BUG: ignore errors for invalid dates in to_datetime() with errors=coerce (#25512)

pandas/core/tools/datetimes.py

@@ -775,21 +775,21 @@ def calc_with_mask(carg, mask):
  # try intlike / strings that are ints
  try:
  return calc(arg.astype(np.int64))
- except ValueError:
+ except (ValueError, OverflowError):
  pass
 
  # a float with actual np.nan
  try:
  carg = arg.astype(np.float64)
  return calc_with_mask(carg, notna(carg))
- except ValueError:
+ except (ValueError, OverflowError):
  pass
 
  # string with NaN-like
  try:
  mask = ~algorithms.isin(arg, list(tslib.nat_strings))
  return calc_with_mask(arg, mask)
- except ValueError:
+ except (ValueError, OverflowError):
  pass
 
  return None

pandas/tests/indexes/datetimes/test_tools.py

@@ -83,6 +83,35 @@ def test_to_datetime_format_YYYYMMDD(self, cache):
  result = to_datetime(s, format='%Y%m%d', cache=cache)
  assert_series_equal(result, expected)
 
+ # GH 25512
+ # NaN before strings with invalid date values, errors=coerce
+ s = Series(['19801222', np.nan, '20010012', '10019999'])
+ result = pd.to_datetime(s, format='%Y%m%d', errors='coerce',
+ cache=cache)
+ expected = Series([Timestamp('19801222'), np.nan, np.nan, np.nan])
+ tm.assert_series_equal(result, expected)
+
+ # NaN after strings with invalid date values, errors=coerce
+ s = Series(['19801222', '20010012', '10019999', np.nan])
+ result = pd.to_datetime(s, format='%Y%m%d', errors='coerce',
+ cache=cache)
+ expected = Series([Timestamp('19801222'), np.nan, np.nan, np.nan])
+ tm.assert_series_equal(result, expected)
+
+ # NaN before integers with invalid date values, errors=coerce
+ s = Series([20190813, np.nan, 20010012, 20019999])
+ result = pd.to_datetime(s, format='%Y%m%d', errors='coerce',
+ cache=cache)
+ expected = Series([Timestamp('20190813'), np.nan, np.nan, np.nan])
+ tm.assert_series_equal(result, expected)
+
+ # NaN after integers with invalid date values, errors=coerce
+ s = Series([20190813, 20010012, np.nan, 20019999])
+ result = pd.to_datetime(s, format='%Y%m%d', errors='coerce',
+ cache=cache)
+ expected = Series([Timestamp('20190813'), np.nan, np.nan, np.nan])
+ tm.assert_series_equal(result, expected)
+
  # coercion
  # GH 7930
  s = Series([20121231, 20141231, 99991231])