BUG: read_csv with custom date parser and na_filter=True results in ValueError

pandas/tests/io/parser/test_parse_dates.py

@@ -55,6 +55,40 @@ def test_separator_date_conflict(all_parsers):
     )
     tm.assert_frame_equal(df, expected)
 
+@pytest.fixtures(all_parsers)
+def test_read_csv_with_custom_date_parser(all_parsers):
+    # GH36111
+    def __custom_date_parser(time):
+        time = time.astype(np.float)
+        time = time.astype(np.int)  # convert float seconds to int type
+        return pd.to_timedelta(time, unit="s")
+    testdata = StringIO(
+        """time    e   n   h
+        41047.00	-98573.7297	871458.0640	389.0089
+        41048.00	-98573.7299	871458.0640	389.0089
+        41049.00	-98573.7300	871458.0642	389.0088
+        41050.00	-98573.7299	871458.0643	389.0088
+        41051.00	-98573.7302	871458.0640	389.0086
+            """
+    )
+    parser = all_parsers
+    result = parser.read_csv(
+        testdata,
+        delim_whitespace=True,
+        parse_dates=True,
+        date_parser=__custom_date_parser,
+        index_col="time",
+    )
+    expected = pd.DataFrame(
+        {
+            "e": [-98573.7297, -98573.7299, -98573.7300, -98573.7299, -98573.7302],
+            "n": [871458.0640, 871458.0640, 871458.0642, 871458.0643, 871458.0640],
+            "h": [389.0089, 389.0089, 389.0088, 389.0088, 389.0086],
+        },
+        index=[41047, 41048, 41049, 41050, 41051],
+    )
+    tm.assert_frame_equal(result, expected)
+
 
 @pytest.mark.parametrize("keep_date_col", [True, False])
 def test_multiple_date_col_custom(all_parsers, keep_date_col):