example.diff

--- examples/context.rs	2016-06-17 00:55:28.578244188 +0300
+++ examples/backtrace.rs	2016-06-17 00:59:10.613723109 +0300
@@ -1,4 +1,5 @@
 #[macro_use(quick_error)] extern crate quick_error;
+extern crate backtrace;
 
 use std::io::{self, stderr, Read, Write};
 use std::fs::File;
@@ -7,6 +8,7 @@
 use std::path::{Path, PathBuf};
 
 use quick_error::ResultExt;
+use backtrace::Backtrace;
 
 quick_error! {
     #[derive(Debug)]
@@ -14,10 +16,10 @@
         NoFileName {
             description("no file name specified")
         }
-        Io(err: io::Error, path: PathBuf) {
-            display("could not read file {:?}: {}", path, err)
+        Io(err: io::Error, path: PathBuf, tb: Backtrace) {
+            display("could not read file {:?}: {}\n{:?}", path, err, tb)
             context(path: &'a Path, err: io::Error)
-                -> (err, path.to_path_buf())
+                -> (err, path.to_path_buf(), Backtrace::new())
         }
         Parse(err: ParseIntError, path: PathBuf) {
             display("could not parse file {:?}: {}", path, err)