Auto merge of #61758 - Centril:rollup-ew2uxng, r=Centril

Rollup of 9 pull requests

Successful merges:

 - #60187 (Generator optimization: Overlap locals that never have storage live at the same time)
 - #61348 (Implement Clone::clone_from for Option and Result)
 - #61568 (Use Symbol, Span in libfmt_macros)
 - #61632 (ci: Collect CPU usage statistics on Azure)
 - #61654 (use pattern matching for slices destructuring)
 - #61671 (implement nth_back for Range(Inclusive))
 - #61688 (is_fp and is_floating_point do the same thing, remove the former)
 - #61705 (Pass cflags rather than cxxflags to LLVM as CMAKE_C_FLAGS)
 - #61734 (Migrate rust-by-example to MdBook2)

Failed merges:

r? @ghost

30 files changed, 578 insertions, 233 deletions

diff --git a/.azure-pipelines/steps/run.yml b/.azure-pipelines/steps/run.yml
index 49bac629e72..4875e2c6754 100644
--- a/.azure-pipelines/steps/run.yml
+++ b/.azure-pipelines/steps/run.yml
@@ -11,6 +11,12 @@ steps:
 - checkout: self
   fetchDepth: 2
 
+# Spawn a background process to collect CPU usage statistics which we'll upload
+# at the end of the build. See the comments in the script here for more
+# information.
+- bash: python src/ci/cpu-usage-over-time.py &> cpu-usage.csv &
+  displayName: "Collect CPU-usage statistics in the background"
+
 - bash: printenv | sort
   displayName: Show environment variables
 
@@ -142,3 +148,13 @@ steps:
     AWS_SECRET_ACCESS_KEY: $(AWS_SECRET_ACCESS_KEY)
   condition: and(succeeded(), or(eq(variables.DEPLOY, '1'), eq(variables.DEPLOY_ALT, '1')))
   displayName: Upload artifacts
+
+# Upload CPU usage statistics that we've been gathering this whole time. Always
+# execute this step in case we want to inspect failed builds, but don't let
+# errors here ever fail the build since this is just informational.
+- bash: aws s3 cp --acl public-read cpu-usage.csv s3://$DEPLOY_BUCKET/rustc-builds/$BUILD_SOURCEVERSION/cpu-$SYSTEM_JOBNAME.csv
+  env:
+    AWS_SECRET_ACCESS_KEY: $(AWS_SECRET_ACCESS_KEY)
+  condition: contains(variables, 'AWS_SECRET_ACCESS_KEY')
+  continueOnError: true
+  displayName: Upload CPU usage statistics
diff --git a/Cargo.lock b/Cargo.lock
index 948074ce0fc..10beb3af6ea 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -910,6 +910,9 @@ dependencies = [
 [[package]]
 name = "fmt_macros"
 version = "0.0.0"
+dependencies = [
+ "syntax_pos 0.0.0",
+]
 
 [[package]]
 name = "fnv"
diff --git a/src/bootstrap/doc.rs b/src/bootstrap/doc.rs
index 2a3577a3d20..278ae8a9add 100644
--- a/src/bootstrap/doc.rs
+++ b/src/bootstrap/doc.rs
@@ -64,7 +64,7 @@ book!(
     EmbeddedBook, "src/doc/embedded-book", "embedded-book", RustbookVersion::MdBook2;
     Nomicon, "src/doc/nomicon", "nomicon", RustbookVersion::MdBook2;
     Reference, "src/doc/reference", "reference", RustbookVersion::MdBook1;
-    RustByExample, "src/doc/rust-by-example", "rust-by-example", RustbookVersion::MdBook1;
+    RustByExample, "src/doc/rust-by-example", "rust-by-example", RustbookVersion::MdBook2;
     RustcBook, "src/doc/rustc", "rustc", RustbookVersion::MdBook1;
     RustdocBook, "src/doc/rustdoc", "rustdoc", RustbookVersion::MdBook2;
 );
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index bf3601cb312..8b6e856a8ab 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -416,7 +416,7 @@ fn configure_cmake(builder: &Builder<'_>,
 
     cfg.build_arg("-j").build_arg(builder.jobs().to_string());
     let mut cflags = builder.cflags(target, GitRepo::Llvm).join(" ");
-    if let Some(ref s) = builder.config.llvm_cxxflags {
+    if let Some(ref s) = builder.config.llvm_cflags {
         cflags.push_str(&format!(" {}", s));
     }
     cfg.define("CMAKE_C_FLAGS", cflags);
diff --git a/src/ci/cpu-usage-over-time.py b/src/ci/cpu-usage-over-time.py
new file mode 100644
index 00000000000..78427a6360a
--- /dev/null
+++ b/src/ci/cpu-usage-over-time.py
@@ -0,0 +1,175 @@
+#!/usr/bin/env python
+# ignore-tidy-linelength
+
+# This is a small script that we use on CI to collect CPU usage statistics of
+# our builders. By seeing graphs of CPU usage over time we hope to correlate
+# that with possible improvements to Rust's own build system, ideally diagnosing
+# that either builders are always fully using their CPU resources or they're
+# idle for long stretches of time.
+#
+# This script is relatively simple, but it's platform specific. Each platform
+# (OSX/Windows/Linux) has a different way of calculating the current state of
+# CPU at a point in time. We then compare two captured states to determine the
+# percentage of time spent in one state versus another. The state capturing is
+# all platform-specific but the loop at the bottom is the cross platform part
+# that executes everywhere.
+#
+# # Viewing statistics
+#
+# All builders will upload their CPU statistics as CSV files to our S3 buckets.
+# These URLS look like:
+#
+#   https://$bucket.s3.amazonaws.com/rustc-builds/$commit/cpu-$builder.csv
+#
+# for example
+#
+#   https://rust-lang-ci2.s3.amazonaws.com/rustc-builds/68baada19cd5340f05f0db15a3e16d6671609bcc/cpu-x86_64-apple.csv
+#
+# Each CSV file has two columns. The first is the timestamp of the measurement
+# and the second column is the % of idle cpu time in that time slice. Ideally
+# the second column is always zero.
+#
+# Once you've downloaded a file there's various ways to plot it and visualize
+# it. For command line usage you can use a script like so:
+#
+#      set timefmt '%Y-%m-%dT%H:%M:%S'
+#      set xdata time
+#      set ylabel "Idle CPU %"
+#      set xlabel "Time"
+#      set datafile sep ','
+#      set term png
+#      set output "printme.png"
+#      set grid
+#      builder = "i686-apple"
+#      plot "cpu-".builder.".csv" using 1:2 with lines title builder
+#
+# Executed as `gnuplot < ./foo.plot` it will generate a graph called
+# `printme.png` which you can then open up. If you know how to improve this
+# script or the viewing process that would be much appreciated :) (or even if
+# you know how to automate it!)
+
+import datetime
+import sys
+import time
+
+if sys.platform == 'linux2':
+    class State:
+        def __init__(self):
+            with open('/proc/stat', 'r') as file:
+                data = file.readline().split()
+            if data[0] != 'cpu':
+                raise Exception('did not start with "cpu"')
+            self.user = int(data[1])
+            self.nice = int(data[2])
+            self.system = int(data[3])
+            self.idle = int(data[4])
+            self.iowait = int(data[5])
+            self.irq = int(data[6])
+            self.softirq = int(data[7])
+            self.steal = int(data[8])
+            self.guest = int(data[9])
+            self.guest_nice = int(data[10])
+
+        def idle_since(self, prev):
+            user = self.user - prev.user
+            nice = self.nice - prev.nice
+            system = self.system - prev.system
+            idle = self.idle - prev.idle
+            iowait = self.iowait - prev.iowait
+            irq = self.irq - prev.irq
+            softirq = self.softirq - prev.softirq
+            steal = self.steal - prev.steal
+            guest = self.guest - prev.guest
+            guest_nice = self.guest_nice - prev.guest_nice
+            total = user + nice + system + idle + iowait + irq + softirq + steal + guest + guest_nice
+            return float(idle) / float(total) * 100
+
+elif sys.platform == 'win32':
+    from ctypes.wintypes import DWORD
+    from ctypes import Structure, windll, WinError, GetLastError, byref
+
+    class FILETIME(Structure):
+        _fields_ = [
+            ("dwLowDateTime", DWORD),
+            ("dwHighDateTime", DWORD),
+        ]
+
+    class State:
+        def __init__(self):
+            idle, kernel, user = FILETIME(), FILETIME(), FILETIME()
+
+            success = windll.kernel32.GetSystemTimes(
+                byref(idle),
+                byref(kernel),
+                byref(user),
+            )
+
+            assert success, WinError(GetLastError())[1]
+
+            self.idle = (idle.dwHighDateTime << 32) | idle.dwLowDateTime
+            self.kernel = (kernel.dwHighDateTime << 32) | kernel.dwLowDateTime
+            self.user = (user.dwHighDateTime << 32) | user.dwLowDateTime
+
+        def idle_since(self, prev):
+            idle = self.idle - prev.idle
+            user = self.user - prev.user
+            kernel = self.kernel - prev.kernel
+            return float(idle) / float(user + kernel) * 100
+
+elif sys.platform == 'darwin':
+    from ctypes import *
+    libc = cdll.LoadLibrary('/usr/lib/libc.dylib')
+
+    PROESSOR_CPU_LOAD_INFO = c_int(2)
+    CPU_STATE_USER = 0
+    CPU_STATE_SYSTEM = 1
+    CPU_STATE_IDLE = 2
+    CPU_STATE_NICE = 3
+    c_int_p = POINTER(c_int)
+
+    class State:
+        def __init__(self):
+            num_cpus_u = c_uint(0)
+            cpu_info = c_int_p()
+            cpu_info_cnt = c_int(0)
+            err = libc.host_processor_info(
+                libc.mach_host_self(),
+                PROESSOR_CPU_LOAD_INFO,
+                byref(num_cpus_u),
+                byref(cpu_info),
+                byref(cpu_info_cnt),
+            )
+            assert err == 0
+            self.user = 0
+            self.system = 0
+            self.idle = 0
+            self.nice = 0
+            cur = 0
+            while cur < cpu_info_cnt.value:
+                self.user += cpu_info[cur + CPU_STATE_USER]
+                self.system += cpu_info[cur + CPU_STATE_SYSTEM]
+                self.idle += cpu_info[cur + CPU_STATE_IDLE]
+                self.nice += cpu_info[cur + CPU_STATE_NICE]
+                cur += num_cpus_u.value
+
+        def idle_since(self, prev):
+            user = self.user - prev.user
+            system = self.system - prev.system
+            idle = self.idle - prev.idle
+            nice = self.nice - prev.nice
+            return float(idle) / float(user + system + idle + nice) * 100.0
+
+else:
+    print('unknown platform', sys.platform)
+    sys.exit(1)
+
+cur_state = State();
+print("Time,Idle")
+while True:
+    time.sleep(1);
+    next_state = State();
+    now = datetime.datetime.utcnow().isoformat()
+    idle = next_state.idle_since(cur_state)
+    print("%s,%s" % (now, idle))
+    sys.stdout.flush()
+    cur_state = next_state
diff --git a/src/doc/rust-by-example b/src/doc/rust-by-example
-Subproject 18566f4dedc3ef5bf61f5f85685d5966db99cc1
+Subproject d8eec1dd65470b9a68e80ac1cba8fad0daac491
diff --git a/src/libcore/iter/range.rs b/src/libcore/iter/range.rs
index 6bbf776fb8f..efda3b263cc 100644
--- a/src/libcore/iter/range.rs
+++ b/src/libcore/iter/range.rs
@@ -281,6 +281,19 @@ impl<A: Step> DoubleEndedIterator for ops::Range<A> {
             None
         }
     }
+
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<A> {
+        if let Some(minus_n) = self.end.sub_usize(n) {
+            if minus_n > self.start {
+                self.end = minus_n.sub_one();
+                return Some(self.end.clone())
+            }
+        }
+
+        self.end = self.start.clone();
+        None
+    }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
@@ -439,6 +452,34 @@ impl<A: Step> DoubleEndedIterator for ops::RangeInclusive<A> {
     }
 
