24 files changed, 366 insertions, 142 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 2557b5e59..83e41940b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -187,16 +187,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "chrono"
-version = "0.4.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "num-integer 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "time 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
 name = "clicolors-control"
 version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -324,6 +314,15 @@ version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "env_logger"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "humantime 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "filetime"
 version = "0.2.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -340,18 +339,6 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
-name = "flexi_logger"
-version = "0.14.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "chrono 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "glob 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "yansi 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
 name = "fnv"
 version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -421,11 +408,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "glob"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
 name = "globset"
 version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -454,6 +436,14 @@ dependencies = [
 ]
 
 [[package]]
+name = "humantime"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "quick-error 1.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "idna"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -723,15 +713,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "num-integer"
-version = "0.1.41"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "autocfg 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
 name = "num-traits"
 version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -928,7 +909,7 @@ dependencies = [
 name = "ra_cli"
 version = "0.1.0"
 dependencies = [
- "flexi_logger 0.14.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "env_logger 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "pico-args 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_batch 0.1.0",
  "ra_db 0.1.0",
@@ -1060,7 +1041,7 @@ name = "ra_lsp_server"
 version = "0.1.0"
 dependencies = [
  "crossbeam-channel 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "flexi_logger 0.14.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "env_logger 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "jod-thread 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "lsp-server 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1648,16 +1629,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "time"
-version = "0.1.42"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "libc 0.2.65 (registry+https://github.com/rust-lang/crates.io-index)",
- "redox_syscall 0.1.56 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
 name = "unicase"
 version = "2.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1798,11 +1769,6 @@ dependencies = [
  "linked-hash-map 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "yansi"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [metadata]
 "checksum aho-corasick 0.7.6 (registry+https://github.com/rust-lang/crates.io-index)" = "58fb5e95d83b38284460a5fda7d6470aa0b8844d283a0b614b8535e880800d2d"
 "checksum anyhow 1.0.24 (registry+https://github.com/rust-lang/crates.io-index)" = "b412394828b7ca486b362f300b762d8e43dafd6f0d727b63f1cd2ade207c6cef"
@@ -1827,7 +1793,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum chalk-macros 0.1.1 (git+https://github.com/jackh726/chalk.git?rev=095cd38a4f16337913bba487f2055b9ca0179f30)" = "<none>"
 "checksum chalk-rust-ir 0.1.0 (git+https://github.com/jackh726/chalk.git?rev=095cd38a4f16337913bba487f2055b9ca0179f30)" = "<none>"
 "checksum chalk-solve 0.1.0 (git+https://github.com/jackh726/chalk.git?rev=095cd38a4f16337913bba487f2055b9ca0179f30)" = "<none>"
-"checksum chrono 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)" = "31850b4a4d6bae316f7a09e691c944c28299298837edc0a03f755618c23cbc01"
 "checksum clicolors-control 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "90082ee5dcdd64dc4e9e0d37fbf3ee325419e39c0092191e0393df65518f741e"
 "checksum cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
 "checksum console 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)" = "f5d540c2d34ac9dd0deb5f3b5f54c36c79efa78f6b3ad19106a554d07a7b5d9f"
@@ -1843,9 +1808,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum either 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "bb1f6b1ce1c140482ea30ddd3335fc0024ac7ee112895426e0a629a6c20adfe3"
 "checksum ena 0.13.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8944dc8fa28ce4a38f778bd46bf7d923fe73eed5a439398507246c8e017e6f36"
 "checksum encode_unicode 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "a357d28ed41a50f9c765dbfe56cbc04a64e53e5fc58ba79fbc34c10ef3df831f"
+"checksum env_logger 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "44533bbbb3bb3c1fa17d9f2e4e38bbbaf8396ba82193c4cb1b6445d711445d36"
 "checksum filetime 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)" = "1ff6d4dab0aa0c8e6346d46052e93b13a16cf847b54ed357087c35011048cc7d"
 "checksum fixedbitset 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "86d4de0081402f5e88cdac65c8dcdcc73118c1a7a465e2a05f0da05843a8ea33"
-"checksum flexi_logger 0.14.5 (registry+https://github.com/rust-lang/crates.io-index)" = "a13ea6b8a4debecf47bf3966d56db0e21366bc3a3649ba159e1a9e6fdd36a4f4"
 "checksum fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
 "checksum format-buf 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f7aea5a5909a74969507051a3b17adc84737e31a5f910559892aedce026f4d53"
 "checksum fs_extra 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5f2a4a2034423744d2cc7ca2068453168dcdb82c438419e639a26bd87839c674"
@@ -1856,10 +1821,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "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 getrandom 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "e7db7ca94ed4cd01190ceee0d8a8052f08a247aa1b469a7f68c6a3b71afcf407"
-"checksum glob 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9b919933a397b79c37e33b77bb2aa3dc8eb6e165ad809e58ff75bc7db2e34574"
 "checksum globset 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)" = "925aa2cac82d8834e2b2a4415b6f6879757fb5c0928fc445ae76461a12eed8f2"
 "checksum heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "20564e78d53d2bb135c343b3f47714a56af2061f1c928fdb541dc7b9fdd94205"
 "checksum hermit-abi 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "307c3c9f937f38e3534b1d6447ecf090cafcc9744e4a6360e8b037b2cf5af120"
+"checksum humantime 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "df004cfca50ef23c36850aaaa59ad52cc70d0e90243c3c7737a4dd32dc7a3c4f"
 "checksum idna 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "02e2673c30ee86b5b96a9cb52ad15718aa1f966f5ab9ad54a8b95d5ca33120a9"
 "checksum indexmap 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712d7b3ea5827fcb9d4fda14bf4da5f136f0db2ae9c8f4bd4e2d1c6fde4e6db2"
 "checksum inotify 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)" = "40b54539f3910d6f84fbf9a643efd6e3aa6e4f001426c0329576128255994718"
@@ -1891,7 +1856,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum miow 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8c1f2f3b1cf331de6896aabf6e9d55dca90356cc9960cca7eaaf408a355ae919"
 "checksum net2 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)" = "42550d9fb7b6684a6d404d9fa7250c2eb2646df731d1c06afc06dcee9e1bcf88"
 "checksum notify 4.0.14 (registry+https://github.com/rust-lang/crates.io-index)" = "199628fc33b21bc767baa057490b00b382ecbae030803a7b36292422d15b778b"
-"checksum num-integer 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)" = "b85e541ef8255f6cf42bbfe4ef361305c6c135d10919ecc26126c4e5ae94bc09"
 "checksum num-traits 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)" = "d4c81ffc11c212fa327657cb19dd85eb7419e163b5b076bede2bdb5c974c07e4"
 "checksum num_cpus 1.11.1 (registry+https://github.com/rust-lang/crates.io-index)" = "76dac5ed2a876980778b8b85f75a71b6cbf0db0b1232ee12f826bccb00d09d72"
 "checksum once_cell 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "891f486f630e5c5a4916c7e16c4b24a53e78c860b646e9f8e005e4f16847bfed"
@@ -1964,7 +1928,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum thin-dst 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c52fd98a9e4913c466d83381a59245691875d2f3e04611fca57f964bd8aa96e1"
 "checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"
 "checksum threadpool 1.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e2f0c90a5f3459330ac8bc0d2f879c693bb7a2f59689c1083fc4ef83834da865"
-"checksum time 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)" = "db8dcfca086c1143c9270ac42a2bbd8a7ee477b78ac8e45b19abfb0cbede4b6f"
 "checksum unicase 2.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "50f37be617794602aabbeee0be4f259dc1778fabe05e2d67ee8f79326d5cb4f6"
 "checksum unicode-bidi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "49f2bd0c6468a8230e1db229cff8029217cf623c767ea5d60bfbd42729ea54d5"
 "checksum unicode-normalization 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)" = "b561e267b2326bb4cebfc0ef9e68355c7abe6c6f522aeac2f5bf95d56c59bdcf"
@@ -1983,4 +1946,3 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 "checksum ws2_32-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "d59cefebd0c892fa2dd6de581e937301d8552cb44489cdff035c6187cb63fa5e"
 "checksum yaml-rust 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "65923dd1784f44da1d2c3dbbc5e822045628c590ba72123e1c73d3c230c4434d"
-"checksum yansi 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9fc79f4a1e39857fc00c3f662cbf2651c771f00e9c15fe2abc341806bd46bd71"
diff --git a/crates/ra_cli/Cargo.toml b/crates/ra_cli/Cargo.toml
index c7e0d0f0f..21a37c7bf 100644
--- a/crates/ra_cli/Cargo.toml
+++ b/crates/ra_cli/Cargo.toml
@@ -7,7 +7,7 @@ publish = false
 
