list.fields().next()?.type_ref()?;
     let path = match field_type {
-        ast::TypeRef::PathType(p) => p,
+        ast::TypeRef::PathType(it) => it,
         _ => return None,
     };
 
-    if existing_from_impl(ctx.sema, &variant).is_some() {
-        tested_by!(test_add_from_impl_already_exists);
+    if existing_from_impl(&ctx.sema, &variant).is_some() {
+        mark::hit!(test_add_from_impl_already_exists);
         return None;
     }
 
-    ctx.add_assist(
+    let target = variant.syntax().text_range();
+    acc.add(
         AssistId("add_from_impl_for_enum"),
         "Add From impl for this enum variant",
+        target,
         |edit| {
             let start_offset = variant.parent_enum().syntax().text_range().end();
-            let mut buf = String::new();
-            format_to!(
-                buf,
+            let buf = format!(
                 r#"
 
 impl From<{0}> for {1} {{
@@ -67,7 +63,6 @@ impl From<{0}> for {1} {{
                 variant_name
             );
             edit.insert(start_offset, buf);
-            edit.set_cursor(start_offset + TextSize::of("\n\n"));
         },
     )
 }
@@ -95,10 +90,11 @@ fn existing_from_impl(
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use test_utils::mark;
+
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
-    use crate::helpers::{check_assist, check_assist_not_applicable};
-    use test_utils::covers;
+    use super::*;
 
     #[test]
     fn test_add_from_impl_for_enum() {
@@ -107,7 +103,7 @@ mod tests {
             "enum A { <|>One(u32) }",
             r#"enum A { One(u32) }
 
-<|>impl From<u32> for A {
+impl From<u32> for A {
     fn from(v: u32) -> Self {
         A::One(v)
     }
@@ -119,10 +115,10 @@ mod tests {
     fn test_add_from_impl_for_enum_complicated_path() {
         check_assist(
             add_from_impl_for_enum,
-            "enum A { <|>One(foo::bar::baz::Boo) }",
+            r#"enum A { <|>One(foo::bar::baz::Boo) }"#,
             r#"enum A { One(foo::bar::baz::Boo) }
 
-<|>impl From<foo::bar::baz::Boo> for A {
+impl From<foo::bar::baz::Boo> for A {
     fn from(v: foo::bar::baz::Boo) -> Self {
         A::One(v)
     }
@@ -153,7 +149,7 @@ mod tests {
 
     #[test]
     fn test_add_from_impl_already_exists() {
-        covers!(test_add_from_impl_already_exists);
+        mark::check!(test_add_from_impl_already_exists);
         check_not_applicable(
             r#"
 enum A { <|>One(u32), }
@@ -184,7 +180,7 @@ pub trait From<T> {
 }"#,
             r#"enum A { One(u32), Two(String), }
 
-<|>impl From<u32> for A {
+impl From<u32> for A {
     fn from(v: u32) -> Self {
         A::One(v)
     }
diff --git a/crates/ra_assists/src/handlers/add_function.rs b/crates/ra_assists/src/handlers/add_function.rs
index 6c7456579..24f931a85 100644
--- a/crates/ra_assists/src/handlers/add_function.rs
+++ b/crates/ra_assists/src/handlers/add_function.rs
@@ -1,13 +1,21 @@
+use hir::HirDisplay;
+use ra_db::FileId;
 use ra_syntax::{
-    ast::{self, AstNode},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make, ArgListOwner, AstNode, ModuleItemOwner,
+    },
     SyntaxKind, SyntaxNode, TextSize,
 };
-
-use crate::{Assist, AssistCtx, AssistFile, AssistId};
-use ast::{edit::IndentLevel, ArgListOwner, ModuleItemOwner};
-use hir::HirDisplay;
 use rustc_hash::{FxHashMap, FxHashSet};
 
