Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 1262 insertions, 0 deletions

diff --git a/third_party/rust/quick-error/src/lib.rs b/third_party/rust/quick-error/src/lib.rs
new file mode 100644
index 0000000000..17fc455d46
--- /dev/null
+++ b/third_party/rust/quick-error/src/lib.rs
@@ -0,0 +1,1262 @@
+#![warn(missing_docs)]
+//! A macro which makes errors easy to write
+//!
+//! Minimum type is like this:
+//!
+//! ```rust
+//! #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//!
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         Variant1 {}
+//!     }
+//! }
+//! ```
+//! Both ``pub`` and non-public types may be declared, and all meta attributes
+//! (such as ``#[derive(Debug)]``) are forwarded as is. The `Debug` must be
+//! implemented (but you may do that yourself if you like). The documentation
+//! comments ``/// something`` (as well as other meta attrbiutes) on variants
+//! are allowed.
+//!
+//! # Allowed Syntax
+//!
+//! You may add arbitrary parameters to any struct variant:
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//! #
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         /// IO Error
+//!         Io(err: std::io::Error) {}
+//!         /// Utf8 Error
+//!         Utf8(err: std::str::Utf8Error) {}
+//!     }
+//! }
+//! ```
+//!
+//! Note unlike in normal Enum declarations you declare names of fields (which
+//! are omitted from type). How they can be used is outlined below.
+//!
+//! Now you might have noticed trailing braces `{}`. They are used to define
+//! implementations. By default:
+//!
+//! * `Error::cause()` returns None (even if type wraps some value)
+//! * `Display` outputs debug representation
+//! * No `From` implementations are defined
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//! #
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         Io(err: std::io::Error) {
+//!             display("{}", err)
+//!         }
+//!         Utf8(err: std::str::Utf8Error) {
+//!             display("utf8 error")
+//!         }
+//!     }
+//! }
+//! ```
+//!
+//! To change `cause` method to return some error, add `cause(value)`, for
+//! example:
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//! #
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         Io(err: std::io::Error) {
+//!             cause(err)
+//!         }
+//!         Utf8(err: std::str::Utf8Error) {
+//!             display("utf8 error")
+//!         }
+//!         Other(err: Box<std::error::Error>) {
+//!             cause(&**err)
+//!         }
+//!     }
+//! }
+//! ```
+//! Note you don't need to wrap value in `Some`, its implicit. In case you want
+//! `None` returned just omit the `cause`. You can't return `None`
+//! conditionally.
+//!
+//! To change how each clause is `Display`ed add `display(pattern,..args)`,
+//! for example:
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//! #
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         Io(err: std::io::Error) {
+//!             display("I/O error: {}", err)
+//!         }
+//!         Utf8(err: std::str::Utf8Error) {
+//!             display("Utf8 error, valid up to {}", err.valid_up_to())
+//!         }
+//!     }
+//! }
+//! ```
+//!
+//! If you need a reference to the error when `Display`ing, you can instead use
+//! `display(x) -> (pattern, ..args)`, where `x` sets the name of the reference.
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//! #
+//! use std::error::Error; // put methods like `source()` of this trait into scope
+//!
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         Io(err: std::io::Error) {
+//!             display(x) -> ("I/O: {}", err)
+//!         }
+//!         Utf8(err: std::str::Utf8Error) {
+//!             display(self_) -> ("UTF-8 error. Valid up to {}", err.valid_up_to())
+//!         }
+//!     }
+//! }
+//! ```
+//!
+//! To convert to the type from any other, use one of the three forms of
+//! `from` clause.
+//!
+//! For example, to convert simple wrapper use bare `from()`:
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//! #
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         Io(err: std::io::Error) {
+//!             from()
+//!         }
+//!     }
+//! }
+//! ```
+//!
+//! This implements ``From<io::Error>``.
+//!
+//! To convert to singleton enumeration type (discarding the value), use
+//! the `from(type)` form:
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//! #
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         FormatError {
+//!             from(std::fmt::Error)
+//!         }
+//!     }
+//! }
+//! ```
+//!
+//! And the most powerful form is `from(var: type) -> (arguments...)`. It
+//! might be used to convert to type with multiple arguments or for arbitrary
+//! value conversions:
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//! #
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum SomeError {
+//!         FailedOperation(s: &'static str, errno: i32) {
+//!             from(errno: i32) -> ("os error", errno)
+//!             from(e: std::io::Error) -> ("io error", e.raw_os_error().unwrap())
+//!         }
+//!         /// Converts from both kinds of utf8 errors
+//!         Utf8(err: std::str::Utf8Error) {
+//!             from()
+//!             from(err: std::string::FromUtf8Error) -> (err.utf8_error())
+//!         }
+//!     }
+//! }
+//! ```
+//! # Context
+//!
+//! Since quick-error 1.1 we also have a `context` declaration, which is
+//! similar to (the longest form of) `from`, but allows adding some context to
+//! the error. We need a longer example to demonstrate this:
+//!
+//! ```rust
+//! # #[macro_use] extern crate quick_error;
+//! # use std::io;
+//! # use std::fs::File;
+//! # use std::path::{Path, PathBuf};
+//! #
+//! use quick_error::ResultExt;
+//!
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum Error {
+//!         File(filename: PathBuf, err: io::Error) {
+//!             context(path: &'a Path, err: io::Error)
+//!                 -> (path.to_path_buf(), err)
+//!         }
+//!     }
+//! }
+//!
+//! fn openfile(path: &Path) -> Result<(), Error> {
+//!     try!(File::open(path).context(path));
+//!
+//!     // If we didn't have context, the line above would be written as;
+//!     //
+//!     // try!(File::open(path)
+//!     //     .map_err(|err| Error::File(path.to_path_buf(), err)));
+//!
+//!     Ok(())
+//! }
+//!
+//! # fn main() {
+//! #     openfile(Path::new("/etc/somefile")).ok();
+//! # }
+//! ```
+//!
