Warn about deprecated connections that are not removed.

python/lsst/pipe/base/connections.py

@@ -38,6 +38,7 @@
 import dataclasses
 import itertools
 import string
+import warnings
 from collections import UserDict
 from collections.abc import Collection, Generator, Iterable, Mapping, Sequence, Set
 from dataclasses import dataclass
@@ -361,6 +362,12 @@ def __call__(cls, *, config: PipelineTaskConfig | None = None) -> PipelineTaskCo
         instance._allConnections.clear()
         instance._allConnections.update(updated_all_connections)
 
+        for obj in instance._allConnections.values():
+            if obj.deprecated is not None:
+                warnings.warn(
+                    obj.deprecated, FutureWarning, stacklevel=find_outside_stacklevel("lsst.pipe.base")
+                )
+
         # Freeze the connection instance dimensions now.  This at odds with the
         # type annotation, which says [mutable] `set`, just like the connection
         # type attributes (e.g. `inputs`, `outputs`, etc.), though MyPy can't

tests/test_connections.py

@@ -23,6 +23,7 @@
 """
 
 import unittest
+import warnings
 
 import lsst.pipe.base as pipeBase
 import lsst.utils.tests
@@ -194,13 +195,26 @@ class TestConnections(pipeBase.PipelineTaskConnections, dimensions=self.test_dim
                 deprecated="Deprecated in v50000, will be removed after v50001.",
             )
 
+            def __init__(self, config):
+                if config.drop_input1:
+                    del self.input1
+
         class TestConfig(pipeBase.PipelineTaskConfig, pipelineConnections=TestConnections):
-            pass
+            drop_input1 = Field("Remove the 'input1' connection if True", dtype=bool, default=False)
 
         config = TestConfig()
         with self.assertWarns(FutureWarning):
             config.connections.input1 = "some_other_dataset_type"
 
+        with self.assertWarns(FutureWarning):
+            TestConnections(config=config)
+
+        config.drop_input1 = True
+
+        with warnings.catch_warnings():
+            warnings.simplefilter("error", FutureWarning)
+            TestConnections(config=config)
+
 
 class MyMemoryTestCase(lsst.utils.tests.MemoryTestCase):
     pass