fix for-in loop variable inference after enabling list/tuple item type inference

Cython/Compiler/ExprNodes.py

@@ -2489,9 +2489,11 @@ class NextNode(AtomicExprNode):
             return item_type
         else:
             # Avoid duplication of complicated logic.
-            fake_index_node = IndexNode(self.pos,
-                                        base=self.iterator.sequence,
-                                        index=IntNode(self.pos, value='0'))
+            fake_index_node = IndexNode(
+                self.pos,
+                base=self.iterator.sequence,
+                index=IntNode(self.pos, value='PY_SSIZE_T_MAX',
+                              type=PyrexTypes.c_py_ssize_t_type))
             return fake_index_node.infer_type(env)
 
     def analyse_types(self, env):

Cython/Compiler/TypeInference.py

@@ -136,8 +136,9 @@ class MarkParallelAssignments(EnvTransform):
             # object type when the base type cannot be handled.
             self.mark_assignment(target, ExprNodes.IndexNode(
                 node.pos,
-                base = sequence,
-                index = ExprNodes.IntNode(node.pos, value = '0')))
+                base=sequence,
+                index=ExprNodes.IntNode(target.pos, value='PY_SSIZE_T_MAX',
+                                        type=PyrexTypes.c_py_ssize_t_type)))
 
         self.visitchildren(node)
         return node

tests/run/listcomp.pyx

@@ -46,6 +46,13 @@ def inferred_type():
     """
     print [cython.typeof(obj) for obj in [A(), A(), A()]]
 
+def not_inferred_type():
+    """
+    >>> not_inferred_type()
+    ['Python object', 'Python object', 'Python object']
+    """
+    print [cython.typeof(obj) for obj in [1, A(), 'abc']]
+
 def iterdict():
     """
     >>> iterdict()