diff --git a/Cargo.lock b/Cargo.lock
index 0154b96751d36..f6334e9bdb815 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -29,7 +29,7 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "html5ever 0.22.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "maplit 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "matches 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "tendril 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -170,13 +170,12 @@ dependencies = [
  "cmake 0.1.38 (registry+https://github.com/rust-lang/crates.io-index)",
  "filetime 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "getopts 0.2.19 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "petgraph 0.4.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "pretty_assertions 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "time 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -192,7 +191,6 @@ name = "build-manifest"
 version = "0.1.0"
 dependencies = [
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -266,7 +264,7 @@ dependencies = [
  "ignore 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "im-rc 12.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "jobserver 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazycell 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "libgit2-sys 0.7.11 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -374,7 +372,7 @@ dependencies = [
  "clippy_lints 0.0.212",
  "compiletest_rs 0.3.22 (registry+https://github.com/rust-lang/crates.io-index)",
  "derive-new 0.5.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-workspace-hack 1.0.0",
  "rustc_tools_util 0.1.1",
@@ -394,7 +392,7 @@ dependencies = [
  "cargo_metadata 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "if_chain 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "matches 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "pulldown-cmark 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "quine-mc_cluskey 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -465,14 +463,13 @@ dependencies = [
  "env_logger 0.5.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "filetime 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "getopts 0.2.19 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "miow 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustfix 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -592,7 +589,7 @@ dependencies = [
  "arrayvec 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "crossbeam-utils 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "memoffset 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "nodrop 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)",
  "scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -606,7 +603,7 @@ dependencies = [
  "arrayvec 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "crossbeam-utils 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "memoffset 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -751,7 +748,7 @@ name = "elasticlunr-rs"
 version = "2.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1032,7 +1029,7 @@ name = "handlebars"
 version = "0.32.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "pest 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "pest_derive 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1047,7 +1044,7 @@ name = "handlebars"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "pest 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "pest_derive 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1143,7 +1140,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crossbeam-channel 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "globset 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "memchr 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1169,7 +1166,7 @@ dependencies = [
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "error-chain 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "flate2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "tar 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1265,7 +1262,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "lazy_static"
-version = "1.2.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -1354,7 +1351,7 @@ name = "log_settings"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1441,7 +1438,7 @@ dependencies = [
  "error-chain 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "handlebars 0.32.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.7.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "memchr 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "open 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1469,7 +1466,7 @@ dependencies = [
  "error-chain 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "handlebars 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.7.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "memchr 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "open 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1703,7 +1700,7 @@ dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "openssl-sys 0.9.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1971,7 +1968,7 @@ dependencies = [
  "bit-set 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "quick-error 1.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2045,7 +2042,7 @@ dependencies = [
  "derive_more 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "env_logger 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "humantime 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rls-span 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-ap-syntax 407.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2141,7 +2138,7 @@ version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crossbeam-deque 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2243,7 +2240,7 @@ dependencies = [
  "home 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "jsonrpc-core 10.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "lsp-codec 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "lsp-types 0.57.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2349,7 +2346,7 @@ dependencies = [
  "fmt_macros 0.0.0",
  "graphviz 0.0.0",
  "jobserver 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "measureme 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2402,7 +2399,7 @@ dependencies = [
  "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "ena 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "jobserver 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-ap-graphviz 407.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2532,7 +2529,7 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crossbeam-deque 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -2543,7 +2540,7 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crossbeam-deque 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -2702,7 +2699,7 @@ dependencies = [
  "ena 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "graphviz 0.0.0",
  "jobserver 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3097,7 +3094,7 @@ dependencies = [
  "getopts 0.2.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "ignore 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-ap-rustc_target 407.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3143,7 +3140,7 @@ name = "schannel"
 version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -3313,7 +3310,7 @@ name = "string_cache"
 version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "new_debug_unreachable 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "phf_shared 0.7.22 (registry+https://github.com/rust-lang/crates.io-index)",
  "precomputed-hash 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3404,7 +3401,7 @@ name = "syntax"
 version = "0.0.0"
 dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_data_structures 0.0.0",
  "rustc_errors 0.0.0",
@@ -3549,7 +3546,7 @@ name = "thread_local"
 version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -3558,7 +3555,6 @@ version = "0.1.0"
 dependencies = [
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.33 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -3664,7 +3660,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crossbeam-utils 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.21 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "mio 0.6.16 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3783,7 +3779,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "error-chain 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "is-match 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -3795,7 +3791,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "error-chain 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "is-match 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -4160,7 +4156,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum jsonrpc-core 10.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7a5152c3fda235dfd68341b3edf4121bc4428642c93acbd6de88c26bf95fc5d7"
 "checksum kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
 "checksum lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "76f033c7ad61445c5b347c7382dd1237847eb1bce590fe50365dcb33d546be73"
-"checksum lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a374c89b9db55895453a74c1e38861d9deec0b01b405a82516e9d5de4820dea1"
+"checksum lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bc5729f27f159ddd61f4df6228e827e86643d4d3e7c32183cb30a1c08f604a14"
 "checksum lazycell 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b294d6fa9ee409a054354afc4352b0b9ef7ca222c69b8812cbea9e7d2bf3783f"
 "checksum libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)" = "c6785aa7dd976f5fbf3b71cfd9cd49d7f783c1ff565a858d71031c6c313aa5c6"
 "checksum libgit2-sys 0.7.11 (registry+https://github.com/rust-lang/crates.io-index)" = "48441cb35dc255da8ae72825689a95368bf510659ae1ad55dc4aa88cb1789bf1"
diff --git a/src/bootstrap/Cargo.toml b/src/bootstrap/Cargo.toml
index 3151b56d8e84e..589ee9276a5a3 100644
--- a/src/bootstrap/Cargo.toml
+++ b/src/bootstrap/Cargo.toml
@@ -42,11 +42,10 @@ num_cpus = "1.0"
 getopts = "0.2.19"
 cc = "1.0.35"
 libc = "0.2"
-serde = "1.0.8"
-serde_derive = "1.0.8"
+serde = { version = "1.0.8", features = ["derive"] }
 serde_json = "1.0.2"
 toml = "0.4"
-lazy_static = "0.2"
+lazy_static = "1.3.0"
 time = "0.1"
 petgraph = "0.4.13"
 
diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index c84eb6476e087..51663e9316982 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -11,6 +11,8 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::time::{Duration, Instant};
 
+use build_helper::t;
+
 use crate::cache::{Cache, Interned, INTERNER};
 use crate::check;
 use crate::compile;
@@ -1308,6 +1310,8 @@ mod __test {
     use crate::config::Config;
     use std::thread;
 
+    use pretty_assertions::assert_eq;
+
     fn configure(host: &[&str], target: &[&str]) -> Config {
         let mut config = Config::default_opts();
         // don't save toolstates
diff --git a/src/bootstrap/cache.rs b/src/bootstrap/cache.rs
index 239959682cb00..f137a7b8cc281 100644
--- a/src/bootstrap/cache.rs
+++ b/src/bootstrap/cache.rs
@@ -13,6 +13,8 @@ use std::path::{Path, PathBuf};
 use std::sync::Mutex;
 use std::cmp::{PartialOrd, Ord, Ordering};
 
+use lazy_static::lazy_static;
+
 use crate::builder::Step;
 
 pub struct Interned<T>(usize, PhantomData<*const T>);
diff --git a/src/bootstrap/clean.rs b/src/bootstrap/clean.rs
index b52e1a7b0e681..73be8bfed8e88 100644
--- a/src/bootstrap/clean.rs
+++ b/src/bootstrap/clean.rs
@@ -9,6 +9,8 @@ use std::fs;
 use std::io::{self, ErrorKind};
 use std::path::Path;
 
+use build_helper::t;
+
 use crate::Build;
 
 pub fn clean(build: &Build, all: bool) {
diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 66443d472d334..9c4e856f0b88b 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -15,8 +15,9 @@ use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio, exit};
 use std::str;
 
-use build_helper::{output, mtime, up_to_date};
+use build_helper::{output, mtime, t, up_to_date};
 use filetime::FileTime;
+use serde::Deserialize;
 use serde_json;
 
 use crate::dist;
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 0c31c41ceda86..b1d009a674066 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -10,8 +10,10 @@ use std::path::{Path, PathBuf};
 use std::process;
 use std::cmp;
 
+use build_helper::t;
 use num_cpus;
 use toml;
+use serde::Deserialize;
 use crate::cache::{INTERNER, Interned};
 use crate::flags::Flags;
 pub use crate::flags::Subcommand;
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 57c06061c34ae..b0616ff66918c 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -14,7 +14,7 @@ use std::io::Write;
 use std::path::{PathBuf, Path};
 use std::process::{Command, Stdio};
 
-use build_helper::output;
+use build_helper::{output, t};
 
 use crate::{Compiler, Mode, LLVM_TOOLS};
 use crate::channel;
diff --git a/src/bootstrap/doc.rs b/src/bootstrap/doc.rs
index 330f66c1df0df..9c3a17bff6b7a 100644
--- a/src/bootstrap/doc.rs
+++ b/src/bootstrap/doc.rs
@@ -13,7 +13,7 @@ use std::io;
 use std::path::{PathBuf, Path};
 
 use crate::Mode;
-use build_helper::up_to_date;
+use build_helper::{t, up_to_date};
 
 use crate::util::symlink_dir;
 use crate::builder::{Builder, Compiler, RunConfig, ShouldRun, Step};
diff --git a/src/bootstrap/install.rs b/src/bootstrap/install.rs
index 2d040d60e5fd7..deda30b6bbd9b 100644
--- a/src/bootstrap/install.rs
+++ b/src/bootstrap/install.rs
@@ -8,6 +8,8 @@ use std::fs;
 use std::path::{Path, PathBuf, Component};
 use std::process::Command;
 
+use build_helper::t;
+
 use crate::dist::{self, pkgname, sanitize_sh, tmpdir};
 
 use crate::builder::{Builder, RunConfig, ShouldRun, Step};
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index f63aac0f0e249..ca4489655ca7b 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -108,17 +108,6 @@
 #![feature(core_intrinsics)]
 #![feature(drain_filter)]
 
-#[macro_use]
-extern crate build_helper;
-#[macro_use]
-extern crate serde_derive;
-#[macro_use]
-extern crate lazy_static;
-
-#[cfg(test)]
-#[macro_use]
-extern crate pretty_assertions;
-
 use std::cell::{RefCell, Cell};
 use std::collections::{HashSet, HashMap};
 use std::env;
@@ -134,7 +123,9 @@ use std::os::unix::fs::symlink as symlink_file;
 #[cfg(windows)]
 use std::os::windows::fs::symlink_file;
 
