Update for Rust nightly 2018-04-19

50 files changed, 2346 insertions, 2112 deletions

diff --git a/ctr-std/src/alloc.rs b/ctr-std/src/alloc.rs
new file mode 100644
index 0000000..ff578ec
--- /dev/null
+++ b/ctr-std/src/alloc.rs
@@ -0,0 +1,121 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! dox
+
+#![unstable(issue = "32838", feature = "allocator_api")]
+
+#[doc(inline)] #[allow(deprecated)] pub use alloc_crate::alloc::Heap;
+#[doc(inline)] pub use alloc_crate::alloc::Global;
+#[doc(inline)] pub use alloc_system::System;
+#[doc(inline)] pub use core::alloc::*;
+
+#[cfg(not(test))]
+#[doc(hidden)]
+#[allow(unused_attributes)]
+pub mod __default_lib_allocator {
+    use super::{System, Layout, GlobalAlloc, Opaque};
+    // for symbol names src/librustc/middle/allocator.rs
+    // for signatures src/librustc_allocator/lib.rs
+
+    // linkage directives are provided as part of the current compiler allocator
+    // ABI
+
+    #[no_mangle]
+    #[rustc_std_internal_symbol]
+    pub unsafe extern fn __rdl_alloc(size: usize, align: usize) -> *mut u8 {
+        let layout = Layout::from_size_align_unchecked(size, align);
+        System.alloc(layout) as *mut u8
+    }
+
+    #[no_mangle]
+    #[rustc_std_internal_symbol]
+    pub unsafe extern fn __rdl_oom() -> ! {
+        System.oom()
+    }
+
+    #[no_mangle]
+    #[rustc_std_internal_symbol]
+    pub unsafe extern fn __rdl_dealloc(ptr: *mut u8,
+                                       size: usize,
+                                       align: usize) {
+        System.dealloc(ptr as *mut Opaque, Layout::from_size_align_unchecked(size, align))
+    }
+
+    #[no_mangle]
+    #[rustc_std_internal_symbol]
+    pub unsafe extern fn __rdl_realloc(ptr: *mut u8,
+                                       old_size: usize,
+                                       align: usize,
+                                       new_size: usize) -> *mut u8 {
+        let old_layout = Layout::from_size_align_unchecked(old_size, align);
+        System.realloc(ptr as *mut Opaque, old_layout, new_size) as *mut u8
+    }
+
+    #[no_mangle]
+    #[rustc_std_internal_symbol]
+    pub unsafe extern fn __rdl_alloc_zeroed(size: usize, align: usize) -> *mut u8 {
+        let layout = Layout::from_size_align_unchecked(size, align);
+        System.alloc_zeroed(layout) as *mut u8
+    }
+
+    #[cfg(stage0)]
+    pub mod stage0 {
+        #[no_mangle]
+        #[rustc_std_internal_symbol]
+        pub unsafe extern fn __rdl_usable_size(_layout: *const u8,
+                                               _min: *mut usize,
+                                               _max: *mut usize) {
+            unimplemented!()
+        }
+
+        #[no_mangle]
+        #[rustc_std_internal_symbol]
+        pub unsafe extern fn __rdl_alloc_excess(_size: usize,
+                                                _align: usize,
+                                                _excess: *mut usize,
+                                                _err: *mut u8) -> *mut u8 {
+            unimplemented!()
+        }
+
+        #[no_mangle]
+        #[rustc_std_internal_symbol]
+        pub unsafe extern fn __rdl_realloc_excess(_ptr: *mut u8,
+                                                  _old_size: usize,
+                                                  _old_align: usize,
+                                                  _new_size: usize,
+                                                  _new_align: usize,
+                                                  _excess: *mut usize,
+                                                  _err: *mut u8) -> *mut u8 {
+            unimplemented!()
+        }
+
+        #[no_mangle]
+        #[rustc_std_internal_symbol]
+        pub unsafe extern fn __rdl_grow_in_place(_ptr: *mut u8,
+                                                 _old_size: usize,
+                                                 _old_align: usize,
+                                                 _new_size: usize,
+                                                 _new_align: usize) -> u8 {
+            unimplemented!()
+        }
+
+        #[no_mangle]
+        #[rustc_std_internal_symbol]
+        pub unsafe extern fn __rdl_shrink_in_place(_ptr: *mut u8,
+                                                   _old_size: usize,
+                                                   _old_align: usize,
+                                                   _new_size: usize,
+                                                   _new_align: usize) -> u8 {
+            unimplemented!()
+        }
+
+    }
+}
diff --git a/ctr-std/src/ascii.rs b/ctr-std/src/ascii.rs
index 82e1a34..6472edb 100644
--- a/ctr-std/src/ascii.rs
+++ b/ctr-std/src/ascii.rs
@@ -26,9 +26,8 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use fmt;
-use ops::Range;
-use iter::FusedIterator;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use core::ascii::{EscapeDefault, escape_default};
 
 /// Extension methods for ASCII-subset only operations.
 ///
@@ -53,6 +52,7 @@ use iter::FusedIterator;
 ///
 /// [combining character]: https://en.wikipedia.org/wiki/Combining_character
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
 pub trait AsciiExt {
     /// Container type for copied ASCII characters.
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -85,6 +85,7 @@ pub trait AsciiExt {
     /// [`make_ascii_uppercase`]: #tymethod.make_ascii_uppercase
     /// [`str::to_uppercase`]: ../primitive.str.html#method.to_uppercase
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[allow(deprecated)]
     fn to_ascii_uppercase(&self) -> Self::Owned;
 
     /// Makes a copy of the value in its ASCII lower case equivalent.
@@ -105,6 +106,7 @@ pub trait AsciiExt {
     /// [`make_ascii_lowercase`]: #tymethod.make_ascii_lowercase
     /// [`str::to_lowercase`]: ../primitive.str.html#method.to_lowercase
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[allow(deprecated)]
     fn to_ascii_lowercase(&self) -> Self::Owned;
 
     /// Checks that two values are an ASCII case-insensitive match.
@@ -163,6 +165,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_alphabetic(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII uppercase character:
@@ -175,6 +178,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_uppercase(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII lowercase character:
@@ -187,6 +191,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_lowercase(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII alphanumeric character:
@@ -200,6 +205,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_alphanumeric(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII decimal digit:
@@ -212,6 +218,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_digit(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII hexadecimal digit:
@@ -225,6 +232,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_hexdigit(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII punctuation character:
@@ -242,10 +250,11 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_punctuation(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII graphic character:
-    /// U+0021 '@' ... U+007E '~'.
+    /// U+0021 '!' ... U+007E '~'.
     /// For strings, true if all characters in the string are
     /// ASCII graphic characters.
     ///
@@ -254,6 +263,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_graphic(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII whitespace character:
@@ -283,6 +293,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_whitespace(&self) -> bool { unimplemented!(); }
 
     /// Checks if the value is an ASCII control character:
@@ -295,6 +306,7 @@ pub trait AsciiExt {
     /// This method will be deprecated in favor of the identically-named
     /// inherent methods on `u8`, `char`, `[u8]` and `str`.
     #[unstable(feature = "ascii_ctype", issue = "39658")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use inherent methods instead")]
     fn is_ascii_control(&self) -> bool { unimplemented!(); }
 }
 
@@ -355,6 +367,7 @@ macro_rules! delegating_ascii_ctype_methods {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[allow(deprecated)]
 impl AsciiExt for u8 {
     type Owned = u8;
 
@@ -363,6 +376,7 @@ impl AsciiExt for u8 {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[allow(deprecated)]
 impl AsciiExt for char {
     type Owned = char;
 
@@ -371,6 +385,7 @@ impl AsciiExt for char {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[allow(deprecated)]
 impl AsciiExt for [u8] {
     type Owned = Vec<u8>;
 
@@ -428,6 +443,7 @@ impl AsciiExt for [u8] {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[allow(deprecated)]
 impl AsciiExt for str {
     type Owned = String;
 
@@ -483,477 +499,3 @@ impl AsciiExt for str {
         self.bytes().all(|b| b.is_ascii_control())
     }
 }
-
-/// An iterator over the escaped version of a byte.
-///
-/// This `struct` is created by the [`escape_default`] function. See its
-/// documentation for more.
-///
-/// [`escape_default`]: fn.escape_default.html
-#[stable(feature = "rust1", since = "1.0.0")]
-pub struct EscapeDefault {
-    range: Range<usize>,
-    data: [u8; 4],
-}
-
-/// Returns an iterator that produces an escaped version of a `u8`.
-///
-/// The default is chosen with a bias toward producing literals that are
-/// legal in a variety of languages, including C++11 and similar C-family
-/// languages. The exact rules are:
-///
-/// - Tab, CR and LF are escaped as '\t', '\r' and '\n' respectively.
-/// - Single-quote, double-quote and backslash chars are backslash-escaped.
-/// - Any other chars in the range [0x20,0x7e] are not escaped.
-/// - Any other chars are given hex escapes of the form '\xNN'.
-/// - Unicode escapes are never generated by this function.
-///
-/// # Examples
-///
-/// ```
-/// use std::ascii;
-///
-/// let escaped = ascii::escape_default(b'0').next().unwrap();
-/// assert_eq!(b'0', escaped);
-///
-/// let mut escaped = ascii::escape_default(b'\t');
-///
-/// assert_eq!(b'\\', escaped.next().unwrap());
-/// assert_eq!(b't', escaped.next().unwrap());
-///
-/// let mut escaped = ascii::escape_default(b'\r');
-///
-/// assert_eq!(b'\\', escaped.next().unwrap());
-/// assert_eq!(b'r', escaped.next().unwrap());
-///
-/// let mut escaped = ascii::escape_default(b'\n');
-///
-/// assert_eq!(b'\\', escaped.next().unwrap());
-/// assert_eq!(b'n', escaped.next().unwrap());
-///
-/// let mut escaped = ascii::escape_default(b'\'');
-///
-/// assert_eq!(b'\\', escaped.next().unwrap());
-/// assert_eq!(b'\'', escaped.next().unwrap());
-///
-/// let mut escaped = ascii::escape_default(b'"');
-///
-/// assert_eq!(b'\\', escaped.next().unwrap());
-/// assert_eq!(b'"', escaped.next().unwrap());
-///
-/// let mut escaped = ascii::escape_default(b'\\');
-///
-/// assert_eq!(b'\\', escaped.next().unwrap());
-/// assert_eq!(b'\\', escaped.next().unwrap());
-///
-/// let mut escaped = ascii::escape_default(b'\x9d');
-///
-/// assert_eq!(b'\\', escaped.next().unwrap());
-/// assert_eq!(b'x', escaped.next().unwrap());
-/// assert_eq!(b'9', escaped.next().unwrap());
-/// assert_eq!(b'd', escaped.next().unwrap());
-/// ```
-#[stable(feature = "rust1", since = "1.0.0")]
-pub fn escape_default(c: u8) -> EscapeDefault {
-    let (data, len) = match c {
-        b'\t' => ([b'\\', b't', 0, 0], 2),
-        b'\r' => ([b'\\', b'r', 0, 0], 2),
-        b'\n' => ([b'\\', b'n', 0, 0], 2),
-        b'\\' => ([b'\\', b'\\', 0, 0], 2),
-        b'\'' => ([b'\\', b'\'', 0, 0], 2),
-        b'"' => ([b'\\', b'"', 0, 0], 2),
-        b'\x20' ... b'\x7e' => ([c, 0, 0, 0], 1),
-        _ => ([b'\\', b'x', hexify(c >> 4), hexify(c & 0xf)], 4),
-    };
-
-    return EscapeDefault { range: (0.. len), data: data };
-
-    fn hexify(b: u8) -> u8 {
-        match b {
-            0 ... 9 => b'0' + b,
-            _ => b'a' + b - 10,
-        }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl Iterator for EscapeDefault {
-    type Item = u8;
-    fn next(&mut self) -> Option<u8> { self.range.next().map(|i| self.data[i]) }
-    fn size_hint(&self) -> (usize, Option<usize>) { self.range.size_hint() }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl DoubleEndedIterator for EscapeDefault {
-    fn next_back(&mut self) -> Option<u8> {
-        self.range.next_back().map(|i| self.data[i])
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl ExactSizeIterator for EscapeDefault {}
-#[unstable(feature = "fused", issue = "35602")]
-impl FusedIterator for EscapeDefault {}
-
-#[stable(feature = "std_debug", since = "1.16.0")]
-impl fmt::Debug for EscapeDefault {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.pad("EscapeDefault { .. }")
-    }
-}
-
-
-#[cfg(test)]
-mod tests {
-    //! Note that most of these tests are not testing `AsciiExt` methods, but
-    //! test inherent ascii methods of char, u8, str and [u8]. `AsciiExt` is
-    //! just using those methods, though.
-    use super::AsciiExt;
-    use char::from_u32;
-
-    #[test]
-    fn test_is_ascii() {
-        assert!(b"".is_ascii());
-        assert!(b"banana\0\x7F".is_ascii());
-        assert!(b"banana\0\x7F".iter().all(|b| b.is_ascii()));
-        assert!(!b"Vi\xe1\xbb\x87t Nam".is_ascii());
-        assert!(!b"Vi\xe1\xbb\x87t Nam".iter().all(|b| b.is_ascii()));
-        assert!(!b"\xe1\xbb\x87".iter().any(|b| b.is_ascii()));
-
-        assert!("".is_ascii());
-        assert!("banana\0\u{7F}".is_ascii());
-        assert!("banana\0\u{7F}".chars().all(|c| c.is_ascii()));
-        assert!(!"ประเทศไทย中华Việt Nam".chars().all(|c| c.is_ascii()));
-        assert!(!"ประเทศไทย中华ệ ".chars().any(|c| c.is_ascii()));
-    }
-
-    #[test]
-    fn test_to_ascii_uppercase() {
-        assert_eq!("url()URL()uRl()ürl".to_ascii_uppercase(), "URL()URL()URL()üRL");
-        assert_eq!("hıKß".to_ascii_uppercase(), "HıKß");
-
-        for i in 0..501 {
-            let upper = if 'a' as u32 <= i && i <= 'z' as u32 { i + 'A' as u32 - 'a' as u32 }
-                        else { i };
-            assert_eq!((from_u32(i).unwrap()).to_string().to_ascii_uppercase(),
-                       (from_u32(upper).unwrap()).to_string());
-        }
-    }
-
-    #[test]
-    fn test_to_ascii_lowercase() {
-        assert_eq!("url()URL()uRl()Ürl".to_ascii_lowercase(), "url()url()url()Ürl");
-        // Dotted capital I, Kelvin sign, Sharp S.
-        assert_eq!("HİKß".to_ascii_lowercase(), "hİKß");
-
-        for i in 0..501 {
-            let lower = if 'A' as u32 <= i && i <= 'Z' as u32 { i + 'a' as u32 - 'A' as u32 }
-                        else { i };
-            assert_eq!((from_u32(i).unwrap()).to_string().to_ascii_lowercase(),
-                       (from_u32(lower).unwrap()).to_string());
-        }
-    }
-
-    #[test]
-    fn test_make_ascii_lower_case() {
-        macro_rules! test {
-            ($from: expr, $to: expr) => {
-                {
-                    let mut x = $from;
-                    x.make_ascii_lowercase();
-                    assert_eq!(x, $to);
-                }
-            }
-        }
-        test!(b'A', b'a');
-        test!(b'a', b'a');
-        test!(b'!', b'!');
-        test!('A', 'a');
-        test!('À', 'À');
-        test!('a', 'a');
-        test!('!', '!');
-        test!(b"H\xc3\x89".to_vec(), b"h\xc3\x89");
-        test!("HİKß".to_string(), "hİKß");
-    }
-
-
-    #[test]
-    fn test_make_ascii_upper_case() {
-        macro_rules! test {
-            ($from: expr, $to: expr) => {
-                {
-                    let mut x = $from;
-                    x.make_ascii_uppercase();
-                    assert_eq!(x, $to);
-                }
-            }
-        }
-        test!(b'a', b'A');
-        test!(b'A', b'A');
-        test!(b'!', b'!');
-        test!('a', 'A');
-        test!('à', 'à');
-        test!('A', 'A');
-        test!('!', '!');
-        test!(b"h\xc3\xa9".to_vec(), b"H\xc3\xa9");
-        test!("hıKß".to_string(), "HıKß");
-
-        let mut x = "Hello".to_string();
-        x[..3].make_ascii_uppercase();  // Test IndexMut on String.
-        assert_eq!(x, "HELlo")
-    }
-
-    #[test]
-    fn test_eq_ignore_ascii_case() {
-        assert!("url()URL()uRl()Ürl".eq_ignore_ascii_case("url()url()url()Ürl"));
-        assert!(!"Ürl".eq_ignore_ascii_case("ürl"));
-        // Dotted capital I, Kelvin sign, Sharp S.
-        assert!("HİKß".eq_ignore_ascii_case("hİKß"));
-        assert!(!"İ".eq_ignore_ascii_case("i"));
-        assert!(!"K".eq_ignore_ascii_case("k"));
-        assert!(!"ß".eq_ignore_ascii_case("s"));
-
-        for i in 0..501 {
-            let lower = if 'A' as u32 <= i && i <= 'Z' as u32 { i + 'a' as u32 - 'A' as u32 }
-                        else { i };
-            assert!((from_u32(i).unwrap()).to_string().eq_ignore_ascii_case(
-                    &from_u32(lower).unwrap().to_string()));
-        }
-    }
-
-    #[test]
-    fn inference_works() {
-        let x = "a".to_string();
-        x.eq_ignore_ascii_case("A");
-    }
-
-    // Shorthands used by the is_ascii_* tests.
-    macro_rules! assert_all {
-        ($what:ident, $($str:tt),+) => {{
-            $(
-                for b in $str.chars() {
-                    if !b.$what() {
-                        panic!("expected {}({}) but it isn't",
-                               stringify!($what), b);
-                    }
-                }
-                for b in $str.as_bytes().iter() {
-                    if !b.$what() {
-                        panic!("expected {}(0x{:02x})) but it isn't",
-                               stringify!($what), b);
-                    }
-                }
-                assert!($str.$what());
-                assert!($str.as_bytes().$what());
-            )+
-        }};
-        ($what:ident, $($str:tt),+,) => (assert_all!($what,$($str),+))
-    }
-    macro_rules! assert_none {
-        ($what:ident, $($str:tt),+) => {{
-            $(
-                for b in $str.chars() {
-                    if b.$what() {
-                        panic!("expected not-{}({}) but it is",
-                               stringify!($what), b);
-                    }
-                }
-                for b in $str.as_bytes().iter() {
-                    if b.$what() {
-                        panic!("expected not-{}(0x{:02x})) but it is",
-                               stringify!($what), b);
-                    }
-                }
-            )*
-        }};
-        ($what:ident, $($str:tt),+,) => (assert_none!($what,$($str),+))
-    }
-
-    #[test]
-    fn test_is_ascii_alphabetic() {
-        assert_all!(is_ascii_alphabetic,
-            "",
-            "abcdefghijklmnopqrstuvwxyz",
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-        );
-        assert_none!(is_ascii_alphabetic,
-            "0123456789",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-            " \t\n\x0c\r",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_uppercase() {
-        assert_all!(is_ascii_uppercase,
-            "",
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-        );
-        assert_none!(is_ascii_uppercase,
-            "abcdefghijklmnopqrstuvwxyz",
-            "0123456789",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-            " \t\n\x0c\r",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_lowercase() {
-        assert_all!(is_ascii_lowercase,
-            "abcdefghijklmnopqrstuvwxyz",
-        );
-        assert_none!(is_ascii_lowercase,
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-            "0123456789",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-            " \t\n\x0c\r",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_alphanumeric() {
-        assert_all!(is_ascii_alphanumeric,
-            "",
-            "abcdefghijklmnopqrstuvwxyz",
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-            "0123456789",
-        );
-        assert_none!(is_ascii_alphanumeric,
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-            " \t\n\x0c\r",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_digit() {
-        assert_all!(is_ascii_digit,
-            "",
-            "0123456789",
-        );
-        assert_none!(is_ascii_digit,
-            "abcdefghijklmnopqrstuvwxyz",
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-            " \t\n\x0c\r",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_hexdigit() {
-        assert_all!(is_ascii_hexdigit,
-            "",
-            "0123456789",
-            "abcdefABCDEF",
-        );
-        assert_none!(is_ascii_hexdigit,
-            "ghijklmnopqrstuvwxyz",
-            "GHIJKLMNOQPRSTUVWXYZ",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-            " \t\n\x0c\r",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_punctuation() {
-        assert_all!(is_ascii_punctuation,
-            "",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-        );
-        assert_none!(is_ascii_punctuation,
-            "abcdefghijklmnopqrstuvwxyz",
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-            "0123456789",
-            " \t\n\x0c\r",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_graphic() {
-        assert_all!(is_ascii_graphic,
-            "",
-            "abcdefghijklmnopqrstuvwxyz",
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-            "0123456789",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-        );
-        assert_none!(is_ascii_graphic,
-            " \t\n\x0c\r",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_whitespace() {
-        assert_all!(is_ascii_whitespace,
-            "",
-            " \t\n\x0c\r",
-        );
-        assert_none!(is_ascii_whitespace,
-            "abcdefghijklmnopqrstuvwxyz",
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-            "0123456789",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x0b\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-    }
-
-    #[test]
-    fn test_is_ascii_control() {
-        assert_all!(is_ascii_control,
-            "",
-            "\x00\x01\x02\x03\x04\x05\x06\x07",
-            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
-            "\x10\x11\x12\x13\x14\x15\x16\x17",
-            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
-            "\x7f",
-        );
-        assert_none!(is_ascii_control,
-            "abcdefghijklmnopqrstuvwxyz",
-            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
-            "0123456789",
-            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
-            " ",
-        );
-    }
-}
diff --git a/ctr-std/src/collections/hash/map.rs b/ctr-std/src/collections/hash/map.rs
index a82ff91..20a4f9b 100644
--- a/ctr-std/src/collections/hash/map.rs
+++ b/ctr-std/src/collections/hash/map.rs
@@ -11,6 +11,7 @@
 use self::Entry::*;
 use self::VacantEntryState::*;
 
+use alloc::{Global, Alloc, CollectionAllocErr};
 use cell::Cell;
 use borrow::Borrow;
 use cmp::max;
@@ -19,8 +20,7 @@ use fmt::{self, Debug};
 use hash::{Hash, Hasher, BuildHasher, SipHasher13};
 use iter::{FromIterator, FusedIterator};
 use mem::{self, replace};
-use ops::{Deref, Index, InPlace, Place, Placer};
-use ptr;
+use ops::{Deref, Index};
 use sys;
 
 use super::table::{self, Bucket, EmptyBucket, FullBucket, FullBucketMut, RawTable, SafeHash};
@@ -42,21 +42,28 @@ impl DefaultResizePolicy {
     /// provide that capacity, accounting for maximum loading. The raw capacity
     /// is always zero or a power of two.
     #[inline]
-    fn raw_capacity(&self, len: usize) -> usize {
+    fn try_raw_capacity(&self, len: usize) -> Result<usize, CollectionAllocErr> {
         if len == 0 {
-            0
+            Ok(0)
         } else {
             // 1. Account for loading: `raw_capacity >= len * 1.1`.
             // 2. Ensure it is a power of two.
             // 3. Ensure it is at least the minimum size.
-            let mut raw_cap = len * 11 / 10;
-            assert!(raw_cap >= len, "raw_cap overflow");
-            raw_cap = raw_cap.checked_next_power_of_two().expect("raw_capacity overflow");
+            let mut raw_cap = len.checked_mul(11)
+                .map(|l| l / 10)
+                .and_then(|l| l.checked_next_power_of_two())
+                .ok_or(CollectionAllocErr::CapacityOverflow)?;
+
             raw_cap = max(MIN_NONZERO_RAW_CAPACITY, raw_cap);
-            raw_cap
+            Ok(raw_cap)
         }
     }
 
+    #[inline]
+    fn raw_capacity(&self, len: usize) -> usize {
+        self.try_raw_capacity(len).expect("raw_capacity overflow")
+    }
+
     /// The capacity of the given raw capacity.
     #[inline]
     fn capacity(&self, raw_cap: usize) -> usize {
@@ -620,7 +627,7 @@ impl<K: Hash + Eq, V> HashMap<K, V, RandomState> {
     ///
     /// ```
     /// use std::collections::HashMap;
-    /// let mut map: HashMap<&str, isize> = HashMap::new();
+    /// let mut map: HashMap<&str, i32> = HashMap::new();
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -637,7 +644,7 @@ impl<K: Hash + Eq, V> HashMap<K, V, RandomState> {
     ///
     /// ```
     /// use std::collections::HashMap;
-    /// let mut map: HashMap<&str, isize> = HashMap::with_capacity(10);
+    /// let mut map: HashMap<&str, i32> = HashMap::with_capacity(10);
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -724,7 +731,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// use std::collections::hash_map::RandomState;
     ///
     /// let hasher = RandomState::new();
-    /// let map: HashMap<isize, isize> = HashMap::with_hasher(hasher);
+    /// let map: HashMap<i32, i32> = HashMap::with_hasher(hasher);
     /// let hasher: &RandomState = map.hasher();
     /// ```
     #[stable(feature = "hashmap_public_hasher", since = "1.9.0")]
@@ -741,7 +748,7 @@ impl<K, V, S> HashMap<K, V, S>
     ///
     /// ```
     /// use std::collections::HashMap;
-    /// let map: HashMap<isize, isize> = HashMap::with_capacity(100);
+    /// let map: HashMap<i32, i32> = HashMap::with_capacity(100);
     /// assert!(map.capacity() >= 100);
     /// ```
     #[inline]
@@ -770,22 +777,50 @@ impl<K, V, S> HashMap<K, V, S>
     ///
     /// ```
     /// use std::collections::HashMap;
-    /// let mut map: HashMap<&str, isize> = HashMap::new();
+    /// let mut map: HashMap<&str, i32> = HashMap::new();
     /// map.reserve(10);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn reserve(&mut self, additional: usize) {
+        match self.try_reserve(additional) {
+            Err(CollectionAllocErr::CapacityOverflow) => panic!("capacity overflow"),
+            Err(CollectionAllocErr::AllocErr) => Global.oom(),
+            Ok(()) => { /* yay */ }
+         }
+    }
+
+    /// Tries to reserve capacity for at least `additional` more elements to be inserted
+    /// in the given `HashMap<K,V>`. The collection may reserve more space to avoid
+    /// frequent reallocations.
+    ///
+    /// # Errors
+    ///
+    /// If the capacity overflows, or the allocator reports a failure, then an error
+    /// is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(try_reserve)]
+    /// use std::collections::HashMap;
+    /// let mut map: HashMap<&str, isize> = HashMap::new();
+    /// map.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");
+    /// ```
+    #[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
+    pub fn try_reserve(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
         let remaining = self.capacity() - self.len(); // this can't overflow
         if remaining < additional {
-            let min_cap = self.len().checked_add(additional).expect("reserve overflow");
-            let raw_cap = self.resize_policy.raw_capacity(min_cap);
-            self.resize(raw_cap);
+            let min_cap = self.len().checked_add(additional)
+                .ok_or(CollectionAllocErr::CapacityOverflow)?;
+            let raw_cap = self.resize_policy.try_raw_capacity(min_cap)?;
+            self.try_resize(raw_cap)?;
         } else if self.table.tag() && remaining <= self.len() {
             // Probe sequence is too long and table is half full,
             // resize early to reduce probing length.
             let new_capacity = self.table.capacity() * 2;
-            self.resize(new_capacity);
+            self.try_resize(new_capacity)?;
         }
+        Ok(())
     }
 
     /// Resizes the internal vectors to a new capacity. It's your
@@ -795,15 +830,15 @@ impl<K, V, S> HashMap<K, V, S>
     ///   2) Ensure `new_raw_cap` is a power of two or zero.
     #[inline(never)]
     #[cold]
-    fn resize(&mut self, new_raw_cap: usize) {
+    fn try_resize(&mut self, new_raw_cap: usize) -> Result<(), CollectionAllocErr> {
         assert!(self.table.size() <= new_raw_cap);
         assert!(new_raw_cap.is_power_of_two() || new_raw_cap == 0);
 
-        let mut old_table = replace(&mut self.table, RawTable::new(new_raw_cap));
+        let mut old_table = replace(&mut self.table, RawTable::try_new(new_raw_cap)?);
         let old_size = old_table.size();
 
         if old_table.size() == 0 {
-            return;
+            return Ok(());
         }
 
         let mut bucket = Bucket::head_bucket(&mut old_table);
@@ -838,6 +873,7 @@ impl<K, V, S> HashMap<K, V, S>
         }
 
         assert_eq!(self.table.size(), old_size);
+        Ok(())
     }
 
     /// Shrinks the capacity of the map as much as possible. It will drop
@@ -849,7 +885,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// ```
     /// use std::collections::HashMap;
     ///
-    /// let mut map: HashMap<isize, isize> = HashMap::with_capacity(100);
+    /// let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
     /// map.insert(1, 2);
     /// map.insert(3, 4);
     /// assert!(map.capacity() >= 100);
@@ -872,6 +908,46 @@ impl<K, V, S> HashMap<K, V, S>
         }
     }
 