+//! Each `context(a: A, b: B)` clause implements
+//! `From<Context<A, B>> for Error`. Which means multiple `context` clauses
+//! are a subject to the normal coherence rules. Unfortunately, we can't
+//! provide full support of generics for the context, but you may either use a
+//! lifetime `'a` for references or `AsRef<Type>` (the latter means `A:
+//! AsRef<Type>`, and `Type` must be concrete). It's also occasionally useful
+//! to use a tuple as a type of the first argument.
+//!
+//! You also need to `use quick_error::ResultExt` extension trait to get
+//! working `.context()` method.
+//!
+//! More info on context in [this article](http://bit.ly/1PsuxDt).
+//!
+//! All forms of `from`, `display`, `cause`, and `context`
+//! clauses can be combined and put in arbitrary order. Only `from` and
+//! `context` can be used multiple times in single variant of enumeration.
+//! Docstrings are also okay.  Empty braces can be omitted as of quick_error
+//! 0.1.3.
+//!
+//! # Private Enums
+//!
+//! Since quick-error 1.2.0 we  have a way to make a private enum that is
+//! wrapped by public structure:
+//!
+//! ```rust
+//! #[macro_use] extern crate quick_error;
+//! # fn main() {}
+//!
+//! quick_error! {
+//!     #[derive(Debug)]
+//!     pub enum PubError wraps ErrorEnum {
+//!         Variant1 {}
+//!     }
+//! }
+//! ```
+//!
+//! This generates data structures like this
+//!
+//! ```rust
+//!
+//! pub struct PubError(ErrorEnum);
+//!
+//! enum ErrorEnum {
+//!     Variant1,
+//! }
+//!
+//! ```
+//!
+//! Which in turn allows you to export just `PubError` in your crate and keep
+//! actual enumeration private to the crate. This is useful to keep backwards
+//! compatibility for error types. Currently there is no shorcuts to define
+//! error constructors for the inner type, but we consider adding some in
+//! future versions.
+//!
+//! It's possible to declare internal enum as public too.
+//!
+//!
+
+
+/// Main macro that does all the work
+#[macro_export]
+macro_rules! quick_error {
+
+    (   $(#[$meta:meta])*
+        pub enum $name:ident { $($chunks:tt)* }
+    ) => {
+        quick_error!(SORT [pub enum $name $(#[$meta])* ]
+            items [] buf []
+            queue [ $($chunks)* ]);
+    };
+    (   $(#[$meta:meta])*
+        enum $name:ident { $($chunks:tt)* }
+    ) => {
+        quick_error!(SORT [enum $name $(#[$meta])* ]
+            items [] buf []
+            queue [ $($chunks)* ]);
+    };
+
+    (   $(#[$meta:meta])*
+        pub enum $name:ident wraps $enum_name:ident { $($chunks:tt)* }
+    ) => {
+        quick_error!(WRAPPER $enum_name [ pub struct ] $name $(#[$meta])*);
+        quick_error!(SORT [enum $enum_name $(#[$meta])* ]
+            items [] buf []
+            queue [ $($chunks)* ]);
+    };
+
+    (   $(#[$meta:meta])*
+        pub enum $name:ident wraps pub $enum_name:ident { $($chunks:tt)* }
+    ) => {
+        quick_error!(WRAPPER $enum_name [ pub struct ] $name $(#[$meta])*);
+        quick_error!(SORT [pub enum $enum_name $(#[$meta])* ]
+            items [] buf []
+            queue [ $($chunks)* ]);
+    };
+    (   $(#[$meta:meta])*
+        enum $name:ident wraps $enum_name:ident { $($chunks:tt)* }
+    ) => {
+        quick_error!(WRAPPER $enum_name [ struct ] $name $(#[$meta])*);
+        quick_error!(SORT [enum $enum_name $(#[$meta])* ]
+            items [] buf []
+            queue [ $($chunks)* ]);
+    };
+
+    (   $(#[$meta:meta])*
+        enum $name:ident wraps pub $enum_name:ident { $($chunks:tt)* }
+    ) => {
+        quick_error!(WRAPPER $enum_name [ struct ] $name $(#[$meta])*);
+        quick_error!(SORT [pub enum $enum_name $(#[$meta])* ]
+            items [] buf []
+            queue [ $($chunks)* ]);
+    };
+
+
+    (
+        WRAPPER $internal:ident [ $($strdef:tt)* ] $strname:ident
+        $(#[$meta:meta])*
+    ) => {
+        $(#[$meta])*
+        $($strdef)* $strname ( $internal );
+
+        impl ::std::fmt::Display for $strname {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter)
+                -> ::std::fmt::Result
+            {
+                ::std::fmt::Display::fmt(&self.0, f)
+            }
+        }
+
+        impl From<$internal> for $strname {
+            fn from(err: $internal) -> Self {
+                $strname(err)
+            }
+        }
+
+        impl ::std::error::Error for $strname {
+            #[allow(deprecated)]
+            fn cause(&self) -> Option<&::std::error::Error> {
+                self.0.cause()
+            }
+        }
+    };
+
+    // Queue is empty, can do the work
+    (SORT [enum $name:ident $( #[$meta:meta] )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [ ]
+        queue [ ]
+    ) => {
+        quick_error!(ENUM_DEFINITION [enum $name $( #[$meta] )*]
+            body []
+            queue [$($( #[$imeta] )*
+                      => $iitem: $imode [$( $ivar: $ityp ),*] )*]
+        );
+        quick_error!(IMPLEMENTATIONS $name {$(
+           $iitem: $imode [$(#[$imeta])*] [$( $ivar: $ityp ),*] {$( $ifuncs )*}
+           )*});
+        $(
+            quick_error!(ERROR_CHECK $imode $($ifuncs)*);
+        )*
+    };
+    (SORT [pub enum $name:ident $( #[$meta:meta] )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [ ]
+        queue [ ]
