boostorg
time_duration is not a complete partial order regarding time_duration(not_a_date_time)
hi
please compile this program:
#include <boost/date_time/posix_time/ptime.hpp>
#include
using namespace boost::posix_time; using namespace std;
#define x(v) cout << #v << " : " << (v) << '\n';
int main(int argc, char *argv[])
{
time_duration a(not_a_date_time);
time_duration b;
x(a<b);
x(a>b);
x(a<=b);
x(a>=b);
x(b<a);
x(b>a);
x(b<=a);
x(b>=a);
x(a==b);
x(b==a);
x(a.is_special());
x(b.is_special());
vector<time_duration> v0, v1;
v0.push_back(time_duration());
v0.push_back(time_duration(not_a_date_time));
sort(v0.begin(), v0.end());
v1.push_back(time_duration(not_a_date_time));
v1.push_back(time_duration());
sort(v1.begin(), v1.end());
x(v0==v1);
map<time_duration, string> c,d; c[time_duration()]=5; c[time_duration(not_a_date_time)]=7; d[time_duration(not_a_date_time)]=7; d[time_duration()]=5; x(c==d);
return 0; }
the output is:
a<b : 0
a>b : 0
a<=b : 1
a>=b : 1
b<a : 0
b>a : 0
b<=a : 1
b>=a : 1
a==b : 0
b==a : 0
a.is_special() : 1
b.is_special() : 0
v0==v1 : 0
c==d : 0
if the time_duration datatype is a complete partial order which is for example needed for it to be able to be sorted, then the above output is partly illegal:
if not a<b and not b<a then must be a=b. but this is not the case.
if a<=b and b<=a then must be a=b. but this is not the case.
so as expected the two vectors v0 and v1 are not equal after being sorted even though they certainly should be!
also the maps c and d should be equal but aren't.
I hope that this is a bug and not a feature. otherwise it should be documented that even though ptime and gregorian::date are complete partial orders (also regarding their not_a_date_time special value), time_duration isn't. But I really strongly hope that this is a bug.
cya erik
Related ML thread: https://lists.boost.org/boost-users/2019/05/89805.php
It is odd that ptime treats not_a_date_time as an ordinary value and time_duration does not. The difference appears to be that one comparison operator goes through int_adapter and the other does not.
