Clean up "stopgap" implementation of timestamptz_to_str().

Use correct type for "result", fix bogus strftime argument, don't use
unnecessary static variables, improve comments.

Andres Freund and Tom Lane

contrib/pg_xlogdump/compat.c

@@ -41,25 +41,30 @@ timestamptz_to_time_t(TimestampTz t)
 
 /*
  * Stopgap implementation of timestamptz_to_str that doesn't depend on backend
- * infrastructure.
+ * infrastructure.  This will work for timestamps that are within the range
+ * of the platform time_t type.  (pg_time_t is compatible except for possibly
+ * being wider.)
+ *
+ * XXX the return value points to a static buffer, so beware of using more
+ * than one result value concurrently.
  *
  * XXX: The backend timestamp infrastructure should instead be split out and
- * moved into src/common.
+ * moved into src/common.  That's a large project though.
  */
 const char *
 timestamptz_to_str(TimestampTz dt)
 {
 	static char buf[MAXDATELEN + 1];
-	static char ts[MAXDATELEN + 1];
-	static char zone[MAXDATELEN + 1];
-	pg_time_t	result = timestamptz_to_time_t(dt);
+	char		ts[MAXDATELEN + 1];
+	char		zone[MAXDATELEN + 1];
+	time_t		result = (time_t) timestamptz_to_time_t(dt);
 	struct tm  *ltime = localtime(&result);
 
-	strftime(ts, sizeof(zone), "%Y-%m-%d %H:%M:%S", ltime);
+	strftime(ts, sizeof(ts), "%Y-%m-%d %H:%M:%S", ltime);
 	strftime(zone, sizeof(zone), "%Z", ltime);
 
 #ifdef HAVE_INT64_TIMESTAMP
-	sprintf(buf, "%s.%06d %s", ts, (int)(dt % USECS_PER_SEC), zone);
+	sprintf(buf, "%s.%06d %s", ts, (int) (dt % USECS_PER_SEC), zone);
 #else
 	sprintf(buf, "%s.%.6f %s", ts, fabs(dt - floor(dt)), zone);
 #endif