Merge branch 'master' into feature/core_convert_id

14 files changed, 151 insertions, 120 deletions

diff --git a/src/libstd/sys_common/at_exit_imp.rs b/src/libstd/sys_common/at_exit_imp.rs
index ce6fd4cb075..76e5df2c865 100644
--- a/src/libstd/sys_common/at_exit_imp.rs
+++ b/src/libstd/sys_common/at_exit_imp.rs
@@ -12,19 +12,24 @@
 //!
 //! Documentation can be found on the `rt::at_exit` function.
 
-use alloc::boxed::FnBox;
+use boxed::FnBox;
 use ptr;
+use mem;
 use sys_common::mutex::Mutex;
 
-type Queue = Vec<Box<FnBox()>>;
+type Queue = Vec<Box<dyn FnBox()>>;
 
 // NB these are specifically not types from `std::sync` as they currently rely
 // on poisoning and this module needs to operate at a lower level than requiring
 // the thread infrastructure to be in place (useful on the borders of
 // initialization/destruction).
+// We never call `LOCK.init()`, so it is UB to attempt to
+// acquire this mutex reentrantly!
 static LOCK: Mutex = Mutex::new();
 static mut QUEUE: *mut Queue = ptr::null_mut();
 
+const DONE: *mut Queue = 1_usize as *mut _;
+
 // The maximum number of times the cleanup routines will be run. While running
 // the at_exit closures new ones may be registered, and this count is the number
 // of times the new closures will be allowed to register successfully. After
@@ -35,7 +40,7 @@ unsafe fn init() -> bool {
     if QUEUE.is_null() {
         let state: Box<Queue> = box Vec::new();
         QUEUE = Box::into_raw(state);
-    } else if QUEUE as usize == 1 {
+    } else if QUEUE == DONE {
         // can't re-init after a cleanup
         return false
     }
@@ -44,20 +49,21 @@ unsafe fn init() -> bool {
 }
 
 pub fn cleanup() {
-    for i in 0..ITERS {
+    for i in 1..=ITERS {
         unsafe {
-            LOCK.lock();
-            let queue = QUEUE;
-            QUEUE = if i == ITERS - 1 {1} else {0} as *mut _;
-            LOCK.unlock();
+            let queue = {
+                let _guard = LOCK.lock();
+                mem::replace(&mut QUEUE, if i == ITERS { DONE } else { ptr::null_mut() })
+            };
 
             // make sure we're not recursively cleaning up
-            assert!(queue as usize != 1);
+            assert!(queue != DONE);
 
             // If we never called init, not need to cleanup!
-            if queue as usize != 0 {
+            if !queue.is_null() {
                 let queue: Box<Queue> = Box::from_raw(queue);
                 for to_run in *queue {
+                    // We are not holding any lock, so reentrancy is fine.
                     to_run();
                 }
             }
@@ -65,16 +71,16 @@ pub fn cleanup() {
     }
 }
 
-pub fn push(f: Box<FnBox()>) -> bool {
-    let mut ret = true;
+pub fn push(f: Box<dyn FnBox()>) -> bool {
     unsafe {
-        LOCK.lock();
+        let _guard = LOCK.lock();
         if init() {
+            // We are just moving `f` around, not calling it.
+            // There is no possibility of reentrancy here.
             (*QUEUE).push(f);
+            true
         } else {
-            ret = false;
+            false
         }
-        LOCK.unlock();
     }
-    ret
 }
diff --git a/src/libstd/sys_common/backtrace.rs b/src/libstd/sys_common/backtrace.rs
index 36cbce2df75..77371782977 100644
--- a/src/libstd/sys_common/backtrace.rs
+++ b/src/libstd/sys_common/backtrace.rs
@@ -41,13 +41,15 @@ pub struct Frame {
     pub exact_position: *const u8,
     /// Address of the enclosing function.
     pub symbol_addr: *const u8,
+    /// Which inlined function is this frame referring to
+    pub inline_context: u32,
 }
 
 /// Max number of frames to print.
 const MAX_NB_FRAMES: usize = 100;
 
 /// Prints the current backtrace.
-pub fn print(w: &mut Write, format: PrintFormat) -> io::Result<()> {
+pub fn print(w: &mut dyn Write, format: PrintFormat) -> io::Result<()> {
     static LOCK: Mutex = Mutex::new();
 