     #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<A> {
+        self.compute_is_empty();
+        if self.is_empty.unwrap_or_default() {
+            return None;
+        }
+
+        if let Some(minus_n) = self.end.sub_usize(n) {
+            use crate::cmp::Ordering::*;
+
+            match minus_n.partial_cmp(&self.start) {
+                Some(Greater) => {
+                    self.is_empty = Some(false);
+                    self.end = minus_n.sub_one();
+                    return Some(minus_n);
+                }
+                Some(Equal) => {
+                    self.is_empty = Some(true);
+                    return Some(minus_n);
+                }
+                _ => {}
+            }
+        }
+
+        self.is_empty = Some(true);
+        None
+    }
+
+    #[inline]
     fn try_rfold<B, F, R>(&mut self, init: B, mut f: F) -> R where
         Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
     {
diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index 6b7f491effb..c75ecb059e8 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -145,7 +145,7 @@ use crate::pin::Pin;
 // which basically means it must be `Option`.
 
 /// The `Option` type. See [the module level documentation](index.html) for more.
-#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
+#[derive(Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub enum Option<T> {
     /// No value
@@ -1041,6 +1041,25 @@ fn expect_failed(msg: &str) -> ! {
 /////////////////////////////////////////////////////////////////////////////
 
 #[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Clone> Clone for Option<T> {
+    #[inline]
+    fn clone(&self) -> Self {
+        match self {
+            Some(x) => Some(x.clone()),
+            None => None,
+        }
+    }
+
+    #[inline]
+    fn clone_from(&mut self, source: &Self) {
+        match (self, source) {
+            (Some(to), Some(from)) => to.clone_from(from),
+            (to, from) => *to = from.clone(),
+        }
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<T> Default for Option<T> {
     /// Returns [`None`][Option::None].
     #[inline]
diff --git a/src/libcore/result.rs b/src/libcore/result.rs
index bf8fd63b644..8a09877ce1f 100644
--- a/src/libcore/result.rs
+++ b/src/libcore/result.rs
@@ -240,7 +240,7 @@ use crate::ops::{self, Deref};
 ///
 /// [`Ok`]: enum.Result.html#variant.Ok
 /// [`Err`]: enum.Result.html#variant.Err
-#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
+#[derive(Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
 #[must_use = "this `Result` may be an `Err` variant, which should be handled"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub enum Result<T, E> {
@@ -1004,6 +1004,27 @@ fn unwrap_failed<E: fmt::Debug>(msg: &str, error: E) -> ! {
 /////////////////////////////////////////////////////////////////////////////
 
 #[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Clone, E: Clone> Clone for Result<T, E> {
+    #[inline]
+    fn clone(&self) -> Self {
+        match self {
+            Ok(x) => Ok(x.clone()),
+            Err(x) => Err(x.clone()),
+        }
+    }
+
+    #[inline]
+    fn clone_from(&mut self, source: &Self) {
+        match (self, source) {
+            (Ok(to), Ok(from)) => to.clone_from(from),
+            (Err(to), Err(from)) => to.clone_from(from),
+            (to, from) => *to = from.clone(),
+        }
+    }
+}
+
+
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<T, E> IntoIterator for Result<T, E> {
     type Item = T;
     type IntoIter = IntoIter<T>;
diff --git a/src/libcore/tests/iter.rs b/src/libcore/tests/iter.rs
index bedb9e75612..020618ae7ae 100644
--- a/src/libcore/tests/iter.rs
+++ b/src/libcore/tests/iter.rs
@@ -1658,6 +1658,23 @@ fn test_range_nth() {
 }
 
 #[test]
+fn test_range_nth_back() {
+    assert_eq!((10..15).nth_back(0), Some(14));
+    assert_eq!((10..15).nth_back(1), Some(13));
+    assert_eq!((10..15).nth_back(4), Some(10));
+    assert_eq!((10..15).nth_back(5), None);
+    assert_eq!((-120..80_i8).nth_back(199), Some(-120));
+
+    let mut r = 10..20;
+    assert_eq!(r.nth_back(2), Some(17));
+    assert_eq!(r, 10..17);
+    assert_eq!(r.nth_back(2), Some(14));
+    assert_eq!(r, 10..14);
+    assert_eq!(r.nth_back(10), None);
+    assert_eq!(r, 10..10);
+}
+
+#[test]
 fn test_range_from_nth() {
     assert_eq!((10..).nth(0), Some(10));
     assert_eq!((10..).nth(1), Some(11));
@@ -1715,6 +1732,26 @@ fn test_range_inclusive_nth() {
 }
 
 #[test]
+fn test_range_inclusive_nth_back() {
+    assert_eq!((10..=15).nth_back(0), Some(15));
+    assert_eq!((10..=15).nth_back(1), Some(14));
+    assert_eq!((10..=15).nth_back(5), Some(10));
+    assert_eq!((10..=15).nth_back(6), None);
+    assert_eq!((-120..=80_i8).nth_back(200), Some(-120));
+
+    let mut r = 10_u8..=20;
+    assert_eq!(r.nth_back(2), Some(18));
+    assert_eq!(r, 10..=17);
+    assert_eq!(r.nth_back(2), Some(15));
+    assert_eq!(r, 10..=14);
+    assert_eq!(r.is_empty(), false);
+    assert_eq!(ExactSizeIterator::is_empty(&r), false);
+    assert_eq!(r.nth_back(10), None);
+    assert_eq!(r.is_empty(), true);
+    assert_eq!(ExactSizeIterator::is_empty(&r), true);
+}
+
+#[test]
 fn test_range_step() {
     #![allow(deprecated)]
 
diff --git a/src/libfmt_macros/Cargo.toml b/src/libfmt_macros/Cargo.toml
index 50779a2d9ad..fc32f21ec4e 100644
--- a/src/libfmt_macros/Cargo.toml
+++ b/src/libfmt_macros/Cargo.toml
@@ -8,3 +8,6 @@ edition = "2018"
 name = "fmt_macros"
 path = "lib.rs"
 crate-type = ["dylib"]
+
+[dependencies]
+syntax_pos = { path = "../libsyntax_pos" }
diff --git a/src/libfmt_macros/lib.rs b/src/libfmt_macros/lib.rs
index 1000f237e84..7d0a0035dc8 100644
--- a/src/libfmt_macros/lib.rs
+++ b/src/libfmt_macros/lib.rs
@@ -25,6 +25,17 @@ use std::str;
 use std::string;
 use std::iter;
 
