Panama unresolved error when instantiating wayland struct...

[Maurizio Cimadamore]

Hi Mark,
thanks for the report - from the looks of it, it seems an issue with 
cross-header layout resolution, which is listed in the 'known issues' in 
the EA page:

"Dynamic layout resolution doesn't work across multiple headers."

I will check in more details tomorrow, and confirm, one way or another.

Quick check: are wl_list and wl_listener defined in the same header 
file? If not that's likely the issue here.

I think Pointer<?> is the correct type - jextract tries to insert as 
more general types as possible when inserting Pointer in argument 
position; if it generated Pointer<Void>, and that was an ordinary 
function call, you could only call it with another Pointer<Void> - if 
the argument type is Pointer<?> you can pass _any_ pointer - e.g. 
Pointer<Byte>, Pointer<Integer> which is kind of close to what you can 
do in C.

Maurizio

On 14/02/2019 22:23, Mark Hammons wrote:
> 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
>