-use build_helper::{run_silent, run_suppressed, try_run_silent, try_run_suppressed, output, mtime};
+use build_helper::{
+    mtime, output, run_silent, run_suppressed, t, try_run_silent, try_run_suppressed,
+};
 use filetime::FileTime;
 
 use crate::util::{exe, libdir, OutputFolder, CiEnv};
diff --git a/src/bootstrap/metadata.rs b/src/bootstrap/metadata.rs
index 7fa377f310b4f..4a71fd2ce0bd2 100644
--- a/src/bootstrap/metadata.rs
+++ b/src/bootstrap/metadata.rs
@@ -4,6 +4,7 @@ use std::path::PathBuf;
 use std::collections::HashSet;
 
 use build_helper::output;
+use serde::Deserialize;
 use serde_json;
 
 use crate::{Build, Crate};
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index 285f9458c44b6..5777331b9bfd5 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -14,7 +14,7 @@ use std::fs::{self, File};
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
-use build_helper::output;
+use build_helper::{output, t};
 use cmake;
 use cc;
 
diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index fa6857cdc1125..dc65fb9b79706 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -15,7 +15,7 @@ use std::fs;
 use std::path::PathBuf;
 use std::process::Command;
 
-use build_helper::output;
+use build_helper::{output, t};
 
 use crate::Build;
 
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 38027aded9c53..a3d96836aad54 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -11,7 +11,7 @@ use std::iter;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
-use build_helper::{self, output};
+use build_helper::{self, output, t};
 
 use crate::builder::{Builder, Compiler, Kind, RunConfig, ShouldRun, Step};
 use crate::cache::{Interned, INTERNER};
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index c23ddbdbc6810..edcd68d010e84 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -4,6 +4,8 @@ use std::path::PathBuf;
 use std::process::{Command, exit};
 use std::collections::HashSet;
 
+use build_helper::t;
+
 use crate::Mode;
 use crate::Compiler;
 use crate::builder::{Step, RunConfig, ShouldRun, Builder};
diff --git a/src/bootstrap/toolstate.rs b/src/bootstrap/toolstate.rs
index 8ff7c09fc2996..e86209be91fe1 100644
--- a/src/bootstrap/toolstate.rs
+++ b/src/bootstrap/toolstate.rs
@@ -1,3 +1,5 @@
+use serde::{Deserialize, Serialize};
+
 #[derive(Copy, Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
 #[serde(rename_all = "kebab-case")]
 /// Whether a tool can be compiled, tested or neither
diff --git a/src/bootstrap/util.rs b/src/bootstrap/util.rs
index bda1e56e1e73b..a162c65672f82 100644
--- a/src/bootstrap/util.rs
+++ b/src/bootstrap/util.rs
@@ -11,6 +11,8 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::time::{SystemTime, Instant};
 
+use build_helper::t;
+
 use crate::config::Config;
 use crate::builder::Builder;
 
diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 848e9ca58e595..4d5707560b048 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -50,7 +50,6 @@ use errors::Applicability;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc_data_structures::thin_vec::ThinVec;
-use rustc_data_structures::sync::Lrc;
 
 use std::collections::{BTreeSet, BTreeMap};
 use std::mem;
@@ -59,10 +58,10 @@ use syntax::attr;
 use syntax::ast;
 use syntax::ast::*;
 use syntax::errors;
-use syntax::ext::hygiene::{Mark, SyntaxContext};
+use syntax::ext::hygiene::Mark;
 use syntax::print::pprust;
 use syntax::ptr::P;
-use syntax::source_map::{self, respan, CompilerDesugaringKind, Spanned};
+use syntax::source_map::{respan, CompilerDesugaringKind, Spanned};
 use syntax::std_inject;
 use syntax::symbol::{keywords, Symbol};
 use syntax::tokenstream::{TokenStream, TokenTree};
@@ -854,27 +853,6 @@ impl<'a> LoweringContext<'a> {
         Ident::with_empty_ctxt(Symbol::gensym(s))
     }
 
-    /// Reuses the span but adds information like the kind of the desugaring and features that are
-    /// allowed inside this span.
-    fn mark_span_with_reason(
-        &self,
-        reason: CompilerDesugaringKind,
-        span: Span,
-        allow_internal_unstable: Option<Lrc<[Symbol]>>,
-    ) -> Span {
-        let mark = Mark::fresh(Mark::root());
-        mark.set_expn_info(source_map::ExpnInfo {
-            call_site: span,
-            def_site: Some(span),
-            format: source_map::CompilerDesugaring(reason),
-            allow_internal_unstable,
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            edition: source_map::hygiene::default_edition(),
-        });
-        span.with_ctxt(SyntaxContext::empty().apply_mark(mark))
-    }
-
     fn with_anonymous_lifetime_mode<R>(
         &mut self,
         anonymous_lifetime_mode: AnonymousLifetimeMode,
@@ -1162,7 +1140,7 @@ impl<'a> LoweringContext<'a> {
             attrs: ThinVec::new(),
         };
 
-        let unstable_span = self.mark_span_with_reason(
+        let unstable_span = self.sess.source_map().mark_span_with_reason(
             CompilerDesugaringKind::Async,
             span,
             Some(vec![
@@ -1569,7 +1547,7 @@ impl<'a> LoweringContext<'a> {
         // desugaring that explicitly states that we don't want to track that.
         // Not tracking it makes lints in rustc and clippy very fragile as
         // frequently opened issues show.
-        let exist_ty_span = self.mark_span_with_reason(
+        let exist_ty_span = self.sess.source_map().mark_span_with_reason(
             CompilerDesugaringKind::ExistentialReturnType,
             span,
             None,
@@ -2443,7 +2421,7 @@ impl<'a> LoweringContext<'a> {
     ) -> hir::FunctionRetTy {
         let span = output.span();
 
-        let exist_ty_span = self.mark_span_with_reason(
+        let exist_ty_span = self.sess.source_map().mark_span_with_reason(
             CompilerDesugaringKind::Async,
             span,
             None,
@@ -4179,7 +4157,7 @@ impl<'a> LoweringContext<'a> {
             }),
             ExprKind::TryBlock(ref body) => {
                 self.with_catch_scope(body.id, |this| {
-                    let unstable_span = this.mark_span_with_reason(
+                    let unstable_span = this.sess.source_map().mark_span_with_reason(
                         CompilerDesugaringKind::TryBlock,
                         body.span,
                         Some(vec![
@@ -4612,7 +4590,7 @@ impl<'a> LoweringContext<'a> {
                 // expand <head>
                 let mut head = self.lower_expr(head);
                 let head_sp = head.span;
-                let desugared_span = self.mark_span_with_reason(
+                let desugared_span = self.sess.source_map().mark_span_with_reason(
                     CompilerDesugaringKind::ForLoop,
                     head_sp,
                     None,
@@ -4773,7 +4751,7 @@ impl<'a> LoweringContext<'a> {
                 //                 return Try::from_error(From::from(err)),
                 // }
 
-                let unstable_span = self.mark_span_with_reason(
+                let unstable_span = self.sess.source_map().mark_span_with_reason(
                     CompilerDesugaringKind::QuestionMark,
                     e.span,
                     Some(vec![
@@ -4781,7 +4759,7 @@ impl<'a> LoweringContext<'a> {
                     ].into()),
                 );
                 let try_span = self.sess.source_map().end_point(e.span);
-                let try_span = self.mark_span_with_reason(
+                let try_span = self.sess.source_map().mark_span_with_reason(
                     CompilerDesugaringKind::QuestionMark,
                     try_span,
                     Some(vec![
@@ -5566,12 +5544,12 @@ impl<'a> LoweringContext<'a> {
             );
             self.sess.abort_if_errors();
         }
-        let span = self.mark_span_with_reason(
+        let span = self.sess.source_map().mark_span_with_reason(
             CompilerDesugaringKind::Await,
             await_span,
             None,
         );
-        let gen_future_span = self.mark_span_with_reason(
+        let gen_future_span = self.sess.source_map().mark_span_with_reason(
             CompilerDesugaringKind::Await,
             await_span,
             Some(vec![Symbol::intern("gen_future")].into()),
diff --git a/src/librustc_mir/util/elaborate_drops.rs b/src/librustc_mir/util/elaborate_drops.rs
index 856783bcbaa46..98ca7c32675c8 100644
--- a/src/librustc_mir/util/elaborate_drops.rs
+++ b/src/librustc_mir/util/elaborate_drops.rs
@@ -10,7 +10,7 @@ use rustc::ty::util::IntTypeExt;
 use rustc_data_structures::indexed_vec::Idx;
 use crate::util::patch::MirPatch;
 
-use std::u32;
+use std::convert::TryInto;
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum DropFlagState {
@@ -545,10 +545,9 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
         self.elaborator.patch().new_block(result)
     }
 
-    /// create a loop that drops an array:
-    ///
-
+    /// Create a loop that drops an array:
     ///
+    /// ```text
     /// loop-block:
     ///    can_go = cur == length_or_end
     ///    if can_go then succ else drop-block
@@ -561,15 +560,16 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
     ///        cur = cur + 1
     ///    }
     ///    drop(ptr)
-    fn drop_loop(&mut self,
-                 succ: BasicBlock,
-                 cur: Local,
-                 length_or_end: &Place<'tcx>,
-                 ety: Ty<'tcx>,
-                 unwind: Unwind,
-                 ptr_based: bool)
-                 -> BasicBlock
-    {
+    /// ```
+    fn drop_loop(
+        &mut self,
+        succ: BasicBlock,
+        cur: Local,
+        length_or_end: &Place<'tcx>,
+        ety: Ty<'tcx>,
+        unwind: Unwind,
+        ptr_based: bool,
+    ) -> BasicBlock {
         let copy = |place: &Place<'tcx>| Operand::Copy(place.clone());
         let move_ = |place: &Place<'tcx>| Operand::Move(place.clone());
         let tcx = self.tcx();
@@ -591,13 +591,13 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
                     elem: ProjectionElem::Deref,
                 }))
              ),
-             Rvalue::BinaryOp(BinOp::Offset, copy(&Place::Base(PlaceBase::Local(cur))), one))
+             Rvalue::BinaryOp(BinOp::Offset, move_(&Place::Base(PlaceBase::Local(cur))), one))
         } else {
             (Rvalue::Ref(
                  tcx.lifetimes.re_erased,
                  BorrowKind::Mut { allow_two_phase_borrow: false },
                  self.place.clone().index(cur)),
-             Rvalue::BinaryOp(BinOp::Add, copy(&Place::Base(PlaceBase::Local(cur))), one))
+             Rvalue::BinaryOp(BinOp::Add, move_(&Place::Base(PlaceBase::Local(cur))), one))
         };
 
         let drop_block = BasicBlockData {
@@ -647,9 +647,9 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
         // }
 