+use syntax_pos::{InnerSpan, Symbol};
+
+#[derive(Copy, Clone)]
+struct InnerOffset(usize);
+
+impl InnerOffset {
+    fn to(self, end: InnerOffset) -> InnerSpan {
+        InnerSpan::new(self.0, end.0)
+    }
+}
+
 /// A piece is a portion of the format string which represents the next part
 /// to emit. These are emitted as a stream by the `Parser` class.
 #[derive(Copy, Clone, PartialEq)]
@@ -40,7 +51,7 @@ pub enum Piece<'a> {
 #[derive(Copy, Clone, PartialEq)]
 pub struct Argument<'a> {
     /// Where to find this argument
-    pub position: Position<'a>,
+    pub position: Position,
     /// How to format the argument
     pub format: FormatSpec<'a>,
 }
@@ -55,9 +66,9 @@ pub struct FormatSpec<'a> {
     /// Packed version of various flags provided
     pub flags: u32,
     /// The integer precision to use
-    pub precision: Count<'a>,
+    pub precision: Count,
     /// The string width requested for the resulting format
-    pub width: Count<'a>,
+    pub width: Count,
     /// The descriptor string representing the name of the format desired for
     /// this argument, this can be empty or any number of characters, although
     /// it is required to be one word.
@@ -66,16 +77,16 @@ pub struct FormatSpec<'a> {
 
 /// Enum describing where an argument for a format can be located.
 #[derive(Copy, Clone, PartialEq)]
-pub enum Position<'a> {
+pub enum Position {
     /// The argument is implied to be located at an index
     ArgumentImplicitlyIs(usize),
     /// The argument is located at a specific index given in the format
     ArgumentIs(usize),
     /// The argument has a name.
-    ArgumentNamed(&'a str),
+    ArgumentNamed(Symbol),
 }
 
-impl Position<'_> {
+impl Position {
     pub fn index(&self) -> Option<usize> {
         match self {
             ArgumentIs(i) | ArgumentImplicitlyIs(i) => Some(*i),
@@ -120,11 +131,11 @@ pub enum Flag {
 /// A count is used for the precision and width parameters of an integer, and
 /// can reference either an argument or a literal integer.
 #[derive(Copy, Clone, PartialEq)]
-pub enum Count<'a> {
+pub enum Count {
     /// The count is specified explicitly.
     CountIs(usize),
     /// The count is specified by the argument with the given name.
-    CountIsName(&'a str),
+    CountIsName(Symbol),
     /// The count is specified by the argument at the given index.
     CountIsParam(usize),
     /// The count is implied and cannot be explicitly specified.
@@ -135,9 +146,8 @@ pub struct ParseError {
     pub description: string::String,
     pub note: Option<string::String>,
     pub label: string::String,
-    pub start: SpanIndex,
-    pub end: SpanIndex,
-    pub secondary_label: Option<(string::String, SpanIndex, SpanIndex)>,
+    pub span: InnerSpan,
+    pub secondary_label: Option<(string::String, InnerSpan)>,
 }
 
 /// The parser structure for interpreting the input format string. This is
@@ -156,24 +166,15 @@ pub struct Parser<'a> {
     /// `Some(raw count)` when the string is "raw", used to position spans correctly
     style: Option<usize>,
     /// Start and end byte offset of every successfully parsed argument
-    pub arg_places: Vec<(SpanIndex, SpanIndex)>,
+    pub arg_places: Vec<InnerSpan>,
     /// Characters that need to be shifted
     skips: Vec<usize>,
-    /// Span offset of the last opening brace seen, used for error reporting
-    last_opening_brace_pos: Option<SpanIndex>,
+    /// Span of the last opening brace seen, used for error reporting
+    last_opening_brace: Option<InnerSpan>,
     /// Wether the source string is comes from `println!` as opposed to `format!` or `print!`
     append_newline: bool,
 }
 
-#[derive(Clone, Copy, Debug)]
-pub struct SpanIndex(pub usize);
-
-impl SpanIndex {
-    pub fn unwrap(self) -> usize {
-        self.0
-    }
-}
-
 impl<'a> Iterator for Parser<'a> {
     type Item = Piece<'a>;
 
@@ -181,19 +182,20 @@ impl<'a> Iterator for Parser<'a> {
         if let Some(&(pos, c)) = self.cur.peek() {
             match c {
                 '{' => {
-                    let curr_last_brace = self.last_opening_brace_pos;
-                    self.last_opening_brace_pos = Some(self.to_span_index(pos));
+                    let curr_last_brace = self.last_opening_brace;
+                    let byte_pos = self.to_span_index(pos);
+                    self.last_opening_brace = Some(byte_pos.to(InnerOffset(byte_pos.0 + 1)));
                     self.cur.next();
                     if self.consume('{') {
-                        self.last_opening_brace_pos = curr_last_brace;
+                        self.last_opening_brace = curr_last_brace;
 
                         Some(String(self.string(pos + 1)))
                     } else {
                         let arg = self.argument();
-                        if let Some(arg_pos) = self.must_consume('}').map(|end| {
-                            (self.to_span_index(pos), self.to_span_index(end + 1))
-                        }) {
-                            self.arg_places.push(arg_pos);
+                        if let Some(end) = self.must_consume('}') {
+                            let start = self.to_span_index(pos);
+                            let end = self.to_span_index(end + 1);
+                            self.arg_places.push(start.to(end));
                         }
                         Some(NextArgument(arg))
                     }
@@ -208,8 +210,7 @@ impl<'a> Iterator for Parser<'a> {
                             "unmatched `}` found",
                             "unmatched `}`",
                             "if you intended to print `}`, you can escape it using `}}`",
-                            err_pos,
-                            err_pos,
+                            err_pos.to(err_pos),
                         );
                         None
                     }
@@ -241,7 +242,7 @@ impl<'a> Parser<'a> {
             style,
             arg_places: vec![],
             skips,
-            last_opening_brace_pos: None,
+            last_opening_brace: None,
             append_newline,
         }
     }
@@ -253,15 +254,13 @@ impl<'a> Parser<'a> {
         &mut self,
         description: S1,
         label: S2,
-        start: SpanIndex,
-        end: SpanIndex,
+        span: InnerSpan,
     ) {
         self.errors.push(ParseError {
             description: description.into(),
             note: None,
             label: label.into(),
-            start,
-            end,
+            span,
             secondary_label: None,
         });
     }
@@ -274,15 +273,13 @@ impl<'a> Parser<'a> {
         description: S1,
         label: S2,
         note: S3,
-        start: SpanIndex,
-        end: SpanIndex,
+        span: InnerSpan,
     ) {
         self.errors.push(ParseError {
             description: description.into(),
             note: Some(note.into()),
             label: label.into(),
-            start,
-            end,
+            span,
             secondary_label: None,
         });
     }
@@ -303,22 +300,21 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn raw(&self) -> usize {
-        self.style.map(|raw| raw + 1).unwrap_or(0)
-    }
-
-    fn to_span_index(&self, pos: usize) -> SpanIndex {
+    fn to_span_index(&self, pos: usize) -> InnerOffset {
         let mut pos = pos;
+        // This handles the raw string case, the raw argument is the number of #
+        // in r###"..."### (we need to add one because of the `r`).
+        let raw = self.style.map(|raw| raw + 1).unwrap_or(0);
         for skip in &self.skips {
             if pos > *skip {
                 pos += 1;
-            } else if pos == *skip && self.raw() == 0 {
+            } else if pos == *skip && raw == 0 {
                 pos += 1;
             } else {
                 break;
             }
         }
-        SpanIndex(self.raw() + pos + 1)
+        InnerOffset(raw + pos + 1)
     }
 
     /// Forces consumption of the specified character. If the character is not
@@ -336,8 +332,8 @@ impl<'a> Parser<'a> {
                 let label = "expected `}`".to_owned();
                 let (note, secondary_label) = if c == '}' {
                     (Some("if you intended to print `{`, you can escape it using `{{`".to_owned()),
-                     self.last_opening_brace_pos.map(|pos| {
-                        ("because of this opening brace".to_owned(), pos, pos)
+                     self.last_opening_brace.map(|sp| {
+                        ("because of this opening brace".to_owned(), sp)
                      }))
                 } else {
                     (None, None)
@@ -346,8 +342,7 @@ impl<'a> Parser<'a> {
                     description,
                     note,
                     label,
-                    start: pos,
-                    end: pos,
+                    span: pos.to(pos),
                     secondary_label,
                 });
                 None
@@ -361,8 +356,8 @@ impl<'a> Parser<'a> {
                 let label = format!("expected `{:?}`", c);
                 let (note, secondary_label) = if c == '}' {
                     (Some("if you intended to print `{`, you can escape it using `{{`".to_owned()),
-                     self.last_opening_brace_pos.map(|pos| {
-                        ("because of this opening brace".to_owned(), pos, pos)
+                     self.last_opening_brace.map(|sp| {
+                        ("because of this opening brace".to_owned(), sp)
                      }))
                 } else {
                     (None, None)
@@ -371,12 +366,11 @@ impl<'a> Parser<'a> {
                     description,
                     note,
                     label,
-                    start: pos,
-                    end: pos,
+                    span: pos.to(pos),
                     secondary_label,
                 });
             } else {
-                self.err(description, format!("expected `{:?}`", c), pos, pos);
+                self.err(description, format!("expected `{:?}`", c), pos.to(pos));
             }
             None
         }
@@ -435,20 +429,24 @@ impl<'a> Parser<'a> {
     /// integer index of an argument, a named argument, or a blank string.
     /// Returns `Some(parsed_position)` if the position is not implicitly
     /// consuming a macro argument, `None` if it's the case.
-    fn position(&mut self) -> Option<Position<'a>> {
+    fn position(&mut self) -> Option<Position> {
         if let Some(i) = self.integer() {
             Some(ArgumentIs(i))
         } else {
             match self.cur.peek() {
-                Some(&(_, c)) if c.is_alphabetic() => Some(ArgumentNamed(self.word())),
+                Some(&(_, c)) if c.is_alphabetic() => {
+                    Some(ArgumentNamed(Symbol::intern(self.word())))
+                }
                 Some(&(pos, c)) if c == '_' => {
                     let invalid_name = self.string(pos);
                     self.err_with_note(format!("invalid argument name `{}`", invalid_name),
                                        "invalid argument name",
                                        "argument names cannot start with an underscore",
-                                       self.to_span_index(pos),
-                                       self.to_span_index(pos + invalid_name.len()));
-                    Some(ArgumentNamed(invalid_name))
+                                        self.to_span_index(pos).to(
+                                            self.to_span_index(pos + invalid_name.len())
+                                        ),
+                                        );
+                    Some(ArgumentNamed(Symbol::intern(invalid_name)))
                 },
 