+    ) => {
+        quick_error!(ENUM_DEFINITION [pub enum $name $( #[$meta] )*]
+            body []
+            queue [$($( #[$imeta] )*
+                      => $iitem: $imode [$( $ivar: $ityp ),*] )*]
+        );
+        quick_error!(IMPLEMENTATIONS $name {$(
+           $iitem: $imode [$(#[$imeta])*] [$( $ivar: $ityp ),*] {$( $ifuncs )*}
+           )*});
+        $(
+            quick_error!(ERROR_CHECK $imode $($ifuncs)*);
+        )*
+    };
+    // Add meta to buffer
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )*]
+        queue [ #[$qmeta:meta] $( $tail:tt )*]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            items [$( $(#[$imeta])* => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*]
+            buf [$( #[$bmeta] )* #[$qmeta] ]
+            queue [$( $tail )*]);
+    };
+    // Add ident to buffer
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )*]
+        queue [ $qitem:ident $( $tail:tt )*]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            items [$( $(#[$imeta])*
+                      => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*]
+            buf [$(#[$bmeta])* => $qitem : UNIT [ ] ]
+            queue [$( $tail )*]);
+    };
+    // Flush buffer on meta after ident
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )*
+            => $bitem:ident: $bmode:tt [$( $bvar:ident: $btyp:ty ),*] ]
+        queue [ #[$qmeta:meta] $( $tail:tt )*]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            enum [$( $(#[$emeta])* => $eitem $(( $($etyp),* ))* )*
+                     $(#[$bmeta])* => $bitem: $bmode $(( $($btyp),* ))*]
+            items [$($( #[$imeta:meta] )*
+                      => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*
+                     $bitem: $bmode [$( $bvar:$btyp ),*] {} ]
+            buf [ #[$qmeta] ]
+            queue [$( $tail )*]);
+    };
+    // Add tuple enum-variant
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )* => $bitem:ident: UNIT [ ] ]
+        queue [($( $qvar:ident: $qtyp:ty ),+) $( $tail:tt )*]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            items [$( $(#[$imeta])* => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*]
+            buf [$( #[$bmeta] )* => $bitem: TUPLE [$( $qvar:$qtyp ),*] ]
+            queue [$( $tail )*]
+        );
+    };
+    // Add struct enum-variant - e.g. { descr: &'static str }
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )* => $bitem:ident: UNIT [ ] ]
+        queue [{ $( $qvar:ident: $qtyp:ty ),+} $( $tail:tt )*]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            items [$( $(#[$imeta])* => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*]
+            buf [$( #[$bmeta] )* => $bitem: STRUCT [$( $qvar:$qtyp ),*] ]
+            queue [$( $tail )*]);
+    };
+    // Add struct enum-variant, with excess comma - e.g. { descr: &'static str, }
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )* => $bitem:ident: UNIT [ ] ]
+        queue [{$( $qvar:ident: $qtyp:ty ),+ ,} $( $tail:tt )*]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            items [$( $(#[$imeta])* => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*]
+            buf [$( #[$bmeta] )* => $bitem: STRUCT [$( $qvar:$qtyp ),*] ]
+            queue [$( $tail )*]);
+    };
+    // Add braces and flush always on braces
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )*
+                 => $bitem:ident: $bmode:tt [$( $bvar:ident: $btyp:ty ),*] ]
+        queue [ {$( $qfuncs:tt )*} $( $tail:tt )*]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            items [$( $(#[$imeta])* => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*
+                      $(#[$bmeta])* => $bitem: $bmode [$( $bvar:$btyp ),*] {$( $qfuncs )*} ]
+            buf [ ]
+            queue [$( $tail )*]);
+    };
+    // Flush buffer on double ident
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )*
+                 => $bitem:ident: $bmode:tt [$( $bvar:ident: $btyp:ty ),*] ]
+        queue [ $qitem:ident $( $tail:tt )*]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            items [$( $(#[$imeta])* => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*
+                     $(#[$bmeta])* => $bitem: $bmode [$( $bvar:$btyp ),*] {} ]
+            buf [ => $qitem : UNIT [ ] ]
+            queue [$( $tail )*]);
+    };
+    // Flush buffer on end
+    (SORT [$( $def:tt )*]
+        items [$($( #[$imeta:meta] )*
+                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
+                                {$( $ifuncs:tt )*} )* ]
+        buf [$( #[$bmeta:meta] )*
+            => $bitem:ident: $bmode:tt [$( $bvar:ident: $btyp:ty ),*] ]
+        queue [ ]
+    ) => {
+        quick_error!(SORT [$( $def )*]
+            items [$( $(#[$imeta])* => $iitem: $imode [$( $ivar:$ityp ),*] {$( $ifuncs )*} )*
+                     $(#[$bmeta])* => $bitem: $bmode [$( $bvar:$btyp ),*] {} ]
+            buf [ ]
+            queue [ ]);
+    };
+    // Public enum (Queue Empty)
+    (ENUM_DEFINITION [pub enum $name:ident $( #[$meta:meta] )*]
+        body [$($( #[$imeta:meta] )*
+            => $iitem:ident ($(($( $ttyp:ty ),+))*) {$({$( $svar:ident: $styp:ty ),*})*} )* ]
+        queue [ ]
+    ) => {
