Panama unresolved error when instantiating wayland struct...

[Mark Hammons]

Hi all,

I decided to try to take the dive on project panama, starting with 
making a binding to linux's wayland server. I used the following 
command: ~/bin/jdk-13/bin/jextract 
/usr/include/wayland/wayland-server-core.h 
/usr/include/wayland/wayland-server.h 
/usr/include/wayland/wayland-util.h 
/usr/include/wayland/wayland-version.h 
/usr/include/wayland/wayland-server-protocol.h -I /usr/include/wayland 
-L /usr/lib64/ --record-library-path -l wayland-server -t wayland -o 
wayland_server.jar


When I try to allocate a wl_listener struct, I get the following error:

[error] Exception in thread "main" 
java.lang.UnsupportedOperationException: bitsSize on Unresolved
[error]     at 
java.base/java.foreign.layout.Unresolved.bitsSize(Unresolved.java:76)
[error]     at 
java.base/java.util.stream.ReferencePipeline$5$1.accept(ReferencePipeline.java:229)
[error]     at 
java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948)
[error]     at 
java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
[error]     at 
java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
[error]     at 
java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
[error]     at 
java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
[error]     at 
java.base/java.util.stream.LongPipeline.reduce(LongPipeline.java:474)
[error]     at 
java.base/java.util.stream.LongPipeline.sum(LongPipeline.java:432)
[error]     at java.base/java.foreign.layout.Group.bitsSize(Group.java:119)
[error]     at 
java.base/java.foreign.memory.LayoutType.bytesSize(LayoutType.java:49)
[error]     at 
java.base/jdk.internal.foreign.ScopeImpl.allocateInternal(ScopeImpl.java:66)
[error]     at 
java.base/jdk.internal.foreign.ScopeImpl.allocate(ScopeImpl.java:92)
[error]     at 
java.base/jdk.internal.foreign.ScopeImpl.allocateStruct(ScopeImpl.java:98)
[error]     at TestApp$.delayedEndpoint$TestApp$1(TestApp.scala:22)
[error]     at TestApp$delayedInit$body.apply(TestApp.scala:13)
[error]     at scala.Function0.apply$mcV$sp(Function0.scala:39)
[error]     at scala.Function0.apply$mcV$sp$(Function0.scala:39)
[error]     at 
scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17)
[error]     at scala.App.$anonfun$main$1$adapted(App.scala:80)
[error]     at scala.collection.immutable.List.foreach(List.scala:392)
[error]     at scala.App.main(App.scala:80)
[error]     at scala.App.main$(App.scala:78)
[error]     at TestApp$.main(TestApp.scala:13)
[error]     at TestApp.main(TestApp.scala)

Looking at other bugs involving this kind of error message, it appears 
that unresolved is a type for when there's not enough layout 
information? In any case, here's the struct in question:

struct wl_listener {
         struct wl_list link;
         wl_notify_func_t notify;
};

and the definition of the elements:

typedef void (*wl_notify_func_t)(struct wl_listener *listener, void *data);

struct wl_list {
         /** Previous list element */
         struct wl_list *prev;
         /** Next list element */
         struct wl_list *next;
};

I'm fairly certain the issue lies with the function pointer notify. When 
I looked at the decompiled source, wl_notify_func_t is defined as:

     @FunctionalInterface
     @NativeCallback("(u64:${wl_listener}u64:v)v")
     public interface FI5 {
         void fn(Pointer<wayland_server_core.wl_listener> var1, 
Pointer<?> var2);
     }


which seems suspicious to me. var2 should be a Pointer<Void> I would 
think. It's a type I see elsewhere in the source for this file, so it 
seems suspect that var2 is a Pointer<?>.


Is this a bug? Am I just using jextract wrong?

Thanks for your help,

Mark Hammons