                 // This is an `ArgumentNext`.
@@ -556,7 +554,7 @@ impl<'a> Parser<'a> {
     /// Parses a Count parameter at the current position. This does not check
     /// for 'CountIsNextParam' because that is only used in precision, not
     /// width.
-    fn count(&mut self) -> Count<'a> {
+    fn count(&mut self) -> Count {
         if let Some(i) = self.integer() {
             if self.consume('$') {
                 CountIsParam(i)
@@ -570,7 +568,7 @@ impl<'a> Parser<'a> {
                 self.cur = tmp;
                 CountImplied
             } else if self.consume('$') {
-                CountIsName(word)
+                CountIsName(Symbol::intern(word))
             } else {
                 self.cur = tmp;
                 CountImplied
@@ -760,6 +758,8 @@ mod tests {
     }
     #[test]
     fn format_counts() {
+        use syntax_pos::{GLOBALS, Globals, edition};
+        GLOBALS.set(&Globals::new(edition::DEFAULT_EDITION), || {
         same("{:10s}",
              &[NextArgument(Argument {
                    position: ArgumentImplicitlyIs(0),
@@ -815,11 +815,12 @@ mod tests {
                        fill: None,
                        align: AlignUnknown,
                        flags: 0,
-                       precision: CountIsName("b"),
-                       width: CountIsName("a"),
+                       precision: CountIsName(Symbol::intern("b")),
+                       width: CountIsName(Symbol::intern("a")),
                        ty: "s",
                    },
                })]);
+        });
     }
     #[test]
     fn format_flags() {
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index 490501bde73..50d2eeef421 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -353,7 +353,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             _ => {
                 // this is a "direct", user-specified, rather than derived,
                 // obligation.
-                flags.push(("direct".to_owned(), None));
+                flags.push((sym::direct, None));
             }
         }
 
@@ -365,27 +365,27 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             // Currently I'm leaving it for what I need for `try`.
             if self.tcx.trait_of_item(item) == Some(trait_ref.def_id) {
                 let method = self.tcx.item_name(item);
-                flags.push(("from_method".to_owned(), None));
-                flags.push(("from_method".to_owned(), Some(method.to_string())));
+                flags.push((sym::from_method, None));
+                flags.push((sym::from_method, Some(method.to_string())));
             }
         }
         if let Some(t) = self.get_parent_trait_ref(&obligation.cause.code) {
-            flags.push(("parent_trait".to_owned(), Some(t)));
+            flags.push((sym::parent_trait, Some(t)));
         }
 
         if let Some(k) = obligation.cause.span.compiler_desugaring_kind() {
-            flags.push(("from_desugaring".to_owned(), None));
-            flags.push(("from_desugaring".to_owned(), Some(k.name().to_string())));
+            flags.push((sym::from_desugaring, None));
+            flags.push((sym::from_desugaring, Some(k.name().to_string())));
         }
         let generics = self.tcx.generics_of(def_id);
         let self_ty = trait_ref.self_ty();
         // This is also included through the generics list as `Self`,
         // but the parser won't allow you to use it
-        flags.push(("_Self".to_owned(), Some(self_ty.to_string())));
+        flags.push((sym::_Self, Some(self_ty.to_string())));
         if let Some(def) = self_ty.ty_adt_def() {
             // We also want to be able to select self's original
             // signature with no type arguments resolved
-            flags.push(("_Self".to_owned(), Some(self.tcx.type_of(def.did).to_string())));
+            flags.push((sym::_Self, Some(self.tcx.type_of(def.did).to_string())));
         }
 
         for param in generics.params.iter() {
@@ -396,38 +396,38 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 },
                 GenericParamDefKind::Lifetime => continue,
             };
-            let name = param.name.to_string();
+            let name = param.name.as_symbol();
             flags.push((name, Some(value)));
         }
 
         if let Some(true) = self_ty.ty_adt_def().map(|def| def.did.is_local()) {
-            flags.push(("crate_local".to_owned(), None));
+            flags.push((sym::crate_local, None));
         }
 
         // Allow targeting all integers using `{integral}`, even if the exact type was resolved
         if self_ty.is_integral() {
-            flags.push(("_Self".to_owned(), Some("{integral}".to_owned())));
+            flags.push((sym::_Self, Some("{integral}".to_owned())));
         }
 
         if let ty::Array(aty, len) = self_ty.sty {
-            flags.push(("_Self".to_owned(), Some("[]".to_owned())));
-            flags.push(("_Self".to_owned(), Some(format!("[{}]", aty))));
+            flags.push((sym::_Self, Some("[]".to_owned())));
+            flags.push((sym::_Self, Some(format!("[{}]", aty))));
             if let Some(def) = aty.ty_adt_def() {
                 // We also want to be able to select the array's type's original
                 // signature with no type arguments resolved
                 flags.push((
-                    "_Self".to_owned(),
+                    sym::_Self,
                     Some(format!("[{}]", self.tcx.type_of(def.did).to_string())),
                 ));
                 let tcx = self.tcx;
                 if let Some(len) = len.assert_usize(tcx) {
                     flags.push((
-                        "_Self".to_owned(),
+                        sym::_Self,
                         Some(format!("[{}; {}]", self.tcx.type_of(def.did).to_string(), len)),
                     ));
                 } else {
                     flags.push((
-                        "_Self".to_owned(),
+                        sym::_Self,
                         Some(format!("[{}; _]", self.tcx.type_of(def.did).to_string())),
                     ));
                 }
diff --git a/src/librustc/traits/on_unimplemented.rs b/src/librustc/traits/on_unimplemented.rs
index 1c17ace90c2..b78396c90dc 100644
--- a/src/librustc/traits/on_unimplemented.rs
+++ b/src/librustc/traits/on_unimplemented.rs
@@ -7,7 +7,7 @@ use crate::util::nodemap::FxHashMap;
 
 use syntax::ast::{MetaItem, NestedMetaItem};
 use syntax::attr;
-use syntax::symbol::sym;
+use syntax::symbol::{Symbol, kw, sym};
 use syntax_pos::Span;
 use syntax_pos::symbol::LocalInternedString;
 
@@ -52,7 +52,7 @@ fn parse_error(tcx: TyCtxt<'_, '_, '_>, span: Span,
 }
 
 impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
-    pub fn parse(tcx: TyCtxt<'a, 'gcx, 'tcx>,
+    fn parse(tcx: TyCtxt<'a, 'gcx, 'tcx>,
                  trait_def_id: DefId,
                  items: &[NestedMetaItem],
                  span: Span,
@@ -167,7 +167,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
     pub fn evaluate(&self,
                     tcx: TyCtxt<'a, 'gcx, 'tcx>,
                     trait_ref: ty::TraitRef<'tcx>,
-                    options: &[(String, Option<String>)])
+                    options: &[(Symbol, Option<String>)])
                     -> OnUnimplementedNote
     {
         let mut message = None;
@@ -180,7 +180,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
                 if !attr::eval_condition(condition, &tcx.sess.parse_sess, &mut |c| {
                     c.ident().map_or(false, |ident| {
                         options.contains(&(
-                            ident.to_string(),
+                            ident.name,
                             c.value_str().map(|s| s.as_str().to_string())
                         ))
                     })
@@ -203,8 +203,8 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
             }
         }
 