         if let Some(size) = opt_size {
-            assert!(size <= (u32::MAX as u64),
-                    "move out check doesn't implemented for array bigger then u32");
-            let size = size as u32;
+            let size: u32 = size.try_into().unwrap_or_else(|_| {
+                bug!("move out check isn't implemented for array sizes bigger than u32::MAX");
+            });
             let fields: Vec<(Place<'tcx>, Option<D::Path>)> = (0..size).map(|i| {
                 (self.place.clone().elem(ProjectionElem::ConstantIndex{
                     offset: i,
@@ -667,33 +667,42 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
 
         let move_ = |place: &Place<'tcx>| Operand::Move(place.clone());
         let tcx = self.tcx();
-        let size = &Place::Base(PlaceBase::Local(self.new_temp(tcx.types.usize)));
-        let size_is_zero = &Place::Base(PlaceBase::Local(self.new_temp(tcx.types.bool)));
+        let elem_size = &Place::Base(PlaceBase::Local(self.new_temp(tcx.types.usize)));
+        let len = &Place::Base(PlaceBase::Local(self.new_temp(tcx.types.usize)));
+
+        static USIZE_SWITCH_ZERO: &[u128] = &[0];
+
         let base_block = BasicBlockData {
             statements: vec![
-                self.assign(size, Rvalue::NullaryOp(NullOp::SizeOf, ety)),
-                self.assign(size_is_zero, Rvalue::BinaryOp(BinOp::Eq,
-                                                           move_(size),
-                                                           self.constant_usize(0)))
+                self.assign(elem_size, Rvalue::NullaryOp(NullOp::SizeOf, ety)),
+                self.assign(len, Rvalue::Len(self.place.clone())),
             ],
             is_cleanup: self.unwind.is_cleanup(),
             terminator: Some(Terminator {
                 source_info: self.source_info,
-                kind: TerminatorKind::if_(
-                    tcx,
-                    move_(size_is_zero),
-                    self.drop_loop_pair(ety, false),
-                    self.drop_loop_pair(ety, true)
-                )
+                kind: TerminatorKind::SwitchInt {
+                    discr: move_(elem_size),
+                    switch_ty: tcx.types.usize,
+                    values: From::from(USIZE_SWITCH_ZERO),
+                    targets: vec![
+                        self.drop_loop_pair(ety, false, len.clone()),
+                        self.drop_loop_pair(ety, true, len.clone()),
+                    ],
+                },
             })
         };
         self.elaborator.patch().new_block(base_block)
     }
 
-    // create a pair of drop-loops of `place`, which drops its contents
-    // even in the case of 1 panic. If `ptr_based`, create a pointer loop,
-    // otherwise create an index loop.
-    fn drop_loop_pair(&mut self, ety: Ty<'tcx>, ptr_based: bool) -> BasicBlock {
+    /// Ceates a pair of drop-loops of `place`, which drops its contents, even
+    /// in the case of 1 panic. If `ptr_based`, creates a pointer loop,
+    /// otherwise create an index loop.
+    fn drop_loop_pair(
+        &mut self,
+        ety: Ty<'tcx>,
+        ptr_based: bool,
+        length: Place<'tcx>,
+    ) -> BasicBlock {
         debug!("drop_loop_pair({:?}, {:?})", ety, ptr_based);
         let tcx = self.tcx();
         let iter_ty = if ptr_based {
@@ -703,7 +712,6 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
         };
 
         let cur = self.new_temp(iter_ty);
-        let length = Place::Base(PlaceBase::Local(self.new_temp(tcx.types.usize)));
         let length_or_end = if ptr_based {
             // FIXME check if we want to make it return a `Place` directly
             // if all use sites want a `Place::Base` anyway.
@@ -722,9 +730,8 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
                            ptr_based)
         });
 
-        let succ = self.succ; // FIXME(#43234)
         let loop_block = self.drop_loop(
-            succ,
+            self.succ,
             cur,
             &length_or_end,
             ety,
@@ -732,31 +739,32 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
             ptr_based);
 
         let cur = Place::Base(PlaceBase::Local(cur));
-        let zero = self.constant_usize(0);
-        let mut drop_block_stmts = vec![];
-        drop_block_stmts.push(self.assign(&length, Rvalue::Len(self.place.clone())));
-        if ptr_based {
+        let drop_block_stmts = if ptr_based {
             let tmp_ty = tcx.mk_mut_ptr(self.place_ty(self.place));
             let tmp = Place::Base(PlaceBase::Local(self.new_temp(tmp_ty)));
             // tmp = &mut P;
             // cur = tmp as *mut T;
             // end = Offset(cur, len);
-            drop_block_stmts.push(self.assign(&tmp, Rvalue::Ref(
-                tcx.lifetimes.re_erased,
-                BorrowKind::Mut { allow_two_phase_borrow: false },
-                self.place.clone()
-            )));
-            drop_block_stmts.push(self.assign(&cur, Rvalue::Cast(
-                CastKind::Misc, Operand::Move(tmp), iter_ty
-            )));
-            drop_block_stmts.push(self.assign(&length_or_end,
-                Rvalue::BinaryOp(BinOp::Offset,
-                     Operand::Copy(cur), Operand::Move(length)
-            )));
+            vec![
+                self.assign(&tmp, Rvalue::Ref(
+                    tcx.lifetimes.re_erased,
+                    BorrowKind::Mut { allow_two_phase_borrow: false },
+                    self.place.clone()
+                )),
+                self.assign(
+                    &cur,
+                    Rvalue::Cast(CastKind::Misc, Operand::Move(tmp), iter_ty),
+                ),
+                self.assign(
+                    &length_or_end,
+                    Rvalue::BinaryOp(BinOp::Offset, Operand::Copy(cur), Operand::Move(length)
+                )),
+            ]
         } else {
-            // index = 0 (length already pushed)
-            drop_block_stmts.push(self.assign(&cur, Rvalue::Use(zero)));
-        }
+            // cur = 0 (length already pushed)
+            let zero = self.constant_usize(0);
+            vec![self.assign(&cur, Rvalue::Use(zero))]
+        };
         let drop_block = self.elaborator.patch().new_block(BasicBlockData {
             statements: drop_block_stmts,
             is_cleanup: unwind.is_cleanup(),
@@ -768,7 +776,7 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
 
         // FIXME(#34708): handle partially-dropped array/slice elements.
         let reset_block = self.drop_flag_reset_block(DropFlagMode::Deep, drop_block, unwind);
-        self.drop_flag_test_block(reset_block, succ, unwind)
+        self.drop_flag_test_block(reset_block, self.succ, unwind)
     }
 
     /// The slow-path - create an "open", elaborated drop for a type
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 64c8ff8ff8630..965f52be31cde 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4168,9 +4168,25 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                 oprnd_t = self.make_overloaded_place_return_type(method).ty;
                                 self.write_method_call(expr.hir_id, method);
                             } else {
-                                type_error_struct!(tcx.sess, expr.span, oprnd_t, E0614,
-                                                   "type `{}` cannot be dereferenced",
-                                                   oprnd_t).emit();
+                                let mut err = type_error_struct!(
+                                    tcx.sess,
+                                    expr.span,
+                                    oprnd_t,
+                                    E0614,
+                                    "type `{}` cannot be dereferenced",
+                                    oprnd_t,
+                                );
+                                let sp = tcx.sess.source_map().start_point(expr.span);
+                                if let Some(sp) = tcx.sess.parse_sess.ambiguous_block_expr_parse
+                                    .borrow().get(&sp)
+                                {
+                                    tcx.sess.parse_sess.expr_parentheses_needed(
+                                        &mut err,
+                                        *sp,
+                                        None,
+                                    );
+                                }
+                                err.emit();
                                 oprnd_t = tcx.types.err;
                             }
                         }
diff --git a/src/libstd/io/cursor.rs b/src/libstd/io/cursor.rs
index f627fb0f562f0..a94176e710005 100644
--- a/src/libstd/io/cursor.rs
+++ b/src/libstd/io/cursor.rs
@@ -72,7 +72,7 @@ use core::convert::TryInto;
 /// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Default)]
 pub struct Cursor<T> {
     inner: T,
     pos: u64,
diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index 9eba76cc04a64..03aebeda47c48 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -357,29 +357,6 @@ macro_rules! dbg {
     };
 }
 
-/// Awaits the completion of an async call.
-#[macro_export]
-#[unstable(feature = "await_macro", issue = "50547")]
-#[allow_internal_unstable(gen_future, generators)]
-#[allow_internal_unsafe]
-macro_rules! r#await {
-    ($e:expr) => { {
-        let mut pinned = $e;
-        loop {
-            if let $crate::task::Poll::Ready(x) =
-                $crate::future::poll_with_tls_context(unsafe {
-                    $crate::pin::Pin::new_unchecked(&mut pinned)
-                })
-            {
-                break x;
-            }
-            // FIXME(cramertj) prior to stabilizing await, we have to ensure that this
-            // can't be used to create a generator on stable via `|| await!()`.
-            yield
-        }
-    } }
-}
-
 /// Selects the first successful receive event from a number of receivers.
 ///
 /// This macro is used to wait for the first event to occur on a number of
diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index ab5823eaca52a..084a69f4cda0f 100644
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -554,7 +554,10 @@ fn inner_parse_loop<'root, 'tt>(
             match item.top_elts.get_tt(idx) {
                 // Need to descend into a sequence
                 TokenTree::Sequence(sp, seq) => {
-                    // Examine the case where there are 0 matches of this sequence
+                    // Examine the case where there are 0 matches of this sequence. We are
+                    // implicitly disallowing OneOrMore from having 0 matches here. Thus, that will
+                    // result in a "no rules expected token" error by virtue of this matcher not
+                    // working.
                     if seq.op == quoted::KleeneOp::ZeroOrMore
                         || seq.op == quoted::KleeneOp::ZeroOrOne
                     {
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index b1b9d25b3d56b..a53cc2fe66173 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -151,7 +151,7 @@ fn generic_extension<'cx>(cx: &'cx mut ExtCtxt<'_>,
 
                 let rhs_spans = rhs.iter().map(|t| t.span()).collect::<Vec<_>>();
                 // rhs has holes ( `$id` and `$(...)` that need filled)
-                let mut tts = transcribe(cx, Some(named_matches), rhs);
+                let mut tts = transcribe(cx, &named_matches, rhs);
 