+use crate::{
+    assist_config::SnippetCap,
+    utils::{render_snippet, Cursor},
+    AssistContext, AssistId, Assists,
+};
+
 // Assist: add_function
 //
 // Adds a stub function with a signature matching the function under the cursor.
@@ -29,11 +37,11 @@ use rustc_hash::{FxHashMap, FxHashSet};
 // }
 //
 // fn bar(arg: &str, baz: Baz) {
-//     todo!()
+//     ${0:todo!()}
 // }
 //
 // ```
-pub(crate) fn add_function(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_function(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let path_expr: ast::PathExpr = ctx.find_node_at_offset()?;
     let call = path_expr.syntax().parent().and_then(ast::CallExpr::cast)?;
     let path = path_expr.path()?;
@@ -43,36 +51,49 @@ pub(crate) fn add_function(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
 
-    let target_module = if let Some(qualifier) = path.qualifier() {
-        if let Some(hir::PathResolution::Def(hir::ModuleDef::Module(module))) =
-            ctx.sema.resolve_path(&qualifier)
-        {
-            Some(module.definition_source(ctx.sema.db))
-        } else {
-            return None;
-        }
-    } else {
-        None
+    let target_module = match path.qualifier() {
+        Some(qualifier) => match ctx.sema.resolve_path(&qualifier) {
+            Some(hir::PathResolution::Def(hir::ModuleDef::Module(module))) => Some(module),
+            _ => return None,
+        },
+        None => None,
     };
 
     let function_builder = FunctionBuilder::from_call(&ctx, &call, &path, target_module)?;
 
-    ctx.add_assist(AssistId("add_function"), "Add function", |edit| {
-        edit.target(call.syntax().text_range());
-
-        if let Some(function_template) = function_builder.render() {
-            edit.set_file(function_template.file);
-            edit.set_cursor(function_template.cursor_offset);
-            edit.insert(function_template.insert_offset, function_template.fn_def.to_string());
+    let target = call.syntax().text_range();
+    acc.add(AssistId("add_function"), "Add function", target, |builder| {
+        let function_template = function_builder.render();
+        builder.set_file(function_template.file);
+        let new_fn = function_template.to_string(ctx.config.snippet_cap);
+        match ctx.config.snippet_cap {
+            Some(cap) => builder.insert_snippet(cap, function_template.insert_offset, new_fn),
+            None => builder.insert(function_template.insert_offset, new_fn),
         }
     })
 }
 
 struct FunctionTemplate {
     insert_offset: TextSize,
-    cursor_offset: TextSize,
-    fn_def: ast::SourceFile,
-    file: AssistFile,
+    placeholder_expr: ast::MacroCall,
+    leading_ws: String,
+    fn_def: ast::FnDef,
+    trailing_ws: String,
+    file: FileId,
+}
+
+impl FunctionTemplate {
+    fn to_string(&self, cap: Option<SnippetCap>) -> String {
+        let f = match cap {
+            Some(cap) => render_snippet(
+                cap,
+                self.fn_def.syntax(),
+                Cursor::Replace(self.placeholder_expr.syntax()),
+            ),
+            None => self.fn_def.to_string(),
+        };
+        format!("{}{}{}", self.leading_ws, f, self.trailing_ws)
+    }
 }
 
 struct FunctionBuilder {
@@ -80,68 +101,73 @@ struct FunctionBuilder {
     fn_name: ast::Name,
     type_params: Option<ast::TypeParamList>,
     params: ast::ParamList,
-    file: AssistFile,
+    file: FileId,
     needs_pub: bool,
 }
 
 impl FunctionBuilder {
-    /// Prepares a generated function that matches `call` in `generate_in`
-    /// (or as close to `call` as possible, if `generate_in` is `None`)
+    /// Prepares a generated function that matches `call`.
+    /// The function is generated in `target_module` or next to `call`
     fn from_call(
-        ctx: &AssistCtx,
+        ctx: &AssistContext,
         call: &ast::CallExpr,
         path: &ast::Path,
-        target_module: Option<hir::InFile<hir::ModuleSource>>,
+        target_module: Option<hir::Module>,
     ) -> Option<Self> {
-        let needs_pub = target_module.is_some();
-        let mut file = AssistFile::default();
-        let target = if let Some(target_module) = target_module {
-            let (in_file, target) = next_space_for_fn_in_module(ctx.sema.db, target_module)?;
-            file = in_file;
-            target
-        } else {
-            next_space_for_fn_after_call_site(&call)?
+        let mut file = ctx.frange.file_id;
+        let target = match &target_module {
+            Some(target_module) => {
+                let module_source = target_module.definition_source(ctx.db);
+                let (in_file, target) = next_space_for_fn_in_module(ctx.sema.db, &module_source)?;
+                file = in_file;
+                target
+            }
+            None => next_space_for_fn_after_call_site(&call)?,
         };
+        let needs_pub = target_module.is_some();
+        let target_module = target_module.or_else(|| ctx.sema.scope(target.syntax()).module())?;
         let fn_name = fn_name(&path)?;
-        let (type_params, params) = fn_args(ctx, &call)?;
+        let (type_params, params) = fn_args(ctx, target_module, &call)?;
+
         Some(Self { target, fn_name, type_params, params, file, needs_pub })
     }
 
