Removed a redundant warning with ModelCheckpoint(monitor=None) callback

CHANGELOG.md

@@ -418,6 +418,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Removed `TrainerProperties` mixin and moved property definitions directly into `Trainer` ([#9495](https://github.com/PyTorchLightning/pytorch-lightning/pull/9495))
 
 
+- Removed a redundant warning with `ModelCheckpoint(monitor=None)` callback ([#9875](https://github.com/PyTorchLightning/pytorch-lightning/pull/9875))
+
+
 ### Fixed
 
 

pytorch_lightning/callbacks/model_checkpoint.py

@@ -147,7 +147,7 @@ class ModelCheckpoint(Callback):
 
     Raises:
         MisconfigurationException:
-            If ``save_top_k`` is neither ``None`` nor more than or equal to ``-1``,
+            If ``save_top_k`` is smaller than ``-1``,
             if ``monitor`` is ``None`` and ``save_top_k`` is none of ``None``, ``-1``, and ``0``, or
             if ``mode`` is none of ``"min"`` or ``"max"``.
         ValueError:
@@ -427,11 +427,7 @@ def __validate_init_configuration(self) -> None:
                     f"ModelCheckpoint(save_top_k={self.save_top_k}, monitor=None) is not a valid"
                     " configuration. No quantity for top_k to track."
                 )
-            if self.save_last:
-                rank_zero_warn(
-                    "ModelCheckpoint(save_last=True, save_top_k=None, monitor=None) is a redundant configuration."
-                    " You can save the last checkpoint with ModelCheckpoint(save_top_k=None, monitor=None)."
-                )
+
             if self.save_top_k == -1 and self.save_last:
                 rank_zero_info(
                     "ModelCheckpoint(save_last=True, save_top_k=-1, monitor=None)"

tests/checkpointing/test_model_checkpoint.py

@@ -516,15 +516,6 @@ def test_none_monitor_top_k(tmpdir):
     ModelCheckpoint(dirpath=tmpdir, save_top_k=1)
 
 
-def test_none_monitor_save_last(tmpdir):
-    """Test that a warning appears for save_last=True with monitor=None."""
-    with pytest.warns(UserWarning, match=r"ModelCheckpoint.*is a redundant.*"):
-        ModelCheckpoint(dirpath=tmpdir, save_last=True)
-    # These should not fail
-    ModelCheckpoint(dirpath=tmpdir, save_last=None)
-    ModelCheckpoint(dirpath=tmpdir, save_last=False)
-
-
 def test_invalid_every_n_epochs(tmpdir):
     """Make sure that a MisconfigurationException is raised for a negative every_n_epochs argument."""
     with pytest.raises(MisconfigurationException, match=r".*Must be >= 0"):