     // Use a lock to prevent mixed output in multithreading context.
@@ -60,10 +62,11 @@ pub fn print(w: &mut Write, format: PrintFormat) -> io::Result<()> {
     }
 }
 
-fn _print(w: &mut Write, format: PrintFormat) -> io::Result<()> {
+fn _print(w: &mut dyn Write, format: PrintFormat) -> io::Result<()> {
     let mut frames = [Frame {
         exact_position: ptr::null(),
         symbol_addr: ptr::null(),
+        inline_context: 0,
     }; MAX_NB_FRAMES];
     let (nb_frames, context) = unwind_backtrace(&mut frames)?;
     let (skipped_before, skipped_after) =
@@ -133,13 +136,13 @@ pub fn __rust_begin_short_backtrace<F, T>(f: F) -> T
     f()
 }
 
-/// Controls how the backtrace should be formated.
+/// Controls how the backtrace should be formatted.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum PrintFormat {
-    /// Show all the frames with absolute path for files.
-    Full = 2,
     /// Show only relevant data from the backtrace.
-    Short = 3,
+    Short = 2,
+    /// Show all the frames with absolute path for files.
+    Full = 3,
 }
 
 // For now logging is turned off by default, and this function checks to see
@@ -147,23 +150,21 @@ pub enum PrintFormat {
 pub fn log_enabled() -> Option<PrintFormat> {
     static ENABLED: atomic::AtomicIsize = atomic::AtomicIsize::new(0);
     match ENABLED.load(Ordering::SeqCst) {
-        0 => {},
+        0 => {}
         1 => return None,
-        2 => return Some(PrintFormat::Full),
-        3 => return Some(PrintFormat::Short),
-        _ => unreachable!(),
+        2 => return Some(PrintFormat::Short),
+        _ => return Some(PrintFormat::Full),
     }
 
-    let val = match env::var_os("RUST_BACKTRACE") {
-        Some(x) => if &x == "0" {
+    let val = env::var_os("RUST_BACKTRACE").and_then(|x|
+        if &x == "0" {
             None
         } else if &x == "full" {
             Some(PrintFormat::Full)
         } else {
             Some(PrintFormat::Short)
-        },
-        None => None,
-    };
+        }
+    );
     ENABLED.store(match val {
         Some(v) => v as isize,
         None => 1,
@@ -175,7 +176,7 @@ pub fn log_enabled() -> Option<PrintFormat> {
 ///
 /// These output functions should now be used everywhere to ensure consistency.
 /// You may want to also use `output_fileline`.
-fn output(w: &mut Write, idx: usize, frame: Frame,
+fn output(w: &mut dyn Write, idx: usize, frame: Frame,
               s: Option<&str>, format: PrintFormat) -> io::Result<()> {
     // Remove the `17: 0x0 - <unknown>` line.
     if format == PrintFormat::Short && frame.exact_position == ptr::null() {
@@ -200,7 +201,7 @@ fn output(w: &mut Write, idx: usize, frame: Frame,
 ///
 /// See also `output`.
 #[allow(dead_code)]
-fn output_fileline(w: &mut Write,
+fn output_fileline(w: &mut dyn Write,
                    file: &[u8],
                    line: u32,
                    format: PrintFormat) -> io::Result<()> {
@@ -252,7 +253,7 @@ fn output_fileline(w: &mut Write,
 // Note that this demangler isn't quite as fancy as it could be. We have lots
 // of other information in our symbols like hashes, version, type information,
 // etc. Additionally, this doesn't handle glue symbols at all.
-pub fn demangle(writer: &mut Write, mut s: &str, format: PrintFormat) -> io::Result<()> {
+pub fn demangle(writer: &mut dyn Write, mut s: &str, format: PrintFormat) -> io::Result<()> {
     // During ThinLTO LLVM may import and rename internal symbols, so strip out
     // those endings first as they're one of the last manglings applied to
     // symbol names.
@@ -261,7 +262,7 @@ pub fn demangle(writer: &mut Write, mut s: &str, format: PrintFormat) -> io::Res
         let candidate = &s[i + llvm.len()..];
         let all_hex = candidate.chars().all(|c| {
             match c {
-                'A' ... 'F' | '0' ... '9' => true,
+                'A' ..= 'F' | '0' ..= '9' => true,
                 _ => false,
             }
         });
diff --git a/src/libstd/sys_common/bytestring.rs b/src/libstd/sys_common/bytestring.rs
index eb9cad09915..971b83938c1 100644
--- a/src/libstd/sys_common/bytestring.rs
+++ b/src/libstd/sys_common/bytestring.rs
@@ -11,7 +11,7 @@
 #![allow(dead_code)]
 
