fix gh-883. Fix a crash introduced in the trunk for reshape([-1])

theano/tensor/basic.py

@@ -5391,11 +5391,13 @@ class Reshape(Op):
             requ = list(requ.data)
             requ_part = [ele for ele in requ if ele != -1]
             crit = len(requ) - len(requ_part)
-            if crit == 1:
-                missing = numpy.prod(ishapes[0]) / numpy.prod(requ_part)
+            if crit == 1 and len(requ_part) > 0:
+                missing = mul(*ishapes[0]) / mul(*requ_part)
                 for i, ele in enumerate(requ):
                     if ele == -1:
                         requ[i] = missing
+            elif crit == 1:  # we reshape to -1
+                requ = [mul(*ishapes[0])]
             elif crit > 1:
                 raise ValueError('shape argument to Reshape.perform'
                     ' must have at most one entry equal to -1')

theano/tensor/tests/test_basic.py

@@ -6686,8 +6686,17 @@ class TestInferShape(utt.InferShapeTester):
         # (non-constant) input shape
         admat = dmatrix()
         aivec = ivector()
-        ndim = 2
+        ndim = 1
         admat_val = rand(3, 4)
+        self._compile_and_check([admat],
+                                [Reshape(ndim)(admat, [12])],
+                                [admat_val], Reshape)
+
+        self._compile_and_check([admat],
+                                [Reshape(ndim)(admat, [-1])],
+                                [admat_val], Reshape)
+
+        ndim = 2
         self._compile_and_check([admat],
                                 [Reshape(ndim)(admat, [4, 3])],
                                 [admat_val], Reshape)
@@ -6696,6 +6705,17 @@ class TestInferShape(utt.InferShapeTester):
                                 [Reshape(ndim)(admat, [4, -1])],
                                 [admat_val], Reshape)
 
+        self._compile_and_check([admat],
+                                [Reshape(ndim)(admat, [3, -1])],
+                                [admat_val], Reshape)
+
+        self._compile_and_check([admat],
+                                [Reshape(ndim)(admat, [-1, 3])],
+                                [admat_val], Reshape)
+        self._compile_and_check([admat],
+                                [Reshape(ndim)(admat, [-1, 4])],
+                                [admat_val], Reshape)
+
         # enable when infer_shape is generalized:
         # self._compile_and_check([admat, aivec],
         #                        [Reshape(ndim)(admat, aivec)],