Panama unresolved error when instantiating wayland struct...

Fri Feb 15 01:06:09 UTC 2019

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
>>>>>> 