diff --git a/Cargo.lock b/Cargo.lock
index e0d30647809a9..1b916576bc99c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1011,6 +1011,7 @@ dependencies = [
 name = "fmt_macros"
 version = "0.0.0"
 dependencies = [
+ "rustc_lexer",
  "syntax_pos",
 ]
 
@@ -2372,7 +2373,7 @@ version = "0.4.30"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf3d2011ab5c909338f7887f4fc896d35932e29146c12c8d01da6b22a80ba759"
 dependencies = [
- "unicode-xid",
+ "unicode-xid 0.1.0",
 ]
 
 [[package]]
@@ -3290,7 +3291,7 @@ dependencies = [
 name = "rustc_lexer"
 version = "0.1.0"
 dependencies = [
- "unicode-xid",
+ "unicode-xid 0.2.0",
 ]
 
 [[package]]
@@ -3368,6 +3369,7 @@ dependencies = [
  "rustc_apfloat",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_lexer",
  "rustc_target",
  "serialize",
  "smallvec",
@@ -3976,7 +3978,7 @@ checksum = "641e117d55514d6d918490e47102f7e08d096fdde360247e4a10f7a91a8478d3"
 dependencies = [
  "proc-macro2",
  "quote",
- "unicode-xid",
+ "unicode-xid 0.1.0",
 ]
 
 [[package]]
@@ -3988,7 +3990,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn",
- "unicode-xid",
+ "unicode-xid 0.1.0",
 ]
 
 [[package]]
@@ -4017,6 +4019,7 @@ dependencies = [
  "log",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_lexer",
  "rustc_target",
  "smallvec",
  "syntax",
@@ -4532,6 +4535,12 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fc72304796d0818e357ead4e000d19c9c174ab23dc11093ac919054d20a6a7fc"
 
+[[package]]
+name = "unicode-xid"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "826e7639553986605ec5979c7dd957c7895e93eabed50ab2ffa7f6128a75097c"
+
 [[package]]
 name = "unicode_categories"
 version = "0.1.1"
diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index 8cb48df14bfef..936bed482e6f5 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -119,18 +119,9 @@ fn main() {
         cmd.arg(format!("-Cdebuginfo={}", debuginfo_level));
     }
 
-    if env::var_os("RUSTC_DENY_WARNINGS").is_some() &&
-       env::var_os("RUSTC_EXTERNAL_TOOL").is_none() {
-        // When extending this list, add the new lints to the RUSTFLAGS of the
-        // build_bootstrap function of src/bootstrap/bootstrap.py as well as
-        // some code doesn't go through this `rustc` wrapper.
-        cmd.arg("-Dwarnings");
-        cmd.arg("-Drust_2018_idioms");
-        cmd.arg("-Dunused_lifetimes");
-        if use_internal_lints(crate_name) {
-            cmd.arg("-Zunstable-options");
-            cmd.arg("-Drustc::internal");
-        }
+    if use_internal_lints(crate_name) {
+        cmd.arg("-Zunstable-options");
+        cmd.arg("-Wrustc::internal");
     }
 
     if let Some(target) = target {
diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index 4162fe1df5086..03f02ea217ddf 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -631,8 +631,9 @@ def build_bootstrap(self):
         target_linker = self.get_toml("linker", build_section)
         if target_linker is not None:
             env["RUSTFLAGS"] += "-C linker=" + target_linker + " "
+        env["RUSTFLAGS"] += " -Wrust_2018_idioms -Wunused_lifetimes "
         if self.get_toml("deny-warnings", "rust") != "false":
-            env["RUSTFLAGS"] += "-Dwarnings -Drust_2018_idioms -Dunused_lifetimes "
+            env["RUSTFLAGS"] += "-Dwarnings "
 
         env["PATH"] = os.path.join(self.bin_root(), "bin") + \
             os.pathsep + env["PATH"]
diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 4f5de1ecd2b44..6f2bf5f397bc8 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -765,7 +765,9 @@ impl<'a> Builder<'a> {
         if cmd == "doc" || cmd == "rustdoc" {
             let my_out = match mode {
                 // This is the intended out directory for compiler documentation.
-                Mode::Rustc | Mode::ToolRustc | Mode::Codegen => self.compiler_doc_out(target),
+                Mode::Rustc | Mode::ToolRustc { .. } | Mode::Codegen => {
+                    self.compiler_doc_out(target)
+                }
                 _ => self.crate_doc_out(target),
             };
             let rustdoc = self.rustdoc(compiler);
@@ -797,8 +799,8 @@ impl<'a> Builder<'a> {
         }
 
         match mode {
-            Mode::Std | Mode::ToolBootstrap | Mode::ToolStd => {},
-            Mode::Rustc | Mode::Codegen | Mode::ToolRustc => {
+            Mode::Std | Mode::ToolBootstrap { .. } | Mode::ToolStd { .. } => {},
+            Mode::Rustc | Mode::Codegen | Mode::ToolRustc { .. } => {
                 // Build proc macros both for the host and the target
                 if target != compiler.host && cmd != "check" {
                     cargo.arg("-Zdual-proc-macros");
@@ -873,6 +875,28 @@ impl<'a> Builder<'a> {
             extra_args.push_str("-Zforce-unstable-if-unmarked");
         }
 
+        match mode {
+            Mode::ToolStd { in_tree: true } |
+            Mode::ToolRustc { in_tree: true } |
+            Mode::ToolBootstrap { in_tree: true } |
+            Mode::Std |
+            Mode::Rustc |
+            Mode::Codegen => {
+                // When extending this list, add the new lints to the RUSTFLAGS of the
+                // build_bootstrap function of src/bootstrap/bootstrap.py as well as
+                // some code doesn't go through this `rustc` wrapper.
+                extra_args.push_str(" -Wrust_2018_idioms");
+                extra_args.push_str(" -Wunused_lifetimes");
+            }
+            Mode::ToolStd { in_tree: false } |
+            Mode::ToolRustc { in_tree: false } |
+            Mode::ToolBootstrap { in_tree: false } => {}
+        }
+
+        if self.config.deny_warnings {
+            extra_args.push_str(" -Dwarnings");
+        }
+
         if !extra_args.is_empty() {
             cargo.env(
                 "RUSTFLAGS",
@@ -891,7 +915,11 @@ impl<'a> Builder<'a> {
         // the stage0 build means it uses libraries build by the stage0
         // compiler, but for tools we just use the precompiled libraries that
         // we've downloaded
-        let use_snapshot = mode == Mode::ToolBootstrap;
+        let use_snapshot = if let Mode::ToolBootstrap { .. } = mode {
+            true
+        } else {
+            false
+        };
         assert!(!use_snapshot || stage == 0 || self.local_rebuild);
 
         let maybe_sysroot = self.sysroot(compiler);
@@ -944,8 +972,9 @@ impl<'a> Builder<'a> {
         let debuginfo_level = match mode {
             Mode::Rustc | Mode::Codegen => self.config.rust_debuginfo_level_rustc,
             Mode::Std => self.config.rust_debuginfo_level_std,
-            Mode::ToolBootstrap | Mode::ToolStd |
-            Mode::ToolRustc => self.config.rust_debuginfo_level_tools,
+            Mode::ToolBootstrap { .. } | Mode::ToolStd { .. } | Mode::ToolRustc { .. } => {
+                self.config.rust_debuginfo_level_tools
+            }
         };
         cargo.env("RUSTC_DEBUGINFO_LEVEL", debuginfo_level.to_string());
 
@@ -1031,10 +1060,6 @@ impl<'a> Builder<'a> {
 
         cargo.env("RUSTC_VERBOSE", self.verbosity.to_string());
 
-        if self.config.deny_warnings {
-            cargo.env("RUSTC_DENY_WARNINGS", "1");
-        }
-
         // Throughout the build Cargo can execute a number of build scripts
         // compiling C/C++ code and we need to pass compilers, archivers, flags, etc
         // obtained previously to those build scripts.
diff --git a/src/bootstrap/check.rs b/src/bootstrap/check.rs
index 205a80c3a3a9e..9a806c6463975 100644
--- a/src/bootstrap/check.rs
+++ b/src/bootstrap/check.rs
@@ -3,7 +3,7 @@
 use crate::compile::{run_cargo, std_cargo, rustc_cargo, rustc_cargo_env,
                      add_to_sysroot};
 use crate::builder::{RunConfig, Builder, Kind, ShouldRun, Step};
-use crate::tool::{prepare_tool_cargo, SourceType};
+use crate::tool::prepare_tool_cargo;
 use crate::{Compiler, Mode};
 use crate::cache::{INTERNER, Interned};
 use std::path::PathBuf;
@@ -187,11 +187,10 @@ impl Step for Rustdoc {
 
         let mut cargo = prepare_tool_cargo(builder,
                                            compiler,
-                                           Mode::ToolRustc,
+                                           Mode::ToolRustc { in_tree: true },
                                            target,
                                            cargo_subcommand(builder.kind),
                                            "src/tools/rustdoc",
-                                           SourceType::InTree,
                                            &[]);
 
         println!("Checking rustdoc artifacts ({} -> {})", &compiler.host, target);
@@ -244,6 +243,7 @@ pub fn rustdoc_stamp(
     compiler: Compiler,
     target: Interned<String>,
 ) -> PathBuf {
-    builder.cargo_out(compiler, Mode::ToolRustc, target)
+    // doesn't really matter whether we're in-tree or not
+    builder.cargo_out(compiler, Mode::ToolRustc { in_tree: true }, target)
         .join(".rustdoc-check.stamp")
 }
diff --git a/src/bootstrap/doc.rs b/src/bootstrap/doc.rs
index 6faedc80ad3f5..b96efa05b380e 100644
--- a/src/bootstrap/doc.rs
+++ b/src/bootstrap/doc.rs
@@ -17,7 +17,7 @@ use build_helper::{t, up_to_date};
 
 use crate::util::symlink_dir;
 use crate::builder::{Builder, Compiler, RunConfig, ShouldRun, Step};
-use crate::tool::{self, prepare_tool_cargo, Tool, SourceType};
+use crate::tool::{self, prepare_tool_cargo, Tool};
 use crate::compile;
 use crate::cache::{INTERNER, Interned};
 use crate::config::Config;
@@ -633,7 +633,7 @@ impl Step for Rustdoc {
         builder.ensure(tool::Rustdoc { compiler: compiler });
 
         // Symlink compiler docs to the output directory of rustdoc documentation.
-        let out_dir = builder.stage_out(compiler, Mode::ToolRustc)
+        let out_dir = builder.stage_out(compiler, Mode::ToolRustc { in_tree: true })
             .join(target)
             .join("doc");
         t!(fs::create_dir_all(&out_dir));
@@ -643,11 +643,10 @@ impl Step for Rustdoc {
         let mut cargo = prepare_tool_cargo(
             builder,
             compiler,
-            Mode::ToolRustc,
+            Mode::ToolRustc { in_tree: true },
             target,
             "doc",
             "src/tools/rustdoc",
-            SourceType::InTree,
             &[]
         );
 
diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index 828865f10ffba..d9580b598155e 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -36,7 +36,7 @@ pub struct Flags {
     // This overrides the deny-warnings configuation option,
     // which passes -Dwarnings to the compiler invocations.
     //
-    // true => deny, false => allow
+    // true => deny, false => warn
     pub deny_warnings: Option<bool>,
 }
 
@@ -556,10 +556,10 @@ fn split(s: &[String]) -> Vec<String> {
 fn parse_deny_warnings(matches: &getopts::Matches) -> Option<bool> {
     match matches.opt_str("warnings").as_ref().map(|v| v.as_str()) {
         Some("deny") => Some(true),
-        Some("allow") => Some(false),
+        Some("warn") => Some(false),
         Some(value) => {
             eprintln!(
-                r#"invalid value for --warnings: {:?}, expected "allow" or "deny""#,
+                r#"invalid value for --warnings: {:?}, expected "warn" or "deny""#,
                 value,
                 );
             process::exit(1);
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 5d7581c8211be..ecfd5e754a704 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -304,19 +304,19 @@ pub enum Mode {
     /// "other" here is for miscellaneous sets of tools that are built using the
     /// bootstrap compiler in its entirety (target libraries and all).
     /// Typically these tools compile with stable Rust.
-    ToolBootstrap,
+    ToolBootstrap { in_tree: bool },
 
     /// Compile a tool which uses all libraries we compile (up to rustc).
     /// Doesn't use the stage0 compiler libraries like "other", and includes
     /// tools like rustdoc, cargo, rls, etc.
-    ToolStd,
-    ToolRustc,
+    ToolStd { in_tree: bool },
+    ToolRustc { in_tree: bool },
 }
 
 impl Mode {
     pub fn is_tool(&self) -> bool {
         match self {
-            Mode::ToolBootstrap | Mode::ToolRustc | Mode::ToolStd => true,
+            Mode::ToolBootstrap { .. } | Mode::ToolRustc { .. } | Mode::ToolStd { .. } => true,
             _ => false
         }
     }
@@ -528,8 +528,8 @@ impl Build {
             Mode::Std => "-std",
             Mode::Rustc => "-rustc",
             Mode::Codegen => "-codegen",
-            Mode::ToolBootstrap => "-bootstrap-tools",
-            Mode::ToolStd | Mode::ToolRustc => "-tools",
+            Mode::ToolBootstrap { .. } => "-bootstrap-tools",
+            Mode::ToolStd { .. } | Mode::ToolRustc { .. } => "-tools",
         };
         self.out.join(&*compiler.host)
                 .join(format!("stage{}{}", compiler.stage, suffix))
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 97b28ed9e96c8..3ee71f2caba0c 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -19,7 +19,7 @@ use crate::compile;
 use crate::dist;
 use crate::flags::Subcommand;
 use crate::native;
-use crate::tool::{self, Tool, SourceType};
+use crate::tool::{self, Tool};
 use crate::toolstate::ToolState;
 use crate::util::{self, dylib_path, dylib_path_var};
 use crate::Crate as CargoCrate;
@@ -213,11 +213,10 @@ impl Step for Cargo {
         });
         let mut cargo = tool::prepare_tool_cargo(builder,
                                                  compiler,
-                                                 Mode::ToolRustc,
+                                                 Mode::ToolRustc { in_tree: false },
                                                  self.host,
                                                  "test",
                                                  "src/tools/cargo",
-                                                 SourceType::Submodule,
                                                  &[]);
 
         if !builder.fail_fast {
@@ -279,11 +278,10 @@ impl Step for Rls {
 
         let mut cargo = tool::prepare_tool_cargo(builder,
                                                  compiler,
-                                                 Mode::ToolRustc,
+                                                 Mode::ToolRustc { in_tree: false },
                                                  host,
                                                  "test",
                                                  "src/tools/rls",
-                                                 SourceType::Submodule,
                                                  &[]);
 
         builder.add_rustc_lib_path(compiler, &mut cargo);
@@ -335,11 +333,10 @@ impl Step for Rustfmt {
 
         let mut cargo = tool::prepare_tool_cargo(builder,
                                                  compiler,
-                                                 Mode::ToolRustc,
+                                                 Mode::ToolRustc { in_tree: false },
                                                  host,
                                                  "test",
                                                  "src/tools/rustfmt",
-                                                 SourceType::Submodule,
                                                  &[]);
 
         let dir = testdir(builder, compiler.host);
@@ -392,11 +389,10 @@ impl Step for Miri {
             let mut cargo = tool::prepare_tool_cargo(
                 builder,
                 compiler,
-                Mode::ToolRustc,
+                Mode::ToolRustc { in_tree: false },
                 host,
                 "run",
                 "src/tools/miri",
-                SourceType::Submodule,
                 &[],
             );
             cargo
@@ -451,11 +447,10 @@ impl Step for Miri {
             let mut cargo = tool::prepare_tool_cargo(
                 builder,
                 compiler,
-                Mode::ToolRustc,
+                Mode::ToolRustc { in_tree: false },
                 host,
                 "test",
                 "src/tools/miri",
-                SourceType::Submodule,
                 &[],
             );
 
@@ -504,11 +499,10 @@ impl Step for CompiletestTest {
 
         let mut cargo = tool::prepare_tool_cargo(builder,
                                                  compiler,
-                                                 Mode::ToolBootstrap,
+                                                 Mode::ToolBootstrap { in_tree: true },
                                                  host,
                                                  "test",
                                                  "src/tools/compiletest",
-                                                 SourceType::InTree,
                                                  &[]);
 
         try_run(builder, &mut cargo);
@@ -551,11 +545,10 @@ impl Step for Clippy {
         if let Some(clippy) = clippy {
             let mut cargo = tool::prepare_tool_cargo(builder,
                                                  compiler,
-                                                 Mode::ToolRustc,
+                                                 Mode::ToolRustc { in_tree: false },
                                                  host,
                                                  "test",
                                                  "src/tools/clippy",
-                                                 SourceType::Submodule,
                                                  &[]);
 
             // clippy tests need to know about the stage sysroot
@@ -563,7 +556,7 @@ impl Step for Clippy {
             cargo.env("RUSTC_TEST_SUITE", builder.rustc(compiler));
             cargo.env("RUSTC_LIB_PATH", builder.rustc_libdir(compiler));
             let host_libs = builder
-                .stage_out(compiler, Mode::ToolRustc)
+                .stage_out(compiler, Mode::ToolRustc { in_tree: false })
                 .join(builder.cargo_dir());
             cargo.env("HOST_LIBS", host_libs);
             // clippy tests need to find the driver
@@ -1877,11 +1870,10 @@ impl Step for CrateRustdoc {
 
         let mut cargo = tool::prepare_tool_cargo(builder,
                                                  compiler,
-                                                 Mode::ToolRustc,
+                                                 Mode::ToolRustc { in_tree: true },
                                                  target,
                                                  test_kind.subcommand(),
                                                  "src/tools/rustdoc",
-                                                 SourceType::InTree,
                                                  &[]);
         if test_kind.subcommand() == "test" && !builder.fail_fast {
             cargo.arg("--no-fail-fast");
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index 54fe26f18e741..3b88dc0abf0df 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -16,12 +16,6 @@ use crate::channel;
 use crate::cache::Interned;
 use crate::toolstate::ToolState;
 
-#[derive(Debug, Clone, Hash, PartialEq, Eq)]
-pub enum SourceType {
-    InTree,
-    Submodule,
-}
-
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 struct ToolBuild {
     compiler: Compiler,
@@ -30,7 +24,6 @@ struct ToolBuild {
     path: &'static str,
     mode: Mode,
     is_optional_tool: bool,
-    source_type: SourceType,
     extra_features: Vec<String>,
 }
 
@@ -53,13 +46,13 @@ impl Step for ToolBuild {
         let is_optional_tool = self.is_optional_tool;
 
         match self.mode {
-            Mode::ToolRustc => {
+            Mode::ToolRustc { .. } => {
                 builder.ensure(compile::Rustc { compiler, target })
             }
-            Mode::ToolStd => {
+            Mode::ToolStd { .. }=> {
                 builder.ensure(compile::Std { compiler, target })
             }
-            Mode::ToolBootstrap => {} // uses downloaded stage0 compiler libs
+            Mode::ToolBootstrap { .. } => {} // uses downloaded stage0 compiler libs
             _ => panic!("unexpected Mode for tool build")
         }
 
@@ -70,7 +63,6 @@ impl Step for ToolBuild {
             target,
             "build",
             path,
-            self.source_type,
             &self.extra_features,
         );
 
@@ -227,7 +219,6 @@ pub fn prepare_tool_cargo(
     target: Interned<String>,
     command: &'static str,
     path: &'static str,
-    source_type: SourceType,
     extra_features: &[String],
 ) -> Command {
     let mut cargo = builder.cargo(compiler, mode, target, command);
@@ -238,10 +229,6 @@ pub fn prepare_tool_cargo(
     // stages and such and it's just easier if they're not dynamically linked.
     cargo.env("RUSTC_NO_PREFER_DYNAMIC", "1");
 