-        let options: FxHashMap<String, String> = options.into_iter()
-            .filter_map(|(k, v)| v.as_ref().map(|v| (k.to_owned(), v.to_owned())))
+        let options: FxHashMap<Symbol, String> = options.into_iter()
+            .filter_map(|(k, v)| v.as_ref().map(|v| (*k, v.to_owned())))
             .collect();
         OnUnimplementedNote {
             label: label.map(|l| l.format(tcx, trait_ref, &options)),
@@ -215,7 +215,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
 }
 
 impl<'a, 'gcx, 'tcx> OnUnimplementedFormatString {
-    pub fn try_parse(tcx: TyCtxt<'a, 'gcx, 'tcx>,
+    fn try_parse(tcx: TyCtxt<'a, 'gcx, 'tcx>,
                      trait_def_id: DefId,
                      from: LocalInternedString,
                      err_sp: Span)
@@ -241,16 +241,16 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedFormatString {
                 Piece::String(_) => (), // Normal string, no need to check it
                 Piece::NextArgument(a) => match a.position {
                     // `{Self}` is allowed
-                    Position::ArgumentNamed(s) if s == "Self" => (),
+                    Position::ArgumentNamed(s) if s == kw::SelfUpper => (),
                     // `{ThisTraitsName}` is allowed
-                    Position::ArgumentNamed(s) if s == name.as_str() => (),
+                    Position::ArgumentNamed(s) if s == name => (),
                     // `{from_method}` is allowed
-                    Position::ArgumentNamed(s) if s == "from_method" => (),
+                    Position::ArgumentNamed(s) if s == sym::from_method => (),
                     // `{from_desugaring}` is allowed
-                    Position::ArgumentNamed(s) if s == "from_desugaring" => (),
+                    Position::ArgumentNamed(s) if s == sym::from_desugaring => (),
                     // So is `{A}` if A is a type parameter
                     Position::ArgumentNamed(s) => match generics.params.iter().find(|param| {
-                        param.name.as_str() == s
+                        param.name.as_symbol() == s
                     }) {
                         Some(_) => (),
                         None => {
@@ -276,7 +276,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedFormatString {
         &self,
         tcx: TyCtxt<'a, 'gcx, 'tcx>,
         trait_ref: ty::TraitRef<'tcx>,
-        options: &FxHashMap<String, String>,
+        options: &FxHashMap<Symbol, String>,
     ) -> String {
         let name = tcx.item_name(trait_ref.def_id);
         let trait_str = tcx.def_path_str(trait_ref.def_id);
@@ -289,9 +289,9 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedFormatString {
                 },
                 GenericParamDefKind::Lifetime => return None
             };
-            let name = param.name.to_string();
+            let name = param.name.as_symbol();
             Some((name, value))
-        }).collect::<FxHashMap<String, String>>();
+        }).collect::<FxHashMap<Symbol, String>>();
         let empty_string = String::new();
 
         let parser = Parser::new(&self.0, None, vec![], false);
@@ -299,15 +299,15 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedFormatString {
             match p {
                 Piece::String(s) => s,
                 Piece::NextArgument(a) => match a.position {
-                    Position::ArgumentNamed(s) => match generic_map.get(s) {
+                    Position::ArgumentNamed(s) => match generic_map.get(&s) {
                         Some(val) => val,
-                        None if s == name.as_str() => {
+                        None if s == name => {
                             &trait_str
                         }
                         None => {
-                            if let Some(val) = options.get(s) {
+                            if let Some(val) = options.get(&s) {
                                 val
-                            } else if s == "from_desugaring" || s == "from_method" {
+                            } else if s == sym::from_desugaring || s == sym::from_method {
                                 // don't break messages using these two arguments incorrectly
                                 &empty_string
                             } else {
diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index abde4d6de2a..0e5c906024c 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -1665,6 +1665,7 @@ impl RegionKind {
 
 /// Type utilities
 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
+    #[inline]
     pub fn is_unit(&self) -> bool {
         match self.sty {
             Tuple(ref tys) => tys.is_empty(),
@@ -1672,6 +1673,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_never(&self) -> bool {
         match self.sty {
             Never => true,
@@ -1726,6 +1728,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_primitive(&self) -> bool {
         match self.sty {
             Bool | Char | Int(_) | Uint(_) | Float(_) => true,
@@ -1741,6 +1744,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_ty_infer(&self) -> bool {
         match self.sty {
             Infer(_) => true,
@@ -1748,6 +1752,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_phantom_data(&self) -> bool {
         if let Adt(def, _) = self.sty {
             def.is_phantom_data()
@@ -1756,8 +1761,10 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_bool(&self) -> bool { self.sty == Bool }
 
+    #[inline]
     pub fn is_param(&self, index: u32) -> bool {
         match self.sty {
             ty::Param(ref data) => data.index == index,
@@ -1765,6 +1772,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_self(&self) -> bool {
         match self.sty {
             Param(ref p) => p.is_self(),
@@ -1772,6 +1780,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_slice(&self) -> bool {
         match self.sty {
             RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
@@ -1814,6 +1823,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_region_ptr(&self) -> bool {
         match self.sty {
             Ref(..) => true,
@@ -1821,6 +1831,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_mutable_pointer(&self) -> bool {
         match self.sty {
             RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
@@ -1829,6 +1840,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_unsafe_ptr(&self) -> bool {
         match self.sty {
             RawPtr(_) => return true,
@@ -1837,6 +1849,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
     }
 
     /// Returns `true` if this type is an `Arc<T>`.
+    #[inline]
     pub fn is_arc(&self) -> bool {
         match self.sty {
             Adt(def, _) => def.is_arc(),
@@ -1845,6 +1858,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
     }
 
     /// Returns `true` if this type is an `Rc<T>`.
+    #[inline]
     pub fn is_rc(&self) -> bool {
         match self.sty {
             Adt(def, _) => def.is_rc(),
@@ -1852,6 +1866,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_box(&self) -> bool {
         match self.sty {
             Adt(def, _) => def.is_box(),
@@ -1870,6 +1885,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
     /// A scalar type is one that denotes an atomic datum, with no sub-components.
     /// (A RawPtr is scalar because it represents a non-managed pointer, so its
     /// contents are abstract to rustc.)
+    #[inline]
     pub fn is_scalar(&self) -> bool {
         match self.sty {
             Bool | Char | Int(_) | Float(_) | Uint(_) |
@@ -1880,6 +1896,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
     }
 
     /// Returns `true` if this type is a floating point type.
+    #[inline]
     pub fn is_floating_point(&self) -> bool {
         match self.sty {
             Float(_) |
@@ -1888,6 +1905,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_trait(&self) -> bool {
         match self.sty {
             Dynamic(..) => true,
@@ -1895,6 +1913,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_enum(&self) -> bool {
         match self.sty {
             Adt(adt_def, _) => {
@@ -1904,6 +1923,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_closure(&self) -> bool {
         match self.sty {
             Closure(..) => true,
@@ -1911,6 +1931,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_generator(&self) -> bool {
         match self.sty {
             Generator(..) => true,
@@ -1926,6 +1947,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_fresh_ty(&self) -> bool {
         match self.sty {
             Infer(FreshTy(_)) => true,
@@ -1933,6 +1955,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_fresh(&self) -> bool {
         match self.sty {
             Infer(FreshTy(_)) => true,
@@ -1942,6 +1965,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_char(&self) -> bool {
         match self.sty {
             Char => true,
@@ -1950,17 +1974,11 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
     }
 
     #[inline]
-    pub fn is_fp(&self) -> bool {
-        match self.sty {
-            Infer(FloatVar(_)) | Float(_) => true,
-            _ => false
-        }
-    }
-
     pub fn is_numeric(&self) -> bool {
-        self.is_integral() || self.is_fp()
+        self.is_integral() || self.is_floating_point()
     }
 
+    #[inline]
     pub fn is_signed(&self) -> bool {
         match self.sty {
             Int(_) => true,
@@ -1968,6 +1986,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_pointer_sized(&self) -> bool {
         match self.sty {
             Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true,
@@ -1975,6 +1994,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_machine(&self) -> bool {
         match self.sty {
             Int(..) | Uint(..) | Float(..) => true,
@@ -1982,6 +2002,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn has_concrete_skeleton(&self) -> bool {
         match self.sty {
             Param(_) | Infer(_) | Error => false,
@@ -2028,6 +2049,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_fn(&self) -> bool {
         match self.sty {
             FnDef(..) | FnPtr(_) => true,
@@ -2043,6 +2065,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
         }
     }
 
+    #[inline]
     pub fn is_impl_trait(&self) -> bool {
         match self.sty {
             Opaque(..) => true,
diff --git a/src/librustc_codegen_ssa/mir/rvalue.rs b/src/librustc_codegen_ssa/mir/rvalue.rs
index 7a2bd18df4e..87e15ba6aac 100644
--- a/src/librustc_codegen_ssa/mir/rvalue.rs
+++ b/src/librustc_codegen_ssa/mir/rvalue.rs
@@ -429,7 +429,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             mir::Rvalue::UnaryOp(op, ref operand) => {
                 let operand = self.codegen_operand(&mut bx, operand);
                 let lloperand = operand.immediate();
-                let is_float = operand.layout.ty.is_fp();
+                let is_float = operand.layout.ty.is_floating_point();
                 let llval = match op {
                     mir::UnOp::Not => bx.not(lloperand),
                     mir::UnOp::Neg => if is_float {
@@ -536,7 +536,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         rhs: Bx::Value,
         input_ty: Ty<'tcx>,
     ) -> Bx::Value {
-        let is_float = input_ty.is_fp();
+        let is_float = input_ty.is_floating_point();
         let is_signed = input_ty.is_signed();
         let is_unit = input_ty.is_unit();
         match op {
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index e35df6cd494..2ab8d14ed32 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4094,7 +4094,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                         hir::UnNeg => {
                             let result = self.check_user_unop(expr, oprnd_t, unop);
                             // If it's builtin, we can reuse the type, this helps inference.
-                            if !(oprnd_t.is_integral() || oprnd_t.is_fp()) {
+                            if !oprnd_t.is_numeric() {
                                 oprnd_t = result;
                             }
                         }
diff --git a/src/librustdoc/passes/check_code_block_syntax.rs b/src/librustdoc/passes/check_code_block_syntax.rs
index 694843ad7f7..6d51278b4e5 100644
--- a/src/librustdoc/passes/check_code_block_syntax.rs
+++ b/src/librustdoc/passes/check_code_block_syntax.rs
@@ -2,7 +2,7 @@ use errors::Applicability;
 use syntax::parse::lexer::{StringReader as Lexer};
 use syntax::parse::{ParseSess, token};
 use syntax::source_map::FilePathMapping;
-use syntax_pos::FileName;
+use syntax_pos::{InnerSpan, FileName};
 
