Backport PR #51538 on branch 2.0.x (BUG: Timedelta comparisons with very large pytimedeltas overflowing) (#52241)

Backport PR #51538: BUG: Timedelta comparisons with very large pytimedeltas overflowing Co-authored-by: jbrockmendel <jbrockmendel@gmail.com>

Author: meeseeksmachine

doc/source/whatsnew/v2.0.0.rst

@@ -1189,6 +1189,7 @@ Timedelta
 - Bug in :func:`to_timedelta` raising error when input has nullable dtype ``Float64`` (:issue:`48796`)
 - Bug in :class:`Timedelta` constructor incorrectly raising instead of returning ``NaT`` when given a ``np.timedelta64("nat")`` (:issue:`48898`)
 - Bug in :class:`Timedelta` constructor failing to raise when passed both a :class:`Timedelta` object and keywords (e.g. days, seconds) (:issue:`48898`)
+- Bug in :class:`Timedelta` comparisons with very large ``datetime.timedelta`` objects incorrect raising ``OutOfBoundsTimedelta`` (:issue:`49021`)
 
 Timezones
 ^^^^^^^^^

pandas/_libs/tslibs/timedeltas.pyx

@@ -4,6 +4,10 @@ import warnings
 cimport cython
 from cpython.object cimport (
  Py_EQ,
+ Py_GE,
+ Py_GT,
+ Py_LE,
+ Py_LT,
  Py_NE,
  PyObject,
  PyObject_RichCompare,
@@ -1150,8 +1154,27 @@ cdef class _Timedelta(timedelta):
  if isinstance(other, _Timedelta):
  ots = other
  elif is_any_td_scalar(other):
- ots = Timedelta(other)
- # TODO: watch out for overflows
+ try:
+ ots = Timedelta(other)
+ except OutOfBoundsTimedelta as err:
+ # GH#49021 pytimedelta.max overflows
+ if not PyDelta_Check(other):
+ # TODO: handle this case
+ raise
+ ltup = (self.days, self.seconds, self.microseconds, self.nanoseconds)
+ rtup = (other.days, other.seconds, other.microseconds, 0)
+ if op == Py_EQ:
+ return ltup == rtup
+ elif op == Py_NE:
+ return ltup != rtup
+ elif op == Py_LT:
+ return ltup < rtup
+ elif op == Py_LE:
+ return ltup <= rtup
+ elif op == Py_GT:
+ return ltup > rtup
+ elif op == Py_GE:
+ return ltup >= rtup
 
  elif other is NaT:
  return op == Py_NE

pandas/tests/scalar/timedelta/test_arithmetic.py

@@ -966,6 +966,70 @@ def test_td_op_timedelta_timedeltalike_array(self, op, arr):
 
 
 class TestTimedeltaComparison:
+ def test_compare_pytimedelta_bounds(self):
+ # GH#49021 don't overflow on comparison with very large pytimedeltas
+
+ for unit in ["ns", "us"]:
+ tdmax = Timedelta.max.as_unit(unit).max
+ tdmin = Timedelta.min.as_unit(unit).min
+
+ assert tdmax < timedelta.max
+ assert tdmax <= timedelta.max
+ assert not tdmax > timedelta.max
+ assert not tdmax >= timedelta.max
+ assert tdmax != timedelta.max
+ assert not tdmax == timedelta.max
+
+ assert tdmin > timedelta.min
+ assert tdmin >= timedelta.min
+ assert not tdmin < timedelta.min
+ assert not tdmin <= timedelta.min
+ assert tdmin != timedelta.min
+ assert not tdmin == timedelta.min
+
+ # But the "ms" and "s"-reso bounds extend pass pytimedelta
+ for unit in ["ms", "s"]:
+ tdmax = Timedelta.max.as_unit(unit).max
+ tdmin = Timedelta.min.as_unit(unit).min
+
+ assert tdmax > timedelta.max
+ assert tdmax >= timedelta.max
+ assert not tdmax < timedelta.max
+ assert not tdmax <= timedelta.max
+ assert tdmax != timedelta.max
+ assert not tdmax == timedelta.max
+
+ assert tdmin < timedelta.min
+ assert tdmin <= timedelta.min
+ assert not tdmin > timedelta.min
+ assert not tdmin >= timedelta.min
+ assert tdmin != timedelta.min
+ assert not tdmin == timedelta.min
+
+ def test_compare_pytimedelta_bounds2(self):
+ # a pytimedelta outside the microsecond bounds
+ pytd = timedelta(days=999999999, seconds=86399)
+ # NB: np.timedelta64(td, "s"") incorrectly overflows
+ td64 = np.timedelta64(pytd.days, "D") + np.timedelta64(pytd.seconds, "s")
+ td = Timedelta(td64)
+ assert td.days == pytd.days
+ assert td.seconds == pytd.seconds
+
+ assert td == pytd
+ assert not td != pytd
+ assert not td < pytd
+ assert not td > pytd
+ assert td <= pytd
+ assert td >= pytd
+
+ td2 = td - Timedelta(seconds=1).as_unit("s")
+ assert td2 != pytd
+ assert not td2 == pytd
+ assert td2 < pytd
+ assert td2 <= pytd
+ assert not td2 > pytd
+ assert not td2 >= pytd
+
  def test_compare_tick(self, tick_classes):
  cls = tick_classes