Add AttrsList::spans_iter and use it in Buffer::append

src/attrs.rs

@@ -306,7 +306,12 @@ impl AttrsList {
 
     /// Get the current attribute spans
     pub fn spans(&self) -> Vec<(&Range<usize>, &AttrsOwned)> {
-        self.spans.iter().collect()
+        self.spans_iter().collect()
+    }
+
+    /// Get an iterator over the current attribute spans
+    pub fn spans_iter(&self) -> impl Iterator<Item = (&Range<usize>, &AttrsOwned)> + '_ {
+        self.spans.iter()
     }
 
     /// Clear the current attribute spans

src/buffer_line.rs

@@ -144,7 +144,7 @@ impl BufferLine {
                 .add_span(len..len + other.text().len(), other.attrs_list.defaults());
         }
 
-        for (other_range, attrs) in other.attrs_list.spans() {
+        for (other_range, attrs) in other.attrs_list.spans_iter() {
             // Add previous attrs spans
             let range = other_range.start + len..other_range.end + len;
             self.attrs_list.add_span(range, attrs.as_attrs());