 [dependencies]
 pico-args = "0.3.0"
-flexi_logger = "0.14.0"
+env_logger = { version = "0.7.1", default-features = false, features = ["humantime"] }
 
 ra_syntax = { path = "../ra_syntax" }
 ra_ide = { path = "../ra_ide" }
diff --git a/crates/ra_cli/src/main.rs b/crates/ra_cli/src/main.rs
index fe847e611..3808590ab 100644
--- a/crates/ra_cli/src/main.rs
+++ b/crates/ra_cli/src/main.rs
@@ -7,7 +7,6 @@ mod progress_report;
 
 use std::{error::Error, fmt::Write, io::Read};
 
-use flexi_logger::Logger;
 use pico_args::Arguments;
 use ra_ide::{file_structure, Analysis};
 use ra_prof::profile;
@@ -32,7 +31,7 @@ impl Verbosity {
 }
 
 fn main() -> Result<()> {
-    Logger::with_env_or_str("error").start()?;
+    env_logger::try_init()?;
 
     let subcommand = match std::env::args_os().nth(1) {
         None => {
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index 331736cb2..be1eaa523 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -429,10 +429,19 @@ where
                 let index = self.collect_expr_opt(e.index());
                 self.alloc_expr(Expr::Index { base, index }, syntax_ptr)
             }
+            ast::Expr::RangeExpr(e) => {
+                let lhs = e.start().map(|lhs| self.collect_expr(lhs));
+                let rhs = e.end().map(|rhs| self.collect_expr(rhs));
+                match e.op_kind() {
+                    Some(range_type) => {
+                        self.alloc_expr(Expr::Range { lhs, rhs, range_type }, syntax_ptr)
+                    }
+                    None => self.alloc_expr(Expr::Missing, syntax_ptr),
+                }
+            }
 
