[gecode-users] NaryUnion, infinite loop

[Jean-Noël Monette]

Hello,

Here is a new problem I came across with NaryUnion. As suggested by 
Christian, I created a fresh region for every new NaryUnion, however I 
ran into an infinite loop. Below is a minimal example. I located the 
infinite loop inside the "two(I& i, J& j)" method of NaryUnion, and the 
reason seems to be that, after the call to "RangeList* t = range(j)" in 
the "else if" block (I unfortunately cannot give you line numbers as I 
messed around with print statements), "i.c" and "t" point to the very 
same RangeList (while they should not). I'm not expert enough to go 
deeper/further...

Notice that this appears only when region2 is created in a block (in 
real code, it would be inside a "for" or a "if"), however there is no 
influence if it is actually used or not.

I guess it is again related to the Region implementation that is going 
to change, but I think it is worth mentioning it anyway.

Jean-Noël


#include "gecode/driver.hh"
#include "gecode/iter.hh"
using namespace Gecode;
class MySpace:public Space {
public:
     virtual Space* copy(bool share){return this;}
};
int main(int argc, char* argv[]){
     MySpace home;
     Iter::Ranges::Singleton dom0(3,3);
     Iter::Ranges::Singleton dom1(1,1);
     Region region1(home);
     Iter::Ranges::NaryUnion u0;
     {
         Region region2(home);
         u0 = Iter::Ranges::NaryUnion(region2,dom0);//or using region1
     }
     Iter::Ranges::NaryUnion u1(region1,u0,dom1); //loops forever
     /*or
      * Region region3(home);
      * Iter::Ranges::NaryUnion u1(region3,u0,dom1);
      */
     return 0;
}