BUG: loc with empty multiindex raises exception (#38711)

Author: kasim95

pandas/tests/indexing/multiindex/test_getitem.py

@@ -260,3 +260,22 @@ def test_frame_mi_empty_slice():
         index=[0, 1], columns=MultiIndex(levels=[[1], [2]], codes=[[], []])
     )
     tm.assert_frame_equal(result, expected)
+
+
+def test_loc_empty_multiindex():
+    # GH#36936
+    arrays = [["a", "a", "b", "a"], ["a", "a", "b", "b"]]
+    index = MultiIndex.from_arrays(arrays, names=("idx1", "idx2"))
+    df = DataFrame([1, 2, 3, 4], index=index, columns=["value"])
+
+    # loc on empty multiindex == loc with False mask
+    empty_multiindex = df.loc[df.loc[:, "value"] == 0, :].index
+    result = df.loc[empty_multiindex, :]
+    expected = df.loc[[False] * len(df.index), :]
+    tm.assert_frame_equal(result, expected)
+
+    # replacing value with loc on empty multiindex
+    df.loc[df.loc[df.loc[:, "value"] == 0].index, "value"] = 5
+    result = df
+    expected = DataFrame([1, 2, 3, 4], index=index, columns=["value"])
+    tm.assert_frame_equal(result, expected)