Clarify error message related to expected kern_shape in GpuDnnConvDesc…

theano/gpuarray/dnn.py

@@ -386,7 +386,7 @@ class GpuDnnConvDesc(COp):
 
     def make_node(self, kern_shape):
         if kern_shape.type.ndim != 1 or kern_shape.type.dtype != 'int64':
-            raise TypeError('kern must be 1D shape tensor')
+            raise TypeError('kern must be an int64 1D shape tensor')
 
         node = Apply(self, [kern_shape],
                      [CDataType("cudnnConvolutionDescriptor_t",

theano/gpuarray/tests/test_dnn.py

@@ -657,7 +657,7 @@ class TestDnnInferShapes(utt.InferShapeTester):
         )
 
         kerns_vals = np.zeros(kerns_shape, dtype=theano.config.floatX)
-        kerns_shape = theano.shared(np.asarray(kerns_shape))
+        kerns_shape = theano.shared(np.asarray(kerns_shape, dtype=np.int64))
         desc = dnn.GpuDnnConvDesc(
             border_mode=border_mode,
             subsample=subsample,