Remove the deprecated code in pl.core.mixins (#16424)

Author: carmocca

src/pytorch_lightning/CHANGELOG.md

@@ -67,6 +67,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
   * env_prefix
   * env_parse
 
+- Removed the deprecated code in `pl.core.mixins` ([#16424](https://github.com/Lightning-AI/lightning/pull/16424))
+
 - Removed the deprecated code in `pl.utilities.distributed` ([#16390](https://github.com/Lightning-AI/lightning/pull/16390))
 
 - Removed the deprecated code in `pl.utilities.apply_func` ([#16413](https://github.com/Lightning-AI/lightning/pull/16413))

src/pytorch_lightning/core/mixins/__init__.py

@@ -11,6 +11,4 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-from lightning_fabric.utilities.device_dtype_mixin import _DeviceDtypeModuleMixin  # noqa: F401
 from pytorch_lightning.core.mixins.hparams_mixin import HyperparametersMixin  # noqa: F401

src/pytorch_lightning/core/mixins/device_dtype_mixin.py

@@ -17,7 +17,6 @@
 from torch.utils.data import DataLoader
 
 from pytorch_lightning.accelerators.cpu import CPUAccelerator
-from pytorch_lightning.core.mixins.device_dtype_mixin import DeviceDtypeModuleMixin
 from pytorch_lightning.demos.boring_classes import RandomDataset
 from pytorch_lightning.strategies.utils import on_colab_kaggle
 from pytorch_lightning.utilities.cloud_io import atomic_save, get_filesystem, load
@@ -31,14 +30,6 @@ def test_v1_10_deprecated_on_colab_kaggle_func():
         on_colab_kaggle()
 
 
-def test_v1_10_deprecated_device_dtype_module_mixin():
-    class MyModule(DeviceDtypeModuleMixin):
-        pass
-
-    with pytest.deprecated_call(match="mixins.DeviceDtypeModuleMixin` has been deprecated in v1.8.0"):
-        MyModule()
-
-
 def test_v1_10_deprecated_cloud_io_utilities(tmpdir):
     with pytest.deprecated_call(match="cloud_io.atomic_save` has been deprecated in v1.8.0"):
         atomic_save({}, tmpdir / "atomic_save.ckpt")