Code review request for 8012044: Give more information about self-suppression from Throwable.addSuppressed

[Joe Darcy]

On 04/12/2013 11:22 AM, Jason Mehrens wrote:
> The landmines are the retrofitted exception classes as shown here 
> https://netbeans.org/bugzilla/show_bug.cgi?id=150969 and 
> https://issues.jboss.org/browse/JBREM-552. Really, if the ISE or IAE 
> is thrown it is going to suppress 'this' and 'cause'.  It would be 
> nice to see the given 'cause' show up in a log file when tracking down 
> this type of bug.

Okay; fair enough. Updated webrev covering initCause too at

     http://cr.openjdk.java.net/~darcy/8012044.1/

New patch below.

(It is a bit of stretch to have this in initiCause by listed as the 
"cause" of the IllegalStateException; as an alternative, the 
IllegalStateException could have both this and the cause as suppressed 
exceptions.)

Cheers,

-Joe

--- old/src/share/classes/java/lang/Throwable.java    2013-04-12 
12:03:48.000000000 -0700
+++ new/src/share/classes/java/lang/Throwable.java    2013-04-12 
12:03:48.000000000 -0700
@@ -452,10 +452,14 @@
       * @since  1.4
       */
      public synchronized Throwable initCause(Throwable cause) {
-        if (this.cause != this)
-            throw new IllegalStateException("Can't overwrite cause");
+        if (this.cause != this) {
+            IllegalStateException ise =
+                new IllegalStateException("Can't overwrite cause", this);
+            ise.addSuppressed(cause);
+            throw ise;
+        }
          if (cause == this)
-            throw new IllegalArgumentException("Self-causation not 
permitted");
+            throw new IllegalArgumentException("Self-causation not 
permitted", this);
          this.cause = cause;
          return this;
      }
@@ -1039,7 +1043,7 @@
       */
      public final synchronized void addSuppressed(Throwable exception) {
          if (exception == this)
-            throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE);
+            throw new 
IllegalArgumentException(SELF_SUPPRESSION_MESSAGE, exception);

          if (exception == null)
              throw new NullPointerException(NULL_CAUSE_MESSAGE);
--- old/test/java/lang/Throwable/SuppressedExceptions.java 2013-04-12 
12:03:49.000000000 -0700
+++ new/test/java/lang/Throwable/SuppressedExceptions.java 2013-04-12 
12:03:48.000000000 -0700
@@ -26,7 +26,7 @@

  /*
   * @test
- * @bug     6911258 6962571 6963622 6991528 7005628
+ * @bug     6911258 6962571 6963622 6991528 7005628 8012044
   * @summary Basic tests of suppressed exceptions
   * @author  Joseph D. Darcy
   */
@@ -40,6 +40,7 @@
          serializationTest();
          selfReference();
          noModification();
+        initCausePlumbing();
      }

      private static void noSelfSuppression() {
@@ -48,7 +49,9 @@
              throwable.addSuppressed(throwable);
              throw new RuntimeException("IllegalArgumentException for 
self-suppresion not thrown.");
          } catch (IllegalArgumentException iae) {
-            ; // Expected
+            // Expected to be here
+            if (iae.getCause() != throwable)
+                throw new RuntimeException("Bad cause after 
self-suppresion.");
          }
      }

@@ -208,4 +211,29 @@
              super("The medium.", null, enableSuppression, true);
          }
      }
+
+    private static void initCausePlumbing() {
+        Throwable t1 = new Throwable();
+        Throwable t2 = new Throwable("message", t1);
+        Throwable t3 = new Throwable();
+
+        try {
+            t2.initCause(t3);
+            throw new RuntimeException("Shouldn't reach.");
+        } catch (IllegalStateException ise) {
+            if (ise.getCause() != t2)
+                throw new RuntimeException("Unexpected cause in ISE", ise);
+            Throwable[] suppressed = ise.getSuppressed();
+            if (suppressed.length != 1 || suppressed[0] != t3)
+                throw new RuntimeException("Bad suppression in ISE", ise);
+        }
+
+        try {
+            t3.initCause(t3);
+            throw new RuntimeException("Shouldn't reach.");
+        } catch (IllegalArgumentException iae) {
+            if (iae.getCause() != t3)
+                throw new RuntimeException("Unexpected cause in ISE", iae);
+        }
+    }
  }