python: fix binding of used_inf_fin_sets()

* python/spot/impl.i: Here.
* tests/python/setacc.py: Test it.
* NEWS: Mention the bug.

NEWS

@@ -75,6 +75,11 @@ New in spot 2.6.3.dev (not yet released)
     used to check whether a formula or an automaton represents a
     liveness property.
 
+  Bugs fixed:
+
+  - The pair of acc_cond::mark_t returned by
+    acc_code::used_inf_fin_sets() was not usable in Python.
+
 New in spot 2.6.3 (2018-10-17)
 
   Bugs fixed:

python/spot/impl.i

@@ -447,6 +447,7 @@ namespace swig
 namespace std {
   %template(liststr) list<std::string>;
   %template(pairunsigned) pair<unsigned, unsigned>;
+  %template(pairmark_t) pair<spot::acc_cond::mark_t, spot::acc_cond::mark_t>;
   %template(vectorformula) vector<spot::formula>;
   %template(vectorunsigned) vector<unsigned>;
   %template(vectorpairunsigned) vector<pair<unsigned, unsigned>>;

tests/python/setacc.py

@@ -18,10 +18,21 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# Test case reduced from a report from Juraj Major <major@fi.muni.cz>.
 import spot
+
+
+# Test case reduced from a report from Juraj Major <major@fi.muni.cz>.
 a = spot.make_twa_graph(spot._bdd_dict)
 a.set_acceptance(0, spot.acc_code("t"))
 assert(a.prop_state_acc() == True);
 a.set_acceptance(1, spot.acc_code("Fin(0)"))
 assert(a.prop_state_acc() == spot.trival.maybe());
+
+
+# Some tests for used_inf_fin_sets(), which return a pair of mark_t.
+(inf, fin) = a.get_acceptance().used_inf_fin_sets()
+assert inf == []
+assert fin == [0]
+(inf, fin) = spot.acc_code("(Fin(0)|Inf(1))&Fin(2)&Inf(0)").used_inf_fin_sets()
+assert inf == [0,1]
+assert fin == [0,2]