2 files changed, 12 insertions, 11 deletions
diff --git a/libjava/java/util/Calendar.java b/libjava/java/util/Calendar.java
index 05d48c2..6e9eda9 100644
--- a/libjava/java/util/Calendar.java
+++ b/libjava/java/util/Calendar.java
@@ -651,6 +651,10 @@ public abstract class Calendar implements Serializable, Cloneable
 	isSet[HOUR_OF_DAY] = false;
 	break;
       }
+
+    // May have crossed over a DST boundary.
+    if (field != DST_OFFSET && field != ZONE_OFFSET)
+      isSet[DST_OFFSET] = false;
   }
 
   /**
@@ -671,6 +675,8 @@ public abstract class Calendar implements Serializable, Cloneable
     isSet[WEEK_OF_MONTH] = false;
     isSet[DAY_OF_WEEK] = false;
     isSet[DAY_OF_WEEK_IN_MONTH] = false;
+
+    isSet[DST_OFFSET] = false;  // May have crossed a DST boundary.
   }
 
   /**
diff --git a/libjava/java/util/GregorianCalendar.java b/libjava/java/util/GregorianCalendar.java
index fcef6bb..2504f60 100644
--- a/libjava/java/util/GregorianCalendar.java
+++ b/libjava/java/util/GregorianCalendar.java
@@ -540,7 +540,7 @@ public class GregorianCalendar extends Calendar
     fields[DAY_OF_WEEK] = weekday;
 
     // get a first approximation of the year.  This may be one 
-    // year to big.
+    // year too big.
     int year = 1970 + (gregorian
 		       ? ((day - 100) * 400) / (365 * 400 + 100 - 4 + 1)
 		       : ((day - 100) * 4) / (365 * 4 + 1));
@@ -709,6 +709,10 @@ public class GregorianCalendar extends Calendar
    * it does what you expect: Jan, 25 + 10 Days is Feb, 4.
    * @param field the time field. One of the time field constants.
    * @param amount the amount of time.
+   * @exception IllegalArgumentException if <code>field</code> is 
+   *   <code>ZONE_OFFSET</code>, <code>DST_OFFSET</code>, or invalid; or
+   *   if <code>amount</code> contains an out-of-range value and the calendar
+   *   is not in lenient mode.
    */
   public void add(int field, int amount)
   {
@@ -785,18 +789,9 @@ public class GregorianCalendar extends Calendar
 	areFieldsSet = false;
 	break;
       case ZONE_OFFSET:
-	complete();
-	fields[ZONE_OFFSET] += amount;
-	time -= amount;
-	break;
       case DST_OFFSET:
-	complete();
-	fields[DST_OFFSET] += amount;
-	isTimeSet = false;
-	break;
       default:
-	throw new IllegalArgumentException
-	  ("Unknown Calendar field: " + field);
+	throw new IllegalArgumentException("Invalid or unknown field");
       }
   }