-    if source_type == SourceType::Submodule {
-        cargo.env("RUSTC_EXTERNAL_TOOL", "1");
-    }
-
     let mut features = extra_features.iter().cloned().collect::<Vec<_>>();
     if builder.build.config.cargo_native_static {
         if path.ends_with("cargo") ||
@@ -357,14 +344,9 @@ macro_rules! bootstrap_tool {
                     compiler: self.compiler,
                     target: self.target,
                     tool: $tool_name,
-                    mode: Mode::ToolBootstrap,
+                    mode: Mode::ToolBootstrap { in_tree: true $(&& !$external)* },
                     path: $path,
                     is_optional_tool: false,
-                    source_type: if false $(|| $external)* {
-                        SourceType::Submodule
-                    } else {
-                        SourceType::InTree
-                    },
                     extra_features: {
                         // FIXME(#60643): avoid this lint by using `_`
                         let mut _tmp = Vec::new();
@@ -430,10 +412,9 @@ impl Step for ErrorIndex {
             compiler: self.compiler,
             target: self.compiler.host,
             tool: "error_index_generator",
-            mode: Mode::ToolRustc,
+            mode: Mode::ToolRustc { in_tree: true },
             path: "src/tools/error_index_generator",
             is_optional_tool: false,
-            source_type: SourceType::InTree,
             extra_features: Vec::new(),
         }).expect("expected to build -- essential tool")
     }
@@ -464,10 +445,9 @@ impl Step for RemoteTestServer {
             compiler: self.compiler,
             target: self.target,
             tool: "remote-test-server",
-            mode: Mode::ToolStd,
+            mode: Mode::ToolStd { in_tree: true },
             path: "src/tools/remote-test-server",
             is_optional_tool: false,
-            source_type: SourceType::InTree,
             extra_features: Vec::new(),
         }).expect("expected to build -- essential tool")
     }
@@ -520,11 +500,10 @@ impl Step for Rustdoc {
         let mut cargo = prepare_tool_cargo(
             builder,
             build_compiler,
-            Mode::ToolRustc,
+            Mode::ToolRustc { in_tree: true },
             target,
             "build",
             "src/tools/rustdoc",
-            SourceType::InTree,
             &[],
         );
 
@@ -535,8 +514,9 @@ impl Step for Rustdoc {
         // Cargo adds a number of paths to the dylib search path on windows, which results in
         // the wrong rustdoc being executed. To avoid the conflicting rustdocs, we name the "tool"
         // rustdoc a different name.
-        let tool_rustdoc = builder.cargo_out(build_compiler, Mode::ToolRustc, target)
-            .join(exe("rustdoc_tool_binary", &target_compiler.host));
+        let tool_rustdoc = builder.cargo_out(
+            build_compiler, Mode::ToolRustc { in_tree: true }, target
+        ).join(exe("rustdoc_tool_binary", &target_compiler.host));
 
         // don't create a stage0-sysroot/bin directory.
         if target_compiler.stage > 0 {
@@ -581,10 +561,9 @@ impl Step for Cargo {
             compiler: self.compiler,
             target: self.target,
             tool: "cargo",
-            mode: Mode::ToolRustc,
+            mode: Mode::ToolRustc { in_tree: true },
             path: "src/tools/cargo",
             is_optional_tool: false,
-            source_type: SourceType::Submodule,
             extra_features: Vec::new(),
         }).expect("expected to build -- essential tool")
     }
@@ -630,11 +609,10 @@ macro_rules! tool_extended {
                     compiler: $sel.compiler,
                     target: $sel.target,
                     tool: $tool_name,
-                    mode: Mode::ToolRustc,
+                    mode: Mode::ToolRustc { in_tree: false },
                     path: $path,
                     extra_features: $sel.extra_features,
                     is_optional_tool: true,
-                    source_type: SourceType::Submodule,
                 })
             }
         }
@@ -674,7 +652,8 @@ impl<'a> Builder<'a> {
         // right location to run `compiler`.
         let mut lib_paths: Vec<PathBuf> = vec![
             self.build.rustc_snapshot_libdir(),
-            self.cargo_out(compiler, Mode::ToolBootstrap, *host).join("deps"),
+            // doesn't really matter here whether we're in tree or not so just pass true
+            self.cargo_out(compiler, Mode::ToolBootstrap { in_tree: true }, *host).join("deps"),
         ];
 
         // On MSVC a tool may invoke a C compiler (e.g., compiletest in run-make
diff --git a/src/doc/unstable-book/src/language-features/plugin.md b/src/doc/unstable-book/src/language-features/plugin.md
index 53e8393ec52e4..68877b48433d5 100644
--- a/src/doc/unstable-book/src/language-features/plugin.md
+++ b/src/doc/unstable-book/src/language-features/plugin.md
@@ -57,12 +57,12 @@ extern crate rustc;
 extern crate rustc_driver;
 
 use syntax::parse::token::{self, Token};
-use syntax::tokenstream::TokenTree;
+use syntax::tokenstream::{TokenTree, TokenStream};
 use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacEager};
 use syntax_pos::Span;
 use rustc_driver::plugin::Registry;
 
-fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
+fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: TokenStream)
         -> Box<dyn MacResult + 'static> {
 
     static NUMERALS: &'static [(&'static str, usize)] = &[
@@ -78,7 +78,7 @@ fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
         return DummyResult::any(sp);
     }
 
-    let text = match args[0] {
+    let text = match args.into_trees().next().unwrap() {
         TokenTree::Token(Token { kind: token::Ident(s, _), .. }) => s.to_string(),
         _ => {
             cx.span_err(sp, "argument should be a single identifier");
diff --git a/src/libcore/char/methods.rs b/src/libcore/char/methods.rs
index e91bf53c5b418..a69eb0f6d4b20 100644
--- a/src/libcore/char/methods.rs
+++ b/src/libcore/char/methods.rs
@@ -547,29 +547,6 @@ impl char {
         }
     }
 
-    /// Returns `true` if this `char` satisfies the `XID_Start` Unicode property, and false
-    /// otherwise.
-    ///
-    /// `XID_Start` is a Unicode Derived Property specified in
-    /// [UAX #31](http://unicode.org/reports/tr31/#NFKC_Modifications),
-    /// mostly similar to `ID_Start` but modified for closure under `NFKx`.
-    #[unstable(feature = "unicode_internals", issue = "0")]
-    pub fn is_xid_start(self) -> bool {
-        derived_property::XID_Start(self)
-    }
-
-    /// Returns `true` if this `char` satisfies the `XID_Continue` Unicode property, and false
-    /// otherwise.
-    ///
-    /// `XID_Continue` is a Unicode Derived Property specified in
-    /// [UAX #31](http://unicode.org/reports/tr31/#NFKC_Modifications),
-    /// mostly similar to `ID_Continue` but modified for closure under NFKx.
-    #[unstable(feature = "unicode_internals", issue = "0")]
-    #[inline]
-    pub fn is_xid_continue(self) -> bool {
-        derived_property::XID_Continue(self)
-    }
-
     /// Returns `true` if this `char` is lowercase.
     ///
     /// 'Lowercase' is defined according to the terms of the Unicode Derived Core
diff --git a/src/libcore/unicode/mod.rs b/src/libcore/unicode/mod.rs
index 272727def61d6..a3ec9fd51f064 100644
--- a/src/libcore/unicode/mod.rs
+++ b/src/libcore/unicode/mod.rs
@@ -13,8 +13,3 @@ pub mod derived_property {
 pub mod conversions {
     pub use crate::unicode::tables::conversions::{to_lower, to_upper};
 }
-
-// For use in libsyntax
-pub mod property {
-    pub use crate::unicode::tables::property::Pattern_White_Space;
-}
diff --git a/src/libcore/unicode/tables.rs b/src/libcore/unicode/tables.rs
index 3fae3a46ada6b..5b5be48543121 100644
--- a/src/libcore/unicode/tables.rs
+++ b/src/libcore/unicode/tables.rs
@@ -890,384 +890,9 @@ pub(crate) mod derived_property {
         Uppercase_table.lookup(c)
     }
 
