testing infer_shape: Op Default

theano/tensor/basic.py

@@ -3410,6 +3410,14 @@ class Default(gof.Op):
         else:
             out[0] = x
 
+    def infer_shape(self, node, in_shapes):
+        if node.inputs[0] is None:
+            out_shape = in_shapes[1]
+        else:
+            out_shape = in_shapes[0]
+        return [out_shape]
+
+
 default = Default()
 setdefault = default  # legacy
 

theano/tensor/tests/test_basic.py

@@ -34,7 +34,7 @@ from theano.tensor import (_shared, wvector, bvector, autocast_float_as,
         get_constant_value, ivector, reshape, scalar_from_tensor, scal,
         iscalars, arange,  dscalars, fvector, imatrix, numeric_grad,
         opt, ComplexError, TensorDot, lvector, true_div, max, min, Split, roll,
-        tile, patternbroadcast, Eye, Shape)
+        tile, patternbroadcast, Eye, Shape, Default)
 from theano.tests import unittest_tools as utt
 from theano.printing import debugprint
 
@@ -6083,6 +6083,12 @@ class TestInferShape(utt.InferShapeTester):
                                 [Shape()(adtens)],
                                 [adtens_val], (opt.MakeVector, Shape))
 
+        # Default
+        self._compile_and_check([admat, bdmat],
+                                [Default()(admat, bdmat)],
+                                [admat_val, bdmat_val], (Default))
+
+
 if __name__ == '__main__':
 
     t = TestInferShape('setUp')