Add infer_shape to Rebroadcast and test it.

theano/tensor/basic.py

@@ -3289,6 +3289,8 @@ class Rebroadcast(Op):
         gz, = grads
         # restore the broadcasting pattern of the input
         return Rebroadcast(*[(axis, x.type.broadcastable[axis]) for axis, value in self.axis.iteritems()])(gz),
+    def infer_shape(self, node, ishapes):
+        return ishapes
 
 def addbroadcast(x, *axes):
     """

theano/tensor/tests/test_basic.py

@@ -4156,6 +4156,18 @@ class test_broadcast(unittest.TestCase):
         assert addbroadcast(unbroadcast(x,1),0).owner.inputs[0] is x
         assert addbroadcast(unbroadcast(x,0),0) is x
 
+    def test_infer_shape(self):
+        x = matrix()
+        y = addbroadcast(x,0)
+        f = theano.function([x], y.shape)
+        f(numpy.zeros((1,5)))
+        topo = f.maker.env.toposort()
+        if theano.config.mode != 'FAST_COMPILE':
+            assert len(topo) == 3
+            assert isinstance(topo[0].op, opt.Shape_i)
+            assert isinstance(topo[1].op, opt.Shape_i)
+            assert isinstance(topo[2].op, opt.MakeVector)
+
 def test_mod():
     """
     We add this test as not all language and C implementation give the same