Bug report

Bug description

Python/pytime.c converts a Python number of seconds to a PyTime_t
(a 64-bit nanosecond count). The two conversion paths report an overflow
with different messages:

• the integer path, pytime_from_object(), calls pytime_overflow() →
  "timestamp too large to convert to C PyTime_t";
• the float path, pytime_from_double() (Python/pytime.c:639), calls
  pytime_time_t_overflow() → "timestamp out of range for platform time_t".

But pytime_from_double() does not convert to time_t at all — it converts
to PyTime_t. The float path names the wrong type, and disagrees with the
integer path for the same conceptual overflow.

It is user-visible through any API that accepts a float number of seconds,
e.g. time.sleep():

>>> import time
>>> time.sleep(2.0 ** 63)      # float path
OverflowError: timestamp out of range for platform time_t
>>> time.sleep(2 ** 63)        # integer path
OverflowError: timestamp too large to convert to C PyTime_t

The message is also wrong in fact, not only in type: PyTime_t saturates at
roughly 292 years (int64 nanoseconds), whereas 64-bit time_t spans far
longer — so time.sleep(1e10) (~317 years) overflows PyTime_t while being
comfortably within time_t range. The reported time_t limit was never the
actual constraint.

Fix

pytime_from_double() should call pytime_overflow(), the same helper the
integer path already uses, so both report the PyTime_t overflow:

    if (!((double)PyTime_MIN <= d && d < -(double)PyTime_MIN)) {
        pytime_overflow();
        *tp = 0;
        return -1;
    }

This is a one-line change; the correct helper already exists in the same file.

CPython versions

main (3.16). The float path has used pytime_time_t_overflow() since the
pytime_from_double() helper was introduced.

Linked PRs

• gh-152849: Fix OverflowError message for out-of-range float timestamps #152850
• [3.13] gh-152849: Fix OverflowError message for out-of-range timestamps in the time module (GH-152850) #153207
• [3.14] gh-152849: Fix OverflowError message for out-of-range timestamps in the time module (GH-152850) #153208
• [3.15] gh-152849: Fix OverflowError message for out-of-range timestamps in the time module (GH-152850) #153209