diff --git a/Cargo.lock b/Cargo.lock
index 873f5da053787..a6dca2048d4e8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -68,7 +68,7 @@ name = "arena"
 version = "0.0.0"
 dependencies = [
  "rustc_data_structures",
- "smallvec",
+ "smallvec 1.0.0",
 ]
 
 [[package]]
@@ -487,7 +487,7 @@ dependencies = [
  "regex-syntax",
  "semver",
  "serde",
- "smallvec",
+ "smallvec 0.6.10",
  "toml",
  "unicode-normalization",
  "url 2.1.0",
@@ -655,7 +655,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0f0ed1a4de2235cabda8558ff5840bffb97fcb64c97827f354a451307df5f72b"
 dependencies = [
  "crossbeam-utils 0.6.5",
- "smallvec",
+ "smallvec 0.6.10",
 ]
 
 [[package]]
@@ -2392,7 +2392,7 @@ dependencies = [
  "libc",
  "rand 0.6.1",
  "rustc_version",
- "smallvec",
+ "smallvec 0.6.10",
  "winapi 0.3.6",
 ]
 
@@ -2407,7 +2407,7 @@ dependencies = [
  "libc",
  "redox_syscall",
  "rustc_version",
- "smallvec",
+ "smallvec 0.6.10",
  "winapi 0.3.6",
 ]
 
@@ -3135,7 +3135,7 @@ dependencies = [
  "rustc_target",
  "scoped-tls",
  "serialize",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax",
  "syntax_pos",
 ]
@@ -3147,7 +3147,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a623fd4805842e9bd0bb6e6dace63efede0ee22de4522a0b03b7c3d15a22f009"
 dependencies = [
  "rustc-ap-rustc_data_structures",
- "smallvec",
+ "smallvec 0.6.10",
 ]
 
 [[package]]
@@ -3176,7 +3176,7 @@ dependencies = [
  "rustc-hash",
  "rustc-rayon 0.2.0",
  "rustc-rayon-core 0.2.0",
- "smallvec",
+ "smallvec 0.6.10",
  "stable_deref_trait",
 ]
 
@@ -3204,7 +3204,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "457a5c204ae2fdaa5bdb5b196e58ca59896870d80445fe423063c9453496e3ea"
 dependencies = [
  "rustc-ap-serialize",
- "smallvec",
+ "smallvec 0.6.10",
 ]
 
 [[package]]
@@ -3250,7 +3250,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "92679240e86f4583cc05f8dcf6439bdab87bac9e6555718469176de9bd52ba20"
 dependencies = [
  "indexmap",
- "smallvec",
+ "smallvec 0.6.10",
 ]
 
 [[package]]
@@ -3270,7 +3270,7 @@ dependencies = [
  "rustc-ap-serialize",
  "rustc-ap-syntax_pos",
  "scoped-tls",
- "smallvec",
+ "smallvec 0.6.10",
 ]
 
 [[package]]
@@ -3393,7 +3393,7 @@ dependencies = [
  "crossbeam-utils 0.6.5",
  "serde",
  "serde_json",
- "smallvec",
+ "smallvec 0.6.10",
  "syn 0.15.35",
  "url 2.1.0",
  "winapi 0.3.6",
@@ -3404,7 +3404,7 @@ name = "rustc_apfloat"
 version = "0.0.0"
 dependencies = [
  "bitflags",
- "smallvec",
+ "smallvec 1.0.0",
 ]
 
 [[package]]
@@ -3484,7 +3484,7 @@ dependencies = [
  "rustc-rayon-core 0.3.0",
  "rustc_index",
  "serialize",
- "smallvec",
+ "smallvec 1.0.0",
  "stable_deref_trait",
 ]
 
@@ -3552,7 +3552,7 @@ name = "rustc_index"
 version = "0.0.0"
 dependencies = [
  "serialize",
- "smallvec",
+ "smallvec 1.0.0",
 ]
 
