Exception at address when defining member function in generic class with another generic parameter

[Cazadorro]

When I run this:

// test_shader.slang
namespace ns{

    public interface IBinaryElementWiseFunction<T>{
       public static T call(const in T lhs, const in T rhs);
    }
    public struct AddOp<T : IArithmetic> : IBinaryElementWiseFunction<T>{
      public static  T call(const in T lhs, const in T rhs){
            return lhs + rhs; 
        }
    }
     public struct BinaryElementWiseInputData<T : IArithmetic>{
        public Ptr<T> lhs; 
        public Ptr<T> rhs; 
        public Ptr<T> out; 
        public uint64_t size; 

    
        public void test<U : IBinaryElementWiseFunction<T>>(U  x){
            out[0] = x.call(lhs[0] ,rhs[0]);
        }
    }
}

[[vk::push_constant]] ns::BinaryElementWiseInputData<uint32_t> array_info; 

[shader("compute")]
[numthreads(1024,1,1)]
void add_main(uint3 threadId: SV_DispatchThreadID) {
     ns::BinaryElementWiseInputData<uint32_t> temp = array_info; 
    if (threadId.x < array_info.size) {
        let index = threadId.x; 

        temp.test(ns::AddOp<uint32_t>());
    }    
}

My program straight up crashes in version v2024.1.10. I just see:

 slangModule = session->loadModule("test_shader", diagnosticBlob.writeRef());

and a crash in the binary:

callq  *0x1fb6b4(%rip)          
nopl   (%rax,%rax)   

and

Exception: Exception 0xe06d7363 encountered at address 0x7ffcf33753ac

If there's supposed to be debug symbols with this, I'm not seeing them in the packaged release, I'm running CMake in its debug configuration.

[csyonghe]

The problem here is that there is a mismatch in the implicit generic parameter list of the interface and the implementation.

The interface IBinaryElementWiseFunction<T>::call is in the form of:

T call<T>(...)

while AddOp<T>::call is in the form of

T call<T:IArithmetic>(...)

where there is an additional type constraint on T, so the signatures doesn't match exactly.

Our semantic checking logic has a place where we are synthesizing witness requirements from compatible existing methods, but that logic is missing a case in detecting the mismatch of generic constraints.

[csyonghe]

@Cazadorro A workaround while we work on the fix is to add the constraint to IBinaryElementWiseFunction:

public interface IBinaryElementWiseFunction<T:IArithmetic>{
       public static T call(const in T lhs, const in T rhs);
    }

[csyonghe]

I have a fix in review. Nested generics like this is still under tested, so please use with caution. Let us know if you run into any further issues and we will make sure to either come up with a fix, or implement checking/validation rules to restrict the use of generics that are beyond the capability of the type system.