[foreign-jextract] Duplicated interface declarations when using typedefs for function pointers

[Maurizio Cimadamore]

Filed this:

https://bugs.openjdk.java.net/browse/JDK-8260602

Thanks for the report!

Maurizio


On Thu, 2021-01-28 at 17:57 +0000, Maurizio Cimadamore wrote:
> This seems odd. But I guess I can see why jextract ends up doing
> that.
> 
> I think what jextract *should* do is to reuse the interface for
> `callback_t` whenever possible (which should be declared at the
> toplevel).
> 
> In other words, it seems like jextract is re-generating a new
> interface
> every time it encounters a reference to a function pointer typedef,
> which seems a bug.
> 
> Maurizio
> 
> 
> 
> On Thu, 2021-01-28 at 18:48 +0100, Filip Krakowski wrote:
> > Hi,
> > 
> > I just noticed that jextract generates duplicate code (interfaces)
> > for 
> > function pointers within each struct instead at the top-level.
> > Each interface's name seems to have a suffix based on the
> > occurrence
> > of 
> > the declaration in the source file.
> > 
> >     typedef void (*callback_t)(void *arg);
> > 
> >     typedef struct first_handler {
> >          callback_t cb;
> >     } first_handler_t;
> > 
> >     typedef struct second_handler {
> >          callback_t cb;
> >     } second_handler_t;
> > 
> > This code generates the following java source code.
> > 
> >     @C("struct first_handler")public static class first_handler {
> >     ...
> >          public static interface cb {
> > 
> >                  void apply(jdk.incubator.foreign.MemoryAddress
> > x0);
> > 
> >                  public static  @C("callback_t") MemorySegment
> >     allocate(cb fi) {
> >                      return RuntimeHelper.upcallStub(cb.class, fi,
> >     ucx_h_constants_0.cb$FUNC(),
> >     "(Ljdk/incubator/foreign/MemoryAddress;)V");
> >                  }
> > 
> >                  public static  @C("callback_t") MemorySegment
> >     allocate(cb fi, NativeScope scope) {
> >                      return allocate(fi).handoff(scope);
> >                  }
> >              }
> >     ...
> >     }
> > 
> >     @C("struct second_handler")public static class second_handler {
> >     ...
> >          public static interface cb$0 {
> > 
> >                  void apply(jdk.incubator.foreign.MemoryAddress
> > x0);
> > 
> >                  public static  @C("callback_t") MemorySegment
> >     allocate(cb$0 fi) {
> >                      return RuntimeHelper.upcallStub(cb$0.class,
> > fi,
> >     ucx_h_constants_0.cb$0$FUNC(),
> >     "(Ljdk/incubator/foreign/MemoryAddress;)V");
> >                  }
> > 
> >                  public static  @C("callback_t") MemorySegment
> >     allocate(cb$0 fi, NativeScope scope) {
> >                      return allocate(fi).handoff(scope);
> >                  }
> >              }
> >     ...
> >     }
> > 
> >  From my point of view both interfaces are identical. Is there a
> > reason 
> > for placing them inside the struct class?
> > 
> > 
> > Best regards
> > Filip
> > 
> >