Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 939 insertions, 0 deletions

diff --git a/third_party/rust/either/.cargo-checksum.json b/third_party/rust/either/.cargo-checksum.json
new file mode 100644
index 0000000000..4164f37198
--- /dev/null
+++ b/third_party/rust/either/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"Cargo.toml":"76b9389a7d769eff88be373c17bc7384f8a55e15aea2d8955fffb07cf51ca413","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"7576269ea71f767b99297934c0b2367532690f8c4badc695edf8e04ab6a1e545","README.rst":"3813c794770085af90f88860e71fb8f172472584a4844de6e4a4ad32be084589","src/lib.rs":"5179302c50ad3f20fb54ffaacbbfd2c58a0273f98ae753a3b8a6632f0e954b8a"},"package":"18785c1ba806c258137c937e44ada9ee7e69a37e3c72077542cd2f069d78562a"}
\ No newline at end of file
diff --git a/third_party/rust/either/Cargo.toml b/third_party/rust/either/Cargo.toml
new file mode 100644
index 0000000000..1265ea333a
--- /dev/null
+++ b/third_party/rust/either/Cargo.toml
@@ -0,0 +1,22 @@
+[package]
+name = "either"
+version = "1.1.0"
+authors = ["bluss"]
+
+license = "MIT/Apache-2.0"
+repository = "https://github.com/bluss/either"
+documentation = "https://docs.rs/either/1/"
+
+description = """
+The enum `Either`, with variants `Left` and `Right` and trait implementations including Iterator, Read, Write.
+
+Either has methods that are similar to Option and Result.
+
+Includes convenience macros `try_left!()` and `try_right!()` to use for short-circuiting logic."""
+
+keywords = ["data-structure", "no_std"]
+categories = ["data-structures", "no-std"]
+
+[features]
+default = ["use_std"]
+use_std = []
diff --git a/third_party/rust/either/LICENSE-APACHE b/third_party/rust/either/LICENSE-APACHE
new file mode 100644
index 0000000000..16fe87b06e
--- /dev/null
+++ b/third_party/rust/either/LICENSE-APACHE
@@ -0,0 +1,201 @@
+                              Apache License
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+
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diff --git a/third_party/rust/either/LICENSE-MIT b/third_party/rust/either/LICENSE-MIT
new file mode 100644
index 0000000000..9203baa055
--- /dev/null
+++ b/third_party/rust/either/LICENSE-MIT
@@ -0,0 +1,25 @@
+Copyright (c) 2015
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/third_party/rust/either/README.rst b/third_party/rust/either/README.rst
new file mode 100644
index 0000000000..ddd17ea308
--- /dev/null
+++ b/third_party/rust/either/README.rst
@@ -0,0 +1,88 @@
+
+Either
+======
+
+The enum ``Either`` with variants ``Left`` and ``Right`` and trait
+implementations including Iterator, Read, Write.
+
+Either has methods that are similar to Option and Result.
+
+Includes convenience macros ``try_left!()`` and ``try_right!()`` to use for
+short-circuiting logic.
+
+Please read the `API documentation here`__
+
+__ https://docs.rs/either/
+
+|build_status|_ |crates|_
+
+.. |build_status| image:: https://travis-ci.org/bluss/either.svg?branch=master
+.. _build_status: https://travis-ci.org/bluss/either
+
+.. |crates| image:: http://meritbadge.herokuapp.com/either
+.. _crates: https://crates.io/crates/either
+
+How to use with cargo::
+
+    [dependencies]
+    either = "1.0"
+
+
+Recent Changes
+--------------
+
+- 1.1.0
+
+  - Add methods ``left_and_then``, ``right_and_then`` by @rampantmonkey
+  - Include license files in the repository and released crate
+
+- 1.0.3
+
+  - Add crate categories
+
+- 1.0.2
+
+  - Forward more ``Iterator`` methods
+  - Implement ``Extend`` for ``Either<L, R>`` if ``L, R`` do.
+
+- 1.0.1
+
+  - Fix ``Iterator`` impl for ``Either`` to forward ``.fold()``.
+
+- 1.0.0
+
+  - Add default crate feature ``use_std`` so that you can opt out of linking to
+    std.
+
+- 0.1.7
+
+  - Add methods ``.map_left()``, ``.map_right()`` and ``.either()``.
+  - Add more documentation
+
+- 0.1.3
+
+  - Implement Display, Error
+
+- 0.1.2
+
+  - Add macros ``try_left!`` and ``try_right!``.
+
+- 0.1.1
+
+  - Implement Deref, DerefMut
+
+- 0.1.0
+
+  - Initial release
+  - Support Iterator, Read, Write
+
+License
+-------
+
+Dual-licensed to be compatible with the Rust project.
