Error messages for removed DataModule hooks

src/pytorch_lightning/_graveyard/__init__.py

@@ -12,5 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import pytorch_lightning._graveyard.core
 import pytorch_lightning._graveyard.trainer
 import pytorch_lightning._graveyard.training_type  # noqa: F401

src/pytorch_lightning/_graveyard/core.py

@@ -0,0 +1,56 @@
+# 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 import LightningDataModule, LightningModule
+
+
+def _use_amp(_: LightningModule) -> None:
+    # Remove in v2.0.0
+    raise AttributeError(
+        "`LightningModule.use_amp` was deprecated in v1.6 and is no longer accessible as of v1.8."
+        " Please use `Trainer.amp_backend`.",
+    )
+
+
+def _use_amp_setter(_: LightningModule, __: bool) -> None:
+    # Remove in v2.0.0
+    raise AttributeError(
+        "`LightningModule.use_amp` was deprecated in v1.6 and is no longer accessible as of v1.8."
+        " Please use `Trainer.amp_backend`.",
+    )
+
+
+def _on_save_checkpoint(_: LightningDataModule, __: Any) -> None:
+    # Remove in v2.0.0
+    raise NotImplementedError(
+        "`LightningDataModule.on_save_checkpoint` was deprecated in v1.6 and removed in v1.8."
+        " Use `state_dict` instead."
+    )
+
+
+def _on_load_checkpoint(_: LightningDataModule, __: Any) -> None:
+    # Remove in v2.0.0
+    raise NotImplementedError(
+        "`LightningDataModule.on_load_checkpoint` was deprecated in v1.6 and removed in v1.8."
+        " Use `load_state_dict` instead."
+    )
+
+
+# Properties/Attributes
+LightningModule.use_amp = property(fget=_use_amp, fset=_use_amp_setter)
+
+# Methods
+LightningDataModule.on_save_checkpoint = _on_save_checkpoint
+LightningDataModule.on_load_checkpoint = _on_load_checkpoint

src/pytorch_lightning/trainer/configuration_validator.py

@@ -54,6 +54,8 @@ def verify_loop_configurations(trainer: "pl.Trainer") -> None:
     _check_on_epoch_start_end(model)
     # TODO: Delete this check in v2.0
     _check_on_pretrain_routine(model)
+    # TODO: Delete this check in v2.0
+    _check_unsupported_datamodule_hooks(trainer)
 
 
 def __verify_train_val_loop_configuration(trainer: "pl.Trainer", model: "pl.LightningModule") -> None:
@@ -253,3 +255,19 @@ def _check_deprecated_callback_hooks(trainer: "pl.Trainer") -> None:
                 raise RuntimeError(
                     f"The `Callback.{hook}` hook was removed in v1.8. Please use `Callback.on_fit_start` instead."
                 )
+
+
+def _check_unsupported_datamodule_hooks(trainer: "pl.Trainer") -> None:
+    datahook_selector = trainer._data_connector._datahook_selector
+    assert datahook_selector is not None
+
+    if is_overridden("on_save_checkpoint", datahook_selector.datamodule):
+        raise NotImplementedError(
+            "`LightningDataModule.on_save_checkpoint` was deprecated in v1.6 and removed in v1.8."
+            " Use `state_dict` instead."
+        )
+    if is_overridden("on_load_checkpoint", datahook_selector.datamodule):
+        raise NotImplementedError(
+            "`LightningDataModule.on_load_checkpoint` was deprecated in v1.6 and removed in v1.8."
+            " Use `load_state_dict` instead."
+        )

tests/tests_pytorch/graveyard/test_core.py

@@ -0,0 +1,55 @@
+# 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.
+import pytest
+
+from pytorch_lightning import Trainer
+from pytorch_lightning.demos.boring_classes import BoringDataModule, BoringModel
+
+
+def test_v2_0_0_unsupported_datamodule_on_save_load_checkpoint():
+    datamodule = BoringDataModule()
+    with pytest.raises(
+        NotImplementedError,
+        match="`LightningDataModule.on_save_checkpoint` was deprecated in v1.6 and removed in v1.8.",
+    ):
+        datamodule.on_save_checkpoint({})
+
+    with pytest.raises(
+        NotImplementedError,
+        match="`LightningDataModule.on_load_checkpoint` was deprecated in v1.6 and removed in v1.8.",
+    ):
+        datamodule.on_load_checkpoint({})
+
+    class OnSaveDataModule(BoringDataModule):
+        def on_save_checkpoint(self, checkpoint):
+            pass
+
+    class OnLoadDataModule(BoringDataModule):
+        def on_load_checkpoint(self, checkpoint):
+            pass
+
+    trainer = Trainer()
+    model = BoringModel()
+
+    with pytest.raises(
+        NotImplementedError,
+        match="`LightningDataModule.on_save_checkpoint` was deprecated in v1.6 and removed in v1.8.",
+    ):
+        trainer.fit(model, OnSaveDataModule())
+
+    with pytest.raises(
+        NotImplementedError,
+        match="`LightningDataModule.on_load_checkpoint` was deprecated in v1.6 and removed in v1.8.",
+    ):
+        trainer.fit(model, OnLoadDataModule())