Possible bug with defender method that calls itself

[Maurizio Cimadamore]

On 16/12/11 11:56, Per Rovegård wrote:
> On Fri, Dec 16, 2011 at 12:15 PM, Maurizio Cimadamore
> <maurizio.cimadamore at oracle.com>  wrote:
>> The program should give a StackTraceException - however as pointed out by
>> Robert and Brian, VM support for extension methods is not in place yet -
>> there are cases (like the one you posted yesterday) in which things seem to
>> 'just' work, but that's mostly by accident. In the most general case you
>> will get AbstractMethodErrror if you don't run the extensin method static
>> weaver on your classes.
> You're right - when I run the weaver on the classes I get a
> StackOverflowError as expected!
>
> How is it that some cases work "by accident" as you say? When I tried
> to build the lambda source *without* defender-prototype in place the
> build script stopped with an error. That's why I assumed that
> defender-prototype weaving had been incorporated in some way.
The weaver is only executed on JDK classes (i.e. Collection).
For custom-defined classes the weaver needs to be run manually.

Maurizio

>
> -- Per
>
>
>> On 16/12/11 08:24, Per Rovegård wrote:
>>> Hi,
>>>
>>> While testing defender methods, I wrote the following small program:
>>>
>>> public class TestDefender2 {
>>>          public static interface A {
>>>                  String sayHi() default { return sayHi(); };
>>>          }
>>>
>>>          public static class AImpl implements A { }
>>>
>>>          public static void main(String[] args) throws Exception {
>>>                  System.out.println(new AImpl().sayHi());
>>>          }
>>> }
>>>
>>> How should the program behave? I would expect to get one of the following:
>>> a) A compilation error, saying that I try to call an abstract method, or
>>> b) A StackOverflowError at runtime resulting from infinite recursion.
>>>
>>> But it compiles successfully and when run it gives:
>>>
>>> $ ../lambda/build/linux-amd64/j2sdk-image/bin/java TestDefender2
>>> Exception in thread "main" java.lang.AbstractMethodError:
>>> TestDefender2$AImpl.sayHi()Ljava/lang/String;
>>>          at TestDefender2$A.sayHi(TestDefender2.java:3)
>>>          at TestDefender2.main(TestDefender2.java:9)
>>>
>>> Is this a bug?
>>>
>>> Br,
>>> Per
>>>