From d744bf17b7a0e0158eb813a8605cc0d8635f8959 Mon Sep 17 00:00:00 2001
From: Dave Rolsky <autarch@urth.org>
Date: Sat, 3 May 2014 11:39:47 +0800
Subject: [PATCH] Don't leave the object in a modified state after a failed
 truncate( to => 'week' )
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Petr Pisar: Ported to 1.06.

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 lib/DateTime.pm | 11 ++++++++++-
 t/16truncate.t  | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/lib/DateTime.pm b/lib/DateTime.pm
index 1ff4c2e..a8663b2 100644
--- a/lib/DateTime.pm
+++ b/lib/DateTime.pm
@@ -1985,7 +1985,16 @@ sub set_formatter {
                 $self->add( days => -1 * $day_diff );
             }
 
-            return $self->truncate( to => 'day' );
+            # This can fail if the truncate ends up giving us an invalid local
+            # date time. If that happens we need to reverse the addition we
+            # just did. See https://rt.cpan.org/Ticket/Display.html?id=93347.
+            try {
+                $self->truncate( to => 'day' );
+            }
+            catch {
+                $self->add( days => $day_diff );
+                die $_;
+            };
         }
         else {
             my $truncate;
diff --git a/t/16truncate.t b/t/16truncate.t
index 0058f50..a478760 100644
--- a/t/16truncate.t
+++ b/t/16truncate.t
@@ -5,6 +5,7 @@ use Test::Fatal;
 use Test::More 0.88;
 
 use DateTime;
+use Try::Tiny;
 
 my %vals = (
     year       => 50,
@@ -233,4 +234,41 @@ my %vals = (
     }
 }
 
+{
+    my $dt = DateTime->new(
+        year      => 2010,
+        month     => 3,
+        day       => 25,
+        hour      => 1,
+        minute    => 5,
+        time_zone => 'Asia/Tehran',
+    );
+
+    is(
+        $dt->day_of_week(),
+        4,
+        'day of week is Thursday'
+    );
+
+    my $error;
+    try {
+        $dt->truncate( to => 'week' );
+    }
+    catch {
+        $error = $_;
+    };
+
+    like(
+        $error,
+        qr/Invalid local time for date/,
+        'truncate operation threw an error because of an invalid local datetime'
+    );
+
+    is(
+        $dt->day_of_week(),
+        4,
+        'day of week does not change after failed truncate() call'
+    );
+}
+
 done_testing();
-- 
1.9.0