dateutil: correct default for Ymd in parsedate

The code uses `0` for the default value of Ymd (year, month, and day), which
seems suboptimal. For example, these will fail to parse:

  dateutil.parsedate('2000', formats=dateutil.extendeddateformats)
  dateutil.parsedate('Jan 2000', formats=dateutil.extendeddateformats)

Fix it by providing sane defaults (1 instead of 0) for year, month, and day.

The suboptimal behavior was introduced by 91bc001a592 (2010-12-29,
"date: fix matching of underspecified date ranges"), which does not seem to
justify the current behavior.

Note end-users should not notice the subtle issue, because there are no formats
in `defaultdateformats` that allow an explicit year with omitted month, or an
explicit month with omitted day.

Differential Revision: https://phab.mercurial-scm.org/D7520

mercurial/utils/dateutil.py

@@ -1,351 +1,354 b''
 # util.py - Mercurial utility functions relative to dates
 #
 #  Copyright 2018 Boris Feld <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import, print_function
 
 import calendar
 import datetime
 import time
 
 from ..i18n import _
 from .. import (
     encoding,
     error,
     pycompat,
 )
 
 # used by parsedate
 defaultdateformats = (
     b'%Y-%m-%dT%H:%M:%S',  # the 'real' ISO8601
     b'%Y-%m-%dT%H:%M',  #   without seconds
     b'%Y-%m-%dT%H%M%S',  # another awful but legal variant without :
     b'%Y-%m-%dT%H%M',  #   without seconds
     b'%Y-%m-%d %H:%M:%S',  # our common legal variant
     b'%Y-%m-%d %H:%M',  #   without seconds
     b'%Y-%m-%d %H%M%S',  # without :
     b'%Y-%m-%d %H%M',  #   without seconds
     b'%Y-%m-%d %I:%M:%S%p',
     b'%Y-%m-%d %H:%M',
     b'%Y-%m-%d %I:%M%p',
     b'%Y-%m-%d',
     b'%m-%d',
     b'%m/%d',
     b'%m/%d/%y',
     b'%m/%d/%Y',
     b'%a %b %d %H:%M:%S %Y',
     b'%a %b %d %I:%M:%S%p %Y',
     b'%a, %d %b %Y %H:%M:%S',  #  GNU coreutils "/bin/date --rfc-2822"
     b'%b %d %H:%M:%S %Y',
     b'%b %d %I:%M:%S%p %Y',
     b'%b %d %H:%M:%S',
     b'%b %d %I:%M:%S%p',
     b'%b %d %H:%M',
     b'%b %d %I:%M%p',
     b'%b %d %Y',
     b'%b %d',
     b'%H:%M:%S',
     b'%I:%M:%S%p',
     b'%H:%M',
     b'%I:%M%p',
 )
 
 extendeddateformats = defaultdateformats + (b"%Y", b"%Y-%m", b"%b", b"%b %Y",)
 
 
 def makedate(timestamp=None):
     '''Return a unix timestamp (or the current time) as a (unixtime,
     offset) tuple based off the local timezone.'''
     if timestamp is None:
         timestamp = time.time()
     if timestamp < 0:
         hint = _(b"check your clock")
         raise error.Abort(_(b"negative timestamp: %d") % timestamp, hint=hint)
     delta = datetime.datetime.utcfromtimestamp(
         timestamp
     ) - datetime.datetime.fromtimestamp(timestamp)
     tz = delta.days * 86400 + delta.seconds
     return timestamp, tz
 
 
 def datestr(date=None, format=b'%a %b %d %H:%M:%S %Y %1%2'):
     """represent a (unixtime, offset) tuple as a localized time.
     unixtime is seconds since the epoch, and offset is the time zone's
     number of seconds away from UTC.
 