                 // Replace all the tokens for the corresponding positions in the macro, to maintain
                 // proper positions in error reporting, while maintaining the macro_backtrace.
diff --git a/src/libsyntax/ext/tt/quoted.rs b/src/libsyntax/ext/tt/quoted.rs
index b24edb57e527e..ed8395f11ad50 100644
--- a/src/libsyntax/ext/tt/quoted.rs
+++ b/src/libsyntax/ext/tt/quoted.rs
@@ -73,6 +73,7 @@ pub enum KleeneOp {
     ZeroOrMore,
     /// Kleene plus (`+`) for one or more repetitions
     OneOrMore,
+    /// Kleene optional (`?`) for zero or one reptitions
     ZeroOrOne,
 }
 
diff --git a/src/libsyntax/ext/tt/transcribe.rs b/src/libsyntax/ext/tt/transcribe.rs
index bd2adb5ac13ba..0cefcf1ce034b 100644
--- a/src/libsyntax/ext/tt/transcribe.rs
+++ b/src/libsyntax/ext/tt/transcribe.rs
@@ -1,10 +1,10 @@
 use crate::ast::Ident;
 use crate::ext::base::ExtCtxt;
 use crate::ext::expand::Marker;
-use crate::ext::tt::macro_parser::{NamedMatch, MatchedSeq, MatchedNonterminal};
+use crate::ext::tt::macro_parser::{MatchedNonterminal, MatchedSeq, NamedMatch};
 use crate::ext::tt::quoted;
 use crate::mut_visit::noop_visit_tt;
-use crate::parse::token::{self, Token, NtTT};
+use crate::parse::token::{self, NtTT, Token};
 use crate::tokenstream::{DelimSpan, TokenStream, TokenTree, TreeAndJoint};
 
 use smallvec::{smallvec, SmallVec};
@@ -13,24 +13,16 @@ use syntax_pos::DUMMY_SP;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
 use std::mem;
-use std::ops::Add;
 use std::rc::Rc;
 
-// An iterator over the token trees in a delimited token tree (`{ ... }`) or a sequence (`$(...)`).
+/// An iterator over the token trees in a delimited token tree (`{ ... }`) or a sequence (`$(...)`).
 enum Frame {
-    Delimited {
-        forest: Lrc<quoted::Delimited>,
-        idx: usize,
-        span: DelimSpan,
-    },
-    Sequence {
-        forest: Lrc<quoted::SequenceRepetition>,
-        idx: usize,
-        sep: Option<Token>,
-    },
+    Delimited { forest: Lrc<quoted::Delimited>, idx: usize, span: DelimSpan },
+    Sequence { forest: Lrc<quoted::SequenceRepetition>, idx: usize, sep: Option<Token> },
 }
 
 impl Frame {
+    /// Construct a new frame around the delimited set of tokens.
     fn new(tts: Vec<quoted::TokenTree>) -> Frame {
         let forest = Lrc::new(quoted::Delimited { delim: token::NoDelim, tts: tts });
         Frame::Delimited { forest: forest, idx: 0, span: DelimSpan::dummy() }
@@ -54,84 +46,161 @@ impl Iterator for Frame {
     }
 }
 
-/// This can do Macro-By-Example transcription. On the other hand, if
-/// `src` contains no `TokenTree::{Sequence, MetaVar, MetaVarDecl}`s, `interp` can
-/// (and should) be None.
-pub fn transcribe(cx: &ExtCtxt<'_>,
-                  interp: Option<FxHashMap<Ident, Rc<NamedMatch>>>,
-                  src: Vec<quoted::TokenTree>)
-                  -> TokenStream {
+/// This can do Macro-By-Example transcription.
+/// - `interp` is a map of meta-variables to the tokens (non-terminals) they matched in the
+///   invocation. We are assuming we already know there is a match.
+/// - `src` is the RHS of the MBE, that is, the "example" we are filling in.
+///
+/// For example,
+///
+/// ```rust
+/// macro_rules! foo {
+///     ($id:ident) => { println!("{}", stringify!($id)); }
+/// }
+///
+/// foo!(bar);
+/// ```
+///
+/// `interp` would contain `$id => bar` and `src` would contain `println!("{}", stringify!($id));`.
+///
+/// `transcribe` would return a `TokenStream` containing `println!("{}", stringify!(bar));`.
+///
+/// Along the way, we do some additional error checking.
+pub fn transcribe(
+    cx: &ExtCtxt<'_>,
+    interp: &FxHashMap<Ident, Rc<NamedMatch>>,
+    src: Vec<quoted::TokenTree>,
+) -> TokenStream {
+    // Nothing for us to transcribe...
+    if src.is_empty() {
+        return TokenStream::empty();
+    }
+
+    // We descend into the RHS (`src`), expanding things as we go. This stack contains the things
+    // we have yet to expand/are still expanding. We start the stack off with the whole RHS.
     let mut stack: SmallVec<[Frame; 1]> = smallvec![Frame::new(src)];
-    let interpolations = interp.unwrap_or_else(FxHashMap::default); /* just a convenience */
+
+    // As we descend in the RHS, we will need to be able to match nested sequences of matchers.
+    // `repeats` keeps track of where we are in matching at each level, with the last element being
+    // the most deeply nested sequence. This is used as a stack.
     let mut repeats = Vec::new();
+
+    // `result` contains resulting token stream from the TokenTree we just finished processing. At
+    // the end, this will contain the full result of transcription, but at arbitrary points during
+    // `transcribe`, `result` will contain subsets of the final result.
+    //
+    // Specifically, as we descend into each TokenTree, we will push the existing results onto the
+    // `result_stack` and clear `results`. We will then produce the results of transcribing the
+    // TokenTree into `results`. Then, as we unwind back out of the `TokenTree`, we will pop the
+    // `result_stack` and append `results` too it to produce the new `results` up to that point.
+    //
+    // Thus, if we try to pop the `result_stack` and it is empty, we have reached the top-level
+    // again, and we are done transcribing.
     let mut result: Vec<TreeAndJoint> = Vec::new();
     let mut result_stack = Vec::new();
 
     loop {
+        // Look at the last frame on the stack.
         let tree = if let Some(tree) = stack.last_mut().unwrap().next() {
+            // If it still has a TokenTree we have not looked at yet, use that tree.
             tree
-        } else {
+        }
+        // The else-case never produces a value for `tree` (it `continue`s or `return`s).
+        else {
+            // Otherwise, if we have just reached the end of a sequence and we can keep repeating,
+            // go back to the beginning of the sequence.
             if let Frame::Sequence { ref mut idx, ref sep, .. } = *stack.last_mut().unwrap() {
                 let (ref mut repeat_idx, repeat_len) = *repeats.last_mut().unwrap();
                 *repeat_idx += 1;
                 if *repeat_idx < repeat_len {
                     *idx = 0;
                     if let Some(sep) = sep.clone() {
-                        // repeat same span, I guess
                         let prev_span = match result.last() {
                             Some((tt, _)) => tt.span(),
                             None => DUMMY_SP,
                         };
                         result.push(TokenTree::Token(prev_span, sep).into());
                     }
-                    continue
+                    continue;
                 }
             }
 
+            // We are done with the top of the stack. Pop it. Depending on what it was, we do
+            // different things. Note that the outermost item must be the delimited, wrapped RHS
+            // that was passed in originally to `transcribe`.
             match stack.pop().unwrap() {
+                // Done with a sequence. Pop from repeats.
                 Frame::Sequence { .. } => {
                     repeats.pop();
                 }
+
+                // We are done processing a Delimited. If this is the top-level delimited, we are
+                // done. Otherwise, we unwind the result_stack to append what we have produced to
+                // any previous results.
                 Frame::Delimited { forest, span, .. } => {
                     if result_stack.is_empty() {
+                        // No results left to compute! We are back at the top-level.
                         return TokenStream::new(result);
                     }
-                    let tree = TokenTree::Delimited(
-                        span,
-                        forest.delim,
-                        TokenStream::new(result).into(),
-                    );
+
+                    // Step back into the parent Delimited.
+                    let tree =
+                        TokenTree::Delimited(span, forest.delim, TokenStream::new(result).into());
                     result = result_stack.pop().unwrap();
                     result.push(tree.into());
                 }
             }
-            continue
+            continue;
         };
 
+        // At this point, we know we are in the middle of a TokenTree (the last one on `stack`).
+        // `tree` contains the next `TokenTree` to be processed.
         match tree {
-            quoted::TokenTree::Sequence(sp, seq) => {
-                // FIXME(pcwalton): Bad copy.
-                match lockstep_iter_size(&quoted::TokenTree::Sequence(sp, seq.clone()),
-                                         &interpolations,
-                                         &repeats) {
+            // We are descending into a sequence. We first make sure that the matchers in the RHS
+            // and the matches in `interp` have the same shape. Otherwise, either the caller or the
+            // macro writer has made a mistake.
+            seq @ quoted::TokenTree::Sequence(..) => {
+                match lockstep_iter_size(&seq, interp, &repeats) {
                     LockstepIterSize::Unconstrained => {
-                        cx.span_fatal(sp.entire(), /* blame macro writer */
-                            "attempted to repeat an expression \
-                             containing no syntax \
-                             variables matched as repeating at this depth");
+                        cx.span_fatal(
+                            seq.span(), /* blame macro writer */
+                            "attempted to repeat an expression containing no syntax variables \
+                             matched as repeating at this depth",
+                        );
                     }
+
                     LockstepIterSize::Contradiction(ref msg) => {
+                        // FIXME: this should be impossible. I (mark-i-m) believe it would
+                        // represent a bug in the macro_parser.
                         // FIXME #2887 blame macro invoker instead
-                        cx.span_fatal(sp.entire(), &msg[..]);
+                        cx.span_fatal(seq.span(), &msg[..]);
                     }
+
                     LockstepIterSize::Constraint(len, _) => {
+                        // We do this to avoid an extra clone above. We know that this is a
+                        // sequence already.
+                        let (sp, seq) = if let quoted::TokenTree::Sequence(sp, seq) = seq {
+                            (sp, seq)
+                        } else {
+                            unreachable!()
+                        };
+
+                        // Is the repetition empty?
                         if len == 0 {
                             if seq.op == quoted::KleeneOp::OneOrMore {
+                                // FIXME: this should be impossible because we check for this in
+                                // macro_parser.rs
                                 // FIXME #2887 blame invoker
                                 cx.span_fatal(sp.entire(), "this must repeat at least once");
                             }
                         } else {
+                            // 0 is the initial counter (we have done 0 repretitions so far). `len`
+                            //   is the total number of reptitions we should generate.
                             repeats.push((0, len));
+
+                            // The first time we encounter the sequence we push it to the stack. It
+                            // then gets reused (see the beginning of the loop) until we are done
+                            // repeating.
                             stack.push(Frame::Sequence {
                                 idx: 0,
                                 sep: seq.separator.clone(),
@@ -141,10 +210,16 @@ pub fn transcribe(cx: &ExtCtxt<'_>,
                     }
                 }
             }
-            // FIXME #2887: think about span stuff here
+
+            // Replace the meta-var with the matched token tree from the invocation.
             quoted::TokenTree::MetaVar(mut sp, ident) => {
-                if let Some(cur_matched) = lookup_cur_matched(ident, &interpolations, &repeats) {
+                // Find the matched nonterminal from the macro invocation, and use it to replace
+                // the meta-var.
+                if let Some(cur_matched) = lookup_cur_matched(ident, interp, &repeats) {
                     if let MatchedNonterminal(ref nt) = *cur_matched {
+                        // FIXME #2887: why do we apply a mark when matching a token tree meta-var
+                        // (e.g. `$x:tt`), but not when we are matching any other type of token
+                        // tree?
                         if let NtTT(ref tt) = **nt {
                             result.push(tt.clone().into());
                         } else {
@@ -153,10 +228,15 @@ pub fn transcribe(cx: &ExtCtxt<'_>,
                             result.push(token.into());
                         }
                     } else {
-                        cx.span_fatal(sp, /* blame the macro writer */
-                            &format!("variable '{}' is still repeating at this depth", ident));
+                        // We were unable to descend far enough. This is an error.
+                        cx.span_fatal(
+                            sp, /* blame the macro writer */
+                            &format!("variable '{}' is still repeating at this depth", ident),
+                        );
                     }
                 } else {
+                    // If we aren't able to match the meta-var, we push it back into the result but
+                    // with modified syntax context. (I believe this supports nested macros).
                     let ident =
                         Ident::new(ident.name, ident.span.apply_mark(cx.current_expansion.mark));
                     sp = sp.apply_mark(cx.current_expansion.mark);
@@ -164,26 +244,44 @@ pub fn transcribe(cx: &ExtCtxt<'_>,
                     result.push(TokenTree::Token(sp, token::Token::from_ast_ident(ident)).into());
                 }
             }
+
+            // If we are entering a new delimiter, we push its contents to the `stack` to be
+            // processed, and we push all of the currently produced results to the `result_stack`.
+            // We will produce all of the results of the inside of the `Delimited` and then we will
+            // jump back out of the Delimited, pop the result_stack and add the new results back to
+            // the previous results (from outside the Delimited).
             quoted::TokenTree::Delimited(mut span, delimited) => {
                 span = span.apply_mark(cx.current_expansion.mark);
                 stack.push(Frame::Delimited { forest: delimited, idx: 0, span: span });
                 result_stack.push(mem::replace(&mut result, Vec::new()));
             }
+
+            // Nothing much to do here. Just push the token to the result, being careful to
+            // preserve syntax context.
             quoted::TokenTree::Token(sp, tok) => {
                 let mut marker = Marker(cx.current_expansion.mark);
                 let mut tt = TokenTree::Token(sp, tok);
                 noop_visit_tt(&mut tt, &mut marker);
                 result.push(tt.into());
             }
+
+            // There should be no meta-var declarations in the invocation of a macro.
             quoted::TokenTree::MetaVarDecl(..) => panic!("unexpected `TokenTree::MetaVarDecl"),
         }
     }
 }
 