 [[package]]
@@ -3579,7 +3579,7 @@ dependencies = [
  "rustc_traits",
  "rustc_typeck",
  "serialize",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax",
  "syntax_expand",
  "syntax_ext",
@@ -3650,7 +3650,7 @@ dependencies = [
  "rustc_index",
  "rustc_target",
  "serialize",
- "smallvec",
+ "smallvec 1.0.0",
  "stable_deref_trait",
  "syntax",
  "syntax_expand",
@@ -3675,7 +3675,7 @@ dependencies = [
  "rustc_lexer",
  "rustc_target",
  "serialize",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax",
  "syntax_pos",
 ]
@@ -3746,7 +3746,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_metadata",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax",
  "syntax_expand",
  "syntax_pos",
@@ -3799,7 +3799,7 @@ dependencies = [
  "rustc",
  "rustc_data_structures",
  "rustc_target",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax",
  "syntax_pos",
 ]
@@ -3826,7 +3826,7 @@ dependencies = [
  "rustc_errors",
  "rustc_index",
  "rustc_target",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax",
  "syntax_pos",
 ]
@@ -4070,7 +4070,7 @@ name = "serialize"
 version = "0.0.0"
 dependencies = [
  "indexmap",
- "smallvec",
+ "smallvec 1.0.0",
 ]
 
 [[package]]
@@ -4134,6 +4134,12 @@ version = "0.6.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ab606a9c5e214920bb66c458cd7be8ef094f813f20fe77a54cc7dbfff220d4b7"
 
+[[package]]
+name = "smallvec"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ecf3b85f68e8abaa7555aa5abdb1153079387e60b718283d732f03897fcfc86"
+
 [[package]]
 name = "socket2"
 version = "0.3.8"
@@ -4359,7 +4365,7 @@ dependencies = [
  "rustc_target",
  "scoped-tls",
  "serialize",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax_pos",
 ]
 
@@ -4377,7 +4383,7 @@ dependencies = [
  "rustc_target",
  "scoped-tls",
  "serialize",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax",
  "syntax_pos",
 ]
@@ -4391,7 +4397,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_target",
- "smallvec",
+ "smallvec 1.0.0",
  "syntax",
  "syntax_expand",
  "syntax_pos",
diff --git a/src/libarena/Cargo.toml b/src/libarena/Cargo.toml
index 2643912f6d7d6..5158aab8b7dc5 100644
--- a/src/libarena/Cargo.toml
+++ b/src/libarena/Cargo.toml
@@ -10,4 +10,4 @@ path = "lib.rs"
 
 [dependencies]
 rustc_data_structures = { path = "../librustc_data_structures" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc/Cargo.toml b/src/librustc/Cargo.toml
index de67f46eba643..92b94af75d750 100644
--- a/src/librustc/Cargo.toml
+++ b/src/librustc/Cargo.toml
@@ -39,5 +39,5 @@ parking_lot = "0.9"
 byteorder = { version = "1.3" }
 chalk-engine = { version = "0.9.0", default-features=false }
 rustc_fs_util = { path = "../librustc_fs_util" }
-smallvec = { version = "0.6.8", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 measureme = "0.4"
diff --git a/src/librustc/arena.rs b/src/librustc/arena.rs
index 3daf0fc9df7a0..9b13a910c6174 100644
--- a/src/librustc/arena.rs
+++ b/src/librustc/arena.rs
@@ -304,7 +304,7 @@ impl DropArena {
         // Move the content to the arena by copying it and then forgetting
         // the content of the SmallVec
         vec.as_ptr().copy_to_nonoverlapping(start_ptr, len);
-        mem::forget(vec.drain());
+        mem::forget(vec.drain(..));
 
         // Record the destructors after doing the allocation as that may panic
         // and would cause `object`'s destuctor to run twice if it was recorded before
diff --git a/src/librustc/ty/inhabitedness/def_id_forest.rs b/src/librustc/ty/inhabitedness/def_id_forest.rs
index 63cc60d80aada..227fbf967c0d7 100644
--- a/src/librustc/ty/inhabitedness/def_id_forest.rs
+++ b/src/librustc/ty/inhabitedness/def_id_forest.rs
@@ -76,19 +76,19 @@ impl<'tcx> DefIdForest {
                 break;
             }
 