-    const XID_Continue_table: &super::BoolTrie = &super::BoolTrie {
-        r1: [
-            0x03ff000000000000, 0x07fffffe87fffffe, 0x04a0040000000000, 0xff7fffffff7fffff,
-            0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff,
-            0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0x0000501f0003ffc3,
-            0xffffffffffffffff, 0xb8dfffffffffffff, 0xfffffffbffffd7c0, 0xffbfffffffffffff,
-            0xffffffffffffffff, 0xffffffffffffffff, 0xfffffffffffffcfb, 0xffffffffffffffff,
-            0xfffeffffffffffff, 0xffffffff027fffff, 0xbffffffffffe01ff, 0x000787ffffff00b6,
-            0xffffffff07ff0000, 0xffffc3ffffffffff, 0xffffffffffffffff, 0x9ffffdff9fefffff,
-            0xffffffffffff0000, 0xffffffffffffe7ff, 0x0003ffffffffffff, 0x243fffffffffffff
-        ],
-        r2: [
-            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
-            24, 25, 26, 27, 28, 29, 30, 31, 4, 32, 33, 34, 4, 4, 4, 4, 4, 35, 36, 37, 38, 39, 40,
-            41, 42, 4, 4, 4, 4, 4, 4, 4, 4, 43, 44, 45, 46, 47, 4, 48, 49, 50, 51, 52, 53, 54, 55,
-            56, 57, 58, 59, 60, 4, 61, 4, 62, 63, 64, 65, 66, 4, 4, 4, 67, 4, 4, 4, 4, 68, 69, 70,
-            71, 72, 73, 74, 75, 76, 77, 78, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60,
-            60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60,
-            60, 60, 60, 60, 60, 79, 80, 4, 81, 82, 83, 84, 85, 60, 60, 60, 60, 60, 60, 60, 60, 86,
-            42, 87, 88, 89, 4, 90, 91, 60, 60, 60, 60, 60, 60, 60, 60, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 52, 60, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 92, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 93, 94, 4, 4, 4, 4, 95, 96, 4, 97, 98, 4, 99, 100, 101, 62, 4, 102, 103,
-            104, 4, 105, 106, 107, 4, 108, 109, 110, 4, 111, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 112, 113, 60, 60, 60, 60, 60, 60, 60,
-            60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60,
-            60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60,
-            60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60,
-            60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60,
-            60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60,
-            60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 4, 4, 4, 4, 4, 103, 4, 114,
-            115, 116, 97, 117, 4, 118, 4, 4, 119, 120, 121, 122, 123, 124, 4, 125, 126, 127, 128,
-            129
-        ],
-        r3: &[
-            0x00003fffffffffff, 0x000007ff0fffffff, 0x3fdfffff00000000, 0xfffffffbfff80000,
-            0xffffffffffffffff, 0xfffeffcfffffffff, 0xf3c5fdfffff99fef, 0x5003ffcfb080799f,
-            0xd36dfdfffff987ee, 0x003fffc05e023987, 0xf3edfdfffffbbfee, 0xfe00ffcf00013bbf,
-            0xf3edfdfffff99fee, 0x0002ffcfb0c0399f, 0xc3ffc718d63dc7ec, 0x0000ffc000813dc7,
-            0xe3fffdfffffddfff, 0x0000ffcf07603ddf, 0xf3effdfffffddfef, 0x0006ffcf40603ddf,
-            0xfffffffffffddfef, 0xfc00ffcf80f07ddf, 0x2ffbfffffc7fffec, 0x000cffc0ff5f847f,
-            0x07fffffffffffffe, 0x0000000003ff7fff, 0x3fffffaffffff7d6, 0x00000000f3ff3f5f,
-            0xc2a003ff03000001, 0xfffe1ffffffffeff, 0x1ffffffffeffffdf, 0x0000000000000040,
-            0xffffffffffff03ff, 0xffffffff3fffffff, 0xf7ffffffffff20bf, 0xffffffff3d7f3dff,
-            0x7f3dffffffff3dff, 0xffffffffff7fff3d, 0xffffffffff3dffff, 0x0003fe00e7ffffff,
-            0xffffffff0000ffff, 0x3f3fffffffffffff, 0xfffffffffffffffe, 0xffff9fffffffffff,
-            0xffffffff07fffffe, 0x01ffc7ffffffffff, 0x001fffff001fdfff, 0x000ddfff000fffff,
-            0x000003ff308fffff, 0xffffffff03ff3800, 0x01ffffffffffffff, 0xffff07ffffffffff,
-            0x003fffffffffffff, 0x0fff0fff7fffffff, 0x001f3fffffffffc0, 0xffff0fffffffffff,
-            0x0000000007ff03ff, 0xffffffff0fffffff, 0x9fffffff7fffffff, 0x3fff008003ff03ff,
-            0x0000000000000000, 0x000ff80003ff0fff, 0x000fffffffffffff, 0x00ffffffffffffff,
-            0x3fffffffffffe3ff, 0xe7ffffffffff01ff, 0x07fffffffff70000, 0xfbffffffffffffff,
-            0xffffffff3f3fffff, 0x3fffffffaaff3f3f, 0x5fdfffffffffffff, 0x1fdc1fff0fcf1fdc,
-            0x8000000000000000, 0x8002000000100001, 0x000000001fff0000, 0x0001ffe21fff0000,
-            0xf3fffd503f2ffc84, 0xffffffff000043e0, 0x00000000000001ff, 0xffff7fffffffffff,
-            0xffffffff7fffffff, 0x000ff81fffffffff, 0xffff20bfffffffff, 0x800080ffffffffff,
-            0x7f7f7f7f007fffff, 0xffffffff7f7f7f7f, 0x1f3efffe000000e0, 0xfffffffee67fffff,
-            0xf7ffffffffffffff, 0xfffeffffffffffe0, 0x07ffffff00007fff, 0xffff000000000000,
-            0x0000ffffffffffff, 0x0000000000001fff, 0x3fffffffffff0000, 0x00000fffffff1fff,
-            0xbff0ffffffffffff, 0x0003ffffffffffff, 0xfffffffcff800000, 0xfffffffffffff9ff,
-            0xff8000000000007c, 0x000000ffffffffff, 0xe8ffffff03ff003f, 0xffff3fffffffffff,
-            0x1fffffff000fffff, 0x7fffffff03ff8001, 0x007fffffffffffff, 0xfc7fffff03ff3fff,
-            0x007cffff38000007, 0xffff7f7f007e7e7e, 0xffff00fff7ffffff, 0x03ff37ffffffffff,
-            0xffff000fffffffff, 0x0ffffffffffff87f, 0x0000000003ffffff, 0x5f7ffdffe0f8007f,
-            0xffffffffffffffdb, 0xfffffffffff80000, 0xfffffff03fffffff, 0x3fffffffffffffff,
-            0xffffffffffff0000, 0xfffffffffffcffff, 0x03ff0000000000ff, 0x0018ffff0000ffff,
-            0xaa8a00000000e000, 0x1fffffffffffffff, 0x87fffffe03ff0000, 0xffffffc007fffffe,
-            0x7fffffffffffffff, 0x000000001cfcfcfc
-        ],
-        r4: [
-            0, 1, 2, 3, 4, 5, 6, 7, 8, 5, 5, 9, 5, 10, 11, 5, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 12, 13,
-            14, 7, 15, 16, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 17, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
-        ],
-        r5: &[
-            0, 1, 2, 3, 4, 5, 4, 6, 4, 4, 7, 8, 9, 10, 11, 12, 2, 2, 13, 14, 15, 16, 4, 4, 2, 2, 2,
-            2, 17, 18, 4, 4, 19, 20, 21, 22, 23, 4, 24, 4, 25, 26, 27, 28, 29, 30, 31, 4, 2, 32, 33,
-            33, 34, 4, 4, 4, 4, 4, 4, 4, 35, 36, 4, 37, 2, 38, 3, 39, 40, 41, 2, 42, 43, 4, 44, 45,
-            46, 47, 4, 4, 2, 48, 2, 49, 4, 4, 50, 51, 2, 52, 53, 54, 55, 4, 4, 4, 3, 4, 56, 57, 4,
-            4, 58, 59, 60, 61, 62, 53, 4, 4, 4, 4, 63, 64, 65, 4, 66, 67, 68, 4, 4, 4, 4, 37, 4, 4,
-            4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 69, 4, 2, 70, 2, 2, 2, 71, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 70, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 72, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 2, 2, 2, 2, 2, 2, 2, 2, 53, 73, 4, 74, 17, 75, 76, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2,
-            4, 4, 2, 77, 78, 79, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 80, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 33, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 2, 21, 81, 2, 2, 2, 2,
-            2, 82, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 83, 84, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 85, 86, 4, 4, 87, 4, 4, 4, 4, 4, 4, 2, 88, 89, 90, 91, 92, 2, 2, 2, 2, 93, 94, 95,
-            96, 97, 98, 4, 4, 4, 4, 4, 4, 4, 4, 99, 100, 101, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 102, 4, 4, 4, 103, 104, 4, 4, 4, 4, 4, 105, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 106, 2, 107, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 108, 109, 110, 4, 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 111, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 5, 2, 2, 2, 11,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 112, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 113, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 114, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 115, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
-        ],
-        r6: &[
-            0xb7ffff7fffffefff, 0x000000003fff3fff, 0xffffffffffffffff, 0x07ffffffffffffff,
-            0x0000000000000000, 0x001fffffffffffff, 0x2000000000000000, 0xffffffff1fffffff,
-            0x000000010001ffff, 0xffffe000ffffffff, 0x07ffffffffff07ff, 0xffffffff3fffffff,
-            0x00000000003eff0f, 0xffff03ff3fffffff, 0x0fffffffff0fffff, 0xffff00ffffffffff,
-            0x0000000fffffffff, 0x007fffffffffffff, 0x000000ff003fffff, 0x91bffffffffffd3f,
-            0x007fffff003fffff, 0x000000007fffffff, 0x0037ffff00000000, 0x03ffffff003fffff,
-            0xc0ffffffffffffff, 0x873ffffffeeff06f, 0x1fffffff00000000, 0x000000001fffffff,
-            0x0000007ffffffeff, 0x003fffffffffffff, 0x0007ffff003fffff, 0x000000000003ffff,
-            0x00000000000001ff, 0x0007ffffffffffff, 0x03ff00ffffffffff, 0xffff00801fffffff,
-            0x000000000001ffff, 0x007fffff00000000, 0x8000ffc00000007f, 0x03ff01ffffff0000,
-            0xffdfffffffffffff, 0x004fffffffff0070, 0x0000000017ff1e1f, 0x40fffffffffbffff,
-            0xffff01ffbfffbd7f, 0x03ff07ffffffffff, 0xfbedfdfffff99fef, 0x001f1fcfe081399f,
-            0x00000000c3ff07ff, 0x0000000003ff00bf, 0xff3fffffffffffff, 0x000000003f000001,
-            0x0000000003ff0011, 0x01ffffffffffffff, 0x00000000000003ff, 0x03ff0fffe7ffffff,
-            0xffffffff00000000, 0x800003ffffffffff, 0xfffffcff00000000, 0x0000001bfcffffff,
-            0x7fffffffffffffff, 0xffffffffffff0080, 0x0000000023ffffff, 0xff7ffffffffffdff,
-            0xfffc000003ff0001, 0x007ffefffffcffff, 0xb47ffffffffffb7f, 0xfffffdbf03ff00ff,
-            0x000003ff01fb7fff, 0x0000000003ffffff, 0x00007fffffffffff, 0x000000000000000f,
-            0x000000000000007f, 0x000003ff7fffffff, 0x001f3fffffff0000, 0xe0fffff803ff000f,
-            0x000000000000ffff, 0xffffffffffff87ff, 0x00000000ffff80ff, 0x0000000b00000000,
-            0x00ffffffffffffff, 0xffff00f000070000, 0x0fffffffffffffff, 0x1fff07ffffffffff,
-            0x0000000063ff01ff, 0xf807e3e000000000, 0x00003c0000000fe7, 0x000000000000001c,
-            0xffffffffffdfffff, 0xebffde64dfffffff, 0xffffffffffffffef, 0x7bffffffdfdfe7bf,
-            0xfffffffffffdfc5f, 0xffffff3fffffffff, 0xf7fffffff7fffffd, 0xffdfffffffdfffff,
-            0xffff7fffffff7fff, 0xfffffdfffffffdff, 0xffffffffffffcff7, 0xf87fffffffffffff,
-            0x00201fffffffffff, 0x0000fffef8000010, 0x000007dbf9ffff7f, 0x3fff1fffffffffff,
-            0x00000000000043ff, 0x03ffffffffffffff, 0x00000000007f001f, 0x0000000003ff0fff,
-            0x0af7fe96ffffffef, 0x5ef7f796aa96ea84, 0x0ffffbee0ffffbff, 0x00000000007fffff,
-            0xffff0003ffffffff, 0x00000001ffffffff, 0x000000003fffffff, 0x0000ffffffffffff
-        ],
-    };
-
-    pub fn XID_Continue(c: char) -> bool {
-        XID_Continue_table.lookup(c)
-    }
-
-    const XID_Start_table: &super::BoolTrie = &super::BoolTrie {
-        r1: [
-            0x0000000000000000, 0x07fffffe07fffffe, 0x0420040000000000, 0xff7fffffff7fffff,
-            0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff,
-            0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0x0000501f0003ffc3,
-            0x0000000000000000, 0xb8df000000000000, 0xfffffffbffffd740, 0xffbfffffffffffff,
-            0xffffffffffffffff, 0xffffffffffffffff, 0xfffffffffffffc03, 0xffffffffffffffff,
-            0xfffeffffffffffff, 0xffffffff027fffff, 0x00000000000001ff, 0x000787ffffff0000,
-            0xffffffff00000000, 0xfffec000000007ff, 0xffffffffffffffff, 0x9c00c060002fffff,
-            0x0000fffffffd0000, 0xffffffffffffe000, 0x0002003fffffffff, 0x043007fffffffc00
-        ],
-        r2: [
-            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
-            24, 23, 25, 26, 27, 28, 29, 3, 30, 31, 32, 33, 34, 34, 34, 34, 34, 35, 36, 37, 38, 39,
-            40, 41, 42, 34, 34, 34, 34, 34, 34, 34, 34, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
-            54, 55, 56, 57, 58, 59, 60, 3, 61, 62, 63, 64, 65, 66, 67, 68, 34, 34, 34, 3, 34, 34,
-            34, 34, 69, 70, 71, 72, 3, 73, 74, 3, 75, 76, 77, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-            3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 78,
-            79, 34, 80, 81, 82, 83, 84, 3, 3, 3, 3, 3, 3, 3, 3, 85, 42, 86, 87, 88, 34, 89, 90, 3,
-            3, 3, 3, 3, 3, 3, 3, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 53, 3, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 91, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 92, 93, 34, 34, 34, 34, 94,
-            95, 96, 91, 97, 34, 98, 99, 100, 48, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110,
-            111, 112, 34, 113, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34,
-            34, 34, 34, 114, 115, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-            3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-            3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-            3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-            3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 34, 34, 34, 34, 34,
-            116, 34, 117, 118, 119, 120, 121, 34, 122, 34, 34, 123, 124, 125, 126, 3, 127, 34, 128,
-            129, 130, 131, 132
-        ],
-        r3: &[
-            0x00000110043fffff, 0x000007ff01ffffff, 0x3fdfffff00000000, 0x0000000000000000,
-            0x23fffffffffffff0, 0xfffe0003ff010000, 0x23c5fdfffff99fe1, 0x10030003b0004000,
-            0x036dfdfffff987e0, 0x001c00005e000000, 0x23edfdfffffbbfe0, 0x0200000300010000,
-            0x23edfdfffff99fe0, 0x00020003b0000000, 0x03ffc718d63dc7e8, 0x0000000000010000,
-            0x23fffdfffffddfe0, 0x0000000307000000, 0x23effdfffffddfe1, 0x0006000340000000,
-            0x27fffffffffddfe0, 0xfc00000380704000, 0x2ffbfffffc7fffe0, 0x000000000000007f,
-            0x0005fffffffffffe, 0x2005ffaffffff7d6, 0x00000000f000005f, 0x0000000000000001,
-            0x00001ffffffffeff, 0x0000000000001f00, 0x800007ffffffffff, 0xffe1c0623c3f0000,
-            0xffffffff00004003, 0xf7ffffffffff20bf, 0xffffffffffffffff, 0xffffffff3d7f3dff,
-            0x7f3dffffffff3dff, 0xffffffffff7fff3d, 0xffffffffff3dffff, 0x0000000007ffffff,
-            0xffffffff0000ffff, 0x3f3fffffffffffff, 0xfffffffffffffffe, 0xffff9fffffffffff,
-            0xffffffff07fffffe, 0x01ffc7ffffffffff, 0x0003ffff0003dfff, 0x0001dfff0003ffff,
-            0x000fffffffffffff, 0x0000000010800000, 0xffffffff00000000, 0x01ffffffffffffff,
-            0xffff05ffffffffff, 0x003fffffffffffff, 0x000000007fffffff, 0x001f3fffffff0000,
-            0xffff0fffffffffff, 0x00000000000003ff, 0xffffffff007fffff, 0x00000000001fffff,
-            0x0000008000000000, 0x000fffffffffffe0, 0x0000000000000fe0, 0xfc00c001fffffff8,
-            0x0000003fffffffff, 0x0000000fffffffff, 0x3ffffffffc00e000, 0xe7ffffffffff01ff,
-            0x046fde0000000000, 0xffffffff3f3fffff, 0x3fffffffaaff3f3f, 0x5fdfffffffffffff,
-            0x1fdc1fff0fcf1fdc, 0x8002000000000000, 0x000000001fff0000, 0xf3fffd503f2ffc84,
-            0xffffffff000043e0, 0x00000000000001ff, 0xffff7fffffffffff, 0xffffffff7fffffff,
-            0x000c781fffffffff, 0xffff20bfffffffff, 0x000080ffffffffff, 0x7f7f7f7f007fffff,
-            0x000000007f7f7f7f, 0x1f3e03fe000000e0, 0xfffffffee07fffff, 0xf7ffffffffffffff,
-            0xfffeffffffffffe0, 0x07ffffff00007fff, 0xffff000000000000, 0x0000ffffffffffff,
-            0x0000000000001fff, 0x3fffffffffff0000, 0x00000c00ffff1fff, 0x80007fffffffffff,
-            0xffffffff3fffffff, 0xfffffffcff800000, 0xfffffffffffff9ff, 0xff8000000000007c,
-            0x00000007fffff7bb, 0x000ffffffffffffc, 0x68fc000000000000, 0xffff003ffffffc00,
-            0x1fffffff0000007f, 0x0007fffffffffff0, 0x7c00ffdf00008000, 0x000001ffffffffff,
-            0xc47fffff00000ff7, 0x3e62ffffffffffff, 0x001c07ff38000005, 0xffff7f7f007e7e7e,
-            0xffff00fff7ffffff, 0x00000007ffffffff, 0xffff000fffffffff, 0x0ffffffffffff87f,
-            0xffff3fffffffffff, 0x0000000003ffffff, 0x5f7ffdffa0f8007f, 0xffffffffffffffdb,
-            0x0003ffffffffffff, 0xfffffffffff80000, 0xfffffff03fffffff, 0x3fffffffffffffff,
-            0xffffffffffff0000, 0xfffffffffffcffff, 0x03ff0000000000ff, 0xaa8a000000000000,
-            0x1fffffffffffffff, 0x07fffffe00000000, 0xffffffc007fffffe, 0x7fffffff3fffffff,
-            0x000000001cfcfcfc
-        ],
-        r4: [
-            0, 1, 2, 3, 4, 5, 6, 7, 8, 5, 5, 9, 5, 10, 11, 5, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 12, 13,
-            14, 7, 15, 16, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-            5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
-        ],
-        r5: &[
-            0, 1, 2, 3, 4, 5, 4, 4, 4, 4, 6, 7, 8, 9, 10, 11, 2, 2, 12, 13, 14, 15, 4, 4, 2, 2, 2,
-            2, 16, 17, 4, 4, 18, 19, 20, 21, 22, 4, 23, 4, 24, 25, 26, 27, 28, 29, 30, 4, 2, 31, 32,
-            32, 15, 4, 4, 4, 4, 4, 4, 4, 33, 34, 4, 35, 36, 4, 37, 38, 39, 40, 41, 42, 43, 4, 44,
-            20, 45, 46, 4, 4, 5, 47, 48, 49, 4, 4, 50, 51, 48, 52, 53, 4, 54, 4, 4, 4, 55, 4, 56,
-            57, 4, 4, 58, 59, 60, 61, 62, 63, 4, 4, 4, 4, 64, 65, 66, 4, 67, 68, 69, 4, 4, 4, 4, 70,
-            4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 71, 4, 2, 50, 2, 2, 2, 72, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 50, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 73, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 63, 20, 4, 74, 48, 75, 66, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 2, 4, 4, 2, 76, 77, 78, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 79, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            32, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 2, 20, 80, 2,
-            2, 2, 2, 2, 81, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 82, 83, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 84, 85, 86, 87, 88, 2, 2, 2, 2, 89, 90,
-            91, 92, 93, 94, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 95, 96, 4, 4, 4, 4, 4, 55, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 97, 2, 98, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 99, 100, 101, 4, 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 102, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 5, 2, 2, 2, 10, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 103,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 104, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 105, 4, 4, 4, 4, 4, 4,
-            4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
-        ],
-        r6: &[
-            0xb7ffff7fffffefff, 0x000000003fff3fff, 0xffffffffffffffff, 0x07ffffffffffffff,
-            0x0000000000000000, 0x001fffffffffffff, 0xffffffff1fffffff, 0x000000000001ffff,
-            0xffffe000ffffffff, 0x003fffffffff07ff, 0xffffffff3fffffff, 0x00000000003eff0f,
-            0xffff00003fffffff, 0x0fffffffff0fffff, 0xffff00ffffffffff, 0x0000000fffffffff,
-            0x007fffffffffffff, 0x000000ff003fffff, 0x91bffffffffffd3f, 0x007fffff003fffff,
-            0x000000007fffffff, 0x0037ffff00000000, 0x03ffffff003fffff, 0xc0ffffffffffffff,
-            0x003ffffffeef0001, 0x1fffffff00000000, 0x000000001fffffff, 0x0000001ffffffeff,
-            0x003fffffffffffff, 0x0007ffff003fffff, 0x000000000003ffff, 0x00000000000001ff,
-            0x0007ffffffffffff, 0xffff00801fffffff, 0x000000000000003f, 0x007fffff00000000,
-            0x00fffffffffffff8, 0x0000fffffffffff8, 0x000001ffffff0000, 0x0000007ffffffff8,
-            0x0047ffffffff0010, 0x0007fffffffffff8, 0x000000001400001e, 0x00000ffffffbffff,
-            0xffff01ffbfffbd7f, 0x23edfdfffff99fe0, 0x00000003e0010000, 0x0000000080000780,
-            0x0000ffffffffffff, 0x00000000000000b0, 0x00007fffffffffff, 0x000000000f000000,
-            0x0000000000000010, 0x010007ffffffffff, 0x0000000007ffffff, 0x00000fffffffffff,
-            0xffffffff00000000, 0x80000000ffffffff, 0xfffffcff00000000, 0x0000000a0001ffff,
-            0x0407fffffffff801, 0xfffffffff0010000, 0x00000000200003ff, 0x01ffffffffffffff,
-            0x00007ffffffffdff, 0xfffc000000000001, 0x000000000000ffff, 0x0001fffffffffb7f,
-            0xfffffdbf00000040, 0x00000000010003ff, 0x0007ffff00000000, 0x0000000003ffffff,
-            0x000000000000000f, 0x000000000000007f, 0x00003fffffff0000, 0xe0fffff80000000f,
-            0x00000000000107ff, 0x00000000fff80000, 0x0000000b00000000, 0x00ffffffffffffff,
-            0xffff00f000070000, 0x0fffffffffffffff, 0x1fff07ffffffffff, 0x0000000003ff01ff,
-            0xffffffffffdfffff, 0xebffde64dfffffff, 0xffffffffffffffef, 0x7bffffffdfdfe7bf,
-            0xfffffffffffdfc5f, 0xffffff3fffffffff, 0xf7fffffff7fffffd, 0xffdfffffffdfffff,
-            0xffff7fffffff7fff, 0xfffffdfffffffdff, 0x0000000000000ff7, 0x3f801fffffffffff,
-            0x0000000000004000, 0x000000000000001f, 0x000000000000080f, 0x0af7fe96ffffffef,
-            0x5ef7f796aa96ea84, 0x0ffffbee0ffffbff, 0x00000000007fffff, 0xffff0003ffffffff,
-            0x00000001ffffffff, 0x000000003fffffff
-        ],
-    };
-
-    pub fn XID_Start(c: char) -> bool {
-        XID_Start_table.lookup(c)
-    }
-
 }
 
 pub(crate) mod property {
-    const Pattern_White_Space_table: &super::SmallBoolTrie = &super::SmallBoolTrie {
-        r1: &[
-            0, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3
-        ],
-        r2: &[
-            0x0000000100003e00, 0x0000000000000000, 0x0000000000000020, 0x000003000000c000
-        ],
-    };
-
-    pub fn Pattern_White_Space(c: char) -> bool {
-        Pattern_White_Space_table.lookup(c)
-    }
-
     const White_Space_table: &super::SmallBoolTrie = &super::SmallBoolTrie {
         r1: &[
             0, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
diff --git a/src/libcore/unicode/unicode.py b/src/libcore/unicode/unicode.py
index 6de5d9e033b93..89894f7932d79 100755
--- a/src/libcore/unicode/unicode.py
+++ b/src/libcore/unicode/unicode.py
@@ -728,7 +728,7 @@ def generate_property_module(mod, grouped_categories, category_subset):
 
     yield "pub(crate) mod %s {\n" % mod
     for cat in sorted(category_subset):
-        if cat in ("Cc", "White_Space", "Pattern_White_Space"):
+        if cat in ("Cc", "White_Space"):
             generator = generate_small_bool_trie("%s_table" % cat, grouped_categories[cat])
         else:
             generator = generate_bool_trie("%s_table" % cat, grouped_categories[cat])
@@ -841,19 +841,18 @@ def main():
     unicode_data = load_unicode_data(get_path(UnicodeFiles.UNICODE_DATA))
     load_special_casing(get_path(UnicodeFiles.SPECIAL_CASING), unicode_data)
 
-    want_derived = {"XID_Start", "XID_Continue", "Alphabetic", "Lowercase", "Uppercase",
+    want_derived = {"Alphabetic", "Lowercase", "Uppercase",
                     "Cased", "Case_Ignorable", "Grapheme_Extend"}
     derived = load_properties(get_path(UnicodeFiles.DERIVED_CORE_PROPERTIES), want_derived)
 
     props = load_properties(get_path(UnicodeFiles.PROPS),
-                            {"White_Space", "Join_Control", "Noncharacter_Code_Point",
-                             "Pattern_White_Space"})
+                            {"White_Space", "Join_Control", "Noncharacter_Code_Point"})
 
     # Category tables
     for (name, categories, category_subset) in (
             ("general_category", unicode_data.general_categories, ["N", "Cc"]),
             ("derived_property", derived, want_derived),
-            ("property", props, ["White_Space", "Pattern_White_Space"])
+            ("property", props, ["White_Space"])
     ):
         for fragment in generate_property_module(name, categories, category_subset):
             buf.write(fragment)
diff --git a/src/libfmt_macros/Cargo.toml b/src/libfmt_macros/Cargo.toml
index 82a9e34c065b1..fff4ec716dfda 100644
--- a/src/libfmt_macros/Cargo.toml
+++ b/src/libfmt_macros/Cargo.toml
@@ -10,4 +10,4 @@ path = "lib.rs"
 
 [dependencies]
 syntax_pos = { path = "../libsyntax_pos" }
-
+rustc_lexer = { path = "../librustc_lexer" }
diff --git a/src/libfmt_macros/lib.rs b/src/libfmt_macros/lib.rs
index 985abaf2c1bd5..f9c1be20b8bc1 100644
--- a/src/libfmt_macros/lib.rs
+++ b/src/libfmt_macros/lib.rs
@@ -597,12 +597,11 @@ impl<'a> Parser<'a> {
         }
     }
 
-    /// Parses a word starting at the current position. A word is considered to
-    /// be an alphabetic character followed by any number of alphanumeric
-    /// characters.
+    /// Parses a word starting at the current position. A word is the same as
+    /// Rust identifier, except that it can't start with `_` character.
     fn word(&mut self) -> &'a str {
         let start = match self.cur.peek() {
-            Some(&(pos, c)) if c.is_xid_start() => {
+            Some(&(pos, c)) if c != '_' && rustc_lexer::is_id_start(c) => {
                 self.cur.next();
                 pos
             }
@@ -611,7 +610,7 @@ impl<'a> Parser<'a> {
             }
         };
         while let Some(&(pos, c)) = self.cur.peek() {
-            if c.is_xid_continue() {
+            if rustc_lexer::is_id_continue(c) {
                 self.cur.next();
             } else {
                 return &self.input[start..pos];
diff --git a/src/librustc_lexer/Cargo.toml b/src/librustc_lexer/Cargo.toml
index 0dbcda618ecac..675d3065c5b28 100644
--- a/src/librustc_lexer/Cargo.toml
+++ b/src/librustc_lexer/Cargo.toml
@@ -4,12 +4,12 @@ name = "rustc_lexer"
 version = "0.1.0"
 edition = "2018"
 
-# Note that this crate purposefully does not depend on other rustc crates
-[dependencies]
-unicode-xid = { version = "0.1.0", optional = true }
-
 # Note: do not remove this blank `[lib]` section.
 # This will be used when publishing this crate as `rustc-ap-rustc_lexer`.
 [lib]
 doctest = false
 name = "rustc_lexer"
+
+# Note that this crate purposefully does not depend on other rustc crates
+[dependencies]
+unicode-xid = "0.2.0"
diff --git a/src/librustc_lexer/src/lib.rs b/src/librustc_lexer/src/lib.rs
index 41b47befaf141..30a5175d8cdb0 100644
--- a/src/librustc_lexer/src/lib.rs
+++ b/src/librustc_lexer/src/lib.rs
@@ -1,6 +1,5 @@
-// We want to be able to build this crate with a stable compiler, so feature
-// flags should be optional.
-#![cfg_attr(not(feature = "unicode-xid"), feature(unicode_internals))]
+// We want to be able to build this crate with a stable compiler, so no
+// `#![feature]` attributes should be added.
 
 mod cursor;
 pub mod unescape;
@@ -103,6 +102,62 @@ pub fn tokenize(mut input: &str) -> impl Iterator<Item = Token> + '_ {
     })
 }
 
