GLSL 1.50: "in int" is not legal on OS X?

This chunk of code snippet compiles on Windows but throws an error on OS X (Mountain Lion using main context 3.2).

#version 150 core
in int vinstance_id;
uniform uint object_id[16];
out uint id_map;

void main() {
    id_map = object_id[vinstance_id];
}

      

        
        
        
      

    

Mistake:

ERROR: 0:2: int can't be an in in the fragment shader

      

        
        
        
      

    

I don't think this is correct: the GLSL 1.50 spec in section 4.3.4 talks about fragment shaders:

Fragment inputs can only be signed and unsigned integers and integer vectors, float ...

Is this a driver bug?