-            for id in ret.root_ids.drain() {
+            for id in ret.root_ids.drain(..) {
                 if next_forest.contains(tcx, id) {
                     next_ret.push(id);
                 } else {
                     old_ret.push(id);
                 }
             }
-            ret.root_ids.extend(old_ret.drain());
+            ret.root_ids.extend(old_ret.drain(..));
 
             next_ret.extend(next_forest.root_ids.into_iter().filter(|&id| ret.contains(tcx, id)));
 
             mem::swap(&mut next_ret, &mut ret.root_ids);
-            next_ret.drain();
+            next_ret.drain(..);
         }
         ret
     }
@@ -101,7 +101,7 @@ impl<'tcx> DefIdForest {
         let mut ret = DefIdForest::empty();
         let mut next_ret = SmallVec::new();
         for next_forest in iter {
-            next_ret.extend(ret.root_ids.drain().filter(|&id| !next_forest.contains(tcx, id)));
+            next_ret.extend(ret.root_ids.drain(..).filter(|&id| !next_forest.contains(tcx, id)));
 
             for id in next_forest.root_ids {
                 if !next_ret.contains(&id) {
@@ -110,7 +110,7 @@ impl<'tcx> DefIdForest {
             }
 
             mem::swap(&mut next_ret, &mut ret.root_ids);
-            next_ret.drain();
+            next_ret.drain(..);
         }
         ret
     }
diff --git a/src/librustc_apfloat/Cargo.toml b/src/librustc_apfloat/Cargo.toml
index 4fc15f99e484e..726965e1e7180 100644
--- a/src/librustc_apfloat/Cargo.toml
+++ b/src/librustc_apfloat/Cargo.toml
@@ -10,4 +10,4 @@ path = "lib.rs"
 
 [dependencies]
 bitflags = "1.2.1"
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_data_structures/Cargo.toml b/src/librustc_data_structures/Cargo.toml
index 065c8436ae06a..e79b3a81b9654 100644
--- a/src/librustc_data_structures/Cargo.toml
+++ b/src/librustc_data_structures/Cargo.toml
@@ -23,7 +23,7 @@ stable_deref_trait = "1.0.0"
 rayon = { version = "0.3.0", package = "rustc-rayon" }
 rayon-core = { version = "0.3.0", package = "rustc-rayon-core" }
 rustc-hash = "1.0.1"
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc_index = { path = "../librustc_index", package = "rustc_index" }
 
 [dependencies.parking_lot]
diff --git a/src/librustc_index/Cargo.toml b/src/librustc_index/Cargo.toml
index b1ebc95e4881b..1435297f27ada 100644
--- a/src/librustc_index/Cargo.toml
+++ b/src/librustc_index/Cargo.toml
@@ -11,4 +11,4 @@ doctest = false
 