+// See [UAX #31](http://unicode.org/reports/tr31) for definitions of these
+// classes.
+
+/// True if `c` is considered a whitespace according to Rust language definition.
+pub fn is_whitespace(c: char) -> bool {
+    // This is Pattern_White_Space.
+    //
+    // Note that this set is stable (ie, it doesn't change with different
+    // Unicode versions), so it's ok to just hard-code the values.
+
+    match c {
+        // Usual ASCII suspects
+        | '\u{0009}' // \t
+        | '\u{000A}' // \n
+        | '\u{000B}' // vertical tab
+        | '\u{000C}' // form feed
+        | '\u{000D}' // \r
+        | '\u{0020}' // space
+
+        // NEXT LINE from latin1
+        | '\u{0085}'
+
+        // Bidi markers
+        | '\u{200E}' // LEFT-TO-RIGHT MARK
+        | '\u{200F}' // RIGHT-TO-LEFT MARK
+
+        // Dedicated whitespace characters from Unicode
+        | '\u{2028}' // LINE SEPARATOR
+        | '\u{2029}' // PARAGRAPH SEPARATOR
+            => true,
+        _ => false,
+    }
+}
+
+/// True if `c` is valid as a first character of an identifier.
+pub fn is_id_start(c: char) -> bool {
+    // This is XID_Start OR '_' (which formally is not a XID_Start).
+    // We also add fast-path for ascii idents
+    ('a' <= c && c <= 'z')
+        || ('A' <= c && c <= 'Z')
+        || c == '_'
+        || (c > '\x7f' && unicode_xid::UnicodeXID::is_xid_start(c))
+}
+
+/// True if `c` is valid as a non-first character of an identifier.
+pub fn is_id_continue(c: char) -> bool {
+    // This is exactly XID_Continue.
+    // We also add fast-path for ascii idents
+    ('a' <= c && c <= 'z')
+        || ('A' <= c && c <= 'Z')
+        || ('0' <= c && c <= '9')
+        || c == '_'
+        || (c > '\x7f' && unicode_xid::UnicodeXID::is_xid_continue(c))
+}
+
+
 impl Cursor<'_> {
     fn advance_token(&mut self) -> Token {
         let first_char = self.bump().unwrap();
@@ -112,9 +167,9 @@ impl Cursor<'_> {
                 '*' => self.block_comment(),
                 _ => Slash,
             },
-            c if character_properties::is_whitespace(c) => self.whitespace(),
+            c if is_whitespace(c) => self.whitespace(),
             'r' => match (self.nth_char(0), self.nth_char(1)) {
-                ('#', c1) if character_properties::is_id_start(c1) => self.raw_ident(),
+                ('#', c1) if is_id_start(c1) => self.raw_ident(),
                 ('#', _) | ('"', _) => {
                     let (n_hashes, started, terminated) = self.raw_double_quoted_string();
                     let suffix_start = self.len_consumed();
@@ -159,7 +214,7 @@ impl Cursor<'_> {
                 }
                 _ => self.ident(),
             },
-            c if character_properties::is_id_start(c) => self.ident(),
+            c if is_id_start(c) => self.ident(),
             c @ '0'..='9' => {
                 let literal_kind = self.number(c);
                 let suffix_start = self.len_consumed();
@@ -247,8 +302,8 @@ impl Cursor<'_> {
     }
 
     fn whitespace(&mut self) -> TokenKind {
-        debug_assert!(character_properties::is_whitespace(self.prev()));
-        while character_properties::is_whitespace(self.nth_char(0)) {
+        debug_assert!(is_whitespace(self.prev()));
+        while is_whitespace(self.nth_char(0)) {
             self.bump();
         }
         Whitespace
@@ -258,19 +313,19 @@ impl Cursor<'_> {
         debug_assert!(
             self.prev() == 'r'
                 && self.nth_char(0) == '#'
-                && character_properties::is_id_start(self.nth_char(1))
+                && is_id_start(self.nth_char(1))
         );
         self.bump();
         self.bump();
-        while character_properties::is_id_continue(self.nth_char(0)) {
+        while is_id_continue(self.nth_char(0)) {
             self.bump();
         }
         RawIdent
     }
 
     fn ident(&mut self) -> TokenKind {
-        debug_assert!(character_properties::is_id_start(self.prev()));
-        while character_properties::is_id_continue(self.nth_char(0)) {
+        debug_assert!(is_id_start(self.prev()));
+        while is_id_continue(self.nth_char(0)) {
             self.bump();
         }
         Ident
@@ -315,7 +370,7 @@ impl Cursor<'_> {
             // integer literal followed by field/method access or a range pattern
             // (`0..2` and `12.foo()`)
             '.' if self.nth_char(1) != '.'
-                && !character_properties::is_id_start(self.nth_char(1)) =>
+                && !is_id_start(self.nth_char(1)) =>
             {
                 // might have stuff after the ., and if it does, it needs to start
                 // with a number
@@ -345,7 +400,7 @@ impl Cursor<'_> {
     fn lifetime_or_char(&mut self) -> TokenKind {
         debug_assert!(self.prev() == '\'');
         let mut starts_with_number = false;
-        if (character_properties::is_id_start(self.nth_char(0))
+        if (is_id_start(self.nth_char(0))
             || self.nth_char(0).is_digit(10) && {
                 starts_with_number = true;
                 true
@@ -353,7 +408,7 @@ impl Cursor<'_> {
             && self.nth_char(1) != '\''
         {
             self.bump();
-            while character_properties::is_id_continue(self.nth_char(0)) {
+            while is_id_continue(self.nth_char(0)) {
                 self.bump();
             }
 
@@ -495,66 +550,13 @@ impl Cursor<'_> {
     }
 
     fn eat_literal_suffix(&mut self) {
-        if !character_properties::is_id_start(self.nth_char(0)) {
+        if !is_id_start(self.nth_char(0)) {
             return;
         }
         self.bump();
 
-        while character_properties::is_id_continue(self.nth_char(0)) {
+        while is_id_continue(self.nth_char(0)) {
             self.bump();
         }
     }
 }
-
-pub mod character_properties {
-    // this is Pattern_White_Space
-    #[cfg(feature = "unicode-xid")]
-    pub fn is_whitespace(c: char) -> bool {
-        match c {
-            '\u{0009}' | '\u{000A}' | '\u{000B}' | '\u{000C}' | '\u{000D}' | '\u{0020}'
-            | '\u{0085}' | '\u{200E}' | '\u{200F}' | '\u{2028}' | '\u{2029}' => true,
-            _ => false,
-        }
-    }
-
-    #[cfg(not(feature = "unicode-xid"))]
-    pub fn is_whitespace(c: char) -> bool {
-        core::unicode::property::Pattern_White_Space(c)
-    }
-
-    // this is XID_Start OR '_' (which formally is not a XID_Start)
-    #[cfg(feature = "unicode-xid")]
-    pub fn is_id_start(c: char) -> bool {
-        ('a' <= c && c <= 'z')
-            || ('A' <= c && c <= 'Z')
-            || c == '_'
-            || (c > '\x7f' && unicode_xid::UnicodeXID::is_xid_start(c))
-    }
-
-    #[cfg(not(feature = "unicode-xid"))]
-    pub fn is_id_start(c: char) -> bool {
-        ('a' <= c && c <= 'z')
-            || ('A' <= c && c <= 'Z')
-            || c == '_'
-            || (c > '\x7f' && c.is_xid_start())
-    }
-
-    // this is XID_Continue
-    #[cfg(feature = "unicode-xid")]
-    pub fn is_id_continue(c: char) -> bool {
-        ('a' <= c && c <= 'z')
-            || ('A' <= c && c <= 'Z')
-            || ('0' <= c && c <= '9')
-            || c == '_'
-            || (c > '\x7f' && unicode_xid::UnicodeXID::is_xid_continue(c))
-    }
-
-    #[cfg(not(feature = "unicode-xid"))]
-    pub fn is_id_continue(c: char) -> bool {
-        ('a' <= c && c <= 'z')
-            || ('A' <= c && c <= 'Z')
-            || ('0' <= c && c <= '9')
-            || c == '_'
-            || (c > '\x7f' && c.is_xid_continue())
-    }
-}
diff --git a/src/librustc_metadata/encoder.rs b/src/librustc_metadata/encoder.rs
index db212408d8ebd..f430f01542efe 100644
--- a/src/librustc_metadata/encoder.rs
+++ b/src/librustc_metadata/encoder.rs
@@ -1354,7 +1354,7 @@ impl EncodeContext<'tcx> {
         let def_id = self.tcx.hir().local_def_id(macro_def.hir_id);
         Entry {
             kind: EntryKind::MacroDef(self.lazy(MacroDef {
-                body: pprust::tokens_to_string(macro_def.body.clone()),
+                body: pprust::tts_to_string(macro_def.body.clone()),
                 legacy: macro_def.legacy,
             })),
             visibility: self.lazy(ty::Visibility::Public),
diff --git a/src/librustc_mir/Cargo.toml b/src/librustc_mir/Cargo.toml
index 21008c737289f..4e68708adfc3e 100644
--- a/src/librustc_mir/Cargo.toml
+++ b/src/librustc_mir/Cargo.toml
@@ -20,6 +20,7 @@ rustc = { path = "../librustc" }
 rustc_target = { path = "../librustc_target" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_errors = { path = "../librustc_errors" }
+rustc_lexer = { path = "../librustc_lexer" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
diff --git a/src/librustc_mir/borrow_check/move_errors.rs b/src/librustc_mir/borrow_check/move_errors.rs
index f10ff71b15e68..0d13db2f5a413 100644
--- a/src/librustc_mir/borrow_check/move_errors.rs
+++ b/src/librustc_mir/borrow_check/move_errors.rs
@@ -1,5 +1,3 @@
-use core::unicode::property::Pattern_White_Space;
-
 use rustc::mir::*;
 use rustc::ty;
 use rustc_errors::{DiagnosticBuilder,Applicability};
@@ -526,7 +524,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                         let suggestion;
                         let to_remove;
                         if pat_snippet.starts_with("mut")
-                            && pat_snippet["mut".len()..].starts_with(Pattern_White_Space)
+                            && pat_snippet["mut".len()..].starts_with(rustc_lexer::is_whitespace)
                         {
                             suggestion = pat_snippet["mut".len()..].trim_start();
                             to_remove = "&mut";
diff --git a/src/librustc_mir/borrow_check/mutability_errors.rs b/src/librustc_mir/borrow_check/mutability_errors.rs
index 5a5534922aa8a..8f2ce80aafa22 100644
--- a/src/librustc_mir/borrow_check/mutability_errors.rs
+++ b/src/librustc_mir/borrow_check/mutability_errors.rs
@@ -1,4 +1,3 @@
-use core::unicode::property::Pattern_White_Space;
 use rustc::hir;
 use rustc::hir::Node;
 use rustc::mir::{self, BindingForm, ClearCrossCrate, Local, Location, Body};
@@ -715,7 +714,7 @@ fn annotate_struct_field(
 fn suggest_ref_mut(tcx: TyCtxt<'_>, binding_span: Span) -> Option<String> {
     let hi_src = tcx.sess.source_map().span_to_snippet(binding_span).ok()?;
     if hi_src.starts_with("ref")
-        && hi_src["ref".len()..].starts_with(Pattern_White_Space)
+        && hi_src["ref".len()..].starts_with(rustc_lexer::is_whitespace)
     {
         let replacement = format!("ref mut{}", &hi_src["ref".len()..]);
         Some(replacement)
diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs
index 23c9e7fdf67ce..f358bb00f4d12 100644
--- a/src/librustc_mir/interpret/place.rs
+++ b/src/librustc_mir/interpret/place.rs
@@ -585,8 +585,9 @@ where
         use rustc::mir::StaticKind;
 
         Ok(match place_static.kind {
-            StaticKind::Promoted(promoted, _) => {
-                let instance = self.frame().instance;
+            StaticKind::Promoted(promoted, promoted_substs) => {
+                let substs = self.subst_from_frame_and_normalize_erasing_regions(promoted_substs);
+                let instance = ty::Instance::new(place_static.def_id, substs);
                 self.const_eval_raw(GlobalId {
                     instance,
                     promoted: Some(promoted),
diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs
index f261fdc268b5b..e4b186736e2a1 100644
--- a/src/librustc_mir/transform/const_prop.rs
+++ b/src/librustc_mir/transform/const_prop.rs
@@ -405,13 +405,16 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                 }
 
                 let arg = self.eval_operand(arg, source_info)?;
+                let oflo_check = self.tcx.sess.overflow_checks();
                 let val = self.use_ecx(source_info, |this| {
                     let prim = this.ecx.read_immediate(arg)?;
                     match op {
                         UnOp::Neg => {
-                            // Need to do overflow check here: For actual CTFE, MIR
-                            // generation emits code that does this before calling the op.
-                            if prim.to_bits()? == (1 << (prim.layout.size.bits() - 1)) {
+                            // We check overflow in debug mode already
+                            // so should only check in release mode.
+                            if !oflo_check
+                            && prim.layout.ty.is_signed()
+                            && prim.to_bits()? == (1 << (prim.layout.size.bits() - 1)) {
                                 throw_panic!(OverflowNeg)
                             }
                         }
@@ -485,7 +488,9 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                         Scalar::from_bool(overflow).into(),
                     )
                 } else {
-                    if overflow {
+                    // We check overflow in debug mode already
+                    // so should only check in release mode.
+                    if !self.tcx.sess.overflow_checks() && overflow {
                         let err = err_panic!(Overflow(op)).into();
                         let _: Option<()> = self.use_ecx(source_info, |_| Err(err));
                         return None;
diff --git a/src/librustc_target/spec/linux_kernel_base.rs b/src/librustc_target/spec/linux_kernel_base.rs
new file mode 100644
index 0000000000000..fae44836fa821
--- /dev/null
+++ b/src/librustc_target/spec/linux_kernel_base.rs
@@ -0,0 +1,26 @@
+use crate::spec::{LinkArgs, LinkerFlavor, PanicStrategy, RelroLevel, TargetOptions};
+use std::default::Default;
+
+pub fn opts() -> TargetOptions {
+    let mut pre_link_args = LinkArgs::new();
+    pre_link_args.insert(
+        LinkerFlavor::Gcc,
+        vec!["-Wl,--as-needed".to_string(), "-Wl,-z,noexecstack".to_string()],
+    );
+
+    TargetOptions {
+        disable_redzone: true,
+        panic_strategy: PanicStrategy::Abort,
+        stack_probes: true,
+        eliminate_frame_pointer: false,
+        linker_is_gnu: true,
+        position_independent_executables: true,
+        needs_plt: true,
+        relro_level: RelroLevel::Full,
+        relocation_model: "static".to_string(),
+        target_family: Some("unix".to_string()),
+        pre_link_args,
+
+        ..Default::default()
+    }
+}
diff --git a/src/librustc_target/spec/mod.rs b/src/librustc_target/spec/mod.rs
index 539e28f7088e3..503d8a08b6f4f 100644
--- a/src/librustc_target/spec/mod.rs
+++ b/src/librustc_target/spec/mod.rs
@@ -53,6 +53,7 @@ mod freebsd_base;
 mod haiku_base;
 mod hermit_base;
 mod linux_base;
+mod linux_kernel_base;
 mod linux_musl_base;
 mod openbsd_base;
 mod netbsd_base;
@@ -386,6 +387,8 @@ supported_targets! {
     ("thumbv7neon-linux-androideabi", thumbv7neon_linux_androideabi),
     ("aarch64-linux-android", aarch64_linux_android),
 
+    ("x86_64-linux-kernel", x86_64_linux_kernel),
+
     ("aarch64-unknown-freebsd", aarch64_unknown_freebsd),
     ("armv6-unknown-freebsd", armv6_unknown_freebsd),
     ("armv7-unknown-freebsd", armv7_unknown_freebsd),
diff --git a/src/librustc_target/spec/x86_64_linux_kernel.rs b/src/librustc_target/spec/x86_64_linux_kernel.rs
new file mode 100644
index 0000000000000..a80b021208ed7
--- /dev/null
+++ b/src/librustc_target/spec/x86_64_linux_kernel.rs
@@ -0,0 +1,31 @@
+// This defines the amd64 target for the Linux Kernel. See the linux-kernel-base module for
+// generic Linux kernel options.
+
+use crate::spec::{LinkerFlavor, Target, TargetResult};
+
+pub fn target() -> TargetResult {
+    let mut base = super::linux_kernel_base::opts();
+    base.cpu = "x86-64".to_string();
+    base.max_atomic_width = Some(64);
+    base.features =
+        "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-3dnow,-3dnowa,-avx,-avx2,+soft-float"
+            .to_string();
+    base.code_model = Some("kernel".to_string());
+    base.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap().push("-m64".to_string());
+
+    Ok(Target {
+        // FIXME: Some dispute, the linux-on-clang folks think this should use "Linux"
+        llvm_target: "x86_64-elf".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "64".to_string(),
+        target_c_int_width: "32".to_string(),
+        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        target_os: "none".to_string(),
+        target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
+        arch: "x86_64".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+
+        options: base,
+    })
+}
diff --git a/src/librustdoc/html/static/main.js b/src/librustdoc/html/static/main.js
index 637c6ef8e8e0b..309e5575ee403 100644
--- a/src/librustdoc/html/static/main.js
+++ b/src/librustdoc/html/static/main.js
@@ -344,7 +344,7 @@ if (!DOMTokenList.prototype.remove) {
             var set_fragment = function(name) {
                 if (browserSupportsHistoryApi()) {
                     history.replaceState(null, null, "#" + name);
-                    window.hashchange();
+                    highlightSourceLines(null);
                 } else {
                     location.replace("#" + name);
                 }
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index dfa0db0d23b74..301946733dc55 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -33,6 +33,7 @@ extern crate rustc_interface;
 extern crate rustc_metadata;
 extern crate rustc_target;
 extern crate rustc_typeck;
+extern crate rustc_lexer;
 extern crate serialize;
 extern crate syntax;
 extern crate syntax_pos;
diff --git a/src/librustdoc/passes/check_code_block_syntax.rs b/src/librustdoc/passes/check_code_block_syntax.rs
index 5c4159433c7b2..32044e48b6f99 100644
--- a/src/librustdoc/passes/check_code_block_syntax.rs
+++ b/src/librustdoc/passes/check_code_block_syntax.rs
@@ -81,7 +81,7 @@ impl<'a, 'tcx> SyntaxChecker<'a, 'tcx> {
                 // We couldn't calculate the span of the markdown block that had the error, so our
                 // diagnostics are going to be a bit lacking.
                 let mut diag = self.cx.sess().struct_span_warn(
-                    super::span_of_attrs(&item.attrs),
+                    super::span_of_attrs(&item.attrs).unwrap_or(item.source.span()),
                     "doc comment contains an invalid Rust code block",
                 );
 
diff --git a/src/librustdoc/passes/collect_intra_doc_links.rs b/src/librustdoc/passes/collect_intra_doc_links.rs
index c73c46472d804..2951b2ccb2af9 100644
--- a/src/librustdoc/passes/collect_intra_doc_links.rs
+++ b/src/librustdoc/passes/collect_intra_doc_links.rs
@@ -465,7 +465,7 @@ fn resolution_failure(
         }
     };
     let attrs = &item.attrs;
-    let sp = span_of_attrs(attrs);
+    let sp = span_of_attrs(attrs).unwrap_or(item.source.span());
 
     let mut diag = cx.tcx.struct_span_lint_hir(
         lint::builtin::INTRA_DOC_LINK_RESOLUTION_FAILURE,
@@ -517,7 +517,7 @@ fn ambiguity_error(
         }
     };
     let attrs = &item.attrs;
-    let sp = span_of_attrs(attrs);
+    let sp = span_of_attrs(attrs).unwrap_or(item.source.span());
 
     let mut msg = format!("`{}` is ", path_str);
 
diff --git a/src/librustdoc/passes/mod.rs b/src/librustdoc/passes/mod.rs
index 641a6df221446..49a34c7e46281 100644
--- a/src/librustdoc/passes/mod.rs
+++ b/src/librustdoc/passes/mod.rs
@@ -339,7 +339,7 @@ pub fn look_for_tests<'tcx>(
     find_testable_code(&dox, &mut tests, ErrorCodes::No);
 
     if check_missing_code == true && tests.found_tests == 0 {
-        let sp = span_of_attrs(&item.attrs).substitute_dummy(item.source.span());
+        let sp = span_of_attrs(&item.attrs).unwrap_or(item.source.span());
         let mut diag = cx.tcx.struct_span_lint_hir(
             lint::builtin::MISSING_DOC_CODE_EXAMPLES,
             hir_id,
@@ -352,20 +352,23 @@ pub fn look_for_tests<'tcx>(
         let mut diag = cx.tcx.struct_span_lint_hir(
             lint::builtin::PRIVATE_DOC_TESTS,
             hir_id,
-            span_of_attrs(&item.attrs),
+            span_of_attrs(&item.attrs).unwrap_or(item.source.span()),
             "Documentation test in private item");
         diag.emit();
     }
 }
 
