ignore: upgrade to walkdir 2

The uninteresting bits of this commit involve mechanical changes for
updates to walkdir 2. The more interesting bits of this commit are the
breaking changes, although none of them should require any significant
change on users of this library. The breaking changes are as follows:

* `DirEntry::path_is_symbolic_link` has been renamed to
  `DirEntry::path_is_symlink`. This matches the conventions in the
  standard library, and also the corresponding name change in walkdir.
* Removed the `From<walkdir::Error> for ignore::Error` impl. This was
  intended to only be used internally, but was the only thing that
  made `walkdir` a public dependency of `ignore`. Therefore, we remove
  it since it seems unnecessary.
* Renamed `WalkBuilder::sort_by` to `WalkBuilder::sort_by_file_name`,
  and changed the type of the comparator from

    Fn(&OsString, &OsString) -> cmp::Ordering + 'static

  to

    Fn(&OsStr, &OsStr) -> cmp::Ordering + Send + Sync + 'static

  The corresponding change in `walkdir` retains the `sort_by` name, but
  gives the comparator a pair of `&DirEntry` values instead of a pair
  of `&OsStr` values. Ideally, `ignore` would hand off its own pair of
  `&ignore::DirEntry` values, but this requires more design work. So for
  now, we retain previous functionality, but leave room to make a proper
  `sort_by` method.

[breaking-change]

3 files changed, 51 insertions, 43 deletions

diff --git a/ignore/Cargo.toml b/ignore/Cargo.toml
index 0fa01090..660ee39c 100644
--- a/ignore/Cargo.toml
+++ b/ignore/Cargo.toml
@@ -24,8 +24,9 @@ lazy_static = "0.2"
 log = "0.3"
 memchr = "2"
 regex = "0.2.1"
+same-file = "1"
 thread_local = "0.3.2"
-walkdir = "1.0.7"
+walkdir = "2"
 
 [dev-dependencies]
 tempdir = "0.3.5"
diff --git a/ignore/src/lib.rs b/ignore/src/lib.rs
index d053014c..456079c1 100644
--- a/ignore/src/lib.rs
+++ b/ignore/src/lib.rs
@@ -54,6 +54,7 @@ extern crate lazy_static;
 extern crate log;
 extern crate memchr;
 extern crate regex;
+extern crate same_file;
 #[cfg(test)]
 extern crate tempdir;
 extern crate thread_local;
@@ -198,6 +199,29 @@ impl Error {
         }
         errline.with_path(path)
     }
+
+    /// Build an error from a walkdir error.
+    fn from_walkdir(err: walkdir::Error) -> Error {
+        let depth = err.depth();
+        if let (Some(anc), Some(child)) = (err.loop_ancestor(), err.path()) {
+            return Error::WithDepth {
+                depth: depth,
+                err: Box::new(Error::Loop {
+                    ancestor: anc.to_path_buf(),
+                    child: child.to_path_buf(),
+                }),
+            };
+        }
+        let path = err.path().map(|p| p.to_path_buf());
+        let mut ig_err = Error::Io(io::Error::from(err));
+        if let Some(path) = path {
+            ig_err = Error::WithPath {
+                path: path,
+                err: Box::new(ig_err),
+            };
+        }
+        ig_err
+    }
 }
 
 impl error::Error for Error {
@@ -258,30 +282,6 @@ impl From<io::Error> for Error {
     }
 }
 
-impl From<walkdir::Error> for Error {
-    fn from(err: walkdir::Error) -> Error {
-        let depth = err.depth();
-        if let (Some(anc), Some(child)) = (err.loop_ancestor(), err.path()) {
-            return Error::WithDepth {
-                depth: depth,
-                err: Box::new(Error::Loop {
-                    ancestor: anc.to_path_buf(),
-                    child: child.to_path_buf(),
-                }),
-            };
-        }
-        let path = err.path().map(|p| p.to_path_buf());
-        let mut ig_err = Error::Io(io::Error::from(err));
-        if let Some(path) = path {
-            ig_err = Error::WithPath {
-                path: path,
-                err: Box::new(ig_err),
-            };
-        }
-        ig_err
-    }
-}
-
 #[derive(Debug, Default)]
 struct PartialErrorBuilder(Vec<Error>);
 
diff --git a/ignore/src/walk.rs b/ignore/src/walk.rs
index 3df7933a..8a15984d 100644
--- a/ignore/src/walk.rs
+++ b/ignore/src/walk.rs
@@ -1,5 +1,5 @@
 use std::cmp;
-use std::ffi::{OsStr, OsString};
+use std::ffi::OsStr;
 use std::fmt;
 use std::fs::{self, FileType, Metadata};
 use std::io;
@@ -11,7 +11,8 @@ use std::time::Duration;
 use std::vec;
 
 use crossbeam::sync::MsQueue;
-use walkdir::{self, WalkDir, WalkDirIterator, is_same_file};
+use same_file::is_same_file;
+use walkdir::{self, WalkDir};
 
 use dir::{Ignore, IgnoreBuilder};
 use gitignore::GitignoreBuilder;
@@ -36,8 +37,8 @@ impl DirEntry {
     }
 