-fn lookup_cur_matched(ident: Ident,
-                      interpolations: &FxHashMap<Ident, Rc<NamedMatch>>,
-                      repeats: &[(usize, usize)])
-                      -> Option<Rc<NamedMatch>> {
+/// Lookup the meta-var named `ident` and return the matched token tree from the invocation using
+/// the set of matches `interpolations`.
+///
+/// See the definition of `repeats` in the `transcribe` function. `repeats` is used to descend
+/// into the right place in nested matchers. If we attempt to descend too far, the macro writer has
+/// made a mistake, and we return `None`.
+fn lookup_cur_matched(
+    ident: Ident,
+    interpolations: &FxHashMap<Ident, Rc<NamedMatch>>,
+    repeats: &[(usize, usize)],
+) -> Option<Rc<NamedMatch>> {
     interpolations.get(&ident).map(|matched| {
         let mut matched = matched.clone();
         for &(idx, _) in repeats {
@@ -198,17 +296,30 @@ fn lookup_cur_matched(ident: Ident,
     })
 }
 
+/// An accumulator over a TokenTree to be used with `fold`. During transcription, we need to make
+/// sure that the size of each sequence and all of its nested sequences are the same as the sizes
+/// of all the matched (nested) sequences in the macro invocation. If they don't match, somebody
+/// has made a mistake (either the macro writer or caller).
 #[derive(Clone)]
 enum LockstepIterSize {
+    /// No constraints on length of matcher. This is true for any TokenTree variants except a
+    /// `MetaVar` with an actual `MatchedSeq` (as opposed to a `MatchedNonterminal`).
     Unconstrained,
+
+    /// A `MetaVar` with an actual `MatchedSeq`. The length of the match and the name of the
+    /// meta-var are returned.
     Constraint(usize, Ident),
+
+    /// Two `Constraint`s on the same sequence had different lengths. This is an error.
     Contradiction(String),
 }
 
-impl Add for LockstepIterSize {
-    type Output = LockstepIterSize;
-
-    fn add(self, other: LockstepIterSize) -> LockstepIterSize {
+impl LockstepIterSize {
+    /// Find incompatibilities in matcher/invocation sizes.
+    /// - `Unconstrained` is compatible with everything.
+    /// - `Contradiction` is incompatible with everything.
+    /// - `Constraint(len)` is only compatible with other constraints of the same length.
+    fn with(self, other: LockstepIterSize) -> LockstepIterSize {
         match self {
             LockstepIterSize::Unconstrained => other,
             LockstepIterSize::Contradiction(_) => self,
@@ -217,9 +328,11 @@ impl Add for LockstepIterSize {
                 LockstepIterSize::Contradiction(_) => other,
                 LockstepIterSize::Constraint(r_len, _) if l_len == r_len => self,
                 LockstepIterSize::Constraint(r_len, r_id) => {
-                    let msg = format!("inconsistent lockstep iteration: \
-                                       '{}' has {} items, but '{}' has {}",
-                                      l_id, l_len, r_id, r_len);
+                    let msg = format!(
+                        "inconsistent lockstep iteration: \
+                         '{}' has {} items, but '{}' has {}",
+                        l_id, l_len, r_id, r_len
+                    );
                     LockstepIterSize::Contradiction(msg)
                 }
             },
@@ -227,30 +340,38 @@ impl Add for LockstepIterSize {
     }
 }
 
-fn lockstep_iter_size(tree: &quoted::TokenTree,
-                      interpolations: &FxHashMap<Ident, Rc<NamedMatch>>,
-                      repeats: &[(usize, usize)])
-                      -> LockstepIterSize {
+/// Given a `tree`, make sure that all sequences have the same length as the matches for the
+/// appropriate meta-vars in `interpolations`.
+///
+/// Note that if `repeats` does not match the exact correct depth of a meta-var,
+/// `lookup_cur_matched` will return `None`, which is why this still works even in the presnece of
+/// multiple nested matcher sequences.
+fn lockstep_iter_size(
+    tree: &quoted::TokenTree,
+    interpolations: &FxHashMap<Ident, Rc<NamedMatch>>,
+    repeats: &[(usize, usize)],
+) -> LockstepIterSize {
     use quoted::TokenTree;
     match *tree {
         TokenTree::Delimited(_, ref delimed) => {
             delimed.tts.iter().fold(LockstepIterSize::Unconstrained, |size, tt| {
-                size + lockstep_iter_size(tt, interpolations, repeats)
+                size.with(lockstep_iter_size(tt, interpolations, repeats))
             })
-        },
+        }
         TokenTree::Sequence(_, ref seq) => {
             seq.tts.iter().fold(LockstepIterSize::Unconstrained, |size, tt| {
-                size + lockstep_iter_size(tt, interpolations, repeats)
+                size.with(lockstep_iter_size(tt, interpolations, repeats))
             })
-        },
-        TokenTree::MetaVar(_, name) | TokenTree::MetaVarDecl(_, name, _) =>
+        }
+        TokenTree::MetaVar(_, name) | TokenTree::MetaVarDecl(_, name, _) => {
             match lookup_cur_matched(name, interpolations, repeats) {
                 Some(matched) => match *matched {
                     MatchedNonterminal(_) => LockstepIterSize::Unconstrained,
                     MatchedSeq(ref ads, _) => LockstepIterSize::Constraint(ads.len(), name),
                 },
-                _ => LockstepIterSize::Unconstrained
-            },
+                _ => LockstepIterSize::Unconstrained,
+            }
+        }
         TokenTree::Token(..) => LockstepIterSize::Unconstrained,
     }
 }
diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index 3c342c2ff26a9..2882acb0e780c 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -1598,7 +1598,7 @@ mod tests {
     use std::io;
     use std::path::PathBuf;
     use syntax_pos::{BytePos, Span, NO_EXPANSION};
-    use rustc_data_structures::fx::FxHashSet;
+    use rustc_data_structures::fx::{FxHashSet, FxHashMap};
     use rustc_data_structures::sync::Lock;
 
     fn mk_sess(sm: Lrc<SourceMap>) -> ParseSess {
@@ -1617,6 +1617,7 @@ mod tests {
             raw_identifier_spans: Lock::new(Vec::new()),
             registered_diagnostics: Lock::new(ErrorMap::new()),
             buffered_lints: Lock::new(vec![]),
+            ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
         }
     }
 
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 8c2fab9ada76e..be44b964ba5a7 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -11,12 +11,12 @@ use crate::tokenstream::{TokenStream, TokenTree};
 use crate::diagnostics::plugin::ErrorMap;
 use crate::print::pprust::token_to_string;
 
-use errors::{FatalError, Level, Handler, ColorConfig, Diagnostic, DiagnosticBuilder};
+use errors::{Applicability, FatalError, Level, Handler, ColorConfig, Diagnostic, DiagnosticBuilder};
 use rustc_data_structures::sync::{Lrc, Lock};
 use syntax_pos::{Span, SourceFile, FileName, MultiSpan};
 use log::debug;
 
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::{FxHashSet, FxHashMap};
 use std::borrow::Cow;
 use std::path::{Path, PathBuf};
 use std::str;
@@ -52,6 +52,10 @@ pub struct ParseSess {
     included_mod_stack: Lock<Vec<PathBuf>>,
     source_map: Lrc<SourceMap>,
     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
+    /// Contains the spans of block expressions that could have been incomplete based on the
+    /// operation token that followed it, but that the parser cannot identify without further
+    /// analysis.
+    pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
 }
 
 impl ParseSess {
@@ -75,6 +79,7 @@ impl ParseSess {
             included_mod_stack: Lock::new(vec![]),
             source_map,
             buffered_lints: Lock::new(vec![]),
+            ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
         }
     }
 
@@ -98,6 +103,24 @@ impl ParseSess {
             });
         });
     }
+
+    /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
+    /// parser to continue parsing the following operation as part of the same expression.
+    pub fn expr_parentheses_needed(
+        &self,
+        err: &mut DiagnosticBuilder<'_>,
+        span: Span,
+        alt_snippet: Option<String>,
+    ) {
+        if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
+            err.span_suggestion(
+                span,
+                "parentheses are required to parse this as an expression",
+                format!("({})", snippet),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
 }
 