 /// Returns a span encompassing all the given attributes.
-crate fn span_of_attrs(attrs: &clean::Attributes) -> Span {
+crate fn span_of_attrs(attrs: &clean::Attributes) -> Option<Span> {
     if attrs.doc_strings.is_empty() {
-        return DUMMY_SP;
+        return None;
     }
     let start = attrs.doc_strings[0].span();
+    if start == DUMMY_SP {
+        return None;
+    }
     let end = attrs.doc_strings.last().expect("No doc strings provided").span();
-    start.to(end)
+    Some(start.to(end))
 }
 
 /// Attempts to match a range of bytes from parsed markdown to a `Span` in the source code.
@@ -391,7 +394,7 @@ crate fn source_span_for_markdown_range(
     let snippet = cx
         .sess()
         .source_map()
-        .span_to_snippet(span_of_attrs(attrs))
+        .span_to_snippet(span_of_attrs(attrs)?)
         .ok()?;
 
     let starting_line = markdown[..md_range.start].matches('\n').count();
@@ -441,10 +444,8 @@ crate fn source_span_for_markdown_range(
         }
     }
 
-    let sp = span_of_attrs(attrs).from_inner(InnerSpan::new(
+    Some(span_of_attrs(attrs)?.from_inner(InnerSpan::new(
         md_range.start + start_bytes,
         md_range.end + start_bytes + end_bytes,
-    ));
-
-    Some(sp)
+    )))
 }
diff --git a/src/librustdoc/test.rs b/src/librustdoc/test.rs
index adcc9930b6c33..000d2843adce3 100644
--- a/src/librustdoc/test.rs
+++ b/src/librustdoc/test.rs
@@ -763,8 +763,8 @@ impl Tester for Collector {
             // We use these headings as test names, so it's good if
             // they're valid identifiers.
             let name = name.chars().enumerate().map(|(i, c)| {
-                    if (i == 0 && c.is_xid_start()) ||
-                        (i != 0 && c.is_xid_continue()) {
+                    if (i == 0 && rustc_lexer::is_id_start(c)) ||
+                        (i != 0 && rustc_lexer::is_id_continue(c)) {
                         c
                     } else {
                         '_'
diff --git a/src/libstd/sys/sgx/condvar.rs b/src/libstd/sys/sgx/condvar.rs
index 000bb19f2692a..cc1c04a83e752 100644
--- a/src/libstd/sys/sgx/condvar.rs
+++ b/src/libstd/sys/sgx/condvar.rs
@@ -27,8 +27,7 @@ impl Condvar {
 
     pub unsafe fn wait(&self, mutex: &Mutex) {
         let guard = self.inner.lock();
-        mutex.unlock();
-        WaitQueue::wait(guard);
+        WaitQueue::wait(guard, || mutex.unlock());
         mutex.lock()
     }
 
diff --git a/src/libstd/sys/sgx/mutex.rs b/src/libstd/sys/sgx/mutex.rs
index f325fb1dd582f..662da8b3f6685 100644
--- a/src/libstd/sys/sgx/mutex.rs
+++ b/src/libstd/sys/sgx/mutex.rs
@@ -22,7 +22,7 @@ impl Mutex {
         let mut guard = self.inner.lock();
         if *guard.lock_var() {
             // Another thread has the lock, wait
-            WaitQueue::wait(guard)
+            WaitQueue::wait(guard, ||{})
             // Another thread has passed the lock to us
         } else {
             // We are just now obtaining the lock
@@ -83,7 +83,7 @@ impl ReentrantMutex {
         match guard.lock_var().owner {
             Some(tcs) if tcs != thread::current() => {
                 // Another thread has the lock, wait
-                WaitQueue::wait(guard);
+                WaitQueue::wait(guard, ||{});
                 // Another thread has passed the lock to us
             },
             _ => {
diff --git a/src/libstd/sys/sgx/rwlock.rs b/src/libstd/sys/sgx/rwlock.rs
index 30c47e44eef8e..e2f94b1d928e1 100644
--- a/src/libstd/sys/sgx/rwlock.rs
+++ b/src/libstd/sys/sgx/rwlock.rs
@@ -31,7 +31,7 @@ impl RWLock {
         if *wguard.lock_var() || !wguard.queue_empty() {
             // Another thread has or is waiting for the write lock, wait
             drop(wguard);
-            WaitQueue::wait(rguard);
+            WaitQueue::wait(rguard, ||{});
             // Another thread has passed the lock to us
         } else {
             // No waiting writers, acquire the read lock
@@ -62,7 +62,7 @@ impl RWLock {
         if *wguard.lock_var() || rguard.lock_var().is_some() {
             // Another thread has the lock, wait
             drop(rguard);
-            WaitQueue::wait(wguard);
+            WaitQueue::wait(wguard, ||{});
             // Another thread has passed the lock to us
         } else {
             // We are just now obtaining the lock
@@ -97,6 +97,7 @@ impl RWLock {
             if let Ok(mut wguard) = WaitQueue::notify_one(wguard) {
                 // A writer was waiting, pass the lock
                 *wguard.lock_var_mut() = true;
+                wguard.drop_after(rguard);
             } else {
                 // No writers were waiting, the lock is released
                 rtassert!(rguard.queue_empty());
@@ -117,21 +118,26 @@ impl RWLock {
         rguard: SpinMutexGuard<'_, WaitVariable<Option<NonZeroUsize>>>,
         wguard: SpinMutexGuard<'_, WaitVariable<bool>>,
     ) {
-        if let Err(mut wguard) = WaitQueue::notify_one(wguard) {
-            // No writers waiting, release the write lock
-            *wguard.lock_var_mut() = false;
-            if let Ok(mut rguard) = WaitQueue::notify_all(rguard) {
-                // One or more readers were waiting, pass the lock to them
-                if let NotifiedTcs::All { count } = rguard.notified_tcs() {
-                    *rguard.lock_var_mut() = Some(count)
+        match WaitQueue::notify_one(wguard) {
+            Err(mut wguard) => {
+                // No writers waiting, release the write lock
+                *wguard.lock_var_mut() = false;
+                if let Ok(mut rguard) = WaitQueue::notify_all(rguard) {
+                    // One or more readers were waiting, pass the lock to them
+                    if let NotifiedTcs::All { count } = rguard.notified_tcs() {
+                        *rguard.lock_var_mut() = Some(count)
+                    } else {
+                        unreachable!() // called notify_all
+                    }
+                    rguard.drop_after(wguard);
                 } else {
-                    unreachable!() // called notify_all
+                    // No readers waiting, the lock is released
                 }
-            } else {
-                // No readers waiting, the lock is released
+            },
+            Ok(wguard) => {
+                // There was a thread waiting for write, just pass the lock
+                wguard.drop_after(rguard);
             }
-        } else {
-            // There was a thread waiting for write, just pass the lock
         }
     }
 
diff --git a/src/libstd/sys/sgx/waitqueue.rs b/src/libstd/sys/sgx/waitqueue.rs
index d542f9b410127..3cb40e509b6b2 100644
--- a/src/libstd/sys/sgx/waitqueue.rs
+++ b/src/libstd/sys/sgx/waitqueue.rs
@@ -98,6 +98,12 @@ impl<'a, T> WaitGuard<'a, T> {
     pub fn notified_tcs(&self) -> NotifiedTcs {
         self.notified_tcs
     }
+
+    /// Drop this `WaitGuard`, after dropping another `guard`.
+    pub fn drop_after<U>(self, guard: U) {
+        drop(guard);
+        drop(self);
+    }
 }
 
 impl<'a, T> Deref for WaitGuard<'a, T> {
@@ -140,7 +146,7 @@ impl WaitQueue {
     /// until a wakeup event.
     ///
     /// This function does not return until this thread has been awoken.
-    pub fn wait<T>(mut guard: SpinMutexGuard<'_, WaitVariable<T>>) {
+    pub fn wait<T, F: FnOnce()>(mut guard: SpinMutexGuard<'_, WaitVariable<T>>, before_wait: F) {
         // very unsafe: check requirements of UnsafeList::push
         unsafe {
             let mut entry = UnsafeListEntry::new(SpinMutex::new(WaitEntry {
@@ -149,6 +155,7 @@ impl WaitQueue {
             }));
             let entry = guard.queue.inner.push(&mut entry);
             drop(guard);
+            before_wait();
             while !entry.lock().wake {
                 // don't panic, this would invalidate `entry` during unwinding
                 let eventset = rtunwrap!(Ok, usercalls::wait(EV_UNPARK, WAIT_INDEFINITE));
@@ -545,7 +552,7 @@ mod tests {
             assert!(WaitQueue::notify_one(wq2.lock()).is_ok());
         });
 
-        WaitQueue::wait(locked);
+        WaitQueue::wait(locked, ||{});
 
         t1.join().unwrap();
     }
diff --git a/src/libstd/sys/unix/process/process_common.rs b/src/libstd/sys/unix/process/process_common.rs
index 21fca23a8fe9e..a4ddd1ce6edc7 100644
--- a/src/libstd/sys/unix/process/process_common.rs
+++ b/src/libstd/sys/unix/process/process_common.rs
@@ -1,19 +1,27 @@
 use crate::os::unix::prelude::*;
 
-use crate::ffi::{OsString, OsStr, CString, CStr};
+use crate::ffi::{OsString, OsStr, CString};
 use crate::fmt;
 use crate::io;
 use crate::ptr;
 use crate::sys::fd::FileDesc;
-use crate::sys::fs::{File, OpenOptions};
+use crate::sys::fs::File;
 use crate::sys::pipe::{self, AnonPipe};
 use crate::sys_common::process::{CommandEnv, DefaultEnvKey};
 use crate::collections::BTreeMap;
 
+#[cfg(not(target_os = "fuchsia"))]
+use {
+    crate::ffi::CStr,
+    crate::sys::fs::OpenOptions,
+};
+
 use libc::{c_int, gid_t, uid_t, c_char, EXIT_SUCCESS, EXIT_FAILURE};
 
 cfg_if::cfg_if! {
-    if #[cfg(target_os = "redox")] {
+    if #[cfg(target_os = "fuchsia")] {
+        // fuchsia doesn't have /dev/null
+    } else if #[cfg(target_os = "redox")] {
         const DEV_NULL: &'static str = "null:\0";
     } else {
         const DEV_NULL: &'static str = "/dev/null\0";
@@ -107,6 +115,11 @@ pub enum ChildStdio {
     Inherit,
     Explicit(c_int),
     Owned(FileDesc),
+
+    // On Fuchsia, null stdio is the default, so we simply don't specify
+    // any actions at the time of spawning.
+    #[cfg(target_os = "fuchsia")]
+    Null,
 }
 
 pub enum Stdio {
@@ -325,6 +338,7 @@ impl Stdio {
                 Ok((ChildStdio::Owned(theirs.into_fd()), Some(ours)))
             }
 
+            #[cfg(not(target_os = "fuchsia"))]
             Stdio::Null => {
                 let mut opts = OpenOptions::new();
                 opts.read(readable);
@@ -335,6 +349,11 @@ impl Stdio {
                 let fd = File::open_c(&path, &opts)?;
                 Ok((ChildStdio::Owned(fd.into_fd()), None))
             }
+
+            #[cfg(target_os = "fuchsia")]
+            Stdio::Null => {
+                Ok((ChildStdio::Null, None))
+            }
         }
     }
 }
@@ -357,6 +376,9 @@ impl ChildStdio {
             ChildStdio::Inherit => None,
             ChildStdio::Explicit(fd) => Some(fd),
             ChildStdio::Owned(ref fd) => Some(fd.raw()),
+
+            #[cfg(target_os = "fuchsia")]
+            ChildStdio::Null => None,
         }
     }
 }
diff --git a/src/libstd/sys/unix/process/process_fuchsia.rs b/src/libstd/sys/unix/process/process_fuchsia.rs
index 7c6be9b0a6047..fff9fc6b3bbc8 100644
--- a/src/libstd/sys/unix/process/process_fuchsia.rs
+++ b/src/libstd/sys/unix/process/process_fuchsia.rs
@@ -48,30 +48,51 @@ impl Command {
         use crate::sys::process::zircon::*;
 
         let envp = match maybe_envp {
-            Some(envp) => envp.as_ptr(),
+            // None means to clone the current environment, which is done in the
+            // flags below.
             None => ptr::null(),
+            Some(envp) => envp.as_ptr(),
         };
 
-        let transfer_or_clone = |opt_fd, target_fd| if let Some(local_fd) = opt_fd {
-            fdio_spawn_action_t {
-                action: FDIO_SPAWN_ACTION_TRANSFER_FD,
-                local_fd,
-                target_fd,
-                ..Default::default()
-            }
-        } else {
-            fdio_spawn_action_t {
-                action: FDIO_SPAWN_ACTION_CLONE_FD,
-                local_fd: target_fd,
-                target_fd,
-                ..Default::default()
+        let make_action = |local_io: &ChildStdio, target_fd| -> io::Result<fdio_spawn_action_t> {
+            if let Some(local_fd) = local_io.fd() {
+                Ok(fdio_spawn_action_t {
+                    action: FDIO_SPAWN_ACTION_TRANSFER_FD,
+                    local_fd,
+                    target_fd,
+                    ..Default::default()
+                })
+            } else {
+                if let ChildStdio::Null = local_io {
+                    // acts as no-op
+                    return Ok(Default::default());
+                }
+
+                let mut handle = ZX_HANDLE_INVALID;
+                let status = fdio_fd_clone(target_fd, &mut handle);
+                if status == ERR_INVALID_ARGS || status == ERR_NOT_SUPPORTED {
+                    // This descriptor is closed; skip it rather than generating an
+                    // error.
+                    return Ok(Default::default());
+                }
+                zx_cvt(status)?;
+
+                let mut cloned_fd = 0;
+                zx_cvt(fdio_fd_create(handle, &mut cloned_fd))?;
+
+                Ok(fdio_spawn_action_t {
+                    action: FDIO_SPAWN_ACTION_TRANSFER_FD,
+                    local_fd: cloned_fd as i32,
+                    target_fd,
+                    ..Default::default()
+                })
             }
         };
 
         // Clone stdin, stdout, and stderr
-        let action1 = transfer_or_clone(stdio.stdin.fd(), 0);
-        let action2 = transfer_or_clone(stdio.stdout.fd(), 1);
-        let action3 = transfer_or_clone(stdio.stderr.fd(), 2);
+        let action1 = make_action(&stdio.stdin, 0)?;
+        let action2 = make_action(&stdio.stdout, 1)?;
+        let action3 = make_action(&stdio.stderr, 2)?;
         let actions = [action1, action2, action3];
 
         // We don't want FileDesc::drop to be called on any stdio. fdio_spawn_etc
@@ -84,9 +105,11 @@ impl Command {
 
         let mut process_handle: zx_handle_t = 0;
         zx_cvt(fdio_spawn_etc(
-            0,
-            FDIO_SPAWN_CLONE_JOB | FDIO_SPAWN_CLONE_LDSVC | FDIO_SPAWN_CLONE_NAMESPACE,
-            self.get_argv()[0], self.get_argv().as_ptr(), envp, 3, actions.as_ptr(),
+            ZX_HANDLE_INVALID,
+            FDIO_SPAWN_CLONE_JOB | FDIO_SPAWN_CLONE_LDSVC | FDIO_SPAWN_CLONE_NAMESPACE
+            | FDIO_SPAWN_CLONE_ENVIRON,  // this is ignored when envp is non-null
+            self.get_argv()[0], self.get_argv().as_ptr(), envp,
+            actions.len() as size_t, actions.as_ptr(),
             &mut process_handle,
             ptr::null_mut(),
         ))?;
diff --git a/src/libstd/sys/unix/process/zircon.rs b/src/libstd/sys/unix/process/zircon.rs
index ec715d5490f6f..1ba48de3c0785 100644
--- a/src/libstd/sys/unix/process/zircon.rs
+++ b/src/libstd/sys/unix/process/zircon.rs
@@ -2,8 +2,9 @@
 
 use crate::convert::TryInto;
 use crate::io;
+use crate::i64;
+use crate::mem::MaybeUninit;
 use crate::os::raw::c_char;
-use crate::u64;
 
 use libc::{c_int, c_void, size_t};
 
@@ -14,8 +15,8 @@ pub type zx_status_t = i32;
 
 pub const ZX_HANDLE_INVALID: zx_handle_t = 0;
 
-pub type zx_time_t = u64;
-pub const ZX_TIME_INFINITE : zx_time_t = u64::MAX;
+pub type zx_time_t = i64;
+pub const ZX_TIME_INFINITE : zx_time_t = i64::MAX;
 
 pub type zx_signals_t = u32;
 
@@ -120,8 +121,11 @@ pub struct fdio_spawn_action_t {
 extern {
     pub fn fdio_spawn_etc(job: zx_handle_t, flags: u32, path: *const c_char,
                           argv: *const *const c_char, envp: *const *const c_char,
-                          action_count: u64, actions: *const fdio_spawn_action_t,
+                          action_count: size_t, actions: *const fdio_spawn_action_t,
                           process: *mut zx_handle_t, err_msg: *mut c_char) -> zx_status_t;
+
+    pub fn fdio_fd_clone(fd: c_int, out_handle: *mut zx_handle_t) -> zx_status_t;
+    pub fn fdio_fd_create(handle: zx_handle_t, fd: *mut c_int) -> zx_status_t;
 }
 
 // fdio_spawn_etc flags
diff --git a/src/libsyntax/diagnostics/plugin.rs b/src/libsyntax/diagnostics/plugin.rs
index e9a55af52e878..5de39c8d14d17 100644
--- a/src/libsyntax/diagnostics/plugin.rs
+++ b/src/libsyntax/diagnostics/plugin.rs
@@ -6,7 +6,7 @@ use crate::ext::base::{ExtCtxt, MacEager, MacResult};
 use crate::parse::token::{self, Token};
 use crate::ptr::P;
 use crate::symbol::kw;
-use crate::tokenstream::{TokenTree};
+use crate::tokenstream::{TokenTree, TokenStream};
 
 use smallvec::smallvec;
 use syntax_pos::Span;
@@ -27,12 +27,11 @@ pub type ErrorMap = BTreeMap<Name, ErrorInfo>;
 
 pub fn expand_diagnostic_used<'cx>(ecx: &'cx mut ExtCtxt<'_>,
                                    span: Span,
-                                   token_tree: &[TokenTree])
+                                   tts: TokenStream)
                                    -> Box<dyn MacResult+'cx> {
-    let code = match token_tree {
-        [
-            TokenTree::Token(Token { kind: token::Ident(code, _), .. })
-        ] => code,
+    assert_eq!(tts.len(), 1);
+    let code = match tts.into_trees().next() {
+        Some(TokenTree::Token(Token { kind: token::Ident(code, _), .. })) => code,
         _ => unreachable!()
     };
 