 use crate::clean;
 use crate::core::DocContext;
@@ -63,7 +63,7 @@ impl<'a, 'tcx> SyntaxChecker<'a, 'tcx> {
                 }
 
                 if code_block.syntax.is_none() && code_block.is_fenced {
-                    let sp = sp.from_inner_byte_pos(0, 3);
+                    let sp = sp.from_inner(InnerSpan::new(0, 3));
                     diag.span_suggestion(
                         sp,
                         "mark blocks that do not contain Rust code as text",
diff --git a/src/librustdoc/passes/mod.rs b/src/librustdoc/passes/mod.rs
index 018ab5dea60..8fc6b9fdbe6 100644
--- a/src/librustdoc/passes/mod.rs
+++ b/src/librustdoc/passes/mod.rs
@@ -6,7 +6,7 @@ use rustc::lint as lint;
 use rustc::middle::privacy::AccessLevels;
 use rustc::util::nodemap::DefIdSet;
 use std::mem;
-use syntax_pos::{DUMMY_SP, Span};
+use syntax_pos::{DUMMY_SP, InnerSpan, Span};
 use std::ops::Range;
 
 use crate::clean::{self, GetDefId, Item};
@@ -440,10 +440,10 @@ crate fn source_span_for_markdown_range(
         }
     }
 
-    let sp = span_of_attrs(attrs).from_inner_byte_pos(
+    let sp = 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/libsyntax/diagnostics/plugin.rs b/src/libsyntax/diagnostics/plugin.rs
index 9f01b9b9f9b..98351048c35 100644
--- a/src/libsyntax/diagnostics/plugin.rs
+++ b/src/libsyntax/diagnostics/plugin.rs
@@ -33,8 +33,10 @@ pub fn expand_diagnostic_used<'cx>(ecx: &'cx mut ExtCtxt<'_>,
                                    span: Span,
                                    token_tree: &[TokenTree])
                                    -> Box<dyn MacResult+'cx> {
-    let code = match (token_tree.len(), token_tree.get(0)) {
-        (1, Some(&TokenTree::Token(Token { kind: token::Ident(code, _), .. }))) => code,
+    let code = match token_tree {
+        [
+            TokenTree::Token(Token { kind: token::Ident(code, _), .. })
+        ] => code,
         _ => unreachable!()
     };
 
@@ -66,22 +68,19 @@ pub fn expand_register_diagnostic<'cx>(ecx: &'cx mut ExtCtxt<'_>,
                                        span: Span,
                                        token_tree: &[TokenTree])
                                        -> Box<dyn MacResult+'cx> {
-    let (code, description) = match (
-        token_tree.len(),
-        token_tree.get(0),
-        token_tree.get(1),
-        token_tree.get(2)
-    ) {
-        (1, Some(&TokenTree::Token(Token { kind: token::Ident(code, _), .. })), None, None) => {
-            (code, None)
+    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))
         },
-        (3, Some(&TokenTree::Token(Token { kind: token::Ident(code, _), .. })),
-            Some(&TokenTree::Token(Token { kind: token::Comma, .. })),
-            Some(&TokenTree::Token(Token {
-                kind: token::Literal(token::Lit { symbol, .. }), ..
-            }))) => {
-            (code, Some(symbol))
-        }
         _ => unreachable!()
     };
 
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index cde35681988..dd96c63ab0e 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -424,48 +424,38 @@ mod tests {
                 string_to_stream("macro_rules! zip (($a)=>($a))".to_string()).trees().collect();
             let tts: &[TokenTree] = &tts[..];
 
-            match (tts.len(), tts.get(0), tts.get(1), tts.get(2), tts.get(3)) {
-                (
-                    4,
-                    Some(&TokenTree::Token(Token {
-                        kind: token::Ident(name_macro_rules, false), ..
-                    })),
-                    Some(&TokenTree::Token(Token { kind: token::Not, .. })),
-                    Some(&TokenTree::Token(Token { kind: token::Ident(name_zip, false), .. })),
-                    Some(&TokenTree::Delimited(_, macro_delim, ref macro_tts)),
-                )
-                if name_macro_rules == sym::macro_rules && name_zip.as_str() == "zip" => {
+            match tts {
+                [
+                    TokenTree::Token(Token { kind: token::Ident(name_macro_rules, false), .. }),
+                    TokenTree::Token(Token { kind: token::Not, .. }),
+                    TokenTree::Token(Token { kind: token::Ident(name_zip, false), .. }),
+                    TokenTree::Delimited(_, macro_delim,  macro_tts)
+                ]
+                if name_macro_rules == &sym::macro_rules && name_zip.as_str() == "zip" => {
                     let tts = &macro_tts.trees().collect::<Vec<_>>();
-                    match (tts.len(), tts.get(0), tts.get(1), tts.get(2)) {
-                        (
-                            3,
-                            Some(&TokenTree::Delimited(_, first_delim, ref first_tts)),
-                            Some(&TokenTree::Token(Token { kind: token::FatArrow, .. })),
-                            Some(&TokenTree::Delimited(_, second_delim, ref second_tts)),
-                        )
-                        if macro_delim == token::Paren => {
+                    match &tts[..] {
+                        [
+                            TokenTree::Delimited(_, first_delim, first_tts),
+                            TokenTree::Token(Token { kind: token::FatArrow, .. }),
+                            TokenTree::Delimited(_, second_delim, second_tts),
+                        ]
+                        if macro_delim == &token::Paren => {
                             let tts = &first_tts.trees().collect::<Vec<_>>();
-                            match (tts.len(), tts.get(0), tts.get(1)) {
-                                (
-                                    2,
-                                    Some(&TokenTree::Token(Token { kind: token::Dollar, .. })),
-                                    Some(&TokenTree::Token(Token {
-                                        kind: token::Ident(name, false), ..
-                                    })),
-                                )
-                                if first_delim == token::Paren && name.as_str() == "a" => {},
+                            match &tts[..] {
+                                [
+                                    TokenTree::Token(Token { kind: token::Dollar, .. }),
+                                    TokenTree::Token(Token { kind: token::Ident(name, false), .. }),
+                                ]
+                                if first_delim == &token::Paren && name.as_str() == "a" => {},
                                 _ => panic!("value 3: {:?} {:?}", first_delim, first_tts),
                             }
                             let tts = &second_tts.trees().collect::<Vec<_>>();
-                            match (tts.len(), tts.get(0), tts.get(1)) {
-                                (
-                                    2,
-                                    Some(&TokenTree::Token(Token { kind: token::Dollar, .. })),
-                                    Some(&TokenTree::Token(Token {
-                                        kind: token::Ident(name, false), ..
-                                    })),
-                                )
-                                if second_delim == token::Paren && name.as_str() == "a" => {},
+                            match &tts[..] {
+                                [
+                                    TokenTree::Token(Token { kind: token::Dollar, .. }),
+                                    TokenTree::Token(Token { kind: token::Ident(name, false), .. }),
+                                ]
+                                if second_delim == &token::Paren && name.as_str() == "a" => {},
                                 _ => panic!("value 4: {:?} {:?}", second_delim, second_tts),
                             }
                         },
diff --git a/src/libsyntax_ext/deriving/cmp/ord.rs b/src/libsyntax_ext/deriving/cmp/ord.rs
index b25a9e4c50f..844865d57c7 100644
--- a/src/libsyntax_ext/deriving/cmp/ord.rs
+++ b/src/libsyntax_ext/deriving/cmp/ord.rs
@@ -82,8 +82,8 @@ pub fn cs_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> P<
         // }
 
         let new = {
-            let other_f = match (other_fs.len(), other_fs.get(0)) {
-                (1, Some(o_f)) => o_f,
+            let other_f = match other_fs {
+                [o_f] => o_f,
                 _ => cx.span_bug(span, "not exactly 2 arguments in `derive(Ord)`"),
             };
 
diff --git a/src/libsyntax_ext/deriving/cmp/partial_eq.rs b/src/libsyntax_ext/deriving/cmp/partial_eq.rs
index 6172f27261e..732bb234389 100644
--- a/src/libsyntax_ext/deriving/cmp/partial_eq.rs
+++ b/src/libsyntax_ext/deriving/cmp/partial_eq.rs
@@ -25,8 +25,8 @@ pub fn expand_deriving_partial_eq(cx: &mut ExtCtxt<'_>,
              -> P<Expr>
     {
         let op = |cx: &mut ExtCtxt<'_>, span: Span, self_f: P<Expr>, other_fs: &[P<Expr>]| {
-            let other_f = match (other_fs.len(), other_fs.get(0)) {
-                (1, Some(o_f)) => o_f,
+            let other_f = match other_fs {
+                [o_f] => o_f,
                 _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`"),
             };
 