             // FIXME implement HIR for these:
             ast::Expr::Label(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
-            ast::Expr::RangeExpr(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
             ast::Expr::MacroCall(e) => match self.expander.enter_expand(self.db, e) {
                 Some((mark, expansion)) => {
                     let id = self.collect_expr(expansion);
diff --git a/crates/ra_hir_def/src/expr.rs b/crates/ra_hir_def/src/expr.rs
index 04c1d8f69..6fad80a8d 100644
--- a/crates/ra_hir_def/src/expr.rs
+++ b/crates/ra_hir_def/src/expr.rs
@@ -14,6 +14,7 @@
 
 use hir_expand::name::Name;
 use ra_arena::{impl_arena_id, RawId};
+use ra_syntax::ast::RangeOp;
 
 use crate::{
     builtin_type::{BuiltinFloat, BuiltinInt},
@@ -130,6 +131,11 @@ pub enum Expr {
         rhs: ExprId,
         op: Option<BinaryOp>,
     },
+    Range {
+        lhs: Option<ExprId>,
+        rhs: Option<ExprId>,
+        range_type: RangeOp,
+    },
     Index {
         base: ExprId,
         index: ExprId,
@@ -288,6 +294,14 @@ impl Expr {
                 f(*lhs);
                 f(*rhs);
             }
+            Expr::Range { lhs, rhs, .. } => {
+                if let Some(lhs) = rhs {
+                    f(*lhs);
+                }
+                if let Some(rhs) = lhs {
+                    f(*rhs);
+                }
+            }
             Expr::Index { base, index } => {
                 f(*base);
                 f(*index);
diff --git a/crates/ra_hir_def/src/path.rs b/crates/ra_hir_def/src/path.rs
index 10688df4d..ff252fe44 100644
--- a/crates/ra_hir_def/src/path.rs
+++ b/crates/ra_hir_def/src/path.rs
@@ -409,6 +409,36 @@ pub mod known {
         Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::TRY_TYPE])
     }
 
+    pub fn std_ops_range() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::RANGE_TYPE])
+    }
+
+    pub fn std_ops_range_from() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::RANGE_FROM_TYPE])
+    }
+
+    pub fn std_ops_range_full() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::RANGE_FULL_TYPE])
+    }
+
+    pub fn std_ops_range_inclusive() -> Path {
+        Path::from_simple_segments(
+            PathKind::Abs,
+            vec![name::STD, name::OPS, name::RANGE_INCLUSIVE_TYPE],
+        )
+    }
+
+    pub fn std_ops_range_to() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::RANGE_TO_TYPE])
+    }
+
+    pub fn std_ops_range_to_inclusive() -> Path {
+        Path::from_simple_segments(
+            PathKind::Abs,
+            vec![name::STD, name::OPS, name::RANGE_TO_INCLUSIVE_TYPE],
+        )
+    }
+
     pub fn std_result_result() -> Path {
         Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::RESULT, name::RESULT_TYPE])
     }
diff --git a/crates/ra_hir_expand/src/name.rs b/crates/ra_hir_expand/src/name.rs
index 7824489d7..05ba37070 100644
--- a/crates/ra_hir_expand/src/name.rs
+++ b/crates/ra_hir_expand/src/name.rs
@@ -140,6 +140,12 @@ pub const RESULT_TYPE: Name = Name::new_inline_ascii(6, b"Result");
 pub const OUTPUT_TYPE: Name = Name::new_inline_ascii(6, b"Output");
 pub const TARGET_TYPE: Name = Name::new_inline_ascii(6, b"Target");
 pub const BOX_TYPE: Name = Name::new_inline_ascii(3, b"Box");
+pub const RANGE_FROM_TYPE: Name = Name::new_inline_ascii(9, b"RangeFrom");
+pub const RANGE_FULL_TYPE: Name = Name::new_inline_ascii(9, b"RangeFull");
+pub const RANGE_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(14, b"RangeInclusive");
+pub const RANGE_TO_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(16, b"RangeToInclusive");
+pub const RANGE_TO_TYPE: Name = Name::new_inline_ascii(7, b"RangeTo");
+pub const RANGE_TYPE: Name = Name::new_inline_ascii(5, b"Range");
 
 // Builtin Macros
 pub const FILE_MACRO: Name = Name::new_inline_ascii(4, b"file");
diff --git a/crates/ra_hir_ty/src/db.rs b/crates/ra_hir_ty/src/db.rs
index 9ce154593..222a36a9f 100644
--- a/crates/ra_hir_ty/src/db.rs
+++ b/crates/ra_hir_ty/src/db.rs
@@ -11,7 +11,7 @@ use ra_db::{salsa, CrateId};
 use crate::{
     method_resolution::CrateImplBlocks,
     traits::{AssocTyValue, Impl},
-    CallableDef, FnSig, GenericPredicate, ImplTy, InferenceResult, Substs, Ty, TyDefId, TypeCtor,
+    CallableDef, FnSig, GenericPredicate, InferenceResult, Substs, TraitRef, Ty, TyDefId, TypeCtor,
     ValueTyDefId,
 };
 
@@ -22,13 +22,18 @@ pub trait HirDatabase: DefDatabase {
     fn infer(&self, def: DefWithBodyId) -> Arc<InferenceResult>;
 
     #[salsa::invoke(crate::lower::ty_query)]
+    #[salsa::cycle(crate::lower::ty_recover)]
     fn ty(&self, def: TyDefId) -> Ty;
 