+    /// Shrinks the capacity of the map with a lower limit. It will drop
+    /// down no lower than the supplied limit while maintaining the internal rules
+    /// and possibly leaving some space in accordance with the resize policy.
+    ///
+    /// Panics if the current capacity is smaller than the supplied
+    /// minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(shrink_to)]
+    /// use std::collections::HashMap;
+    ///
+    /// let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
+    /// map.insert(1, 2);
+    /// map.insert(3, 4);
+    /// assert!(map.capacity() >= 100);
+    /// map.shrink_to(10);
+    /// assert!(map.capacity() >= 10);
+    /// map.shrink_to(0);
+    /// assert!(map.capacity() >= 2);
+    /// ```
+    #[unstable(feature = "shrink_to", reason = "new API", issue="0")]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        assert!(self.capacity() >= min_capacity, "Tried to shrink to a larger capacity");
+
+        let new_raw_cap = self.resize_policy.raw_capacity(max(self.len(), min_capacity));
+        if self.raw_capacity() != new_raw_cap {
+            let old_table = replace(&mut self.table, RawTable::new(new_raw_cap));
+            let old_size = old_table.size();
+
+            // Shrink the table. Naive algorithm for resizing:
+            for (h, k, v) in old_table.into_iter() {
+                self.insert_hashed_nocheck(h, k, v);
+            }
+
+            debug_assert_eq!(self.table.size(), old_size);
+        }
+    }
+
     /// Insert a pre-hashed key-value pair, without first checking
     /// that there's enough room in the buckets. Returns a reference to the
     /// newly insert value.
@@ -1146,6 +1222,34 @@ impl<K, V, S> HashMap<K, V, S>
         self.search(k).map(|bucket| bucket.into_refs().1)
     }
 
+    /// Returns the key-value pair corresponding to the supplied key.
+    ///
+    /// The supplied key may be any borrowed form of the map's key type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the key type.
+    ///
+    /// [`Eq`]: ../../std/cmp/trait.Eq.html
+    /// [`Hash`]: ../../std/hash/trait.Hash.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(map_get_key_value)]
+    /// use std::collections::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, "a");
+    /// assert_eq!(map.get_key_value(&1), Some((&1, &"a")));
+    /// assert_eq!(map.get_key_value(&2), None);
+    /// ```
+    #[unstable(feature = "map_get_key_value", issue = "49347")]
+    pub fn get_key_value<Q: ?Sized>(&self, k: &Q) -> Option<(&K, &V)>
+        where K: Borrow<Q>,
+              Q: Hash + Eq
+    {
+        self.search(k).map(|bucket| bucket.into_refs())
+    }
+
     /// Returns true if the map contains a value for the specified key.
     ///
     /// The key may be any borrowed form of the map's key type, but
@@ -1306,7 +1410,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// ```
     /// use std::collections::HashMap;
     ///
-    /// let mut map: HashMap<isize, isize> = (0..8).map(|x|(x, x*10)).collect();
+    /// let mut map: HashMap<i32, i32> = (0..8).map(|x|(x, x*10)).collect();
     /// map.retain(|&k, _| k % 2 == 0);
     /// assert_eq!(map.len(), 4);
     /// ```
@@ -1722,7 +1826,7 @@ impl<K, V, S> IntoIterator for HashMap<K, V, S>
     /// map.insert("c", 3);
     ///
     /// // Not possible with .iter()
-    /// let vec: Vec<(&str, isize)> = map.into_iter().collect();
+    /// let vec: Vec<(&str, i32)> = map.into_iter().collect();
     /// ```
     fn into_iter(self) -> IntoIter<K, V> {
         IntoIter { inner: self.table.into_iter() }
@@ -1750,7 +1854,7 @@ impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for Iter<'a, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1773,7 +1877,7 @@ impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for IterMut<'a, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1808,7 +1912,7 @@ impl<K, V> ExactSizeIterator for IntoIter<K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<K, V> FusedIterator for IntoIter<K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1840,7 +1944,7 @@ impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for Keys<'a, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1863,7 +1967,7 @@ impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for Values<'a, K, V> {}
 
 #[stable(feature = "map_values_mut", since = "1.10.0")]
@@ -1886,7 +1990,7 @@ impl<'a, K, V> ExactSizeIterator for ValuesMut<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for ValuesMut<'a, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1921,7 +2025,7 @@ impl<'a, K, V> ExactSizeIterator for Drain<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for Drain<'a, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1936,80 +2040,6 @@ impl<'a, K, V> fmt::Debug for Drain<'a, K, V>
     }
 }
 
-/// A place for insertion to a `Entry`.
-///
-/// See [`HashMap::entry`](struct.HashMap.html#method.entry) for details.
-#[must_use = "places do nothing unless written to with `<-` syntax"]
-#[unstable(feature = "collection_placement",
-           reason = "struct name and placement protocol is subject to change",
-           issue = "30172")]
-pub struct EntryPlace<'a, K: 'a, V: 'a> {
-    bucket: FullBucketMut<'a, K, V>,
-}
-
-#[unstable(feature = "collection_placement",
-           reason = "struct name and placement protocol is subject to change",
-           issue = "30172")]
-impl<'a, K: 'a + Debug, V: 'a + Debug> Debug for EntryPlace<'a, K, V> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("EntryPlace")
-            .field("key", self.bucket.read().0)
-            .field("value", self.bucket.read().1)
-            .finish()
-    }
-}
-
-#[unstable(feature = "collection_placement",
-           reason = "struct name and placement protocol is subject to change",
-           issue = "30172")]
-impl<'a, K, V> Drop for EntryPlace<'a, K, V> {
-    fn drop(&mut self) {
-        // Inplacement insertion failed. Only key need to drop.
-        // The value is failed to insert into map.
-        unsafe { self.bucket.remove_key() };
-    }
-}
-
-#[unstable(feature = "collection_placement",
-           reason = "placement protocol is subject to change",
-           issue = "30172")]
-impl<'a, K, V> Placer<V> for Entry<'a, K, V> {
-    type Place = EntryPlace<'a, K, V>;
-
-    fn make_place(self) -> EntryPlace<'a, K, V> {
-        let b = match self {
-            Occupied(mut o) => {
-                unsafe { ptr::drop_in_place(o.elem.read_mut().1); }
-                o.elem
-            }
-            Vacant(v) => {
-                unsafe { v.insert_key() }
-            }
-        };
-        EntryPlace { bucket: b }
-    }
-}
-
-#[unstable(feature = "collection_placement",
-           reason = "placement protocol is subject to change",
-           issue = "30172")]
-unsafe impl<'a, K, V> Place<V> for EntryPlace<'a, K, V> {
-    fn pointer(&mut self) -> *mut V {
-        self.bucket.read_mut().1
-    }
-}
-
-#[unstable(feature = "collection_placement",
-           reason = "placement protocol is subject to change",
-           issue = "30172")]
-impl<'a, K, V> InPlace<V> for EntryPlace<'a, K, V> {
-    type Owner = ();
-
-    unsafe fn finalize(self) {
-        mem::forget(self);
-    }
-}
-
 impl<'a, K, V> Entry<'a, K, V> {
     #[stable(feature = "rust1", since = "1.0.0")]
     /// Ensures a value is in the entry by inserting the default if empty, and returns
@@ -2082,7 +2112,6 @@ impl<'a, K, V> Entry<'a, K, V> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(entry_and_modify)]
     /// use std::collections::HashMap;
     ///
     /// let mut map: HashMap<&str, u32> = HashMap::new();
@@ -2097,7 +2126,7 @@ impl<'a, K, V> Entry<'a, K, V> {
     ///    .or_insert(42);
     /// assert_eq!(map["poneyland"], 43);
     /// ```
-    #[unstable(feature = "entry_and_modify", issue = "44733")]
+    #[stable(feature = "entry_and_modify", since = "1.26.0")]
     pub fn and_modify<F>(self, mut f: F) -> Self
         where F: FnMut(&mut V)
     {
@@ -2433,26 +2462,6 @@ impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V> {
         };
         b.into_mut_refs().1
     }
-
-    // Only used for InPlacement insert. Avoid unnecessary value copy.
-    // The value remains uninitialized.
-    unsafe fn insert_key(self) -> FullBucketMut<'a, K, V> {
-        match self.elem {
-            NeqElem(mut bucket, disp) => {
-                if disp >= DISPLACEMENT_THRESHOLD {
-                    bucket.table_mut().set_tag(true);
-                }
-                let uninit = mem::uninitialized();
-                robin_hood(bucket, disp, self.hash, self.key, uninit)
-            },
-            NoElem(mut bucket, disp) => {
-                if disp >= DISPLACEMENT_THRESHOLD {
-                    bucket.table_mut().set_tag(true);
-                }
-                bucket.put_key(self.hash, self.key)
-            },
-        }
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -2717,7 +2726,9 @@ mod test_map {
     use super::RandomState;
     use cell::RefCell;
     use rand::{thread_rng, Rng};
-    use panic;
+    use realstd::collections::CollectionAllocErr::*;
+    use realstd::mem::size_of;
+    use realstd::usize;
 
     #[test]
     fn test_zero_capacities() {
@@ -2787,24 +2798,24 @@ mod test_map {
         assert_eq!(m2.len(), 2);
     }
 
-    thread_local! { static DROP_VECTOR: RefCell<Vec<isize>> = RefCell::new(Vec::new()) }
+    thread_local! { static DROP_VECTOR: RefCell<Vec<i32>> = RefCell::new(Vec::new()) }
 
     #[derive(Hash, PartialEq, Eq)]
-    struct Dropable {
+    struct Droppable {
         k: usize,
     }
 
-    impl Dropable {
-        fn new(k: usize) -> Dropable {
+    impl Droppable {
+        fn new(k: usize) -> Droppable {
             DROP_VECTOR.with(|slot| {
                 slot.borrow_mut()[k] += 1;
             });
 
-            Dropable { k: k }
+            Droppable { k: k }
         }
     }
 
-    impl Drop for Dropable {
+    impl Drop for Droppable {
         fn drop(&mut self) {
             DROP_VECTOR.with(|slot| {
                 slot.borrow_mut()[self.k] -= 1;
@@ -2812,9 +2823,9 @@ mod test_map {
         }
     }
 
-    impl Clone for Dropable {
-        fn clone(&self) -> Dropable {
-            Dropable::new(self.k)
+    impl Clone for Droppable {
+        fn clone(&self) -> Droppable {
+            Droppable::new(self.k)
         }
     }
 
@@ -2834,8 +2845,8 @@ mod test_map {
             });
 
             for i in 0..100 {
-                let d1 = Dropable::new(i);
-                let d2 = Dropable::new(i + 100);
+                let d1 = Droppable::new(i);
+                let d2 = Droppable::new(i + 100);
                 m.insert(d1, d2);
             }
 
@@ -2846,7 +2857,7 @@ mod test_map {
             });
 
             for i in 0..50 {
-                let k = Dropable::new(i);
+                let k = Droppable::new(i);
                 let v = m.remove(&k);
 
                 assert!(v.is_some());
@@ -2893,8 +2904,8 @@ mod test_map {
             });
 
             for i in 0..100 {
-                let d1 = Dropable::new(i);
-                let d2 = Dropable::new(i + 100);
+                let d1 = Droppable::new(i);
+                let d2 = Droppable::new(i + 100);
                 hm.insert(d1, d2);
             }
 
@@ -2944,13 +2955,13 @@ mod test_map {
 
     #[test]
     fn test_empty_remove() {
-        let mut m: HashMap<isize, bool> = HashMap::new();
+        let mut m: HashMap<i32, bool> = HashMap::new();
         assert_eq!(m.remove(&0), None);
     }
 
     #[test]
     fn test_empty_entry() {
-        let mut m: HashMap<isize, bool> = HashMap::new();
+        let mut m: HashMap<i32, bool> = HashMap::new();
         match m.entry(0) {
             Occupied(_) => panic!(),
             Vacant(_) => {}
@@ -2961,7 +2972,7 @@ mod test_map {
 
     #[test]
     fn test_empty_iter() {
-        let mut m: HashMap<isize, bool> = HashMap::new();
+        let mut m: HashMap<i32, bool> = HashMap::new();
         assert_eq!(m.drain().next(), None);
         assert_eq!(m.keys().next(), None);
         assert_eq!(m.values().next(), None);
@@ -3462,7 +3473,7 @@ mod test_map {
     fn test_entry_take_doesnt_corrupt() {
         #![allow(deprecated)] //rand
         // Test for #19292
-        fn check(m: &HashMap<isize, ()>) {
+        fn check(m: &HashMap<i32, ()>) {
             for k in m.keys() {
                 assert!(m.contains_key(k),
                         "{} is in keys() but not in the map?", k);
@@ -3571,7 +3582,7 @@ mod test_map {
 
     #[test]
     fn test_retain() {
-        let mut map: HashMap<isize, isize> = (0..100).map(|x|(x, x*10)).collect();
+        let mut map: HashMap<i32, i32> = (0..100).map(|x|(x, x*10)).collect();
 
         map.retain(|&k, _| k % 2 == 0);
         assert_eq!(map.len(), 50);
@@ -3601,55 +3612,31 @@ mod test_map {
     }
 
     #[test]
-    fn test_placement_in() {
-        let mut map = HashMap::new();
-        map.extend((0..10).map(|i| (i, i)));
-
-        map.entry(100) <- 100;
-        assert_eq!(map[&100], 100);
+    fn test_try_reserve() {
 
-        map.entry(0) <- 10;
-        assert_eq!(map[&0], 10);
-
-        assert_eq!(map.len(), 11);
-    }
-
-    #[test]
-    fn test_placement_panic() {
-        let mut map = HashMap::new();
-        map.extend((0..10).map(|i| (i, i)));
+        let mut empty_bytes: HashMap<u8,u8> = HashMap::new();
 
-        fn mkpanic() -> usize { panic!() }
+        const MAX_USIZE: usize = usize::MAX;
 
-        // modify existing key
-        // when panic happens, previous key is removed.
-        let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| { map.entry(0) <- mkpanic(); }));
-        assert_eq!(map.len(), 9);
-        assert!(!map.contains_key(&0));
+        // HashMap and RawTables use complicated size calculations
+        // hashes_size is sizeof(HashUint) * capacity;
+        // pairs_size is sizeof((K. V)) * capacity;
+        // alignment_hashes_size is 8
+        // alignment_pairs size is 4
+        let size_of_multiplier = (size_of::<usize>() + size_of::<(u8, u8)>()).next_power_of_two();
+        // The following formula is used to calculate the new capacity
+        let max_no_ovf = ((MAX_USIZE / 11) * 10) / size_of_multiplier - 1;
 
-        // add new key
-        let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| { map.entry(100) <- mkpanic(); }));
-        assert_eq!(map.len(), 9);
-        assert!(!map.contains_key(&100));
-    }
+        if let Err(CapacityOverflow) = empty_bytes.try_reserve(MAX_USIZE) {
+        } else { panic!("usize::MAX should trigger an overflow!"); }
 
-    #[test]
-    fn test_placement_drop() {
-        // correctly drop
-        struct TestV<'a>(&'a mut bool);
-        impl<'a> Drop for TestV<'a> {
-            fn drop(&mut self) {
-                if !*self.0 { panic!("value double drop!"); } // no double drop
-                *self.0 = false;
-            }
+        if size_of::<usize>() < 8 {
+            if let Err(CapacityOverflow) = empty_bytes.try_reserve(max_no_ovf) {
+            } else { panic!("isize::MAX + 1 should trigger a CapacityOverflow!") }
+        } else {
+            if let Err(AllocErr) = empty_bytes.try_reserve(max_no_ovf) {
+            } else { panic!("isize::MAX + 1 should trigger an OOM!") }
         }
-
-        fn makepanic<'a>() -> TestV<'a> { panic!() }
-
-        let mut can_drop = true;
-        let mut hm = HashMap::new();
-        hm.insert(0, TestV(&mut can_drop));
-        let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| { hm.entry(0) <- makepanic(); }));
-        assert_eq!(hm.len(), 0);
     }
+
 }
diff --git a/ctr-std/src/collections/hash/set.rs b/ctr-std/src/collections/hash/set.rs
index e9427fb..855563a 100644
--- a/ctr-std/src/collections/hash/set.rs
+++ b/ctr-std/src/collections/hash/set.rs
@@ -292,6 +292,34 @@ impl<T, S> HashSet<T, S>
         self.map.shrink_to_fit()
     }
 
+    /// Shrinks the capacity of the set with a lower limit. It will drop
+    /// down no lower than the supplied limit while maintaining the internal rules
+    /// and possibly leaving some space in accordance with the resize policy.
+    ///
+    /// Panics if the current capacity is smaller than the supplied
+    /// minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(shrink_to)]
+    /// use std::collections::HashSet;
+    ///
+    /// let mut set = HashSet::with_capacity(100);
+    /// set.insert(1);
+    /// set.insert(2);
+    /// assert!(set.capacity() >= 100);
+    /// set.shrink_to(10);
+    /// assert!(set.capacity() >= 10);
+    /// set.shrink_to(0);
+    /// assert!(set.capacity() >= 2);
+    /// ```
+    #[inline]
+    #[unstable(feature = "shrink_to", reason = "new API", issue="0")]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.map.shrink_to(min_capacity)
+    }
+
     /// An iterator visiting all elements in arbitrary order.
     /// The iterator element type is `&'a T`.
     ///
@@ -724,7 +752,7 @@ impl<T, S> HashSet<T, S>
     /// use std::collections::HashSet;
     ///
     /// let xs = [1,2,3,4,5,6];
-    /// let mut set: HashSet<isize> = xs.iter().cloned().collect();
+    /// let mut set: HashSet<i32> = xs.iter().cloned().collect();
     /// set.retain(|&k| k % 2 == 0);
     /// assert_eq!(set.len(), 3);
     /// ```
@@ -1097,7 +1125,7 @@ impl<'a, K> ExactSizeIterator for Iter<'a, K> {
         self.iter.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K> FusedIterator for Iter<'a, K> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1124,7 +1152,7 @@ impl<K> ExactSizeIterator for IntoIter<K> {
         self.iter.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<K> FusedIterator for IntoIter<K> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1155,7 +1183,7 @@ impl<'a, K> ExactSizeIterator for Drain<'a, K> {
         self.iter.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K> FusedIterator for Drain<'a, K> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1208,7 +1236,7 @@ impl<'a, T, S> fmt::Debug for Intersection<'a, T, S>
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, T, S> FusedIterator for Intersection<'a, T, S>
     where T: Eq + Hash,
           S: BuildHasher
@@ -1244,7 +1272,7 @@ impl<'a, T, S> Iterator for Difference<'a, T, S>
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, T, S> FusedIterator for Difference<'a, T, S>
     where T: Eq + Hash,
           S: BuildHasher
@@ -1283,7 +1311,7 @@ impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S>
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, T, S> FusedIterator for SymmetricDifference<'a, T, S>
     where T: Eq + Hash,
           S: BuildHasher
@@ -1307,7 +1335,7 @@ impl<'a, T, S> Clone for Union<'a, T, S> {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, T, S> FusedIterator for Union<'a, T, S>
     where T: Eq + Hash,
           S: BuildHasher
@@ -1745,7 +1773,7 @@ mod test_set {
     #[test]
     fn test_retain() {
         let xs = [1, 2, 3, 4, 5, 6];
-        let mut set: HashSet<isize> = xs.iter().cloned().collect();
+        let mut set: HashSet<i32> = xs.iter().cloned().collect();
         set.retain(|&k| k % 2 == 0);
         assert_eq!(set.len(), 3);
         assert!(set.contains(&2));
diff --git a/ctr-std/src/collections/hash/table.rs b/ctr-std/src/collections/hash/table.rs
index 73bd574..93f0590 100644
--- a/ctr-std/src/collections/hash/table.rs
+++ b/ctr-std/src/collections/hash/table.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use alloc::heap::{Heap, Alloc, Layout};
-
+use alloc::{Global, Alloc, Layout, CollectionAllocErr};
 use cmp;
 use hash::{BuildHasher, Hash, Hasher};
 use marker;
@@ -484,21 +483,6 @@ impl<K, V, M> EmptyBucket<K, V, M>
             table: self.table,
         }
     }
-
-    /// Puts given key, remain value uninitialized.
-    /// It is only used for inplacement insertion.
-    pub unsafe fn put_key(mut self, hash: SafeHash, key: K) -> FullBucket<K, V, M> {
-        *self.raw.hash() = hash.inspect();
-        let pair_ptr = self.raw.pair();
-        ptr::write(&mut (*pair_ptr).0, key);
-
-        self.table.borrow_table_mut().size += 1;
-
-        FullBucket {
-            raw: self.raw,
-            table: self.table,
-        }
-    }
 }
 
 impl<K, V, M: Deref<Target = RawTable<K, V>>> FullBucket<K, V, M> {
@@ -574,17 +558,6 @@ impl<'t, K, V> FullBucket<K, V, &'t mut RawTable<K, V>> {
             v)
         }
     }
-
-    /// Remove this bucket's `key` from the hashtable.
-    /// Only used for inplacement insertion.
-    /// NOTE: `Value` is uninitialized when this function is called, don't try to drop the `Value`.
-    pub unsafe fn remove_key(&mut self) {
-        self.table.size -= 1;
-
-        *self.raw.hash() = EMPTY_BUCKET;
-        let pair_ptr = self.raw.pair();
-        ptr::drop_in_place(&mut (*pair_ptr).0); // only drop key
-    }
 }
 
 // This use of `Put` is misleading and restrictive, but safe and sufficient for our use cases
@@ -741,14 +714,15 @@ fn test_offset_calculation() {
 impl<K, V> RawTable<K, V> {
     /// Does not initialize the buckets. The caller should ensure they,
     /// at the very least, set every hash to EMPTY_BUCKET.
-    unsafe fn new_uninitialized(capacity: usize) -> RawTable<K, V> {
+    /// Returns an error if it cannot allocate or capacity overflows.
+    unsafe fn try_new_uninitialized(capacity: usize) -> Result<RawTable<K, V>, CollectionAllocErr> {
         if capacity == 0 {
-            return RawTable {
+            return Ok(RawTable {
                 size: 0,
                 capacity_mask: capacity.wrapping_sub(1),
                 hashes: TaggedHashUintPtr::new(EMPTY as *mut HashUint),
                 marker: marker::PhantomData,
-            };
+            });
         }
 
         // No need for `checked_mul` before a more restrictive check performed
@@ -768,25 +742,36 @@ impl<K, V> RawTable<K, V> {
                                                            align_of::<HashUint>(),
                                                            pairs_size,
                                                            align_of::<(K, V)>());
-        assert!(!oflo, "capacity overflow");
+        if oflo {
+            return Err(CollectionAllocErr::CapacityOverflow);
+        }
 
         // One check for overflow that covers calculation and rounding of size.
-        let size_of_bucket = size_of::<HashUint>().checked_add(size_of::<(K, V)>()).unwrap();
-        assert!(size >=
-                capacity.checked_mul(size_of_bucket)
-                    .expect("capacity overflow"),
-                "capacity overflow");
-
-        let buffer = Heap.alloc(Layout::from_size_align(size, alignment).unwrap())
-            .unwrap_or_else(|e| Heap.oom(e));
+        let size_of_bucket = size_of::<HashUint>().checked_add(size_of::<(K, V)>())
+            .ok_or(CollectionAllocErr::CapacityOverflow)?;
+        let capacity_mul_size_of_bucket = capacity.checked_mul(size_of_bucket);
+        if capacity_mul_size_of_bucket.is_none() || size < capacity_mul_size_of_bucket.unwrap() {
+            return Err(CollectionAllocErr::CapacityOverflow);
+        }
 
-        let hashes = buffer as *mut HashUint;
+        let buffer = Global.alloc(Layout::from_size_align(size, alignment)
+            .map_err(|_| CollectionAllocErr::CapacityOverflow)?)?;
 
-        RawTable {
+        Ok(RawTable {
             capacity_mask: capacity.wrapping_sub(1),
             size: 0,
-            hashes: TaggedHashUintPtr::new(hashes),
+            hashes: TaggedHashUintPtr::new(buffer.cast().as_ptr()),
             marker: marker::PhantomData,
+        })
+    }
+
+    /// Does not initialize the buckets. The caller should ensure they,
+    /// at the very least, set every hash to EMPTY_BUCKET.
+    unsafe fn new_uninitialized(capacity: usize) -> RawTable<K, V> {
+        match Self::try_new_uninitialized(capacity) {
+            Err(CollectionAllocErr::CapacityOverflow) => panic!("capacity overflow"),
+            Err(CollectionAllocErr::AllocErr) => Global.oom(),
+            Ok(table) => { table }
         }
     }
 
@@ -809,13 +794,23 @@ impl<K, V> RawTable<K, V> {
         }
     }
 
+    /// Tries to create a new raw table from a given capacity. If it cannot allocate,
+    /// it returns with AllocErr.
+    pub fn try_new(capacity: usize) -> Result<RawTable<K, V>, CollectionAllocErr> {
+        unsafe {
+            let ret = RawTable::try_new_uninitialized(capacity)?;
+            ptr::write_bytes(ret.hashes.ptr(), 0, capacity);
+            Ok(ret)
+        }
+    }
+
     /// Creates a new raw table from a given capacity. All buckets are
     /// initially empty.
     pub fn new(capacity: usize) -> RawTable<K, V> {
-        unsafe {
-            let ret = RawTable::new_uninitialized(capacity);
-            ptr::write_bytes(ret.hashes.ptr(), 0, capacity);
-            ret
+        match Self::try_new(capacity) {
+            Err(CollectionAllocErr::CapacityOverflow) => panic!("capacity overflow"),
+            Err(CollectionAllocErr::AllocErr) => Global.oom(),
+            Ok(table) => { table }
         }
     }
 
@@ -1188,8 +1183,8 @@ unsafe impl<#[may_dangle] K, #[may_dangle] V> Drop for RawTable<K, V> {
         debug_assert!(!oflo, "should be impossible");
 
         unsafe {
-            Heap.dealloc(self.hashes.ptr() as *mut u8,
-                         Layout::from_size_align(size, align).unwrap());
+            Global.dealloc(NonNull::new_unchecked(self.hashes.ptr()).as_opaque(),
+                           Layout::from_size_align(size, align).unwrap());
             // Remember how everything was allocated out of one buffer
             // during initialization? We only need one call to free here.
         }
diff --git a/ctr-std/src/collections/mod.rs b/ctr-std/src/collections/mod.rs
index b8a6a66..9cf7382 100644
--- a/ctr-std/src/collections/mod.rs
+++ b/ctr-std/src/collections/mod.rs
@@ -64,11 +64,11 @@
 //! * You want a map, with no extra functionality.
 //!
 //! ### Use a `BTreeMap` when:
+//! * You want a map sorted by its keys.
+//! * You want to be able to get a range of entries on-demand.
 //! * You're interested in what the smallest or largest key-value pair is.
 //! * You want to find the largest or smallest key that is smaller or larger
 //!   than something.
-//! * You want to be able to get all of the entries in order on-demand.
-//! * You want a map sorted by its keys.
 //!
 //! ### Use the `Set` variant of any of these `Map`s when:
 //! * You just want to remember which keys you've seen.
@@ -420,23 +420,33 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::Bound;
+#[rustc_deprecated(reason = "moved to `std::ops::Bound`", since = "1.26.0")]
+#[doc(hidden)]
+pub use ops::Bound;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::{BinaryHeap, BTreeMap, BTreeSet};
+pub use alloc_crate::{BinaryHeap, BTreeMap, BTreeSet};
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::{LinkedList, VecDeque};
+pub use alloc_crate::{LinkedList, VecDeque};
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::{binary_heap, btree_map, btree_set};
+pub use alloc_crate::{binary_heap, btree_map, btree_set};
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::{linked_list, vec_deque};
+pub use alloc_crate::{linked_list, vec_deque};
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::hash_map::HashMap;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::hash_set::HashSet;
 
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::range;
+#[unstable(feature = "collections_range", issue = "30877")]
+#[rustc_deprecated(reason = "renamed and moved to `std::ops::RangeBounds`", since = "1.26.0")]
+#[doc(hidden)]
+/// Range syntax
+pub mod range {
+    pub use ops::RangeBounds as RangeArgument;
+}
+
+#[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
+pub use heap::CollectionAllocErr;
 
 mod hash;
 
diff --git a/ctr-std/src/env.rs b/ctr-std/src/env.rs
index c4946b6..a103c0b 100644
--- a/ctr-std/src/env.rs
+++ b/ctr-std/src/env.rs
@@ -552,17 +552,17 @@ pub fn home_dir() -> Option<PathBuf> {
 ///
 /// [msdn]: https://msdn.microsoft.com/en-us/library/windows/desktop/aa364992(v=vs.85).aspx
 ///
-/// ```
+/// ```no_run
 /// use std::env;
 /// use std::fs::File;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let mut dir = env::temp_dir();
-/// dir.push("foo.txt");
+/// fn main() -> std::io::Result<()> {
+///     let mut dir = env::temp_dir();
+///     dir.push("foo.txt");
 ///
-/// let f = File::create(dir)?;
-/// # Ok(())
-/// # }
+///     let f = File::create(dir)?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn temp_dir() -> PathBuf {
@@ -723,10 +723,10 @@ pub fn args_os() -> ArgsOs {
     ArgsOs { inner: sys::args::args() }
 }
 
-#[stable(feature = "env_unimpl_send_sync", since = "1.25.0")]
+#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
 impl !Send for Args {}
 
-#[stable(feature = "env_unimpl_send_sync", since = "1.25.0")]
+#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
 impl !Sync for Args {}
 
 #[stable(feature = "env", since = "1.0.0")]
@@ -760,10 +760,10 @@ impl fmt::Debug for Args {
     }
 }
 
-#[stable(feature = "env_unimpl_send_sync", since = "1.25.0")]
+#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
 impl !Send for ArgsOs {}
 
-#[stable(feature = "env_unimpl_send_sync", since = "1.25.0")]
+#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
 impl !Sync for ArgsOs {}
 
 #[stable(feature = "env", since = "1.0.0")]
diff --git a/ctr-std/src/error.rs b/ctr-std/src/error.rs
index eb5022a..3c20992 100644
--- a/ctr-std/src/error.rs
+++ b/ctr-std/src/error.rs
@@ -51,14 +51,13 @@
 // coherence challenge (e.g., specialization, neg impls, etc) we can
 // reconsider what crate these items belong in.
 