     >>> datestr((0, 0))
     'Thu Jan 01 00:00:00 1970 +0000'
     >>> datestr((42, 0))
     'Thu Jan 01 00:00:42 1970 +0000'
     >>> datestr((-42, 0))
     'Wed Dec 31 23:59:18 1969 +0000'
     >>> datestr((0x7fffffff, 0))
     'Tue Jan 19 03:14:07 2038 +0000'
     >>> datestr((-0x80000000, 0))
     'Fri Dec 13 20:45:52 1901 +0000'
     """
     t, tz = date or makedate()
     if b"%1" in format or b"%2" in format or b"%z" in format:
         sign = (tz > 0) and b"-" or b"+"
         minutes = abs(tz) // 60
         q, r = divmod(minutes, 60)
         format = format.replace(b"%z", b"%1%2")
         format = format.replace(b"%1", b"%c%02d" % (sign, q))
         format = format.replace(b"%2", b"%02d" % r)
     d = t - tz
     if d > 0x7FFFFFFF:
         d = 0x7FFFFFFF
     elif d < -0x80000000:
         d = -0x80000000
     # Never use time.gmtime() and datetime.datetime.fromtimestamp()
     # because they use the gmtime() system call which is buggy on Windows
     # for negative values.
     t = datetime.datetime(1970, 1, 1) + datetime.timedelta(seconds=d)
     s = encoding.strtolocal(t.strftime(encoding.strfromlocal(format)))
     return s
 
 
 def shortdate(date=None):
     """turn (timestamp, tzoff) tuple into iso 8631 date."""
     return datestr(date, format=b'%Y-%m-%d')
 
 
 def parsetimezone(s):
     """find a trailing timezone, if any, in string, and return a
        (offset, remainder) pair"""
     s = pycompat.bytestr(s)
 
     if s.endswith(b"GMT") or s.endswith(b"UTC"):
         return 0, s[:-3].rstrip()
 
     # Unix-style timezones [+-]hhmm
     if len(s) >= 5 and s[-5] in b"+-" and s[-4:].isdigit():
         sign = (s[-5] == b"+") and 1 or -1
         hours = int(s[-4:-2])
         minutes = int(s[-2:])
         return -sign * (hours * 60 + minutes) * 60, s[:-5].rstrip()
 
     # ISO8601 trailing Z
     if s.endswith(b"Z") and s[-2:-1].isdigit():
         return 0, s[:-1]
 
     # ISO8601-style [+-]hh:mm
     if (
         len(s) >= 6
         and s[-6] in b"+-"
         and s[-3] == b":"
         and s[-5:-3].isdigit()
         and s[-2:].isdigit()
     ):
         sign = (s[-6] == b"+") and 1 or -1
         hours = int(s[-5:-3])
         minutes = int(s[-2:])
         return -sign * (hours * 60 + minutes) * 60, s[:-6]
 
     return None, s
 
 
 def strdate(string, format, defaults=None):
     """parse a localized time string and return a (unixtime, offset) tuple.
     if the string cannot be parsed, ValueError is raised."""
     if defaults is None:
         defaults = {}
 
     # NOTE: unixtime = localunixtime + offset
     offset, date = parsetimezone(string)
 
     # add missing elements from defaults
     usenow = False  # default to using biased defaults
     for part in (
         b"S",
         b"M",
         b"HI",
         b"d",
         b"mb",
         b"yY",
     ):  # decreasing specificity
         part = pycompat.bytestr(part)
         found = [True for p in part if (b"%" + p) in format]
         if not found:
             date += b"@" + defaults[part][usenow]
             format += b"@%" + part[0]
         else:
             # We've found a specific time element, less specific time
             # elements are relative to today
             usenow = True
 
     timetuple = time.strptime(
         encoding.strfromlocal(date), encoding.strfromlocal(format)
     )
     localunixtime = int(calendar.timegm(timetuple))
     if offset is None:
         # local timezone
         unixtime = int(time.mktime(timetuple))
         offset = unixtime - localunixtime
     else:
         unixtime = localunixtime + offset
     return unixtime, offset
 
 
 def parsedate(date, formats=None, bias=None):
     """parse a localized date/time and return a (unixtime, offset) tuple.
 
     The date may be a "unixtime offset" string or in one of the specified
     formats. If the date already is a (unixtime, offset) tuple, it is returned.
 
     >>> parsedate(b' today ') == parsedate(
     ...     datetime.date.today().strftime('%b %d').encode('ascii'))
     True
     >>> parsedate(b'yesterday ') == parsedate(
     ...     (datetime.date.today() - datetime.timedelta(days=1)
     ...      ).strftime('%b %d').encode('ascii'))
     True
     >>> now, tz = makedate()
     >>> strnow, strtz = parsedate(b'now')
     >>> (strnow - now) < 1
     True
     >>> tz == strtz
     True
+    >>> parsedate(b'2000 UTC', formats=extendeddateformats)
+    (946684800, 0)
     """
     if bias is None:
         bias = {}
     if not date:
         return 0, 0
     if isinstance(date, tuple) and len(date) == 2:
         return date
     if not formats:
         formats = defaultdateformats
     date = date.strip()
 