+        #[allow(unknown_lints)]  // no unused_doc_comments in older rust
+        #[allow(renamed_and_removed_lints)]
+        #[allow(unused_doc_comment)]
+        #[allow(unused_doc_comments)]
+        $(#[$meta])*
+        pub enum $name {
+            $(
+                $(#[$imeta])*
+                $iitem $(($( $ttyp ),*))* $({$( $svar: $styp ),*})*,
+            )*
+        }
+    };
+    // Private enum (Queue Empty)
+    (ENUM_DEFINITION [enum $name:ident $( #[$meta:meta] )*]
+        body [$($( #[$imeta:meta] )*
+            => $iitem:ident ($(($( $ttyp:ty ),+))*) {$({$( $svar:ident: $styp:ty ),*})*} )* ]
+        queue [ ]
+    ) => {
+        #[allow(unknown_lints)]  // no unused_doc_comments in older rust
+        #[allow(renamed_and_removed_lints)]
+        #[allow(unused_doc_comment)]
+        #[allow(unused_doc_comments)]
+        $(#[$meta])*
+        enum $name {
+            $(
+                $(#[$imeta])*
+                $iitem $(($( $ttyp ),*))* $({$( $svar: $styp ),*})*,
+            )*
+        }
+    };
+    // Unit variant
+    (ENUM_DEFINITION [$( $def:tt )*]
+        body [$($( #[$imeta:meta] )*
+            => $iitem:ident ($(($( $ttyp:ty ),+))*) {$({$( $svar:ident: $styp:ty ),*})*} )* ]
+        queue [$( #[$qmeta:meta] )*
+            => $qitem:ident: UNIT [ ] $( $queue:tt )*]
+    ) => {
+        quick_error!(ENUM_DEFINITION [ $($def)* ]
+            body [$($( #[$imeta] )* => $iitem ($(($( $ttyp ),+))*) {$({$( $svar: $styp ),*})*} )*
+                    $( #[$qmeta] )* => $qitem () {} ]
+            queue [ $($queue)* ]
+        );
+    };
+    // Tuple variant
+    (ENUM_DEFINITION [$( $def:tt )*]
+        body [$($( #[$imeta:meta] )*
+            => $iitem:ident ($(($( $ttyp:ty ),+))*) {$({$( $svar:ident: $styp:ty ),*})*} )* ]
+        queue [$( #[$qmeta:meta] )*
+            => $qitem:ident: TUPLE [$( $qvar:ident: $qtyp:ty ),+] $( $queue:tt )*]
+    ) => {
+        quick_error!(ENUM_DEFINITION [ $($def)* ]
+            body [$($( #[$imeta] )* => $iitem ($(($( $ttyp ),+))*) {$({$( $svar: $styp ),*})*} )*
+                    $( #[$qmeta] )* => $qitem (($( $qtyp ),*)) {} ]
+            queue [ $($queue)* ]
+        );
+    };
+    // Struct variant
+    (ENUM_DEFINITION [$( $def:tt )*]
+        body [$($( #[$imeta:meta] )*
+            => $iitem:ident ($(($( $ttyp:ty ),+))*) {$({$( $svar:ident: $styp:ty ),*})*} )* ]
+        queue [$( #[$qmeta:meta] )*
+            => $qitem:ident: STRUCT [$( $qvar:ident: $qtyp:ty ),*] $( $queue:tt )*]
+    ) => {
+        quick_error!(ENUM_DEFINITION [ $($def)* ]
+            body [$($( #[$imeta] )* => $iitem ($(($( $ttyp ),+))*) {$({$( $svar: $styp ),*})*} )*
+                    $( #[$qmeta] )* => $qitem () {{$( $qvar: $qtyp ),*}} ]
+            queue [ $($queue)* ]
+        );
+    };
+    (IMPLEMENTATIONS
+        $name:ident {$(
+            $item:ident: $imode:tt [$(#[$imeta:meta])*] [$( $var:ident: $typ:ty ),*] {$( $funcs:tt )*}
+        )*}
+    ) => {
+        #[allow(unused)]
+        #[allow(unknown_lints)]  // no unused_doc_comments in older rust
+        #[allow(renamed_and_removed_lints)]
+        #[allow(unused_doc_comment)]
+        #[allow(unused_doc_comments)]
+        impl ::std::fmt::Display for $name {
+            fn fmt(&self, fmt: &mut ::std::fmt::Formatter)
+                -> ::std::fmt::Result
+            {
+                match *self {
+                    $(
+                        $(#[$imeta])*
+                        quick_error!(ITEM_PATTERN
+                            $name $item: $imode [$( ref $var ),*]
+                        ) => {
+                            let display_fn = quick_error!(FIND_DISPLAY_IMPL
+                                $name $item: $imode
+                                {$( $funcs )*});
+
+                            display_fn(self, fmt)
+                        }
+                    )*
+                }
+            }
+        }
+        #[allow(unused)]
+        #[allow(unknown_lints)]  // no unused_doc_comments in older rust
+        #[allow(renamed_and_removed_lints)]
+        #[allow(unused_doc_comment)]
+        #[allow(unused_doc_comments)]
+        impl ::std::error::Error for $name {
+            fn cause(&self) -> Option<&::std::error::Error> {
+                match *self {
+                    $(
+                        $(#[$imeta])*
+                        quick_error!(ITEM_PATTERN
+                            $name $item: $imode [$( ref $var ),*]
+                        ) => {
+                            quick_error!(FIND_CAUSE_IMPL
+                                $item: $imode [$( $var ),*]
+                                {$( $funcs )*})
+                        }
+                    )*
+                }
+            }
+        }
+        $(
+            quick_error!(FIND_FROM_IMPL
+                $name $item: $imode [$( $var:$typ ),*]
+                {$( $funcs )*});
+        )*
+        $(
+            quick_error!(FIND_CONTEXT_IMPL
+                $name $item: $imode [$( $var:$typ ),*]
+                {$( $funcs )*});
+        )*
+    };
+    (FIND_DISPLAY_IMPL $name:ident $item:ident: $imode:tt
+        { display($self_:tt) -> ($( $exprs:tt )*) $( $tail:tt )*}
+    ) => {