     #[salsa::invoke(crate::lower::value_ty_query)]
     fn value_ty(&self, def: ValueTyDefId) -> Ty;
 
-    #[salsa::invoke(crate::lower::impl_ty_query)]
-    fn impl_ty(&self, def: ImplId) -> ImplTy;
+    #[salsa::invoke(crate::lower::impl_self_ty_query)]
+    #[salsa::cycle(crate::lower::impl_self_ty_recover)]
+    fn impl_self_ty(&self, def: ImplId) -> Ty;
+
+    #[salsa::invoke(crate::lower::impl_trait_query)]
+    fn impl_trait(&self, def: ImplId) -> Option<TraitRef>;
 
     #[salsa::invoke(crate::lower::field_types_query)]
     fn field_types(&self, var: VariantId) -> Arc<ArenaMap<LocalStructFieldId, Ty>>;
@@ -37,6 +42,7 @@ pub trait HirDatabase: DefDatabase {
     fn callable_item_signature(&self, def: CallableDef) -> FnSig;
 
     #[salsa::invoke(crate::lower::generic_predicates_for_param_query)]
+    #[salsa::cycle(crate::lower::generic_predicates_for_param_recover)]
     fn generic_predicates_for_param(
         &self,
         def: GenericDefId,
diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index f6283ab6d..fe259371f 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -577,6 +577,42 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
         Some(struct_.into())
     }
+
+    fn resolve_range_full(&self) -> Option<AdtId> {
+        let path = known::std_ops_range_full();
+        let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
+        Some(struct_.into())
+    }
+
+    fn resolve_range(&self) -> Option<AdtId> {
+        let path = known::std_ops_range();
+        let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
+        Some(struct_.into())
+    }
+
+    fn resolve_range_inclusive(&self) -> Option<AdtId> {
+        let path = known::std_ops_range_inclusive();
+        let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
+        Some(struct_.into())
+    }
+
+    fn resolve_range_from(&self) -> Option<AdtId> {
+        let path = known::std_ops_range_from();
+        let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
+        Some(struct_.into())
+    }
+
+    fn resolve_range_to(&self) -> Option<AdtId> {
+        let path = known::std_ops_range_to();
+        let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
+        Some(struct_.into())
+    }
+
+    fn resolve_range_to_inclusive(&self) -> Option<AdtId> {
+        let path = known::std_ops_range_to_inclusive();
+        let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
+        Some(struct_.into())
+    }
 }
 
 /// The ID of a type variable.
diff --git a/crates/ra_hir_ty/src/infer/coerce.rs b/crates/ra_hir_ty/src/infer/coerce.rs
index 719a0f395..064993d34 100644
--- a/crates/ra_hir_ty/src/infer/coerce.rs
+++ b/crates/ra_hir_ty/src/infer/coerce.rs
@@ -8,7 +8,7 @@ use hir_def::{lang_item::LangItemTarget, resolver::Resolver, type_ref::Mutabilit
 use rustc_hash::FxHashMap;
 use test_utils::tested_by;
 
-use crate::{autoderef, db::HirDatabase, ImplTy, Substs, Ty, TypeCtor, TypeWalk};
+use crate::{autoderef, db::HirDatabase, Substs, Ty, TypeCtor, TypeWalk};
 
 use super::{InEnvironment, InferTy, InferenceContext, TypeVarValue};
 
@@ -54,10 +54,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         impls
             .iter()
             .filter_map(|&impl_id| {
-                let trait_ref = match db.impl_ty(impl_id) {
-                    ImplTy::TraitRef(it) => it,
-                    ImplTy::Inherent(_) => return None,
-                };
+                let trait_ref = db.impl_trait(impl_id)?;
 
                 // `CoerseUnsized` has one generic parameter for the target type.
                 let cur_from_ty = trait_ref.substs.0.get(0)?;
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 2f9ca4bbb..4014f4732 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -12,6 +12,7 @@ use hir_def::{
     AdtId, ContainerId, Lookup, StructFieldId,
 };
 use hir_expand::name::{self, Name};
+use ra_syntax::ast::RangeOp;
 
