binding: Restore handling of multiple symbols w/ same name

Even though normal aliases don't cause this, simple (single-use) aliases still do cause it.

highlight/src/lib.rs

@@ -3,7 +3,7 @@ mod escape;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 use serde_derive::*;
 use std::cmp;
-use std::fmt::Write;
+use std::fmt::{self, Write};
 use std::mem::transmute;
 use std::str;
 use std::usize;
@@ -572,8 +572,9 @@ where
     }
 }
 
-impl<'a, T: Fn(&str) -> Option<(Language, &'a PropertySheet<Properties>)>> Iterator
-    for Highlighter<'a, T>
+impl<'a, T> Iterator for Highlighter<'a, T>
+where
+    T: Fn(&str) -> Option<(Language, &'a PropertySheet<Properties>)>,
 {
     type Item = HighlightEvent<'a>;
 
@@ -653,6 +654,31 @@ impl<'a, T: Fn(&str) -> Option<(Language, &'a PropertySheet<Properties>)>> Itera
     }
 }
 
+impl<'a, T> fmt::Debug for Highlighter<'a, T>
+where
+    T: Fn(&str) -> Option<(Language, &'a PropertySheet<Properties>)>,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if let Some(layer) = self.layers.first() {
+            let node = layer.cursor.node();
+            let position = if layer.at_node_end {
+                node.end_position()
+            } else {
+                node.start_position()
+            };
+            write!(
+                f,
+                "{{Highlighter position: {:?}, kind: {}, at_end: {}, props: {:?}}}",
+                position,
+                node.kind(),
+                layer.at_node_end,
+                layer.cursor.node_properties()
+            )?;
+        }
+        Ok(())
+    }
+}
+
 impl<'a> Layer<'a> {
     fn new(
         source: &'a [u8],