The documentation for Time::Piece in 5.30.x states the following:

Date Parsing
Time::Piece has a built-in strptime() function (from FreeBSD), allowing you incredibly flexible date parsing routines. For example: 
  my $t = Time::Piece->strptime("Sunday 3rd Nov, 1943",
                                "%A %drd %b, %Y");
 
  print $t->strftime("%a, %d %b %Y");

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Outputs: 
  Wed, 03 Nov 1943

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(see, it's even smart enough to fix my obvious date bug) For more information see "man strptime", which should be on all unix systems. Alternatively look here: http://www.unix.com/man-page/FreeBSD/3/strftime/

The link includes the following conversion specifications:

%a is replaced by national representation of the abbreviated weekday name.
%d is replaced by the day of the month as a decimal number (01-31).
%b is replaced by national representation of the abbreviated month name.
%Y is replaced by the year with century as a decimal number.
%T is equivalent to ``%H:%M:%S''.
%H is replaced by the hour (24-hour clock) as a decimal number (00-23).
%M is replaced by the minute as a decimal number (00-59).
%S is replaced by the second as a decimal number (00-60).
%Z is replaced by the time zone name.
%z is replaced by the time zone offset from UTC; a leading plus sign stands for east of UTC, a minus sign for west of UTC, hours and minutes follow with two digits each and no delimiter between them (common form for RFC 822 date headers).

The page for strptime on the same site says, "The strptime() function parses the string in the buffer buf according to the string pointed to by format, and fills in the elements of the structure pointed to by timeptr. The resulting values will be relative to the local time zone. Thus, it can be considered the reverse operation of strftime(3)."

I created the following test code as tp_test.pl: 

#!/usr/bin/perl
# vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4:

use strict;
use warnings;

use Carp;
use Time::Piece;

$SIG{__WARN__} = sub { Carp::cluck @_;   };
$SIG{__DIE__}  = sub { Carp::confess @_; };

$| = 1;

my $t = localtime;

my $pattern = "%a, %d %b %Y %T %Z";

my $str = $t->strftime( $pattern );
print "Time is:\n", $str, "\n";
# Format: Wed, 13 Jan 2021 17:22:23 CST

my $u = Time::Piece->strptime( $str, $pattern, );
print "Time is:\n", $u->strftime( $pattern ), "\n";

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I tested the code on the following three (3) platforms:

When I execute the script above, I get the following on all three platforms (differing only by the path to Piece.pm): 
$ perl ./tp_test.pl
Time is:
Wed, 13 Jan 2021 22:21:49 CST
Error parsing time at /usr/lib64/perl5/Time/Piece.pm line 597.
 at ./tp_test.pl line 11.
        main::__ANON__("Error parsing time at 
          /usr/lib64/perl5/Time/Piece.pm line 597.\x{a}") called 
          at /usr/lib64/perl5/Time/Piece.pm line 597
        Time::Piece::strptime("Time::Piece", 
          "Wed, 13 Jan 2021 22:21:49 CST", "%a, %d %b %Y %T %Z") 
          called at ./tp_test.pl line 23
$

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Expected output: 

$ perl ./tp_test.pl
Time is:
Wed, 13 Jan 2021 22:21:49 CST
Time is:
Wed, 13 Jan 2021 22:21:49 CST
$

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The behavior also appears to occur if I change my $t = localtime; to my $t = gmtime; as well, where the timezone is then 'UTC'. If it were only occurring under Cygwin and Strawberry, my first guess would be MSWin-related, but since I am seeing it on a Linux system as well, I'm not sure where to look for the cause of the issue.

Thoughts?

In reply to Question regarding Time::Piece and timezones by atcroft

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