Inherited mutability

test.rs

struct c_struct;

unsafe fn c_function(a : *mut c_struct)
{

}

struct wrapper
{
	payload : *c_struct
}

fn create() -> wrapper
{
    unsafe
    {
        wrapper{payload : ptr::null()}
    }
}

fn function(a : &mut wrapper)
{
    unsafe
    {
        c_function(a.payload);
    }
}

fn main()
{
    let mut w = ~create();
    function(w);
}

/*
bin.rs:25:19: 25:28 error: mismatched types: expected `*mut c_struct` but found `*c_struct` (values differ in mutability)
bin.rs:25         c_function(a.payload);
                             ^~~~~~~~~
error: aborting due to previous error
*/