-use alloc::allocator;
 use any::TypeId;
 use borrow::Cow;
 use cell;
 use char;
-use convert;
 use core::array;
 use fmt::{self, Debug, Display};
+use heap::{AllocErr, LayoutErr, CannotReallocInPlace};
 use mem::transmute;
 use num;
 use str;
@@ -234,7 +233,7 @@ impl<'a> From<Cow<'a, str>> for Box<Error> {
     }
 }
 
-#[unstable(feature = "never_type", issue = "35121")]
+#[stable(feature = "never_type", since = "1.26.0")]
 impl Error for ! {
     fn description(&self) -> &str { *self }
 }
@@ -242,18 +241,27 @@ impl Error for ! {
 #[unstable(feature = "allocator_api",
            reason = "the precise API and guarantees it provides may be tweaked.",
            issue = "32838")]
-impl Error for allocator::AllocErr {
+impl Error for AllocErr {
     fn description(&self) -> &str {
-        allocator::AllocErr::description(self)
+        "memory allocation failed"
     }
 }
 
 #[unstable(feature = "allocator_api",
            reason = "the precise API and guarantees it provides may be tweaked.",
            issue = "32838")]
-impl Error for allocator::CannotReallocInPlace {
+impl Error for LayoutErr {
     fn description(&self) -> &str {
-        allocator::CannotReallocInPlace::description(self)
+        "invalid parameters to Layout::from_size_align"
+    }
+}
+
+#[unstable(feature = "allocator_api",
+           reason = "the precise API and guarantees it provides may be tweaked.",
+           issue = "32838")]
+impl Error for CannotReallocInPlace {
+    fn description(&self) -> &str {
+        CannotReallocInPlace::description(self)
     }
 }
 
@@ -276,14 +284,14 @@ impl Error for num::ParseIntError {
     }
 }
 
-#[unstable(feature = "try_from", issue = "33417")]
+#[stable(feature = "try_from", since = "1.26.0")]
 impl Error for num::TryFromIntError {
     fn description(&self) -> &str {
         self.__description()
     }
 }
 
-#[unstable(feature = "try_from", issue = "33417")]
+#[stable(feature = "try_from", since = "1.26.0")]
 impl Error for array::TryFromSliceError {
     fn description(&self) -> &str {
         self.__description()
@@ -357,7 +365,7 @@ impl Error for cell::BorrowMutError {
     }
 }
 
-#[unstable(feature = "try_from", issue = "33417")]
+#[stable(feature = "try_from", since = "1.26.0")]
 impl Error for char::CharTryFromError {
     fn description(&self) -> &str {
         "converted integer out of range for `char`"
@@ -371,14 +379,6 @@ impl Error for char::ParseCharError {
     }
 }
 
-#[unstable(feature = "try_from", issue = "33417")]
-impl Error for convert::Infallible {
-    fn description(&self) -> &str {
-        match *self {
-        }
-    }
-}
-
 // copied from any.rs
 impl Error + 'static {
     /// Returns true if the boxed type is the same as `T`
diff --git a/ctr-std/src/f32.rs b/ctr-std/src/f32.rs
index a760922..ca39089 100644
--- a/ctr-std/src/f32.rs
+++ b/ctr-std/src/f32.rs
@@ -329,6 +329,57 @@ impl f32 {
         unsafe { intrinsics::fmaf32(self, a, b) }
     }
 
+    /// Calculates Euclidean division, the matching method for `mod_euc`.
+    ///
+    /// This computes the integer `n` such that
+    /// `self = n * rhs + self.mod_euc(rhs)`.
+    /// In other words, the result is `self / rhs` rounded to the integer `n`
+    /// such that `self >= n * rhs`.
+    ///
+    /// ```
+    /// #![feature(euclidean_division)]
+    /// let a: f32 = 7.0;
+    /// let b = 4.0;
+    /// assert_eq!(a.div_euc(b), 1.0); // 7.0 > 4.0 * 1.0
+    /// assert_eq!((-a).div_euc(b), -2.0); // -7.0 >= 4.0 * -2.0
+    /// assert_eq!(a.div_euc(-b), -1.0); // 7.0 >= -4.0 * -1.0
+    /// assert_eq!((-a).div_euc(-b), 2.0); // -7.0 >= -4.0 * 2.0
+    /// ```
+    #[inline]
+    #[unstable(feature = "euclidean_division", issue = "49048")]
+    pub fn div_euc(self, rhs: f32) -> f32 {
+        let q = (self / rhs).trunc();
+        if self % rhs < 0.0 {
+            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 }
+        }
+        q
+    }
+
+    /// Calculates the Euclidean modulo (self mod rhs), which is never negative.
+    ///
+    /// In particular, the result `n` satisfies `0 <= n < rhs.abs()`.
+    ///
+    /// ```
+    /// #![feature(euclidean_division)]
+    /// let a: f32 = 7.0;
+    /// let b = 4.0;
+    /// assert_eq!(a.mod_euc(b), 3.0);
+    /// assert_eq!((-a).mod_euc(b), 1.0);
+    /// assert_eq!(a.mod_euc(-b), 3.0);
+    /// assert_eq!((-a).mod_euc(-b), 1.0);
+    /// ```
+    #[inline]
+    #[unstable(feature = "euclidean_division", issue = "49048")]
+    pub fn mod_euc(self, rhs: f32) -> f32 {
+        let r = self % rhs;
+        if r < 0.0 {
+            r + rhs.abs()
+        } else {
+            r
+        }
+    }
+
+
     /// Takes the reciprocal (inverse) of a number, `1/x`.
     ///
     /// ```
@@ -780,7 +831,7 @@ impl f32 {
         unsafe { cmath::atanf(self) }
     }
 
-    /// Computes the four quadrant arctangent of `self` (`y`) and `other` (`x`).
+    /// Computes the four quadrant arctangent of `self` (`y`) and `other` (`x`) in radians.
     ///
     /// * `x = 0`, `y = 0`: `0`
     /// * `x >= 0`: `arctan(y/x)` -> `[-pi/2, pi/2]`
@@ -791,12 +842,13 @@ impl f32 {
     /// use std::f32;
     ///
     /// let pi = f32::consts::PI;
-    /// // All angles from horizontal right (+x)
-    /// // 45 deg counter-clockwise
+    /// // Positive angles measured counter-clockwise
+    /// // from positive x axis
+    /// // -pi/4 radians (45 deg clockwise)
     /// let x1 = 3.0f32;
     /// let y1 = -3.0f32;
     ///
-    /// // 135 deg clockwise
+    /// // 3pi/4 radians (135 deg counter-clockwise)
     /// let x2 = -3.0f32;
     /// let y2 = 3.0f32;
     ///
diff --git a/ctr-std/src/f64.rs b/ctr-std/src/f64.rs
index 6f34f17..a958567 100644
--- a/ctr-std/src/f64.rs
+++ b/ctr-std/src/f64.rs
@@ -315,6 +315,56 @@ impl f64 {
         unsafe { intrinsics::fmaf64(self, a, b) }
     }
 
+    /// Calculates Euclidean division, the matching method for `mod_euc`.
+    ///
+    /// This computes the integer `n` such that
+    /// `self = n * rhs + self.mod_euc(rhs)`.
+    /// In other words, the result is `self / rhs` rounded to the integer `n`
+    /// such that `self >= n * rhs`.
+    ///
+    /// ```
+    /// #![feature(euclidean_division)]
+    /// let a: f64 = 7.0;
+    /// let b = 4.0;
+    /// assert_eq!(a.div_euc(b), 1.0); // 7.0 > 4.0 * 1.0
+    /// assert_eq!((-a).div_euc(b), -2.0); // -7.0 >= 4.0 * -2.0
+    /// assert_eq!(a.div_euc(-b), -1.0); // 7.0 >= -4.0 * -1.0
+    /// assert_eq!((-a).div_euc(-b), 2.0); // -7.0 >= -4.0 * 2.0
+    /// ```
+    #[inline]
+    #[unstable(feature = "euclidean_division", issue = "49048")]
+    pub fn div_euc(self, rhs: f64) -> f64 {
+        let q = (self / rhs).trunc();
+        if self % rhs < 0.0 {
+            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 }
+        }
+        q
+    }
+
+    /// Calculates the Euclidean modulo (self mod rhs), which is never negative.
+    ///
+    /// In particular, the result `n` satisfies `0 <= n < rhs.abs()`.
+    ///
+    /// ```
+    /// #![feature(euclidean_division)]
+    /// let a: f64 = 7.0;
+    /// let b = 4.0;
+    /// assert_eq!(a.mod_euc(b), 3.0);
+    /// assert_eq!((-a).mod_euc(b), 1.0);
+    /// assert_eq!(a.mod_euc(-b), 3.0);
+    /// assert_eq!((-a).mod_euc(-b), 1.0);
+    /// ```
+    #[inline]
+    #[unstable(feature = "euclidean_division", issue = "49048")]
+    pub fn mod_euc(self, rhs: f64) -> f64 {
+        let r = self % rhs;
+        if r < 0.0 {
+            r + rhs.abs()
+        } else {
+            r
+        }
+    }
+
     /// Takes the reciprocal (inverse) of a number, `1/x`.
     ///
     /// ```
@@ -716,7 +766,7 @@ impl f64 {
         unsafe { cmath::atan(self) }
     }
 
-    /// Computes the four quadrant arctangent of `self` (`y`) and `other` (`x`).
+    /// Computes the four quadrant arctangent of `self` (`y`) and `other` (`x`) in radians.
     ///
     /// * `x = 0`, `y = 0`: `0`
     /// * `x >= 0`: `arctan(y/x)` -> `[-pi/2, pi/2]`
@@ -727,12 +777,13 @@ impl f64 {
     /// use std::f64;
     ///
     /// let pi = f64::consts::PI;
-    /// // All angles from horizontal right (+x)
-    /// // 45 deg counter-clockwise
+    /// // Positive angles measured counter-clockwise
+    /// // from positive x axis
+    /// // -pi/4 radians (45 deg clockwise)
     /// let x1 = 3.0_f64;
     /// let y1 = -3.0_f64;
     ///
-    /// // 135 deg clockwise
+    /// // 3pi/4 radians (135 deg counter-clockwise)
     /// let x2 = -3.0_f64;
     /// let y2 = 3.0_f64;
     ///
diff --git a/ctr-std/src/ffi/c_str.rs b/ctr-std/src/ffi/c_str.rs
index a19fe82..c88c2bc 100644
--- a/ctr-std/src/ffi/c_str.rs
+++ b/ctr-std/src/ffi/c_str.rs
@@ -91,7 +91,7 @@ use sys;
 ///
 /// # Examples
 ///
-/// ```no_run
+/// ```ignore (extern-declaration)
 /// # fn main() {
 /// use std::ffi::CString;
 /// use std::os::raw::c_char;
@@ -150,7 +150,7 @@ pub struct CString {
 ///
 /// Inspecting a foreign C string:
 ///
-/// ```no_run
+/// ```ignore (extern-declaration)
 /// use std::ffi::CStr;
 /// use std::os::raw::c_char;
 ///
@@ -164,7 +164,7 @@ pub struct CString {
 ///
 /// Passing a Rust-originating C string:
 ///
-/// ```no_run
+/// ```ignore (extern-declaration)
 /// use std::ffi::{CString, CStr};
 /// use std::os::raw::c_char;
 ///
@@ -180,7 +180,7 @@ pub struct CString {
 ///
 /// Converting a foreign C string into a Rust [`String`]:
 ///
-/// ```no_run
+/// ```ignore (extern-declaration)
 /// use std::ffi::CStr;
 /// use std::os::raw::c_char;
 ///
@@ -307,7 +307,7 @@ impl CString {
     ///
     /// # Examples
     ///
-    /// ```no_run
+    /// ```ignore (extern-declaration)
     /// use std::ffi::CString;
     /// use std::os::raw::c_char;
     ///
@@ -389,7 +389,7 @@ impl CString {
     /// Create a `CString`, pass ownership to an `extern` function (via raw pointer), then retake
     /// ownership with `from_raw`:
     ///
-    /// ```no_run
+    /// ```ignore (extern-declaration)
     /// use std::ffi::CString;
     /// use std::os::raw::c_char;
     ///
@@ -875,6 +875,8 @@ impl CStr {
     ///   `ptr`.
     /// * There is no guarantee that the memory pointed to by `ptr` contains a
     ///   valid nul terminator byte at the end of the string.
+    /// * It is not guaranteed that the memory pointed by `ptr` won't change
+    ///   before the `CStr` has been destroyed.
     ///
     /// > **Note**: This operation is intended to be a 0-cost cast but it is
     /// > currently implemented with an up-front calculation of the length of
@@ -882,7 +884,7 @@ impl CStr {
     ///
     /// # Examples
     ///
-    /// ```no_run
+    /// ```ignore (extern-declaration)
     /// # fn main() {
     /// use std::ffi::CStr;
     /// use std::os::raw::c_char;
@@ -1026,9 +1028,9 @@ impl CStr {
     /// The returned slice will **not** contain the trailing nul terminator that this C
     /// string has.
     ///
-    /// > **Note**: This method is currently implemented as a 0-cost cast, but
-    /// > it is planned to alter its definition in the future to perform the
-    /// > length calculation whenever this method is called.
+    /// > **Note**: This method is currently implemented as a constant-time
+    /// > cast, but it is planned to alter its definition in the future to
+    /// > perform the length calculation whenever this method is called.
     ///
     /// # Examples
     ///
@@ -1077,9 +1079,9 @@ impl CStr {
     /// it will return an error with details of where UTF-8 validation failed.
     ///
     /// > **Note**: This method is currently implemented to check for validity
-    /// > after a 0-cost cast, but it is planned to alter its definition in the
-    /// > future to perform the length calculation in addition to the UTF-8
-    /// > check whenever this method is called.
+    /// > after a constant-time cast, but it is planned to alter its definition
+    /// > in the future to perform the length calculation in addition to the
+    /// > UTF-8 check whenever this method is called.
     ///
     /// [`&str`]: ../primitive.str.html
     ///
@@ -1110,9 +1112,9 @@ impl CStr {
     /// with the result.
     ///
     /// > **Note**: This method is currently implemented to check for validity
-    /// > after a 0-cost cast, but it is planned to alter its definition in the
-    /// > future to perform the length calculation in addition to the UTF-8
-    /// > check whenever this method is called.
+    /// > after a constant-time cast, but it is planned to alter its definition
+    /// > in the future to perform the length calculation in addition to the
+    /// > UTF-8 check whenever this method is called.
     ///
     /// [`Cow`]: ../borrow/enum.Cow.html
     /// [`Borrowed`]: ../borrow/enum.Cow.html#variant.Borrowed
diff --git a/ctr-std/src/ffi/os_str.rs b/ctr-std/src/ffi/os_str.rs
index 3959e85..7520121 100644
--- a/ctr-std/src/ffi/os_str.rs
+++ b/ctr-std/src/ffi/os_str.rs
@@ -295,6 +295,36 @@ impl OsString {
         self.inner.shrink_to_fit()
     }
 
+    /// Shrinks the capacity of the `OsString` with a lower bound.
+    ///
+    /// The capacity will remain at least as large as both the length
+    /// and the supplied value.
+    ///
+    /// Panics if the current capacity is smaller than the supplied
+    /// minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(shrink_to)]
+    /// use std::ffi::OsString;
+    ///
+    /// let mut s = OsString::from("foo");
+    ///
+    /// s.reserve(100);
+    /// assert!(s.capacity() >= 100);
+    ///
+    /// s.shrink_to(10);
+    /// assert!(s.capacity() >= 10);
+    /// s.shrink_to(0);
+    /// assert!(s.capacity() >= 3);
+    /// ```
+    #[inline]
+    #[unstable(feature = "shrink_to", reason = "new API", issue="0")]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.inner.shrink_to(min_capacity)
+    }
+
     /// Converts this `OsString` into a boxed [`OsStr`].
     ///
     /// [`OsStr`]: struct.OsStr.html
diff --git a/ctr-std/src/fs.rs b/ctr-std/src/fs.rs
index d1f3ccb..7bd1adc 100644
--- a/ctr-std/src/fs.rs
+++ b/ctr-std/src/fs.rs
@@ -41,11 +41,11 @@ use time::SystemTime;
 /// use std::fs::File;
 /// use std::io::prelude::*;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let mut file = File::create("foo.txt")?;
-/// file.write_all(b"Hello, world!")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     let mut file = File::create("foo.txt")?;
+///     file.write_all(b"Hello, world!")?;
+///     Ok(())
+/// }
 /// ```
 ///
 /// Read the contents of a file into a [`String`]:
@@ -54,13 +54,13 @@ use time::SystemTime;
 /// use std::fs::File;
 /// use std::io::prelude::*;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let mut file = File::open("foo.txt")?;
-/// let mut contents = String::new();
-/// file.read_to_string(&mut contents)?;
-/// assert_eq!(contents, "Hello, world!");
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     let mut file = File::open("foo.txt")?;
+///     let mut contents = String::new();
+///     file.read_to_string(&mut contents)?;
+///     assert_eq!(contents, "Hello, world!");
+///     Ok(())
+/// }
 /// ```
 ///
 /// It can be more efficient to read the contents of a file with a buffered
@@ -71,19 +71,28 @@ use time::SystemTime;
 /// use std::io::BufReader;
 /// use std::io::prelude::*;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let file = File::open("foo.txt")?;
-/// let mut buf_reader = BufReader::new(file);
-/// let mut contents = String::new();
-/// buf_reader.read_to_string(&mut contents)?;
-/// assert_eq!(contents, "Hello, world!");
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     let file = File::open("foo.txt")?;
+///     let mut buf_reader = BufReader::new(file);
+///     let mut contents = String::new();
+///     buf_reader.read_to_string(&mut contents)?;
+///     assert_eq!(contents, "Hello, world!");
+///     Ok(())
+/// }
 /// ```
 ///
+/// Note that, although read and write methods require a `&mut File`, because
+/// of the interfaces for [`Read`] and [`Write`], the holder of a `&File` can
+/// still modify the file, either through methods that take `&File` or by
+/// retrieving the underlying OS object and modifying the file that way.
+/// Additionally, many operating systems allow concurrent modification of files
+/// by different processes. Avoid assuming that holding a `&File` means that the
+/// file will not change.
+///
 /// [`Seek`]: ../io/trait.Seek.html
 /// [`String`]: ../string/struct.String.html
 /// [`Read`]: ../io/trait.Read.html
+/// [`Write`]: ../io/trait.Write.html
 /// [`BufReader<R>`]: ../io/struct.BufReader.html
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct File {
@@ -222,7 +231,9 @@ fn initial_buffer_size(file: &File) -> usize {
 /// Read the entire contents of a file into a bytes vector.
 ///
 /// This is a convenience function for using [`File::open`] and [`read_to_end`]
-/// with fewer imports and without an intermediate variable.
+/// with fewer imports and without an intermediate variable.  It pre-allocates a
+/// buffer based on the file size when available, so it is generally faster than
+/// reading into a vector created with `Vec::new()`.
 ///
 /// [`File::open`]: struct.File.html#method.open
 /// [`read_to_end`]: ../io/trait.Read.html#method.read_to_end
@@ -242,17 +253,15 @@ fn initial_buffer_size(file: &File) -> usize {
 /// # Examples
 ///
 /// ```no_run
-/// #![feature(fs_read_write)]
-///
 /// use std::fs;
 /// use std::net::SocketAddr;
 ///
-/// # fn foo() -> Result<(), Box<std::error::Error + 'static>> {
-/// let foo: SocketAddr = String::from_utf8_lossy(&fs::read("address.txt")?).parse()?;
-/// # Ok(())
-/// # }
+/// fn main() -> Result<(), Box<std::error::Error + 'static>> {
+///     let foo: SocketAddr = String::from_utf8_lossy(&fs::read("address.txt")?).parse()?;
+///     Ok(())
+/// }
 /// ```
-#[unstable(feature = "fs_read_write", issue = "46588")]
+#[stable(feature = "fs_read_write_bytes", since = "1.26.0")]
 pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
     let mut file = File::open(path)?;
     let mut bytes = Vec::with_capacity(initial_buffer_size(&file));
@@ -263,7 +272,9 @@ pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
 /// Read the entire contents of a file into a string.
 ///
 /// This is a convenience function for using [`File::open`] and [`read_to_string`]
-/// with fewer imports and without an intermediate variable.
+/// with fewer imports and without an intermediate variable.  It pre-allocates a
+/// buffer based on the file size when available, so it is generally faster than
+/// reading into a string created with `String::new()`.
 ///
 /// [`File::open`]: struct.File.html#method.open
 /// [`read_to_string`]: ../io/trait.Read.html#method.read_to_string
@@ -289,13 +300,13 @@ pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
 /// use std::fs;
 /// use std::net::SocketAddr;
 ///
-/// # fn foo() -> Result<(), Box<std::error::Error + 'static>> {
-/// let foo: SocketAddr = fs::read_string("address.txt")?.parse()?;
-/// # Ok(())
-/// # }
+/// fn main() -> Result<(), Box<std::error::Error + 'static>> {
+///     let foo: SocketAddr = fs::read_to_string("address.txt")?.parse()?;
+///     Ok(())
+/// }
 /// ```
-#[unstable(feature = "fs_read_write", issue = "46588")]
-pub fn read_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
+#[stable(feature = "fs_read_write", since = "1.26.0")]
+pub fn read_to_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
     let mut file = File::open(path)?;
     let mut string = String::with_capacity(initial_buffer_size(&file));
     file.read_to_string(&mut string)?;
@@ -316,16 +327,14 @@ pub fn read_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
 /// # Examples
 ///
 /// ```no_run
-/// #![feature(fs_read_write)]
-///
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::write("foo.txt", b"Lorem ipsum")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::write("foo.txt", b"Lorem ipsum")?;
+///     Ok(())
+/// }
 /// ```
-#[unstable(feature = "fs_read_write", issue = "46588")]
+#[stable(feature = "fs_read_write_bytes", since = "1.26.0")]
 pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> {
     File::create(path)?.write_all(contents.as_ref())
 }
@@ -347,7 +356,7 @@ impl File {
     /// ```no_run
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
+    /// fn main() -> std::io::Result<()> {
     /// let mut f = File::open("foo.txt")?;
     /// # Ok(())
     /// # }
@@ -371,10 +380,10 @@ impl File {
     /// ```no_run
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = File::create("foo.txt")?;
-    /// # Ok(())
-    /// # }
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut f = File::create("foo.txt")?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn create<P: AsRef<Path>>(path: P) -> io::Result<File> {
@@ -392,13 +401,13 @@ impl File {
     /// use std::fs::File;
     /// use std::io::prelude::*;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = File::create("foo.txt")?;
-    /// f.write_all(b"Hello, world!")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut f = File::create("foo.txt")?;
+    ///     f.write_all(b"Hello, world!")?;
     ///
-    /// f.sync_all()?;
-    /// # Ok(())
-    /// # }
+    ///     f.sync_all()?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn sync_all(&self) -> io::Result<()> {
@@ -423,13 +432,13 @@ impl File {
     /// use std::fs::File;
     /// use std::io::prelude::*;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = File::create("foo.txt")?;
-    /// f.write_all(b"Hello, world!")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut f = File::create("foo.txt")?;
+    ///     f.write_all(b"Hello, world!")?;
     ///
-    /// f.sync_data()?;
-    /// # Ok(())
-    /// # }
+    ///     f.sync_data()?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn sync_data(&self) -> io::Result<()> {
@@ -444,6 +453,10 @@ impl File {
     /// will be extended to `size` and have all of the intermediate data filled
     /// in with 0s.
     ///
+    /// The file's cursor isn't changed. In particular, if the cursor was at the
+    /// end and the file is shrunk using this operation, the cursor will now be
+    /// past the end.
+    ///
     /// # Errors
     ///
     /// This function will return an error if the file is not opened for writing.
@@ -453,12 +466,15 @@ impl File {
     /// ```no_run
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = File::create("foo.txt")?;
-    /// f.set_len(10)?;
-    /// # Ok(())
-    /// # }
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut f = File::create("foo.txt")?;
+    ///     f.set_len(10)?;
+    ///     Ok(())
+    /// }
     /// ```
+    ///
+    /// Note that this method alters the content of the underlying file, even
+    /// though it takes `&self` rather than `&mut self`.
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn set_len(&self, size: u64) -> io::Result<()> {
         self.inner.truncate(size)
@@ -471,33 +487,55 @@ impl File {
     /// ```no_run
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
-    /// let metadata = f.metadata()?;
-    /// # Ok(())
-    /// # }
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
+    ///     let metadata = f.metadata()?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn metadata(&self) -> io::Result<Metadata> {
         self.inner.file_attr().map(Metadata)
     }
 
-    /// Creates a new independently owned handle to the underlying file.
-    ///
-    /// The returned `File` is a reference to the same state that this object
-    /// references. Both handles will read and write with the same cursor
-    /// position.
+    /// Create a new `File` instance that shares the same underlying file handle
+    /// as the existing `File` instance. Reads, writes, and seeks will affect
+    /// both `File` instances simultaneously.
     ///
     /// # Examples
     ///
+    /// Create two handles for a file named `foo.txt`:
+    ///
     /// ```no_run
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
-    /// let file_copy = f.try_clone()?;
-    /// # Ok(())
-    /// # }
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut file = File::open("foo.txt")?;
+    ///     let file_copy = file.try_clone()?;
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// Assuming there’s a file named `foo.txt` with contents `abcdef\n`, create
+    /// two handles, seek one of them, and read the remaining bytes from the
+    /// other handle:
+    ///
+    /// ```no_run
+    /// use std::fs::File;
+    /// use std::io::SeekFrom;
+    /// use std::io::prelude::*;
+    ///
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut file = File::open("foo.txt")?;
+    ///     let mut file_copy = file.try_clone()?;
+    ///
+    ///     file.seek(SeekFrom::Start(3))?;
+    ///
+    ///     let mut contents = vec![];
+    ///     file_copy.read_to_end(&mut contents)?;
+    ///     assert_eq!(contents, b"def\n");
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "file_try_clone", since = "1.9.0")]
     pub fn try_clone(&self) -> io::Result<File> {
@@ -524,17 +562,20 @@ impl File {
     ///
     /// # Examples
     ///
+    /// ```no_run
+    /// fn main() -> std::io::Result<()> {
+    ///     use std::fs::File;
+    ///
+    ///     let file = File::open("foo.txt")?;
+    ///     let mut perms = file.metadata()?.permissions();
+    ///     perms.set_readonly(true);
+    ///     file.set_permissions(perms)?;
+    ///     Ok(())
+    /// }
     /// ```
-    /// # fn foo() -> std::io::Result<()> {
-    /// use std::fs::File;
     ///
-    /// let file = File::open("foo.txt")?;
-    /// let mut perms = file.metadata()?.permissions();
-    /// perms.set_readonly(true);
-    /// file.set_permissions(perms)?;
-    /// # Ok(())
-    /// # }
-    /// ```
+    /// Note that this method alters the permissions of the underlying file,
+    /// even though it takes `&self` rather than `&mut self`.
     #[stable(feature = "set_permissions_atomic", since = "1.16.0")]
     pub fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
         self.inner.set_permissions(perm.0)
@@ -850,51 +891,63 @@ impl Metadata {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
-    /// use std::fs;
+    /// ```no_run
+    /// fn main() -> std::io::Result<()> {
+    ///     use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
+    ///     let metadata = fs::metadata("foo.txt")?;
     ///
-    /// println!("{:?}", metadata.file_type());
-    /// # Ok(())
-    /// # }
+    ///     println!("{:?}", metadata.file_type());
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "file_type", since = "1.1.0")]
     pub fn file_type(&self) -> FileType {
         FileType(self.0.file_type())
     }
 
-    /// Returns whether this metadata is for a directory.
+    /// Returns whether this metadata is for a directory. The
+    /// result is mutually exclusive to the result of
+    /// [`is_file`], and will be false for symlink metadata
+    /// obtained from [`symlink_metadata`].
+    ///
+    /// [`is_file`]: struct.Metadata.html#method.is_file
+    /// [`symlink_metadata`]: fn.symlink_metadata.html
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
-    /// use std::fs;
+    /// ```no_run
+    /// fn main() -> std::io::Result<()> {
+    ///     use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
+    ///     let metadata = fs::metadata("foo.txt")?;
     ///
-    /// assert!(!metadata.is_dir());
-    /// # Ok(())
-    /// # }
+    ///     assert!(!metadata.is_dir());
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_dir(&self) -> bool { self.file_type().is_dir() }
 
-    /// Returns whether this metadata is for a regular file.
+    /// Returns whether this metadata is for a regular file. The
+    /// result is mutually exclusive to the result of
+    /// [`is_dir`], and will be false for symlink metadata
+    /// obtained from [`symlink_metadata`].
+    ///
+    /// [`is_dir`]: struct.Metadata.html#method.is_dir
+    /// [`symlink_metadata`]: fn.symlink_metadata.html
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
+    /// ```no_run
     /// use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let metadata = fs::metadata("foo.txt")?;
     ///
-    /// assert!(metadata.is_file());
-    /// # Ok(())
-    /// # }
+    ///     assert!(metadata.is_file());
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_file(&self) -> bool { self.file_type().is_file() }
@@ -903,15 +956,15 @@ impl Metadata {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
+    /// ```no_run
     /// use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let metadata = fs::metadata("foo.txt")?;
     ///
-    /// assert_eq!(0, metadata.len());
-    /// # Ok(())
-    /// # }
+    ///     assert_eq!(0, metadata.len());
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> u64 { self.0.size() }
@@ -920,15 +973,15 @@ impl Metadata {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
+    /// ```no_run
     /// use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let metadata = fs::metadata("foo.txt")?;
     ///
-    /// assert!(!metadata.permissions().readonly());
-    /// # Ok(())
-    /// # }
+    ///     assert!(!metadata.permissions().readonly());
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn permissions(&self) -> Permissions {
@@ -947,19 +1000,19 @@ impl Metadata {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
+    /// ```no_run
     /// use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let metadata = fs::metadata("foo.txt")?;
     ///
-    /// if let Ok(time) = metadata.modified() {
-    ///     println!("{:?}", time);
-    /// } else {
-    ///     println!("Not supported on this platform");
+    ///     if let Ok(time) = metadata.modified() {
+    ///         println!("{:?}", time);
+    ///     } else {
+    ///         println!("Not supported on this platform");
+    ///     }
+    ///     Ok(())
     /// }
-    /// # Ok(())
-    /// # }
     /// ```
     #[stable(feature = "fs_time", since = "1.10.0")]
     pub fn modified(&self) -> io::Result<SystemTime> {
@@ -982,26 +1035,26 @@ impl Metadata {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
+    /// ```no_run
     /// use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let metadata = fs::metadata("foo.txt")?;
     ///
-    /// if let Ok(time) = metadata.accessed() {
-    ///     println!("{:?}", time);
-    /// } else {
-    ///     println!("Not supported on this platform");
+    ///     if let Ok(time) = metadata.accessed() {
+    ///         println!("{:?}", time);
+    ///     } else {
+    ///         println!("Not supported on this platform");
+    ///     }
+    ///     Ok(())
     /// }
-    /// # Ok(())
-    /// # }
     /// ```
     #[stable(feature = "fs_time", since = "1.10.0")]
     pub fn accessed(&self) -> io::Result<SystemTime> {
         self.0.accessed().map(FromInner::from_inner)
     }
 