-    fn render(self) -> Option<FunctionTemplate> {
-        let placeholder_expr = ast::make::expr_todo();
-        let fn_body = ast::make::block_expr(vec![], Some(placeholder_expr));
-        let mut fn_def = ast::make::fn_def(self.fn_name, self.type_params, self.params, fn_body);
-        if self.needs_pub {
-            fn_def = ast::make::add_pub_crate_modifier(fn_def);
-        }
+    fn render(self) -> FunctionTemplate {
+        let placeholder_expr = make::expr_todo();
+        let fn_body = make::block_expr(vec![], Some(placeholder_expr));
+        let visibility = if self.needs_pub { Some(make::visibility_pub_crate()) } else { None };
+        let mut fn_def =
+            make::fn_def(visibility, self.fn_name, self.type_params, self.params, fn_body);
+        let leading_ws;
+        let trailing_ws;
 
-        let (fn_def, insert_offset) = match self.target {
+        let insert_offset = match self.target {
             GeneratedFunctionTarget::BehindItem(it) => {
-                let with_leading_blank_line = ast::make::add_leading_newlines(2, fn_def);
-                let indented = IndentLevel::from_node(&it).increase_indent(with_leading_blank_line);
-                (indented, it.text_range().end())
+                let indent = IndentLevel::from_node(&it);
+                leading_ws = format!("\n\n{}", indent);
+                fn_def = fn_def.indent(indent);
+                trailing_ws = String::new();
+                it.text_range().end()
             }
             GeneratedFunctionTarget::InEmptyItemList(it) => {
-                let indent_once = IndentLevel(1);
                 let indent = IndentLevel::from_node(it.syntax());
-
-                let fn_def = ast::make::add_leading_newlines(1, fn_def);
-                let fn_def = indent_once.increase_indent(fn_def);
-                let fn_def = ast::make::add_trailing_newlines(1, fn_def);
-                let fn_def = indent.increase_indent(fn_def);
-                (fn_def, it.syntax().text_range().start() + TextSize::of('{'))
+                leading_ws = format!("\n{}", indent + 1);
+                fn_def = fn_def.indent(indent + 1);
+                trailing_ws = format!("\n{}", indent);
+                it.syntax().text_range().start() + TextSize::of('{')
             }
         };
 
-        let cursor_offset_from_fn_start = fn_def
-            .syntax()
-            .descendants()
-            .find_map(ast::MacroCall::cast)?
-            .syntax()
-            .text_range()
-            .start();
-        let cursor_offset = insert_offset + cursor_offset_from_fn_start;
-        Some(FunctionTemplate { insert_offset, cursor_offset, fn_def, file: self.file })
+        let placeholder_expr =
+            fn_def.syntax().descendants().find_map(ast::MacroCall::cast).unwrap();
+        FunctionTemplate {
+            insert_offset,
+            placeholder_expr,
+            leading_ws,
+            fn_def,
+            trailing_ws,
+            file: self.file,
+        }
     }
 }
 
@@ -150,32 +176,41 @@ enum GeneratedFunctionTarget {
     InEmptyItemList(ast::ItemList),
 }
 
+impl GeneratedFunctionTarget {
+    fn syntax(&self) -> &SyntaxNode {
+        match self {
+            GeneratedFunctionTarget::BehindItem(it) => it,
+            GeneratedFunctionTarget::InEmptyItemList(it) => it.syntax(),
+        }
+    }
+}
+
 fn fn_name(call: &ast::Path) -> Option<ast::Name> {
     let name = call.segment()?.syntax().to_string();
-    Some(ast::make::name(&name))
+    Some(make::name(&name))
 }
 