 use fmt::{Formatter, Result, Write};
-use std_unicode::lossy::{Utf8Lossy, Utf8LossyChunk};
+use core::str::lossy::{Utf8Lossy, Utf8LossyChunk};
 
 pub fn debug_fmt_bytestring(slice: &[u8], f: &mut Formatter) -> Result {
     // Writes out a valid unicode string with the correct escape sequences
diff --git a/src/libstd/sys_common/mod.rs b/src/libstd/sys_common/mod.rs
index 27504d374dd..d0c4d6a7737 100644
--- a/src/libstd/sys_common/mod.rs
+++ b/src/libstd/sys_common/mod.rs
@@ -28,6 +28,16 @@
 use sync::Once;
 use sys;
 
+macro_rules! rtabort {
+    ($($t:tt)*) => (::sys_common::util::abort(format_args!($($t)*)))
+}
+
+macro_rules! rtassert {
+    ($e:expr) => (if !$e {
+        rtabort!(concat!("assertion failed: ", stringify!($e)));
+    })
+}
+
 pub mod at_exit_imp;
 #[cfg(feature = "backtrace")]
 pub mod backtrace;
@@ -101,10 +111,6 @@ pub fn at_exit<F: FnOnce() + Send + 'static>(f: F) -> Result<(), ()> {
     if at_exit_imp::push(Box::new(f)) {Ok(())} else {Err(())}
 }
 
-macro_rules! rtabort {
-    ($($t:tt)*) => (::sys_common::util::abort(format_args!($($t)*)))
-}
-
 /// One-time runtime cleanup.
 pub fn cleanup() {
     static CLEANUP: Once = Once::new();
diff --git a/src/libstd/sys_common/mutex.rs b/src/libstd/sys_common/mutex.rs
index d1a738770d3..c6d531c7a1a 100644
--- a/src/libstd/sys_common/mutex.rs
+++ b/src/libstd/sys_common/mutex.rs
@@ -24,11 +24,17 @@ impl Mutex {
     ///
     /// Behavior is undefined if the mutex is moved after it is
     /// first used with any of the functions below.
+    /// Also, until `init` is called, behavior is undefined if this
+    /// mutex is ever used reentrantly, i.e., `raw_lock` or `try_lock`
+    /// are called by the thread currently holding the lock.
     pub const fn new() -> Mutex { Mutex(imp::Mutex::new()) }
 
     /// Prepare the mutex for use.
     ///
     /// This should be called once the mutex is at a stable memory address.
+    /// If called, this must be the very first thing that happens to the mutex.
+    /// Calling it in parallel with or after any operation (including another
+    /// `init()`) is undefined behavior.
     #[inline]
     pub unsafe fn init(&mut self) { self.0.init() }
 
@@ -37,7 +43,15 @@ impl Mutex {
     /// Behavior is undefined if the mutex has been moved between this and any
     /// previous function call.
     #[inline]
-    pub unsafe fn lock(&self) { self.0.lock() }
+    pub unsafe fn raw_lock(&self) { self.0.lock() }
+
+    /// Calls raw_lock() and then returns an RAII guard to guarantee the mutex
+    /// will be unlocked.
+    #[inline]
+    pub unsafe fn lock(&self) -> MutexGuard {
+        self.raw_lock();
+        MutexGuard(&self.0)
+    }
 
     /// Attempts to lock the mutex without blocking, returning whether it was
     /// successfully acquired or not.
@@ -51,8 +65,11 @@ impl Mutex {
     ///
     /// Behavior is undefined if the current thread does not actually hold the
     /// mutex.
+    ///
+    /// Consider switching from the pair of raw_lock() and raw_unlock() to
+    /// lock() whenever possible.
     #[inline]
-    pub unsafe fn unlock(&self) { self.0.unlock() }
+    pub unsafe fn raw_unlock(&self) { self.0.unlock() }
 
     /// Deallocates all resources associated with this mutex.
     ///
@@ -64,3 +81,14 @@ impl Mutex {
 