 use crate::{
     autoderef, db::HirDatabase, method_resolution, op, traits::InEnvironment, utils::variant_data,
@@ -415,6 +416,44 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 }
                 _ => Ty::Unknown,
             },
+            Expr::Range { lhs, rhs, range_type } => {
+                let lhs_ty = lhs.map(|e| self.infer_expr(e, &Expectation::none()));
+                let rhs_expect = lhs_ty
+                    .as_ref()
+                    .map_or_else(Expectation::none, |ty| Expectation::has_type(ty.clone()));
+                let rhs_ty = rhs.map(|e| self.infer_expr(e, &rhs_expect));
+                match (range_type, lhs_ty, rhs_ty) {
+                    (RangeOp::Exclusive, None, None) => match self.resolve_range_full() {
+                        Some(adt) => Ty::simple(TypeCtor::Adt(adt)),
+                        None => Ty::Unknown,
+                    },
+                    (RangeOp::Exclusive, None, Some(ty)) => match self.resolve_range_to() {
+                        Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
+                        None => Ty::Unknown,
+                    },
+                    (RangeOp::Inclusive, None, Some(ty)) => {
+                        match self.resolve_range_to_inclusive() {
+                            Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
+                            None => Ty::Unknown,
+                        }
+                    }
+                    (RangeOp::Exclusive, Some(_), Some(ty)) => match self.resolve_range() {
+                        Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
+                        None => Ty::Unknown,
+                    },
+                    (RangeOp::Inclusive, Some(_), Some(ty)) => {
+                        match self.resolve_range_inclusive() {
+                            Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
+                            None => Ty::Unknown,
+                        }
+                    }
+                    (RangeOp::Exclusive, Some(ty), None) => match self.resolve_range_from() {
+                        Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
+                        None => Ty::Unknown,
+                    },
+                    (RangeOp::Inclusive, _, None) => Ty::Unknown,
+                }
+            }
             Expr::Index { base, index } => {
                 let _base_ty = self.infer_expr(*base, &Expectation::none());
                 let _index_ty = self.infer_expr(*index, &Expectation::none());
diff --git a/crates/ra_hir_ty/src/infer/path.rs b/crates/ra_hir_ty/src/infer/path.rs
index 14be66836..bbf146418 100644
--- a/crates/ra_hir_ty/src/infer/path.rs
+++ b/crates/ra_hir_ty/src/infer/path.rs
@@ -244,7 +244,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 ContainerId::ImplId(it) => it,
                 _ => return None,
             };
-            let self_ty = self.db.impl_ty(impl_id).self_type().clone();
+            let self_ty = self.db.impl_self_ty(impl_id).clone();
             let self_ty_substs = self_ty.substs()?;
             let actual_substs = actual_def_ty.substs()?;
 
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index b45c8f82f..3c1f738df 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -486,21 +486,6 @@ impl TypeWalk for TraitRef {
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug)]
-pub enum ImplTy {
-    Inherent(Ty),
-    TraitRef(TraitRef),
-}
-
-impl ImplTy {
-    pub(crate) fn self_type(&self) -> &Ty {
-        match self {
-            ImplTy::Inherent(it) => it,
-            ImplTy::TraitRef(tr) => &tr.substs[0],
-        }
-    }
-}
-
 /// Like `generics::WherePredicate`, but with resolved types: A condition on the
 /// parameters of a generic item.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index 091c60f4f..32569ac66 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -27,8 +27,8 @@ use crate::{
         all_super_traits, associated_type_by_name_including_super_traits, make_mut_slice,
         variant_data,
     },
-    FnSig, GenericPredicate, ImplTy, ProjectionPredicate, ProjectionTy, Substs, TraitEnvironment,
-    TraitRef, Ty, TypeCtor, TypeWalk,
+    FnSig, GenericPredicate, ProjectionPredicate, ProjectionTy, Substs, TraitEnvironment, TraitRef,
+    Ty, TypeCtor, TypeWalk,
 };
 
 impl Ty {
@@ -179,7 +179,7 @@ impl Ty {
                 let name = resolved_segment.name.clone();
                 Ty::Param { idx, name }
             }
-            TypeNs::SelfType(impl_id) => db.impl_ty(impl_id).self_type().clone(),
+            TypeNs::SelfType(impl_id) => db.impl_self_ty(impl_id).clone(),
             TypeNs::AdtSelfType(adt) => db.ty(adt.into()),
 
             TypeNs::AdtId(it) => Ty::from_hir_path_inner(db, resolver, resolved_segment, it.into()),
@@ -532,6 +532,15 @@ pub(crate) fn generic_predicates_for_param_query(
         .collect()
 }
 
+pub(crate) fn generic_predicates_for_param_recover(
+    _db: &impl HirDatabase,
+    _cycle: &[String],
+    _def: &GenericDefId,
+    _param_idx: &u32,
+) -> Arc<[GenericPredicate]> {
+    Arc::new([])
+}
+
 impl TraitEnvironment {
     pub fn lower(db: &impl HirDatabase, resolver: &Resolver) -> Arc<TraitEnvironment> {
         let predicates = resolver
@@ -733,6 +742,11 @@ pub(crate) fn ty_query(db: &impl HirDatabase, def: TyDefId) -> Ty {
         TyDefId::TypeAliasId(it) => type_for_type_alias(db, it),
     }
 }
+
+pub(crate) fn ty_recover(_db: &impl HirDatabase, _cycle: &[String], _def: &TyDefId) -> Ty {
+    Ty::Unknown
+}
+
 pub(crate) fn value_ty_query(db: &impl HirDatabase, def: ValueTyDefId) -> Ty {
     match def {
         ValueTyDefId::FunctionId(it) => type_for_fn(db, it),
@@ -743,17 +757,24 @@ pub(crate) fn value_ty_query(db: &impl HirDatabase, def: ValueTyDefId) -> Ty {
     }
 }
 
