Implicit type conversions with data loss

[ctrl]

I don't want them to be performed at all. How do I disable this 
'feature'?

For example, take a look at this code:
import std.stdio;
void main() {
        int x = -1;
        uint b = x;
        writeln(b);
}

It outputs 4294967295, but I want a compile-time error instead. 
Any suggestions?
(compiler version dmd 2.059)