 // not meant to be exported to the outside world, just the containing module
 pub fn raw(mutex: &Mutex) -> &imp::Mutex { &mutex.0 }
+
+#[must_use]
+/// A simple RAII utility for the above Mutex without the poisoning semantics.
+pub struct MutexGuard<'a>(&'a imp::Mutex);
+
+impl<'a> Drop for MutexGuard<'a> {
+    #[inline]
+    fn drop(&mut self) {
+        unsafe { self.0.unlock(); }
+    }
+}
diff --git a/src/libstd/sys_common/net.rs b/src/libstd/sys_common/net.rs
index c70b39995eb..b841afe1a51 100644
--- a/src/libstd/sys_common/net.rs
+++ b/src/libstd/sys_common/net.rs
@@ -166,27 +166,9 @@ pub fn lookup_host(host: &str) -> io::Result<LookupHost> {
     hints.ai_socktype = c::SOCK_STREAM;
     let mut res = ptr::null_mut();
     unsafe {
-        match cvt_gai(c::getaddrinfo(c_host.as_ptr(), ptr::null(), &hints, &mut res)) {
-            Ok(_) => {
-                Ok(LookupHost { original: res, cur: res })
-            },
-            #[cfg(unix)]
-            Err(e) => {
-                // If we're running glibc prior to version 2.26, the lookup
-                // failure could be caused by caching a stale /etc/resolv.conf.
-                // We need to call libc::res_init() to clear the cache. But we
-                // shouldn't call it in on any other platform, because other
-                // res_init implementations aren't thread-safe. See
-                // https://github.com/rust-lang/rust/issues/41570 and
-                // https://github.com/rust-lang/rust/issues/43592.
-                use sys::net::res_init_if_glibc_before_2_26;
-                let _ = res_init_if_glibc_before_2_26();
-                Err(e)
-            },
-            // the cfg is needed here to avoid an "unreachable pattern" warning
-            #[cfg(not(unix))]
-            Err(e) => Err(e),
-        }
+        cvt_gai(c::getaddrinfo(c_host.as_ptr(), ptr::null(), &hints, &mut res)).map(|_| {
+            LookupHost { original: res, cur: res }
+        })
     }
 }
 
diff --git a/src/libstd/sys_common/poison.rs b/src/libstd/sys_common/poison.rs
index 934ac3edbf1..1625efe4a2a 100644
--- a/src/libstd/sys_common/poison.rs
+++ b/src/libstd/sys_common/poison.rs
@@ -98,7 +98,7 @@ pub struct PoisonError<T> {
 }
 
 /// An enumeration of possible errors associated with a [`TryLockResult`] which
-/// can occur while trying to aquire a lock, from the [`try_lock`] method on a
+/// can occur while trying to acquire a lock, from the [`try_lock`] method on a
 /// [`Mutex`] or the [`try_read`] and [`try_write`] methods on an [`RwLock`].
 ///
 /// [`Mutex`]: struct.Mutex.html
@@ -251,7 +251,7 @@ impl<T> Error for TryLockError<T> {
         }
     }
 
-    fn cause(&self) -> Option<&Error> {
+    fn cause(&self) -> Option<&dyn Error> {
         match *self {
             TryLockError::Poisoned(ref p) => Some(p),
             _ => None
diff --git a/src/libstd/sys_common/process.rs b/src/libstd/sys_common/process.rs
index fd1a5fdb410..ddf0ebe603e 100644
--- a/src/libstd/sys_common/process.rs
+++ b/src/libstd/sys_common/process.rs
@@ -14,7 +14,7 @@
 use ffi::{OsStr, OsString};
 use env;
 use collections::BTreeMap;
-use alloc::borrow::Borrow;
+use borrow::Borrow;
 
 pub trait EnvKey:
     From<OsString> + Into<OsString> +
@@ -47,6 +47,7 @@ impl EnvKey for DefaultEnvKey {}
 #[derive(Clone, Debug)]
 pub struct CommandEnv<K> {
     clear: bool,
+    saw_path: bool,
     vars: BTreeMap<K, Option<OsString>>
 }
 
@@ -54,6 +55,7 @@ impl<K: EnvKey> Default for CommandEnv<K> {
     fn default() -> Self {
         CommandEnv {
             clear: false,
+            saw_path: false,
             vars: Default::default()
         }
     }
@@ -108,9 +110,11 @@ impl<K: EnvKey> CommandEnv<K> {
 