-pub(crate) fn impl_ty_query(db: &impl HirDatabase, impl_id: ImplId) -> ImplTy {
+pub(crate) fn impl_self_ty_query(db: &impl HirDatabase, impl_id: ImplId) -> Ty {
     let impl_data = db.impl_data(impl_id);
     let resolver = impl_id.resolver(db);
-    let self_ty = Ty::from_hir(db, &resolver, &impl_data.target_type);
-    match impl_data.target_trait.as_ref() {
-        Some(trait_ref) => {
-            match TraitRef::from_hir(db, &resolver, trait_ref, Some(self_ty.clone())) {
-                Some(it) => ImplTy::TraitRef(it),
-                None => ImplTy::Inherent(self_ty),
-            }
-        }
-        None => ImplTy::Inherent(self_ty),
-    }
+    Ty::from_hir(db, &resolver, &impl_data.target_type)
+}
+
+pub(crate) fn impl_self_ty_recover(
+    _db: &impl HirDatabase,
+    _cycle: &[String],
+    _impl_id: &ImplId,
+) -> Ty {
+    Ty::Unknown
+}
+
+pub(crate) fn impl_trait_query(db: &impl HirDatabase, impl_id: ImplId) -> Option<TraitRef> {
+    let impl_data = db.impl_data(impl_id);
+    let resolver = impl_id.resolver(db);
+    let self_ty = db.impl_self_ty(impl_id);
+    let target_trait = impl_data.target_trait.as_ref()?;
+    TraitRef::from_hir(db, &resolver, target_trait, Some(self_ty.clone()))
 }
diff --git a/crates/ra_hir_ty/src/method_resolution.rs b/crates/ra_hir_ty/src/method_resolution.rs
index ee1936b0e..2bded3dbd 100644
--- a/crates/ra_hir_ty/src/method_resolution.rs
+++ b/crates/ra_hir_ty/src/method_resolution.rs
@@ -19,7 +19,7 @@ use crate::{
     db::HirDatabase,
     primitive::{FloatBitness, Uncertain},
     utils::all_super_traits,
-    Canonical, ImplTy, InEnvironment, TraitEnvironment, TraitRef, Ty, TypeCtor,
+    Canonical, InEnvironment, TraitEnvironment, TraitRef, Ty, TypeCtor,
 };
 
 /// This is used as a key for indexing impls.
@@ -58,11 +58,12 @@ impl CrateImplBlocks {
         let crate_def_map = db.crate_def_map(krate);
         for (_module_id, module_data) in crate_def_map.modules.iter() {
             for &impl_id in module_data.impls.iter() {
-                match db.impl_ty(impl_id) {
-                    ImplTy::TraitRef(tr) => {
+                match db.impl_trait(impl_id) {
+                    Some(tr) => {
                         res.impls_by_trait.entry(tr.trait_).or_default().push(impl_id);
                     }
-                    ImplTy::Inherent(self_ty) => {
+                    None => {
+                        let self_ty = db.impl_self_ty(impl_id);
                         if let Some(self_ty_fp) = TyFingerprint::for_impl(&self_ty) {
                             res.impls.entry(self_ty_fp).or_default().push(impl_id);
                         }
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
index 3766ab981..a3cc5cf95 100644
--- a/crates/ra_hir_ty/src/tests.rs
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -222,6 +222,56 @@ mod collections {
 }
 
 #[test]
+fn infer_ranges() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+fn test() {
+    let a = ..;
+    let b = 1..;
+    let c = ..2u32;
+    let d = 1..2usize;
+    let e = ..=10;
+    let f = 'a'..='z';
+
+    let t = (a, b, c, d, e, f);
+    t<|>;
+}
+
+//- /std.rs crate:std
+#[prelude_import] use prelude::*;
+mod prelude {}
+
+pub mod ops {
+    pub struct Range<Idx> {
+        pub start: Idx,
+        pub end: Idx,
+    }
+    pub struct RangeFrom<Idx> {
+        pub start: Idx,
+    }
+    struct RangeFull;
+    pub struct RangeInclusive<Idx> {
+        start: Idx,
+        end: Idx,
+        is_empty: u8,
+    }
+    pub struct RangeTo<Idx> {
+        pub end: Idx,
+    }
+    pub struct RangeToInclusive<Idx> {
+        pub end: Idx,
+    }
+}
+"#,
+    );
+    assert_eq!(
+        "(RangeFull, RangeFrom<i32>, RangeTo<u32>, Range<usize>, RangeToInclusive<i32>, RangeInclusive<char>)",
+        type_at_pos(&db, pos),
+    );
+}
+
+#[test]
 fn infer_while_let() {
     let (db, pos) = TestDB::with_position(
         r#"
@@ -2104,7 +2154,6 @@ fn test(x: Foo, y: Bar<&str>, z: Baz<i8, u8>) {
 }
 
 #[test]
-#[should_panic] // we currently can't handle this
 fn recursive_type_alias() {
     assert_snapshot!(
         infer(r#"
@@ -2113,7 +2162,10 @@ type Foo = Foo;
 type Bar = A<Bar>;
 fn test(x: Foo) {}
 "#),
-        @""
+        @r###"
+    [59; 60) 'x': {unknown}
+    [67; 69) '{}': ()
+    "###
     )
 }
 
@@ -4662,10 +4714,48 @@ fn test<T, U>() where T::Item: Trait2, T: Trait<U::Item>, U: Trait<()> {
 }
 
 #[test]
-// FIXME this is currently a Salsa panic; it would be nicer if it just returned
-// in Unknown, and we should be able to do that once Salsa allows us to handle
-// the cycle. But at least it doesn't overflow for now.
-#[should_panic]
+fn trait_impl_self_ty() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait<T> {
+   fn foo(&self);
+}
+
+struct S;
+
+impl Trait<Self> for S {}
+
+fn test() {
+    S.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "()");
+}
+
+#[test]
+fn trait_impl_self_ty_cycle() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait {
+   fn foo(&self);
+}
+
+struct S<T>;
+
+impl Trait for S<Self> {}
+
+fn test() {
+    S.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
 fn unselected_projection_in_trait_env_cycle_1() {
     let t = type_at(
         r#"
@@ -4686,10 +4776,6 @@ fn test<T: Trait>() where T: Trait2<T::Item> {
 }
 