+
+Licensed under the Apache License, Version 2.0
+http://www.apache.org/licenses/LICENSE-2.0 or the MIT license
+http://opensource.org/licenses/MIT, at your
+option. This file may not be copied, modified, or distributed
+except according to those terms.
diff --git a/third_party/rust/either/src/lib.rs b/third_party/rust/either/src/lib.rs
new file mode 100644
index 0000000000..a28340782f
--- /dev/null
+++ b/third_party/rust/either/src/lib.rs
@@ -0,0 +1,602 @@
+//! The enum [**Either**](enum.Either.html).
+//!
+//! **Crate features:**
+//!
+//! * `"use_std"`
+//! Enabled by default. Disable to make the library `#![no_std]`.
+//!
+
+#![doc(html_root_url = "https://docs.rs/either/1/")]
+#![cfg_attr(all(not(test), not(feature = "use_std")), no_std)]
+#[cfg(all(not(test), not(feature = "use_std")))]
+extern crate core as std;
+
+use std::convert::{AsRef, AsMut};
+use std::fmt;
+use std::iter;
+use std::ops::Deref;
+use std::ops::DerefMut;
+#[cfg(any(test, feature = "use_std"))]
+use std::io::{self, Write, Read, BufRead};
+#[cfg(any(test, feature = "use_std"))]
+use std::error::Error;
+
+pub use Either::{Left, Right};
+
+/// `Either` represents an alternative holding one value out of
+/// either of the two possible values.
+///
+/// `Either` is a general purpose sum type of two parts. For representing
+/// success or error, use the regular `Result<T, E>` instead.
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub enum Either<L, R> {
+    /// A value of type `L`.
+    Left(L),
+    /// A value of type `R`.
+    Right(R),
+}
+
+macro_rules! either {
+    ($value:expr, $pattern:pat => $result:expr) => (
+        match $value {
+            Either::Left($pattern) => $result,
+            Either::Right($pattern) => $result,
+        }
+    )
+}
+
+/// Macro for unwrapping the left side of an `Either`, which fails early
+/// with the opposite side. Can only be used in functions that return
+/// `Either` because of the early return of `Right` that it provides.
+///
+/// See also `try_right!` for its dual, which applies the same just to the
+/// right side.
+///
+/// # Example
+///
+/// ```
+/// #[macro_use] extern crate either;
+/// use either::{Either, Left, Right};
+///
+/// fn twice(wrapper: Either<u32, &str>) -> Either<u32, &str> {
+///     let value = try_left!(wrapper);
+///     Left(value * 2)
+/// }
+///
+/// fn main() {
+///     assert_eq!(twice(Left(2)), Left(4));
+///     assert_eq!(twice(Right("ups")), Right("ups"));
+/// }
+/// ```
+#[macro_export]
+macro_rules! try_left {
+    ($expr:expr) => (
+        match $expr {
+            $crate::Left(val) => val,
+            $crate::Right(err) => return $crate::Right(::std::convert::From::from(err))
+        }
+    )
+}
+
+/// Dual to `try_left!`, see its documentation for more information.
+#[macro_export]
+macro_rules! try_right {
+    ($expr:expr) => (
+        match $expr {
+            $crate::Left(err) => return $crate::Left(::std::convert::From::from(err)),
+            $crate::Right(val) => val
+        }
+    )
+}
+
+impl<L, R> Either<L, R> {
+    /// Return true if the value is the `Left` variant.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let values = [Left(1), Right("the right value")];
+    /// assert_eq!(values[0].is_left(), true);
+    /// assert_eq!(values[1].is_left(), false);
+    /// ```
+    pub fn is_left(&self) -> bool {
+        match *self {
+            Left(_) => true,
+            Right(_) => false,
+        }
+    }
+
+    /// Return true if the value is the `Right` variant.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let values = [Left(1), Right("the right value")];
+    /// assert_eq!(values[0].is_right(), false);
+    /// assert_eq!(values[1].is_right(), true);
+    /// ```
+    pub fn is_right(&self) -> bool {
+        !self.is_left()
+    }
+
+    /// Convert the left side of `Either<L, R>` to an `Option<L>`.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, ()> = Left("some value");
+    /// assert_eq!(left.left(),  Some("some value"));
+    ///
+    /// let right: Either<(), _> = Right(321);
+    /// assert_eq!(right.left(), None);
+    /// ```
+    pub fn left(self) -> Option<L> {
+        match self {
+            Left(l) => Some(l),
+            Right(_) => None,
+        }
+    }
+
+    /// Convert the right side of `Either<L, R>` to an `Option<R>`.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, ()> = Left("some value");
+    /// assert_eq!(left.right(),  None);
+    ///
+    /// let right: Either<(), _> = Right(321);
+    /// assert_eq!(right.right(), Some(321));
+    /// ```
+    pub fn right(self) -> Option<R> {
+        match self {
+            Left(_) => None,
+            Right(r) => Some(r),
+        }
+    }
+
+    /// Convert `&Either<L, R>` to `Either<&L, &R>`.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, ()> = Left("some value");