+        |quick_error!(IDENT $self_): &$name, f: &mut ::std::fmt::Formatter| { write!(f, $( $exprs )*) }
+    };
+    (FIND_DISPLAY_IMPL $name:ident $item:ident: $imode:tt
+        { display($pattern:expr) $( $tail:tt )*}
+    ) => {
+        |_, f: &mut ::std::fmt::Formatter| { write!(f, $pattern) }
+    };
+    (FIND_DISPLAY_IMPL $name:ident $item:ident: $imode:tt
+        { display($pattern:expr, $( $exprs:tt )*) $( $tail:tt )*}
+    ) => {
+        |_, f: &mut ::std::fmt::Formatter| { write!(f, $pattern, $( $exprs )*) }
+    };
+    (FIND_DISPLAY_IMPL $name:ident $item:ident: $imode:tt
+        { $t:tt $( $tail:tt )*}
+    ) => {
+        quick_error!(FIND_DISPLAY_IMPL
+            $name $item: $imode
+            {$( $tail )*})
+    };
+    (FIND_DISPLAY_IMPL $name:ident $item:ident: $imode:tt
+        { }
+    ) => {
+        |self_: &$name, f: &mut ::std::fmt::Formatter| {
+            write!(f, "{:?}", self_)
+        }
+    };
+    (FIND_DESCRIPTION_IMPL $item:ident: $imode:tt $me:ident $fmt:ident
+        [$( $var:ident ),*]
+        { description($expr:expr) $( $tail:tt )*}
+    ) => {};
+    (FIND_DESCRIPTION_IMPL $item:ident: $imode:tt $me:ident $fmt:ident
+        [$( $var:ident ),*]
+        { $t:tt $( $tail:tt )*}
+    ) => {};
+    (FIND_DESCRIPTION_IMPL $item:ident: $imode:tt $me:ident $fmt:ident
+        [$( $var:ident ),*]
+        { }
+    ) => {};
+    (FIND_CAUSE_IMPL $item:ident: $imode:tt
+        [$( $var:ident ),*]
+        { cause($expr:expr) $( $tail:tt )*}
+    ) => {
+        Some($expr)
+    };
+    (FIND_CAUSE_IMPL $item:ident: $imode:tt
+        [$( $var:ident ),*]
+        { $t:tt $( $tail:tt )*}
+    ) => {
+        quick_error!(FIND_CAUSE_IMPL
+            $item: $imode [$( $var ),*]
+            { $($tail)* })
+    };
+    (FIND_CAUSE_IMPL $item:ident: $imode:tt
+        [$( $var:ident ),*]
+        { }
+    ) => {
+        None
+    };
+    // ----------------------------- FROM IMPL --------------------------
+    (FIND_FROM_IMPL $name:ident $item:ident: $imode:tt
+        [$( $var:ident: $typ:ty ),*]
+        { from() $( $tail:tt )*}
+    ) => {
+        $(
+            impl From<$typ> for $name {
+                fn from($var: $typ) -> $name {
+                    $name::$item($var)
+                }
+            }
+        )*
+        quick_error!(FIND_FROM_IMPL
+            $name $item: $imode [$( $var:$typ ),*]
+            {$( $tail )*});
+    };
+    (FIND_FROM_IMPL $name:ident $item:ident: UNIT
+        [ ]
+        { from($ftyp:ty) $( $tail:tt )*}
+    ) => {
+        impl From<$ftyp> for $name {
+            fn from(_discarded_error: $ftyp) -> $name {
+                $name::$item
+            }
+        }
+        quick_error!(FIND_FROM_IMPL
+            $name $item: UNIT [  ]
+            {$( $tail )*});
+    };
+    (FIND_FROM_IMPL $name:ident $item:ident: TUPLE
+        [$( $var:ident: $typ:ty ),*]
+        { from($fvar:ident: $ftyp:ty) -> ($( $texpr:expr ),*) $( $tail:tt )*}
+    ) => {
+        impl From<$ftyp> for $name {
+            fn from($fvar: $ftyp) -> $name {
+                $name::$item($( $texpr ),*)
+            }
+        }
+        quick_error!(FIND_FROM_IMPL
+            $name $item: TUPLE [$( $var:$typ ),*]
+            { $($tail)* });
+    };
+    (FIND_FROM_IMPL $name:ident $item:ident: STRUCT
+        [$( $var:ident: $typ:ty ),*]
+        { from($fvar:ident: $ftyp:ty) -> {$( $tvar:ident: $texpr:expr ),*} $( $tail:tt )*}
+    ) => {
+        impl From<$ftyp> for $name {
+            fn from($fvar: $ftyp) -> $name {
+                $name::$item {
+                    $( $tvar: $texpr ),*
+                }
+            }
+        }
+        quick_error!(FIND_FROM_IMPL
+            $name $item: STRUCT [$( $var:$typ ),*]
+            { $($tail)* });
+    };
+    (FIND_FROM_IMPL $name:ident $item:ident: $imode:tt
+        [$( $var:ident: $typ:ty ),*]
+        { $t:tt $( $tail:tt )*}
+    ) => {
+        quick_error!(FIND_FROM_IMPL
+            $name $item: $imode [$( $var:$typ ),*]
+            {$( $tail )*}
+        );
+    };
+    (FIND_FROM_IMPL $name:ident $item:ident: $imode:tt
+        [$( $var:ident: $typ:ty ),*]
+        { }
+    ) => {
+    };
+    // ----------------------------- CONTEXT IMPL --------------------------
+    (FIND_CONTEXT_IMPL $name:ident $item:ident: TUPLE
+        [$( $var:ident: $typ:ty ),*]
+        { context($cvar:ident: AsRef<$ctyp:ty>, $fvar:ident: $ftyp:ty)
+            -> ($( $texpr:expr ),*) $( $tail:tt )* }
+    ) => {
+        impl<T: AsRef<$ctyp>> From<$crate::Context<T, $ftyp>> for $name {
+            fn from(
+                $crate::Context($cvar, $fvar): $crate::Context<T, $ftyp>)
+                -> $name
+            {
+                $name::$item($( $texpr ),*)
+            }
+        }
+        quick_error!(FIND_CONTEXT_IMPL
+            $name $item: TUPLE [$( $var:$typ ),*]
+            { $($tail)* });
+    };
+    (FIND_CONTEXT_IMPL $name:ident $item:ident: TUPLE
+        [$( $var:ident: $typ:ty ),*]
+        { context($cvar:ident: $ctyp:ty, $fvar:ident: $ftyp:ty)
+            -> ($( $texpr:expr ),*) $( $tail:tt )* }
+    ) => {
+        impl<'a> From<$crate::Context<$ctyp, $ftyp>> for $name {
+            fn from(
+                $crate::Context($cvar, $fvar): $crate::Context<$ctyp, $ftyp>)
