comment

diff --git a/Cython/Compiler/Optimize.py b/Cython/Compiler/Optimize.py
index c6500bbe1969c4af8853d992c87bbd79c99dc3c6..8c97b0743d45231578a829d89ef9062ec347d5b5 100644 (file)
--- a/Cython/Compiler/Optimize.py
+++ b/Cython/Compiler/Optimize.py
@@ -616,6 +616,9 @@ class DropRefcountingTransform(Visitor.VisitorTransform):
     visit_Node = Visitor.VisitorTransform.recurse_to_children
 
     def visit_ParallelAssignmentNode(self, node):
+        """
+        Parallel swap assignments like 'a,b = b,a' are safe.
+        """
         left_names, right_names = [], []
         left_indices, right_indices = [], []
         temps = []