     /// Whether this entry corresponds to a symbolic link or not.
-    pub fn path_is_symbolic_link(&self) -> bool {
-        self.dent.path_is_symbolic_link()
+    pub fn path_is_symlink(&self) -> bool {
+        self.dent.path_is_symlink()
     }
 
     /// Returns true if and only if this entry corresponds to stdin.
@@ -137,12 +138,12 @@ impl DirEntryInner {
         }
     }
 
-    fn path_is_symbolic_link(&self) -> bool {
+    fn path_is_symlink(&self) -> bool {
         use self::DirEntryInner::*;
         match *self {
             Stdin => false,
-            Walkdir(ref x) => x.path_is_symbolic_link(),
-            Raw(ref x) => x.path_is_symbolic_link(),
+            Walkdir(ref x) => x.path_is_symlink(),
+            Raw(ref x) => x.path_is_symlink(),
         }
     }
 
@@ -199,6 +200,7 @@ impl DirEntryInner {
 
     #[cfg(unix)]
     fn ino(&self) -> Option<u64> {
+        use walkdir::DirEntryExt;
         use self::DirEntryInner::*;
         match *self {
             Stdin => None,
@@ -244,7 +246,7 @@ impl DirEntryRaw {
         &self.path
     }
 
-    fn path_is_symbolic_link(&self) -> bool {
+    fn path_is_symlink(&self) -> bool {
         self.ty.is_symlink() || self.follow_link
     }
 
@@ -404,7 +406,9 @@ pub struct WalkBuilder {
     max_depth: Option<usize>,
     max_filesize: Option<u64>,
     follow_links: bool,
-    sorter: Option<Arc<Fn(&OsString, &OsString) -> cmp::Ordering + 'static>>,
+    sorter: Option<Arc<
+        Fn(&OsStr, &OsStr) -> cmp::Ordering + Send + Sync + 'static
+    >>,
     threads: usize,
 }
 
@@ -458,7 +462,9 @@ impl WalkBuilder {
                 }
                 if let Some(ref cmp) = cmp {
                     let cmp = cmp.clone();
-                    wd = wd.sort_by(move |a, b| cmp(a, b));
+                    wd = wd.sort_by(move |a, b| {
+                        cmp(a.file_name(), b.file_name())
+                    });
                 }
                 (p.to_path_buf(), Some(WalkEventIter::from(wd)))
             }
@@ -572,16 +578,16 @@ impl WalkBuilder {
     }
 
     /// Enables all the standard ignore filters.
-    /// 
+    ///
     /// This toggles, as a group, all the filters that are enabled by default:
-    /// 
+    ///
     /// - [hidden()](#method.hidden)
     /// - [parents()](#method.parents)
     /// - [ignore()](#method.ignore)
     /// - [git_ignore()](#method.git_ignore)
     /// - [git_global()](#method.git_global)
     /// - [git_exclude()](#method.git_exclude)
-    /// 
+    ///
     /// They may still be toggled individually after calling this function.
     ///
     /// This is (by definition) enabled by default.
@@ -662,7 +668,7 @@ impl WalkBuilder {
         self
     }
 
-    /// Set a function for sorting directory entries.
+    /// Set a function for sorting directory entries by file name.
     ///
     /// If a compare function is set, the resulting iterator will return all
     /// paths in sorted order. The compare function will be called to compare
@@ -670,8 +676,9 @@ impl WalkBuilder {
     /// entry.
     ///
     /// Note that this is not used in the parallel iterator.
-    pub fn sort_by<F>(&mut self, cmp: F) -> &mut WalkBuilder
-            where F: Fn(&OsString, &OsString) -> cmp::Ordering + 'static {
+    pub fn sort_by_file_name<F>(&mut self, cmp: F) -> &mut WalkBuilder
+    where F: Fn(&OsStr, &OsStr) -> cmp::Ordering + Send + Sync + 'static
+    {
         self.sorter = Some(Arc::new(cmp));
         self
     }
@@ -752,7 +759,7 @@ impl Iterator for Walk {
             };
             match ev {
                 Err(err) => {
-                    return Some(Err(Error::from(err)));
+                    return Some(Err(Error::from_walkdir(err)));
                 }
                 Ok(WalkEvent::Exit) => {
                     self.ig = self.ig.parent().unwrap();
@@ -788,7 +795,7 @@ impl Iterator for Walk {
 /// the entire contents of a directory have been enumerated.
 struct WalkEventIter {
     depth: usize,
-    it: walkdir::Iter,
+    it: walkdir::IntoIter,
     next: Option<Result<walkdir::DirEntry, walkdir::Error>>,
 }