Fix import path of inherited classmethod not resolving correctly

CHANGELOG.rst

@@ -31,6 +31,9 @@ Fixed
 - ``dump`` failing when a link target requires serialization and
   ``skip_link_targets=False`` (`#542
   <https://github.com/omni-us/jsonargparse/pull/542>`__).
+- Import path of inherited classmethod not resolving correctly (`lightning#19863
+  comment
+  <https://github.com/Lightning-AI/pytorch-lightning/discussions/19863#discussioncomment-10010226>`__).
 
 
 v4.31.0 (2024-06-27)

jsonargparse/_util.py

@@ -216,8 +216,12 @@ def get_import_path(value: Any) -> Optional[str]:
     """Returns the shortest dot import path for the given object."""
     path = None
     value = get_generic_origin(value)
-    module_path = getattr(value, "__module__", None)
-    qualname = getattr(value, "__qualname__", "")
+    if hasattr(value, "__self__") and inspect.isclass(value.__self__) and inspect.ismethod(value):
+        module_path = getattr(value.__self__, "__module__", None)
+        qualname = f"{value.__self__.__name__}.{value.__name__}"
+    else:
+        module_path = getattr(value, "__module__", None)
+        qualname = getattr(value, "__qualname__", "")
 
     if module_path is None:
         path = unresolvable_import_paths.get(value)
@@ -244,7 +248,7 @@ def get_import_path(value: Any) -> Optional[str]:
                 if getattr(module, attr, None) is value:
                     path = module_path + "." + attr
                     break
-                elif getattr(obj, attr, None) is value:
+                elif getattr(obj, attr, None) == value:
                     path = module_path + "." + qualname
                     break
             elif getattr(module, qualname, None) is value:

jsonargparse_tests/test_util.py

@@ -565,6 +565,23 @@ def test_get_import_path_static_method_shorthand():
     assert get_import_path(static_method) == f"{__name__}.static_method"
 
 
+class ParentClassmethod:
+    __module__ = "jsonargparse_tests"
+
+    @classmethod
+    def class_method(cls):
+        pass
+
+
+class ChildClassmethod(ParentClassmethod):
+    pass
+
+
+def test_get_import_path_classpath_inheritance():
+    assert get_import_path(ParentClassmethod.class_method) == "jsonargparse_tests.ParentClassmethod.class_method"
+    assert get_import_path(ChildClassmethod.class_method) == f"{__name__}.ChildClassmethod.class_method"
+
+
 def unresolvable_import():
     pass