     // The following functions build up changes
     pub fn set(&mut self, key: &OsStr, value: &OsStr) {
+        self.maybe_saw_path(&key);
         self.vars.insert(key.to_owned().into(), Some(value.to_owned()));
     }
     pub fn remove(&mut self, key: &OsStr) {
+        self.maybe_saw_path(&key);
         if self.clear {
             self.vars.remove(key);
         } else {
@@ -121,4 +125,12 @@ impl<K: EnvKey> CommandEnv<K> {
         self.clear = true;
         self.vars.clear();
     }
+    pub fn have_changed_path(&self) -> bool {
+        self.saw_path || self.clear
+    }
+    fn maybe_saw_path(&mut self, key: &OsStr) {
+        if !self.saw_path && key == "PATH" {
+            self.saw_path = true;
+        }
+    }
 }
diff --git a/src/libstd/sys_common/remutex.rs b/src/libstd/sys_common/remutex.rs
index ce43ec6d9ab..071a3a25c7a 100644
--- a/src/libstd/sys_common/remutex.rs
+++ b/src/libstd/sys_common/remutex.rs
@@ -13,6 +13,7 @@ use marker;
 use ops::Deref;
 use sys_common::poison::{self, TryLockError, TryLockResult, LockResult};
 use sys::mutex as sys;
+use panic::{UnwindSafe, RefUnwindSafe};
 
 /// A re-entrant mutual exclusion
 ///
@@ -28,6 +29,9 @@ pub struct ReentrantMutex<T> {
 unsafe impl<T: Send> Send for ReentrantMutex<T> {}
 unsafe impl<T: Send> Sync for ReentrantMutex<T> {}
 
+impl<T> UnwindSafe for ReentrantMutex<T> {}
+impl<T> RefUnwindSafe for ReentrantMutex<T> {}
+
 
 /// An RAII implementation of a "scoped lock" of a mutex. When this structure is
 /// dropped (falls out of scope), the lock will be unlocked.
@@ -41,7 +45,7 @@ unsafe impl<T: Send> Sync for ReentrantMutex<T> {}
 /// because implementation of the trait would violate Rust’s reference aliasing
 /// rules. Use interior mutability (usually `RefCell`) in order to mutate the
 /// guarded data.
-#[must_use]
+#[must_use = "if unused the ReentrantMutex will immediately unlock"]
 pub struct ReentrantMutexGuard<'a, T: 'a> {
     // funny underscores due to how Deref currently works (it disregards field
     // privacy).
diff --git a/src/libstd/sys_common/thread.rs b/src/libstd/sys_common/thread.rs
index f1379b6ec63..86a5e2b8694 100644
--- a/src/libstd/sys_common/thread.rs
+++ b/src/libstd/sys_common/thread.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use alloc::boxed::FnBox;
+use boxed::FnBox;
 use env;
 use sync::atomic::{self, Ordering};
 use sys::stack_overflow;
@@ -21,7 +21,7 @@ pub unsafe fn start_thread(main: *mut u8) {
     let _handler = stack_overflow::Handler::new();
 
     // Finally, let's run some code.
-    Box::from_raw(main as *mut Box<FnBox()>)()
+    Box::from_raw(main as *mut Box<dyn FnBox()>)()
 }
 
 pub fn min_stack() -> usize {
diff --git a/src/libstd/sys_common/thread_info.rs b/src/libstd/sys_common/thread_info.rs
index 7970042b1d6..d75cbded734 100644
--- a/src/libstd/sys_common/thread_info.rs
+++ b/src/libstd/sys_common/thread_info.rs
@@ -11,10 +11,11 @@
 #![allow(dead_code)] // stack_guard isn't used right now on all platforms
 
 use cell::RefCell;
+use sys::thread::guard::Guard;
 use thread::Thread;
 
 struct ThreadInfo {
-    stack_guard: Option<usize>,
+    stack_guard: Option<Guard>,
     thread: Thread,
 }
 
@@ -38,14 +39,18 @@ pub fn current_thread() -> Option<Thread> {
     ThreadInfo::with(|info| info.thread.clone())
 }
 
-pub fn stack_guard() -> Option<usize> {
-    ThreadInfo::with(|info| info.stack_guard).and_then(|o| o)
+pub fn stack_guard() -> Option<Guard> {
+    ThreadInfo::with(|info| info.stack_guard.clone()).and_then(|o| o)
 }
 
