Embind fails to bind a pointer property with getter & setter #24225

GulgDev · 2025-04-30T19:16:04Z

Please include the following in your bug report:

Version of emscripten/emsdk:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 4.0.6 (1ddaae4d2d6dfbb678ecc193bc988820d1fc4633)
clang version 21.0.0git (https:/github.com/llvm/llvm-project 4775e6d9099467df9363e1a3cd5950cc3d2fde05)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: C:\Users\user\Downloads\emsdk\upstream\bin

Failing command line in full:

C:\Users\user\Desktop\Projects\other\embind-property-repro> emcc main.cpp -lembind
In file included from main.cpp:1:
In file included from C:\Users\user\Downloads\emsdk\upstream\emscripten\cache\sysroot/include\emscripten/bind.h:26:
In file included from C:\Users\user\Downloads\emsdk\upstream\emscripten\cache\sysroot/include\emscripten/val.h:17:
C:\Users\user\Downloads\emsdk\upstream\emscripten\cache\sysroot/include\emscripten/wire.h:118:19: error: static assertion failed due to requirement '!std::is_pointer<Thing *>::value': Implicitly      
      binding raw pointers is illegal. Specify allow_raw_pointer<arg<?>>
  118 |     static_assert(!std::is_pointer<T*>::value, "Implicitly binding raw pointers is illegal.  Specify allow_raw_pointer<arg<?>>");
      |                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\Users\user\Downloads\emsdk\upstream\emscripten\cache\sysroot/include\emscripten/bind.h:1946:13: note: in instantiation of template class 'emscripten::internal::TypeID<Thing *>' requested here      
 1946 |             TypeID<typename GP::ReturnType>::get(),
      |             ^
main.cpp:31:10: note: in instantiation of function template specialization 'emscripten::class_<MyClass>::property<emscripten::internal::DeduceArgumentsTag, Thing *(MyClass::*)() const, void
      (MyClass::*)(Thing *), emscripten::allow_raw_pointers, emscripten::return_value_policy::reference, void>' requested here
   31 |         .property("thing", // error: Implicitly binding raw pointers is illegal.
      |          ^
1 error generated.
emcc: error: 'C:/Users/user/Downloads/emsdk/upstream/bin\clang.exe -target wasm32-unknown-emscripten -fignore-exceptions -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --sysroot=C:\Users\user\Downloads\emsdk\upstream\emscripten\cache\sysroot -DEMSCRIPTEN -Xclang -iwithsysroot/include\fakesdl -Xclang -iwithsysroot/include\compat -c main.cpp -o C:\Users\user\AppData\Local\Temp\emscripten_temp_nw0nf3r9\main_0.o' failed (returned 1)

#include <emscripten/bind.h>

using namespace emscripten;

class Thing {
public:
    int value;

    Thing() : value(0) {}
};

class MyClass {
public:
    Thing *thing;

    Thing* getThing() const {
        return thing;
    }

    void setThing(Thing* thing) {
        this->thing = thing;
    }
};

EMSCRIPTEN_BINDINGS(Example) {
    class_<Thing>("Thing")
        .constructor()
        .property("value", &Thing::value);

    class_<MyClass>("MyClass")
        .property("thing", // error: Implicitly binding raw pointers is illegal.
                  &MyClass::getThing,
                  &MyClass::setThing,
                  allow_raw_pointers(),
                  return_value_policy::reference());
}

Repro: https://github.com/GulgDev/embind-property-repro

The text was updated successfully, but these errors were encountered:

…ion. When using separate getter and setter functions for class properties the setter function did not have policies applied to it. This caused setters with raw pointers to fail. For now, use the supplied return value policy to allow pointers. In the future we should probably add separate polices for arguments, but that will be a much bigger change. Note: I've added a lot more testing for properties and return value polices. This has highlighted a few issues where we seem to be creating extra copies. Fixes: emscripten-core#24225

sbc100 assigned brendandahl Apr 30, 2025

brendandahl linked a pull request May 1, 2025 that will close this issue

[embind] Allow pointers for properties with a getter and setter function. #24239

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Embind fails to bind a pointer property with getter & setter #24225

Embind fails to bind a pointer property with getter & setter #24225

GulgDev commented Apr 30, 2025 •

edited

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Embind fails to bind a pointer property with getter & setter #24225

Embind fails to bind a pointer property with getter & setter #24225

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GulgDev commented Apr 30, 2025 • edited Loading

GulgDev commented Apr 30, 2025 •

edited

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