+    /// assert_eq!(left.as_ref(), Left(&"some value"));
+    ///
+    /// let right: Either<(), _> = Right("some value");
+    /// assert_eq!(right.as_ref(), Right(&"some value"));
+    /// ```
+    pub fn as_ref(&self) -> Either<&L, &R> {
+        match *self {
+            Left(ref inner) => Left(inner),
+            Right(ref inner) => Right(inner),
+        }
+    }
+
+    /// Convert `&mut Either<L, R>` to `Either<&mut L, &mut R>`.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// fn mutate_left(value: &mut Either<u32, u32>) {
+    ///     if let Some(l) = value.as_mut().left() {
+    ///         *l = 999;
+    ///     }
+    /// }
+    ///
+    /// let mut left = Left(123);
+    /// let mut right = Right(123);
+    /// mutate_left(&mut left);
+    /// mutate_left(&mut right);
+    /// assert_eq!(left, Left(999));
+    /// assert_eq!(right, Right(123));
+    /// ```
+    pub fn as_mut(&mut self) -> Either<&mut L, &mut R> {
+        match *self {
+            Left(ref mut inner) => Left(inner),
+            Right(ref mut inner) => Right(inner),
+        }
+    }
+
+    /// Convert `Either<L, R>` to `Either<R, L>`.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, ()> = Left(123);
+    /// assert_eq!(left.flip(), Right(123));
+    ///
+    /// let right: Either<(), _> = Right("some value");
+    /// assert_eq!(right.flip(), Left("some value"));
+    /// ```
+    pub fn flip(self) -> Either<R, L> {
+        match self {
+            Left(l) => Right(l),
+            Right(r) => Left(r),
+        }
+    }
+
+    /// Apply the function `f` on the value in the `Left` variant if it is present rewrapping the
+    /// result in `Left`.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, u32> = Left(123);
+    /// assert_eq!(left.map_left(|x| x * 2), Left(246));
+    ///
+    /// let right: Either<u32, _> = Right(123);
+    /// assert_eq!(right.map_left(|x| x * 2), Right(123));
+    /// ```
+    pub fn map_left<F, M>(self, f: F) -> Either<M, R>
+        where F: FnOnce(L) -> M
+    {
+        match self {
+            Left(l) => Left(f(l)),
+            Right(r) => Right(r),
+        }
+    }
+
+    /// Apply the function `f` on the value in the `Right` variant if it is present rewrapping the
+    /// result in `Right`.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, u32> = Left(123);
+    /// assert_eq!(left.map_right(|x| x * 2), Left(123));
+    ///
+    /// let right: Either<u32, _> = Right(123);
+    /// assert_eq!(right.map_right(|x| x * 2), Right(246));
+    /// ```
+    pub fn map_right<F, S>(self, f: F) -> Either<L, S>
+        where F: FnOnce(R) -> S
+    {
+        match self {
+            Left(l) => Left(l),
+            Right(r) => Right(f(r)),
+        }
+    }
+
+    /// Apply one of two functions depending on contents, unifying their result. If the value is
+    /// `Left(L)` then the first function `f` is applied; if it is `Right(R)` then the second
+    /// function `g` is applied.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// fn square(n: u32) -> i32 { (n * n) as i32 }
+    /// fn negate(n: i32) -> i32 { -n }
+    ///
+    /// let left: Either<u32, i32> = Left(4);
+    /// assert_eq!(left.either(square, negate), 16);
+    ///
+    /// let right: Either<u32, i32> = Right(-4);
+    /// assert_eq!(right.either(square, negate), 4);
+    /// ```
+    pub fn either<F, G, T>(self, f: F, g: G) -> T
+      where F: FnOnce(L) -> T,
+            G: FnOnce(R) -> T
+    {
+        match self {
+            Left(l) => f(l),
+            Right(r) => g(r),
+        }
+    }
+
+    /// Apply the function `f` on the value in the `Left` variant if it is present.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, u32> = Left(123);
+    /// assert_eq!(left.left_and_then::<_,()>(|x| Right(x * 2)), Right(246));
+    ///
+    /// let right: Either<u32, _> = Right(123);
+    /// assert_eq!(right.left_and_then(|x| Right::<(), _>(x * 2)), Right(123));
+    /// ```
+    pub fn left_and_then<F, S>(self, f: F) -> Either<S, R>
+        where F: FnOnce(L) -> Either<S, R>
+    {
+        match self {
+            Left(l) => f(l),
+            Right(r) => Right(r),
+        }
+    }
+
+    /// Apply the function `f` on the value in the `Right` variant if it is present.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, u32> = Left(123);
+    /// assert_eq!(left.right_and_then(|x| Right(x * 2)), Left(123));
+    ///
+    /// let right: Either<u32, _> = Right(123);
+    /// assert_eq!(right.right_and_then(|x| Right(x * 2)), Right(246));
+    /// ```
+    pub fn right_and_then<F, S>(self, f: F) -> Either<L, S>
+        where F: FnOnce(R) -> Either<L, S>
+    {
+        match self {
+            Left(l) => Left(l),
+            Right(r) => f(r),
+        }
+    }
+}
+
+/// Convert from `Result` to `Either` with `Ok => Right` and `Err => Left`.