-    /// Returns the creation time listed in the this metadata.
+    /// Returns the creation time listed in this metadata.
     ///
     /// The returned value corresponds to the `birthtime` field of `stat` on
     /// Unix platforms and the `ftCreationTime` field on Windows platforms.
@@ -1013,19 +1066,19 @@ impl Metadata {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
+    /// ```no_run
     /// use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let metadata = fs::metadata("foo.txt")?;
     ///
-    /// if let Ok(time) = metadata.created() {
-    ///     println!("{:?}", time);
-    /// } else {
-    ///     println!("Not supported on this platform");
+    ///     if let Ok(time) = metadata.created() {
+    ///         println!("{:?}", time);
+    ///     } else {
+    ///         println!("Not supported on this platform");
+    ///     }
+    ///     Ok(())
     /// }
-    /// # Ok(())
-    /// # }
     /// ```
     #[stable(feature = "fs_time", since = "1.10.0")]
     pub fn created(&self) -> io::Result<SystemTime> {
@@ -1057,16 +1110,16 @@ impl Permissions {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = File::create("foo.txt")?;
-    /// let metadata = f.metadata()?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut f = File::create("foo.txt")?;
+    ///     let metadata = f.metadata()?;
     ///
-    /// assert_eq!(false, metadata.permissions().readonly());
-    /// # Ok(())
-    /// # }
+    ///     assert_eq!(false, metadata.permissions().readonly());
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn readonly(&self) -> bool { self.0.readonly() }
@@ -1082,23 +1135,23 @@ impl Permissions {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let f = File::create("foo.txt")?;
-    /// let metadata = f.metadata()?;
-    /// let mut permissions = metadata.permissions();
+    /// fn main() -> std::io::Result<()> {
+    ///     let f = File::create("foo.txt")?;
+    ///     let metadata = f.metadata()?;
+    ///     let mut permissions = metadata.permissions();
     ///
-    /// permissions.set_readonly(true);
+    ///     permissions.set_readonly(true);
     ///
-    /// // filesystem doesn't change
-    /// assert_eq!(false, metadata.permissions().readonly());
+    ///     // filesystem doesn't change
+    ///     assert_eq!(false, metadata.permissions().readonly());
     ///
-    /// // just this particular `permissions`.
-    /// assert_eq!(true, permissions.readonly());
-    /// # Ok(())
-    /// # }
+    ///     // just this particular `permissions`.
+    ///     assert_eq!(true, permissions.readonly());
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn set_readonly(&mut self, readonly: bool) {
@@ -1107,43 +1160,58 @@ impl Permissions {
 }
 
 impl FileType {
-    /// Test whether this file type represents a directory.
+    /// Test whether this file type represents a directory. The
+    /// result is mutually exclusive to the results of
+    /// [`is_file`] and [`is_symlink`]; only zero or one of these
+    /// tests may pass.
+    ///
+    /// [`is_file`]: struct.FileType.html#method.is_file
+    /// [`is_symlink`]: struct.FileType.html#method.is_symlink
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
-    /// use std::fs;
+    /// ```no_run
+    /// fn main() -> std::io::Result<()> {
+    ///     use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
-    /// let file_type = metadata.file_type();
+    ///     let metadata = fs::metadata("foo.txt")?;
+    ///     let file_type = metadata.file_type();
     ///
-    /// assert_eq!(file_type.is_dir(), false);
-    /// # Ok(())
-    /// # }
+    ///     assert_eq!(file_type.is_dir(), false);
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "file_type", since = "1.1.0")]
     pub fn is_dir(&self) -> bool { self.0.is_dir() }
 
     /// Test whether this file type represents a regular file.
+    /// The result is  mutually exclusive to the results of
+    /// [`is_dir`] and [`is_symlink`]; only zero or one of these
+    /// tests may pass.
+    ///
+    /// [`is_dir`]: struct.FileType.html#method.is_dir
+    /// [`is_symlink`]: struct.FileType.html#method.is_symlink
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
-    /// use std::fs;
+    /// ```no_run
+    /// fn main() -> std::io::Result<()> {
+    ///     use std::fs;
     ///
-    /// let metadata = fs::metadata("foo.txt")?;
-    /// let file_type = metadata.file_type();
+    ///     let metadata = fs::metadata("foo.txt")?;
+    ///     let file_type = metadata.file_type();
     ///
-    /// assert_eq!(file_type.is_file(), true);
-    /// # Ok(())
-    /// # }
+    ///     assert_eq!(file_type.is_file(), true);
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "file_type", since = "1.1.0")]
     pub fn is_file(&self) -> bool { self.0.is_file() }
 
     /// Test whether this file type represents a symbolic link.
+    /// The result is mutually exclusive to the results of
+    /// [`is_dir`] and [`is_file`]; only zero or one of these
+    /// tests may pass.
     ///
     /// The underlying [`Metadata`] struct needs to be retrieved
     /// with the [`fs::symlink_metadata`] function and not the
@@ -1154,20 +1222,22 @@ impl FileType {
     /// [`Metadata`]: struct.Metadata.html
     /// [`fs::metadata`]: fn.metadata.html
     /// [`fs::symlink_metadata`]: fn.symlink_metadata.html
+    /// [`is_dir`]: struct.FileType.html#method.is_dir
+    /// [`is_file`]: struct.FileType.html#method.is_file
     /// [`is_symlink`]: struct.FileType.html#method.is_symlink
     ///
     /// # Examples
     ///
-    /// ```
-    /// # fn foo() -> std::io::Result<()> {
+    /// ```no_run
     /// use std::fs;
     ///
-    /// let metadata = fs::symlink_metadata("foo.txt")?;
-    /// let file_type = metadata.file_type();
+    /// fn main() -> std::io::Result<()> {
+    ///     let metadata = fs::symlink_metadata("foo.txt")?;
+    ///     let file_type = metadata.file_type();
     ///
-    /// assert_eq!(file_type.is_symlink(), false);
-    /// # Ok(())
-    /// # }
+    ///     assert_eq!(file_type.is_symlink(), false);
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "file_type", since = "1.1.0")]
     pub fn is_symlink(&self) -> bool { self.0.is_symlink() }
@@ -1204,15 +1274,16 @@ impl DirEntry {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::fs;
-    /// # fn foo() -> std::io::Result<()> {
-    /// for entry in fs::read_dir(".")? {
-    ///     let dir = entry?;
-    ///     println!("{:?}", dir.path());
+    ///
+    /// fn main() -> std::io::Result<()> {
+    ///     for entry in fs::read_dir(".")? {
+    ///         let dir = entry?;
+    ///         println!("{:?}", dir.path());
+    ///     }
+    ///     Ok(())
     /// }
-    /// # Ok(())
-    /// # }
     /// ```
     ///
     /// This prints output like:
@@ -1357,13 +1428,13 @@ impl AsInner<fs_imp::DirEntry> for DirEntry {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::remove_file("a.txt")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::remove_file("a.txt")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn remove_file<P: AsRef<Path>>(path: P) -> io::Result<()> {
@@ -1394,14 +1465,14 @@ pub fn remove_file<P: AsRef<Path>>(path: P) -> io::Result<()> {
 ///
 /// # Examples
 ///
-/// ```rust
-/// # fn foo() -> std::io::Result<()> {
+/// ```rust,no_run
 /// use std::fs;
 ///
-/// let attr = fs::metadata("/some/file/path.txt")?;
-/// // inspect attr ...
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     let attr = fs::metadata("/some/file/path.txt")?;
+///     // inspect attr ...
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
@@ -1428,14 +1499,14 @@ pub fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
 ///
 /// # Examples
 ///
-/// ```rust
-/// # fn foo() -> std::io::Result<()> {
+/// ```rust,no_run
 /// use std::fs;
 ///
-/// let attr = fs::symlink_metadata("/some/file/path.txt")?;
-/// // inspect attr ...
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     let attr = fs::symlink_metadata("/some/file/path.txt")?;
+///     // inspect attr ...
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "symlink_metadata", since = "1.1.0")]
 pub fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
@@ -1472,13 +1543,13 @@ pub fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::rename("a.txt", "b.txt")?; // Rename a.txt to b.txt
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::rename("a.txt", "b.txt")?; // Rename a.txt to b.txt
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
@@ -1523,9 +1594,10 @@ pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()>
 /// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::copy("foo.txt", "bar.txt")?;  // Copy foo.txt to bar.txt
-/// # Ok(()) }
+/// fn main() -> std::io::Result<()> {
+///     fs::copy("foo.txt", "bar.txt")?;  // Copy foo.txt to bar.txt
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64> {
@@ -1554,13 +1626,13 @@ pub fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64> {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::hard_link("a.txt", "b.txt")?; // Hard link a.txt to b.txt
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::hard_link("a.txt", "b.txt")?; // Hard link a.txt to b.txt
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn hard_link<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
@@ -1577,13 +1649,13 @@ pub fn hard_link<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<(
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::soft_link("a.txt", "b.txt")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::soft_link("a.txt", "b.txt")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_deprecated(since = "1.1.0",
@@ -1614,13 +1686,13 @@ pub fn soft_link<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<(
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let path = fs::read_link("a.txt")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     let path = fs::read_link("a.txt")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
@@ -1648,13 +1720,13 @@ pub fn read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let path = fs::canonicalize("../a/../foo.txt")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     let path = fs::canonicalize("../a/../foo.txt")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "fs_canonicalize", since = "1.5.0")]
 pub fn canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
@@ -1681,13 +1753,13 @@ pub fn canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::create_dir("/some/dir")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::create_dir("/some/dir")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
@@ -1723,13 +1795,13 @@ pub fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::create_dir_all("/some/dir")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::create_dir_all("/some/dir")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
@@ -1756,13 +1828,13 @@ pub fn create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::remove_dir("/some/dir")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::remove_dir("/some/dir")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
@@ -1790,13 +1862,13 @@ pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::fs;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// fs::remove_dir_all("/some/dir")?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     fs::remove_dir_all("/some/dir")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
@@ -1876,15 +1948,15 @@ pub fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
 ///
 /// # Examples
 ///
-/// ```
-/// # fn foo() -> std::io::Result<()> {
+/// ```no_run
 /// use std::fs;
 ///
-/// let mut perms = fs::metadata("foo.txt")?.permissions();
-/// perms.set_readonly(true);
-/// fs::set_permissions("foo.txt", perms)?;
-/// # Ok(())
-/// # }
+/// fn main() -> std::io::Result<()> {
+///     let mut perms = fs::metadata("foo.txt")?.permissions();
+///     perms.set_readonly(true);
+///     fs::set_permissions("foo.txt", perms)?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "set_permissions", since = "1.1.0")]
 pub fn set_permissions<P: AsRef<Path>>(path: P, perm: Permissions)
@@ -3054,12 +3126,12 @@ mod tests {
         assert!(v == &bytes[..]);
 
         check!(fs::write(&tmpdir.join("not-utf8"), &[0xFF]));
-        error_contains!(fs::read_string(&tmpdir.join("not-utf8")),
+        error_contains!(fs::read_to_string(&tmpdir.join("not-utf8")),
                         "stream did not contain valid UTF-8");
 
         let s = "𐁁𐀓𐀠𐀴𐀍";
         check!(fs::write(&tmpdir.join("utf8"), s.as_bytes()));
-        let string = check!(fs::read_string(&tmpdir.join("utf8")));
+        let string = check!(fs::read_to_string(&tmpdir.join("utf8")));
         assert_eq!(string, s);
     }
 
diff --git a/ctr-std/src/heap.rs b/ctr-std/src/heap.rs
deleted file mode 100644
index 4d5e4df..0000000
--- a/ctr-std/src/heap.rs
+++ /dev/null
@@ -1,175 +0,0 @@
-// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! dox
-
-#![unstable(issue = "32838", feature = "allocator_api")]
-
-pub use alloc::heap::{Heap, Alloc, Layout, Excess, CannotReallocInPlace, AllocErr};
-pub use alloc_system::System;
-
-#[cfg(not(test))]
-#[doc(hidden)]
-#[allow(unused_attributes)]
-pub mod __default_lib_allocator {
-    use super::{System, Layout, Alloc, AllocErr};
-    use ptr;
-
-    // for symbol names src/librustc/middle/allocator.rs
-    // for signatures src/librustc_allocator/lib.rs
-
-    // linkage directives are provided as part of the current compiler allocator
-    // ABI
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_alloc(size: usize,
-                                     align: usize,
-                                     err: *mut u8) -> *mut u8 {
-        let layout = Layout::from_size_align_unchecked(size, align);
-        match System.alloc(layout) {
-            Ok(p) => p,
-            Err(e) => {
-                ptr::write(err as *mut AllocErr, e);
-                0 as *mut u8
-            }
-        }
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_oom(err: *const u8) -> ! {
-        System.oom((*(err as *const AllocErr)).clone())
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_dealloc(ptr: *mut u8,
-                                       size: usize,
-                                       align: usize) {
-        System.dealloc(ptr, Layout::from_size_align_unchecked(size, align))
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_usable_size(layout: *const u8,
-                                           min: *mut usize,
-                                           max: *mut usize) {
-        let pair = System.usable_size(&*(layout as *const Layout));
-        *min = pair.0;
-        *max = pair.1;
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_realloc(ptr: *mut u8,
-                                       old_size: usize,
-                                       old_align: usize,
-                                       new_size: usize,
-                                       new_align: usize,
-                                       err: *mut u8) -> *mut u8 {
-        let old_layout = Layout::from_size_align_unchecked(old_size, old_align);
-        let new_layout = Layout::from_size_align_unchecked(new_size, new_align);
-        match System.realloc(ptr, old_layout, new_layout) {
-            Ok(p) => p,
-            Err(e) => {
-                ptr::write(err as *mut AllocErr, e);
-                0 as *mut u8
-            }
-        }
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_alloc_zeroed(size: usize,
-                                            align: usize,
-                                            err: *mut u8) -> *mut u8 {
-        let layout = Layout::from_size_align_unchecked(size, align);
-        match System.alloc_zeroed(layout) {
-            Ok(p) => p,
-            Err(e) => {
-                ptr::write(err as *mut AllocErr, e);
-                0 as *mut u8
-            }
-        }
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_alloc_excess(size: usize,
-                                            align: usize,
-                                            excess: *mut usize,
-                                            err: *mut u8) -> *mut u8 {
-        let layout = Layout::from_size_align_unchecked(size, align);
-        match System.alloc_excess(layout) {
-            Ok(p) => {
-                *excess = p.1;
-                p.0
-            }
-            Err(e) => {
-                ptr::write(err as *mut AllocErr, e);
-                0 as *mut u8
-            }
-        }
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_realloc_excess(ptr: *mut u8,
-                                              old_size: usize,
-                                              old_align: usize,
-                                              new_size: usize,
-                                              new_align: usize,
-                                              excess: *mut usize,
-                                              err: *mut u8) -> *mut u8 {
-        let old_layout = Layout::from_size_align_unchecked(old_size, old_align);
-        let new_layout = Layout::from_size_align_unchecked(new_size, new_align);
-        match System.realloc_excess(ptr, old_layout, new_layout) {
-            Ok(p) => {
-                *excess = p.1;
-                p.0
-            }
-            Err(e) => {
-                ptr::write(err as *mut AllocErr, e);
-                0 as *mut u8
-            }
-        }
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_grow_in_place(ptr: *mut u8,
-                                             old_size: usize,
-                                             old_align: usize,
-                                             new_size: usize,
-                                             new_align: usize) -> u8 {
-        let old_layout = Layout::from_size_align_unchecked(old_size, old_align);
-        let new_layout = Layout::from_size_align_unchecked(new_size, new_align);
-        match System.grow_in_place(ptr, old_layout, new_layout) {
-            Ok(()) => 1,
-            Err(_) => 0,
-        }
-    }
-
-    #[no_mangle]
-    #[rustc_std_internal_symbol]
-    pub unsafe extern fn __rdl_shrink_in_place(ptr: *mut u8,
-                                               old_size: usize,
-                                               old_align: usize,
-                                               new_size: usize,
-                                               new_align: usize) -> u8 {
-        let old_layout = Layout::from_size_align_unchecked(old_size, old_align);
-        let new_layout = Layout::from_size_align_unchecked(new_size, new_align);
-        match System.shrink_in_place(ptr, old_layout, new_layout) {
-            Ok(()) => 1,
-            Err(_) => 0,
-        }
-    }
-}
diff --git a/ctr-std/src/io/buffered.rs b/ctr-std/src/io/buffered.rs
index 4e7db5f..d6eac74 100644
--- a/ctr-std/src/io/buffered.rs
+++ b/ctr-std/src/io/buffered.rs
@@ -25,26 +25,32 @@ use memchr;
 /// results in a system call. A `BufReader` performs large, infrequent reads on
 /// the underlying [`Read`] and maintains an in-memory buffer of the results.
 ///
+/// `BufReader` can improve the speed of programs that make *small* and
+/// *repeated* read calls to the same file or network socket.  It does not
+/// help when reading very large amounts at once, or reading just one or a few
+/// times.  It also provides no advantage when reading from a source that is
+/// already in memory, like a `Vec<u8>`.
+///
 /// [`Read`]: ../../std/io/trait.Read.html
 /// [`TcpStream::read`]: ../../std/net/struct.TcpStream.html#method.read
 /// [`TcpStream`]: ../../std/net/struct.TcpStream.html
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::io::prelude::*;
 /// use std::io::BufReader;
 /// use std::fs::File;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let f = File::open("log.txt")?;
-/// let mut reader = BufReader::new(f);
+/// fn main() -> std::io::Result<()> {
+///     let f = File::open("log.txt")?;
+///     let mut reader = BufReader::new(f);
 ///
-/// let mut line = String::new();
-/// let len = reader.read_line(&mut line)?;
-/// println!("First line is {} bytes long", len);
-/// # Ok(())
-/// # }
+///     let mut line = String::new();
+///     let len = reader.read_line(&mut line)?;
+///     println!("First line is {} bytes long", len);
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct BufReader<R> {
@@ -59,15 +65,15 @@ impl<R: Read> BufReader<R> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::BufReader;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let f = File::open("log.txt")?;
-    /// let reader = BufReader::new(f);
-    /// # Ok(())
-    /// # }
+    /// fn main() -> std::io::Result<()> {
+    ///     let f = File::open("log.txt")?;
+    ///     let reader = BufReader::new(f);
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(inner: R) -> BufReader<R> {
@@ -80,15 +86,15 @@ impl<R: Read> BufReader<R> {
     ///
     /// Creating a buffer with ten bytes of capacity:
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::BufReader;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let f = File::open("log.txt")?;
-    /// let reader = BufReader::with_capacity(10, f);
-    /// # Ok(())
-    /// # }
+    /// fn main() -> std::io::Result<()> {
+    ///     let f = File::open("log.txt")?;
+    ///     let reader = BufReader::with_capacity(10, f);
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(cap: usize, inner: R) -> BufReader<R> {
@@ -111,17 +117,17 @@ impl<R: Read> BufReader<R> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::BufReader;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let f1 = File::open("log.txt")?;
-    /// let reader = BufReader::new(f1);
+    /// fn main() -> std::io::Result<()> {
+    ///     let f1 = File::open("log.txt")?;
+    ///     let reader = BufReader::new(f1);
     ///
-    /// let f2 = reader.get_ref();
-    /// # Ok(())
-    /// # }
+    ///     let f2 = reader.get_ref();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_ref(&self) -> &R { &self.inner }
@@ -132,17 +138,17 @@ impl<R: Read> BufReader<R> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::BufReader;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let f1 = File::open("log.txt")?;
-    /// let mut reader = BufReader::new(f1);
+    /// fn main() -> std::io::Result<()> {
+    ///     let f1 = File::open("log.txt")?;
+    ///     let mut reader = BufReader::new(f1);
     ///
-    /// let f2 = reader.get_mut();
-    /// # Ok(())
-    /// # }
+    ///     let f2 = reader.get_mut();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut R { &mut self.inner }
@@ -150,26 +156,55 @@ impl<R: Read> BufReader<R> {
     /// Returns `true` if there are no bytes in the internal buffer.
     ///
     /// # Examples
-    /// ```
+    //
+    /// ```no_run
     /// # #![feature(bufreader_is_empty)]
     /// use std::io::BufReader;
     /// use std::io::BufRead;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let f1 = File::open("log.txt")?;
-    /// let mut reader = BufReader::new(f1);
-    /// assert!(reader.is_empty());
+    /// fn main() -> std::io::Result<()> {
+    ///     let f1 = File::open("log.txt")?;
+    ///     let mut reader = BufReader::new(f1);
+    ///     assert!(reader.is_empty());
     ///
-    /// if reader.fill_buf()?.len() > 0 {
-    ///     assert!(!reader.is_empty());
+    ///     if reader.fill_buf()?.len() > 0 {
+    ///         assert!(!reader.is_empty());
+    ///     }
+    ///     Ok(())
     /// }
-    /// # Ok(())
-    /// # }
     /// ```
     #[unstable(feature = "bufreader_is_empty", issue = "45323", reason = "recently added")]
+    #[rustc_deprecated(since = "1.26.0", reason = "use .buffer().is_empty() instead")]
     pub fn is_empty(&self) -> bool {
-        self.pos == self.cap
+        self.buffer().is_empty()
+    }
+
+    /// Returns a reference to the internally buffered data.
+    ///
+    /// Unlike `fill_buf`, this will not attempt to fill the buffer if it is empty.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// # #![feature(bufreader_buffer)]
+    /// use std::io::{BufReader, BufRead};
+    /// use std::fs::File;
+    ///
+    /// fn main() -> std::io::Result<()> {
+    ///     let f = File::open("log.txt")?;
+    ///     let mut reader = BufReader::new(f);
+    ///     assert!(reader.buffer().is_empty());
+    ///
+    ///     if reader.fill_buf()?.len() > 0 {
+    ///         assert!(!reader.buffer().is_empty());
+    ///     }
+    ///     Ok(())
+    /// }
+    /// ```
+    #[unstable(feature = "bufreader_buffer", issue = "45323")]
+    pub fn buffer(&self) -> &[u8] {
+        &self.buf[self.pos..self.cap]
     }
 
     /// Unwraps this `BufReader`, returning the underlying reader.
@@ -178,17 +213,17 @@ impl<R: Read> BufReader<R> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::BufReader;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let f1 = File::open("log.txt")?;
-    /// let reader = BufReader::new(f1);
+    /// fn main() -> std::io::Result<()> {
+    ///     let f1 = File::open("log.txt")?;
+    ///     let reader = BufReader::new(f1);
     ///
-    /// let f2 = reader.into_inner();
-    /// # Ok(())
-    /// # }
+    ///     let f2 = reader.into_inner();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_inner(self) -> R { self.inner }
@@ -293,7 +328,7 @@ impl<R: Seek> Seek for BufReader<R> {
     /// where `n` minus the internal buffer length overflows an `i64`, two
     /// seeks will be performed instead of one. If the second seek returns
     /// `Err`, the underlying reader will be left at the same position it would
-    /// have if you seeked to `SeekFrom::Current(0)`.
+    /// have if you called `seek` with `SeekFrom::Current(0)`.
     ///
     /// [`seek_relative`]: #method.seek_relative
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
@@ -330,6 +365,12 @@ impl<R: Seek> Seek for BufReader<R> {
 /// `BufWriter` keeps an in-memory buffer of data and writes it to an underlying
 /// writer in large, infrequent batches.
 ///
+/// `BufWriter` can improve the speed of programs that make *small* and
+/// *repeated* write calls to the same file or network socket.  It does not
+/// help when writing very large amounts at once, or writing just one or a few
+/// times.  It also provides no advantage when writing to a destination that is
+/// in memory, like a `Vec<u8>`.
+///
 /// When the `BufWriter` is dropped, the contents of its buffer will be written
 /// out. However, any errors that happen in the process of flushing the buffer
 /// when the writer is dropped will be ignored. Code that wishes to handle such
@@ -696,34 +737,34 @@ impl<W> fmt::Display for IntoInnerError<W> {
 /// We can use `LineWriter` to write one line at a time, significantly
 /// reducing the number of actual writes to the file.
 ///
-/// ```
+/// ```no_run
 /// use std::fs::File;
 /// use std::io::prelude::*;
 /// use std::io::LineWriter;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let road_not_taken = b"I shall be telling this with a sigh
+/// fn main() -> std::io::Result<()> {
+///     let road_not_taken = b"I shall be telling this with a sigh
 /// Somewhere ages and ages hence:
 /// Two roads diverged in a wood, and I -
 /// I took the one less traveled by,
 /// And that has made all the difference.";
 ///
-/// let file = File::create("poem.txt")?;
-/// let mut file = LineWriter::new(file);
+///     let file = File::create("poem.txt")?;
+///     let mut file = LineWriter::new(file);
 ///
-/// for &byte in road_not_taken.iter() {
-///    file.write(&[byte]).unwrap();
-/// }
+///     for &byte in road_not_taken.iter() {
+///        file.write(&[byte]).unwrap();
+///     }
 ///
-/// // let's check we did the right thing.
-/// let mut file = File::open("poem.txt")?;
-/// let mut contents = String::new();
+///     // let's check we did the right thing.
+///     let mut file = File::open("poem.txt")?;
+///     let mut contents = String::new();
 ///
-/// file.read_to_string(&mut contents)?;
+///     file.read_to_string(&mut contents)?;
 ///
-/// assert_eq!(contents.as_bytes(), &road_not_taken[..]);
-/// # Ok(())
-/// # }
+///     assert_eq!(contents.as_bytes(), &road_not_taken[..]);
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct LineWriter<W: Write> {
@@ -736,15 +777,15 @@ impl<W: Write> LineWriter<W> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::fs::File;
     /// use std::io::LineWriter;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let file = File::create("poem.txt")?;
-    /// let file = LineWriter::new(file);
-    /// # Ok(())
-    /// # }
+    /// fn main() -> std::io::Result<()> {
+    ///     let file = File::create("poem.txt")?;
+    ///     let file = LineWriter::new(file);
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(inner: W) -> LineWriter<W> {
@@ -757,15 +798,15 @@ impl<W: Write> LineWriter<W> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::fs::File;
     /// use std::io::LineWriter;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let file = File::create("poem.txt")?;
-    /// let file = LineWriter::with_capacity(100, file);
-    /// # Ok(())
-    /// # }
+    /// fn main() -> std::io::Result<()> {
+    ///     let file = File::create("poem.txt")?;
+    ///     let file = LineWriter::with_capacity(100, file);
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(cap: usize, inner: W) -> LineWriter<W> {
@@ -779,17 +820,17 @@ impl<W: Write> LineWriter<W> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::fs::File;
     /// use std::io::LineWriter;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let file = File::create("poem.txt")?;
-    /// let file = LineWriter::new(file);
+    /// fn main() -> std::io::Result<()> {
+    ///     let file = File::create("poem.txt")?;
+    ///     let file = LineWriter::new(file);
     ///
-    /// let reference = file.get_ref();
-    /// # Ok(())
-    /// # }
+    ///     let reference = file.get_ref();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_ref(&self) -> &W { self.inner.get_ref() }
@@ -801,18 +842,18 @@ impl<W: Write> LineWriter<W> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::fs::File;
     /// use std::io::LineWriter;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let file = File::create("poem.txt")?;
-    /// let mut file = LineWriter::new(file);
+    /// fn main() -> std::io::Result<()> {
+    ///     let file = File::create("poem.txt")?;
+    ///     let mut file = LineWriter::new(file);
     ///
-    /// // we can use reference just like file
-    /// let reference = file.get_mut();
-    /// # Ok(())
-    /// # }
+    ///     // we can use reference just like file
+    ///     let reference = file.get_mut();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut W { self.inner.get_mut() }
@@ -827,18 +868,18 @@ impl<W: Write> LineWriter<W> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::fs::File;
     /// use std::io::LineWriter;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let file = File::create("poem.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let file = File::create("poem.txt")?;
     ///
-    /// let writer: LineWriter<File> = LineWriter::new(file);
+    ///     let writer: LineWriter<File> = LineWriter::new(file);
     ///
-    /// let file: File = writer.into_inner()?;
-    /// # Ok(())
-    /// # }
+    ///     let file: File = writer.into_inner()?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_inner(self) -> Result<W, IntoInnerError<LineWriter<W>>> {
diff --git a/ctr-std/src/io/cursor.rs b/ctr-std/src/io/cursor.rs
index 76bcb5f..2673f3c 100644
--- a/ctr-std/src/io/cursor.rs
+++ b/ctr-std/src/io/cursor.rs
@@ -10,7 +10,6 @@
 
 use io::prelude::*;
 
-use core::convert::TryInto;
 use cmp;
 use io::{self, Initializer, SeekFrom, Error, ErrorKind};
 
@@ -260,9 +259,26 @@ fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<us
     Ok(amt)
 }
 
