[External] : Re: jextract wayland-client

[Thiago Milczarek Sayão]

Humm,

It an inline function:

static inline struct wl_registry *
wl_display_get_registry(struct wl_display *wl_display)
{
        struct wl_proxy *registry;

        registry = wl_proxy_marshal_flags((struct wl_proxy *) wl_display,
                         WL_DISPLAY_GET_REGISTRY,
&wl_registry_interface, wl_proxy_get_version((struct wl_proxy *)
wl_display), 0, NULL);

        return (struct wl_registry *) registry;
}


Em dom., 21 de abr. de 2024 às 20:25, Jorn Vernee <jorn.vernee at oracle.com>
escreveu:

> A pointer type is always supported, so it should not prevent a function
> that uses such a type from being generated.
>
> Are you seeing any warnings about `wl_display_get_registry` being skipped
> because of an unsupported type?
>
> Could you shared the header file declaration of wl_display_get_registry?
>
> Jorn
> On 22/04/2024 00:51, Thiago Milczarek Sayão wrote:
>
> Hello Jorn,
>
> Thanks for replying.
>
> I think it's by design - those fields of wl_registry are private and only
> accessible through wl_registry functions;
>
> The problem is that it does not generate the functions that uses it, for
> example wl_display_get_registry
>
> I did:
>
> jextract --output src/main/java -t org.freedesktop.wayland.client \
>   --header-class-name WlClientProto `pkg-config --cflags-only-I wayland-client` \
>   `pkg-config --libs wayland-client`  \
>   /usr/include/wayland-client-protocol.h
>
>
> The clarified message looks good.
>
> Em dom., 21 de abr. de 2024 às 18:30, Jorn Vernee <jorn.vernee at oracle.com>
> escreveu:
>
>> Hello Thiago,
>>
>> It looks like the library you are using uses opaque types. Or, in other
>> words, a type that is declared but not defined, such as:
>>
>>     struct Foo;
>>
>> These types are not supported by jextract in the sense that the header
>> file does not contain any definition for these types, so jextract also
>> can't generate any code to access the fields of such a struct. This is not
>> a current limitation of jextract, but a limitation imposed by the wayland
>> library.
>>
>> This is known as the 'opaque pointer idiom' [1]. It is a way of
>> encapsulating the internals of a type, while still allowing a client to use
>> it. It looks like the wayland library uses types like these in a lot of
>> places. It doesn't mean that the library is unusable, it just means that
>> the contents of these structs is not exposed by the library (and therefore
>> *cannot* be exposed by jextract). i.e. this is by design. You should
>> still be able to use the library through the generated bindings.
>>
>> I think for clarity we could perhaps change the warning message that
>> jextract prints to something like:
>>
>>     WARNING: Skipping wl_registry (type Declared(wl_registry) is declared
>> but not defined)
>>
>> HTH,
>> Jorn
>>
>> [1]: https://en.wikipedia.org/wiki/Opaque_pointer
>> <https://urldefense.com/v3/__https://en.wikipedia.org/wiki/Opaque_pointer__;!!ACWV5N9M2RV99hQ!J7UcZ_pVCMYJLfWJp9TZNELYAFrerMmP-yIjI1X6pBl6Zfx8gKLGiEb8ESgd_FTELrMqKd0F8pBF_Zs6zquT91c$>
>> On 21/04/2024 18:58, Thiago Milczarek Sayão wrote:
>>
>> Hi,
>>
>> I'm trying to make a java wayland client (currently as a proof of
>> concept).
>>
>> I've attempted to generate the bindings like this:
>>
>> jextract --output src -t org.freedesktop.wayland.client
>> --header-class-name WlClient -lwayland-client  /usr/include/wayland-client.h
>>
>> But the wl_xxx types seem to not be supported as it outputs:
>>
>> WARNING: Skipping wl_registry (type Declared(wl_registry) is not
>> supported)
>>
>> I've probably hit a current limitation. Is it expected to work in the
>> future?
>>
>> Thanks.
>> -- Thiago.
>>
>>
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