+impl<L, R> From<Result<R, L>> for Either<L, R> {
+    fn from(r: Result<R, L>) -> Self {
+        match r {
+            Err(e) => Left(e),
+            Ok(o) => Right(o),
+        }
+    }
+}
+
+/// Convert from `Either` to `Result` with `Right => Ok` and `Left => Err`.
+impl<L, R> Into<Result<R, L>> for Either<L, R> {
+    fn into(self) -> Result<R, L> {
+        match self {
+            Left(l) => Err(l),
+            Right(r) => Ok(r),
+        }
+    }
+}
+
+impl<L, R, A> Extend<A> for Either<L, R>
+    where L: Extend<A>, R: Extend<A>
+{
+    fn extend<T>(&mut self, iter: T)
+        where T: IntoIterator<Item=A>
+    {
+        either!(*self, ref mut inner => inner.extend(iter))
+    }
+}
+
+/// `Either<L, R>` is an iterator if both `L` and `R` are iterators.
+impl<L, R> Iterator for Either<L, R>
+    where L: Iterator, R: Iterator<Item=L::Item>
+{
+    type Item = L::Item;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        either!(*self, ref mut inner => inner.next())
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        either!(*self, ref inner => inner.size_hint())
+    }
+
+    fn fold<Acc, G>(self, init: Acc, f: G) -> Acc
+        where G: FnMut(Acc, Self::Item) -> Acc,
+    {
+        either!(self, inner => inner.fold(init, f))
+    }
+
+    fn count(self) -> usize {
+        either!(self, inner => inner.count())
+    }
+
+    fn last(self) -> Option<Self::Item> {
+        either!(self, inner => inner.last())
+    }
+
+    fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        either!(*self, ref mut inner => inner.nth(n))
+    }
+
+    fn collect<B>(self) -> B
+        where B: iter::FromIterator<Self::Item>
+    {
+        either!(self, inner => inner.collect())
+    }
+
+    fn all<F>(&mut self, f: F) -> bool
+        where F: FnMut(Self::Item) -> bool
+    {
+        either!(*self, ref mut inner => inner.all(f))
+    }
+}
+
+impl<L, R> DoubleEndedIterator for Either<L, R>
+    where L: DoubleEndedIterator, R: DoubleEndedIterator<Item=L::Item>
+{
+    fn next_back(&mut self) -> Option<Self::Item> {
+        either!(*self, ref mut inner => inner.next_back())
+    }
+}
+
+impl<L, R> ExactSizeIterator for Either<L, R>
+    where L: ExactSizeIterator, R: ExactSizeIterator<Item=L::Item>
+{
+}
+
+#[cfg(any(test, feature = "use_std"))]
+/// `Either<L, R>` implements `Read` if both `L` and `R` do.
+///
+/// Requires crate feature `"use_std"`
+impl<L, R> Read for Either<L, R>
+    where L: Read, R: Read
+{
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        either!(*self, ref mut inner => inner.read(buf))
+    }
+
+    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
+        either!(*self, ref mut inner => inner.read_to_end(buf))
+    }
+}
+
+#[cfg(any(test, feature = "use_std"))]
+/// Requires crate feature `"use_std"`
+impl<L, R> BufRead for Either<L, R>
+    where L: BufRead, R: BufRead
+{
+    fn fill_buf(&mut self) -> io::Result<&[u8]> {
+        either!(*self, ref mut inner => inner.fill_buf())
+    }
+
+    fn consume(&mut self, amt: usize) {
+        either!(*self, ref mut inner => inner.consume(amt))
+    }
+}
+
+#[cfg(any(test, feature = "use_std"))]
+/// `Either<L, R>` implements `Write` if both `L` and `R` do.