+                -> $name
+            {
+                $name::$item($( $texpr ),*)
+            }
+        }
+        quick_error!(FIND_CONTEXT_IMPL
+            $name $item: TUPLE [$( $var:$typ ),*]
+            { $($tail)* });
+    };
+    (FIND_CONTEXT_IMPL $name:ident $item:ident: STRUCT
+        [$( $var:ident: $typ:ty ),*]
+        { context($cvar:ident: AsRef<$ctyp:ty>, $fvar:ident: $ftyp:ty)
+            -> {$( $tvar:ident: $texpr:expr ),*} $( $tail:tt )* }
+    ) => {
+        impl<T: AsRef<$ctyp>> From<$crate::Context<T, $ftyp>> for $name {
+            fn from(
+                $crate::Context($cvar, $fvar): $crate::Context<$ctyp, $ftyp>)
+                -> $name
+            {
+                $name::$item {
+                    $( $tvar: $texpr ),*
+                }
+            }
+        }
+        quick_error!(FIND_CONTEXT_IMPL
+            $name $item: STRUCT [$( $var:$typ ),*]
+            { $($tail)* });
+    };
+    (FIND_CONTEXT_IMPL $name:ident $item:ident: STRUCT
+        [$( $var:ident: $typ:ty ),*]
+        { context($cvar:ident: $ctyp:ty, $fvar:ident: $ftyp:ty)
+            -> {$( $tvar:ident: $texpr:expr ),*} $( $tail:tt )* }
+    ) => {
+        impl<'a> From<$crate::Context<$ctyp, $ftyp>> for $name {
+            fn from(
+                $crate::Context($cvar, $fvar): $crate::Context<$ctyp, $ftyp>)
+                -> $name
+            {
+                $name::$item {
+                    $( $tvar: $texpr ),*
+                }
+            }
+        }
+        quick_error!(FIND_CONTEXT_IMPL
+            $name $item: STRUCT [$( $var:$typ ),*]
+            { $($tail)* });
+    };
+    (FIND_CONTEXT_IMPL $name:ident $item:ident: $imode:tt
+        [$( $var:ident: $typ:ty ),*]
+        { $t:tt $( $tail:tt )*}
+    ) => {
+        quick_error!(FIND_CONTEXT_IMPL
+            $name $item: $imode [$( $var:$typ ),*]
+            {$( $tail )*}
+        );
+    };
+    (FIND_CONTEXT_IMPL $name:ident $item:ident: $imode:tt
+        [$( $var:ident: $typ:ty ),*]
+        { }
+    ) => {
+    };
+    // ----------------------------- ITEM IMPL --------------------------
+    (ITEM_BODY $(#[$imeta:meta])* $item:ident: UNIT
+    ) => { };
+    (ITEM_BODY $(#[$imeta:meta])* $item:ident: TUPLE
+        [$( $typ:ty ),*]
+    ) => {
+        ($( $typ ),*)
+    };
+    (ITEM_BODY $(#[$imeta:meta])* $item:ident: STRUCT
+        [$( $var:ident: $typ:ty ),*]
+    ) => {
+        {$( $var:$typ ),*}
+    };
+    (ITEM_PATTERN $name:ident $item:ident: UNIT []
+    ) => {
+        $name::$item
+    };
+    (ITEM_PATTERN $name:ident $item:ident: TUPLE
+        [$( ref $var:ident ),*]
+    ) => {
+        $name::$item ($( ref $var ),*)
+    };
+    (ITEM_PATTERN $name:ident $item:ident: STRUCT
+        [$( ref $var:ident ),*]
+    ) => {
+        $name::$item {$( ref $var ),*}
+    };
+    // This one should match all allowed sequences in "funcs" but not match
+    // anything else.
+    // This is to contrast FIND_* clauses which just find stuff they need and
+    // skip everything else completely
+    (ERROR_CHECK $imode:tt display($self_:tt) -> ($( $exprs:tt )*) $( $tail:tt )*)
+    => { quick_error!(ERROR_CHECK $imode $($tail)*); };
+    (ERROR_CHECK $imode:tt display($pattern: expr) $( $tail:tt )*)
+    => { quick_error!(ERROR_CHECK $imode $($tail)*); };
+    (ERROR_CHECK $imode:tt display($pattern: expr, $( $exprs:tt )*) $( $tail:tt )*)
+    => { quick_error!(ERROR_CHECK $imode $($tail)*); };
+    (ERROR_CHECK $imode:tt description($expr:expr) $( $tail:tt )*)
+    => { quick_error!(ERROR_CHECK $imode $($tail)*); };
+    (ERROR_CHECK $imode:tt cause($expr:expr) $($tail:tt)*)
+    => { quick_error!(ERROR_CHECK $imode $($tail)*); };
+    (ERROR_CHECK $imode:tt from() $($tail:tt)*)
+    => { quick_error!(ERROR_CHECK $imode $($tail)*); };
+    (ERROR_CHECK $imode:tt from($ftyp:ty) $($tail:tt)*)
+    => { quick_error!(ERROR_CHECK $imode $($tail)*); };
+    (ERROR_CHECK TUPLE from($fvar:ident: $ftyp:ty) -> ($( $e:expr ),*) $( $tail:tt )*)
+    => { quick_error!(ERROR_CHECK TUPLE $($tail)*); };
+    (ERROR_CHECK STRUCT from($fvar:ident: $ftyp:ty) -> {$( $v:ident: $e:expr ),*} $( $tail:tt )*)
+    => { quick_error!(ERROR_CHECK STRUCT $($tail)*); };
+
+    (ERROR_CHECK TUPLE context($cvar:ident: $ctyp:ty, $fvar:ident: $ftyp:ty)
+        -> ($( $e:expr ),*) $( $tail:tt )*)
+    => { quick_error!(ERROR_CHECK TUPLE $($tail)*); };
+    (ERROR_CHECK STRUCT context($cvar:ident: $ctyp:ty, $fvar:ident: $ftyp:ty)
+        -> {$( $v:ident: $e:expr ),*} $( $tail:tt )*)
+    => { quick_error!(ERROR_CHECK STRUCT $($tail)*); };
+
+    (ERROR_CHECK $imode:tt ) => {};
+    // Utility functions
+    (IDENT $ident:ident) => { $ident }
+}
+
+
+/// Generic context type
+///
+/// Used mostly as a transport for `ResultExt::context` method
+#[derive(Debug)]
+pub struct Context<X, E>(pub X, pub E);
+
+/// Result extension trait adding a `context` method
+pub trait ResultExt<T, E> {
+    /// The method is use to add context information to current operation
+    ///
+    /// The context data is then used in error constructor to store additional
+    /// information within error. For example, you may add a filename as a
+    /// context for file operation. See crate documentation for the actual
+    /// example.
