Cannot compile projects with emsdk 4.0.9

[Honya2000]

Hello,

Today i updated emsdk to 4.0.9 and suddenly all my projects aren't compilable anymore.
There ar several issues...
But currently i'm stuck with callbacks solution:
In emscripten binding i pass emscripten::val parameter as lambda callback:

    .function("processInputBuf", &NativeEngineAI::processInputBuf, allow_raw_pointers())

The function is declared like this
  bool processInputBuf(uintptr_t buf, int width, int height, uint64_t timeStamp,
#ifdef __EMSCRIPTEN__
    emscripten::val lambda
#else
    CallbackFrame lambda
#endif
  );

And callback is invocked this way:

#ifdef __EMSCRIPTEN__
  // Convert GpuBuffer to ImageFrame.
  MP_RETURN_IF_ERROR(_gpu_helper.RunInGlContext([&packet, buf, this]() -> absl::Status 
    {
      auto& gpu_frame = packet.Get<mediapipe::GpuBuffer>();
      buf->maskTexture = this->_gpu_helper.CreateSourceTexture(gpu_frame);

      buf->m_callBack(buf);
      delete buf;

      return absl::OkStatus();
    }));
#endif

This code was working 3 years. Currently it throws error on line:
buf->m_callBack(buf);

C:\Projects\emsdk\upstream\emscripten\cache\sysroot/include\emscripten/wire.h:124:19: error: static assertion failed due to requirement '!std::is_pointer<SFrameBuf *>::value': Implicitly binding raw pointers is illegal.  Specify allow_raw_pointer<arg<?>>
  124 |     static_assert(!std::is_pointer<T*>::value, "Implicitly binding raw pointers is illegal.  Specify allow_raw_pointer<arg<?>>");
      |                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\Projects\emsdk\upstream\emscripten\cache\sysroot/include\emscripten/wire.h:147:26: note: in instantiation of template class 'emscripten::internal::TypeID<SFrameBuf *>' requested here
...
/engine-tmrw/apps/Session.cpp:226:22: note: in instantiation of function template specialization 'emscripten::val::operator()<SFrameBuf *const &, emscripten::allow_raw_pointers>' requested here
  226 |       buf->m_callBack(buf);

I tried to change the line this way:
buf->m_callBack(buf, allow_raw_pointers());

But this didn't help. It still throws error on the same line.

So how should i handle emsscripten callbacks now?

P.S SFrameBuf structure which i pass to callback is emscripten bound type.

[sbc100]

I'm not sure what changed here. @brendandahl might know.

You could also follow the bisect instruction to narrow down which change caused this issue: https://emscripten.org/docs/contributing/developers_guide.html#bisecting

[brendandahl]

This is most likely from #24175, where I started more consistently enforcing pointer policies with val. I think it was somewhat an accident that pointers were allowed by default for operator() and call. I'll look into adding policies for them so they are allowed.

[Honya2000]

So as far as i understood - there is no way to adopt my code for emsdk 4.0.9 ?
The only way is to rollback to 4.0.8 ?

[brendandahl]

Yes, I'll hopefully have a fix this week or next and get it into the next release.

[brendandahl]

I thought of a workaround, if you do really want to use 4.0.9. You could wrap the pointer in a val to allow a raw pointers e.g.

buf->m_callBack(val(buf, allow_raw_pointers()));

[Honya2000]

Hello,

I just tried to compile my projects with latest emsdk, and still have issues...
Callback can be fixed with the way you suggested but there are many other places, where it shows some errors which wasn't triggered before:

For example here in class function embind declaration:
.function("getMaterials", &emRoom::getMaterials, allow_raw_pointers())
it throws error:
C:\Projects\emsdk\upstream\emscripten\cache\sysroot/include\emscripten/wire.h:124:19: error: static assertion failed due to requirement '!std::is_pointer<Tmrw::Engine::CSourceMaterial *>::value': Implicitly binding raw pointers is illegal. Specify allow_raw_pointer<arg> 124 | static_assert(!std::is_pointer::value, "Implicitly binding raw pointers is illegal. Specify allow_raw_pointer>");
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\Projects\emsdk\upstream\emscripten\cache\sysroot/include\emscripten/wire.h:147:26: note: in instantiation of template class 'emscripten::internal::TypeID<Tmrw::Engine::CSourceMaterial *>' requested here
147 | struct TypeID : TypeID {

c++ function getMaterials declared like this:
std::vector<CSourceMaterial*> getMaterials();
I tried to change embind declaration this way:
.function("getMaterials", &emRoom::getMaterials, allow_raw_pointer<CSourceMaterial>())
But this didn't change anything, the same exactly error.
I tried to google the problem, and didn't find anything useful, no any examples. There are many questions about allow_raw_pointer semantics which kept unanswered.

[Honya2000]

I tried many ways, but nothing worked for me:

For example this throwing the same error:

     .function("getMaterials", EMBIND_LAMBDA(std::vector<CSourceMaterial*>, (emRoom* self),
            {
                std::vector<CSourceMaterial*> mats = self->getMaterials();
                return val(mats, allow_raw_pointer<CSourceMaterial>());
            }))