 #[derive(Clone)]
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index f3eac71ee7761..d97d1e2f0f4ee 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -50,7 +50,10 @@ use crate::symbol::{Symbol, keywords};
 
 use errors::{Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
 use rustc_target::spec::abi::{self, Abi};
-use syntax_pos::{Span, MultiSpan, BytePos, FileName};
+use syntax_pos::{
+    Span, MultiSpan, BytePos, FileName,
+    hygiene::CompilerDesugaringKind,
+};
 use log::{debug, trace};
 
 use std::borrow::Cow;
@@ -186,6 +189,7 @@ enum PrevTokenKind {
     Interpolated,
     Eof,
     Ident,
+    BitOr,
     Other,
 }
 
@@ -1375,6 +1379,7 @@ impl<'a> Parser<'a> {
             token::DocComment(..) => PrevTokenKind::DocComment,
             token::Comma => PrevTokenKind::Comma,
             token::BinOp(token::Plus) => PrevTokenKind::Plus,
+            token::BinOp(token::Or) => PrevTokenKind::BitOr,
             token::Interpolated(..) => PrevTokenKind::Interpolated,
             token::Eof => PrevTokenKind::Eof,
             token::Ident(..) => PrevTokenKind::Ident,
@@ -2806,6 +2811,12 @@ impl<'a> Parser<'a> {
                             let msg = format!("expected expression, found {}",
                                               self.this_token_descr());
                             let mut err = self.fatal(&msg);
+                            let sp = self.sess.source_map().start_point(self.span);
+                            if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow()
+                                .get(&sp)
+                            {
+                                self.sess.expr_parentheses_needed(&mut err, *sp, None);
+                            }
                             err.span_label(self.span, "expected expression");
                             return Err(err);
                         }
@@ -2845,7 +2856,7 @@ impl<'a> Parser<'a> {
                     "struct literals are not allowed here",
                 );
                 err.multipart_suggestion(
-                    "surround the struct literal with parenthesis",
+                    "surround the struct literal with parentheses",
                     vec![
                         (lo.shrink_to_lo(), "(".to_string()),
                         (expr.span.shrink_to_hi(), ")".to_string()),
@@ -3506,9 +3517,42 @@ impl<'a> Parser<'a> {
             }
         };
 
-        if self.expr_is_complete(&lhs) {
-            // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
-            return Ok(lhs);
+        match (self.expr_is_complete(&lhs), AssocOp::from_token(&self.token)) {
+            (true, None) => {
+                // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
+                return Ok(lhs);
+            }
+            (false, _) => {} // continue parsing the expression
+            // An exhaustive check is done in the following block, but these are checked first
+            // because they *are* ambiguous but also reasonable looking incorrect syntax, so we
+            // want to keep their span info to improve diagnostics in these cases in a later stage.
+            (true, Some(AssocOp::Multiply)) | // `{ 42 } *foo = bar;` or `{ 42 } * 3`
+            (true, Some(AssocOp::Subtract)) | // `{ 42 } -5`
+            (true, Some(AssocOp::Add)) => { // `{ 42 } + 42
+                // These cases are ambiguous and can't be identified in the parser alone
+                let sp = self.sess.source_map().start_point(self.span);
+                self.sess.ambiguous_block_expr_parse.borrow_mut().insert(sp, lhs.span);
+                return Ok(lhs);
+            }
+            (true, Some(ref op)) if !op.can_continue_expr_unambiguously() => {
+                return Ok(lhs);
+            }
+            (true, Some(_)) => {
+                // We've found an expression that would be parsed as a statement, but the next
+                // token implies this should be parsed as an expression.
+                // For example: `if let Some(x) = x { x } else { 0 } / 2`
+                let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &format!(
+                    "expected expression, found `{}`",
+                    pprust::token_to_string(&self.token),
+                ));
+                err.span_label(self.span, "expected expression");
+                self.sess.expr_parentheses_needed(
+                    &mut err,
+                    lhs.span,
+                    Some(pprust::expr_to_string(&lhs),
+                ));
+                err.emit();
+            }
         }
         self.expected_tokens.push(TokenType::Operator);
         while let Some(op) = AssocOp::from_token(&self.token) {
@@ -4819,6 +4863,10 @@ impl<'a> Parser<'a> {
                         );
                         let mut err = self.fatal(&msg);
                         err.span_label(self.span, format!("expected {}", expected));
+                        let sp = self.sess.source_map().start_point(self.span);
+                        if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
+                            self.sess.expr_parentheses_needed(&mut err, *sp, None);
+                        }
                         return Err(err);
                     }
                 }
@@ -8727,6 +8775,10 @@ impl<'a> Parser<'a> {
     /// The arguments of the function are replaced in HIR lowering with the arguments created by
     /// this function and the statements created here are inserted at the top of the closure body.
     fn construct_async_arguments(&mut self, asyncness: &mut Spanned<IsAsync>, decl: &mut FnDecl) {
+        // FIXME(davidtwco): This function should really live in the HIR lowering but because
+        // the types constructed here need to be used in parts of resolve so that the correct
+        // locals are considered upvars, it is currently easier for it to live here in the parser,
+        // where it can be constructed once.
         if let IsAsync::Async { ref mut arguments, .. } = asyncness.node {
             for (index, input) in decl.inputs.iter_mut().enumerate() {
                 let id = ast::DUMMY_NODE_ID;
@@ -8741,6 +8793,15 @@ impl<'a> Parser<'a> {
                 // statement.
                 let (binding_mode, ident, is_simple_pattern) = match input.pat.node {
                     PatKind::Ident(binding_mode @ BindingMode::ByValue(_), ident, _) => {
+                        // Simple patterns like this don't have a generated argument, but they are
+                        // moved into the closure with a statement, so any `mut` bindings on the
+                        // argument will be unused. This binding mode can't be removed, because
+                        // this would affect the input to procedural macros, but they can have
+                        // their span marked as being the result of a compiler desugaring so
+                        // that they aren't linted against.
+                        input.pat.span = self.sess.source_map().mark_span_with_reason(
+                            CompilerDesugaringKind::Async, span, None);
+
                         (binding_mode, ident, true)
                     }
                     _ => (BindingMode::ByValue(Mutability::Mutable), ident, false),
@@ -8810,15 +8871,6 @@ impl<'a> Parser<'a> {
                     })
                 };
 
-                // Remove mutability from arguments. If this is not a simple pattern,
-                // those arguments are replaced by `__argN`, so there is no need to do this.
-                if let PatKind::Ident(BindingMode::ByValue(mutability @ Mutability::Mutable), ..) =
-                    &mut input.pat.node
-                {
-                    assert!(is_simple_pattern);
-                    *mutability = Mutability::Immutable;
-                }
-
                 let move_stmt = Stmt { id, node: StmtKind::Local(P(move_local)), span };
                 arguments.push(AsyncArgument { ident, arg, pat_stmt, move_stmt });
             }
diff --git a/src/libsyntax/source_map.rs b/src/libsyntax/source_map.rs
index 08abbf5e8a4dc..215618bd09ca3 100644
--- a/src/libsyntax/source_map.rs
+++ b/src/libsyntax/source_map.rs
@@ -930,6 +930,27 @@ impl SourceMap {
 
         None
     }
+
+    /// Reuses the span but adds information like the kind of the desugaring and features that are
+    /// allowed inside this span.
+    pub fn mark_span_with_reason(
+        &self,
+        reason: hygiene::CompilerDesugaringKind,
+        span: Span,
+        allow_internal_unstable: Option<Lrc<[symbol::Symbol]>>,
+    ) -> Span {
+        let mark = Mark::fresh(Mark::root());
+        mark.set_expn_info(ExpnInfo {
+            call_site: span,
+            def_site: Some(span),
+            format: CompilerDesugaring(reason),
+            allow_internal_unstable,
+            allow_internal_unsafe: false,
+            local_inner_macros: false,
+            edition: hygiene::default_edition(),
+        });
+        span.with_ctxt(SyntaxContext::empty().apply_mark(mark))
+    }
 }
 
 impl SourceMapper for SourceMap {
diff --git a/src/libsyntax/util/parser.rs b/src/libsyntax/util/parser.rs
index 80dabffaba9f4..86e89945afe06 100644
--- a/src/libsyntax/util/parser.rs
+++ b/src/libsyntax/util/parser.rs
@@ -207,6 +207,31 @@ impl AssocOp {
             ObsoleteInPlace | Assign | AssignOp(_) | As | DotDot | DotDotEq | Colon => None
         }
     }
+
+    /// This operator could be used to follow a block unambiguously.
+    ///
+    /// This is used for error recovery at the moment, providing a suggestion to wrap blocks with
+    /// parentheses while having a high degree of confidence on the correctness of the suggestion.
+    pub fn can_continue_expr_unambiguously(&self) -> bool {
+        use AssocOp::*;
+        match self {
+            BitXor | // `{ 42 } ^ 3`
+            Assign | // `{ 42 } = { 42 }`
+            Divide | // `{ 42 } / 42`
+            Modulus | // `{ 42 } % 2`
+            ShiftRight | // `{ 42 } >> 2`
+            LessEqual | // `{ 42 } <= 3`
+            Greater | // `{ 42 } > 3`
+            GreaterEqual | // `{ 42 } >= 3`
+            AssignOp(_) | // `{ 42 } +=`
+            LAnd | // `{ 42 } &&foo`
+            As | // `{ 42 } as usize`
+            // Equal | // `{ 42 } == { 42 }`    Accepting these here would regress incorrect
+            // NotEqual | // `{ 42 } != { 42 }  struct literals parser recovery.
+            Colon => true, // `{ 42 }: usize`
+            _ => false,
+        }
+    }
 }
 