 #[test]
-// FIXME this is currently a Salsa panic; it would be nicer if it just returned
-// in Unknown, and we should be able to do that once Salsa allows us to handle
-// the cycle. But at least it doesn't overflow for now.
-#[should_panic]
 fn unselected_projection_in_trait_env_cycle_2() {
     let t = type_at(
         r#"
diff --git a/crates/ra_hir_ty/src/traits/chalk.rs b/crates/ra_hir_ty/src/traits/chalk.rs
index 35de37e6b..104346ada 100644
--- a/crates/ra_hir_ty/src/traits/chalk.rs
+++ b/crates/ra_hir_ty/src/traits/chalk.rs
@@ -20,8 +20,8 @@ use ra_db::salsa::{InternId, InternKey};
 
 use super::{AssocTyValue, Canonical, ChalkContext, Impl, Obligation};
 use crate::{
-    db::HirDatabase, display::HirDisplay, ApplicationTy, GenericPredicate, ImplTy, ProjectionTy,
-    Substs, TraitRef, Ty, TypeCtor, TypeWalk,
+    db::HirDatabase, display::HirDisplay, ApplicationTy, GenericPredicate, ProjectionTy, Substs,
+    TraitRef, Ty, TypeCtor, TypeWalk,
 };
 
 /// This represents a trait whose name we could not resolve.
@@ -630,10 +630,7 @@ fn impl_block_datum(
     chalk_id: chalk_ir::ImplId,
     impl_id: ImplId,
 ) -> Option<Arc<ImplDatum<ChalkIr>>> {
-    let trait_ref = match db.impl_ty(impl_id) {
-        ImplTy::TraitRef(it) => it,
-        ImplTy::Inherent(_) => return None,
-    };
+    let trait_ref = db.impl_trait(impl_id)?;
     let impl_data = db.impl_data(impl_id);
 
     let generic_params = db.generic_params(impl_id.into());
@@ -787,11 +784,7 @@ fn type_alias_associated_ty_value(
         _ => panic!("assoc ty value should be in impl"),
     };
 
-    let trait_ref = match db.impl_ty(impl_id) {
-        ImplTy::TraitRef(it) => it,
-        // we don't return any assoc ty values if the impl'd trait can't be resolved
-        ImplTy::Inherent(_) => panic!("assoc ty value should not exist"),
-    };
+    let trait_ref = db.impl_trait(impl_id).expect("assoc ty value should not exist"); // we don't return any assoc ty values if the impl'd trait can't be resolved
 
     let assoc_ty = db
         .trait_data(trait_ref.trait_)
diff --git a/crates/ra_ide/src/references/rename.rs b/crates/ra_ide/src/references/rename.rs
index ea6b354c2..b804d5f6d 100644
--- a/crates/ra_ide/src/references/rename.rs
+++ b/crates/ra_ide/src/references/rename.rs
@@ -2,7 +2,7 @@
 
 use hir::ModuleSource;
 use ra_db::{RelativePath, RelativePathBuf, SourceDatabase, SourceDatabaseExt};
-use ra_syntax::{algo::find_node_at_offset, ast, AstNode, SyntaxNode};
+use ra_syntax::{algo::find_node_at_offset, ast, tokenize, AstNode, SyntaxKind, SyntaxNode};
 use ra_text_edit::TextEdit;
 
 use crate::{
@@ -17,6 +17,13 @@ pub(crate) fn rename(
     position: FilePosition,
     new_name: &str,
 ) -> Option<RangeInfo<SourceChange>> {
+    let tokens = tokenize(new_name);
+    if tokens.len() != 1
+        || (tokens[0].kind != SyntaxKind::IDENT && tokens[0].kind != SyntaxKind::UNDERSCORE)
+    {
+        return None;
+    }
+
     let parse = db.parse(position.file_id);
     if let Some((ast_name, ast_module)) =
         find_name_and_module_at_offset(parse.tree().syntax(), position)
@@ -124,6 +131,49 @@ mod tests {
     };
 
     #[test]
+    fn test_rename_to_underscore() {
+        test_rename(
+            r#"
+    fn main() {
+        let i<|> = 1;
+    }"#,
+            "_",
+            r#"
+    fn main() {
+        let _ = 1;
+    }"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_to_raw_identifier() {
+        test_rename(
+            r#"
+    fn main() {
+        let i<|> = 1;
+    }"#,
+            "r#fn",
+            r#"
+    fn main() {
+        let r#fn = 1;
+    }"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_to_invalid_identifier() {
+        let (analysis, position) = single_file_with_position(
+            "
+    fn main() {
+        let i<|> = 1;
+    }",
+        );
+        let new_name = "invalid!";
+        let source_change = analysis.rename(position, new_name).unwrap();
+        assert!(source_change.is_none());
+    }
+
+    #[test]
     fn test_rename_for_local() {
         test_rename(
             r#"
diff --git a/crates/ra_lsp_server/Cargo.toml b/crates/ra_lsp_server/Cargo.toml
index 21aef842c..41672eaff 100644
--- a/crates/ra_lsp_server/Cargo.toml
+++ b/crates/ra_lsp_server/Cargo.toml
@@ -13,7 +13,6 @@ relative-path = "1.0.0"
 serde_json = "1.0.34"
 serde = { version = "1.0.83", features = ["derive"] }
 crossbeam-channel = "0.4"
-flexi_logger = "0.14.0"
 log = "0.4.3"
 lsp-types = { version = "0.61.0", features = ["proposed"] }
 rustc-hash = "1.0"
@@ -27,6 +26,7 @@ lsp-server = "0.3.0"
 ra_project_model = { path = "../ra_project_model" }
 ra_prof = { path = "../ra_prof" }
 ra_vfs_glob = { path = "../ra_vfs_glob" }
+env_logger = { version = "0.7.1", default-features = false, features = ["humantime"] }
 
