FastThrow breaks Throwable.addSuppressed ?

[Roger Riggs]

Created an issue to facilitate tracking: 
https://bugs.openjdk.org/browse/JDK-8287921


On 5/31/22 6:59 PM, Eugene Yakavets wrote:
> Throwable#addSuppressed is used for combining exceptions when two
> independent exceptions can be thrown from the same code block. Typical case
> is try-with-resources where one exception is from try block, and another
> from closing resource.
>
> #addSuppressed internally verifies that suppressed exception and current
> exception are not the same. That is a reasonable condition to check, but it
> doesn't seem to work well with fast throw optimization when exceptions are
> being replaced with the same class instance, and that condition starts to
> fail.
>
> Consider the example below: it finishes successfully with
> -XX:-OmitStackTraceInFastThrow flag, and fails with
> IllegalArgumentException "Self-suppression not permitted" if optimization
> is enabled.
>
> public class Test {
>      static class SomeCloseable implements AutoCloseable {
>          @Override
>          public void close() {
>              throwsNPE();
>          }
>      }
>
>      static void throwsNPE() {
>          ((Object) null).getClass();
>      }
>
>      //run with and without -XX:-OmitStackTraceInFastThrow
>      public static void main(String[] args) {
>          for (int i = 0; i < 100_000; i++) {
>              try (SomeCloseable c = new SomeCloseable()) {
>                  throwsNPE();
>              } catch (NullPointerException expectedException) {
>                  assert expectedException.getSuppressed().length == 1;
>              }
>          }
>      }
> }
>
> Could self match be no-op instead of exception in Throwable#addSuppressed?
>
> Thanks,