This error message had me scratching my head for half an hour. Please fix this situation to report the appropriate error.

This code produces the error:
  Error: inout method db.ui.listadapter.S.f is not callable using a mutable object

struct S
{
	inout(int) f(int x) inout // inout method
	{
		return x;
	}
}

void f(size_t s)
{
	S x;

	// call it with the wrong type (size_t, expects int)
	x.f(s); // very surprising error message

	// call with appropriate type, no problem
	x.f(cast(int)s);
}