 /// Computes the type variables and arguments required for the generated function
 fn fn_args(
-    ctx: &AssistCtx,
+    ctx: &AssistContext,
+    target_module: hir::Module,
     call: &ast::CallExpr,
 ) -> Option<(Option<ast::TypeParamList>, ast::ParamList)> {
     let mut arg_names = Vec::new();
     let mut arg_types = Vec::new();
     for arg in call.arg_list()?.args() {
-        let arg_name = match fn_arg_name(&arg) {
+        arg_names.push(match fn_arg_name(&arg) {
             Some(name) => name,
             None => String::from("arg"),
-        };
-        arg_names.push(arg_name);
-        arg_types.push(match fn_arg_type(ctx, &arg) {
+        });
+        arg_types.push(match fn_arg_type(ctx, target_module, &arg) {
             Some(ty) => ty,
             None => String::from("()"),
         });
     }
     deduplicate_arg_names(&mut arg_names);
-    let params = arg_names.into_iter().zip(arg_types).map(|(name, ty)| ast::make::param(name, ty));
-    Some((None, ast::make::param_list(params)))
+    let params = arg_names.into_iter().zip(arg_types).map(|(name, ty)| make::param(name, ty));
+    Some((None, make::param_list(params)))
 }
 
 /// Makes duplicate argument names unique by appending incrementing numbers.
@@ -224,12 +259,21 @@ fn fn_arg_name(fn_arg: &ast::Expr) -> Option<String> {
     }
 }
 
-fn fn_arg_type(ctx: &AssistCtx, fn_arg: &ast::Expr) -> Option<String> {
+fn fn_arg_type(
+    ctx: &AssistContext,
+    target_module: hir::Module,
+    fn_arg: &ast::Expr,
+) -> Option<String> {
     let ty = ctx.sema.type_of_expr(fn_arg)?;
     if ty.is_unknown() {
         return None;
     }
-    Some(ty.display(ctx.sema.db).to_string())
+
+    if let Ok(rendered) = ty.display_source_code(ctx.db, target_module.into()) {
+        Some(rendered)
+    } else {
+        None
+    }
 }
 
 /// Returns the position inside the current mod or file
@@ -258,11 +302,10 @@ fn next_space_for_fn_after_call_site(expr: &ast::CallExpr) -> Option<GeneratedFu
 
 fn next_space_for_fn_in_module(
     db: &dyn hir::db::AstDatabase,
-    module: hir::InFile<hir::ModuleSource>,
-) -> Option<(AssistFile, GeneratedFunctionTarget)> {
-    let file = module.file_id.original_file(db);
-    let assist_file = AssistFile::TargetFile(file);
-    let assist_item = match module.value {
+    module_source: &hir::InFile<hir::ModuleSource>,
+) -> Option<(FileId, GeneratedFunctionTarget)> {
+    let file = module_source.file_id.original_file(db);
+    let assist_item = match &module_source.value {
         hir::ModuleSource::SourceFile(it) => {
             if let Some(last_item) = it.items().last() {
                 GeneratedFunctionTarget::BehindItem(last_item.syntax().clone())
@@ -278,12 +321,12 @@ fn next_space_for_fn_in_module(
             }
         }
     };
-    Some((assist_file, assist_item))
+    Some((file, assist_item))
 }
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
@@ -302,7 +345,7 @@ fn foo() {
 }
 
 fn bar() {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -329,7 +372,7 @@ impl Foo {
 }
 
 fn bar() {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -353,7 +396,7 @@ fn foo1() {
 }
 
 fn bar() {
-    <|>todo!()
+    ${0:todo!()}
 }
 
 fn foo2() {}
@@ -379,7 +422,7 @@ mod baz {
     }
 
     fn bar() {
-        <|>todo!()
+        ${0:todo!()}
     }
 }
 ",
@@ -405,7 +448,7 @@ fn foo() {
 }
 
 fn bar(baz: Baz) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         );
@@ -438,7 +481,7 @@ impl Baz {
 }
 