diff --git a/src/libsyntax_ext/deriving/cmp/partial_ord.rs b/src/libsyntax_ext/deriving/cmp/partial_ord.rs
index 3980741f252..a30a7d78222 100644
--- a/src/libsyntax_ext/deriving/cmp/partial_ord.rs
+++ b/src/libsyntax_ext/deriving/cmp/partial_ord.rs
@@ -143,8 +143,8 @@ pub fn cs_partial_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_
                 // }
 
                 let new = {
-                    let other_f = match (other_fs.len(), other_fs.get(0)) {
-                        (1, Some(o_f)) => o_f,
+                    let other_f = match other_fs {
+                        [o_f] => o_f,
                                 _ => {
                                     cx.span_bug(span,
                                         "not exactly 2 arguments in `derive(PartialOrd)`")
@@ -193,8 +193,8 @@ fn cs_op(less: bool,
     };
 
     let par_cmp = |cx: &mut ExtCtxt<'_>, span, self_f: P<Expr>, other_fs: &[P<Expr>], default| {
-        let other_f = match (other_fs.len(), other_fs.get(0)) {
-            (1, Some(o_f)) => o_f,
+        let other_f = match other_fs {
+            [o_f] => o_f,
             _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialOrd)`"),
         };
 
diff --git a/src/libsyntax_ext/deriving/hash.rs b/src/libsyntax_ext/deriving/hash.rs
index e7f99d45782..7ad04aebf6e 100644
--- a/src/libsyntax_ext/deriving/hash.rs
+++ b/src/libsyntax_ext/deriving/hash.rs
@@ -52,8 +52,8 @@ pub fn expand_deriving_hash(cx: &mut ExtCtxt<'_>,
 }
 
 fn hash_substructure(cx: &mut ExtCtxt<'_>, trait_span: Span, substr: &Substructure<'_>) -> P<Expr> {
-    let state_expr = match (substr.nonself_args.len(), substr.nonself_args.get(0)) {
-        (1, Some(o_f)) => o_f,
+    let state_expr = match &substr.nonself_args {
+        &[o_f] => o_f,
         _ => {
             cx.span_bug(trait_span,
                         "incorrect number of arguments in `derive(Hash)`")
diff --git a/src/libsyntax_ext/format.rs b/src/libsyntax_ext/format.rs
index 377164728f4..85b524786b2 100644
--- a/src/libsyntax_ext/format.rs
+++ b/src/libsyntax_ext/format.rs
@@ -28,7 +28,7 @@ enum ArgumentType {
 
 enum Position {
     Exact(usize),
-    Named(String),
+    Named(Symbol),
 }
 
 struct Context<'a, 'b: 'a> {
@@ -57,7 +57,7 @@ struct Context<'a, 'b: 'a> {
     /// Unique format specs seen for each argument.
     arg_unique_types: Vec<Vec<ArgumentType>>,
     /// Map from named arguments to their resolved indices.
-    names: FxHashMap<String, usize>,
+    names: FxHashMap<Symbol, usize>,
 
     /// The latest consecutive literal strings, or empty if there weren't any.
     literal: String,
@@ -127,9 +127,9 @@ fn parse_args<'a>(
     ecx: &mut ExtCtxt<'a>,
     sp: Span,
     tts: &[tokenstream::TokenTree]
-) -> Result<(P<ast::Expr>, Vec<P<ast::Expr>>, FxHashMap<String, usize>), DiagnosticBuilder<'a>> {
+) -> 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::<String, usize>::default();
+    let mut names = FxHashMap::<Symbol, usize>::default();
 
     let mut p = ecx.new_parser_from_tts(tts);
 
@@ -158,11 +158,10 @@ fn parse_args<'a>(
                     "expected ident, positional arguments cannot follow named arguments",
                 ));
             };
-            let name: &str = &name.as_str();
 
             p.expect(&token::Eq)?;
             let e = p.parse_expr()?;
-            if let Some(prev) = names.get(name) {
+            if let Some(prev) = names.get(&name) {
                 ecx.struct_span_err(e.span, &format!("duplicate argument named `{}`", name))
                     .span_note(args[*prev].span, "previously here")
                     .emit();
@@ -174,7 +173,7 @@ fn parse_args<'a>(
             // if the input is valid, we can simply append to the positional
             // args. And remember the names.
             let slot = args.len();
-            names.insert(name.to_string(), slot);
+            names.insert(name, slot);
             args.push(e);
         } else {
             let e = p.parse_expr()?;
@@ -188,7 +187,7 @@ impl<'a, 'b> Context<'a, 'b> {
     fn resolve_name_inplace(&self, p: &mut parse::Piece<'_>) {
         // NOTE: the `unwrap_or` branch is needed in case of invalid format
         // arguments, e.g., `format_args!("{foo}")`.
-        let lookup = |s| *self.names.get(s).unwrap_or(&0);
+        let lookup = |s: Symbol| *self.names.get(&s).unwrap_or(&0);
 
         match *p {
             parse::String(_) => {}
@@ -222,7 +221,7 @@ impl<'a, 'b> Context<'a, 'b> {
                 // it's written second, so it should come after width/precision.
                 let pos = match arg.position {
                     parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => Exact(i),
-                    parse::ArgumentNamed(s) => Named(s.to_string()),
+                    parse::ArgumentNamed(s) => Named(s),
                 };
 
                 let ty = Placeholder(arg.format.ty.to_string());
@@ -232,7 +231,7 @@ impl<'a, 'b> Context<'a, 'b> {
         }
     }
 
-    fn verify_count(&mut self, c: parse::Count<'_>) {
+    fn verify_count(&mut self, c: parse::Count) {
         match c {
             parse::CountImplied |
             parse::CountIs(..) => {}
@@ -240,7 +239,7 @@ impl<'a, 'b> Context<'a, 'b> {
                 self.verify_arg_type(Exact(i), Count);
             }
             parse::CountIsName(s) => {
-                self.verify_arg_type(Named(s.to_string()), Count);
+                self.verify_arg_type(Named(s), Count);
             }
         }
     }
@@ -390,7 +389,7 @@ impl<'a, 'b> Context<'a, 'b> {
         ecx.std_path(&[sym::fmt, sym::rt, sym::v1, Symbol::intern(s)])
     }
 
-    fn build_count(&self, c: parse::Count<'_>) -> P<ast::Expr> {
+    fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
         let sp = self.macsp;
         let count = |c, arg| {
             let mut path = Context::rtpath(self.ecx, "Count");
@@ -739,7 +738,7 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt<'_>,
                                     sp: Span,
                                     efmt: P<ast::Expr>,
                                     args: Vec<P<ast::Expr>>,
-                                    names: FxHashMap<String, usize>,
+                                    names: FxHashMap<Symbol, usize>,
                                     append_newline: bool)
                                     -> P<ast::Expr> {
     // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
@@ -901,15 +900,15 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt<'_>,
 
     if !parser.errors.is_empty() {
         let err = parser.errors.remove(0);
-        let sp = fmt.span.from_inner_byte_pos(err.start.unwrap(), err.end.unwrap());
+        let sp = fmt.span.from_inner(err.span);
         let mut e = ecx.struct_span_err(sp, &format!("invalid format string: {}",
                                                      err.description));
         e.span_label(sp, err.label + " in format string");
         if let Some(note) = err.note {
             e.note(&note);
         }
-        if let Some((label, start, end)) = err.secondary_label {
-            let sp = fmt.span.from_inner_byte_pos(start.unwrap(), end.unwrap());
+        if let Some((label, span)) = err.secondary_label {
+            let sp = fmt.span.from_inner(span);
             e.span_label(sp, label);
         }
         e.emit();
@@ -917,9 +916,7 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt<'_>,
     }
 
     let arg_spans = parser.arg_places.iter()
-        .map(|&(parse::SpanIndex(start), parse::SpanIndex(end))| {
-            fmt.span.from_inner_byte_pos(start, end)
-        })
+        .map(|span| fmt.span.from_inner(*span))
         .collect();
 
     let mut cx = Context {
@@ -1044,7 +1041,9 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt<'_>,
                     let mut show_doc_note = false;
 
                     let mut suggestions = vec![];
-                    for sub in foreign::$kind::iter_subs(fmt_str) {
+                    // account for `"` and account for raw strings `r#`
+                    let padding = str_style.map(|i| i + 2).unwrap_or(1);
+                    for sub in foreign::$kind::iter_subs(fmt_str, padding) {
                         let trn = match sub.translate() {
                             Some(trn) => trn,
 
@@ -1064,10 +1063,8 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt<'_>,
                             show_doc_note = true;
                         }
 
-                        if let Some((start, end)) = pos {
-                            // account for `"` and account for raw strings `r#`
-                            let padding = str_style.map(|i| i + 2).unwrap_or(1);
-                            let sp = fmt_sp.from_inner_byte_pos(start + padding, end + padding);
+                        if let Some(inner_sp) = pos {
+                            let sp = fmt_sp.from_inner(inner_sp);
                             suggestions.push((sp, trn));
                         } else {
                             diag.help(&format!("`{}` should be written as `{}`", sub, trn));
diff --git a/src/libsyntax_ext/format_foreign.rs b/src/libsyntax_ext/format_foreign.rs
index 261b2f373ce..7ad5997bf2c 100644
--- a/src/libsyntax_ext/format_foreign.rs
+++ b/src/libsyntax_ext/format_foreign.rs
@@ -1,5 +1,6 @@
 pub mod printf {
     use super::strcursor::StrCursor as Cur;
+    use syntax_pos::InnerSpan;
 
