Panama unresolved error when instantiating wayland struct...

Jorn Vernee jbvernee at xs4all.nl
Fri Feb 15 12:03:17 UTC 2019 

It's not a 100% airtight; it relies on the fact that each element of the 
struct actually has an accessor defined for it. Technically someone 
could just not have accessors for certain a field, and then this fix 
wouldn't work. But, maybe it will help close the gap a little until we 
have a more high-caliber solution.

Jorn

Maurizio Cimadamore schreef op 2019-02-15 02:14:
> Thanks Jorn - clever approach; I'll give this some though to make sure
> it covers all the bases.
> 
> Maurizio
> 
> On 15/02/2019 01:06, 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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