+/// Compensate removal of some impls per
+/// https://github.com/rust-lang/rust/pull/49305#issuecomment-376293243
+#[cfg(any(target_pointer_width = "16",
+          target_pointer_width = "32"))]
+fn try_into(n: u64) -> Result<usize, ()> {
+    if n <= (<usize>::max_value() as u64) {
+        Ok(n as usize)
+    } else {
+        Err(())
+    }
+}
+
+#[cfg(any(target_pointer_width = "64"))]
+fn try_into(n: u64) -> Result<usize, ()> {
+    Ok(n as usize)
+}
+
 // Resizing write implementation
 fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
-    let pos: usize = (*pos_mut).try_into().map_err(|_| {
+    let pos: usize = try_into(*pos_mut).map_err(|_| {
         Error::new(ErrorKind::InvalidInput,
                     "cursor position exceeds maximum possible vector length")
     })?;
diff --git a/ctr-std/src/io/error.rs b/ctr-std/src/io/error.rs
index f0b41f3..bdd675e 100644
--- a/ctr-std/src/io/error.rs
+++ b/ctr-std/src/io/error.rs
@@ -292,8 +292,8 @@ impl Error {
     /// # if cfg!(target_os = "linux") {
     /// use std::io;
     ///
-    /// let error = io::Error::from_raw_os_error(98);
-    /// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
+    /// let error = io::Error::from_raw_os_error(22);
+    /// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
     /// # }
     /// ```
     ///
@@ -303,8 +303,8 @@ impl Error {
     /// # if cfg!(windows) {
     /// use std::io;
     ///
-    /// let error = io::Error::from_raw_os_error(10048);
-    /// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
+    /// let error = io::Error::from_raw_os_error(10022);
+    /// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
     /// # }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/ctr-std/src/io/mod.rs b/ctr-std/src/io/mod.rs
index 33d11eb..b02e133 100644
--- a/ctr-std/src/io/mod.rs
+++ b/ctr-std/src/io/mod.rs
@@ -24,21 +24,21 @@
 //! example, [`Read`] adds a [`read`][`Read::read`] method, which we can use on
 //! [`File`]s:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //! use std::io::prelude::*;
 //! use std::fs::File;
 //!
-//! # fn foo() -> io::Result<()> {
-//! let mut f = File::open("foo.txt")?;
-//! let mut buffer = [0; 10];
+//! fn main() -> io::Result<()> {
+//!     let mut f = File::open("foo.txt")?;
+//!     let mut buffer = [0; 10];
 //!
-//! // read up to 10 bytes
-//! f.read(&mut buffer)?;
+//!     // read up to 10 bytes
+//!     f.read(&mut buffer)?;
 //!
-//! println!("The bytes: {:?}", buffer);
-//! # Ok(())
-//! # }
+//!     println!("The bytes: {:?}", buffer);
+//!     Ok(())
+//! }
 //! ```
 //!
 //! [`Read`] and [`Write`] are so important, implementors of the two traits have a
@@ -52,25 +52,25 @@
 //! how the reading happens. [`Seek`] lets you control where the next byte is
 //! coming from:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //! use std::io::prelude::*;
 //! use std::io::SeekFrom;
 //! use std::fs::File;
 //!
-//! # fn foo() -> io::Result<()> {
-//! let mut f = File::open("foo.txt")?;
-//! let mut buffer = [0; 10];
+//! fn main() -> io::Result<()> {
+//!     let mut f = File::open("foo.txt")?;
+//!     let mut buffer = [0; 10];
 //!
-//! // skip to the last 10 bytes of the file
-//! f.seek(SeekFrom::End(-10))?;
+//!     // skip to the last 10 bytes of the file
+//!     f.seek(SeekFrom::End(-10))?;
 //!
-//! // read up to 10 bytes
-//! f.read(&mut buffer)?;
+//!     // read up to 10 bytes
+//!     f.read(&mut buffer)?;
 //!
-//! println!("The bytes: {:?}", buffer);
-//! # Ok(())
-//! # }
+//!     println!("The bytes: {:?}", buffer);
+//!     Ok(())
+//! }
 //! ```
 //!
 //! [`BufRead`] uses an internal buffer to provide a number of other ways to read, but
@@ -87,70 +87,70 @@
 //! For example, [`BufReader`] works with the [`BufRead`] trait to add extra
 //! methods to any reader:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //! use std::io::prelude::*;
 //! use std::io::BufReader;
 //! use std::fs::File;
 //!
-//! # fn foo() -> io::Result<()> {
-//! let f = File::open("foo.txt")?;
-//! let mut reader = BufReader::new(f);
-//! let mut buffer = String::new();
+//! fn main() -> io::Result<()> {
+//!     let f = File::open("foo.txt")?;
+//!     let mut reader = BufReader::new(f);
+//!     let mut buffer = String::new();
 //!
-//! // read a line into buffer
-//! reader.read_line(&mut buffer)?;
+//!     // read a line into buffer
+//!     reader.read_line(&mut buffer)?;
 //!
-//! println!("{}", buffer);
-//! # Ok(())
-//! # }
+//!     println!("{}", buffer);
+//!     Ok(())
+//! }
 //! ```
 //!
 //! [`BufWriter`] doesn't add any new ways of writing; it just buffers every call
 //! to [`write`][`Write::write`]:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //! use std::io::prelude::*;
 //! use std::io::BufWriter;
 //! use std::fs::File;
 //!
-//! # fn foo() -> io::Result<()> {
-//! let f = File::create("foo.txt")?;
-//! {
-//!     let mut writer = BufWriter::new(f);
+//! fn main() -> io::Result<()> {
+//!     let f = File::create("foo.txt")?;
+//!     {
+//!         let mut writer = BufWriter::new(f);
 //!
-//!     // write a byte to the buffer
-//!     writer.write(&[42])?;
+//!         // write a byte to the buffer
+//!         writer.write(&[42])?;
 //!
-//! } // the buffer is flushed once writer goes out of scope
+//!     } // the buffer is flushed once writer goes out of scope
 //!
-//! # Ok(())
-//! # }
+//!     Ok(())
+//! }
 //! ```
 //!
 //! ## Standard input and output
 //!
 //! A very common source of input is standard input:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //!
-//! # fn foo() -> io::Result<()> {
-//! let mut input = String::new();
+//! fn main() -> io::Result<()> {
+//!     let mut input = String::new();
 //!
-//! io::stdin().read_line(&mut input)?;
+//!     io::stdin().read_line(&mut input)?;
 //!
-//! println!("You typed: {}", input.trim());
-//! # Ok(())
-//! # }
+//!     println!("You typed: {}", input.trim());
+//!     Ok(())
+//! }
 //! ```
 //!
 //! Note that you cannot use the [`?` operator] in functions that do not return
 //! a [`Result<T, E>`][`Result`] (e.g. `main`). Instead, you can call [`.unwrap()`]
 //! or `match` on the return value to catch any possible errors:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //!
 //! let mut input = String::new();
@@ -160,14 +160,14 @@
 //!
 //! And a very common source of output is standard output:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //! use std::io::prelude::*;
 //!
-//! # fn foo() -> io::Result<()> {
-//! io::stdout().write(&[42])?;
-//! # Ok(())
-//! # }
+//! fn main() -> io::Result<()> {
+//!     io::stdout().write(&[42])?;
+//!     Ok(())
+//! }
 //! ```
 //!
 //! Of course, using [`io::stdout`] directly is less common than something like
@@ -179,22 +179,21 @@
 //! ways of iterating over I/O. For example, [`Lines`] is used to split over
 //! lines:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //! use std::io::prelude::*;
 //! use std::io::BufReader;
 //! use std::fs::File;
 //!
-//! # fn foo() -> io::Result<()> {
-//! let f = File::open("foo.txt")?;
-//! let reader = BufReader::new(f);
+//! fn main() -> io::Result<()> {
+//!     let f = File::open("foo.txt")?;
+//!     let reader = BufReader::new(f);
 //!
-//! for line in reader.lines() {
-//!     println!("{}", line?);
+//!     for line in reader.lines() {
+//!         println!("{}", line?);
+//!     }
+//!     Ok(())
 //! }
-//!
-//! # Ok(())
-//! # }
 //! ```
 //!
 //! ## Functions
@@ -203,13 +202,13 @@
 //! features. For example, we can use three of these functions to copy everything
 //! from standard input to standard output:
 //!
-//! ```
+//! ```no_run
 //! use std::io;
 //!
-//! # fn foo() -> io::Result<()> {
-//! io::copy(&mut io::stdin(), &mut io::stdout())?;
-//! # Ok(())
-//! # }
+//! fn main() -> io::Result<()> {
+//!     io::copy(&mut io::stdin(), &mut io::stdout())?;
+//!     Ok(())
+//! }
 //! ```
 //!
 //! [functions-list]: #functions-1
@@ -416,47 +415,47 @@ fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize>
 ///
 /// [`File`]s implement `Read`:
 ///
-/// ```
-/// # use std::io;
+/// ```no_run
+/// use std::io;
 /// use std::io::prelude::*;
 /// use std::fs::File;
 ///
-/// # fn foo() -> io::Result<()> {
-/// let mut f = File::open("foo.txt")?;
-/// let mut buffer = [0; 10];
+/// fn main() -> io::Result<()> {
+///     let mut f = File::open("foo.txt")?;
+///     let mut buffer = [0; 10];
 ///
-/// // read up to 10 bytes
-/// f.read(&mut buffer)?;
+///     // read up to 10 bytes
+///     f.read(&mut buffer)?;
 ///
-/// let mut buffer = vec![0; 10];
-/// // read the whole file
-/// f.read_to_end(&mut buffer)?;
+///     let mut buffer = vec![0; 10];
+///     // read the whole file
+///     f.read_to_end(&mut buffer)?;
 ///
-/// // read into a String, so that you don't need to do the conversion.
-/// let mut buffer = String::new();
-/// f.read_to_string(&mut buffer)?;
+///     // read into a String, so that you don't need to do the conversion.
+///     let mut buffer = String::new();
+///     f.read_to_string(&mut buffer)?;
 ///
-/// // and more! See the other methods for more details.
-/// # Ok(())
-/// # }
+///     // and more! See the other methods for more details.
+///     Ok(())
+/// }
 /// ```
 ///
 /// Read from [`&str`] because [`&[u8]`][slice] implements `Read`:
 ///
-/// ```
+/// ```no_run
 /// # use std::io;
 /// use std::io::prelude::*;
 ///
-/// # fn foo() -> io::Result<()> {
-/// let mut b = "This string will be read".as_bytes();
-/// let mut buffer = [0; 10];
+/// fn main() -> io::Result<()> {
+///     let mut b = "This string will be read".as_bytes();
+///     let mut buffer = [0; 10];
 ///
-/// // read up to 10 bytes
-/// b.read(&mut buffer)?;
+///     // read up to 10 bytes
+///     b.read(&mut buffer)?;
 ///
-/// // etc... it works exactly as a File does!
-/// # Ok(())
-/// # }
+///     // etc... it works exactly as a File does!
+///     Ok(())
+/// }
 /// ```
 ///
 /// [`read()`]: trait.Read.html#tymethod.read
@@ -509,19 +508,19 @@ pub trait Read {
     /// [`ErrorKind::Interrupted`]: ../../std/io/enum.ErrorKind.html#variant.Interrupted
     /// [`File`]: ../fs/struct.File.html
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
-    /// let mut buffer = [0; 10];
+    /// fn main() -> io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
+    ///     let mut buffer = [0; 10];
     ///
-    /// // read up to 10 bytes
-    /// f.read(&mut buffer[..])?;
-    /// # Ok(())
-    /// # }
+    ///     // read up to 10 bytes
+    ///     f.read(&mut buffer[..])?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn read(&mut self, buf: &mut [u8]) -> Result<usize>;
@@ -582,20 +581,25 @@ pub trait Read {
     /// [`ErrorKind::Interrupted`]: ../../std/io/enum.ErrorKind.html#variant.Interrupted
     /// [`File`]: ../fs/struct.File.html
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
-    /// let mut buffer = Vec::new();
+    /// fn main() -> io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
+    ///     let mut buffer = Vec::new();
     ///
-    /// // read the whole file
-    /// f.read_to_end(&mut buffer)?;
-    /// # Ok(())
-    /// # }
+    ///     // read the whole file
+    ///     f.read_to_end(&mut buffer)?;
+    ///     Ok(())
+    /// }
     /// ```
+    ///
+    /// (See also the [`std::fs::read`] convenience function for reading from a
+    /// file.)
+    ///
+    /// [`std::fs::read`]: ../fs/fn.read.html
     #[stable(feature = "rust1", since = "1.0.0")]
     fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize> {
         read_to_end(self, buf)
@@ -621,19 +625,24 @@ pub trait Read {
     ///
     /// [file]: ../fs/struct.File.html
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
-    /// let mut buffer = String::new();
+    /// fn main() -> io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
+    ///     let mut buffer = String::new();
     ///
-    /// f.read_to_string(&mut buffer)?;
-    /// # Ok(())
-    /// # }
+    ///     f.read_to_string(&mut buffer)?;
+    ///     Ok(())
+    /// }
     /// ```
+    ///
+    /// (See also the [`std::fs::read_to_string`] convenience function for
+    /// reading from a file.)
+    ///
+    /// [`std::fs::read_to_string`]: ../fs/fn.read_to_string.html
     #[stable(feature = "rust1", since = "1.0.0")]
     fn read_to_string(&mut self, buf: &mut String) -> Result<usize> {
         // Note that we do *not* call `.read_to_end()` here. We are passing
@@ -683,19 +692,19 @@ pub trait Read {
     /// [`ErrorKind::Interrupted`]: ../../std/io/enum.ErrorKind.html#variant.Interrupted
     /// [`ErrorKind::UnexpectedEof`]: ../../std/io/enum.ErrorKind.html#variant.UnexpectedEof
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
-    /// let mut buffer = [0; 10];
+    /// fn main() -> io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
+    ///     let mut buffer = [0; 10];
     ///
-    /// // read exactly 10 bytes
-    /// f.read_exact(&mut buffer)?;
-    /// # Ok(())
-    /// # }
+    ///     // read exactly 10 bytes
+    ///     f.read_exact(&mut buffer)?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "read_exact", since = "1.6.0")]
     fn read_exact(&mut self, mut buf: &mut [u8]) -> Result<()> {
@@ -726,28 +735,28 @@ pub trait Read {
     ///
     /// [file]: ../fs/struct.File.html
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::Read;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
-    /// let mut buffer = Vec::new();
-    /// let mut other_buffer = Vec::new();
+    /// fn main() -> io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
+    ///     let mut buffer = Vec::new();
+    ///     let mut other_buffer = Vec::new();
     ///
-    /// {
-    ///     let reference = f.by_ref();
+    ///     {
+    ///         let reference = f.by_ref();
     ///
-    ///     // read at most 5 bytes
-    ///     reference.take(5).read_to_end(&mut buffer)?;
+    ///         // read at most 5 bytes
+    ///         reference.take(5).read_to_end(&mut buffer)?;
     ///
-    /// } // drop our &mut reference so we can use f again
+    ///     } // drop our &mut reference so we can use f again
     ///
-    /// // original file still usable, read the rest
-    /// f.read_to_end(&mut other_buffer)?;
-    /// # Ok(())
-    /// # }
+    ///     // original file still usable, read the rest
+    ///     f.read_to_end(&mut other_buffer)?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn by_ref(&mut self) -> &mut Self where Self: Sized { self }
@@ -772,19 +781,19 @@ pub trait Read {
     /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
     ///
-    /// for byte in f.bytes() {
-    ///     println!("{}", byte.unwrap());
+    ///     for byte in f.bytes() {
+    ///         println!("{}", byte.unwrap());
+    ///     }
+    ///     Ok(())
     /// }
-    /// # Ok(())
-    /// # }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn bytes(self) -> Bytes<Self> where Self: Sized {
@@ -812,20 +821,20 @@ pub trait Read {
     /// [`char`]: ../../std/primitive.char.html
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
     ///
-    /// ```
+    /// ```no_run
     /// #![feature(io)]
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
     ///
-    /// for c in f.chars() {
-    ///     println!("{}", c.unwrap());
+    ///     for c in f.chars() {
+    ///         println!("{}", c.unwrap());
+    ///     }
+    ///     Ok(())
     /// }
-    /// # Ok(())
-    /// # }
     /// ```
     #[unstable(feature = "io", reason = "the semantics of a partial read/write \
                                          of where errors happen is currently \
@@ -847,23 +856,23 @@ pub trait Read {
     ///
     /// [file]: ../fs/struct.File.html
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f1 = File::open("foo.txt")?;
-    /// let mut f2 = File::open("bar.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut f1 = File::open("foo.txt")?;
+    ///     let mut f2 = File::open("bar.txt")?;
     ///
-    /// let mut handle = f1.chain(f2);
-    /// let mut buffer = String::new();
+    ///     let mut handle = f1.chain(f2);
+    ///     let mut buffer = String::new();
     ///
-    /// // read the value into a String. We could use any Read method here,
-    /// // this is just one example.
-    /// handle.read_to_string(&mut buffer)?;
-    /// # Ok(())
-    /// # }
+    ///     // read the value into a String. We could use any Read method here,
+    ///     // this is just one example.
+    ///     handle.read_to_string(&mut buffer)?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn chain<R: Read>(self, next: R) -> Chain<Self, R> where Self: Sized {
@@ -885,21 +894,21 @@ pub trait Read {
     /// [`Ok(0)`]: ../../std/result/enum.Result.html#variant.Ok
     /// [`read()`]: trait.Read.html#tymethod.read
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut f = File::open("foo.txt")?;
-    /// let mut buffer = [0; 5];
+    /// fn main() -> io::Result<()> {
+    ///     let mut f = File::open("foo.txt")?;
+    ///     let mut buffer = [0; 5];
     ///
-    /// // read at most five bytes
-    /// let mut handle = f.take(5);
+    ///     // read at most five bytes
+    ///     let mut handle = f.take(5);
     ///
-    /// handle.read(&mut buffer)?;
-    /// # Ok(())
-    /// # }
+    ///     handle.read(&mut buffer)?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn take(self, limit: u64) -> Take<Self> where Self: Sized {
@@ -974,16 +983,16 @@ impl Initializer {
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// use std::io::prelude::*;
 /// use std::fs::File;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// let mut buffer = File::create("foo.txt")?;
+/// fn main() -> std::io::Result<()> {
+///     let mut buffer = File::create("foo.txt")?;
 ///
-/// buffer.write(b"some bytes")?;
-/// # Ok(())
-/// # }
+///     buffer.write(b"some bytes")?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(spotlight)]
@@ -1022,17 +1031,17 @@ pub trait Write {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut buffer = File::create("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut buffer = File::create("foo.txt")?;
     ///
-    /// // Writes some prefix of the byte string, not necessarily all of it.
-    /// buffer.write(b"some bytes")?;
-    /// # Ok(())
-    /// # }
+    ///     // Writes some prefix of the byte string, not necessarily all of it.
+    ///     buffer.write(b"some bytes")?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn write(&mut self, buf: &[u8]) -> Result<usize>;
@@ -1047,18 +1056,18 @@ pub trait Write {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::prelude::*;
     /// use std::io::BufWriter;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut buffer = BufWriter::new(File::create("foo.txt")?);
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut buffer = BufWriter::new(File::create("foo.txt")?);
     ///
-    /// buffer.write(b"some bytes")?;
-    /// buffer.flush()?;
-    /// # Ok(())
-    /// # }
+    ///     buffer.write(b"some bytes")?;
+    ///     buffer.flush()?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn flush(&mut self) -> Result<()>;
@@ -1082,16 +1091,16 @@ pub trait Write {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut buffer = File::create("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut buffer = File::create("foo.txt")?;
     ///
-    /// buffer.write_all(b"some bytes")?;
-    /// # Ok(())
-    /// # }
+    ///     buffer.write_all(b"some bytes")?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn write_all(&mut self, mut buf: &[u8]) -> Result<()> {
@@ -1131,19 +1140,19 @@ pub trait Write {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut buffer = File::create("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut buffer = File::create("foo.txt")?;
     ///
-    /// // this call
-    /// write!(buffer, "{:.*}", 2, 1.234567)?;
-    /// // turns into this:
-    /// buffer.write_fmt(format_args!("{:.*}", 2, 1.234567))?;
-    /// # Ok(())
-    /// # }
+    ///     // this call
+    ///     write!(buffer, "{:.*}", 2, 1.234567)?;
+    ///     // turns into this:
+    ///     buffer.write_fmt(format_args!("{:.*}", 2, 1.234567))?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn write_fmt(&mut self, fmt: fmt::Arguments) -> Result<()> {
@@ -1187,19 +1196,19 @@ pub trait Write {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::Write;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> std::io::Result<()> {
-    /// let mut buffer = File::create("foo.txt")?;
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut buffer = File::create("foo.txt")?;
     ///
-    /// let reference = buffer.by_ref();
+    ///     let reference = buffer.by_ref();
     ///
-    /// // we can use reference just like our original buffer
-    /// reference.write_all(b"some bytes")?;
-    /// # Ok(())
-    /// # }
+    ///     // we can use reference just like our original buffer
+    ///     reference.write_all(b"some bytes")?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn by_ref(&mut self) -> &mut Self where Self: Sized { self }
@@ -1217,19 +1226,19 @@ pub trait Write {
 ///
 /// [file]: ../fs/struct.File.html
 ///
-/// ```
+/// ```no_run
 /// use std::io;
 /// use std::io::prelude::*;
 /// use std::fs::File;
 /// use std::io::SeekFrom;
 ///
-/// # fn foo() -> io::Result<()> {
-/// let mut f = File::open("foo.txt")?;
+/// fn main() -> io::Result<()> {
+///     let mut f = File::open("foo.txt")?;
 ///
-/// // move the cursor 42 bytes from the start of the file
-/// f.seek(SeekFrom::Start(42))?;
-/// # Ok(())
-/// # }
+///     // move the cursor 42 bytes from the start of the file
+///     f.seek(SeekFrom::Start(42))?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Seek {
@@ -1320,7 +1329,7 @@ fn read_until<R: BufRead + ?Sized>(r: &mut R, delim: u8, buf: &mut Vec<u8>)
 ///
 /// A locked standard input implements `BufRead`:
 ///
-/// ```
+/// ```no_run
 /// use std::io;
 /// use std::io::prelude::*;
 ///
@@ -1342,21 +1351,21 @@ fn read_until<R: BufRead + ?Sized>(r: &mut R, delim: u8, buf: &mut Vec<u8>)
 /// [`lines`]: #method.lines
 /// [`Read`]: trait.Read.html
 ///
-/// ```
+/// ```no_run
 /// use std::io::{self, BufReader};
 /// use std::io::prelude::*;
 /// use std::fs::File;
 ///
-/// # fn foo() -> io::Result<()> {
-/// let f = File::open("foo.txt")?;
-/// let f = BufReader::new(f);
+/// fn main() -> io::Result<()> {
+///     let f = File::open("foo.txt")?;
+///     let f = BufReader::new(f);
 ///
-/// for line in f.lines() {
-///     println!("{}", line.unwrap());
-/// }
+///     for line in f.lines() {
+///         println!("{}", line.unwrap());
+///     }
 ///
-/// # Ok(())
-/// # }
+///     Ok(())
+/// }
 /// ```
 ///
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1383,7 +1392,7 @@ pub trait BufRead: Read {
     ///
     /// A locked standard input implements `BufRead`:
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     ///
@@ -1437,8 +1446,6 @@ pub trait BufRead: Read {
     ///
     /// If successful, this function will return the total number of bytes read.
     ///
-    /// An empty buffer returned indicates that the stream has reached EOF.
-    ///
     /// # Errors
     ///
     /// This function will ignore all instances of [`ErrorKind::Interrupted`] and
@@ -1508,6 +1515,8 @@ pub trait BufRead: Read {
     /// error is encountered then `buf` may contain some bytes already read in
     /// the event that all data read so far was valid UTF-8.
     ///
+    /// [`read_until`]: #method.read_until
+    ///
     /// # Examples
     ///
     /// [`std::io::Cursor`][`Cursor`] is a type that implements `BufRead`. In
@@ -1645,19 +1654,19 @@ impl<T, U> Chain<T, U> {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # use std::io;
+    /// ```no_run
+    /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut foo_file = File::open("foo.txt")?;
-    /// let mut bar_file = File::open("bar.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut foo_file = File::open("foo.txt")?;
+    ///     let mut bar_file = File::open("bar.txt")?;
     ///
-    /// let chain = foo_file.chain(bar_file);
-    /// let (foo_file, bar_file) = chain.into_inner();
-    /// # Ok(())
-    /// # }
+    ///     let chain = foo_file.chain(bar_file);
+    ///     let (foo_file, bar_file) = chain.into_inner();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "more_io_inner_methods", since = "1.20.0")]
     pub fn into_inner(self) -> (T, U) {
@@ -1668,19 +1677,19 @@ impl<T, U> Chain<T, U> {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # use std::io;
+    /// ```no_run
+    /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut foo_file = File::open("foo.txt")?;
-    /// let mut bar_file = File::open("bar.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut foo_file = File::open("foo.txt")?;
+    ///     let mut bar_file = File::open("bar.txt")?;
     ///
-    /// let chain = foo_file.chain(bar_file);
-    /// let (foo_file, bar_file) = chain.get_ref();
-    /// # Ok(())
-    /// # }
+    ///     let chain = foo_file.chain(bar_file);
+    ///     let (foo_file, bar_file) = chain.get_ref();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "more_io_inner_methods", since = "1.20.0")]
     pub fn get_ref(&self) -> (&T, &U) {
@@ -1695,19 +1704,19 @@ impl<T, U> Chain<T, U> {
     ///
     /// # Examples
     ///
-    /// ```
-    /// # use std::io;
+    /// ```no_run
+    /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut foo_file = File::open("foo.txt")?;
-    /// let mut bar_file = File::open("bar.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut foo_file = File::open("foo.txt")?;
+    ///     let mut bar_file = File::open("bar.txt")?;
     ///
-    /// let mut chain = foo_file.chain(bar_file);
-    /// let (foo_file, bar_file) = chain.get_mut();
-    /// # Ok(())
-    /// # }
+    ///     let mut chain = foo_file.chain(bar_file);
+    ///     let (foo_file, bar_file) = chain.get_mut();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "more_io_inner_methods", since = "1.20.0")]
     pub fn get_mut(&mut self) -> (&mut T, &mut U) {
@@ -1794,20 +1803,20 @@ impl<T> Take<T> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let f = File::open("foo.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let f = File::open("foo.txt")?;
     ///
-    /// // read at most five bytes
-    /// let handle = f.take(5);
+    ///     // read at most five bytes
+    ///     let handle = f.take(5);
     ///
-    /// println!("limit: {}", handle.limit());
-    /// # Ok(())
-    /// # }
+    ///     println!("limit: {}", handle.limit());
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn limit(&self) -> u64 { self.limit }
@@ -1819,24 +1828,23 @@ impl<T> Take<T> {
     ///
     /// # Examples
     ///
-    /// ```
-    /// #![feature(take_set_limit)]
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let f = File::open("foo.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let f = File::open("foo.txt")?;
     ///
-    /// // read at most five bytes
-    /// let mut handle = f.take(5);
-    /// handle.set_limit(10);
+    ///     // read at most five bytes
+    ///     let mut handle = f.take(5);
+    ///     handle.set_limit(10);
     ///
-    /// assert_eq!(handle.limit(), 10);
-    /// # Ok(())
-    /// # }
+    ///     assert_eq!(handle.limit(), 10);
+    ///     Ok(())
+    /// }
     /// ```
-    #[unstable(feature = "take_set_limit", issue = "42781")]
+    #[stable(feature = "take_set_limit", since = "1.27.0")]
     pub fn set_limit(&mut self, limit: u64) {
         self.limit = limit;
     }
@@ -1845,21 +1853,21 @@ impl<T> Take<T> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut file = File::open("foo.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut file = File::open("foo.txt")?;
     ///
-    /// let mut buffer = [0; 5];
-    /// let mut handle = file.take(5);
-    /// handle.read(&mut buffer)?;
+    ///     let mut buffer = [0; 5];
+    ///     let mut handle = file.take(5);
+    ///     handle.read(&mut buffer)?;
     ///
-    /// let file = handle.into_inner();
-    /// # Ok(())
-    /// # }
+    ///     let file = handle.into_inner();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "io_take_into_inner", since = "1.15.0")]
     pub fn into_inner(self) -> T {
@@ -1870,21 +1878,21 @@ impl<T> Take<T> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut file = File::open("foo.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut file = File::open("foo.txt")?;
     ///
-    /// let mut buffer = [0; 5];
-    /// let mut handle = file.take(5);
-    /// handle.read(&mut buffer)?;
+    ///     let mut buffer = [0; 5];
+    ///     let mut handle = file.take(5);
+    ///     handle.read(&mut buffer)?;
     ///
-    /// let file = handle.get_ref();
-    /// # Ok(())
-    /// # }
+    ///     let file = handle.get_ref();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "more_io_inner_methods", since = "1.20.0")]
     pub fn get_ref(&self) -> &T {
@@ -1899,21 +1907,21 @@ impl<T> Take<T> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io;
     /// use std::io::prelude::*;
     /// use std::fs::File;
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let mut file = File::open("foo.txt")?;
+    /// fn main() -> io::Result<()> {
+    ///     let mut file = File::open("foo.txt")?;
     ///
-    /// let mut buffer = [0; 5];
-    /// let mut handle = file.take(5);
-    /// handle.read(&mut buffer)?;
+    ///     let mut buffer = [0; 5];
+    ///     let mut handle = file.take(5);
+    ///     handle.read(&mut buffer)?;
     ///
-    /// let file = handle.get_mut();
-    /// # Ok(())
-    /// # }
+    ///     let file = handle.get_mut();
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "more_io_inner_methods", since = "1.20.0")]
     pub fn get_mut(&mut self) -> &mut T {
diff --git a/ctr-std/src/io/stdio.rs b/ctr-std/src/io/stdio.rs
index 831688b..2472bed 100644
--- a/ctr-std/src/io/stdio.rs
+++ b/ctr-std/src/io/stdio.rs
@@ -17,7 +17,7 @@ use io::{self, Initializer, BufReader, LineWriter};
 use sync::{Arc, Mutex, MutexGuard};
 use sys::stdio;
 use sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard};
-use thread::{LocalKey, LocalKeyState};
+use thread::LocalKey;
 