 [dependencies]
 rustc_serialize = { path = "../libserialize", package = "serialize" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_interface/Cargo.toml b/src/librustc_interface/Cargo.toml
index 0d8d765a572c2..98e4f974a9f23 100644
--- a/src/librustc_interface/Cargo.toml
+++ b/src/librustc_interface/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 [dependencies]
 log = "0.4"
 rayon = { version = "0.3.0", package = "rustc-rayon" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
 syntax_ext = { path = "../libsyntax_ext" }
 syntax_expand = { path = "../libsyntax_expand" }
diff --git a/src/librustc_metadata/Cargo.toml b/src/librustc_metadata/Cargo.toml
index 18192e35f8a20..5bc047e001b67 100644
--- a/src/librustc_metadata/Cargo.toml
+++ b/src/librustc_metadata/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 flate2 = "1.0"
 log = "0.4"
 memmap = "0.6"
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
diff --git a/src/librustc_mir/Cargo.toml b/src/librustc_mir/Cargo.toml
index f0cdcf2136bfa..8c62640353a9e 100644
--- a/src/librustc_mir/Cargo.toml
+++ b/src/librustc_mir/Cargo.toml
@@ -26,4 +26,4 @@ rustc_serialize = { path = "../libserialize", package = "serialize" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
 rustc_apfloat = { path = "../librustc_apfloat" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_resolve/Cargo.toml b/src/librustc_resolve/Cargo.toml
index 08ce7fd520e30..33b2bd36b7ded 100644
--- a/src/librustc_resolve/Cargo.toml
+++ b/src/librustc_resolve/Cargo.toml
@@ -21,4 +21,4 @@ errors = { path = "../librustc_errors", package = "rustc_errors" }
 syntax_pos = { path = "../libsyntax_pos" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_metadata = { path = "../librustc_metadata" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_traits/Cargo.toml b/src/librustc_traits/Cargo.toml
index b86a3a5e9639b..a9b184a7b3068 100644
--- a/src/librustc_traits/Cargo.toml
+++ b/src/librustc_traits/Cargo.toml
@@ -16,4 +16,4 @@ rustc_target = { path = "../librustc_target" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
 chalk-engine = { version = "0.9.0", default-features=false }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_typeck/Cargo.toml b/src/librustc_typeck/Cargo.toml
index a6644258be280..60a7a2f45989c 100644
--- a/src/librustc_typeck/Cargo.toml
+++ b/src/librustc_typeck/Cargo.toml
@@ -17,7 +17,7 @@ rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_target = { path = "../librustc_target" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
 rustc_index = { path = "../librustc_index" }
diff --git a/src/libserialize/Cargo.toml b/src/libserialize/Cargo.toml
index c302bcf95dcad..96a0d51bc716d 100644
--- a/src/libserialize/Cargo.toml
+++ b/src/libserialize/Cargo.toml
@@ -10,4 +10,4 @@ path = "lib.rs"
 
 [dependencies]
 indexmap = "1"
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/libsyntax/Cargo.toml b/src/libsyntax/Cargo.toml
index 3ce47e6a7b8cd..b1839cc05cd1f 100644
--- a/src/libsyntax/Cargo.toml
+++ b/src/libsyntax/Cargo.toml
@@ -21,4 +21,4 @@ rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_index = { path = "../librustc_index" }
 rustc_lexer = { path = "../librustc_lexer" }
 rustc_target = { path = "../librustc_target" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/libsyntax/tokenstream.rs b/src/libsyntax/tokenstream.rs
index 7e0582797c7ac..a51d208704ade 100644
--- a/src/libsyntax/tokenstream.rs
+++ b/src/libsyntax/tokenstream.rs
@@ -243,7 +243,7 @@ impl TokenStream {
 
                 // Get the first stream. If it's `None`, create an empty
                 // stream.
-                let mut iter = streams.drain();
+                let mut iter = streams.drain(..);
                 let mut first_stream_lrc = iter.next().unwrap().0;
 
                 // Append the elements to the first stream, after reserving
diff --git a/src/libsyntax_expand/Cargo.toml b/src/libsyntax_expand/Cargo.toml
index f063753f59943..d98b9457a625f 100644
--- a/src/libsyntax_expand/Cargo.toml
+++ b/src/libsyntax_expand/Cargo.toml
@@ -22,5 +22,5 @@ rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_index = { path = "../librustc_index" }
 rustc_lexer = { path = "../librustc_lexer" }
 rustc_target = { path = "../librustc_target" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
diff --git a/src/libsyntax_ext/Cargo.toml b/src/libsyntax_ext/Cargo.toml
index 440873f3c2b2d..703d51e1c4c3b 100644
--- a/src/libsyntax_ext/Cargo.toml
+++ b/src/libsyntax_ext/Cargo.toml
@@ -15,7 +15,7 @@ fmt_macros = { path = "../libfmt_macros" }
 log = "0.4"
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_target = { path = "../librustc_target" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
 syntax_expand = { path = "../libsyntax_expand" }
 syntax_pos = { path = "../libsyntax_pos" }