added UserWarnings if max_epochs not set in the Trainer class

docs/source/common/trainer.rst

@@ -900,7 +900,7 @@ Stop training once this number of epochs is reached
     # default used by the Trainer
     trainer = Trainer(max_epochs=1000)
 
-If both ``max_epochs`` and ``max_steps`` aren't specified, ``max_epochs`` will default to ``1000``.
+If both ``max_epochs`` and ``max_steps`` aren't specified, ``max_epochs`` will default to ``1000`` and a ``UserWarning`` will be displayed stating the ``max_epochs`` is not set and defaulted to ``1000``.
 To enable infinite training, set ``max_epochs = -1``.
 
 min_epochs

pytorch_lightning/trainer/trainer.py

@@ -444,6 +444,12 @@ def __init__(
         self.signal_connector = SignalConnector(self)
         self.tuner = Tuner(self)
 
+        # UserWarning for max_epochs if not set
+
+        warnings.warn("max_epochs not set, defaulted to 1000 epochs until stop.") if self.max_epochs is None else print(
+            f"max epochs set to {self.max_epochs}"
+        )
+
         fit_loop = FitLoop(
             min_epochs=(1 if (min_epochs is None and min_steps is None and max_time is None) else min_epochs),
             max_epochs=(