CF: reference doesn't mean it's not null

Cython/Compiler/FlowControl.py

@@ -193,9 +193,11 @@ class ControlFlow(object):
     def mark_reference(self, node, entry):
         if self.block and self.is_tracked(entry):
             self.block.stats.append(NameReference(node, entry))
-            # Local variable is definitely bound after this reference
-            if not node.allow_null:
-                self.block.bounded.add(entry)
+            ## XXX: We don't track expression evaluation order so we can't use
+            ## XXX: successful reference as initialization sign.
+            ## # Local variable is definitely bound after this reference
+            ## if not node.allow_null:
+            ##     self.block.bounded.add(entry)
             self.entries.add(entry)
 
     def normalize(self):
@@ -548,9 +550,9 @@ def check_definitions(flow, compiler_directives):
                 references[stat.node] = stat.entry
                 stat.entry.cf_references.append(stat)
                 stat.node.cf_state.update(state)
-                if not stat.node.allow_null:
-                    i_state &= ~i_assmts.bit
-                # after successful read, the state is known to be initialised
+                ## if not stat.node.allow_null:
+                ##     i_state &= ~i_assmts.bit
+                ## # after successful read, the state is known to be initialised
                 state.discard(Uninitialized)
                 state.discard(Unknown)
                 for assmt in state:

tests/run/uninitialized.py

@@ -163,3 +163,17 @@ def test_try_finally_regression(c):
         return a
     finally:
         return a
+
+
+def test_expression_calculation_order_bug(a):
+    """
+    >>> test_expression_calculation_order_bug(False)
+    []
+    >>> test_expression_calculation_order_bug(True)
+    Traceback (most recent call last):
+    ...
+    UnboundLocalError: local variable 'b' referenced before assignment
+    """
+    if not a:
+        b = []
+    return (a or b) and (b or a)