ignore: fix custom ignore name bug

This commit fixes a bug in the handling of custom gitignore file names.
Previously, the directory walker would check for whether there were any
ignore rules present, but this check didn't incorporate the custom gitignore
rules. At a high level, this permits custom gitignore names to be used
even if no other source of gitignore rules is used.

Fixes BurntSushi#800

ignore/src/dir.rs

@@ -73,13 +73,6 @@ struct IgnoreOptions {
     git_exclude: bool,
 }
 
-impl IgnoreOptions {
-    /// Returns true if at least one type of ignore rules should be matched.
-    fn has_any_ignore_options(&self) -> bool {
-        self.ignore || self.git_global || self.git_ignore || self.git_exclude
-    }
-}
-
 /// Ignore is a matcher useful for recursively walking one or more directories.
 #[derive(Clone, Debug)]
 pub struct Ignore(Arc<IgnoreInner>);
@@ -267,6 +260,15 @@ impl Ignore {
         (ig, errs.into_error_option())
     }
 
+    /// Returns true if at least one type of ignore rule should be matched.
+    fn has_any_ignore_rules(&self) -> bool {
+        let opts = self.0.opts;
+        let has_custom_ignore_files = !self.0.custom_ignore_filenames.is_empty();
+
+        opts.ignore || opts.git_global || opts.git_ignore
+                    || opts.git_exclude || has_custom_ignore_files
+    }
+
     /// Returns a match indicating whether the given file path should be
     /// ignored or not.
     ///
@@ -295,7 +297,7 @@ impl Ignore {
             }
         }
         let mut whitelisted = Match::None;
-        if self.0.opts.has_any_ignore_options() {
+        if self.has_any_ignore_rules() {
             let mat = self.matched_ignore(path, is_dir);
             if mat.is_ignore() {
                 return mat;

ignore/src/walk.rs

@@ -1585,6 +1585,26 @@ mod tests {
         assert_paths(td.path(), &builder, &["bar", "a", "a/bar"]);
     }
 
+    #[test]
+    fn custom_ignore_exclusive_use() {
+        let td = TempDir::new("walk-test-").unwrap();
+        let custom_ignore = ".customignore";
+        mkdirp(td.path().join("a"));
+        wfile(td.path().join(custom_ignore), "foo");
+        wfile(td.path().join("foo"), "");
+        wfile(td.path().join("a/foo"), "");
+        wfile(td.path().join("bar"), "");
+        wfile(td.path().join("a/bar"), "");
+
+        let mut builder = WalkBuilder::new(td.path());
+        builder.ignore(false);
+        builder.git_ignore(false);
+        builder.git_global(false);
+        builder.git_exclude(false);
+        builder.add_custom_ignore_filename(&custom_ignore);
+        assert_paths(td.path(), &builder, &["bar", "a", "a/bar"]);
+    }
+
     #[test]
     fn gitignore() {
         let td = TempDir::new("walk-test-").unwrap();