apply flatten-in-list transform also to literal sets

Cython/Compiler/Optimize.py

@@ -591,7 +591,9 @@ class FlattenInListTransform(Visitor.VisitorTransform, SkipDeclarations):
         else:
             return node
 
-        if not isinstance(node.operand2, (ExprNodes.TupleNode, ExprNodes.ListNode)):
+        if not isinstance(node.operand2, (ExprNodes.TupleNode,
+                                          ExprNodes.ListNode,
+                                          ExprNodes.SetNode)):
             return node
 
         args = node.operand2.args

tests/run/inop.pyx

@@ -52,16 +52,36 @@ def k(a):
     cdef int result = a in [1,2,3,4]
     return result
 
-def m(int a):
+def m_list(int a):
     """
-    >>> m(2)
+    >>> m_list(2)
     1
-    >>> m(5)
+    >>> m_list(5)
     0
     """
     cdef int result = a in [1,2,3,4]
     return result
 
+def m_tuple(int a):
+    """
+    >>> m_tuple(2)
+    1
+    >>> m_tuple(5)
+    0
+    """
+    cdef int result = a in (1,2,3,4)
+    return result
+
+def m_set(int a):
+    """
+    >>> m_set(2)
+    1
+    >>> m_set(5)
+    0
+    """
+    cdef int result = a in {1,2,3,4}
+    return result
+
 def n(a):
     """
     >>> n('d *')