Add deprecation path for the old LightningModule module (#12740)

CHANGELOG.md

@@ -108,7 +108,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Deprecated setting `LightningCLI(seed_everything_default=None)` in favor of `False` ([#12804](https://github.com/PyTorchLightning/pytorch-lightning/issues/12804)).
 
 
--
+- Deprecated `pytorch_lightning.core.lightning.LightningModule` in favor of `pytorch_lightning.core.module.LightningModule` ([#12740](https://github.com/PyTorchLightning/pytorch-lightning/pull/12740))
 
 
 -

pytorch_lightning/core/lightning.py

@@ -0,0 +1,27 @@
+# Copyright The PyTorch Lightning team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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 typing import Any
+
+from pytorch_lightning.core.module import LightningModule as NewLightningModule
+from pytorch_lightning.utilities import rank_zero_deprecation
+
+
+class LightningModule(NewLightningModule):
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        rank_zero_deprecation(
+            "pytorch_lightning.core.lightning.LightningModule has been deprecated in v1.7"
+            " and will be removed in v1.9."
+            " Use the equivalent class from the pytorch_lightning.core.module.LightningModule class instead."
+        )
+        super().__init__(*args, **kwargs)

tests/deprecated_api/test_remove_1-9.py

@@ -84,6 +84,16 @@ def test_lightning_logger_base_merge_dicts_deprecation_warning():
         logger_base.merge_dicts([d1, d2, d3], agg_funcs, dflt_func)
 
 
+def test_old_lightningmodule_path():
+    from pytorch_lightning.core.lightning import LightningModule
+
+    with pytest.deprecated_call(
+        match="pytorch_lightning.core.lightning.LightningModule has been deprecated in v1.7"
+        " and will be removed in v1.9."
+    ):
+        LightningModule()
+
+
 def test_lightningCLI_seed_everything_default_to_None_deprecation_warning():
     with mock.patch("sys.argv", ["any.py"]), pytest.deprecated_call(
         match="Setting `LightningCLI.seed_everything_default` to `None` is deprecated in v1.7 "