     /// Represents a single `printf`-style substitution.
     #[derive(Clone, PartialEq, Debug)]
@@ -18,7 +19,7 @@ pub mod printf {
             }
         }
 
-        pub fn position(&self) -> Option<(usize, usize)> {
+        pub fn position(&self) -> Option<InnerSpan> {
             match *self {
                 Substitution::Format(ref fmt) => Some(fmt.position),
                 _ => None,
@@ -28,7 +29,7 @@ pub mod printf {
         pub fn set_position(&mut self, start: usize, end: usize) {
             match self {
                 Substitution::Format(ref mut fmt) => {
-                    fmt.position = (start, end);
+                    fmt.position = InnerSpan::new(start, end);
                 }
                 _ => {}
             }
@@ -65,7 +66,7 @@ pub mod printf {
         /// Type of parameter being converted.
         pub type_: &'a str,
         /// Byte offset for the start and end of this formatting directive.
-        pub position: (usize, usize),
+        pub position: InnerSpan,
     }
 
     impl Format<'_> {
@@ -263,10 +264,10 @@ pub mod printf {
     }
 
     /// Returns an iterator over all substitutions in a given string.
-    pub fn iter_subs(s: &str) -> Substitutions<'_> {
+    pub fn iter_subs(s: &str, start_pos: usize) -> Substitutions<'_> {
         Substitutions {
             s,
-            pos: 0,
+            pos: start_pos,
         }
     }
 
@@ -282,9 +283,9 @@ pub mod printf {
             let (mut sub, tail) = parse_next_substitution(self.s)?;
             self.s = tail;
             match sub {
-                Substitution::Format(_) => if let Some((start, end)) = sub.position() {
-                    sub.set_position(start + self.pos, end + self.pos);
-                    self.pos += end;
+                Substitution::Format(_) => if let Some(inner_span) = sub.position() {
+                    sub.set_position(inner_span.start + self.pos, inner_span.end + self.pos);
+                    self.pos += inner_span.end;
                 }
                 Substitution::Escape => self.pos += 2,
             }
@@ -373,7 +374,7 @@ pub mod printf {
                     precision: None,
                     length: None,
                     type_: at.slice_between(next).unwrap(),
-                    position: (start.at, next.at),
+                    position: InnerSpan::new(start.at, next.at),
                 }),
                 next.slice_after()
             ));
@@ -560,7 +561,7 @@ pub mod printf {
         drop(next);
 
         end = at;
-        let position = (start.at, end.at);
+        let position = InnerSpan::new(start.at, end.at);
 
         let f = Format {
             span: start.slice_between(end).unwrap(),
@@ -650,7 +651,7 @@ pub mod printf {
                                 precision: $prec,
                                 length: $len,
                                 type_: $type_,
-                                position: $pos,
+                                position: syntax_pos::InnerSpan::new($pos.0, $pos.1),
                             }),
                             "!"
                         ))
@@ -711,7 +712,7 @@ pub mod printf {
         #[test]
         fn test_iter() {
             let s = "The %d'th word %% is: `%.*s` %!\n";
-            let subs: Vec<_> = iter_subs(s).map(|sub| sub.translate()).collect();
+            let subs: Vec<_> = iter_subs(s, 0).map(|sub| sub.translate()).collect();
             assert_eq!(
                 subs.iter().map(|ms| ms.as_ref().map(|s| &s[..])).collect::<Vec<_>>(),
                 vec![Some("{}"), None, Some("{:.*}"), None]
@@ -761,6 +762,7 @@ pub mod printf {
 
 pub mod shell {
     use super::strcursor::StrCursor as Cur;
+    use syntax_pos::InnerSpan;
 
     #[derive(Clone, PartialEq, Debug)]
     pub enum Substitution<'a> {
@@ -778,11 +780,11 @@ pub mod shell {
             }
         }
 
-        pub fn position(&self) -> Option<(usize, usize)> {
+        pub fn position(&self) -> Option<InnerSpan> {
             match self {
                 Substitution::Ordinal(_, pos) |
                 Substitution::Name(_, pos) |
-                Substitution::Escape(pos) => Some(*pos),
+                Substitution::Escape(pos) => Some(InnerSpan::new(pos.0, pos.1)),
             }
         }
 
@@ -804,10 +806,10 @@ pub mod shell {
     }
 
     /// Returns an iterator over all substitutions in a given string.
-    pub fn iter_subs(s: &str) -> Substitutions<'_> {
+    pub fn iter_subs(s: &str, start_pos: usize) -> Substitutions<'_> {
         Substitutions {
             s,
-            pos: 0,
+            pos: start_pos,
         }
     }
 
@@ -823,7 +825,7 @@ pub mod shell {
             match parse_next_substitution(self.s) {
                 Some((mut sub, tail)) => {
                     self.s = tail;
-                    if let Some((start, end)) = sub.position() {
+                    if let Some(InnerSpan { start, end }) = sub.position() {
                         sub.set_position(start + self.pos, end + self.pos);
                         self.pos += end;
                     }
@@ -940,7 +942,7 @@ pub mod shell {
         fn test_iter() {
             use super::iter_subs;
             let s = "The $0'th word $$ is: `$WORD` $!\n";
-            let subs: Vec<_> = iter_subs(s).map(|sub| sub.translate()).collect();
+            let subs: Vec<_> = iter_subs(s, 0).map(|sub| sub.translate()).collect();
             assert_eq!(
                 subs.iter().map(|ms| ms.as_ref().map(|s| &s[..])).collect::<Vec<_>>(),
                 vec![Some("{0}"), None, Some("{WORD}")]
diff --git a/src/libsyntax_ext/trace_macros.rs b/src/libsyntax_ext/trace_macros.rs
index 6c74f77ff1f..512513e9b41 100644
--- a/src/libsyntax_ext/trace_macros.rs
+++ b/src/libsyntax_ext/trace_macros.rs
@@ -16,11 +16,11 @@ pub fn expand_trace_macros(cx: &mut ExtCtxt<'_>,
                                        feature_gate::EXPLAIN_TRACE_MACROS);
     }
 
-    match (tt.len(), tt.first()) {
-        (1, Some(TokenTree::Token(token))) if token.is_keyword(kw::True) => {
+    match tt {
+        [TokenTree::Token(token)] if token.is_keyword(kw::True) => {
             cx.set_trace_macros(true);
         }
-        (1, Some(TokenTree::Token(token))) if token.is_keyword(kw::False) => {
+        [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`"),
diff --git a/src/libsyntax_pos/lib.rs b/src/libsyntax_pos/lib.rs
index 649ab81198d..e7158372762 100644
--- a/src/libsyntax_pos/lib.rs
+++ b/src/libsyntax_pos/lib.rs
@@ -505,10 +505,10 @@ impl Span {
         )
     }
 
-    pub fn from_inner_byte_pos(self, start: usize, end: usize) -> Span {
+    pub fn from_inner(self, inner: InnerSpan) -> Span {
         let span = self.data();
-        Span::new(span.lo + BytePos::from_usize(start),
-                  span.lo + BytePos::from_usize(end),
+        Span::new(span.lo + BytePos::from_usize(inner.start),
+                  span.lo + BytePos::from_usize(inner.end),
                   span.ctxt)
     }
 
@@ -1396,6 +1396,18 @@ pub struct MalformedSourceMapPositions {
     pub end_pos: BytePos
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct InnerSpan {
+    pub start: usize,
+    pub end: usize,
+}
+
+impl InnerSpan {
+    pub fn new(start: usize, end: usize) -> InnerSpan {
+        InnerSpan { start, end }
+    }
+}
+
 // Given a slice of line start positions and a position, returns the index of
 // the line the position is on. Returns -1 if the position is located before
 // the first line.
diff --git a/src/libsyntax_pos/symbol.rs b/src/libsyntax_pos/symbol.rs
index 875c286bd8a..029685bcc24 100644
--- a/src/libsyntax_pos/symbol.rs
+++ b/src/libsyntax_pos/symbol.rs
@@ -203,6 +203,7 @@ symbols! {
         core_intrinsics,
         crate_id,
         crate_in_paths,
+        crate_local,
         crate_name,
         crate_type,
         crate_visibility_modifier,
@@ -221,6 +222,7 @@ symbols! {
         deref,
         deref_mut,
         derive,
+        direct,
         doc,
         doc_alias,
         doc_cfg,
@@ -278,8 +280,10 @@ symbols! {
         format_args_nl,
         from,
         From,
+        from_desugaring,
         from_error,
         from_generator,
+        from_method,
         from_ok,
         from_usize,
         fundamental,
@@ -443,6 +447,7 @@ symbols! {
         panic_impl,
         panic_implementation,
         panic_runtime,
+        parent_trait,
         partial_cmp,
         PartialOrd,
         passes,
@@ -569,6 +574,7 @@ symbols! {
         __rust_unstable_column,
         rvalue_static_promotion,
         sanitizer_runtime,
+        _Self,
         self_in_typedefs,
         self_struct_ctor,
         Send,