deps: drop tempfile

We were only using it to create temporary directories for `ignore`
tests, but it pulls in a bunch of dependencies and we don't really need
randomness. So just use our own simple wrapper instead.

ignore/Cargo.toml

@@ -31,8 +31,5 @@ walkdir = "2.2.7"
 [target.'cfg(windows)'.dependencies.winapi-util]
 version = "0.1.2"
 
-[dev-dependencies]
-tempfile = "3.0.5"
-
 [features]
 simd-accel = ["globset/simd-accel"]

ignore/src/dir.rs

@@ -721,10 +721,9 @@ mod tests {
     use std::io::Write;
     use std::path::Path;
 
-    use tempfile::{self, TempDir};
-
     use dir::IgnoreBuilder;
     use gitignore::Gitignore;
+    use tests::TempDir;
     use Error;
 
     fn wfile<P: AsRef<Path>>(path: P, contents: &str) {
@@ -744,7 +743,7 @@ mod tests {
     }
 
     fn tmpdir(prefix: &str) -> TempDir {
-        tempfile::Builder::new().prefix(prefix).tempdir().unwrap()
+        TempDir::new().unwrap()
     }
 
     #[test]

ignore/src/lib.rs

@@ -55,8 +55,6 @@ extern crate log;
 extern crate memchr;
 extern crate regex;
 extern crate same_file;
-#[cfg(test)]
-extern crate tempfile;
 extern crate thread_local;
 extern crate walkdir;
 #[cfg(windows)]
@@ -442,3 +440,66 @@ impl<T> Match<T> {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::env;
+    use std::error;
+    use std::fs;
+    use std::path::{Path, PathBuf};
+    use std::result;
+
+    /// A convenient result type alias.
+    pub type Result<T> =
+        result::Result<T, Box<dyn error::Error + Send + Sync>>;
+
+    macro_rules! err {
+        ($($tt:tt)*) => {
+            Box::<dyn error::Error + Send + Sync>::from(format!($($tt)*))
+        }
+    }
+
+    /// A simple wrapper for creating a temporary directory that is
+    /// automatically deleted when it's dropped.
+    ///
+    /// We use this in lieu of tempfile because tempfile brings in too many
+    /// dependencies.
+    #[derive(Debug)]
+    pub struct TempDir(PathBuf);
+
+    impl Drop for TempDir {
+        fn drop(&mut self) {
+            fs::remove_dir_all(&self.0).unwrap();
+        }
+    }
+
+    impl TempDir {
+        /// Create a new empty temporary directory under the system's configured
+        /// temporary directory.
+        pub fn new() -> Result<TempDir> {
+            use std::sync::atomic::{AtomicUsize, Ordering};
+
+            static TRIES: usize = 100;
+            static COUNTER: AtomicUsize = AtomicUsize::new(0);
+
+            let tmpdir = env::temp_dir();
+            for _ in 0..TRIES {
+                let count = COUNTER.fetch_add(1, Ordering::SeqCst);
+                let path = tmpdir.join("rust-ignore").join(count.to_string());
+                if path.is_dir() {
+                    continue;
+                }
+                fs::create_dir_all(&path).map_err(|e| {
+                    err!("failed to create {}: {}", path.display(), e)
+                })?;
+                return Ok(TempDir(path));
+            }
+            Err(err!("failed to create temp dir after {} tries", TRIES))
+        }
+
+        /// Return the underlying path to this temporary directory.
+        pub fn path(&self) -> &Path {
+            &self.0
+        }
+    }
+}

ignore/src/walk.rs

@@ -1730,8 +1730,7 @@ mod tests {
     use std::path::Path;
     use std::sync::{Arc, Mutex};
 
-    use tempfile::{self, TempDir};
-
+    use tests::TempDir;
     use super::{DirEntry, WalkBuilder, WalkState};
 
     fn wfile<P: AsRef<Path>>(path: P, contents: &str) {
@@ -1818,7 +1817,7 @@ mod tests {
     }
 
     fn tmpdir(prefix: &str) -> TempDir {
-        tempfile::Builder::new().prefix(prefix).tempdir().unwrap()
+        TempDir::new().unwrap()
     }
 
     fn assert_paths(