Don't loop forever if a reminder moves backwards because of a time zone difference.

If we are not making progress, it's because the reminder has expired.

src/trigger.c

@@ -554,6 +554,7 @@ int ComputeTriggerNoAdjustDuration(int today, Trigger *trig, TimeTrig const *tim
         y, m, d, omit,
         result;
 
+    int save_nextstart = 0;
     trig->expired = 0;
     if (save_in_globals) {
         LastTrigValid = 0;
@@ -617,14 +618,24 @@ int ComputeTriggerNoAdjustDuration(int today, Trigger *trig, TimeTrig const *tim
 
         /** FIXME: If a timed reminder moves to yesterday because of a time
             zone adjustment, try again! */
-
         if (trig->tz) {
             TimeTrig copy = *tim;
             int new_result;
             ExitTimezone(trig->tz);
             new_result = AdjustTriggerForTimeZone(trig, result, &copy);
             EnterTimezone(trig->tz);
-            if (new_result + duration_days < today) {
+            if (result + duration_days >= today &&
+                new_result + duration_days < today) {
+                /* If we are not making progress, then give up: It's expired */
+                if (nextstart <= save_nextstart) {
+                    trig->expired = 1;
+                    if (DebugFlag & DB_PRTTRIG) {
+                        fprintf(ErrFp, "%s(%s): %s\n",
+                                GetCurrentFilename(), line_range(LineNoStart, LineNo), GetErr(E_EXPIRED));
+                    }
+                    return -1;
+                }
+                save_nextstart = nextstart;
                 nextstart = start+1;
                 start = nextstart;
                 continue;

tests/test-timezone-support

@@ -161,6 +161,9 @@ debug -t
 
 EOF
 
+TZ=America/Toronto $REMIND -s - 2025-09-01@00:00 <<'EOF' >> $OUT 2>&1
+REM 2025-09-24 AT 09:00 TZ America/Denver MSG Dr. Smith
+EOF
 cmp -s $OUT $CMP
 if [ "$?" = "0" ] ; then
     echo "Remind:   Time zone test PASSED"

tests/tz.cmp

@@ -78,3 +78,4 @@ trig("Mon at 00:00 TZ Australia/Sydney", "Tue at 00:00 TZ America/Toronto", "Wed
 -stdin-(14:21): Trig(tz_adj Australia/Sydney) = Saturday, 6 September, 2025 AT 10:00
 -stdin-(14:21): Trig = Monday, 1 September, 2025 AT 14:42
 2025-09-01
+2025/09/24 * * * 660 11:00am Dr. Smith