 /// Stdout used by print! and println! macros
 thread_local! {
@@ -171,29 +171,29 @@ pub struct StdinLock<'a> {
 ///
 /// Using implicit synchronization:
 ///
-/// ```
+/// ```no_run
 /// use std::io::{self, Read};
 ///
-/// # fn foo() -> io::Result<String> {
-/// let mut buffer = String::new();
-/// io::stdin().read_to_string(&mut buffer)?;
-/// # Ok(buffer)
-/// # }
+/// fn main() -> io::Result<()> {
+///     let mut buffer = String::new();
+///     io::stdin().read_to_string(&mut buffer)?;
+///     Ok(())
+/// }
 /// ```
 ///
 /// Using explicit synchronization:
 ///
-/// ```
+/// ```no_run
 /// use std::io::{self, Read};
 ///
-/// # fn foo() -> io::Result<String> {
-/// let mut buffer = String::new();
-/// let stdin = io::stdin();
-/// let mut handle = stdin.lock();
+/// fn main() -> io::Result<()> {
+///     let mut buffer = String::new();
+///     let stdin = io::stdin();
+///     let mut handle = stdin.lock();
 ///
-/// handle.read_to_string(&mut buffer)?;
-/// # Ok(buffer)
-/// # }
+///     handle.read_to_string(&mut buffer)?;
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn stdin() -> Stdin {
@@ -225,17 +225,17 @@ impl Stdin {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::{self, Read};
     ///
-    /// # fn foo() -> io::Result<String> {
-    /// let mut buffer = String::new();
-    /// let stdin = io::stdin();
-    /// let mut handle = stdin.lock();
+    /// fn main() -> io::Result<()> {
+    ///     let mut buffer = String::new();
+    ///     let stdin = io::stdin();
+    ///     let mut handle = stdin.lock();
     ///
-    /// handle.read_to_string(&mut buffer)?;
-    /// # Ok(buffer)
-    /// # }
+    ///     handle.read_to_string(&mut buffer)?;
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn lock(&self) -> StdinLock {
@@ -369,29 +369,29 @@ pub struct StdoutLock<'a> {
 ///
 /// Using implicit synchronization:
 ///
-/// ```
+/// ```no_run
 /// use std::io::{self, Write};
 ///
-/// # fn foo() -> io::Result<()> {
-/// io::stdout().write(b"hello world")?;
+/// fn main() -> io::Result<()> {
+///     io::stdout().write(b"hello world")?;
 ///
-/// # Ok(())
-/// # }
+///     Ok(())
+/// }
 /// ```
 ///
 /// Using explicit synchronization:
 ///
-/// ```
+/// ```no_run
 /// use std::io::{self, Write};
 ///
-/// # fn foo() -> io::Result<()> {
-/// let stdout = io::stdout();
-/// let mut handle = stdout.lock();
+/// fn main() -> io::Result<()> {
+///     let stdout = io::stdout();
+///     let mut handle = stdout.lock();
 ///
-/// handle.write(b"hello world")?;
+///     handle.write(b"hello world")?;
 ///
-/// # Ok(())
-/// # }
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn stdout() -> Stdout {
@@ -419,17 +419,17 @@ impl Stdout {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// use std::io::{self, Write};
     ///
-    /// # fn foo() -> io::Result<()> {
-    /// let stdout = io::stdout();
-    /// let mut handle = stdout.lock();
+    /// fn main() -> io::Result<()> {
+    ///     let stdout = io::stdout();
+    ///     let mut handle = stdout.lock();
     ///
-    /// handle.write(b"hello world")?;
+    ///     handle.write(b"hello world")?;
     ///
-    /// # Ok(())
-    /// # }
+    ///     Ok(())
+    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn lock(&self) -> StdoutLock {
@@ -505,29 +505,29 @@ pub struct StderrLock<'a> {
 ///
 /// Using implicit synchronization:
 ///
-/// ```
+/// ```no_run
 /// use std::io::{self, Write};
 ///
-/// # fn foo() -> io::Result<()> {
-/// io::stderr().write(b"hello world")?;
+/// fn main() -> io::Result<()> {
+///     io::stderr().write(b"hello world")?;
 ///
-/// # Ok(())
-/// # }
+///     Ok(())
+/// }
 /// ```
 ///
 /// Using explicit synchronization:
 ///
-/// ```
+/// ```no_run
 /// use std::io::{self, Write};
 ///
-/// # fn foo() -> io::Result<()> {
-/// let stderr = io::stderr();
-/// let mut handle = stderr.lock();
+/// fn main() -> io::Result<()> {
+///     let stderr = io::stderr();
+///     let mut handle = stderr.lock();
 ///
-/// handle.write(b"hello world")?;
+///     handle.write(b"hello world")?;
 ///
-/// # Ok(())
-/// # }
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn stderr() -> Stderr {
@@ -663,29 +663,31 @@ pub fn set_print(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
 ///
 /// This function is used to print error messages, so it takes extra
 /// care to avoid causing a panic when `local_stream` is unusable.
-/// For instance, if the TLS key for the local stream is uninitialized
-/// or already destroyed, or if the local stream is locked by another
+/// For instance, if the TLS key for the local stream is
+/// already destroyed, or if the local stream is locked by another
 /// thread, it will just fall back to the global stream.
 ///
 /// However, if the actual I/O causes an error, this function does panic.
-fn print_to<T>(args: fmt::Arguments,
-               local_s: &'static LocalKey<RefCell<Option<Box<Write+Send>>>>,
-               global_s: fn() -> T,
-               label: &str) where T: Write {
-    let result = match local_s.state() {
-        LocalKeyState::Uninitialized |
-        LocalKeyState::Destroyed => global_s().write_fmt(args),
-        LocalKeyState::Valid => {
-            local_s.with(|s| {
-                if let Ok(mut borrowed) = s.try_borrow_mut() {
-                    if let Some(w) = borrowed.as_mut() {
-                        return w.write_fmt(args);
-                    }
-                }
-                global_s().write_fmt(args)
-            })
+fn print_to<T>(
+    args: fmt::Arguments,
+    local_s: &'static LocalKey<RefCell<Option<Box<Write+Send>>>>,
+    global_s: fn() -> T,
+    label: &str,
+)
+where
+    T: Write,
+{
+    let result = local_s.try_with(|s| {
+        if let Ok(mut borrowed) = s.try_borrow_mut() {
+            if let Some(w) = borrowed.as_mut() {
+                return w.write_fmt(args);
+            }
         }
-    };
+        global_s().write_fmt(args)
+    }).unwrap_or_else(|_| {
+        global_s().write_fmt(args)
+    });
+
     if let Err(e) = result {
         panic!("failed printing to {}: {}", label, e);
     }
diff --git a/ctr-std/src/io/util.rs b/ctr-std/src/io/util.rs
index 45d281e..195310a 100644
--- a/ctr-std/src/io/util.rs
+++ b/ctr-std/src/io/util.rs
@@ -34,16 +34,15 @@ use mem;
 /// ```
 /// use std::io;
 ///
-/// # fn foo() -> io::Result<()> {
-/// let mut reader: &[u8] = b"hello";
-/// let mut writer: Vec<u8> = vec![];
+/// fn main() -> io::Result<()> {
+///     let mut reader: &[u8] = b"hello";
+///     let mut writer: Vec<u8> = vec![];
 ///
-/// io::copy(&mut reader, &mut writer)?;
+///     io::copy(&mut reader, &mut writer)?;
 ///
-/// assert_eq!(&b"hello"[..], &writer[..]);
-/// # Ok(())
-/// # }
-/// # foo().unwrap();
+///     assert_eq!(&b"hello"[..], &writer[..]);
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
diff --git a/ctr-std/src/lib.rs b/ctr-std/src/lib.rs
index a0d76cf..146e23c 100644
--- a/ctr-std/src/lib.rs
+++ b/ctr-std/src/lib.rs
@@ -259,6 +259,7 @@
 #![feature(core_float)]
 #![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]
+#![feature(exhaustive_patterns)]
 #![feature(exact_size_is_empty)]
 #![feature(fs_read_write)]
 #![feature(fixed_size_array)]
@@ -266,11 +267,9 @@
 #![feature(fn_traits)]
 #![feature(fnbox)]
 #![feature(fused)]
-#![feature(generic_param_attrs)]
 #![feature(hashmap_hasher)]
+#![feature(hashmap_internals)]
 #![feature(heap_api)]
-#![feature(i128)]
-#![feature(i128_type)]
 #![feature(inclusive_range)]
 #![feature(int_error_internals)]
 #![feature(integer_atomics)]
@@ -283,6 +282,8 @@
 #![feature(macro_vis_matcher)]
 #![feature(needs_panic_runtime)]
 #![feature(never_type)]
+#![feature(nonnull_cast)]
+#![feature(nonzero)]
 #![feature(num_bits_bytes)]
 #![feature(old_wrapping)]
 #![feature(on_unimplemented)]
@@ -297,21 +298,23 @@
 #![feature(rand)]
 #![feature(raw)]
 #![feature(rustc_attrs)]
+#![feature(shrink_to)]
 #![feature(sip_hash_13)]
 #![feature(slice_bytes)]
 #![feature(slice_concat_ext)]
 #![feature(slice_internals)]
 #![feature(slice_patterns)]
 #![feature(staged_api)]
+#![feature(stdsimd)]
 #![feature(stmt_expr_attributes)]
 #![feature(str_char)]
 #![feature(str_internals)]
 #![feature(str_utf16)]
-#![feature(termination_trait)]
 #![feature(test, rustc_private)]
 #![feature(thread_local)]
 #![feature(toowned_clone_into)]
 #![feature(try_from)]
+#![feature(try_reserve)]
 #![feature(unboxed_closures)]
 #![feature(unicode)]
 #![feature(untagged_unions)]
@@ -352,15 +355,14 @@ use prelude::v1::*;
 // We want to re-export a few macros from core but libcore has already been
 // imported by the compiler (via our #[no_std] attribute) In this case we just
 // add a new crate name so we can attach the re-exports to it.
-#[macro_reexport(assert, assert_eq, assert_ne, debug_assert, debug_assert_eq,
+#[macro_reexport(assert_eq, assert_ne, debug_assert, debug_assert_eq,
                  debug_assert_ne, unreachable, unimplemented, write, writeln, try)]
 extern crate core as __core;
 
 #[macro_use]
 #[macro_reexport(vec, format)]
-extern crate alloc;
+extern crate alloc as alloc_crate;
 extern crate alloc_system;
-extern crate std_unicode;
 #[doc(masked)]
 extern crate libc;
 
@@ -372,10 +374,6 @@ extern crate ctru_sys as libctru;
 #[allow(unused_extern_crates)]
 extern crate unwind;
 
-// compiler-rt intrinsics
-#[doc(masked)]
-extern crate compiler_builtins;
-
 // During testing, this crate is not actually the "real" std library, but rather
 // it links to the real std library, which was compiled from this same source
 // code. So any lang items std defines are conditionally excluded (or else they
@@ -447,23 +445,23 @@ pub use core::u32;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::u64;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::boxed;
+pub use alloc_crate::boxed;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::rc;
+pub use alloc_crate::rc;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::borrow;
+pub use alloc_crate::borrow;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::fmt;
+pub use alloc_crate::fmt;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::slice;
+pub use alloc_crate::slice;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::str;
+pub use alloc_crate::str;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::string;
+pub use alloc_crate::string;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::vec;
+pub use alloc_crate::vec;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use std_unicode::char;
+pub use core::char;
 #[unstable(feature = "i128", issue = "35118")]
 pub use core::u128;
 
@@ -487,7 +485,14 @@ pub mod path;
 pub mod process;
 pub mod sync;
 pub mod time;
-pub mod heap;
+pub mod alloc;
+
+#[unstable(feature = "allocator_api", issue = "32838")]
+#[rustc_deprecated(since = "1.27.0", reason = "module renamed to `alloc`")]
+/// Use the `alloc` module instead.
+pub mod heap {
+    pub use alloc::*;
+}
 
 // Platform-abstraction modules
 #[macro_use]
@@ -501,11 +506,6 @@ mod memchr;
 // The runtime entry point and a few unstable public functions used by the
 // compiler
 pub mod rt;
-// The trait to support returning arbitrary types in the main function
-mod termination;
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-pub use self::termination::Termination;
 
 // Include a number of private modules that exist solely to provide
 // the rustdoc documentation for primitive types. Using `include!`
diff --git a/ctr-std/src/macros.rs b/ctr-std/src/macros.rs
index f058b1c..5ef7c15 100644
--- a/ctr-std/src/macros.rs
+++ b/ctr-std/src/macros.rs
@@ -68,6 +68,9 @@ macro_rules! panic {
     ($msg:expr) => ({
         $crate::rt::begin_panic($msg, &(file!(), line!(), __rust_unstable_column!()))
     });
+    ($msg:expr,) => ({
+        panic!($msg)
+    });
     ($fmt:expr, $($arg:tt)+) => ({
         $crate::rt::begin_panic_fmt(&format_args!($fmt, $($arg)+),
                                     &(file!(), line!(), __rust_unstable_column!()))
@@ -312,7 +315,10 @@ pub mod builtin {
     /// ```
     #[stable(feature = "compile_error_macro", since = "1.20.0")]
     #[macro_export]
-    macro_rules! compile_error { ($msg:expr) => ({ /* compiler built-in */ }) }
+    macro_rules! compile_error {
+        ($msg:expr) => ({ /* compiler built-in */ });
+        ($msg:expr,) => ({ /* compiler built-in */ });
+    }
 
     /// The core macro for formatted string creation & output.
     ///
@@ -329,6 +335,18 @@ pub mod builtin {
     /// proxied through this one.  `format_args!`, unlike its derived macros, avoids
     /// heap allocations.
     ///
+    /// You can use the [`fmt::Arguments`] value that `format_args!` returns
+    /// in `Debug` and `Display` contexts as seen below. The example also shows
+    /// that `Debug` and `Display` format to the same thing: the interpolated
+    /// format string in `format_args!`.
+    ///
+    /// ```rust
+    /// let debug = format!("{:?}", format_args!("{} foo {:?}", 1, 2));
+    /// let display = format!("{}", format_args!("{} foo {:?}", 1, 2));
+    /// assert_eq!("1 foo 2", display);
+    /// assert_eq!(display, debug);
+    /// ```
+    ///
     /// For more information, see the documentation in [`std::fmt`].
     ///
     /// [`Display`]: ../std/fmt/trait.Display.html
@@ -400,7 +418,10 @@ pub mod builtin {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[macro_export]
-    macro_rules! option_env { ($name:expr) => ({ /* compiler built-in */ }) }
+    macro_rules! option_env {
+        ($name:expr) => ({ /* compiler built-in */ });
+        ($name:expr,) => ({ /* compiler built-in */ });
+    }
 
     /// Concatenate identifiers into one identifier.
     ///
@@ -463,7 +484,7 @@ pub mod builtin {
     /// The expanded expression has type `u32` and is 1-based, so the first line
     /// in each file evaluates to 1, the second to 2, etc. This is consistent
     /// with error messages by common compilers or popular editors.
-    /// The returned line is not the invocation of the `line!` macro itself,
+    /// The returned line is *not necessarily* the line of the `line!` invocation itself,
     /// but rather the first macro invocation leading up to the invocation
     /// of the `line!` macro.
     ///
@@ -488,7 +509,7 @@ pub mod builtin {
     /// The expanded expression has type `u32` and is 1-based, so the first column
     /// in each line evaluates to 1, the second to 2, etc. This is consistent
     /// with error messages by common compilers or popular editors.
-    /// The returned column is not the invocation of the `column!` macro itself,
+    /// The returned column is *not necessarily* the line of the `column!` invocation itself,
     /// but rather the first macro invocation leading up to the invocation
     /// of the `column!` macro.
     ///
@@ -580,7 +601,10 @@ pub mod builtin {
     /// Compiling 'main.rs' and running the resulting binary will print "adiós".
     #[stable(feature = "rust1", since = "1.0.0")]
     #[macro_export]
-    macro_rules! include_str { ($file:expr) => ({ /* compiler built-in */ }) }
+    macro_rules! include_str {
+        ($file:expr) => ({ /* compiler built-in */ });
+        ($file:expr,) => ({ /* compiler built-in */ });
+    }
 
     /// Includes a file as a reference to a byte array.
     ///
@@ -614,7 +638,10 @@ pub mod builtin {
     /// Compiling 'main.rs' and running the resulting binary will print "adiós".
     #[stable(feature = "rust1", since = "1.0.0")]
     #[macro_export]
-    macro_rules! include_bytes { ($file:expr) => ({ /* compiler built-in */ }) }
+    macro_rules! include_bytes {
+        ($file:expr) => ({ /* compiler built-in */ });
+        ($file:expr,) => ({ /* compiler built-in */ });
+    }
 
     /// Expands to a string that represents the current module path.
     ///
@@ -700,7 +727,64 @@ pub mod builtin {
     /// "🙈🙊🙉🙈🙊🙉".
     #[stable(feature = "rust1", since = "1.0.0")]
     #[macro_export]
-    macro_rules! include { ($file:expr) => ({ /* compiler built-in */ }) }
+    macro_rules! include {
+        ($file:expr) => ({ /* compiler built-in */ });
+        ($file:expr,) => ({ /* compiler built-in */ });
+    }
+
+    /// Ensure that a boolean expression is `true` at runtime.
+    ///
+    /// This will invoke the [`panic!`] macro if the provided expression cannot be
+    /// evaluated to `true` at runtime.
+    ///
+    /// # Uses
+    ///
+    /// Assertions are always checked in both debug and release builds, and cannot
+    /// be disabled. See [`debug_assert!`] for assertions that are not enabled in
+    /// release builds by default.
+    ///
+    /// Unsafe code relies on `assert!` to enforce run-time invariants that, if
+    /// violated could lead to unsafety.
+    ///
+    /// Other use-cases of `assert!` include [testing] and enforcing run-time
+    /// invariants in safe code (whose violation cannot result in unsafety).
+    ///
+    /// # Custom Messages
+    ///
+    /// This macro has a second form, where a custom panic message can
+    /// be provided with or without arguments for formatting.  See [`std::fmt`]
+    /// for syntax for this form.
+    ///
+    /// [`panic!`]: macro.panic.html
+    /// [`debug_assert!`]: macro.debug_assert.html
+    /// [testing]: ../book/second-edition/ch11-01-writing-tests.html#checking-results-with-the-assert-macro
+    /// [`std::fmt`]: ../std/fmt/index.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// // the panic message for these assertions is the stringified value of the
+    /// // expression given.
+    /// assert!(true);
+    ///
+    /// fn some_computation() -> bool { true } // a very simple function
+    ///
+    /// assert!(some_computation());
+    ///
+    /// // assert with a custom message
+    /// let x = true;
+    /// assert!(x, "x wasn't true!");
+    ///
+    /// let a = 3; let b = 27;
+    /// assert!(a + b == 30, "a = {}, b = {}", a, b);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[macro_export]
+    macro_rules! assert {
+        ($cond:expr) => ({ /* compiler built-in */ });
+        ($cond:expr,) => ({ /* compiler built-in */ });
+        ($cond:expr, $($arg:tt)+) => ({ /* compiler built-in */ });
+    }
 }
 
 /// A macro for defining #[cfg] if-else statements.
diff --git a/ctr-std/src/net/addr.rs b/ctr-std/src/net/addr.rs
index 1ca7e66..bc2c9f5 100644
--- a/ctr-std/src/net/addr.rs
+++ b/ctr-std/src/net/addr.rs
@@ -12,7 +12,9 @@ use fmt;
 use hash;
 use io;
 use mem;
-use net::{lookup_host, ntoh, hton, IpAddr, Ipv4Addr, Ipv6Addr};
+use net::{ntoh, hton, IpAddr, Ipv4Addr, Ipv6Addr};
+#[allow(deprecated)]
+use net::lookup_host;
 use option;
 use sys::net::netc as c;
 use sys_common::{FromInner, AsInner, IntoInner};
@@ -26,6 +28,9 @@ use slice;
 /// as possibly some version-dependent additional information. See [`SocketAddrV4`]'s and
 /// [`SocketAddrV6`]'s respective documentation for more details.
 ///
+/// The size of a `SocketAddr` instance may vary depending on the target operating
+/// system.
+///
 /// [IP address]: ../../std/net/enum.IpAddr.html
 /// [`SocketAddrV4`]: ../../std/net/struct.SocketAddrV4.html
 /// [`SocketAddrV6`]: ../../std/net/struct.SocketAddrV6.html
@@ -59,6 +64,9 @@ pub enum SocketAddr {
 ///
 /// See [`SocketAddr`] for a type encompassing both IPv4 and IPv6 socket addresses.
 ///
+/// The size of a `SocketAddrV4` struct may vary depending on the target operating
+/// system.
+///
 /// [IETF RFC 793]: https://tools.ietf.org/html/rfc793
 /// [IPv4 address]: ../../std/net/struct.Ipv4Addr.html
 /// [`SocketAddr`]: ../../std/net/enum.SocketAddr.html
@@ -86,6 +94,9 @@ pub struct SocketAddrV4 { inner: c::sockaddr_in }
 ///
 /// See [`SocketAddr`] for a type encompassing both IPv4 and IPv6 socket addresses.
 ///
+/// The size of a `SocketAddrV6` struct may vary depending on the target operating
+/// system.
+///
 /// [IETF RFC 2553, Section 3.3]: https://tools.ietf.org/html/rfc2553#section-3.3
 /// [IPv6 address]: ../../std/net/struct.Ipv6Addr.html
 /// [`SocketAddr`]: ../../std/net/enum.SocketAddr.html
@@ -845,6 +856,7 @@ impl ToSocketAddrs for (Ipv6Addr, u16) {
     }
 }
 
+#[allow(deprecated)]
 fn resolve_socket_addr(s: &str, p: u16) -> io::Result<vec::IntoIter<SocketAddr>> {
     let ips = lookup_host(s)?;
     let v: Vec<_> = ips.map(|mut a| { a.set_port(p); a }).collect();
diff --git a/ctr-std/src/net/ip.rs b/ctr-std/src/net/ip.rs
index 0d73a6f..fcec8d0 100644
--- a/ctr-std/src/net/ip.rs
+++ b/ctr-std/src/net/ip.rs
@@ -26,6 +26,9 @@ use sys_common::{AsInner, FromInner};
 /// This enum can contain either an [`Ipv4Addr`] or an [`Ipv6Addr`], see their
 /// respective documentation for more details.
 ///
+/// The size of an `IpAddr` instance may vary depending on the target operating
+/// system.
+///
 /// [`Ipv4Addr`]: ../../std/net/struct.Ipv4Addr.html
 /// [`Ipv6Addr`]: ../../std/net/struct.Ipv6Addr.html
 ///
@@ -61,6 +64,9 @@ pub enum IpAddr {
 ///
 /// See [`IpAddr`] for a type encompassing both IPv4 and IPv6 addresses.
 ///
+/// The size of an `Ipv4Addr` struct may vary depending on the target operating
+/// system.
+///
 /// [IETF RFC 791]: https://tools.ietf.org/html/rfc791
 /// [`IpAddr`]: ../../std/net/enum.IpAddr.html
 ///
@@ -93,6 +99,9 @@ pub struct Ipv4Addr {
 ///
 /// See [`IpAddr`] for a type encompassing both IPv4 and IPv6 addresses.
 ///
+/// The size of an `Ipv6Addr` struct may vary depending on the target operating
+/// system.
+///
 /// [IETF RFC 4291]: https://tools.ietf.org/html/rfc4291
 /// [`IpAddr`]: ../../std/net/enum.IpAddr.html
 ///
@@ -769,7 +778,16 @@ impl FromInner<c::in_addr> for Ipv4Addr {
 
 #[stable(feature = "ip_u32", since = "1.1.0")]
 impl From<Ipv4Addr> for u32 {
-    /// It performs the conversion in network order (big-endian).
+    /// Convert an `Ipv4Addr` into a host byte order `u32`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::Ipv4Addr;
+    ///
+    /// let addr = Ipv4Addr::new(13, 12, 11, 10);
+    /// assert_eq!(0x0d0c0b0au32, u32::from(addr));
+    /// ```
     fn from(ip: Ipv4Addr) -> u32 {
         let ip = ip.octets();
         ((ip[0] as u32) << 24) + ((ip[1] as u32) << 16) + ((ip[2] as u32) << 8) + (ip[3] as u32)
@@ -778,7 +796,16 @@ impl From<Ipv4Addr> for u32 {
 
 #[stable(feature = "ip_u32", since = "1.1.0")]
 impl From<u32> for Ipv4Addr {
-    /// It performs the conversion in network order (big-endian).
+    /// Convert a host byte order `u32` into an `Ipv4Addr`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::Ipv4Addr;
+    ///
+    /// let addr = Ipv4Addr::from(0x0d0c0b0au32);
+    /// assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
+    /// ```
     fn from(ip: u32) -> Ipv4Addr {
         Ipv4Addr::new((ip >> 24) as u8, (ip >> 16) as u8, (ip >> 8) as u8, ip as u8)
     }
@@ -786,6 +813,14 @@ impl From<u32> for Ipv4Addr {
 
 #[stable(feature = "from_slice_v4", since = "1.9.0")]
 impl From<[u8; 4]> for Ipv4Addr {
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::Ipv4Addr;
+    ///
+    /// let addr = Ipv4Addr::from([13u8, 12u8, 11u8, 10u8]);
+    /// assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
+    /// ```
     fn from(octets: [u8; 4]) -> Ipv4Addr {
         Ipv4Addr::new(octets[0], octets[1], octets[2], octets[3])
     }
@@ -793,6 +828,16 @@ impl From<[u8; 4]> for Ipv4Addr {
 
 #[stable(feature = "ip_from_slice", since = "1.17.0")]
 impl From<[u8; 4]> for IpAddr {
+    /// Create an `IpAddr::V4` from a four element byte array.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::{IpAddr, Ipv4Addr};
+    ///
+    /// let addr = IpAddr::from([13u8, 12u8, 11u8, 10u8]);
+    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(13, 12, 11, 10)), addr);
+    /// ```
     fn from(octets: [u8; 4]) -> IpAddr {
         IpAddr::V4(Ipv4Addr::from(octets))
     }
@@ -1346,7 +1391,7 @@ impl FromInner<c::in6_addr> for Ipv6Addr {
     }
 }
 
-#[unstable(feature = "i128", issue = "35118")]
+#[stable(feature = "i128", since = "1.26.0")]
 impl From<Ipv6Addr> for u128 {
     fn from(ip: Ipv6Addr) -> u128 {
         let ip = ip.segments();
@@ -1355,7 +1400,7 @@ impl From<Ipv6Addr> for u128 {
             ((ip[6] as u128) << 16) + (ip[7] as u128)
     }
 }
-#[unstable(feature = "i128", issue = "35118")]
+#[stable(feature = "i128", since = "1.26.0")]
 impl From<u128> for Ipv6Addr {
     fn from(ip: u128) -> Ipv6Addr {
         Ipv6Addr::new(
@@ -1386,6 +1431,27 @@ impl From<[u16; 8]> for Ipv6Addr {
 
 #[stable(feature = "ip_from_slice", since = "1.17.0")]
 impl From<[u8; 16]> for IpAddr {
+    /// Create an `IpAddr::V6` from a sixteen element byte array.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::{IpAddr, Ipv6Addr};
+    ///
+    /// let addr = IpAddr::from([
+    ///     25u8, 24u8, 23u8, 22u8, 21u8, 20u8, 19u8, 18u8,
+    ///     17u8, 16u8, 15u8, 14u8, 13u8, 12u8, 11u8, 10u8,
+    /// ]);
+    /// assert_eq!(
+    ///     IpAddr::V6(Ipv6Addr::new(
+    ///         0x1918, 0x1716,
+    ///         0x1514, 0x1312,
+    ///         0x1110, 0x0f0e,
+    ///         0x0d0c, 0x0b0a
+    ///     )),
+    ///     addr
+    /// );
+    /// ```
     fn from(octets: [u8; 16]) -> IpAddr {
         IpAddr::V6(Ipv6Addr::from(octets))
     }
@@ -1393,6 +1459,27 @@ impl From<[u8; 16]> for IpAddr {
 
 #[stable(feature = "ip_from_slice", since = "1.17.0")]
 impl From<[u16; 8]> for IpAddr {
+    /// Create an `IpAddr::V6` from an eight element 16-bit array.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::{IpAddr, Ipv6Addr};
+    ///
+    /// let addr = IpAddr::from([
+    ///     525u16, 524u16, 523u16, 522u16,
+    ///     521u16, 520u16, 519u16, 518u16,
+    /// ]);
+    /// assert_eq!(
+    ///     IpAddr::V6(Ipv6Addr::new(
+    ///         0x20d, 0x20c,
+    ///         0x20b, 0x20a,
+    ///         0x209, 0x208,
+    ///         0x207, 0x206
+    ///     )),
+    ///     addr
+    /// );
+    /// ```
     fn from(segments: [u16; 8]) -> IpAddr {
         IpAddr::V6(Ipv6Addr::from(segments))
     }
diff --git a/ctr-std/src/net/mod.rs b/ctr-std/src/net/mod.rs
index 9fcb93e..b0d5e56 100644
--- a/ctr-std/src/net/mod.rs
+++ b/ctr-std/src/net/mod.rs
@@ -134,12 +134,15 @@ fn each_addr<A: ToSocketAddrs, F, T>(addr: A, mut f: F) -> io::Result<T>
                                               iterator and returning socket \
                                               addresses",
            issue = "27705")]
+#[rustc_deprecated(since = "1.25.0", reason = "Use the ToSocketAddrs trait instead")]
 pub struct LookupHost(net_imp::LookupHost);
 
