[0-size Tensor No.91、308] Add 0-size Tensor support for inner

python/paddle/tensor/math.py

@@ -2869,15 +2869,26 @@ def inner(x: Tensor, y: Tensor, name: str | None = None) -> Tensor:
 
 
     """
+    xshape = x.shape
+    yshape = y.shape
     if in_dynamic_mode() and (x.size == 1 or y.size == 1):
         return multiply(x, y)
     else:
-        xshape = x.shape
-        yshape = y.shape
         dstshape = list(xshape[:-1]) + list(yshape[:-1])
-
-        nx = x.reshape((-1, xshape[-1]))
-        ny = y.reshape((-1, yshape[-1]))
+        if xshape[-1] == 0:  # If the last dimension is 0
+            if len(xshape) == 1:  # shape is [0]
+                nx = x.reshape((1, 0))
+            else:
+                nx = x.reshape((math.prod(xshape[:-1]), 0))
+        else:
+            nx = x.reshape((-1, xshape[-1]))
+        if yshape[-1] == 0:  # If the last dimension is 0
+            if len(yshape) == 1:  # shape is [0]
+                ny = y.reshape((1, 0))
+            else:
+                ny = y.reshape((math.prod(yshape[:-1]), 0))
+        else:
+            ny = y.reshape((-1, yshape[-1]))
 
         def __check_input(x, y):
             var_names = {'x': x, 'y': y}

test/legacy_test/test_inner.py

@@ -170,6 +170,32 @@ def test_errors_dynamic_case4(self):
         self.assertRaises(Exception, paddle.inner, x_data, y_data)
 
 
+class TestMultiplyApi_ZeroSize(unittest.TestCase):
+    def _test_case(self, x_shape, y_shape):
+        paddle.disable_static()
+        x_data = np.random.rand(*x_shape).astype(np.float64)
+        y_data = np.random.rand(*y_shape).astype(np.float64)
+        x = paddle.to_tensor(x_data)
+        y = paddle.to_tensor(y_data)
+        x.stop_gradient = False
+        y.stop_gradient = False
+        res = paddle.inner(x, y)
+        np.testing.assert_allclose(
+            res.numpy(), np.inner(x_data, y_data), rtol=1e-05
+        )
+        loss = paddle.sum(res)
+        loss.backward()
+        np.testing.assert_allclose(x.grad.shape, x.shape)
+
+    def test_case(self):
+        self._test_case([5, 10, 0], [2, 0])
+        self._test_case([0], [0])
+        self._test_case([0, 0], [1, 0])
+        self._test_case([0, 0], [0, 0])
+        self._test_case([0], [1, 0])
+        self._test_case([5, 1, 1], [1, 0, 1])
+
+
 if __name__ == '__main__':
     paddle.enable_static()
     unittest.main()