[Challenge] implementing the ambiguous operator in D

[bearophile]

Denis Koroskin:
> Turn main into an "extern(C) int main()" and it works.

This version:

import std.c.stdio: puts;

version (Windows) {
    alias int[16] jmp_buf;
    extern (C) extern {
        int setjmp(ref jmp_buf env);
        void longjmp(ref jmp_buf env, int value);
    }
}

struct State {
     int save() {
         return setjmp(buf);
     }

     void restore(int status) {
         assert(status != 0);
         longjmp(buf, status);
     }

     private jmp_buf buf;
}

extern(C) int main() {
     State state;
     int result = state.save();
     if (result == 0) {
         // first time here
         puts("state saved");
         state.restore(1);
     } else {
         assert(result == 1);
         puts("state restored");
     }
     return 0;
}


Gives link errors:
test.obj(test) 
 Error 42: Symbol Undefined __d_assertm
test.obj(test) 
 Error 42: Symbol Undefined __d_assert_msg

Bye,
bearophile