 pub const PREC_RESET: i8 = -100;
diff --git a/src/test/mir-opt/slice-drop-shim.rs b/src/test/mir-opt/slice-drop-shim.rs
new file mode 100644
index 0000000000000..754fad51b21e7
--- /dev/null
+++ b/src/test/mir-opt/slice-drop-shim.rs
@@ -0,0 +1,88 @@
+fn main() {
+    std::ptr::drop_in_place::<[String]> as unsafe fn(_);
+}
+
+// END RUST SOURCE
+
+// START rustc.ptr-real_drop_in_place.[std__string__String].AddMovesForPackedDrops.before.mir
+// let mut _2: usize;
+// let mut _3: usize;
+// let mut _4: usize;
+// let mut _5: &mut std::string::String;
+// let mut _6: bool;
+// let mut _7: &mut std::string::String;
+// let mut _8: bool;
+// let mut _9: *mut std::string::String;
+// let mut _10: *mut std::string::String;
+// let mut _11: &mut std::string::String;
+// let mut _12: bool;
+// let mut _13: &mut std::string::String;
+// let mut _14: bool;
+// let mut _15: *mut [std::string::String];
+// bb0: {
+//     goto -> bb15;
+// }
+// bb1: {
+//     return;
+// }
+// bb2 (cleanup): {
+//     resume;
+// }
+// bb3 (cleanup): {
+//     _5 = &mut (*_1)[_4];
+//     _4 = Add(move _4, const 1usize);
+//     drop((*_5)) -> bb4;
+// }
+// bb4 (cleanup): {
+//     _6 = Eq(_4, _3);
+//     switchInt(move _6) -> [false: bb3, otherwise: bb2];
+// }
+// bb5: {
+//     _7 = &mut (*_1)[_4];
+//     _4 = Add(move _4, const 1usize);
+//     drop((*_7)) -> [return: bb6, unwind: bb4];
+// }
+// bb6: {
+//     _8 = Eq(_4, _3);
+//     switchInt(move _8) -> [false: bb5, otherwise: bb1];
+// }
+// bb7: {
+//     _4 = const 0usize;
+//     goto -> bb6;
+// }
+// bb8: {
+//     goto -> bb7;
+// }
+// bb9 (cleanup): {
+//     _11 = &mut (*_9);
+//     _9 = Offset(move _9, const 1usize);
+//     drop((*_11)) -> bb10;
+// }
+// bb10 (cleanup): {
+//     _12 = Eq(_9, _10);
+//     switchInt(move _12) -> [false: bb9, otherwise: bb2];
+// }
+// bb11: {
+//     _13 = &mut (*_9);
+//     _9 = Offset(move _9, const 1usize);
+//     drop((*_13)) -> [return: bb12, unwind: bb10];
+// }
+// bb12: {
+//     _14 = Eq(_9, _10);
+//     switchInt(move _14) -> [false: bb11, otherwise: bb1];
+// }
+// bb13: {
+//     _15 = &mut (*_1);
+//     _9 = move _15 as *mut std::string::String (Misc);
+//     _10 = Offset(_9, move _3);
+//     goto -> bb12;
+// }
+// bb14: {
+//     goto -> bb13;
+// }
+// bb15: {
+//     _2 = SizeOf(std::string::String);
+//     _3 = Len((*_1));
+//     switchInt(move _2) -> [0usize: bb8, otherwise: bb14];
+// }
+// END rustc.ptr-real_drop_in_place.[std__string__String].AddMovesForPackedDrops.before.mir
diff --git a/src/test/ui/async-await/auxiliary/issue-60674.rs b/src/test/ui/async-await/auxiliary/issue-60674.rs
new file mode 100644
index 0000000000000..680c6e55e5668
--- /dev/null
+++ b/src/test/ui/async-await/auxiliary/issue-60674.rs
@@ -0,0 +1,12 @@
+// force-host
+// no-prefer-dynamic
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn attr(_args: TokenStream, input: TokenStream) -> TokenStream {
+    println!("{}", input);
+    TokenStream::new()
+}
diff --git a/src/test/ui/async-await/issue-60674.rs b/src/test/ui/async-await/issue-60674.rs
new file mode 100644
index 0000000000000..37e356e5baf48
--- /dev/null
+++ b/src/test/ui/async-await/issue-60674.rs
@@ -0,0 +1,14 @@
+// aux-build:issue-60674.rs
+// compile-pass
+// edition:2018
+#![feature(async_await)]
+
+// This is a regression test that ensures that `mut` patterns are not lost when provided as input
+// to a proc macro.
+
+extern crate issue_60674;
+
+#[issue_60674::attr]
+async fn f(mut x: u8) {}
+
+fn main() {}
diff --git a/src/test/ui/async-await/issue-60674.stdout b/src/test/ui/async-await/issue-60674.stdout
new file mode 100644
index 0000000000000..a93944db1c591
--- /dev/null
+++ b/src/test/ui/async-await/issue-60674.stdout
@@ -0,0 +1 @@
+async fn f(mut x: u8) { }
diff --git a/src/test/ui/error-codes/E0423.stderr b/src/test/ui/error-codes/E0423.stderr
index 5cb7121a0d1c3..ec240003f9182 100644
--- a/src/test/ui/error-codes/E0423.stderr
+++ b/src/test/ui/error-codes/E0423.stderr
@@ -3,7 +3,7 @@ error: struct literals are not allowed here
    |
 LL |     if let S { x: _x, y: 2 } = S { x: 1, y: 2 } { println!("Ok"); }
    |                                ^^^^^^^^^^^^^^^^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     if let S { x: _x, y: 2 } = (S { x: 1, y: 2 }) { println!("Ok"); }
    |                                ^                ^
@@ -19,7 +19,7 @@ error: struct literals are not allowed here
    |
 LL |     for _ in std::ops::Range { start: 0, end: 10 } {}
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     for _ in (std::ops::Range { start: 0, end: 10 }) {}
    |              ^                                     ^
diff --git a/src/test/ui/nll/closure-requirements/region-lbr1-does-outlive-lbr2-because-implied-bound.rs b/src/test/ui/nll/closure-requirements/region-lbr1-does-outlive-lbr2-because-implied-bound.rs
index 66290f2ff230a..5a008ad26b444 100644
--- a/src/test/ui/nll/closure-requirements/region-lbr1-does-outlive-lbr2-because-implied-bound.rs
+++ b/src/test/ui/nll/closure-requirements/region-lbr1-does-outlive-lbr2-because-implied-bound.rs
@@ -3,8 +3,7 @@
 
 // compile-flags:-Zborrowck=mir -Zverbose
 // compile-pass
-
-#![allow(warnings)]
+// skip-codegen
 