 #[unstable(feature = "lookup_host", reason = "unsure about the returned \
                                               iterator and returning socket \
                                               addresses",
            issue = "27705")]
+#[rustc_deprecated(since = "1.25.0", reason = "Use the ToSocketAddrs trait instead")]
+#[allow(deprecated)]
 impl Iterator for LookupHost {
     type Item = SocketAddr;
     fn next(&mut self) -> Option<SocketAddr> { self.0.next() }
@@ -149,6 +152,8 @@ impl Iterator for LookupHost {
                                               iterator and returning socket \
                                               addresses",
            issue = "27705")]
+#[rustc_deprecated(since = "1.25.0", reason = "Use the ToSocketAddrs trait instead")]
+#[allow(deprecated)]
 impl fmt::Debug for LookupHost {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("LookupHost { .. }")
@@ -170,17 +175,19 @@ impl fmt::Debug for LookupHost {
 ///
 /// use std::net;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// for host in net::lookup_host("rust-lang.org")? {
-///     println!("found address: {}", host);
+/// fn main() -> std::io::Result<()> {
+///     for host in net::lookup_host("rust-lang.org")? {
+///         println!("found address: {}", host);
+///     }
+///     Ok(())
 /// }
-/// # Ok(())
-/// # }
 /// ```
 #[unstable(feature = "lookup_host", reason = "unsure about the returned \
                                               iterator and returning socket \
                                               addresses",
            issue = "27705")]
+#[rustc_deprecated(since = "1.25.0", reason = "Use the ToSocketAddrs trait instead")]
+#[allow(deprecated)]
 pub fn lookup_host(host: &str) -> io::Result<LookupHost> {
     net_imp::lookup_host(host).map(LookupHost)
 }
diff --git a/ctr-std/src/net/parser.rs b/ctr-std/src/net/parser.rs
index 261d44e..ae5037c 100644
--- a/ctr-std/src/net/parser.rs
+++ b/ctr-std/src/net/parser.rs
@@ -372,6 +372,25 @@ impl FromStr for SocketAddr {
 /// [`IpAddr`], [`Ipv4Addr`], [`Ipv6Addr`], [`SocketAddr`], [`SocketAddrV4`], and
 /// [`SocketAddrV6`].
 ///
+/// # Potential causes
+///
+/// `AddrParseError` may be thrown because the provided string does not parse as the given type,
+/// often because it includes information only handled by a different address type.
+///
+/// ```should_panic
+/// use std::net::IpAddr;
+/// let _foo: IpAddr = "127.0.0.1:8080".parse().expect("Cannot handle the socket port");
+/// ```
+///
+/// [`IpAddr`] doesn't handle the port. Use [`SocketAddr`] instead.
+///
+/// ```
+/// use std::net::SocketAddr;
+///
+/// // No problem, the `panic!` message has disappeared.
+/// let _foo: SocketAddr = "127.0.0.1:8080".parse().expect("unreachable panic");
+/// ```
+///
 /// [`FromStr`]: ../../std/str/trait.FromStr.html
 /// [`IpAddr`]: ../../std/net/enum.IpAddr.html
 /// [`Ipv4Addr`]: ../../std/net/struct.Ipv4Addr.html
diff --git a/ctr-std/src/net/tcp.rs b/ctr-std/src/net/tcp.rs
index 78235ea..0f60b5b 100644
--- a/ctr-std/src/net/tcp.rs
+++ b/ctr-std/src/net/tcp.rs
@@ -72,7 +72,7 @@ pub struct TcpStream(net_imp::TcpStream);
 ///
 /// # Examples
 ///
-/// ```
+/// ```no_run
 /// # use std::io;
 /// use std::net::{TcpListener, TcpStream};
 ///
@@ -80,15 +80,15 @@ pub struct TcpStream(net_imp::TcpStream);
 ///     // ...
 /// }
 ///
-/// # fn process() -> io::Result<()> {
-/// let listener = TcpListener::bind("127.0.0.1:80").unwrap();
+/// fn main() -> io::Result<()> {
+///     let listener = TcpListener::bind("127.0.0.1:80").unwrap();
 ///
-/// // accept connections and process them serially
-/// for stream in listener.incoming() {
-///     handle_client(stream?);
+///     // accept connections and process them serially
+///     for stream in listener.incoming() {
+///         handle_client(stream?);
+///     }
+///     Ok(())
 /// }
-/// # Ok(())
-/// # }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct TcpListener(net_imp::TcpListener);
@@ -259,19 +259,21 @@ impl TcpStream {
     /// Sets the read timeout to the timeout specified.
     ///
     /// If the value specified is [`None`], then [`read`] calls will block
-    /// indefinitely. It is an error to pass the zero `Duration` to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
-    /// # Note
+    /// # Platform-specific behavior
     ///
     /// Platforms may return a different error code whenever a read times out as
     /// a result of setting this option. For example Unix typically returns an
     /// error of the kind [`WouldBlock`], but Windows may return [`TimedOut`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`read`]: ../../std/io/trait.Read.html#tymethod.read
     /// [`WouldBlock`]: ../../std/io/enum.ErrorKind.html#variant.WouldBlock
     /// [`TimedOut`]: ../../std/io/enum.ErrorKind.html#variant.TimedOut
+    /// [`Duration`]: ../../std/time/struct.Duration.html
     ///
     /// # Examples
     ///
@@ -282,6 +284,20 @@ impl TcpStream {
     ///                        .expect("Couldn't connect to the server...");
     /// stream.set_read_timeout(None).expect("set_read_timeout call failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::TcpStream;
+    /// use std::time::Duration;
+    ///
+    /// let stream = TcpStream::connect("127.0.0.1:8080").unwrap();
+    /// let result = stream.set_read_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "socket_timeout", since = "1.4.0")]
     pub fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         self.0.set_read_timeout(dur)
@@ -290,16 +306,17 @@ impl TcpStream {
     /// Sets the write timeout to the timeout specified.
     ///
     /// If the value specified is [`None`], then [`write`] calls will block
-    /// indefinitely. It is an error to pass the zero [`Duration`] to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
-    /// # Note
+    /// # Platform-specific behavior
     ///
     /// Platforms may return a different error code whenever a write times out
     /// as a result of setting this option. For example Unix typically returns
     /// an error of the kind [`WouldBlock`], but Windows may return [`TimedOut`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`write`]: ../../std/io/trait.Write.html#tymethod.write
     /// [`Duration`]: ../../std/time/struct.Duration.html
     /// [`WouldBlock`]: ../../std/io/enum.ErrorKind.html#variant.WouldBlock
@@ -314,6 +331,20 @@ impl TcpStream {
     ///                        .expect("Couldn't connect to the server...");
     /// stream.set_write_timeout(None).expect("set_write_timeout call failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::TcpStream;
+    /// use std::time::Duration;
+    ///
+    /// let stream = TcpStream::connect("127.0.0.1:8080").unwrap();
+    /// let result = stream.set_write_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "socket_timeout", since = "1.4.0")]
     pub fn set_write_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         self.0.set_write_timeout(dur)
@@ -323,7 +354,7 @@ impl TcpStream {
     ///
     /// If the timeout is [`None`], then [`read`] calls will block indefinitely.
     ///
-    /// # Note
+    /// # Platform-specific behavior
     ///
     /// Some platforms do not provide access to the current timeout.
     ///
@@ -349,7 +380,7 @@ impl TcpStream {
     ///
     /// If the timeout is [`None`], then [`write`] calls will block indefinitely.
     ///
-    /// # Note
+    /// # Platform-specific behavior
     ///
     /// Some platforms do not provide access to the current timeout.
     ///
@@ -1545,6 +1576,26 @@ mod tests {
         drop(listener);
     }
 
+    // Ensure the `set_read_timeout` and `set_write_timeout` calls return errors
+    // when passed zero Durations
+    #[test]
+    fn test_timeout_zero_duration() {
+        let addr = next_test_ip4();
+
+        let listener = t!(TcpListener::bind(&addr));
+        let stream = t!(TcpStream::connect(&addr));
+
+        let result = stream.set_write_timeout(Some(Duration::new(0, 0)));
+        let err = result.unwrap_err();
+        assert_eq!(err.kind(), ErrorKind::InvalidInput);
+
+        let result = stream.set_read_timeout(Some(Duration::new(0, 0)));
+        let err = result.unwrap_err();
+        assert_eq!(err.kind(), ErrorKind::InvalidInput);
+
+        drop(listener);
+    }
+
     #[test]
     fn nodelay() {
         let addr = next_test_ip4();
diff --git a/ctr-std/src/net/udp.rs b/ctr-std/src/net/udp.rs
index fc7f920..d25e299 100644
--- a/ctr-std/src/net/udp.rs
+++ b/ctr-std/src/net/udp.rs
@@ -44,22 +44,22 @@ use time::Duration;
 /// ```no_run
 /// use std::net::UdpSocket;
 ///
-/// # fn foo() -> std::io::Result<()> {
-/// {
-///     let mut socket = UdpSocket::bind("127.0.0.1:34254")?;
+/// fn main() -> std::io::Result<()> {
+///     {
+///         let mut socket = UdpSocket::bind("127.0.0.1:34254")?;
 ///
-///     // Receives a single datagram message on the socket. If `buf` is too small to hold
-///     // the message, it will be cut off.
-///     let mut buf = [0; 10];
-///     let (amt, src) = socket.recv_from(&mut buf)?;
+///         // Receives a single datagram message on the socket. If `buf` is too small to hold
+///         // the message, it will be cut off.
+///         let mut buf = [0; 10];
+///         let (amt, src) = socket.recv_from(&mut buf)?;
 ///
-///     // Redeclare `buf` as slice of the received data and send reverse data back to origin.
-///     let buf = &mut buf[..amt];
-///     buf.reverse();
-///     socket.send_to(buf, &src)?;
-///     # Ok(())
-/// } // the socket is closed here
-/// # }
+///         // Redeclare `buf` as slice of the received data and send reverse data back to origin.
+///         let buf = &mut buf[..amt];
+///         buf.reverse();
+///         socket.send_to(buf, &src)?;
+///     } // the socket is closed here
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct UdpSocket(net_imp::UdpSocket);
@@ -228,16 +228,17 @@ impl UdpSocket {
     /// Sets the read timeout to the timeout specified.
     ///
     /// If the value specified is [`None`], then [`read`] calls will block
-    /// indefinitely. It is an error to pass the zero [`Duration`] to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
-    /// # Note
+    /// # Platform-specific behavior
     ///
     /// Platforms may return a different error code whenever a read times out as
     /// a result of setting this option. For example Unix typically returns an
     /// error of the kind [`WouldBlock`], but Windows may return [`TimedOut`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`read`]: ../../std/io/trait.Read.html#tymethod.read
     /// [`Duration`]: ../../std/time/struct.Duration.html
     /// [`WouldBlock`]: ../../std/io/enum.ErrorKind.html#variant.WouldBlock
@@ -251,6 +252,20 @@ impl UdpSocket {
     /// let socket = UdpSocket::bind("127.0.0.1:34254").expect("couldn't bind to address");
     /// socket.set_read_timeout(None).expect("set_read_timeout call failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::UdpSocket;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:34254").unwrap();
+    /// let result = socket.set_read_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "socket_timeout", since = "1.4.0")]
     pub fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         self.0.set_read_timeout(dur)
@@ -259,16 +274,17 @@ impl UdpSocket {
     /// Sets the write timeout to the timeout specified.
     ///
     /// If the value specified is [`None`], then [`write`] calls will block
-    /// indefinitely. It is an error to pass the zero [`Duration`] to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
-    /// # Note
+    /// # Platform-specific behavior
     ///
     /// Platforms may return a different error code whenever a write times out
     /// as a result of setting this option. For example Unix typically returns
     /// an error of the kind [`WouldBlock`], but Windows may return [`TimedOut`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`write`]: ../../std/io/trait.Write.html#tymethod.write
     /// [`Duration`]: ../../std/time/struct.Duration.html
     /// [`WouldBlock`]: ../../std/io/enum.ErrorKind.html#variant.WouldBlock
@@ -282,6 +298,20 @@ impl UdpSocket {
     /// let socket = UdpSocket::bind("127.0.0.1:34254").expect("couldn't bind to address");
     /// socket.set_write_timeout(None).expect("set_write_timeout call failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::UdpSocket;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:34254").unwrap();
+    /// let result = socket.set_write_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "socket_timeout", since = "1.4.0")]
     pub fn set_write_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         self.0.set_write_timeout(dur)
@@ -1024,6 +1054,23 @@ mod tests {
         assert!(start.elapsed() > Duration::from_millis(400));
     }
 
+    // Ensure the `set_read_timeout` and `set_write_timeout` calls return errors
+    // when passed zero Durations
+    #[test]
+    fn test_timeout_zero_duration() {
+        let addr = next_test_ip4();
+
+        let socket = t!(UdpSocket::bind(&addr));
+
+        let result = socket.set_write_timeout(Some(Duration::new(0, 0)));
+        let err = result.unwrap_err();
+        assert_eq!(err.kind(), ErrorKind::InvalidInput);
+
+        let result = socket.set_read_timeout(Some(Duration::new(0, 0)));
+        let err = result.unwrap_err();
+        assert_eq!(err.kind(), ErrorKind::InvalidInput);
+    }
+
     #[test]
     fn connect_send_recv() {
         let addr = next_test_ip4();
diff --git a/ctr-std/src/num.rs b/ctr-std/src/num.rs
index a2c1339..4b975dd 100644
--- a/ctr-std/src/num.rs
+++ b/ctr-std/src/num.rs
@@ -21,6 +21,13 @@ pub use core::num::{FpCategory, ParseIntError, ParseFloatError, TryFromIntError}
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::num::Wrapping;
 
+#[unstable(feature = "nonzero", issue = "49137")]
+#[allow(deprecated)]
+pub use core::num::{
+    NonZeroU8, NonZeroI8, NonZeroU16, NonZeroI16, NonZeroU32, NonZeroI32,
+    NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize,
+};
+
 #[cfg(test)] use fmt;
 #[cfg(test)] use ops::{Add, Sub, Mul, Div, Rem};
 
@@ -169,7 +176,6 @@ mod tests {
 
     macro_rules! test_checked_next_power_of_two {
         ($test_name:ident, $T:ident) => (
-            #[cfg_attr(target_os = "emscripten", ignore)] // FIXME(#39119)
             fn $test_name() {
                 #![test]
                 assert_eq!((0 as $T).checked_next_power_of_two(), Some(1));
diff --git a/ctr-std/src/panic.rs b/ctr-std/src/panic.rs
index 5608760..28c1783 100644
--- a/ctr-std/src/panic.rs
+++ b/ctr-std/src/panic.rs
@@ -23,7 +23,10 @@ use sync::{Arc, Mutex, RwLock, atomic};
 use thread::Result;
 
 #[stable(feature = "panic_hooks", since = "1.10.0")]
-pub use panicking::{take_hook, set_hook, PanicInfo, Location};
+pub use panicking::{take_hook, set_hook};
+
+#[stable(feature = "panic_hooks", since = "1.10.0")]
+pub use core::panic::{PanicInfo, Location};
 
 /// A marker trait which represents "panic safe" types in Rust.
 ///
@@ -185,7 +188,7 @@ pub struct AssertUnwindSafe<T>(
 // * By default everything is unwind safe
 // * pointers T contains mutability of some form are not unwind safe
 // * Unique, an owning pointer, lifts an implementation
-// * Types like Mutex/RwLock which are explicilty poisoned are unwind safe
+// * Types like Mutex/RwLock which are explicitly poisoned are unwind safe
 // * Our custom AssertUnwindSafe wrapper is indeed unwind safe
 
 #[stable(feature = "catch_unwind", since = "1.9.0")]
@@ -198,7 +201,7 @@ impl<T: RefUnwindSafe + ?Sized> UnwindSafe for *const T {}
 impl<T: RefUnwindSafe + ?Sized> UnwindSafe for *mut T {}
 #[unstable(feature = "ptr_internals", issue = "0")]
 impl<T: UnwindSafe + ?Sized> UnwindSafe for Unique<T> {}
-#[stable(feature = "nonnull", since = "1.24.0")]
+#[stable(feature = "nonnull", since = "1.25.0")]
 impl<T: RefUnwindSafe + ?Sized> UnwindSafe for NonNull<T> {}
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 impl<T: ?Sized> UnwindSafe for Mutex<T> {}
diff --git a/ctr-std/src/primitive_docs.rs b/ctr-std/src/primitive_docs.rs
index a2caf47..ce4bbff 100644
--- a/ctr-std/src/primitive_docs.rs
+++ b/ctr-std/src/primitive_docs.rs
@@ -79,7 +79,6 @@ mod prim_bool { }
 /// write:
 ///
 /// ```
-/// #![feature(never_type)]
 /// # fn foo() -> u32 {
 /// let x: ! = {
 ///     return 123
@@ -131,13 +130,15 @@ mod prim_bool { }
 /// [`Result<String, !>`] which we can unpack like this:
 ///
 /// ```ignore (string-from-str-error-type-is-not-never-yet)
+/// #[feature(exhaustive_patterns)]
 /// // NOTE: This does not work today!
 /// let Ok(s) = String::from_str("hello");
 /// ```
 ///
-/// Since the [`Err`] variant contains a `!`, it can never occur. So we can exhaustively match on
-/// [`Result<T, !>`] by just taking the [`Ok`] variant. This illustrates another behaviour of `!` -
-/// it can be used to "delete" certain enum variants from generic types like `Result`.
+/// Since the [`Err`] variant contains a `!`, it can never occur. If the `exhaustive_patterns`
+/// feature is present this means we can exhaustively match on [`Result<T, !>`] by just taking the
+/// [`Ok`] variant. This illustrates another behaviour of `!` - it can be used to "delete" certain
+/// enum variants from generic types like `Result`.
 ///
 /// [`String::from_str`]: str/trait.FromStr.html#tymethod.from_str
 /// [`Result<String, !>`]: result/enum.Result.html
@@ -154,7 +155,6 @@ mod prim_bool { }
 /// for example:
 ///
 /// ```
-/// # #![feature(never_type)]
 /// # use std::fmt;
 /// # trait Debug {
 /// # fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result;
@@ -192,7 +192,6 @@ mod prim_bool { }
 /// [`Default`]: default/trait.Default.html
 /// [`default()`]: default/trait.Default.html#tymethod.default
 ///
-#[unstable(feature = "never_type", issue = "35121")]
 mod prim_never { }
 
 #[doc(primitive = "char")]
@@ -720,10 +719,6 @@ mod prim_f64 { }
 /// The 8-bit signed integer type.
 ///
 /// *[See also the `std::i8` module](i8/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `i64` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_i8 { }
 
@@ -732,10 +727,6 @@ mod prim_i8 { }
 /// The 16-bit signed integer type.
 ///
 /// *[See also the `std::i16` module](i16/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `i32` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_i16 { }
 
@@ -744,10 +735,6 @@ mod prim_i16 { }
 /// The 32-bit signed integer type.
 ///
 /// *[See also the `std::i32` module](i32/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `i16` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_i32 { }
 
@@ -756,10 +743,6 @@ mod prim_i32 { }
 /// The 64-bit signed integer type.
 ///
 /// *[See also the `std::i64` module](i64/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `i8` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_i64 { }
 
@@ -768,11 +751,7 @@ mod prim_i64 { }
 /// The 128-bit signed integer type.
 ///
 /// *[See also the `std::i128` module](i128/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `i8` in there.
-///
-#[unstable(feature = "i128", issue="35118")]
+#[stable(feature = "i128", since="1.26.0")]
 mod prim_i128 { }
 
 #[doc(primitive = "u8")]
@@ -780,10 +759,6 @@ mod prim_i128 { }
 /// The 8-bit unsigned integer type.
 ///
 /// *[See also the `std::u8` module](u8/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `u64` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_u8 { }
 
@@ -792,10 +767,6 @@ mod prim_u8 { }
 /// The 16-bit unsigned integer type.
 ///
 /// *[See also the `std::u16` module](u16/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `u32` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_u16 { }
 
@@ -804,10 +775,6 @@ mod prim_u16 { }
 /// The 32-bit unsigned integer type.
 ///
 /// *[See also the `std::u32` module](u32/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `u16` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_u32 { }
 
@@ -816,10 +783,6 @@ mod prim_u32 { }
 /// The 64-bit unsigned integer type.
 ///
 /// *[See also the `std::u64` module](u64/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `u8` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_u64 { }
 
@@ -828,11 +791,7 @@ mod prim_u64 { }
 /// The 128-bit unsigned integer type.
 ///
 /// *[See also the `std::u128` module](u128/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `u8` in there.
-///
-#[unstable(feature = "i128", issue="35118")]
+#[stable(feature = "i128", since="1.26.0")]
 mod prim_u128 { }
 
 #[doc(primitive = "isize")]
@@ -844,10 +803,6 @@ mod prim_u128 { }
 /// and on a 64 bit target, this is 8 bytes.
 ///
 /// *[See also the `std::isize` module](isize/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `usize` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_isize { }
 
@@ -860,10 +815,6 @@ mod prim_isize { }
 /// and on a 64 bit target, this is 8 bytes.
 ///
 /// *[See also the `std::usize` module](usize/index.html).*
-///
-/// However, please note that examples are shared between primitive integer
-/// types. So it's normal if you see usage of types like `isize` in there.
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_usize { }
 
diff --git a/ctr-std/src/process.rs b/ctr-std/src/process.rs
index 5c66ac6..92f0406 100644
--- a/ctr-std/src/process.rs
+++ b/ctr-std/src/process.rs
@@ -1080,6 +1080,46 @@ impl fmt::Display for ExitStatus {
     }
 }
 
+/// This type represents the status code a process can return to its
+/// parent under normal termination.
+///
+/// Numeric values used in this type don't have portable meanings, and
+/// different platforms may mask different amounts of them.
+///
+/// For the platform's canonical successful and unsuccessful codes, see
+/// the [`SUCCESS`] and [`FAILURE`] associated items.
+///
+/// [`SUCCESS`]: #associatedconstant.SUCCESS
+/// [`FAILURE`]: #associatedconstant.FAILURE
+///
+/// **Warning**: While various forms of this were discussed in [RFC #1937],
+/// it was ultimately cut from that RFC, and thus this type is more subject
+/// to change even than the usual unstable item churn.
+///
+/// [RFC #1937]: https://github.com/rust-lang/rfcs/pull/1937
+#[derive(Clone, Copy, Debug)]
+#[unstable(feature = "process_exitcode_placeholder", issue = "48711")]
+pub struct ExitCode(imp::ExitCode);
+
+#[unstable(feature = "process_exitcode_placeholder", issue = "48711")]
+impl ExitCode {
+    /// The canonical ExitCode for successful termination on this platform.
+    ///
+    /// Note that a `()`-returning `main` implicitly results in a successful
+    /// termination, so there's no need to return this from `main` unless
+    /// you're also returning other possible codes.
+    #[unstable(feature = "process_exitcode_placeholder", issue = "48711")]
+    pub const SUCCESS: ExitCode = ExitCode(imp::ExitCode::SUCCESS);
+
+    /// The canonical ExitCode for unsuccessful termination on this platform.
+    ///
+    /// If you're only returning this and `SUCCESS` from `main`, consider
+    /// instead returning `Err(_)` and `Ok(())` respectively, which will
+    /// return the same codes (but will also `eprintln!` the error).
+    #[unstable(feature = "process_exitcode_placeholder", issue = "48711")]
+    pub const FAILURE: ExitCode = ExitCode(imp::ExitCode::FAILURE);
+}
+
 impl Child {
     /// Forces the child to exit. This is equivalent to sending a
     /// SIGKILL on unix platforms.
@@ -1380,18 +1420,74 @@ pub fn abort() -> ! {
 /// Basic usage:
 ///
 /// ```no_run
-/// #![feature(getpid)]
 /// use std::process;
 ///
 /// println!("My pid is {}", process::id());
 /// ```
 ///
 ///
-#[unstable(feature = "getpid", issue = "44971", reason = "recently added")]
+#[stable(feature = "getpid", since = "1.26.0")]
 pub fn id() -> u32 {
     ::sys::os::getpid()
 }
 
+/// A trait for implementing arbitrary return types in the `main` function.
+///
+/// The c-main function only supports to return integers as return type.
+/// So, every type implementing the `Termination` trait has to be converted
+/// to an integer.
+///
+/// The default implementations are returning `libc::EXIT_SUCCESS` to indicate
+/// a successful execution. In case of a failure, `libc::EXIT_FAILURE` is returned.
+#[cfg_attr(not(test), lang = "termination")]
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+#[rustc_on_unimplemented(
+  message="`main` has invalid return type `{Self}`",
+  label="`main` can only return types that implement `{Termination}`")]
+pub trait Termination {
+    /// Is called to get the representation of the value as status code.
+    /// This status code is returned to the operating system.
+    fn report(self) -> i32;
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl Termination for () {
+    #[inline]
+    fn report(self) -> i32 { ExitCode::SUCCESS.report() }
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl<E: fmt::Debug> Termination for Result<(), E> {
+    fn report(self) -> i32 {
+        match self {
+            Ok(()) => ().report(),
+            Err(err) => Err::<!, _>(err).report(),
+        }
+    }
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl Termination for ! {
+    fn report(self) -> i32 { self }
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl<E: fmt::Debug> Termination for Result<!, E> {
+    fn report(self) -> i32 {
+        let Err(err) = self;
+        eprintln!("Error: {:?}", err);
+        ExitCode::FAILURE.report()
+    }
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl Termination for ExitCode {
+    #[inline]
+    fn report(self) -> i32 {
+        self.0.as_i32()
+    }
+}
+
 #[cfg(all(test, not(any(target_os = "cloudabi", target_os = "emscripten"))))]
 mod tests {
     use io::prelude::*;
@@ -1843,4 +1939,10 @@ mod tests {
         }
         assert!(events > 0);
     }
+
+    #[test]
+    fn test_command_implements_send() {
+        fn take_send_type<T: Send>(_: T) {}
+        take_send_type(Command::new(""))
+    }
 }
diff --git a/ctr-std/src/rt.rs b/ctr-std/src/rt.rs
index 9dbaf78..e139276 100644
--- a/ctr-std/src/rt.rs
+++ b/ctr-std/src/rt.rs
@@ -68,7 +68,7 @@ fn lang_start_internal(main: &(Fn() -> i32 + Sync + ::panic::RefUnwindSafe),
 
 #[cfg(not(test))]
 #[lang = "start"]
-fn lang_start<T: ::termination::Termination + 'static>
+fn lang_start<T: ::process::Termination + 'static>
     (main: fn() -> T, argc: isize, argv: *const *const u8) -> isize
 {
     lang_start_internal(&move || main().report(), argc, argv)
diff --git a/ctr-std/src/sync/condvar.rs b/ctr-std/src/sync/condvar.rs
index 5640217..3014283 100644
--- a/ctr-std/src/sync/condvar.rs
+++ b/ctr-std/src/sync/condvar.rs
@@ -14,7 +14,7 @@ use sync::{mutex, MutexGuard, PoisonError};
 use sys_common::condvar as sys;
 use sys_common::mutex as sys_mutex;
 use sys_common::poison::{self, LockResult};
-use time::Duration;
+use time::{Duration, Instant};
 
 /// A type indicating whether a timed wait on a condition variable returned
 /// due to a time out or not.
@@ -47,11 +47,13 @@ impl WaitTimeoutResult {
     ///
     /// thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
+    ///
+    ///     // Let's wait 20 milliseconds before notifying the condvar.
+    ///     thread::sleep(Duration::from_millis(20));
+    ///
     ///     let mut started = lock.lock().unwrap();
     ///     // We update the boolean value.
     ///     *started = true;
-    ///     // Let's wait 20 milliseconds before notifying the condvar.
-    ///     thread::sleep(Duration::from_millis(20));
     ///     cvar.notify_one();
     /// });
     ///
@@ -219,6 +221,64 @@ impl Condvar {
         }
     }
 
+    /// Blocks the current thread until this condition variable receives a
+    /// notification and the required condition is met. Spurious wakeups are
+    /// ignored and this function will only return once the condition has been
+    /// met.
+    ///
+    /// This function will atomically unlock the mutex specified (represented by
+    /// `guard`) and block the current thread. This means that any calls
+    /// to [`notify_one`] or [`notify_all`] which happen logically after the
+    /// mutex is unlocked are candidates to wake this thread up. When this
+    /// function call returns, the lock specified will have been re-acquired.
+    ///
+    /// # Errors
+    ///
+    /// This function will return an error if the mutex being waited on is
+    /// poisoned when this thread re-acquires the lock. For more information,
+    /// see information about [poisoning] on the [`Mutex`] type.
+    ///
+    /// [`notify_one`]: #method.notify_one
+    /// [`notify_all`]: #method.notify_all
+    /// [poisoning]: ../sync/struct.Mutex.html#poisoning
+    /// [`Mutex`]: ../sync/struct.Mutex.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(wait_until)]
+    ///
+    /// use std::sync::{Arc, Mutex, Condvar};
+    /// use std::thread;
+    ///
+    /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
+    /// let pair2 = pair.clone();
+    ///
+    /// thread::spawn(move|| {
+    ///     let &(ref lock, ref cvar) = &*pair2;
+    ///     let mut started = lock.lock().unwrap();
+    ///     *started = true;
+    ///     // We notify the condvar that the value has changed.
+    ///     cvar.notify_one();
+    /// });
+    ///
+    /// // Wait for the thread to start up.
+    /// let &(ref lock, ref cvar) = &*pair;
+    /// // As long as the value inside the `Mutex` is false, we wait.
+    /// let _guard = cvar.wait_until(lock.lock().unwrap(), |started| { *started }).unwrap();
+    /// ```
+    #[unstable(feature = "wait_until", issue = "47960")]
+    pub fn wait_until<'a, T, F>(&self, mut guard: MutexGuard<'a, T>,
+                                mut condition: F)
+                                -> LockResult<MutexGuard<'a, T>>
+                                where F: FnMut(&mut T) -> bool {
+        while !condition(&mut *guard) {
+            guard = self.wait(guard)?;
+        }
+        Ok(guard)
+    }
+
+
     /// Waits on this condition variable for a notification, timing out after a
     /// specified duration.
     ///
@@ -293,7 +353,15 @@ impl Condvar {
     ///
     /// Note that the best effort is made to ensure that the time waited is
     /// measured with a monotonic clock, and not affected by the changes made to
-    /// the system time.
+    /// the system time.  This function is susceptible to spurious wakeups.
+    /// Condition variables normally have a boolean predicate associated with
+    /// them, and the predicate must always be checked each time this function
+    /// returns to protect against spurious wakeups.  Additionally, it is
+    /// typically desirable for the time-out to not exceed some duration in
+    /// spite of spurious wakes, thus the sleep-duration is decremented by the
+    /// amount slept.  Alternatively, use the `wait_timeout_until` method
+    /// to wait until a condition is met with a total time-out regardless
+    /// of spurious wakes.
     ///
     /// The returned [`WaitTimeoutResult`] value indicates if the timeout is
     /// known to have elapsed.
@@ -302,6 +370,7 @@ impl Condvar {
     /// returns, regardless of whether the timeout elapsed or not.
     ///
     /// [`wait`]: #method.wait
+    /// [`wait_timeout_until`]: #method.wait_timeout_until
     /// [`WaitTimeoutResult`]: struct.WaitTimeoutResult.html
     ///
     /// # Examples
@@ -353,6 +422,80 @@ impl Condvar {
         }
     }
 