+    fn context<X>(self, x: X) -> Result<T, Context<X, E>>;
+}
+
+impl<T, E> ResultExt<T, E> for Result<T, E> {
+    fn context<X>(self, x: X) -> Result<T, Context<X, E>> {
+        self.map_err(|e| Context(x, e))
+    }
+}
+
+
+
+#[cfg(test)]
+#[allow(deprecated)]
+mod test {
+    use std::num::{ParseFloatError, ParseIntError};
+    use std::str::Utf8Error;
+    use std::string::FromUtf8Error;
+    use std::error::Error;
+    use std::path::{Path, PathBuf};
+
+    use super::ResultExt;
+
+    quick_error! {
+        #[derive(Debug)]
+        pub enum Bare {
+            One
+            Two
+        }
+    }
+
+    #[test]
+    fn bare_item_direct() {
+        assert_eq!(format!("{}", Bare::One), "One".to_string());
+        assert_eq!(format!("{:?}", Bare::One), "One".to_string());
+        assert!(Bare::One.cause().is_none());
+    }
+    #[test]
+    fn bare_item_trait() {
+        let err: &Error = &Bare::Two;
+        assert_eq!(format!("{}", err), "Two".to_string());
+        assert_eq!(format!("{:?}", err), "Two".to_string());
+        assert!(err.cause().is_none());
+    }
+
+    quick_error! {
+        #[derive(Debug)]
+        pub enum Wrapper wraps Wrapped {
+            One
+            Two(s: String) {
+                display("two: {}", s)
+                from()
+            }
+        }
+    }
+
+    #[test]
+    fn wrapper() {
+        assert_eq!(format!("{}", Wrapper::from(Wrapped::One)),
+            "One".to_string());
+        assert_eq!(format!("{}",
+            Wrapper::from(Wrapped::from(String::from("hello")))),
+            "two: hello".to_string());
+        assert_eq!(format!("{:?}", Wrapper::from(Wrapped::One)),
+            "Wrapper(One)".to_string());
+    }
+
+    quick_error! {
+        #[derive(Debug, PartialEq)]
+        pub enum TupleWrapper {
+            /// ParseFloat Error
+            ParseFloatError(err: ParseFloatError) {
+                from()
+                display("parse float error: {err}", err=err)
+                cause(err)
+            }
+            Other(descr: &'static str) {
+                display("Error: {}", descr)
+            }
+            /// FromUtf8 Error
+            FromUtf8Error(err: Utf8Error, source: Vec<u8>) {
+                cause(err)
+                display(me) -> ("{desc} at index {pos}: {err}", desc="utf8 error", pos=err.valid_up_to(), err=err)
+                from(err: FromUtf8Error) -> (err.utf8_error().clone(), err.into_bytes())
+            }
+            Discard {
+                from(&'static str)
+            }
+            Singleton {
+                display("Just a string")
+            }
+        }
+    }
+
+    #[test]
+    fn tuple_wrapper_err() {
+        let cause = "one and a half times pi".parse::<f32>().unwrap_err();
+        let err = TupleWrapper::ParseFloatError(cause.clone());
+        assert_eq!(format!("{}", err), format!("parse float error: {}", cause));
+        assert_eq!(format!("{:?}", err), format!("ParseFloatError({:?})", cause));
+        assert_eq!(format!("{:?}", err.cause().unwrap()), format!("{:?}", cause));
+    }
+
+    #[test]
+    fn tuple_wrapper_trait_str() {
+        let desc = "hello";
+        let err: &Error = &TupleWrapper::Other(desc);
+        assert_eq!(format!("{}", err), format!("Error: {}", desc));
+        assert_eq!(format!("{:?}", err), format!("Other({:?})", desc));
+        assert!(err.cause().is_none());
+    }
+
+    #[test]
+    fn tuple_wrapper_trait_two_fields() {
+        let invalid_utf8: Vec<u8> = vec![0, 159, 146, 150];
+        let cause = String::from_utf8(invalid_utf8.clone()).unwrap_err().utf8_error();
+        let err: &Error = &TupleWrapper::FromUtf8Error(cause.clone(), invalid_utf8.clone());
+        assert_eq!(format!("{}", err), format!("{desc} at index {pos}: {cause}", desc="utf8 error", pos=cause.valid_up_to(), cause=cause));
+        assert_eq!(format!("{:?}", err), format!("FromUtf8Error({:?}, {:?})", cause, invalid_utf8));
+        assert_eq!(format!("{:?}", err.cause().unwrap()), format!("{:?}", cause));
+    }
+
+    #[test]
+    fn tuple_wrapper_from() {
+        let cause = "one and a half times pi".parse::<f32>().unwrap_err();
+        let err = TupleWrapper::ParseFloatError(cause.clone());
+        let err_from: TupleWrapper = From::from(cause);
+        assert_eq!(err_from, err);
+    }
+
+    #[test]
+    fn tuple_wrapper_custom_from() {
+        let invalid_utf8: Vec<u8> = vec![0, 159, 146, 150];
+        let cause = String::from_utf8(invalid_utf8.clone()).unwrap_err();
+        let err = TupleWrapper::FromUtf8Error(cause.utf8_error().clone(), invalid_utf8);
+        let err_from: TupleWrapper = From::from(cause);
+        assert_eq!(err_from, err);
+    }
+
+    #[test]
+    fn tuple_wrapper_discard() {
+        let err: TupleWrapper = From::from("hello");
+        assert_eq!(format!("{}", err), format!("Discard"));
+        assert_eq!(format!("{:?}", err), format!("Discard"));
+        assert!(err.cause().is_none());
+    }
+
+    #[test]
+    fn tuple_wrapper_singleton() {
