Re: [ajdt-dev] Signature-matching bug in inter-method declarations?

["Wes Isberg" <wes@xxxxxxxxxxxxxx>]

Hi Phil, all -

Good find - see also bug 50195:

   "overriding introduced methods with default access fails"
   https://bugs.eclipse.org/bugs/show_bug.cgi?id=50195

where Jim said

  This is a known limitation [...]  Only publically introduced 
  members can be overriden by standard Java code.  A corollary 
  of this is that only publically introduced members are 
  generated with non-mangled names and are effectively visible 
  to pure Java compilers.

  In a future release we could relax this restriction for the 
  case where the target class and the aspect are both in the 
  same package and the target is not an interface.  Personally 
  I prefer the simpler rule that clearly separates public 
  introductions from all others.

which suggests a compiler error is warranted, as is a warning
in programming guide's implementation.xml:

  When declaring methods on target types, only methods declared 
  public are recognizable in the bytecode, so methods must be 
  declared public to be overridden in any subtype or to be called 
  from code in a later compile using the target type as a library.

To find known limitations that might not have been documented,
search AspectJ compiler bugs for the keyword "info".

Wes 


> ------------Original Message------------
> From: Adrian Colyer <adrian_colyer@xxxxxxxxxx>
> To: ajdt-dev@xxxxxxxxxxx
> Date: Fri, Aug-27-2004 1:34 PM
> Subject: Re: [ajdt-dev] Signature-matching bug in inter-method declarations?
>
> On a quick look, I think I understand why this program might be 
> breaking. 
> It's a bug though - you should either get an error message at 
> compilation 
> time or a program that runs, but not a program that fails at runtime. 
> In 
> this case the program should run. Please submit a bug report against 
> AspectJ and the compiler component. Thanks.
> 
> (FWIW, some implementation detail:  when a non-public ITD is made on a 
> target type, the method name in the target type is 'obfuscated' so that 
> 
> only the designated set of callers can effectively call it (this is 
> also 
> backed up with type checking). For a public ITD this is not necessary. 
> I 
> suspect the bug is to do with having one 'obfuscated' name and one 
> plain 
> name, *both* introduced by ITDs, and not realising before it is too 
> late 
> that a virtual dispatch to one should call the other - ie. that they 
> have 
> the same signature). 
> 
> -- Adrian
> Adrian_Colyer@xxxxxxxxxx
> 
> 
> 
> Philip Quitslund <philipq@xxxxxxxxxxx> 
> Sent by: ajdt-dev-admin@xxxxxxxxxxx
> 27/08/2004 18:50
> Please respond to
> ajdt-dev@xxxxxxxxxxx
> 
> 
> To
> ajdt-dev@xxxxxxxxxxx
> cc
> 
> Subject
> [ajdt-dev] Signature-matching bug in inter-method declarations?
> 
> 
> 
> 
> 
> 
> Hey All!
> 
> Running the test program below, I get the following error:
> 
> java.lang.AbstractMethodError: 
> trouble.Trouble$A.ajc$interMethodDispatch2$trouble$getName()Ljava/lang/String;
>                  at 
> trouble.Trouble$Bang.ajc$interMethodDispatch1$trouble_Trouble$Bang$trouble_Trouble$A$getName(Trouble.java)
>                  at 
> trouble.Trouble$Bang.ajc$interMethod$trouble_Trouble$Bang$trouble_Trouble$A$toString(Trouble.java:40)
>                  at trouble.Trouble$A.toString(Trouble.java)
>                  at java.lang.String.valueOf(String.java:2131)
>                  at java.io.PrintStream.print(PrintStream.java:462)
>                  at java.io.PrintStream.println(PrintStream.java:599)
>                  at trouble.Trouble.main(Trouble.java:34)
> Exception in thread "main"
> 
> 
> public class Trouble {
> 
>      static abstract class A {}
>      static class B extends A {}
> 
>      public static void main(String[] args) {
>          System.out.println(new B());
>      }
> 
>      static aspect Bang {
>          abstract String A.getName();
>          public String B.getName() { return "B"; }
>          public String A.toString() { return getName(); }
>      }
> }
> 
> 
> The crux is in my declaration of A.getName() as package access and 
> B.getName() as public.  If they both have identical access modifiers 
> the 
> program runs fine...
> 
> Version Info:
> 
> Version: 1.1.12
> Build id: 20040813151120
> AspectJ version: 1.2.0
> 
> and:
> 
> j2sdk1.4.2_02
> 
> 
> Am I missing something obvious or should I submit it to bugzilla?
> 
> 
> Thanks,
> 
> -phil
> 
> 
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