 [dev-dependencies]
 tempfile = "3"
diff --git a/crates/ra_lsp_server/src/main.rs b/crates/ra_lsp_server/src/main.rs
index e13c8ca14..8076a7fa5 100644
--- a/crates/ra_lsp_server/src/main.rs
+++ b/crates/ra_lsp_server/src/main.rs
@@ -1,6 +1,5 @@
 //! `ra_lsp_server` binary
 
-use flexi_logger::{Duplicate, Logger};
 use lsp_server::Connection;
 use ra_lsp_server::{show_message, Result, ServerConfig};
 use ra_prof;
@@ -14,11 +13,7 @@ fn main() -> Result<()> {
 fn setup_logging() -> Result<()> {
     std::env::set_var("RUST_BACKTRACE", "short");
 
-    let logger = Logger::with_env_or_str("error").duplicate_to_stderr(Duplicate::All);
-    match std::env::var("RA_LOG_DIR") {
-        Ok(ref v) if v == "1" => logger.log_to_file().directory("log").start()?,
-        _ => logger.start()?,
-    };
+    env_logger::try_init()?;
 
     ra_prof::set_filter(match std::env::var("RA_PROFILE") {
         Ok(spec) => ra_prof::Filter::from_spec(&spec),
diff --git a/crates/ra_lsp_server/src/main_loop/handlers.rs b/crates/ra_lsp_server/src/main_loop/handlers.rs
index c81fa7f67..ca47ff5e1 100644
--- a/crates/ra_lsp_server/src/main_loop/handlers.rs
+++ b/crates/ra_lsp_server/src/main_loop/handlers.rs
@@ -480,8 +480,6 @@ pub fn handle_prepare_rename(
     let _p = profile("handle_prepare_rename");
     let position = params.try_conv_with(&world)?;
 
-    // We support renaming references like handle_rename does.
-    // In the future we may want to reject the renaming of things like keywords here too.
     let optional_change = world.analysis().rename(position, "dummy")?;
     let range = match optional_change {
         None => return Ok(None),
diff --git a/crates/ra_lsp_server/tests/heavy_tests/main.rs b/crates/ra_lsp_server/tests/heavy_tests/main.rs
index 2ba82ab05..29224cbe8 100644
--- a/crates/ra_lsp_server/tests/heavy_tests/main.rs
+++ b/crates/ra_lsp_server/tests/heavy_tests/main.rs
@@ -15,7 +15,6 @@ use tempfile::TempDir;
 
 use crate::support::{project, Project};
 
-const LOG: &'static str = "";
 const PROFILE: &'static str = "";
 // const PROFILE: &'static str = "*@3>100";
 
diff --git a/crates/ra_lsp_server/tests/heavy_tests/support.rs b/crates/ra_lsp_server/tests/heavy_tests/support.rs
index 86073b57d..d5ea52fa9 100644
--- a/crates/ra_lsp_server/tests/heavy_tests/support.rs
+++ b/crates/ra_lsp_server/tests/heavy_tests/support.rs
@@ -7,7 +7,6 @@ use std::{
 };
 
 use crossbeam_channel::{after, select, Receiver};
-use flexi_logger::Logger;
 use lsp_server::{Connection, Message, Notification, Request};
 use lsp_types::{
     notification::{DidOpenTextDocument, Exit},
@@ -53,7 +52,7 @@ impl<'a> Project<'a> {
         let tmp_dir = self.tmp_dir.unwrap_or_else(|| TempDir::new().unwrap());
         static INIT: Once = Once::new();
         INIT.call_once(|| {
-            let _ = Logger::with_env_or_str(crate::LOG).start().unwrap();
+            let _ = env_logger::builder().is_test(true).try_init().unwrap();
             ra_prof::set_filter(if crate::PROFILE.is_empty() {
                 ra_prof::Filter::disabled()
             } else {
diff --git a/docs/dev/README.md b/docs/dev/README.md
index 0f64d7e5f..2f6215d6b 100644
--- a/docs/dev/README.md
+++ b/docs/dev/README.md
@@ -124,9 +124,8 @@ Logging is done by both rust-analyzer and VS Code, so it might be tricky to
 figure out where logs go.
 
 Inside rust-analyzer, we use the standard `log` crate for logging, and
-`flexi_logger` for logging frotend. By default, log goes to stderr (the same as
-with `env_logger`), but the stderr itself is processed by VS Code. To mirror
-logs to a `./log` directory, set `RA_LOG_DIR=1` environmental variable.
+`env_logger` for logging frontend. By default, log goes to stderr, but the
+stderr itself is processed by VS Code.
 
 To see stderr in the running VS Code instance, go to the "Output" tab of the
 panel and select `rust-analyzer`. This shows `eprintln!` as well. Note that