+        let err: TupleWrapper = TupleWrapper::Singleton;
+        assert_eq!(format!("{}", err), format!("Just a string"));
+        assert_eq!(format!("{:?}", err), format!("Singleton"));
+        assert!(err.cause().is_none());
+    }
+
+    quick_error! {
+        #[derive(Debug, PartialEq)]
+        pub enum StructWrapper {
+            // Utf8 Error
+            Utf8Error{ err: Utf8Error, hint: Option<&'static str> } {
+                cause(err)
+                display(me) -> ("{desc} at index {pos}: {err}", desc="utf8 error", pos=err.valid_up_to(), err=err)
+                from(err: Utf8Error) -> { err: err, hint: None }
+            }
+            // Utf8 Error
+            ExcessComma { descr: &'static str, } {
+                display("Error: {}", descr)
+            }
+        }
+    }
+
+    #[test]
+    fn struct_wrapper_err() {
+        let invalid_utf8: Vec<u8> = vec![0, 159, 146, 150];
+        let cause = String::from_utf8(invalid_utf8.clone()).unwrap_err().utf8_error();
+        let err: &Error = &StructWrapper::Utf8Error{ err: cause.clone(), hint: Some("nonsense") };
+        assert_eq!(format!("{}", err), format!("{desc} at index {pos}: {cause}", desc="utf8 error", pos=cause.valid_up_to(), cause=cause));
+        assert_eq!(format!("{:?}", err), format!("Utf8Error {{ err: {:?}, hint: {:?} }}", cause, Some("nonsense")));
+        assert_eq!(format!("{:?}", err.cause().unwrap()), format!("{:?}", cause));
+    }
+
+    #[test]
+    fn struct_wrapper_struct_from() {
+        let invalid_utf8: Vec<u8> = vec![0, 159, 146, 150];
+        let cause = String::from_utf8(invalid_utf8.clone()).unwrap_err().utf8_error();
+        let err = StructWrapper::Utf8Error{ err: cause.clone(), hint: None };
+        let err_from: StructWrapper = From::from(cause);
+        assert_eq!(err_from, err);
+    }
+
+    #[test]
+    fn struct_wrapper_excess_comma() {
+        let descr = "hello";
+        let err = StructWrapper::ExcessComma { descr: descr };
+        assert_eq!(format!("{}", err), format!("Error: {}", descr));
+        assert_eq!(format!("{:?}", err), format!("ExcessComma {{ descr: {:?} }}", descr));
+        assert!(err.cause().is_none());
+    }
+
+    quick_error! {
+        #[derive(Debug)]
+        pub enum ContextErr {
+            Float(src: String, err: ParseFloatError) {
+                context(s: &'a str, e: ParseFloatError) -> (s.to_string(), e)
+                display("Float error {:?}: {}", src, err)
+            }
+            Int { src: String, err: ParseIntError } {
+                context(s: &'a str, e: ParseIntError)
+                    -> {src: s.to_string(), err: e}
+                display("Int error {:?}: {}", src, err)
+            }
+            Utf8(path: PathBuf, err: Utf8Error) {
+                context(p: AsRef<Path>, e: Utf8Error)
+                    -> (p.as_ref().to_path_buf(), e)
+                display("Path error at {:?}: {}", path, err)
+            }
+            Utf8Str(s: String, err: ::std::io::Error) {
+                context(s: AsRef<str>, e: ::std::io::Error)
+                    -> (s.as_ref().to_string(), e)
+                display("Str error {:?}: {}", s, err)
+            }
+        }
+    }
+
+    #[test]
+    fn parse_float_error() {
+        fn parse_float(s: &str) -> Result<f32, ContextErr> {
+            Ok(try!(s.parse().context(s)))
+        }
+        assert_eq!(format!("{}", parse_float("12ab").unwrap_err()),
+            r#"Float error "12ab": invalid float literal"#);
+    }
+
+    #[test]
+    fn parse_int_error() {
+        fn parse_int(s: &str) -> Result<i32, ContextErr> {
+            Ok(try!(s.parse().context(s)))
+        }
+        assert_eq!(format!("{}", parse_int("12.5").unwrap_err()),
+            r#"Int error "12.5": invalid digit found in string"#);
+    }
+
+    #[test]
+    fn debug_context() {
+        fn parse_int(s: &str) -> i32 {
+            s.parse().context(s).unwrap()
+        }
+        assert_eq!(parse_int("12"), 12);
+        assert_eq!(format!("{:?}", "x".parse::<i32>().context("x")),
+            r#"Err(Context("x", ParseIntError { kind: InvalidDigit }))"#);
+    }
+
+    #[test]
+    fn path_context() {
+        fn parse_utf<P: AsRef<Path>>(s: &[u8], p: P)
+            -> Result<(), ContextErr>
+        {
+            try!(::std::str::from_utf8(s).context(p));
+            Ok(())
+        }
+        let etext = parse_utf(b"a\x80\x80", "/etc").unwrap_err().to_string();
+        assert!(etext.starts_with(
+            "Path error at \"/etc\": invalid utf-8"));
+        let etext = parse_utf(b"\x80\x80", PathBuf::from("/tmp")).unwrap_err()
+            .to_string();
+        assert!(etext.starts_with(
+            "Path error at \"/tmp\": invalid utf-8"));
+    }
+
+    #[test]
+    fn conditional_compilation() {
+        quick_error! {
+            #[allow(dead_code)]
+            #[derive(Debug)]
+            pub enum Test {
+                #[cfg(feature = "foo")]
+                Variant
+            }
+        }
+    }
+}