@@ -62,20 +61,21 @@ pub fn expand_diagnostic_used<'cx>(ecx: &'cx mut ExtCtxt<'_>,
 
 pub fn expand_register_diagnostic<'cx>(ecx: &'cx mut ExtCtxt<'_>,
                                        span: Span,
-                                       token_tree: &[TokenTree])
+                                       tts: TokenStream)
                                        -> Box<dyn MacResult+'cx> {
-    let (code, description) = match  token_tree {
-        [
-            TokenTree::Token(Token { kind: token::Ident(code, _), .. })
-        ] => {
-            (*code, None)
-        },
-        [
-            TokenTree::Token(Token { kind: token::Ident(code, _), .. }),
-            TokenTree::Token(Token { kind: token::Comma, .. }),
-            TokenTree::Token(Token { kind: token::Literal(token::Lit { symbol, .. }), ..})
-        ] => {
-            (*code, Some(*symbol))
+    assert!(tts.len() == 1 || tts.len() == 3);
+    let mut cursor = tts.into_trees();
+    let code = match cursor.next() {
+        Some(TokenTree::Token(Token { kind: token::Ident(code, _), .. })) => code,
+        _ => unreachable!()
+    };
+    let description = match  (cursor.next(), cursor.next()) {
+        (None, None) => None,
+        (
+            Some(TokenTree::Token(Token { kind: token::Comma, .. })),
+            Some(TokenTree::Token(Token { kind: token::Literal(token::Lit { symbol, .. }), ..}))
+        ) => {
+            Some(symbol)
         },
         _ => unreachable!()
     };
@@ -121,12 +121,12 @@ pub fn expand_register_diagnostic<'cx>(ecx: &'cx mut ExtCtxt<'_>,
 
 pub fn expand_build_diagnostic_array<'cx>(ecx: &'cx mut ExtCtxt<'_>,
                                           span: Span,
-                                          token_tree: &[TokenTree])
+                                          tts: TokenStream)
                                           -> Box<dyn MacResult+'cx> {
-    assert_eq!(token_tree.len(), 3);
-    let ident = match &token_tree[2] {
+    assert_eq!(tts.len(), 3);
+    let ident = match tts.into_trees().nth(2) {
         // DIAGNOSTICS ident.
-        &TokenTree::Token(Token { kind: token::Ident(name, _), span })
+        Some(TokenTree::Token(Token { kind: token::Ident(name, _), span }))
         => Ident::new(name, span),
         _ => unreachable!()
     };
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 5d68983d7cb66..109ba041016c6 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -10,7 +10,7 @@ use crate::parse::token;
 use crate::ptr::P;
 use crate::symbol::{kw, sym, Ident, Symbol};
 use crate::{ThinVec, MACRO_ARGUMENTS};
-use crate::tokenstream::{self, TokenStream, TokenTree};
+use crate::tokenstream::{self, TokenStream};
 use crate::visit::Visitor;
 
 use errors::{DiagnosticBuilder, DiagnosticId};
@@ -235,18 +235,18 @@ pub trait TTMacroExpander {
 }
 
 pub type MacroExpanderFn =
-    for<'cx> fn(&'cx mut ExtCtxt<'_>, Span, &[tokenstream::TokenTree])
+    for<'cx> fn(&'cx mut ExtCtxt<'_>, Span, TokenStream)
                 -> Box<dyn MacResult+'cx>;
 
 impl<F> TTMacroExpander for F
-    where F: for<'cx> Fn(&'cx mut ExtCtxt<'_>, Span, &[tokenstream::TokenTree])
+    where F: for<'cx> Fn(&'cx mut ExtCtxt<'_>, Span, TokenStream)
     -> Box<dyn MacResult+'cx>
 {
     fn expand<'cx>(
         &self,
         ecx: &'cx mut ExtCtxt<'_>,
         span: Span,
-        input: TokenStream,
+        mut input: TokenStream,
     ) -> Box<dyn MacResult+'cx> {
         struct AvoidInterpolatedIdents;
 
@@ -268,10 +268,8 @@ impl<F> TTMacroExpander for F
                 mut_visit::noop_visit_mac(mac, self)
             }
         }
-
-        let input: Vec<_> =
-            input.trees().map(|mut tt| { AvoidInterpolatedIdents.visit_tt(&mut tt); tt }).collect();
-        (*self)(ecx, span, &input)
+        AvoidInterpolatedIdents.visit_tts(&mut input);
+        (*self)(ecx, span, input)
     }
 }
 
@@ -677,7 +675,7 @@ impl SyntaxExtension {
     }
 
     pub fn dummy_bang(edition: Edition) -> SyntaxExtension {
-        fn expander<'cx>(_: &'cx mut ExtCtxt<'_>, span: Span, _: &[TokenTree])
+        fn expander<'cx>(_: &'cx mut ExtCtxt<'_>, span: Span, _: TokenStream)
                          -> Box<dyn MacResult + 'cx> {
             DummyResult::any(span)
         }
@@ -811,9 +809,8 @@ impl<'a> ExtCtxt<'a> {
     pub fn monotonic_expander<'b>(&'b mut self) -> expand::MacroExpander<'b, 'a> {
         expand::MacroExpander::new(self, true)
     }
-
-    pub fn new_parser_from_tts(&self, tts: &[tokenstream::TokenTree]) -> parser::Parser<'a> {
-        parse::stream_to_parser(self.parse_sess, tts.iter().cloned().collect(), MACRO_ARGUMENTS)
+    pub fn new_parser_from_tts(&self, stream: TokenStream) -> parser::Parser<'a> {
+        parse::stream_to_parser(self.parse_sess, stream, MACRO_ARGUMENTS)
     }
     pub fn source_map(&self) -> &'a SourceMap { self.parse_sess.source_map() }
     pub fn parse_sess(&self) -> &'a parse::ParseSess { self.parse_sess }
@@ -1019,7 +1016,7 @@ pub fn expr_to_string(cx: &mut ExtCtxt<'_>, expr: P<ast::Expr>, err_msg: &str)
 /// done as rarely as possible).
 pub fn check_zero_tts(cx: &ExtCtxt<'_>,
                       sp: Span,
-                      tts: &[tokenstream::TokenTree],
+                      tts: TokenStream,
                       name: &str) {
     if !tts.is_empty() {
         cx.span_err(sp, &format!("{} takes no arguments", name));
@@ -1030,7 +1027,7 @@ pub fn check_zero_tts(cx: &ExtCtxt<'_>,
 /// expect exactly one string literal, or emit an error and return `None`.
 pub fn get_single_str_from_tts(cx: &mut ExtCtxt<'_>,
                                sp: Span,
-                               tts: &[tokenstream::TokenTree],
+                               tts: TokenStream,
                                name: &str)
                                -> Option<String> {
     let mut p = cx.new_parser_from_tts(tts);
@@ -1053,7 +1050,7 @@ pub fn get_single_str_from_tts(cx: &mut ExtCtxt<'_>,
 /// parsing error, emit a non-fatal error and return `None`.
 pub fn get_exprs_from_tts(cx: &mut ExtCtxt<'_>,
                           sp: Span,
-                          tts: &[tokenstream::TokenTree]) -> Option<Vec<P<ast::Expr>>> {
+                          tts: TokenStream) -> Option<Vec<P<ast::Expr>>> {
     let mut p = cx.new_parser_from_tts(tts);
     let mut es = Vec::new();
     while p.token != token::Eof {
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 7b4a516744642..4fd0c367288bf 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -701,7 +701,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         path: &Path,
         span: Span,
     ) -> AstFragment {
-        let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
+        let mut parser = self.cx.new_parser_from_tts(toks);
         match parser.parse_ast_fragment(kind, false) {
             Ok(fragment) => {
                 parser.ensure_complete_parse(path, kind.name(), span);
diff --git a/src/libsyntax/ext/proc_macro_server.rs b/src/libsyntax/ext/proc_macro_server.rs
index 1a26b17dac782..544ec789d80a9 100644
--- a/src/libsyntax/ext/proc_macro_server.rs
+++ b/src/libsyntax/ext/proc_macro_server.rs
@@ -322,8 +322,7 @@ impl Ident {
     fn is_valid(string: &str) -> bool {
         let mut chars = string.chars();
         if let Some(start) = chars.next() {
-            (start == '_' || start.is_xid_start())
-                && chars.all(|cont| cont == '_' || cont.is_xid_continue())
+            rustc_lexer::is_id_start(start) && chars.all(rustc_lexer::is_id_continue)
         } else {
             false
         }
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index bead941b20d5a..37305055e62a3 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -356,11 +356,7 @@ pub fn tt_to_string(tt: tokenstream::TokenTree) -> String {
     to_string(|s| s.print_tt(tt, false))
 }
 
-pub fn tts_to_string(tts: &[tokenstream::TokenTree]) -> String {
-    tokens_to_string(tts.iter().cloned().collect())
-}
-
-pub fn tokens_to_string(tokens: TokenStream) -> String {
+pub fn tts_to_string(tokens: TokenStream) -> String {
     to_string(|s| s.print_tts(tokens, false))
 }
 
diff --git a/src/libsyntax/tests.rs b/src/libsyntax/tests.rs
index c472212bc2096..9b90b31f2d2a2 100644
--- a/src/libsyntax/tests.rs
+++ b/src/libsyntax/tests.rs
@@ -63,7 +63,7 @@ crate fn matches_codepattern(a : &str, b : &str) -> bool {
             (None, None) => return true,
             (None, _) => return false,
             (Some(&a), None) => {
-                if is_pattern_whitespace(a) {
+                if rustc_lexer::is_whitespace(a) {
                     break // trailing whitespace check is out of loop for borrowck
                 } else {
                     return false
@@ -72,11 +72,11 @@ crate fn matches_codepattern(a : &str, b : &str) -> bool {
             (Some(&a), Some(&b)) => (a, b)
         };
 
-        if is_pattern_whitespace(a) && is_pattern_whitespace(b) {
+        if rustc_lexer::is_whitespace(a) && rustc_lexer::is_whitespace(b) {
             // skip whitespace for a and b
             scan_for_non_ws_or_end(&mut a_iter);
             scan_for_non_ws_or_end(&mut b_iter);
-        } else if is_pattern_whitespace(a) {
+        } else if rustc_lexer::is_whitespace(a) {
             // skip whitespace for a
             scan_for_non_ws_or_end(&mut a_iter);
         } else if a == b {
@@ -88,20 +88,16 @@ crate fn matches_codepattern(a : &str, b : &str) -> bool {
     }
 
     // check if a has *only* trailing whitespace
-    a_iter.all(is_pattern_whitespace)
+    a_iter.all(rustc_lexer::is_whitespace)
 }
 
 /// Advances the given peekable `Iterator` until it reaches a non-whitespace character
 fn scan_for_non_ws_or_end<I: Iterator<Item = char>>(iter: &mut Peekable<I>) {
-    while iter.peek().copied().map(|c| is_pattern_whitespace(c)) == Some(true) {
+    while iter.peek().copied().map(|c| rustc_lexer::is_whitespace(c)) == Some(true) {
         iter.next();
     }
 }
 
-fn is_pattern_whitespace(c: char) -> bool {
-    rustc_lexer::character_properties::is_whitespace(c)
-}
-
 /// Identify a position in the text by the Nth occurrence of a string.
 struct Position {
     string: &'static str,
diff --git a/src/libsyntax/tokenstream.rs b/src/libsyntax/tokenstream.rs
index 0d9f3769ce904..480553586197e 100644
--- a/src/libsyntax/tokenstream.rs
+++ b/src/libsyntax/tokenstream.rs
@@ -506,7 +506,7 @@ impl Cursor {
 
 impl fmt::Display for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(&pprust::tokens_to_string(self.clone()))
+        f.write_str(&pprust::tts_to_string(self.clone()))
     }
 }
 
diff --git a/src/libsyntax_ext/Cargo.toml b/src/libsyntax_ext/Cargo.toml
index 73310df305b32..791ee94b4fa77 100644
--- a/src/libsyntax_ext/Cargo.toml
+++ b/src/libsyntax_ext/Cargo.toml
@@ -18,3 +18,4 @@ rustc_target = { path = "../librustc_target" }
 smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
+rustc_lexer = { path = "../librustc_lexer" }
diff --git a/src/libsyntax_ext/asm.rs b/src/libsyntax_ext/asm.rs
index 28f907441d872..328b307361d9e 100644
--- a/src/libsyntax_ext/asm.rs
+++ b/src/libsyntax_ext/asm.rs
@@ -8,13 +8,12 @@ use errors::DiagnosticBuilder;
 
 use syntax::ast;
 use syntax::ext::base::{self, *};
-use syntax::parse;
 use syntax::parse::token::{self, Token};
 use syntax::ptr::P;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::ast::AsmDialect;
 use syntax_pos::Span;
-use syntax::tokenstream;
+use syntax::tokenstream::{self, TokenStream};
 use syntax::{span_err, struct_span_err};
 
 enum State {
@@ -43,7 +42,7 @@ const OPTIONS: &[Symbol] = &[sym::volatile, sym::alignstack, sym::intel];
 
 pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt<'_>,
                        sp: Span,
-                       tts: &[tokenstream::TokenTree])
+                       tts: TokenStream)
                        -> Box<dyn base::MacResult + 'cx> {
     let mut inline_asm = match parse_inline_asm(cx, sp, tts) {
         Ok(Some(inline_asm)) => inline_asm,
@@ -71,20 +70,20 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt<'_>,
 fn parse_inline_asm<'a>(
     cx: &mut ExtCtxt<'a>,
     sp: Span,
-    tts: &[tokenstream::TokenTree],
+    tts: TokenStream,
 ) -> Result<Option<ast::InlineAsm>, DiagnosticBuilder<'a>> {
     // Split the tts before the first colon, to avoid `asm!("x": y)`  being
     // parsed as `asm!(z)` with `z = "x": y` which is type ascription.
-    let first_colon = tts.iter()
+    let first_colon = tts.trees()
         .position(|tt| {
-            match *tt {
+            match tt {
                 tokenstream::TokenTree::Token(Token { kind: token::Colon, .. }) |
                 tokenstream::TokenTree::Token(Token { kind: token::ModSep, .. }) => true,
                 _ => false,
             }
         })
         .unwrap_or(tts.len());
-    let mut p = cx.new_parser_from_tts(&tts[first_colon..]);
+    let mut p = cx.new_parser_from_tts(tts.trees().skip(first_colon).collect());
     let mut asm = kw::Invalid;
     let mut asm_str_style = None;
     let mut outputs = Vec::new();
@@ -110,7 +109,8 @@ fn parse_inline_asm<'a>(
                     ));
                 }
                 // Nested parser, stop before the first colon (see above).
-                let mut p2 = cx.new_parser_from_tts(&tts[..first_colon]);
+                let mut p2 =
+                    cx.new_parser_from_tts(tts.trees().take(first_colon).collect());
 
                 if p2.token == token::Eof {
                     let mut err =
@@ -129,12 +129,8 @@ fn parse_inline_asm<'a>(
                 // This is most likely malformed.
                 if p2.token != token::Eof {
                     let mut extra_tts = p2.parse_all_token_trees()?;
-                    extra_tts.extend(tts[first_colon..].iter().cloned());
-                    p = parse::stream_to_parser(
-                        cx.parse_sess,
-                        extra_tts.into_iter().collect(),
-                        Some("inline assembly"),
-                    );
+                    extra_tts.extend(tts.trees().skip(first_colon));
+                    p = cx.new_parser_from_tts(extra_tts.into_iter().collect());
                 }
 
                 asm = s;
diff --git a/src/libsyntax_ext/assert.rs b/src/libsyntax_ext/assert.rs
index 84583d0e5eca7..001996e1db718 100644
--- a/src/libsyntax_ext/assert.rs
+++ b/src/libsyntax_ext/assert.rs
@@ -13,7 +13,7 @@ use syntax_pos::{Span, DUMMY_SP};
 pub fn expand_assert<'cx>(
     cx: &'cx mut ExtCtxt<'_>,
     sp: Span,
-    tts: &[TokenTree],
+    tts: TokenStream,
 ) -> Box<dyn MacResult + 'cx> {
     let Assert { cond_expr, custom_message } = match parse_assert(cx, sp, tts) {
         Ok(assert) => assert,
@@ -59,9 +59,9 @@ struct Assert {
 fn parse_assert<'a>(
     cx: &mut ExtCtxt<'a>,
     sp: Span,
-    tts: &[TokenTree]
+    stream: TokenStream
 ) -> Result<Assert, DiagnosticBuilder<'a>> {
-    let mut parser = cx.new_parser_from_tts(tts);
+    let mut parser = cx.new_parser_from_tts(stream);
 
     if parser.token == token::Eof {
         let mut err = cx.struct_span_err(sp, "macro requires a boolean expression as an argument");
diff --git a/src/libsyntax_ext/cfg.rs b/src/libsyntax_ext/cfg.rs
index 21cee8ae1cb9c..0342e442df2e9 100644
--- a/src/libsyntax_ext/cfg.rs
+++ b/src/libsyntax_ext/cfg.rs
@@ -7,14 +7,14 @@ use errors::DiagnosticBuilder;
 use syntax::ast;
 use syntax::ext::base::{self, *};
 use syntax::attr;
-use syntax::tokenstream;
+use syntax::tokenstream::TokenStream;
 use syntax::parse::token;
 use syntax_pos::Span;
 
 pub fn expand_cfg(
     cx: &mut ExtCtxt<'_>,
     sp: Span,
-    tts: &[tokenstream::TokenTree],
+    tts: TokenStream,
 ) -> Box<dyn base::MacResult + 'static> {
     let sp = cx.with_legacy_ctxt(sp);
 
@@ -33,7 +33,7 @@ pub fn expand_cfg(
 fn parse_cfg<'a>(
     cx: &mut ExtCtxt<'a>,
     sp: Span,
-    tts: &[tokenstream::TokenTree],
+    tts: TokenStream,
 ) -> Result<ast::MetaItem, DiagnosticBuilder<'a>> {
     let mut p = cx.new_parser_from_tts(tts);
 
diff --git a/src/libsyntax_ext/compile_error.rs b/src/libsyntax_ext/compile_error.rs
index 59d3f2c9c7813..24f3a66d4ae19 100644
--- a/src/libsyntax_ext/compile_error.rs
+++ b/src/libsyntax_ext/compile_error.rs
@@ -2,11 +2,11 @@
 
 use syntax::ext::base::{self, *};
 use syntax_pos::Span;
-use syntax::tokenstream;
+use syntax::tokenstream::TokenStream;
 
 pub fn expand_compile_error<'cx>(cx: &'cx mut ExtCtxt<'_>,
                               sp: Span,
-                              tts: &[tokenstream::TokenTree])
+                              tts: TokenStream)
                               -> Box<dyn base::MacResult + 'cx> {
     let var = match get_single_str_from_tts(cx, sp, tts, "compile_error!") {
         None => return DummyResult::any(sp),
diff --git a/src/libsyntax_ext/concat.rs b/src/libsyntax_ext/concat.rs
index ffa5154ca0c36..fc56dff65e4e2 100644
--- a/src/libsyntax_ext/concat.rs
+++ b/src/libsyntax_ext/concat.rs
@@ -1,14 +1,14 @@
 use syntax::ast;
 use syntax::ext::base::{self, DummyResult};
 use syntax::symbol::Symbol;
-use syntax::tokenstream;
+use syntax::tokenstream::TokenStream;
 
 use std::string::String;
 
-pub fn expand_syntax_ext(
+pub fn expand_concat(
     cx: &mut base::ExtCtxt<'_>,
     sp: syntax_pos::Span,
-    tts: &[tokenstream::TokenTree],
+    tts: TokenStream,
 ) -> Box<dyn base::MacResult + 'static> {
     let es = match base::get_exprs_from_tts(cx, sp, tts) {
         Some(e) => e,
diff --git a/src/libsyntax_ext/concat_idents.rs b/src/libsyntax_ext/concat_idents.rs
index 96677072d1b80..6391b62b58dc9 100644
--- a/src/libsyntax_ext/concat_idents.rs
+++ b/src/libsyntax_ext/concat_idents.rs
@@ -6,21 +6,21 @@ use syntax::parse::token::{self, Token};
 use syntax::ptr::P;
 use syntax_pos::Span;
 use syntax_pos::symbol::Symbol;
-use syntax::tokenstream::TokenTree;
+use syntax::tokenstream::{TokenTree, TokenStream};
 
