BUG: GH42866 DatetimeIndex de-serializing fails in PYTHONOPTIMIZE mode (#42871)

Author: GorAlexander

doc/source/whatsnew/v1.3.2.rst

@@ -33,6 +33,8 @@ Bug fixes
 - Bug in :meth:`pandas.read_excel` modifies the dtypes dictionary when reading a file with duplicate columns (:issue:`42462`)
 - 1D slices over extension types turn into N-dimensional slices over ExtensionArrays (:issue:`42430`)
 - :meth:`.Styler.hide_columns` now hides the index name header row as well as column headers (:issue:`42101`)
+- Bug in de-serializing datetime indexes in PYTHONOPTIMIZED mode (:issue:`42866`)
+-
 
 .. ---------------------------------------------------------------------------
 

pandas/core/indexes/datetimes.py

@@ -92,7 +92,8 @@ def _new_DatetimeIndex(cls, d):
  # These are already stored in our DatetimeArray; if they are
  # also in the pickle and don't match, we have a problem.
  if key in d:
- assert d.pop(key) == getattr(dta, key)
+ assert d[key] == getattr(dta, key)
+ d.pop(key)
  result = cls._simple_new(dta, **d)
  else:
  with warnings.catch_warnings():

pandas/tests/test_downstream.py

@@ -73,6 +73,21 @@ def test_oo_optimizable():
  subprocess.check_call([sys.executable, "-OO", "-c", "import pandas"])
 
 
+def test_oo_optimized_datetime_index_unpickle():
+ # GH 42866
+ subprocess.check_call(
+ [
+ sys.executable,
+ "-OO",
+ "-c",
+ (
+ "import pandas as pd, pickle; "
+ "pickle.loads(pickle.dumps(pd.date_range('2021-01-01', periods=1)))"
+ ),
+ ]
+ )
+
+
 @tm.network
 # Cython import warning
 @pytest.mark.filterwarnings("ignore:pandas.util.testing is deprecated")