 fn bar(baz: Baz) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -459,7 +502,7 @@ fn foo() {
 }
 
 fn bar(arg: &str) {
-    <|>todo!()
+    ${0:todo!()}
 }
 "#,
         )
@@ -480,7 +523,7 @@ fn foo() {
 }
 
 fn bar(arg: char) {
-    <|>todo!()
+    ${0:todo!()}
 }
 "#,
         )
@@ -501,7 +544,7 @@ fn foo() {
 }
 
 fn bar(arg: i32) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -522,7 +565,7 @@ fn foo() {
 }
 
 fn bar(arg: u8) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -547,7 +590,7 @@ fn foo() {
 }
 
 fn bar(x: u8) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -570,7 +613,7 @@ fn foo() {
 }
 
 fn bar(worble: ()) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -599,15 +642,40 @@ fn baz() {
 }
 
 fn bar(foo: impl Foo) {
-    <|>todo!()
+    ${0:todo!()}
+}
+",
+        )
+    }
+
+    #[test]
+    fn borrowed_arg() {
+        check_assist(
+            add_function,
+            r"
+struct Baz;
+fn baz() -> Baz { todo!() }
+
+fn foo() {
+    bar<|>(&baz())
+}
+",
+            r"
+struct Baz;
+fn baz() -> Baz { todo!() }
+
+fn foo() {
+    bar(&baz())
+}
+
+fn bar(baz: &Baz) {
+    ${0:todo!()}
 }
 ",
         )
     }
 
     #[test]
-    #[ignore]
-    // FIXME print paths properly to make this test pass
     fn add_function_with_qualified_path_arg() {
         check_assist(
             add_function,
@@ -616,10 +684,8 @@ mod Baz {
     pub struct Bof;
     pub fn baz() -> Bof { Bof }
 }
-mod Foo {
-    fn foo() {
-        <|>bar(super::Baz::baz())
-    }
+fn foo() {
+    <|>bar(Baz::baz())
 }
 ",
             r"
@@ -627,14 +693,12 @@ mod Baz {
     pub struct Bof;
     pub fn baz() -> Bof { Bof }
 }
-mod Foo {
-    fn foo() {
-        bar(super::Baz::baz())
-    }
+fn foo() {
+    bar(Baz::baz())
+}
 
-    fn bar(baz: super::Baz::Bof) {
-        <|>todo!()
-    }
+fn bar(baz: Baz::Bof) {
+    ${0:todo!()}
 }
 ",
         )
@@ -657,7 +721,7 @@ fn foo<T>(t: T) {
 }
 
 fn bar<T>(t: T) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -688,7 +752,7 @@ fn foo() {
 }
 
 fn bar(arg: fn() -> Baz) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -713,7 +777,7 @@ fn foo() {
 }
 
 fn bar(closure: impl Fn(i64) -> i64) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -734,7 +798,7 @@ fn foo() {
 }
 
 fn bar(baz: ()) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -759,7 +823,7 @@ fn foo() {
 }
 
 fn bar(baz_1: Baz, baz_2: Baz) {
-    <|>todo!()
+    ${0:todo!()}
 }
 ",
         )
@@ -784,7 +848,7 @@ fn foo() {
 }
 
 fn bar(baz_1: Baz, baz_2: Baz, arg_1: &str, arg_2: &str) {
-    <|>todo!()
+    ${0:todo!()}
 }
 "#,
         )
@@ -804,7 +868,7 @@ fn foo() {
             r"
 mod bar {
     pub(crate) fn my_fn() {
-        <|>todo!()
+        ${0:todo!()}
     }
 }
 
@@ -816,6 +880,40 @@ fn foo() {
     }
 
     #[test]
+    #[ignore]
+    // Ignored until local imports are supported.
+    // See https://github.com/rust-analyzer/rust-analyzer/issues/1165
+    fn qualified_path_uses_correct_scope() {
+        check_assist(
+            add_function,
+            "
+mod foo {
+    pub struct Foo;
+}
+fn bar() {
+    use foo::Foo;
+    let foo = Foo;
+    baz<|>(foo)
+}
+",
+            "
+mod foo {
+    pub struct Foo;
+}
+fn bar() {
+    use foo::Foo;