-pub fn set(stack_guard: Option<usize>, thread: Thread) {
+pub fn set(stack_guard: Option<Guard>, thread: Thread) {
     THREAD_INFO.with(|c| assert!(c.borrow().is_none()));
     THREAD_INFO.with(move |c| *c.borrow_mut() = Some(ThreadInfo{
         stack_guard,
         thread,
     }));
 }
+
+pub fn reset_guard(stack_guard: Option<Guard>) {
+    THREAD_INFO.with(move |c| c.borrow_mut().as_mut().unwrap().stack_guard = stack_guard);
+}
diff --git a/src/libstd/sys_common/thread_local.rs b/src/libstd/sys_common/thread_local.rs
index a4aa3d96d25..bb72cb0930a 100644
--- a/src/libstd/sys_common/thread_local.rs
+++ b/src/libstd/sys_common/thread_local.rs
@@ -161,15 +161,16 @@ impl StaticKey {
         // Additionally a 0-index of a tls key hasn't been seen on windows, so
         // we just simplify the whole branch.
         if imp::requires_synchronized_create() {
+            // We never call `INIT_LOCK.init()`, so it is UB to attempt to
+            // acquire this mutex reentrantly!
             static INIT_LOCK: Mutex = Mutex::new();
-            INIT_LOCK.lock();
+            let _guard = INIT_LOCK.lock();
             let mut key = self.key.load(Ordering::SeqCst);
             if key == 0 {
                 key = imp::create(self.dtor) as usize;
                 self.key.store(key, Ordering::SeqCst);
             }
-            INIT_LOCK.unlock();
-            assert!(key != 0);
+            rtassert!(key != 0);
             return key
         }
 
@@ -190,7 +191,7 @@ impl StaticKey {
             imp::destroy(key1);
             key2
         };
-        assert!(key != 0);
+        rtassert!(key != 0);
         match self.key.compare_and_swap(0, key as usize, Ordering::SeqCst) {
             // The CAS succeeded, so we've created the actual key
             0 => key as usize,
diff --git a/src/libstd/sys_common/util.rs b/src/libstd/sys_common/util.rs
index a391c7cc6ef..a373e980b97 100644
--- a/src/libstd/sys_common/util.rs
+++ b/src/libstd/sys_common/util.rs
@@ -10,10 +10,13 @@
 
 use fmt;
 use io::prelude::*;
-use sys::stdio::Stderr;
+use sys::stdio::{Stderr, stderr_prints_nothing};
 use thread;
 
 pub fn dumb_print(args: fmt::Arguments) {
+    if stderr_prints_nothing() {
+        return
+    }
     let _ = Stderr::new().map(|mut stderr| stderr.write_fmt(args));
 }
 
diff --git a/src/libstd/sys_common/wtf8.rs b/src/libstd/sys_common/wtf8.rs
index 46d554d6411..45204b56ead 100644
--- a/src/libstd/sys_common/wtf8.rs
+++ b/src/libstd/sys_common/wtf8.rs
@@ -27,7 +27,6 @@
 
 use core::str::next_code_point;
 
-use ascii::*;
 use borrow::Cow;
 use char;
 use fmt;
@@ -57,7 +56,7 @@ pub struct CodePoint {
 /// Example: `U+1F4A9`
 impl fmt::Debug for CodePoint {
     #[inline]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         write!(formatter, "U+{:04X}", self.value)
     }
 }
@@ -77,7 +76,7 @@ impl CodePoint {
     #[inline]
     pub fn from_u32(value: u32) -> Option<CodePoint> {
         match value {
-            0 ... 0x10FFFF => Some(CodePoint { value: value }),
+            0 ..= 0x10FFFF => Some(CodePoint { value: value }),
             _ => None
         }
     }
@@ -102,7 +101,7 @@ impl CodePoint {
     #[inline]
     pub fn to_char(&self) -> Option<char> {
         match self.value {
-            0xD800 ... 0xDFFF => None,
+            0xD800 ..= 0xDFFF => None,
             _ => Some(unsafe { char::from_u32_unchecked(self.value) })
         }
     }
@@ -145,7 +144,7 @@ impl ops::DerefMut for Wtf8Buf {
 /// Example: `"a\u{D800}"` for a string with code points [U+0061, U+D800]
 impl fmt::Debug for Wtf8Buf {
     #[inline]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         fmt::Debug::fmt(&**self, formatter)
     }
 }
@@ -254,6 +253,11 @@ impl Wtf8Buf {
         self.bytes.shrink_to_fit()
     }
 
