From 4b6153285040591d626cfd284d25bc25ca598338 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?K=C5=8Dan?= <koan.bot@atoomic.org>
Date: Wed, 6 May 2026 05:29:54 -0600
Subject: [PATCH] fix: align Date::Language::str2time year handling with
 Date::Parse
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Date::Language::str2time was missing two pieces of year normalization
that Date::Parse::str2time applies:

1. Century restoration — when strptime returns a $century value (from
   4-digit year input), the year must be restored via $year += 1900.
   Without this, Language.pm relied on Time::Local treating small
   values as years-since-1900, which works but is fragile.

2. Two-digit year POSIX normalization — Date::Parse uses a fixed
   threshold (69-99 → 1900s, 00-68 → 2000s) matching POSIX strptime
   conventions. Language.pm delegated this to Time::Local's sliding
   window, which on Time::Local >= 1.28 centers on the current year,
   producing different results for years 69-76 (e.g., "1 Jun 69"
   resolves to 2069 via Language but 1969 via Parse).

Also adds explicit fractional-second handling ($frac separation and
re-addition) to match Date::Parse::str2time's approach, instead of
relying on Time::Local accepting float seconds.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 lib/Date/Language.pm | 15 ++++++++++--
 t/lang-str2time.t    | 56 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/lib/Date/Language.pm b/lib/Date/Language.pm
index 17570f4..4af31b6 100644
--- a/lib/Date/Language.pm
+++ b/lib/Date/Language.pm
@@ -79,13 +79,16 @@ sub str2time
  return undef
     unless @t;
 
- my($ss,$mm,$hh,$day,$month,$year,$zone) = @t;
+ my($ss,$mm,$hh,$day,$month,$year,$zone,$century) = @t;
  my @lt  = localtime(time);
 
  $hh    ||= 0;
  $mm    ||= 0;
  $ss    ||= 0;
 
+ my $frac = $ss - int($ss);
+ $ss = int $ss;
+
  $month = $lt[4]
     unless(defined $month);
 
@@ -98,6 +101,14 @@ sub str2time
    $year = $is_future ? ($lt[5] - 1) : $lt[5];
  }
 
+ # Restore 4-digit year when century was present in the input
+ $year += 1900 if defined $century;
+
+ # Normalize two-digit years using POSIX convention (match Date::Parse behavior).
+ # Without this, Time::Local's own sliding window produces different results than
+ # Date::Parse::str2time for the same input string.
+ $year += ($year >= 69 ? 1900 : 2000) if $year < 100;
+
  return undef
     unless($month <= 11 && $day >= 1 && $day <= 31
         && $hh <= 23 && $mm <= 59 && $ss <= 59);
@@ -132,7 +143,7 @@ sub str2time
    return undef if $result < 0 && $year >= 1971;
  }
 
- return $result;
+ return $result + $frac;
 }
 
 1;
diff --git a/t/lang-str2time.t b/t/lang-str2time.t
index 658ed48..d7cc7d3 100644
--- a/t/lang-str2time.t
+++ b/t/lang-str2time.t
@@ -105,4 +105,60 @@ my $lang = Date::Language->new('English');
     is($parsed, $t, "German round-trip ctime/str2time");
 }
 
+# --- Two-digit year normalization: must match Date::Parse ---
+# Without explicit normalization, Date::Language relies on Time::Local's
+# sliding window which diverges from Date::Parse's fixed POSIX threshold.
+
+{
+    for my $y (69, 70, 75, 95, 99) {
+        my $date = "1 Jun $y GMT";
+        my $dp = str2time($date);
+        my $dl = $lang->str2time($date);
+        ok(defined $dp, "Date::Parse parses '1 Jun $y GMT'");
+        ok(defined $dl, "Date::Language parses '1 Jun $y GMT'");
+        if (defined $dp && defined $dl) {
+            my $dp_year = (gmtime($dp))[5] + 1900;
+            my $dl_year = (gmtime($dl))[5] + 1900;
+            is($dl_year, $dp_year,
+                "two-digit year $y: Language ($dl_year) matches Parse ($dp_year)");
+        }
+    }
+
+    # Also test years in the 2000s range
+    for my $y (0, 1, 26, 50, 68) {
+        my $date = "15 Mar $y GMT";
+        my $dp = str2time($date);
+        my $dl = $lang->str2time($date);
+        ok(defined $dp, "Date::Parse parses '15 Mar $y GMT'");
+        ok(defined $dl, "Date::Language parses '15 Mar $y GMT'");
+        if (defined $dp && defined $dl) {
+            my $dp_year = (gmtime($dp))[5] + 1900;
+            my $dl_year = (gmtime($dl))[5] + 1900;
+            is($dl_year, $dp_year,
+                "two-digit year $y: Language ($dl_year) matches Parse ($dp_year)");
+        }
+    }
+}
+
+# --- Four-digit year with century: must survive round-trip ---
+
+{
+    my $date = "15 Mar 2024 10:30:00 GMT";
+    my $dp = str2time($date);
+    my $dl = $lang->str2time($date);
+    ok(defined $dp && defined $dl, "4-digit year parses in both");
+    is($dl, $dp, "4-digit year: Language matches Parse exactly");
+}
+
+# --- Fractional seconds preserved ---
+
+{
+    my $date = "2024-01-15T12:34:56.789 GMT";
+    my $result = $lang->str2time($date);
+    ok(defined $result, "fractional seconds date parses");
+    my $frac = $result - int($result);
+    ok($frac > 0.78 && $frac < 0.80,
+        "fractional seconds preserved (got $frac, expected ~0.789)");
+}
+
 done_testing;