+    /// Waits on this condition variable for a notification, timing out after a
+    /// specified duration.  Spurious wakes will not cause this function to
+    /// return.
+    ///
+    /// The semantics of this function are equivalent to [`wait_until`] except
+    /// that the thread will be blocked for roughly no longer than `dur`. This
+    /// method should not be used for precise timing due to anomalies such as
+    /// preemption or platform differences that may not cause the maximum
+    /// amount of time waited to be precisely `dur`.
+    ///
+    /// Note that the best effort is made to ensure that the time waited is
+    /// measured with a monotonic clock, and not affected by the changes made to
+    /// the system time.
+    ///
+    /// The returned [`WaitTimeoutResult`] value indicates if the timeout is
+    /// known to have elapsed without the condition being met.
+    ///
+    /// Like [`wait_until`], the lock specified will be re-acquired when this
+    /// function returns, regardless of whether the timeout elapsed or not.
+    ///
+    /// [`wait_until`]: #method.wait_until
+    /// [`wait_timeout`]: #method.wait_timeout
+    /// [`WaitTimeoutResult`]: struct.WaitTimeoutResult.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(wait_timeout_until)]
+    ///
+    /// use std::sync::{Arc, Mutex, Condvar};
+    /// use std::thread;
+    /// use std::time::Duration;
+    ///
+    /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
+    /// let pair2 = pair.clone();
+    ///
+    /// thread::spawn(move|| {
+    ///     let &(ref lock, ref cvar) = &*pair2;
+    ///     let mut started = lock.lock().unwrap();
+    ///     *started = true;
+    ///     // We notify the condvar that the value has changed.
+    ///     cvar.notify_one();
+    /// });
+    ///
+    /// // wait for the thread to start up
+    /// let &(ref lock, ref cvar) = &*pair;
+    /// let result = cvar.wait_timeout_until(
+    ///     lock.lock().unwrap(),
+    ///     Duration::from_millis(100),
+    ///     |&mut started| started,
+    /// ).unwrap();
+    /// if result.1.timed_out() {
+    ///     // timed-out without the condition ever evaluating to true.
+    /// }
+    /// // access the locked mutex via result.0
+    /// ```
+    #[unstable(feature = "wait_timeout_until", issue = "47960")]
+    pub fn wait_timeout_until<'a, T, F>(&self, mut guard: MutexGuard<'a, T>,
+                                        dur: Duration, mut condition: F)
+                                        -> LockResult<(MutexGuard<'a, T>, WaitTimeoutResult)>
+                                        where F: FnMut(&mut T) -> bool {
+        let start = Instant::now();
+        loop {
+            if condition(&mut *guard) {
+                return Ok((guard, WaitTimeoutResult(false)));
+            }
+            let timeout = match dur.checked_sub(start.elapsed()) {
+                Some(timeout) => timeout,
+                None => return Ok((guard, WaitTimeoutResult(true))),
+            };
+            guard = self.wait_timeout(guard, timeout)?.0;
+        }
+    }
+
     /// Wakes up one blocked thread on this condvar.
     ///
     /// If there is a blocked thread on this condition variable, then it will
@@ -478,6 +621,7 @@ impl Drop for Condvar {
 
 #[cfg(test)]
 mod tests {
+    /// #![feature(wait_until)]
     use sync::mpsc::channel;
     use sync::{Condvar, Mutex, Arc};
     use sync::atomic::{AtomicBool, Ordering};
@@ -548,6 +692,29 @@ mod tests {
 
     #[test]
     #[cfg_attr(target_os = "emscripten", ignore)]
+    fn wait_until() {
+        let pair = Arc::new((Mutex::new(false), Condvar::new()));
+        let pair2 = pair.clone();
+
+        // Inside of our lock, spawn a new thread, and then wait for it to start.
+        thread::spawn(move|| {
+            let &(ref lock, ref cvar) = &*pair2;
+            let mut started = lock.lock().unwrap();
+            *started = true;
+            // We notify the condvar that the value has changed.
+            cvar.notify_one();
+        });
+
+        // Wait for the thread to start up.
+        let &(ref lock, ref cvar) = &*pair;
+        let guard = cvar.wait_until(lock.lock().unwrap(), |started| {
+            *started
+        });
+        assert!(*guard.unwrap());
+    }
+
+    #[test]
+    #[cfg_attr(target_os = "emscripten", ignore)]
     fn wait_timeout_wait() {
         let m = Arc::new(Mutex::new(()));
         let c = Arc::new(Condvar::new());
@@ -567,6 +734,53 @@ mod tests {
 
     #[test]
     #[cfg_attr(target_os = "emscripten", ignore)]
+    fn wait_timeout_until_wait() {
+        let m = Arc::new(Mutex::new(()));
+        let c = Arc::new(Condvar::new());
+
+        let g = m.lock().unwrap();
+        let (_g, wait) = c.wait_timeout_until(g, Duration::from_millis(1), |_| { false }).unwrap();
+        // no spurious wakeups. ensure it timed-out
+        assert!(wait.timed_out());
+    }
+
+    #[test]
+    #[cfg_attr(target_os = "emscripten", ignore)]
+    fn wait_timeout_until_instant_satisfy() {
+        let m = Arc::new(Mutex::new(()));
+        let c = Arc::new(Condvar::new());
+
+        let g = m.lock().unwrap();
+        let (_g, wait) = c.wait_timeout_until(g, Duration::from_millis(0), |_| { true }).unwrap();
+        // ensure it didn't time-out even if we were not given any time.
+        assert!(!wait.timed_out());
+    }
+
+    #[test]
+    #[cfg_attr(target_os = "emscripten", ignore)]
+    fn wait_timeout_until_wake() {
+        let pair = Arc::new((Mutex::new(false), Condvar::new()));
+        let pair_copy = pair.clone();
+
+        let &(ref m, ref c) = &*pair;
+        let g = m.lock().unwrap();
+        let _t = thread::spawn(move || {
+            let &(ref lock, ref cvar) = &*pair_copy;
+            let mut started = lock.lock().unwrap();
+            thread::sleep(Duration::from_millis(1));
+            *started = true;
+            cvar.notify_one();
+        });
+        let (g2, wait) = c.wait_timeout_until(g, Duration::from_millis(u64::MAX), |&mut notified| {
+            notified
+        }).unwrap();
+        // ensure it didn't time-out even if we were not given any time.
+        assert!(!wait.timed_out());
+        assert!(*g2);
+    }
+
+    #[test]
+    #[cfg_attr(target_os = "emscripten", ignore)]
     fn wait_timeout_wake() {
         let m = Arc::new(Mutex::new(()));
         let c = Arc::new(Condvar::new());
diff --git a/ctr-std/src/sync/mod.rs b/ctr-std/src/sync/mod.rs
index 289b47b..642b284 100644
--- a/ctr-std/src/sync/mod.rs
+++ b/ctr-std/src/sync/mod.rs
@@ -18,7 +18,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc::arc::{Arc, Weak};
+pub use alloc_crate::arc::{Arc, Weak};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::sync::atomic;
 
diff --git a/ctr-std/src/sync/mpsc/mpsc_queue.rs b/ctr-std/src/sync/mpsc/mpsc_queue.rs
index 296773d..df945ac 100644
--- a/ctr-std/src/sync/mpsc/mpsc_queue.rs
+++ b/ctr-std/src/sync/mpsc/mpsc_queue.rs
@@ -23,10 +23,9 @@
 
 pub use self::PopResult::*;
 
-use alloc::boxed::Box;
 use core::ptr;
 use core::cell::UnsafeCell;
-
+use boxed::Box;
 use sync::atomic::{AtomicPtr, Ordering};
 
 /// A result of the `pop` function.
diff --git a/ctr-std/src/sync/mpsc/spsc_queue.rs b/ctr-std/src/sync/mpsc/spsc_queue.rs
index cc4be92..9482f69 100644
--- a/ctr-std/src/sync/mpsc/spsc_queue.rs
+++ b/ctr-std/src/sync/mpsc/spsc_queue.rs
@@ -16,7 +16,7 @@
 
 // http://www.1024cores.net/home/lock-free-algorithms/queues/unbounded-spsc-queue
 
-use alloc::boxed::Box;
+use boxed::Box;
 use core::ptr;
 use core::cell::UnsafeCell;
 
diff --git a/ctr-std/src/sync/rwlock.rs b/ctr-std/src/sync/rwlock.rs
index 2edf02e..f7fdedc 100644
--- a/ctr-std/src/sync/rwlock.rs
+++ b/ctr-std/src/sync/rwlock.rs
@@ -24,8 +24,8 @@ use sys_common::rwlock as sys;
 /// typically allows for read-only access (shared access).
 ///
 /// In comparison, a [`Mutex`] does not distinguish between readers or writers
-/// that aquire the lock, therefore blocking any threads waiting for the lock to
-/// become available. An `RwLock` will allow any number of readers to aquire the
+/// that acquire the lock, therefore blocking any threads waiting for the lock to
+/// become available. An `RwLock` will allow any number of readers to acquire the
 /// lock as long as a writer is not holding the lock.
 ///
 /// The priority policy of the lock is dependent on the underlying operating
diff --git a/ctr-std/src/sys/unix/os_str.rs b/ctr-std/src/sys/unix/os_str.rs
index 543c22e..e0da5bd 100644
--- a/ctr-std/src/sys/unix/os_str.rs
+++ b/ctr-std/src/sys/unix/os_str.rs
@@ -19,7 +19,7 @@ use rc::Rc;
 use sync::Arc;
 use sys_common::{AsInner, IntoInner};
 use sys_common::bytestring::debug_fmt_bytestring;
-use std_unicode::lossy::Utf8Lossy;
+use core::str::lossy::Utf8Lossy;
 
 #[derive(Clone, Hash)]
 pub struct Buf {
@@ -104,6 +104,11 @@ impl Buf {
         self.inner.shrink_to_fit()
     }
 
+    #[inline]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.inner.shrink_to(min_capacity)
+    }
+
     pub fn as_slice(&self) -> &Slice {
         unsafe { mem::transmute(&*self.inner) }
     }
diff --git a/ctr-std/src/sys/unix/process.rs b/ctr-std/src/sys/unix/process.rs
index f058aa9..06dafc6 100644
--- a/ctr-std/src/sys/unix/process.rs
+++ b/ctr-std/src/sys/unix/process.rs
@@ -16,6 +16,11 @@ use sys::pipe::AnonPipe;
 use sys::{unsupported, Void};
 use sys_common::process::{CommandEnv, DefaultEnvKey};
 
+use libc::c_int;
+
+const EXIT_SUCCESS: c_int = 0;
+const EXIT_FAILURE: c_int = 1;
+
 ////////////////////////////////////////////////////////////////////////////////
 // Command
 ////////////////////////////////////////////////////////////////////////////////
@@ -149,3 +154,16 @@ impl Process {
         match self.0 {}
     }
 }
+
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+pub struct ExitCode(u8);
+
+impl ExitCode {
+    pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _);
+    pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _);
+
+    #[inline]
+    pub fn as_i32(&self) -> i32 {
+        self.0 as i32
+    }
+}
diff --git a/ctr-std/src/sys/unix/thread.rs b/ctr-std/src/sys/unix/thread.rs
index 76aa55a..694f85a 100644
--- a/ctr-std/src/sys/unix/thread.rs
+++ b/ctr-std/src/sys/unix/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 alloc_crate::boxed::FnBox;
 use libc;
 use cmp;
 use ffi::CStr;
diff --git a/ctr-std/src/sys_common/at_exit_imp.rs b/ctr-std/src/sys_common/at_exit_imp.rs
index ce6fd4c..f511981 100644
--- a/ctr-std/src/sys_common/at_exit_imp.rs
+++ b/ctr-std/src/sys_common/at_exit_imp.rs
@@ -12,7 +12,7 @@
 //!
 //! Documentation can be found on the `rt::at_exit` function.
 
-use alloc::boxed::FnBox;
+use alloc_crate::boxed::FnBox;
 use ptr;
 use sys_common::mutex::Mutex;
 
diff --git a/ctr-std/src/sys_common/bytestring.rs b/ctr-std/src/sys_common/bytestring.rs
index eb9cad0..971b839 100644
--- a/ctr-std/src/sys_common/bytestring.rs
+++ b/ctr-std/src/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/ctr-std/src/sys_common/process.rs b/ctr-std/src/sys_common/process.rs
index fd1a5fd..0a64d78 100644
--- a/ctr-std/src/sys_common/process.rs
+++ b/ctr-std/src/sys_common/process.rs
@@ -14,7 +14,7 @@
 use ffi::{OsStr, OsString};
 use env;
 use collections::BTreeMap;
-use alloc::borrow::Borrow;
+use alloc_crate::borrow::Borrow;
 
 pub trait EnvKey:
     From<OsString> + Into<OsString> +
diff --git a/ctr-std/src/sys_common/thread.rs b/ctr-std/src/sys_common/thread.rs
index f1379b6..cafa353 100644
--- a/ctr-std/src/sys_common/thread.rs
+++ b/ctr-std/src/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 alloc_crate::boxed::FnBox;
 use env;
 use sync::atomic::{self, Ordering};
 use sys::stack_overflow;
diff --git a/ctr-std/src/sys_common/wtf8.rs b/ctr-std/src/sys_common/wtf8.rs
index 46d554d..dda4e1b 100644
--- a/ctr-std/src/sys_common/wtf8.rs
+++ b/ctr-std/src/sys_common/wtf8.rs
@@ -27,7 +27,6 @@
 
 use core::str::next_code_point;
 
-use ascii::*;
 use borrow::Cow;
 use char;
 use fmt;
@@ -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 {
@@ -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,
@@ -876,24 +875,22 @@ impl Hash for Wtf8 {
     }
 }
 
-impl AsciiExt for Wtf8 {
-    type Owned = Wtf8Buf;
-
-    fn is_ascii(&self) -> bool {
+impl Wtf8 {
+    pub fn is_ascii(&self) -> bool {
         self.bytes.is_ascii()
     }
-    fn to_ascii_uppercase(&self) -> Wtf8Buf {
+    pub fn to_ascii_uppercase(&self) -> Wtf8Buf {
         Wtf8Buf { bytes: self.bytes.to_ascii_uppercase() }
     }
-    fn to_ascii_lowercase(&self) -> Wtf8Buf {
+    pub fn to_ascii_lowercase(&self) -> Wtf8Buf {
         Wtf8Buf { bytes: self.bytes.to_ascii_lowercase() }
     }
-    fn eq_ignore_ascii_case(&self, other: &Wtf8) -> bool {
+    pub 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() }
+    pub fn make_ascii_uppercase(&mut self) { self.bytes.make_ascii_uppercase() }
+    pub fn make_ascii_lowercase(&mut self) { self.bytes.make_ascii_lowercase() }
 }
 
 #[cfg(test)]
diff --git a/ctr-std/src/termination.rs b/ctr-std/src/termination.rs
deleted file mode 100644
index e4a577e..0000000
--- a/ctr-std/src/termination.rs
+++ /dev/null
@@ -1,80 +0,0 @@
-// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-use error::Error;
-// TODO: Add these consts to the libc crate for newlib
-mod exit {
-    pub const SUCCESS: i32 = 0;
-    pub const FAILURE: i32 = 1;
-}
-
-/// A trait for implementing arbitrary return types in the `main` function.
-///
-/// The c-main function only supports to return integers as return type.
-/// So, every type implementing the `Termination` trait has to be converted
-/// to an integer.
-///
-/// The default implementations are returning `libc::EXIT_SUCCESS` to indicate
-/// a successful execution. In case of a failure, `libc::EXIT_FAILURE` is returned.
-#[cfg_attr(not(test), lang = "termination")]
-#[unstable(feature = "termination_trait", issue = "43301")]
-#[rustc_on_unimplemented =
-  "`main` can only return types that implement {Termination}, not `{Self}`"]
-pub trait Termination {
-    /// Is called to get the representation of the value as status code.
-    /// This status code is returned to the operating system.
-    fn report(self) -> i32;
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl Termination for () {
-    fn report(self) -> i32 { exit::SUCCESS }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl<T: Termination, E: Error> Termination for Result<T, E> {
-    fn report(self) -> i32 {
-        match self {
-            Ok(val) => val.report(),
-            Err(err) => {
-                print_error(err);
-                exit::FAILURE
-            }
-        }
-    }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-fn print_error<E: Error>(err: E) {
-    eprintln!("Error: {}", err.description());
-
-    if let Some(ref err) = err.cause() {
-        eprintln!("Caused by: {}", err.description());
-    }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl Termination for ! {
-    fn report(self) -> i32 { unreachable!(); }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl Termination for bool {
-    fn report(self) -> i32 {
-        if self { exit::SUCCESS } else { exit::FAILURE }
-    }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl Termination for i32 {
-    fn report(self) -> i32 {
-        self
-    }
-}
diff --git a/ctr-std/src/thread/local.rs b/ctr-std/src/thread/local.rs
index fcbca38..99479bc 100644
--- a/ctr-std/src/thread/local.rs
+++ b/ctr-std/src/thread/local.rs
@@ -195,64 +195,20 @@ macro_rules! __thread_local_inner {
     }
 }
 
-/// Indicator of the state of a thread local storage key.
-#[unstable(feature = "thread_local_state",
-           reason = "state querying was recently added",
-           issue = "27716")]
-#[derive(Debug, Eq, PartialEq, Copy, Clone)]
-pub enum LocalKeyState {
-    /// All keys are in this state whenever a thread starts. Keys will
-    /// transition to the `Valid` state once the first call to [`with`] happens
-    /// and the initialization expression succeeds.
-    ///
-    /// Keys in the `Uninitialized` state will yield a reference to the closure
-    /// passed to [`with`] so long as the initialization routine does not panic.
-    ///
-    /// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
-    Uninitialized,
-
-    /// Once a key has been accessed successfully, it will enter the `Valid`
-    /// state. Keys in the `Valid` state will remain so until the thread exits,
-    /// at which point the destructor will be run and the key will enter the
-    /// `Destroyed` state.
-    ///
-    /// Keys in the `Valid` state will be guaranteed to yield a reference to the
-    /// closure passed to [`with`].
-    ///
-    /// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
-    Valid,
-
-    /// When a thread exits, the destructors for keys will be run (if
-    /// necessary). While a destructor is running, and possibly after a
-    /// destructor has run, a key is in the `Destroyed` state.
-    ///
-    /// Keys in the `Destroyed` states will trigger a panic when accessed via
-    /// [`with`].
-    ///
-    /// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
-    Destroyed,
-}
-
 /// An error returned by [`LocalKey::try_with`](struct.LocalKey.html#method.try_with).
-#[unstable(feature = "thread_local_state",
-           reason = "state querying was recently added",
-           issue = "27716")]
+#[stable(feature = "thread_local_try_with", since = "1.26.0")]
 pub struct AccessError {
     _private: (),
 }
 
-#[unstable(feature = "thread_local_state",
-           reason = "state querying was recently added",
-           issue = "27716")]
+#[stable(feature = "thread_local_try_with", since = "1.26.0")]
 impl fmt::Debug for AccessError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("AccessError").finish()
     }
 }
 
-#[unstable(feature = "thread_local_state",
-           reason = "state querying was recently added",
-           issue = "27716")]
+#[stable(feature = "thread_local_try_with", since = "1.26.0")]
 impl fmt::Display for AccessError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         fmt::Display::fmt("already destroyed", f)
@@ -312,64 +268,21 @@ impl<T: 'static> LocalKey<T> {
         (*ptr).as_ref().unwrap()
     }
 
-    /// Query the current state of this key.
-    ///
-    /// A key is initially in the `Uninitialized` state whenever a thread
-    /// starts. It will remain in this state up until the first call to [`with`]
-    /// within a thread has run the initialization expression successfully.
-    ///
-    /// Once the initialization expression succeeds, the key transitions to the
-    /// `Valid` state which will guarantee that future calls to [`with`] will
-    /// succeed within the thread. Some keys might skip the `Uninitialized`
-    /// state altogether and start in the `Valid` state as an optimization
-    /// (e.g. keys initialized with a constant expression), but no guarantees
-    /// are made.
-    ///
-    /// When a thread exits, each key will be destroyed in turn, and as keys are
-    /// destroyed they will enter the `Destroyed` state just before the
-    /// destructor starts to run. Keys may remain in the `Destroyed` state after
-    /// destruction has completed. Keys without destructors (e.g. with types
-    /// that are [`Copy`]), may never enter the `Destroyed` state.
-    ///
-    /// Keys in the `Uninitialized` state can be accessed so long as the
-    /// initialization does not panic. Keys in the `Valid` state are guaranteed
-    /// to be able to be accessed. Keys in the `Destroyed` state will panic on
-    /// any call to [`with`].
-    ///
-    /// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
-    /// [`Copy`]: ../../std/marker/trait.Copy.html
-    #[unstable(feature = "thread_local_state",
-               reason = "state querying was recently added",
-               issue = "27716")]
-    pub fn state(&'static self) -> LocalKeyState {
-        unsafe {
-            match (self.inner)() {
-                Some(cell) => {
-                    match *cell.get() {
-                        Some(..) => LocalKeyState::Valid,
-                        None => LocalKeyState::Uninitialized,
-                    }
-                }
-                None => LocalKeyState::Destroyed,
-            }
-        }
-    }
-
     /// Acquires a reference to the value in this TLS key.
     ///
     /// This will lazily initialize the value if this thread has not referenced
     /// this key yet. If the key has been destroyed (which may happen if this is called
-    /// in a destructor), this function will return a ThreadLocalError.
+    /// in a destructor), this function will return a `ThreadLocalError`.
     ///
     /// # Panics
     ///
     /// This function will still `panic!()` if the key is uninitialized and the
     /// key's initializer panics.
-    #[unstable(feature = "thread_local_state",
-               reason = "state querying was recently added",
-               issue = "27716")]
+    #[stable(feature = "thread_local_try_with", since = "1.26.0")]
     pub fn try_with<F, R>(&'static self, f: F) -> Result<R, AccessError>
-                      where F: FnOnce(&T) -> R {
+    where
+        F: FnOnce(&T) -> R,
+    {
         unsafe {
             let slot = (self.inner)().ok_or(AccessError {
                 _private: (),
@@ -530,7 +443,6 @@ pub mod os {
 mod tests {
     use sync::mpsc::{channel, Sender};
     use cell::{Cell, UnsafeCell};
-    use super::LocalKeyState;
     use thread;
 
     struct Foo(Sender<()>);
@@ -569,21 +481,13 @@ mod tests {
         struct Foo;
         impl Drop for Foo {
             fn drop(&mut self) {
-                assert!(FOO.state() == LocalKeyState::Destroyed);
+                assert!(FOO.try_with(|_| ()).is_err());
             }
         }
-        fn foo() -> Foo {
-            assert!(FOO.state() == LocalKeyState::Uninitialized);
-            Foo
-        }
-        thread_local!(static FOO: Foo = foo());
+        thread_local!(static FOO: Foo = Foo);
 
         thread::spawn(|| {
-            assert!(FOO.state() == LocalKeyState::Uninitialized);
-            FOO.with(|_| {
-                assert!(FOO.state() == LocalKeyState::Valid);
-            });
-            assert!(FOO.state() == LocalKeyState::Valid);
+            assert!(FOO.try_with(|_| ()).is_ok());
         }).join().ok().unwrap();
     }
 
@@ -613,7 +517,7 @@ mod tests {
             fn drop(&mut self) {
                 unsafe {
                     HITS += 1;
-                    if K2.state() == LocalKeyState::Destroyed {
+                    if K2.try_with(|_| ()).is_err() {
                         assert_eq!(HITS, 3);
                     } else {
                         if HITS == 1 {
@@ -629,7 +533,7 @@ mod tests {
             fn drop(&mut self) {
                 unsafe {
                     HITS += 1;
-                    assert!(K1.state() != LocalKeyState::Destroyed);
+                    assert!(K1.try_with(|_| ()).is_ok());
                     assert_eq!(HITS, 2);
                     K1.with(|s| *s.get() = Some(S1));
                 }
@@ -648,7 +552,7 @@ mod tests {
 
         impl Drop for S1 {
             fn drop(&mut self) {
-                assert!(K1.state() == LocalKeyState::Destroyed);
+                assert!(K1.try_with(|_| ()).is_err());
             }
         }
 
@@ -672,9 +576,7 @@ mod tests {
             fn drop(&mut self) {
                 let S1(ref tx) = *self;
                 unsafe {
-                    if K2.state() != LocalKeyState::Destroyed {
-                        K2.with(|s| *s.get() = Some(Foo(tx.clone())));
-                    }
+                    let _ = K2.try_with(|s| *s.get() = Some(Foo(tx.clone())));
                 }
             }
         }
diff --git a/ctr-std/src/thread/mod.rs b/ctr-std/src/thread/mod.rs
index ee49bf7..71aee67 100644
--- a/ctr-std/src/thread/mod.rs
+++ b/ctr-std/src/thread/mod.rs
@@ -191,7 +191,7 @@ use time::Duration;
 #[macro_use] mod local;
 
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use self::local::{LocalKey, LocalKeyState, AccessError};
+pub use self::local::{LocalKey, AccessError};
 
 // The types used by the thread_local! macro to access TLS keys. Note that there
 // are two types, the "OS" type and the "fast" type. The OS thread local key
@@ -652,7 +652,7 @@ pub fn panicking() -> bool {
 /// The thread may sleep longer than the duration specified due to scheduling
 /// specifics or platform-dependent functionality.
 ///
-/// # Platform behavior
+/// # Platform-specific behavior
 ///
 /// On Unix platforms this function will not return early due to a
 /// signal being received or a spurious wakeup.
@@ -676,7 +676,7 @@ pub fn sleep_ms(ms: u32) {
 /// The thread may sleep longer than the duration specified due to scheduling
 /// specifics or platform-dependent functionality.
 ///
-/// # Platform behavior
+/// # Platform-specific behavior
 ///
 /// On Unix platforms this function will not return early due to a
 /// signal being received or a spurious wakeup. Platforms which do not support
@@ -837,7 +837,7 @@ pub fn park_timeout_ms(ms: u32) {
 ///
 /// See the [park documentation][park] for more details.
 ///
-/// # Platform behavior
+/// # Platform-specific behavior
 ///
 /// Platforms which do not support nanosecond precision for sleeping will have
 /// `dur` rounded up to the nearest granularity of time they can sleep for.
diff --git a/ctr-std/src/time.rs b/ctr-std/src/time.rs
index 12f2a9b..1215302 100644
--- a/ctr-std/src/time.rs
+++ b/ctr-std/src/time.rs
@@ -49,6 +49,9 @@ pub use core::time::Duration;
 /// allows measuring the duration between two instants (or comparing two
 /// instants).
 ///
+/// The size of an `Instant` struct may vary depending on the target operating
+/// system.
+///
 /// Example:
 ///
 /// ```no_run
@@ -88,6 +91,9 @@ pub struct Instant(time::Instant);
 /// fixed point in time, a `SystemTime` can be converted to a human-readable time,
 /// or perhaps some other string representation.
 ///
+/// The size of a `SystemTime` struct may vary depending on the target operating
+/// system.
+///
 /// [`Instant`]: ../../std/time/struct.Instant.html
 /// [`Result`]: ../../std/result/enum.Result.html
 /// [`Duration`]: ../../std/time/struct.Duration.html
@@ -253,6 +259,29 @@ impl fmt::Debug for Instant {
 }
 
 impl SystemTime {
+    /// An anchor in time which can be used to create new `SystemTime` instances or
+    /// learn about where in time a `SystemTime` lies.
+    ///
+    /// This constant is defined to be "1970-01-01 00:00:00 UTC" on all systems with
+    /// respect to the system clock. Using `duration_since` on an existing
+    /// `SystemTime` instance can tell how far away from this point in time a
+    /// measurement lies, and using `UNIX_EPOCH + duration` can be used to create a
+    /// `SystemTime` instance to represent another fixed point in time.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// #![feature(assoc_unix_epoch)]
+    /// use std::time::SystemTime;
+    ///
+    /// match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
+    ///     Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
+    ///     Err(_) => panic!("SystemTime before UNIX EPOCH!"),
+    /// }
+    /// ```
+    #[unstable(feature = "assoc_unix_epoch", issue = "49502")]
+    pub const UNIX_EPOCH: SystemTime = UNIX_EPOCH;
+
     /// Returns the system time corresponding to "now".
     ///
     /// # Examples