+///
+/// Requires crate feature `"use_std"`
+impl<L, R> Write for Either<L, R>
+    where L: Write, R: Write
+{
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        either!(*self, ref mut inner => inner.write(buf))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        either!(*self, ref mut inner => inner.flush())
+    }
+}
+
+impl<L, R, Target> AsRef<Target> for Either<L, R>
+    where L: AsRef<Target>, R: AsRef<Target>
+{
+    fn as_ref(&self) -> &Target {
+        either!(*self, ref inner => inner.as_ref())
+    }
+}
+
+impl<L, R, Target> AsMut<Target> for Either<L, R>
+    where L: AsMut<Target>, R: AsMut<Target>
+{
+    fn as_mut(&mut self) -> &mut Target {
+        either!(*self, ref mut inner => inner.as_mut())
+    }
+}
+
+impl<L, R> Deref for Either<L, R>
+    where L: Deref, R: Deref<Target=L::Target>
+{
+    type Target = L::Target;
+
+    fn deref(&self) -> &Self::Target {
+        either!(*self, ref inner => &*inner)
+    }
+}
+
+impl<L, R> DerefMut for Either<L, R>
+    where L: DerefMut, R: DerefMut<Target=L::Target>
+{
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        either!(*self, ref mut inner => &mut *inner)
+    }
+}
+
+#[cfg(any(test, feature = "use_std"))]
+/// `Either` implements `Error` if *both* `L` and `R` implement it.
+impl<L, R> Error for Either<L, R>
+    where L: Error, R: Error
+{
+    fn description(&self) -> &str {
+        either!(*self, ref inner => inner.description())
+    }
+
+    fn cause(&self) -> Option<&Error> {
+        either!(*self, ref inner => inner.cause())
+    }
+}
+
+impl<L, R> fmt::Display for Either<L, R>
+    where L: fmt::Display, R: fmt::Display
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        either!(*self, ref inner => inner.fmt(f))
+    }
+}
+
+#[test]
+fn basic() {
+    let mut e = Left(2);
+    let r = Right(2);
+    assert_eq!(e, Left(2));
+    e = r;
+    assert_eq!(e, Right(2));
+    assert_eq!(e.left(), None);
+    assert_eq!(e.right(), Some(2));
+    assert_eq!(e.as_ref().right(), Some(&2));
+    assert_eq!(e.as_mut().right(), Some(&mut 2));
+}
+
+#[test]
+fn macros() {
+    fn a() -> Either<u32, u32> {
+        let x: u32 = try_left!(Right(1337u32));
+        Left(x * 2)
+    }
+    assert_eq!(a(), Right(1337));
+
+    fn b() -> Either<String, &'static str> {
+        Right(try_right!(Left("foo bar")))
+    }
+    assert_eq!(b(), Left(String::from("foo bar")));
+}
+
+#[test]
+fn deref() {
+    fn is_str(_: &str) {}
+    let value: Either<String, &str> = Left(String::from("test"));
+    is_str(&*value);
+}
+
+#[test]
+fn iter() {
+    let x = 3;
+    let mut iter = match x {
+        1...3 => Left(0..10),
+        _ => Right(17..),
+    };
+
+    assert_eq!(iter.next(), Some(0));
+    assert_eq!(iter.count(), 9);
+}
+
+#[test]
+fn read_write() {
+    use std::io;
+
+    let use_stdio = false;
+    let mockdata = [0xff; 256];
+
+    let mut reader = if use_stdio {
+        Left(io::stdin())
+    } else {
+        Right(&mockdata[..])
+    };
+
+    let mut buf = [0u8; 16];
+    assert_eq!(reader.read(&mut buf).unwrap(), buf.len());
+    assert_eq!(&buf, &mockdata[..buf.len()]);
+
+    let mut mockbuf = [0u8; 256];
+    let mut writer = if use_stdio {
+        Left(io::stdout())
+    } else {
+        Right(&mut mockbuf[..])
+    };
+
+    let buf = [1u8; 16];
+    assert_eq!(writer.write(&buf).unwrap(), buf.len());
+}
+
+#[test]
+fn error() {
+    let invalid_utf8 = b"\xff";
+    let res = || -> Result<_, Either<_, _>> {
+        try!(::std::str::from_utf8(invalid_utf8).map_err(Left));
+        try!("x".parse::<i32>().map_err(Right));
+        Ok(())
+    }();
+    assert!(res.is_err());
+    res.unwrap_err().description(); // make sure this can be called
+}