Issue 26279: time.strptime does not properly convert out-of-bounds values (original) (raw)

There seems to be a bug in the time library when performing the following conversion:

""" In [8]: mytime=time.strptime(str([2015, 53, 0]), '[%Y, %U, %w]')

In [9]: mytime Out[9]: time.struct_time(tm_year=2016, tm_mon=1, tm_mday=3, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=6, tm_yday=368, tm_isdst=-1)

In [10]: time.strftime('%Y %U', mytime)

ValueError Traceback (most recent call last) in () ----> 1 time.strftime('%Y %U', mytime)

ValueError: day of year out of range """

As you can observe, tm_yday got a value of 368 instead of 3. It seems that the C function is not properly subtracting 365 or 366 days when converting from week 53 of a particular year which, according to ISO 8601 [1] and per python documentation [2]. Documentation explicitly says that: "The first week of the year is the week with the year's first Thursday in it".

[1] https://en.wikipedia.org/wiki/ISO_8601#Week_dates [2] https://docs.python.org/2/library/time.html