-pub fn expand_syntax_ext<'cx>(cx: &'cx mut ExtCtxt<'_>,
-                              sp: Span,
-                              tts: &[TokenTree])
-                              -> Box<dyn base::MacResult + 'cx> {
+pub fn expand_concat_idents<'cx>(cx: &'cx mut ExtCtxt<'_>,
+                                 sp: Span,
+                                 tts: TokenStream)
+                                 -> Box<dyn base::MacResult + 'cx> {
     if tts.is_empty() {
         cx.span_err(sp, "concat_idents! takes 1 or more arguments.");
         return DummyResult::any(sp);
     }
 
     let mut res_str = String::new();
-    for (i, e) in tts.iter().enumerate() {
+    for (i, e) in tts.into_trees().enumerate() {
         if i & 1 == 1 {
-            match *e {
+            match e {
                 TokenTree::Token(Token { kind: token::Comma, .. }) => {}
                 _ => {
                     cx.span_err(sp, "concat_idents! expecting comma.");
@@ -28,7 +28,7 @@ pub fn expand_syntax_ext<'cx>(cx: &'cx mut ExtCtxt<'_>,
                 }
             }
         } else {
-            match *e {
+            match e {
                 TokenTree::Token(Token { kind: token::Ident(name, _), .. }) =>
                     res_str.push_str(&name.as_str()),
                 _ => {
diff --git a/src/libsyntax_ext/env.rs b/src/libsyntax_ext/env.rs
index 6343d218de829..179b7fe00a97a 100644
--- a/src/libsyntax_ext/env.rs
+++ b/src/libsyntax_ext/env.rs
@@ -7,13 +7,13 @@ use syntax::ast::{self, Ident, GenericArg};
 use syntax::ext::base::{self, *};
 use syntax::symbol::{kw, sym, Symbol};
 use syntax_pos::Span;
-use syntax::tokenstream;
+use syntax::tokenstream::TokenStream;
 
 use std::env;
 
 pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
                               sp: Span,
-                              tts: &[tokenstream::TokenTree])
+                              tts: TokenStream)
                               -> Box<dyn base::MacResult + 'cx> {
     let var = match get_single_str_from_tts(cx, sp, tts, "option_env!") {
         None => return DummyResult::any(sp),
@@ -45,7 +45,7 @@ pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
 
 pub fn expand_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
                        sp: Span,
-                       tts: &[tokenstream::TokenTree])
+                       tts: TokenStream)
                        -> Box<dyn base::MacResult + 'cx> {
     let mut exprs = match get_exprs_from_tts(cx, sp, tts) {
         Some(ref exprs) if exprs.is_empty() => {
diff --git a/src/libsyntax_ext/format.rs b/src/libsyntax_ext/format.rs
index 47394c02b4186..ad275f421af49 100644
--- a/src/libsyntax_ext/format.rs
+++ b/src/libsyntax_ext/format.rs
@@ -11,7 +11,7 @@ use syntax::ext::base::{self, *};
 use syntax::parse::token;
 use syntax::ptr::P;
 use syntax::symbol::{Symbol, sym};
-use syntax::tokenstream;
+use syntax::tokenstream::TokenStream;
 use syntax_pos::{MultiSpan, Span};
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
@@ -126,7 +126,7 @@ struct Context<'a, 'b> {
 fn parse_args<'a>(
     ecx: &mut ExtCtxt<'a>,
     sp: Span,
-    tts: &[tokenstream::TokenTree]
+    tts: TokenStream,
 ) -> Result<(P<ast::Expr>, Vec<P<ast::Expr>>, FxHashMap<Symbol, usize>), DiagnosticBuilder<'a>> {
     let mut args = Vec::<P<ast::Expr>>::new();
     let mut names = FxHashMap::<Symbol, usize>::default();
@@ -794,7 +794,7 @@ impl<'a, 'b> Context<'a, 'b> {
 fn expand_format_args_impl<'cx>(
     ecx: &'cx mut ExtCtxt<'_>,
     mut sp: Span,
-    tts: &[tokenstream::TokenTree],
+    tts: TokenStream,
     nl: bool,
 ) -> Box<dyn base::MacResult + 'cx> {
     sp = ecx.with_def_site_ctxt(sp);
@@ -812,7 +812,7 @@ fn expand_format_args_impl<'cx>(
 pub fn expand_format_args<'cx>(
     ecx: &'cx mut ExtCtxt<'_>,
     sp: Span,
-    tts: &[tokenstream::TokenTree],
+    tts: TokenStream,
 ) -> Box<dyn base::MacResult + 'cx> {
     expand_format_args_impl(ecx, sp, tts, false)
 }
@@ -820,7 +820,7 @@ pub fn expand_format_args<'cx>(
 pub fn expand_format_args_nl<'cx>(
     ecx: &'cx mut ExtCtxt<'_>,
     sp: Span,
-    tts: &[tokenstream::TokenTree],
+    tts: TokenStream,
 ) -> Box<dyn base::MacResult + 'cx> {
     expand_format_args_impl(ecx, sp, tts, true)
 }
diff --git a/src/libsyntax_ext/global_asm.rs b/src/libsyntax_ext/global_asm.rs
index a8b61593db749..6140f0df58af9 100644
--- a/src/libsyntax_ext/global_asm.rs
+++ b/src/libsyntax_ext/global_asm.rs
@@ -16,12 +16,12 @@ use syntax::ext::base::{self, *};
 use syntax::parse::token;
 use syntax::ptr::P;
 use syntax_pos::Span;
-use syntax::tokenstream;
+use syntax::tokenstream::TokenStream;
 use smallvec::smallvec;
 
 pub fn expand_global_asm<'cx>(cx: &'cx mut ExtCtxt<'_>,
                               sp: Span,
-                              tts: &[tokenstream::TokenTree]) -> Box<dyn base::MacResult + 'cx> {
+                              tts: TokenStream) -> Box<dyn base::MacResult + 'cx> {
     match parse_global_asm(cx, sp, tts) {
         Ok(Some(global_asm)) => {
             MacEager::items(smallvec![P(ast::Item {
@@ -45,7 +45,7 @@ pub fn expand_global_asm<'cx>(cx: &'cx mut ExtCtxt<'_>,
 fn parse_global_asm<'a>(
     cx: &mut ExtCtxt<'a>,
     sp: Span,
-    tts: &[tokenstream::TokenTree]
+    tts: TokenStream
 ) -> Result<Option<ast::GlobalAsm>, DiagnosticBuilder<'a>> {
     let mut p = cx.new_parser_from_tts(tts);
 
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index 1a6176916623b..26ef80b2b06df 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -67,8 +67,8 @@ pub fn register_builtin_macros(resolver: &mut dyn syntax::ext::base::Resolver, e
         cfg: cfg::expand_cfg,
         column: source_util::expand_column,
         compile_error: compile_error::expand_compile_error,
-        concat_idents: concat_idents::expand_syntax_ext,
-        concat: concat::expand_syntax_ext,
+        concat_idents: concat_idents::expand_concat_idents,
+        concat: concat::expand_concat,
         env: env::expand_env,
         file: source_util::expand_file,
         format_args_nl: format::expand_format_args_nl,
@@ -78,7 +78,7 @@ pub fn register_builtin_macros(resolver: &mut dyn syntax::ext::base::Resolver, e
         include_str: source_util::expand_include_str,
         include: source_util::expand_include,
         line: source_util::expand_line,
-        log_syntax: log_syntax::expand_syntax_ext,
+        log_syntax: log_syntax::expand_log_syntax,
         module_path: source_util::expand_mod,
         option_env: env::expand_option_env,
         stringify: source_util::expand_stringify,
diff --git a/src/libsyntax_ext/log_syntax.rs b/src/libsyntax_ext/log_syntax.rs
index cbdfd08b4977f..92130bfaf68e3 100644
--- a/src/libsyntax_ext/log_syntax.rs
+++ b/src/libsyntax_ext/log_syntax.rs
@@ -1,11 +1,11 @@
 use syntax::ext::base;
 use syntax::print;
-use syntax::tokenstream;
+use syntax::tokenstream::TokenStream;
 use syntax_pos;
 
-pub fn expand_syntax_ext<'cx>(_cx: &'cx mut base::ExtCtxt<'_>,
+pub fn expand_log_syntax<'cx>(_cx: &'cx mut base::ExtCtxt<'_>,
                               sp: syntax_pos::Span,
-                              tts: &[tokenstream::TokenTree])
+                              tts: TokenStream)
                               -> Box<dyn base::MacResult + 'cx> {
     println!("{}", print::pprust::tts_to_string(tts));
 
diff --git a/src/libsyntax_ext/source_util.rs b/src/libsyntax_ext/source_util.rs
index e008ed710e4d0..9dc9d66b86f1d 100644
--- a/src/libsyntax_ext/source_util.rs
+++ b/src/libsyntax_ext/source_util.rs
@@ -4,7 +4,7 @@ use syntax::parse::{self, token, DirectoryOwnership};
 use syntax::print::pprust;
 use syntax::ptr::P;
 use syntax::symbol::Symbol;
-use syntax::tokenstream;
+use syntax::tokenstream::TokenStream;
 
 use smallvec::SmallVec;
 use syntax_pos::{self, Pos, Span};
@@ -16,7 +16,7 @@ use rustc_data_structures::sync::Lrc;
 // a given file into the current one.
 
 /// line!(): expands to the current line number
-pub fn expand_line(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
+pub fn expand_line(cx: &mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
                    -> Box<dyn base::MacResult+'static> {
     base::check_zero_tts(cx, sp, tts, "line!");
 
@@ -27,7 +27,7 @@ pub fn expand_line(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree
 }
 
 /* column!(): expands to the current column number */
-pub fn expand_column(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
+pub fn expand_column(cx: &mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
                   -> Box<dyn base::MacResult+'static> {
     base::check_zero_tts(cx, sp, tts, "column!");
 
@@ -40,7 +40,7 @@ pub fn expand_column(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTr
 /// file!(): expands to the current filename */
 /// The source_file (`loc.file`) contains a bunch more information we could spit
 /// out if we wanted.
-pub fn expand_file(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
+pub fn expand_file(cx: &mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
                    -> Box<dyn base::MacResult+'static> {
     base::check_zero_tts(cx, sp, tts, "file!");
 
@@ -49,13 +49,13 @@ pub fn expand_file(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree
     base::MacEager::expr(cx.expr_str(topmost, Symbol::intern(&loc.file.name.to_string())))
 }
 
-pub fn expand_stringify(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
+pub fn expand_stringify(cx: &mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
                         -> Box<dyn base::MacResult+'static> {
     let s = pprust::tts_to_string(tts);
     base::MacEager::expr(cx.expr_str(sp, Symbol::intern(&s)))
 }
 
-pub fn expand_mod(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
+pub fn expand_mod(cx: &mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
                   -> Box<dyn base::MacResult+'static> {
     base::check_zero_tts(cx, sp, tts, "module_path!");
     let mod_path = &cx.current_expansion.module.mod_path;
@@ -67,7 +67,7 @@ pub fn expand_mod(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree]
 /// include! : parse the given file as an expr
 /// This is generally a bad idea because it's going to behave
 /// unhygienically.
-pub fn expand_include<'cx>(cx: &'cx mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
+pub fn expand_include<'cx>(cx: &'cx mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
                            -> Box<dyn base::MacResult+'cx> {
     let file = match get_single_str_from_tts(cx, sp, tts, "include!") {
         Some(f) => f,
@@ -105,7 +105,7 @@ pub fn expand_include<'cx>(cx: &'cx mut ExtCtxt<'_>, sp: Span, tts: &[tokenstrea
 }
 
 // include_str! : read the given file, insert it as a literal string expr
-pub fn expand_include_str(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
+pub fn expand_include_str(cx: &mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
                           -> Box<dyn base::MacResult+'static> {
     let file = match get_single_str_from_tts(cx, sp, tts, "include_str!") {
         Some(f) => f,
@@ -130,7 +130,7 @@ pub fn expand_include_str(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::To
     }
 }
 
-pub fn expand_include_bytes(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
+pub fn expand_include_bytes(cx: &mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
                             -> Box<dyn base::MacResult+'static> {
     let file = match get_single_str_from_tts(cx, sp, tts, "include_bytes!") {
         Some(f) => f,
diff --git a/src/libsyntax_ext/trace_macros.rs b/src/libsyntax_ext/trace_macros.rs
index 0dce8a36f4c7b..d83c24046d9e5 100644
--- a/src/libsyntax_ext/trace_macros.rs
+++ b/src/libsyntax_ext/trace_macros.rs
@@ -1,20 +1,27 @@
 use syntax::ext::base::{self, ExtCtxt};
 use syntax::symbol::kw;
 use syntax_pos::Span;
-use syntax::tokenstream::TokenTree;
+use syntax::tokenstream::{TokenTree, TokenStream};
 
 pub fn expand_trace_macros(cx: &mut ExtCtxt<'_>,
                            sp: Span,
-                           tt: &[TokenTree])
+                           tt: TokenStream)
                            -> Box<dyn base::MacResult + 'static> {
-    match tt {
-        [TokenTree::Token(token)] if token.is_keyword(kw::True) => {
-            cx.set_trace_macros(true);
-        }
-        [TokenTree::Token(token)] if token.is_keyword(kw::False) => {
-            cx.set_trace_macros(false);
-        }
-        _ => cx.span_err(sp, "trace_macros! accepts only `true` or `false`"),
+    let mut cursor = tt.into_trees();
+    let mut err = false;
+    let value = match &cursor.next() {
+        Some(TokenTree::Token(token)) if token.is_keyword(kw::True) => true,
+        Some(TokenTree::Token(token)) if token.is_keyword(kw::False) => false,
+        _ => {
+            err = true;
+            false
+        },
+    };
+    err |= cursor.next().is_some();
+    if err {
+        cx.span_err(sp, "trace_macros! accepts only `true` or `false`")
+    } else {
+        cx.set_trace_macros(value);
     }
 
     base::DummyResult::any_valid(sp)
diff --git a/src/test/debuginfo/boxed-struct.rs b/src/test/debuginfo/boxed-struct.rs
index c0ff90c3ffb9b..8709fb681704b 100644
--- a/src/test/debuginfo/boxed-struct.rs
+++ b/src/test/debuginfo/boxed-struct.rs
@@ -8,11 +8,11 @@
 
 // gdb-command:run
 
-// gdb-command:print *unique
+// gdb-command:print *boxed_with_padding
 // gdbg-check:$1 = {x = 99, y = 999, z = 9999, w = 99999}
 // gdbr-check:$1 = boxed_struct::StructWithSomePadding {x: 99, y: 999, z: 9999, w: 99999}
 
-// gdb-command:print *unique_dtor
+// gdb-command:print *boxed_with_dtor
 // gdbg-check:$2 = {x = 77, y = 777, z = 7777, w = 77777}
 // gdbr-check:$2 = boxed_struct::StructWithDestructor {x: 77, y: 777, z: 7777, w: 77777}
 
@@ -21,13 +21,13 @@
 
 // lldb-command:run
 
-// lldb-command:print *unique
+// lldb-command:print *boxed_with_padding
 // lldbg-check:[...]$0 = StructWithSomePadding { x: 99, y: 999, z: 9999, w: 99999 }
-// lldbr-check:(boxed_struct::StructWithSomePadding) *unique = StructWithSomePadding { x: 99, y: 999, z: 9999, w: 99999 }
+// lldbr-check:(boxed_struct::StructWithSomePadding) *boxed_with_padding = StructWithSomePadding { x: 99, y: 999, z: 9999, w: 99999 }
 
-// lldb-command:print *unique_dtor
+// lldb-command:print *boxed_with_dtor
 // lldbg-check:[...]$1 = StructWithDestructor { x: 77, y: 777, z: 7777, w: 77777 }
-// lldbr-check:(boxed_struct::StructWithDestructor) *unique_dtor = StructWithDestructor { x: 77, y: 777, z: 7777, w: 77777 }
+// lldbr-check:(boxed_struct::StructWithDestructor) *boxed_with_dtor = StructWithDestructor { x: 77, y: 777, z: 7777, w: 77777 }
 
 #![allow(unused_variables)]
 #![feature(box_syntax)]
@@ -54,9 +54,9 @@ impl Drop for StructWithDestructor {
 
 fn main() {
 
-    let unique: Box<_> = box StructWithSomePadding { x: 99, y: 999, z: 9999, w: 99999 };
+    let boxed_with_padding: Box<_> = box StructWithSomePadding { x: 99, y: 999, z: 9999, w: 99999 };
 
-    let unique_dtor: Box<_> = box StructWithDestructor { x: 77, y: 777, z: 7777, w: 77777 };
+    let boxed_with_dtor: Box<_> = box StructWithDestructor { x: 77, y: 777, z: 7777, w: 77777 };
     zzz(); // #break
 }
 
diff --git a/src/test/rustdoc/auxiliary/through-proc-macro-aux.rs b/src/test/rustdoc/auxiliary/through-proc-macro-aux.rs
new file mode 100644
index 0000000000000..5c4a01ee3a74a
--- /dev/null
+++ b/src/test/rustdoc/auxiliary/through-proc-macro-aux.rs
@@ -0,0 +1,20 @@
+// force-host
+// no-prefer-dynamic
+#![crate_type = "proc-macro"]
+#![crate_name="some_macros"]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn first(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    item // This doesn't erase the spans.
+}
+
+#[proc_macro_attribute]
+pub fn second(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    // Make a new `TokenStream` to erase the spans:
+    let mut out: TokenStream = TokenStream::new();
+    out.extend(item);
+    out
+}
diff --git a/src/test/rustdoc/through-proc-macro.rs b/src/test/rustdoc/through-proc-macro.rs
new file mode 100644
index 0000000000000..348c9eea2dcbf
--- /dev/null
+++ b/src/test/rustdoc/through-proc-macro.rs
@@ -0,0 +1,12 @@
+// aux-build:through-proc-macro-aux.rs
+// build-aux-docs
+#![warn(intra_doc_link_resolution_failure)]
+extern crate some_macros;
+
+#[some_macros::second]
+pub enum Boom {
+    /// [Oooops]
+    Bam,
+}
+
+fn main() {}
diff --git a/src/test/ui-fulldeps/auxiliary/roman-numerals.rs b/src/test/ui-fulldeps/auxiliary/roman-numerals.rs
index 027025b72b31b..2b57e9289b525 100644
--- a/src/test/ui-fulldeps/auxiliary/roman-numerals.rs
+++ b/src/test/ui-fulldeps/auxiliary/roman-numerals.rs
@@ -15,12 +15,12 @@ extern crate rustc;
 extern crate rustc_driver;
 
 use syntax::parse::token::{self, Token};
-use syntax::tokenstream::TokenTree;
+use syntax::tokenstream::{TokenTree, TokenStream};
 use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacEager};
 use syntax_pos::Span;
 use rustc_driver::plugin::Registry;
 
-fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
+fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: TokenStream)
         -> Box<dyn MacResult + 'static> {
 
     static NUMERALS: &'static [(&'static str, usize)] = &[
@@ -36,7 +36,7 @@ fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
         return DummyResult::any(sp);
     }
 
-    let text = match args[0] {
+    let text = match args.into_trees().next().unwrap() {
         TokenTree::Token(Token { kind: token::Ident(s, _), .. }) => s.to_string(),
         _ => {
             cx.span_err(sp, "argument should be a single identifier");
diff --git a/src/test/ui/consts/const-err2.rs b/src/test/ui/consts/const-err2.rs
index a5f685a159b39..ecbcc2a4b496f 100644
--- a/src/test/ui/consts/const-err2.rs
+++ b/src/test/ui/consts/const-err2.rs
@@ -5,6 +5,7 @@
 
