Edit report at https://bugs.php.net/bug.php?id=79580&edit=1
ID: 79580
Comment by: rowan dot collins at gmail dot com
Reported by: mcab at acm dot org
Summary: date_create_from_format misses leap year
Status: Verified
Type: Bug
Package: Date/time related
Operating System: Linux
PHP Version: 7.2.30
Block user comment: N
Private report: N
New Comment:
Test and tentative fix here: https://github.com/php/php-src/compare/PHP-7.3...IMSoP:bug-79580
(will actually need a change to timelib, but I'm not sure how to test it there).
This implements the approach in my last comment, but results in a change of behaviour for the
slightly odd case of specifying a day-of-year and then a month within the same time string:
echo DateTimeImmutable::createFromFormat("z m Y", '58 3
2019')->format('z: Y-m-d'), "\n";
# Previously "86: 2019-03-28"
# Now "117: 2019-04-28"
I'm not sure what to do about that, or even what the correct behaviour for that combination
should be.
Previous Comments:
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[2020-05-10 13:45:17] rowan dot collins at gmail dot com
It looks like the problem is that the 'z' specifier works by setting "month=1,
day=X" (in this case, "the 60th of January"), then normalising the date immediately.
But at that point, it doesn't know what year to use for the normalisation, so picks 1970 (which
wasn't a leap year).
https://heap.space/xref/php-src/ext/date/lib/parse_date.c?r=9c608bd1#25213
If you reverse the format, you get the expected result, because the correct year has already been
selected when the "normalise" call happens:
$TZ=timezone_open( "UTC" );
$refdate=date_create_from_format ( "Y z" ,"2020 60" ,$TZ );
echo date_format($refdate,"d/m/Y");
# 01/03/2020
A possible fix would be to delay the call to timelib_do_normalize until after the whole input has
been parsed, including the year specifier.
------------------------------------------------------------------------
[2020-05-10 13:41:20] cmb@php.net
Confirmed: <https://3v4l.org/Drfk6>.
------------------------------------------------------------------------
[2020-05-10 13:22:00] mcab at acm dot org
Description:
------------
date_create_from_format when format is 'z Y' is a day out when day number is after feb28.
Test script:
---------------
$TZ= timezone_open( "UTC" );
$refdate=date_create_from_format ( "z Y" ,"31 2020" ,$TZ );
echo date_format($refdate,"d/m/Y")."<br>";
$refdate=date_create_from_format ( "z Y" ,"60 2020" ,$TZ );
echo date_format($refdate,"d/m/Y")."<br>";
$refdate=date_create_from_format ( "z Y" ,"91 2020" ,$TZ );
echo date_format($refdate,"d/m/Y")."<br>";
$refdate=date_create_from_format ( "z Y" ,"121 2020" ,$TZ );
echo date_format($refdate,"d/m/Y")."<br>";
$refdate=date_create_from_format ( "z Y" ,"130 2020" ,$TZ );
echo date_format($refdate,"d/m/Y")."<br>";
/* Output is
01/02/2020
02/03/2020 <- This has missed the fact that 2020 is a leap year
02/04/2020 <- All future date are wrong
02/05/2020
11/05/2020
*/
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Edit this bug report at https://bugs.php.net/bug.php?id=79580&edit=1