 fn foo<'a, 'b>(x: &'a &'b u32) -> &'a u32 {
     &**x
diff --git a/src/test/ui/parser/expr-as-stmt.fixed b/src/test/ui/parser/expr-as-stmt.fixed
new file mode 100644
index 0000000000000..1ce6f9c25034f
--- /dev/null
+++ b/src/test/ui/parser/expr-as-stmt.fixed
@@ -0,0 +1,40 @@
+// run-rustfix
+#![allow(unused_variables)]
+#![allow(dead_code)]
+#![allow(unused_must_use)]
+
+fn foo() -> i32 {
+    ({2}) + {2} //~ ERROR expected expression, found `+`
+    //~^ ERROR mismatched types
+}
+
+fn bar() -> i32 {
+    ({2}) + 2 //~ ERROR expected expression, found `+`
+    //~^ ERROR mismatched types
+}
+
+fn zul() -> u32 {
+    let foo = 3;
+    ({ 42 }) + foo; //~ ERROR expected expression, found `+`
+    //~^ ERROR mismatched types
+    32
+}
+
+fn baz() -> i32 {
+    ({ 3 }) * 3 //~ ERROR type `{integer}` cannot be dereferenced
+    //~^ ERROR mismatched types
+}
+
+fn qux(a: Option<u32>, b: Option<u32>) -> bool {
+    (if let Some(x) = a { true } else { false })
+    && //~ ERROR expected expression
+    if let Some(y) = a { true } else { false }
+}
+
+fn moo(x: u32) -> bool {
+    (match x {
+        _ => 1,
+    }) > 0 //~ ERROR expected expression
+}
+
+fn main() {}
diff --git a/src/test/ui/parser/expr-as-stmt.rs b/src/test/ui/parser/expr-as-stmt.rs
new file mode 100644
index 0000000000000..b526c17488eaf
--- /dev/null
+++ b/src/test/ui/parser/expr-as-stmt.rs
@@ -0,0 +1,40 @@
+// run-rustfix
+#![allow(unused_variables)]
+#![allow(dead_code)]
+#![allow(unused_must_use)]
+
+fn foo() -> i32 {
+    {2} + {2} //~ ERROR expected expression, found `+`
+    //~^ ERROR mismatched types
+}
+
+fn bar() -> i32 {
+    {2} + 2 //~ ERROR expected expression, found `+`
+    //~^ ERROR mismatched types
+}
+
+fn zul() -> u32 {
+    let foo = 3;
+    { 42 } + foo; //~ ERROR expected expression, found `+`
+    //~^ ERROR mismatched types
+    32
+}
+
+fn baz() -> i32 {
+    { 3 } * 3 //~ ERROR type `{integer}` cannot be dereferenced
+    //~^ ERROR mismatched types
+}
+
+fn qux(a: Option<u32>, b: Option<u32>) -> bool {
+    if let Some(x) = a { true } else { false }
+    && //~ ERROR expected expression
+    if let Some(y) = a { true } else { false }
+}
+
+fn moo(x: u32) -> bool {
+    match x {
+        _ => 1,
+    } > 0 //~ ERROR expected expression
+}
+
+fn main() {}
diff --git a/src/test/ui/parser/expr-as-stmt.stderr b/src/test/ui/parser/expr-as-stmt.stderr
new file mode 100644
index 0000000000000..a11209998a7d5
--- /dev/null
+++ b/src/test/ui/parser/expr-as-stmt.stderr
@@ -0,0 +1,92 @@
+error: expected expression, found `+`
+  --> $DIR/expr-as-stmt.rs:7:9
+   |
+LL |     {2} + {2}
+   |     --- ^ expected expression
+   |     |
+   |     help: parentheses are required to parse this as an expression: `({2})`
+
+error: expected expression, found `+`
+  --> $DIR/expr-as-stmt.rs:12:9
+   |
+LL |     {2} + 2
+   |     --- ^ expected expression
+   |     |
+   |     help: parentheses are required to parse this as an expression: `({2})`
+
+error: expected expression, found `+`
+  --> $DIR/expr-as-stmt.rs:18:12
+   |
+LL |     { 42 } + foo;
+   |     ------ ^ expected expression
+   |     |
+   |     help: parentheses are required to parse this as an expression: `({ 42 })`
+
+error: expected expression, found `&&`
+  --> $DIR/expr-as-stmt.rs:30:5
+   |
+LL |     if let Some(x) = a { true } else { false }
+   |     ------------------------------------------ help: parentheses are required to parse this as an expression: `(if let Some(x) = a { true } else { false })`
+LL |     &&
+   |     ^^ expected expression
+
+error: expected expression, found `>`
+  --> $DIR/expr-as-stmt.rs:37:7
+   |
+LL |     } > 0
+   |       ^ expected expression
+help: parentheses are required to parse this as an expression
+   |
+LL |     (match x {
+LL |         _ => 1,
+LL |     }) > 0
+   |
+
+error[E0308]: mismatched types
+  --> $DIR/expr-as-stmt.rs:7:6
+   |
+LL |     {2} + {2}
+   |      ^ expected (), found integer
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
+error[E0308]: mismatched types
+  --> $DIR/expr-as-stmt.rs:12:6
+   |
+LL |     {2} + 2
+   |      ^ expected (), found integer
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
+error[E0308]: mismatched types
+  --> $DIR/expr-as-stmt.rs:18:7
+   |
+LL |     { 42 } + foo;
+   |       ^^ expected (), found integer
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
+error[E0308]: mismatched types
+  --> $DIR/expr-as-stmt.rs:24:7
+   |
+LL |     { 3 } * 3
+   |       ^ expected (), found integer
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
+error[E0614]: type `{integer}` cannot be dereferenced
+  --> $DIR/expr-as-stmt.rs:24:11
+   |
+LL |     { 3 } * 3
+   |     ----- ^^^
+   |     |
+   |     help: parentheses are required to parse this as an expression: `({ 3 })`
+
+error: aborting due to 10 previous errors
+
+Some errors have detailed explanations: E0308, E0614.
+For more information about an error, try `rustc --explain E0308`.
diff --git a/src/test/ui/parser/match-arrows-block-then-binop.rs b/src/test/ui/parser/match-arrows-block-then-binop.rs
index 1a40d67492990..56c917c7462f2 100644
--- a/src/test/ui/parser/match-arrows-block-then-binop.rs
+++ b/src/test/ui/parser/match-arrows-block-then-binop.rs
@@ -1,7 +1,7 @@
 fn main() {
-
-    match 0 {
+    let _ = match 0 {
       0 => {
+        0
       } + 5 //~ ERROR expected pattern, found `+`
-    }
+    };
 }
diff --git a/src/test/ui/parser/match-arrows-block-then-binop.stderr b/src/test/ui/parser/match-arrows-block-then-binop.stderr
index a844cac189aa1..bb7df30783acd 100644
--- a/src/test/ui/parser/match-arrows-block-then-binop.stderr
+++ b/src/test/ui/parser/match-arrows-block-then-binop.stderr
@@ -3,6 +3,12 @@ error: expected pattern, found `+`
    |
 LL |       } + 5
    |         ^ expected pattern
+help: parentheses are required to parse this as an expression
+   |
+LL |       0 => ({
+LL |         0
+LL |       }) + 5
+   |
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/parser/struct-literal-in-for.stderr b/src/test/ui/parser/struct-literal-in-for.stderr
index 3c3f6e7f032f6..29af72a5d23d0 100644
--- a/src/test/ui/parser/struct-literal-in-for.stderr
+++ b/src/test/ui/parser/struct-literal-in-for.stderr
@@ -6,7 +6,7 @@ LL |       for x in Foo {
 LL | |         x: 3
 LL | |     }.hi() {
    | |_____^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     for x in (Foo {
 LL |         x: 3
diff --git a/src/test/ui/parser/struct-literal-in-if.stderr b/src/test/ui/parser/struct-literal-in-if.stderr
index 851c495abb4b0..e76c1cb45dd4e 100644
--- a/src/test/ui/parser/struct-literal-in-if.stderr
+++ b/src/test/ui/parser/struct-literal-in-if.stderr
@@ -6,7 +6,7 @@ LL |       if Foo {
 LL | |         x: 3
 LL | |     }.hi() {
    | |_____^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     if (Foo {
 LL |         x: 3
diff --git a/src/test/ui/parser/struct-literal-in-match-discriminant.stderr b/src/test/ui/parser/struct-literal-in-match-discriminant.stderr
index 0058e8981cd25..95b0882b7aeb5 100644
--- a/src/test/ui/parser/struct-literal-in-match-discriminant.stderr
+++ b/src/test/ui/parser/struct-literal-in-match-discriminant.stderr
@@ -6,7 +6,7 @@ LL |       match Foo {
 LL | |         x: 3
 LL | |     } {
    | |_____^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     match (Foo {
 LL |         x: 3
diff --git a/src/test/ui/parser/struct-literal-in-while.stderr b/src/test/ui/parser/struct-literal-in-while.stderr
index 9959a57be8596..acd31b477dc27 100644
--- a/src/test/ui/parser/struct-literal-in-while.stderr
+++ b/src/test/ui/parser/struct-literal-in-while.stderr
@@ -6,7 +6,7 @@ LL |       while Foo {
 LL | |         x: 3
 LL | |     }.hi() {
    | |_____^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     while (Foo {
 LL |         x: 3
diff --git a/src/test/ui/parser/struct-literal-restrictions-in-lamda.stderr b/src/test/ui/parser/struct-literal-restrictions-in-lamda.stderr
index 81f7a91ddb38a..24078074161e6 100644
--- a/src/test/ui/parser/struct-literal-restrictions-in-lamda.stderr
+++ b/src/test/ui/parser/struct-literal-restrictions-in-lamda.stderr
@@ -6,7 +6,7 @@ LL |       while || Foo {
 LL | |         x: 3
 LL | |     }.hi() {
    | |_____^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     while || (Foo {
 LL |         x: 3
diff --git a/src/test/ui/struct-literal-variant-in-if.stderr b/src/test/ui/struct-literal-variant-in-if.stderr
index 55f23baea7aa8..f91b9d7dce60f 100644
--- a/src/test/ui/struct-literal-variant-in-if.stderr
+++ b/src/test/ui/struct-literal-variant-in-if.stderr
@@ -3,7 +3,7 @@ error: struct literals are not allowed here
    |
 LL |     if x == E::I { field1: true, field2: 42 } {}
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     if x == (E::I { field1: true, field2: 42 }) {}
    |             ^                                 ^
@@ -13,7 +13,7 @@ error: struct literals are not allowed here
    |
 LL |     if x == E::V { field: false } {}
    |             ^^^^^^^^^^^^^^^^^^^^^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     if x == (E::V { field: false }) {}
    |             ^                     ^
@@ -23,7 +23,7 @@ error: struct literals are not allowed here
    |
 LL |     if x == E::J { field: -42 } {}
    |             ^^^^^^^^^^^^^^^^^^^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     if x == (E::J { field: -42 }) {}
    |             ^                   ^
@@ -33,7 +33,7 @@ error: struct literals are not allowed here
    |
 LL |     if x == E::K { field: "" } {}
    |             ^^^^^^^^^^^^^^^^^^
-help: surround the struct literal with parenthesis
+help: surround the struct literal with parentheses
    |
 LL |     if x == (E::K { field: "" }) {}
    |             ^                  ^
diff --git a/src/tools/build-manifest/Cargo.toml b/src/tools/build-manifest/Cargo.toml
index 93d0f61e1d9f0..63b6399bb9034 100644
--- a/src/tools/build-manifest/Cargo.toml
+++ b/src/tools/build-manifest/Cargo.toml
@@ -7,4 +7,3 @@ edition = "2018"
 [dependencies]
 toml = "0.4"
 serde = { version = "1.0", features = ["derive"] }
-serde_derive = "1.0"
diff --git a/src/tools/compiletest/Cargo.toml b/src/tools/compiletest/Cargo.toml
index 00e1a53473cda..336d7e32024b7 100644
--- a/src/tools/compiletest/Cargo.toml
+++ b/src/tools/compiletest/Cargo.toml
@@ -11,9 +11,8 @@ filetime = "0.2"
 getopts = "0.2"
 log = "0.4"
 regex = "1.0"
-serde = "1.0"
+serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
-serde_derive = "1.0"
 rustfix = "0.4.1"
 lazy_static = "1.0"
 walkdir = "2"
diff --git a/src/tools/compiletest/src/errors.rs b/src/tools/compiletest/src/errors.rs
index 0329fb0db1422..5b3936ffc1e3b 100644
--- a/src/tools/compiletest/src/errors.rs
+++ b/src/tools/compiletest/src/errors.rs
@@ -7,6 +7,8 @@ use std::io::BufReader;
 use std::path::Path;
 use std::str::FromStr;
 
+use log::*;
+
 #[derive(Clone, Debug, PartialEq)]
 pub enum ErrorKind {
     Help,
diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs
index 54e9b76a21ee0..dbc477585cbfc 100644
--- a/src/tools/compiletest/src/header.rs
+++ b/src/tools/compiletest/src/header.rs
@@ -4,6 +4,8 @@ use std::io::prelude::*;
 use std::io::BufReader;
 use std::path::{Path, PathBuf};
 
+use log::*;
+
 use crate::common::{self, CompareMode, Config, Mode};
 use crate::util;
 
diff --git a/src/tools/compiletest/src/json.rs b/src/tools/compiletest/src/json.rs
index d651b9a92b649..02b09e21ff022 100644
--- a/src/tools/compiletest/src/json.rs
+++ b/src/tools/compiletest/src/json.rs
@@ -3,6 +3,7 @@
 
 use crate::errors::{Error, ErrorKind};
 use crate::runtest::ProcRes;
+use serde::Deserialize;
 use serde_json;
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
diff --git a/src/tools/compiletest/src/main.rs b/src/tools/compiletest/src/main.rs
index dc5d1b9a853ef..e253934e566a7 100644
--- a/src/tools/compiletest/src/main.rs
+++ b/src/tools/compiletest/src/main.rs
@@ -3,14 +3,6 @@
 #![feature(vec_remove_item)]
 #![deny(warnings, rust_2018_idioms)]
 
-#[cfg(unix)]
-extern crate libc;
-#[macro_use]
-extern crate log;
-#[macro_use]
-extern crate lazy_static;
-#[macro_use]
-extern crate serde_derive;
 extern crate test;
 
 use crate::common::CompareMode;
@@ -30,6 +22,7 @@ use crate::util::logv;
 use walkdir::WalkDir;
 use env_logger;
 use getopts;
+use log::*;
 
 use self::header::{EarlyProps, Ignore};
 
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index a11a4f17eb504..3689946c055e5 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -29,6 +29,9 @@ use std::path::{Path, PathBuf};
 use std::process::{Child, Command, ExitStatus, Output, Stdio};
 use std::str;
 
+use lazy_static::lazy_static;
+use log::*;
+
 use crate::extract_gdb_version;
 use crate::is_android_gdb_target;
 
diff --git a/src/tools/compiletest/src/util.rs b/src/tools/compiletest/src/util.rs
index 50dce4b55ae86..adc1224bcd367 100644
--- a/src/tools/compiletest/src/util.rs
+++ b/src/tools/compiletest/src/util.rs
@@ -3,6 +3,8 @@ use std::env;
 use std::path::PathBuf;
 use crate::common::Config;
 
+use log::*;
+
 /// Conversion table from triple OS name to Rust SYSNAME
 const OS_TABLE: &'static [(&'static str, &'static str)] = &[
     ("android", "android"),
diff --git a/src/tools/tidy/Cargo.toml b/src/tools/tidy/Cargo.toml
index 433e9264dd1dc..eeac6cfbb30e0 100644
--- a/src/tools/tidy/Cargo.toml
+++ b/src/tools/tidy/Cargo.toml
@@ -6,6 +6,5 @@ edition = "2018"
 
 [dependencies]
 regex = "1"
-serde = "1.0.8"
-serde_derive = "1.0.8"
+serde = { version = "1.0.8", features = ["derive"] }
 serde_json = "1.0.2"
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index e90737febd5bf..8626ba060bf71 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -5,7 +5,7 @@ use std::fs;
 use std::path::Path;
 use std::process::Command;
 
-use serde_derive::Deserialize;
+use serde::Deserialize;
 use serde_json;
 
 const LICENSES: &[&str] = &[