 #![feature(rustc_attrs)]
 #![allow(exceeding_bitshifts)]
+
 #![deny(const_err)]
 
 fn black_box<T>(_: T) {
@@ -21,7 +22,7 @@ fn main() {
     let d = 42u8 - (42u8 + 1);
     //~^ ERROR const_err
     let _e = [5u8][1];
-    //~^ ERROR const_err
+    //~^ ERROR index out of bounds
     black_box(a);
     black_box(b);
     black_box(c);
diff --git a/src/test/ui/consts/const-err2.stderr b/src/test/ui/consts/const-err2.stderr
index 659c3afc618a9..1d84d44dc27b3 100644
--- a/src/test/ui/consts/const-err2.stderr
+++ b/src/test/ui/consts/const-err2.stderr
@@ -1,35 +1,35 @@
 error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:15:13
+  --> $DIR/const-err2.rs:16:13
    |
 LL |     let a = -std::i8::MIN;
    |             ^^^^^^^^^^^^^ attempt to negate with overflow
    |
 note: lint level defined here
-  --> $DIR/const-err2.rs:8:9
+  --> $DIR/const-err2.rs:9:9
    |
 LL | #![deny(const_err)]
    |         ^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:17:13
+  --> $DIR/const-err2.rs:18:13
    |
 LL |     let b = 200u8 + 200u8 + 200u8;
    |             ^^^^^^^^^^^^^ attempt to add with overflow
 
 error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:19:13
+  --> $DIR/const-err2.rs:20:13
    |
 LL |     let c = 200u8 * 4;
    |             ^^^^^^^^^ attempt to multiply with overflow
 
 error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:21:13
+  --> $DIR/const-err2.rs:22:13
    |
 LL |     let d = 42u8 - (42u8 + 1);
    |             ^^^^^^^^^^^^^^^^^ attempt to subtract with overflow
 
 error: index out of bounds: the len is 1 but the index is 1
-  --> $DIR/const-err2.rs:23:14
+  --> $DIR/const-err2.rs:24:14
    |
 LL |     let _e = [5u8][1];
    |              ^^^^^^^^
diff --git a/src/test/ui/consts/const-err3.rs b/src/test/ui/consts/const-err3.rs
new file mode 100644
index 0000000000000..a9cf04cda7a5a
--- /dev/null
+++ b/src/test/ui/consts/const-err3.rs
@@ -0,0 +1,30 @@
+// needed because negating int::MIN will behave differently between
+// optimized compilation and unoptimized compilation and thus would
+// lead to different lints being emitted
+// compile-flags: -C overflow-checks=on -O
+
+#![feature(rustc_attrs)]
+#![allow(exceeding_bitshifts)]
+
+#![deny(const_err)]
+
+fn black_box<T>(_: T) {
+    unimplemented!()
+}
+
+fn main() {
+    let a = -std::i8::MIN;
+    //~^ ERROR const_err
+    let b = 200u8 + 200u8 + 200u8;
+    //~^ ERROR const_err
+    let c = 200u8 * 4;
+    //~^ ERROR const_err
+    let d = 42u8 - (42u8 + 1);
+    //~^ ERROR const_err
+    let _e = [5u8][1];
+    //~^ ERROR const_err
+    black_box(a);
+    black_box(b);
+    black_box(c);
+    black_box(d);
+}
diff --git a/src/test/ui/consts/const-err3.stderr b/src/test/ui/consts/const-err3.stderr
new file mode 100644
index 0000000000000..0602707be7040
--- /dev/null
+++ b/src/test/ui/consts/const-err3.stderr
@@ -0,0 +1,38 @@
+error: attempt to negate with overflow
+  --> $DIR/const-err3.rs:16:13
+   |
+LL |     let a = -std::i8::MIN;
+   |             ^^^^^^^^^^^^^
+   |
+note: lint level defined here
+  --> $DIR/const-err3.rs:9:9
+   |
+LL | #![deny(const_err)]
+   |         ^^^^^^^^^
+
+error: attempt to add with overflow
+  --> $DIR/const-err3.rs:18:13
+   |
+LL |     let b = 200u8 + 200u8 + 200u8;
+   |             ^^^^^^^^^^^^^
+
+error: attempt to multiply with overflow
+  --> $DIR/const-err3.rs:20:13
+   |
+LL |     let c = 200u8 * 4;
+   |             ^^^^^^^^^
+
+error: attempt to subtract with overflow
+  --> $DIR/const-err3.rs:22:13
+   |
+LL |     let d = 42u8 - (42u8 + 1);
+   |             ^^^^^^^^^^^^^^^^^
+
+error: index out of bounds: the len is 1 but the index is 1
+  --> $DIR/const-err3.rs:24:14
+   |
+LL |     let _e = [5u8][1];
+   |              ^^^^^^^^
+
+error: aborting due to 5 previous errors
+
diff --git a/src/test/ui/consts/const-eval/promoted_errors.rs b/src/test/ui/consts/const-eval/promoted_errors.rs
index cd989731452b3..45941398f4b66 100644
--- a/src/test/ui/consts/const-eval/promoted_errors.rs
+++ b/src/test/ui/consts/const-eval/promoted_errors.rs
@@ -5,7 +5,7 @@
 fn main() {
     println!("{}", 0u32 - 1);
     let _x = 0u32 - 1;
-    //~^ ERROR this expression will panic at runtime [const_err]
+    //~^ ERROR const_err
     println!("{}", 1/(1-1));
     //~^ ERROR attempt to divide by zero [const_err]
     //~| ERROR reaching this expression at runtime will panic or abort [const_err]
diff --git a/src/test/ui/consts/const-eval/promoted_errors2.rs b/src/test/ui/consts/const-eval/promoted_errors2.rs
new file mode 100644
index 0000000000000..7adb394144bdd
--- /dev/null
+++ b/src/test/ui/consts/const-eval/promoted_errors2.rs
@@ -0,0 +1,22 @@
+// compile-flags: -C overflow-checks=on -O
+
+#![deny(const_err)]
+
+fn main() {
+    println!("{}", 0u32 - 1);
+    //~^ ERROR attempt to subtract with overflow
+    let _x = 0u32 - 1;
+    //~^ ERROR attempt to subtract with overflow
+    println!("{}", 1/(1-1));
+    //~^ ERROR attempt to divide by zero [const_err]
+    //~| ERROR reaching this expression at runtime will panic or abort [const_err]
+    let _x = 1/(1-1);
+    //~^ ERROR const_err
+    //~| ERROR const_err
+    println!("{}", 1/(false as u32));
+    //~^ ERROR attempt to divide by zero [const_err]
+    //~| ERROR reaching this expression at runtime will panic or abort [const_err]
+    let _x = 1/(false as u32);
+    //~^ ERROR const_err
+    //~| ERROR const_err
+}
diff --git a/src/test/ui/consts/const-eval/promoted_errors2.stderr b/src/test/ui/consts/const-eval/promoted_errors2.stderr
new file mode 100644
index 0000000000000..2819e6e8fdbe0
--- /dev/null
+++ b/src/test/ui/consts/const-eval/promoted_errors2.stderr
@@ -0,0 +1,68 @@
+error: attempt to subtract with overflow
+  --> $DIR/promoted_errors2.rs:6:20
+   |
+LL |     println!("{}", 0u32 - 1);
+   |                    ^^^^^^^^
+   |
+note: lint level defined here
+  --> $DIR/promoted_errors2.rs:3:9
+   |
+LL | #![deny(const_err)]
+   |         ^^^^^^^^^
+
+error: attempt to subtract with overflow
+  --> $DIR/promoted_errors2.rs:8:14
+   |
+LL |     let _x = 0u32 - 1;
+   |              ^^^^^^^^
+
+error: attempt to divide by zero
+  --> $DIR/promoted_errors2.rs:10:20
+   |
+LL |     println!("{}", 1/(1-1));
+   |                    ^^^^^^^
+
+error: reaching this expression at runtime will panic or abort
+  --> $DIR/promoted_errors2.rs:10:20
+   |
+LL |     println!("{}", 1/(1-1));
+   |                    ^^^^^^^ attempt to divide by zero
+
+error: attempt to divide by zero
+  --> $DIR/promoted_errors2.rs:13:14
+   |
+LL |     let _x = 1/(1-1);
+   |              ^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/promoted_errors2.rs:13:14
+   |
+LL |     let _x = 1/(1-1);
+   |              ^^^^^^^ attempt to divide by zero
+
+error: attempt to divide by zero
+  --> $DIR/promoted_errors2.rs:16:20
+   |
+LL |     println!("{}", 1/(false as u32));
+   |                    ^^^^^^^^^^^^^^^^
+
+error: reaching this expression at runtime will panic or abort
+  --> $DIR/promoted_errors2.rs:16:20
+   |
+LL |     println!("{}", 1/(false as u32));
+   |                    ^^^^^^^^^^^^^^^^ attempt to divide by zero
+
+error: attempt to divide by zero
+  --> $DIR/promoted_errors2.rs:19:14
+   |
+LL |     let _x = 1/(false as u32);
+   |              ^^^^^^^^^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/promoted_errors2.rs:19:14
+   |
+LL |     let _x = 1/(false as u32);
+   |              ^^^^^^^^^^^^^^^^ attempt to divide by zero
+
+error: aborting due to 10 previous errors
+
diff --git a/src/test/ui/consts/issue-64059-2.rs b/src/test/ui/consts/issue-64059-2.rs
new file mode 100644
index 0000000000000..38911c3dcf692
--- /dev/null
+++ b/src/test/ui/consts/issue-64059-2.rs
@@ -0,0 +1,6 @@
+// compile-flags: -C overflow-checks=on -O
+// run-pass
+
+fn main() {
+    let _ = -(-0.0);
+}
diff --git a/src/test/ui/consts/issue-64059.rs b/src/test/ui/consts/issue-64059.rs
new file mode 100644
index 0000000000000..c4c895fef66cf
--- /dev/null
+++ b/src/test/ui/consts/issue-64059.rs
@@ -0,0 +1,5 @@
+// run-pass
+
+fn main() {
+    let _ = -(-0.0);
+}
diff --git a/src/test/ui/issues/issue-8460-const.rs b/src/test/ui/issues/issue-8460-const.rs
index 611d280f774c0..4637814b277a4 100644
--- a/src/test/ui/issues/issue-8460-const.rs
+++ b/src/test/ui/issues/issue-8460-const.rs
@@ -1,3 +1,5 @@
+// compile-flags: -O
+
 #![deny(const_err)]
 
 use std::{isize, i8, i16, i32, i64};
diff --git a/src/test/ui/issues/issue-8460-const.stderr b/src/test/ui/issues/issue-8460-const.stderr
index 31b1da4f804ab..7e5a22e651ee5 100644
--- a/src/test/ui/issues/issue-8460-const.stderr
+++ b/src/test/ui/issues/issue-8460-const.stderr
@@ -1,245 +1,245 @@
 error: attempt to divide with overflow
-  --> $DIR/issue-8460-const.rs:7:36
+  --> $DIR/issue-8460-const.rs:9:36
    |
 LL |     assert!(thread::spawn(move|| { isize::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^^^
    |
 note: lint level defined here
-  --> $DIR/issue-8460-const.rs:1:9
+  --> $DIR/issue-8460-const.rs:3:9
    |
 LL | #![deny(const_err)]
    |         ^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:7:36
+  --> $DIR/issue-8460-const.rs:9:36
    |
 LL |     assert!(thread::spawn(move|| { isize::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^^^ attempt to divide with overflow
 
 error: attempt to divide with overflow
-  --> $DIR/issue-8460-const.rs:10:36
+  --> $DIR/issue-8460-const.rs:12:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:10:36
+  --> $DIR/issue-8460-const.rs:12:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^ attempt to divide with overflow
 
 error: attempt to divide with overflow
-  --> $DIR/issue-8460-const.rs:13:36
+  --> $DIR/issue-8460-const.rs:15:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:13:36
+  --> $DIR/issue-8460-const.rs:15:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to divide with overflow
 
 error: attempt to divide with overflow
-  --> $DIR/issue-8460-const.rs:16:36
+  --> $DIR/issue-8460-const.rs:18:36
    |
 LL |     assert!(thread::spawn(move|| { i32::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:16:36
+  --> $DIR/issue-8460-const.rs:18:36
    |
 LL |     assert!(thread::spawn(move|| { i32::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to divide with overflow
 
 error: attempt to divide with overflow
-  --> $DIR/issue-8460-const.rs:19:36
+  --> $DIR/issue-8460-const.rs:21:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:19:36
+  --> $DIR/issue-8460-const.rs:21:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to divide with overflow
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:22:36
+  --> $DIR/issue-8460-const.rs:24:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
    |                                    ^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:22:36
+  --> $DIR/issue-8460-const.rs:24:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
    |                                    ^^^^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:25:36
+  --> $DIR/issue-8460-const.rs:27:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
    |                                    ^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:25:36
+  --> $DIR/issue-8460-const.rs:27:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
    |                                    ^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:28:36
+  --> $DIR/issue-8460-const.rs:30:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:28:36
+  --> $DIR/issue-8460-const.rs:30:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:31:36
+  --> $DIR/issue-8460-const.rs:33:36
    |
 LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:31:36
+  --> $DIR/issue-8460-const.rs:33:36
    |
 LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:34:36
+  --> $DIR/issue-8460-const.rs:36:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:34:36
+  --> $DIR/issue-8460-const.rs:36:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to divide by zero
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:37:36
+  --> $DIR/issue-8460-const.rs:39:36
    |
 LL |     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:37:36
+  --> $DIR/issue-8460-const.rs:39:36
    |
 LL |     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:40:36
+  --> $DIR/issue-8460-const.rs:42:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:40:36
+  --> $DIR/issue-8460-const.rs:42:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:43:36
+  --> $DIR/issue-8460-const.rs:45:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:43:36
+  --> $DIR/issue-8460-const.rs:45:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:46:36
+  --> $DIR/issue-8460-const.rs:48:36
    |
 LL |     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:46:36
+  --> $DIR/issue-8460-const.rs:48:36
    |
 LL |     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:49:36
+  --> $DIR/issue-8460-const.rs:51:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:49:36
+  --> $DIR/issue-8460-const.rs:51:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:52:36
+  --> $DIR/issue-8460-const.rs:54:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
    |                                    ^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:52:36
+  --> $DIR/issue-8460-const.rs:54:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
    |                                    ^^^^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:55:36
+  --> $DIR/issue-8460-const.rs:57:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
    |                                    ^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:55:36
+  --> $DIR/issue-8460-const.rs:57:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
    |                                    ^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:58:36
+  --> $DIR/issue-8460-const.rs:60:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:58:36
+  --> $DIR/issue-8460-const.rs:60:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:61:36
+  --> $DIR/issue-8460-const.rs:63:36
    |
 LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:61:36
+  --> $DIR/issue-8460-const.rs:63:36
    |
 LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:64:36
+  --> $DIR/issue-8460-const.rs:66:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:64:36
+  --> $DIR/issue-8460-const.rs:66:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
diff --git a/src/test/ui/issues/issue-8460-const2.rs b/src/test/ui/issues/issue-8460-const2.rs
new file mode 100644
index 0000000000000..c3f53e3298b2b
--- /dev/null
+++ b/src/test/ui/issues/issue-8460-const2.rs
@@ -0,0 +1,59 @@
+// compile-flags: -C overflow-checks=on -O
+
+#![deny(const_err)]
+
+use std::{isize, i8, i16, i32, i64};
+use std::thread;
+
+fn main() {
+    assert!(thread::spawn(move|| { isize::MIN / -1; }).join().is_err());
+    //~^ ERROR attempt to divide with overflow
+    assert!(thread::spawn(move|| { i8::MIN / -1; }).join().is_err());
+    //~^ ERROR attempt to divide with overflow
+    assert!(thread::spawn(move|| { i16::MIN / -1; }).join().is_err());
+    //~^ ERROR attempt to divide with overflow
+    assert!(thread::spawn(move|| { i32::MIN / -1; }).join().is_err());
+    //~^ ERROR attempt to divide with overflow
+    assert!(thread::spawn(move|| { i64::MIN / -1; }).join().is_err());
+    //~^ ERROR attempt to divide with overflow
+    assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
+    //~^ ERROR attempt to divide by zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
+    //~^ ERROR attempt to divide by zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
+    //~^ ERROR attempt to divide by zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
+    //~^ ERROR attempt to divide by zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
+    //~^ ERROR attempt to divide by zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with overflow
+    assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with overflow
+    assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with overflow
+    assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with overflow
+    assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with overflow
+    assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with a divisor of zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with a divisor of zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with a divisor of zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with a divisor of zero
+    //~| ERROR this expression will panic at runtime
+    assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
+    //~^ ERROR attempt to calculate the remainder with a divisor of zero
+    //~| ERROR this expression will panic at runtime
+}
diff --git a/src/test/ui/issues/issue-8460-const2.stderr b/src/test/ui/issues/issue-8460-const2.stderr
new file mode 100644
index 0000000000000..b688ec1367794
--- /dev/null
+++ b/src/test/ui/issues/issue-8460-const2.stderr
@@ -0,0 +1,188 @@
+error: attempt to divide with overflow
+  --> $DIR/issue-8460-const2.rs:9:36
+   |
+LL |     assert!(thread::spawn(move|| { isize::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^^^
+   |
+note: lint level defined here
+  --> $DIR/issue-8460-const2.rs:3:9
+   |
+LL | #![deny(const_err)]
+   |         ^^^^^^^^^
+
+error: attempt to divide with overflow
+  --> $DIR/issue-8460-const2.rs:11:36
+   |
+LL |     assert!(thread::spawn(move|| { i8::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^
+
+error: attempt to divide with overflow
+  --> $DIR/issue-8460-const2.rs:13:36
+   |
+LL |     assert!(thread::spawn(move|| { i16::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^
+
+error: attempt to divide with overflow
+  --> $DIR/issue-8460-const2.rs:15:36
+   |
+LL |     assert!(thread::spawn(move|| { i32::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^
+
+error: attempt to divide with overflow
+  --> $DIR/issue-8460-const2.rs:17:36
+   |
+LL |     assert!(thread::spawn(move|| { i64::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^
+
+error: attempt to divide by zero
+  --> $DIR/issue-8460-const2.rs:19:36
+   |
+LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
+   |                                    ^^^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:19:36
+   |
+LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
+   |                                    ^^^^^^^^^^ attempt to divide by zero
+
+error: attempt to divide by zero
+  --> $DIR/issue-8460-const2.rs:22:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
+   |                                    ^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:22:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
+   |                                    ^^^^^^^ attempt to divide by zero
+
+error: attempt to divide by zero
+  --> $DIR/issue-8460-const2.rs:25:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:25:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
+   |                                    ^^^^^^^^ attempt to divide by zero
+
+error: attempt to divide by zero
+  --> $DIR/issue-8460-const2.rs:28:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:28:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
+   |                                    ^^^^^^^^ attempt to divide by zero
+
+error: attempt to divide by zero
+  --> $DIR/issue-8460-const2.rs:31:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:31:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
+   |                                    ^^^^^^^^ attempt to divide by zero
+
+error: attempt to calculate the remainder with overflow
+  --> $DIR/issue-8460-const2.rs:34:36
+   |
+LL |     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^^^
+
+error: attempt to calculate the remainder with overflow
+  --> $DIR/issue-8460-const2.rs:36:36
+   |
+LL |     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^
+
+error: attempt to calculate the remainder with overflow
+  --> $DIR/issue-8460-const2.rs:38:36
+   |
+LL |     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^
+
+error: attempt to calculate the remainder with overflow
+  --> $DIR/issue-8460-const2.rs:40:36
+   |
+LL |     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^
+
+error: attempt to calculate the remainder with overflow
+  --> $DIR/issue-8460-const2.rs:42:36
+   |
+LL |     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^
+
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const2.rs:44:36
+   |
+LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
+   |                                    ^^^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:44:36
+   |
+LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
+   |                                    ^^^^^^^^^^ attempt to calculate the remainder with a divisor of zero
+
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const2.rs:47:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
+   |                                    ^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:47:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
+   |                                    ^^^^^^^ attempt to calculate the remainder with a divisor of zero
+
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const2.rs:50:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:50:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
+   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
+
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const2.rs:53:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:53:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
+   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
+
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const2.rs:56:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const2.rs:56:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
+   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
+
+error: aborting due to 30 previous errors
+