+    #[inline]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.bytes.shrink_to(min_capacity)
+    }
+
     /// Returns the number of bytes that this string buffer can hold without reallocating.
     #[inline]
     pub fn capacity(&self) -> usize {
@@ -301,7 +305,7 @@ impl Wtf8Buf {
     /// like concatenating ill-formed UTF-16 strings effectively would.
     #[inline]
     pub fn push(&mut self, code_point: CodePoint) {
-        if let trail @ 0xDC00...0xDFFF = code_point.to_u32() {
+        if let trail @ 0xDC00..=0xDFFF = code_point.to_u32() {
             if let Some(lead) = (&*self).final_lead_surrogate() {
                 let len_without_lead_surrogate = self.len() - 3;
                 self.bytes.truncate(len_without_lead_surrogate);
@@ -428,20 +432,15 @@ impl fmt::Debug for Wtf8 {
 
         formatter.write_str("\"")?;
         let mut pos = 0;
-        loop {
-            match self.next_surrogate(pos) {
-                None => break,
-                Some((surrogate_pos, surrogate)) => {
-                    write_str_escaped(
-                        formatter,
-                        unsafe { str::from_utf8_unchecked(
-                            &self.bytes[pos .. surrogate_pos]
-                        )},
-                    )?;
-                    write!(formatter, "\\u{{{:x}}}", surrogate)?;
-                    pos = surrogate_pos + 3;
-                }
-            }
+        while let Some((surrogate_pos, surrogate)) = self.next_surrogate(pos) {
+            write_str_escaped(
+                formatter,
+                unsafe { str::from_utf8_unchecked(
+                    &self.bytes[pos .. surrogate_pos]
+                )},
+            )?;
+            write!(formatter, "\\u{{{:x}}}", surrogate)?;
+            pos = surrogate_pos + 3;
         }
         write_str_escaped(
             formatter,
@@ -526,7 +525,7 @@ impl Wtf8 {
     #[inline]
     pub fn ascii_byte_at(&self, position: usize) -> u8 {
         match self.bytes[position] {
-            ascii_byte @ 0x00 ... 0x7F => ascii_byte,
+            ascii_byte @ 0x00 ..= 0x7F => ascii_byte,
             _ => 0xFF
         }
     }
@@ -631,7 +630,7 @@ impl Wtf8 {
             return None
         }
         match &self.bytes[(len - 3)..] {
-            &[0xED, b2 @ 0xA0...0xAF, b3] => Some(decode_surrogate(b2, b3)),
+            &[0xED, b2 @ 0xA0..=0xAF, b3] => Some(decode_surrogate(b2, b3)),
             _ => None
         }
     }
@@ -643,7 +642,7 @@ impl Wtf8 {
             return None
         }
         match &self.bytes[..3] {
-            &[0xED, b2 @ 0xB0...0xBF, b3] => Some(decode_surrogate(b2, b3)),
+            &[0xED, b2 @ 0xB0..=0xBF, b3] => Some(decode_surrogate(b2, b3)),
             _ => None
         }
     }
@@ -876,24 +875,8 @@ impl Hash for Wtf8 {
     }
 }
 
-impl AsciiExt for Wtf8 {
-    type Owned = Wtf8Buf;
-
-    fn is_ascii(&self) -> bool {
-        self.bytes.is_ascii()
-    }
-    fn to_ascii_uppercase(&self) -> Wtf8Buf {
-        Wtf8Buf { bytes: self.bytes.to_ascii_uppercase() }
-    }
-    fn to_ascii_lowercase(&self) -> Wtf8Buf {
-        Wtf8Buf { bytes: self.bytes.to_ascii_lowercase() }
-    }
-    fn eq_ignore_ascii_case(&self, other: &Wtf8) -> bool {
-        self.bytes.eq_ignore_ascii_case(&other.bytes)
-    }
-
-    fn make_ascii_uppercase(&mut self) { self.bytes.make_ascii_uppercase() }
-    fn make_ascii_lowercase(&mut self) { self.bytes.make_ascii_lowercase() }
+impl Wtf8 {
+    pub fn make_ascii_uppercase(&mut self) { self.bytes.make_ascii_uppercase() }
 }
 
 #[cfg(test)]
@@ -1262,7 +1245,7 @@ mod tests {
     #[test]
     fn wtf8_display() {
         fn d(b: &[u8]) -> String {
-            format!("{}", &unsafe { Wtf8::from_bytes_unchecked(b) })
+            (&unsafe { Wtf8::from_bytes_unchecked(b) }).to_string()
         }
 
         assert_eq!("", d("".as_bytes()));