Can we disallow appending integer to string?

[Nick Treleaven via Digitalmars-d-learn]

This bug is fixed as the code no longer segfaults but throws 
instead:
https://issues.dlang.org/show_bug.cgi?id=5995
void main(){
        string ret;
        int i = -1;
        ret ~= i;
}

Why is it legal to append an integer?