Why D const is annoying

[Mafi]

Am 11.12.2011 19:00, schrieb Walter Bright:
> On 12/11/2011 9:07 AM, Mafi wrote:
>> But what about:
>> void f(ref inout(int)* a, inout(int)* b) { a = b; }
>> This cant work with const because that would violate the const system.
>> I think
>> the rule should be that either the return type must be inout or at
>> least one
>> ref/out parameter.
>> Am I overlooking something?
>
> It should work with const.

But allowing a variable of type abc(int)* where abc is immutable or 
nothing (ie mutable) to be passed to a parameter of the type ref/out 
const(int)* breaks the type system.

void f(ref const(int)* a, const(int)* b) {a = b; }
void main() {
   immutable(int)* a;
   auto b = (new int[](5)).ptr;
   f(a, b);
   //if this compiles I have just assigned a mutable pointer
   //to an immutable one
}

With the above definition using inout, such a call would be disallowed.