Panama unresolved error when instantiating wayland struct...

Sundararajan Athijegannathan sundararajan.athijegannathan at oracle.com
Fri Feb 15 02:29:18 UTC 2019 

Not tested/reviewed yet. But I see that your IDE has converted specific 
imports to import * again :)

-Sundar

On 15/02/19, 6:36 AM, Jorn Vernee wrote:
> FWIW, I've previously used the following fix to work around a similar 
> issue (also involving a linked lists).
>
> (Rough) Webrev: 
> http://cr.openjdk.java.net/~jvernee/panama/webrevs/8219042/webrev.00/
>
> Cheers,
> Jorn
>
> Maurizio Cimadamore schreef op 2019-02-15 01:14:
>> Here's the bug reference I've created:
>>
>> https://bugs.openjdk.java.net/browse/JDK-8219042
>>
>> unfortunately, I tried allocating the structs in different order and
>> the problem cannot be resolved at the client side.
>>
>> Maurizio
>>
>> On 15/02/2019 00:06, Mark Hammons wrote:
>>> I previously allocated a wl_list in my code. I'm still new to the 
>>> foreign interfaces, so I'm not aware if there's a way to allocate 
>>> the wl_listener using a pre-allocated wl_list.
>>>
>>> Mark
>>>
>>> On 2/15/19 12:49 AM, Maurizio Cimadamore wrote:
>>>>
>>>> On 14/02/2019 23:38, Mark Hammons wrote:
>>>>> Hi Maurizio,
>>>>>
>>>>> No, wl_list is defined in wayland_utils.h while wl_listener is in 
>>>>> wayland_server_core.h. I am currently looking through the issues 
>>>>> on the openjdk tracker and seeing if there's a mitigation for this.
>>>>
>>>> Right - you beat me to this:
>>>>
>>>> https://people.freedesktop.org/~whot/wayland-doxygen/wayland/Server/structwl__listener.html 
>>>> and
>>>>
>>>> https://people.freedesktop.org/~whot/wayland-doxygen/wayland/Server/structwl__list.html 
>>>> Unfortunately this issue is not easy to workaround. I'll make sure 
>>>> to create a JBS entry for it (we do have one, but it's probably not 
>>>> visible outside).
>>>>
>>>> I'll also try to play with this a bit to see what can be done - 
>>>> with this issue sometimes it helps to allocate the inner struct 
>>>> first (e.g. wl_list), and then the one that depends on it (e.g. 
>>>> wl_listener).
>>>>
>>>> Maurizio
>>>>
>>>>>
>>>>> ~Mark
>>>>>
>>>>> On 2/15/19 12:30 AM, Maurizio Cimadamore wrote:
>>>>>> 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
>>>>>>>

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