     if date == b'now' or date == _(b'now'):
         return makedate()
     if date == b'today' or date == _(b'today'):
         date = datetime.date.today().strftime('%b %d')
         date = encoding.strtolocal(date)
     elif date == b'yesterday' or date == _(b'yesterday'):
         date = (datetime.date.today() - datetime.timedelta(days=1)).strftime(
             r'%b %d'
         )
         date = encoding.strtolocal(date)
 
     try:
         when, offset = map(int, date.split(b' '))
     except ValueError:
         # fill out defaults
         now = makedate()
         defaults = {}
         for part in (b"d", b"mb", b"yY", b"HI", b"M", b"S"):
             # this piece is for rounding the specific end of unknowns
             b = bias.get(part)
             if b is None:
                 if part[0:1] in b"HMS":
                     b = b"00"
                 else:
-                    b = b"0"
+                    # year, month, and day start from 1
+                    b = b"1"
 
             # this piece is for matching the generic end to today's date
             n = datestr(now, b"%" + part[0:1])
 
             defaults[part] = (b, n)
 
         for format in formats:
             try:
                 when, offset = strdate(date, format, defaults)
             except (ValueError, OverflowError):
                 pass
             else:
                 break
         else:
             raise error.ParseError(
                 _(b'invalid date: %r') % pycompat.bytestr(date)
             )
     # validate explicit (probably user-specified) date and
     # time zone offset. values must fit in signed 32 bits for
     # current 32-bit linux runtimes. timezones go from UTC-12
     # to UTC+14
     if when < -0x80000000 or when > 0x7FFFFFFF:
         raise error.ParseError(_(b'date exceeds 32 bits: %d') % when)
     if offset < -50400 or offset > 43200:
         raise error.ParseError(_(b'impossible time zone offset: %d') % offset)
     return when, offset
 
 
 def matchdate(date):
     """Return a function that matches a given date match specifier
 
     Formats include:
 
     '{date}' match a given date to the accuracy provided
 
     '<{date}' on or before a given date
 
     '>{date}' on or after a given date
 
     >>> p1 = parsedate(b"10:29:59")
     >>> p2 = parsedate(b"10:30:00")
     >>> p3 = parsedate(b"10:30:59")
     >>> p4 = parsedate(b"10:31:00")
     >>> p5 = parsedate(b"Sep 15 10:30:00 1999")
     >>> f = matchdate(b"10:30")
     >>> f(p1[0])
     False
     >>> f(p2[0])
     True
     >>> f(p3[0])
     True
     >>> f(p4[0])
     False
     >>> f(p5[0])
     False
     """
 
     def lower(date):
         d = {b'mb': b"1", b'd': b"1"}
         return parsedate(date, extendeddateformats, d)[0]
 
     def upper(date):
         d = {b'mb': b"12", b'HI': b"23", b'M': b"59", b'S': b"59"}
         for days in (b"31", b"30", b"29"):
             try:
                 d[b"d"] = days
                 return parsedate(date, extendeddateformats, d)[0]
             except error.ParseError:
                 pass
         d[b"d"] = b"28"
         return parsedate(date, extendeddateformats, d)[0]
 
     date = date.strip()
 
     if not date:
         raise error.Abort(_(b"dates cannot consist entirely of whitespace"))
     elif date[0:1] == b"<":
         if not date[1:]:
             raise error.Abort(_(b"invalid day spec, use '<DATE'"))
         when = upper(date[1:])
         return lambda x: x <= when
     elif date[0:1] == b">":
         if not date[1:]:
             raise error.Abort(_(b"invalid day spec, use '>DATE'"))
         when = lower(date[1:])
         return lambda x: x >= when
     elif date[0:1] == b"-":
         try:
             days = int(date[1:])
         except ValueError:
             raise error.Abort(_(b"invalid day spec: %s") % date[1:])
         if days < 0:
             raise error.Abort(
                 _(b"%s must be nonnegative (see 'hg help dates')") % date[1:]
             )
         when = makedate()[0] - days * 3600 * 24
         return lambda x: x >= when
     elif b" to " in date:
         a, b = date.split(b" to ")
         start, stop = lower(a), upper(b)
         return lambda x: x >= start and x <= stop
     else:
         start, stop = lower(date), upper(date)
         return lambda x: x >= start and x <= stop