emptiness checks: replace assert-preconditions by exceptions

* spot/twaalgos/couvreurnew.cc, spot/twaalgos/gv04.cc,
spot/twaalgos/magic.cc, spot/twaalgos/se05.cc, spot/twaalgos/tau03.cc,
spot/twaalgos/tau03opt.cc: Throw if precondition on acceptance
condition is not satisfied.
* tests/python/misc-ec.py: New file.
* tests/Makefile.am: Add it.
* NEWS: Mention the change.

NEWS

@@ -54,6 +54,11 @@ New in spot 2.3.1.dev (not yet released)
   - the Python wrappers for spot::twa_graph::state_from_number and
     spot::twa_graph::state_acc_sets were broken in 2.3.
 
+  - instantiating an emptiness check on an automaton with unsupported
+    acceptance condition should throw an exception.  This used to be
+    just an assertion, disabled in release builds; the difference
+    matters for the Python bindings.
+
   Deprecation notices:
 
   - Using --format=%a to print the number of atomic propositions in

spot/twaalgos/couvreurnew.cc

@@ -540,12 +540,17 @@ namespace spot
         : emptiness_check(a, o)
         , ecs_(std::make_shared<couvreur99_new_status<is_explicit>>(a))
       {
+        if (a->acc().uses_fin_acceptance())
+          throw std::runtime_error
+            ("couvreur99_new requires Fin-less acceptance");
       }
 
       virtual
       emptiness_check_result_ptr
       check() override
       {
+        if (ecs_->aut->acc().get_acceptance().is_f())
+          return nullptr;
         return check_impl<true>();
       }
 

spot/twaalgos/gv04.cc

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2008, 2010, 2011, 2013, 2014, 2015, 2016 Laboratoire de
+// Copyright (C) 2008, 2010, 2011, 2013-2017 Laboratoire de
 // recherche et développement de l'Epita (LRDE).
 // Copyright (C) 2004, 2005 Laboratoire d'Informatique de Paris 6
 // (LIP6), département Systèmes Répartis Coopératifs (SRC), Université
@@ -67,7 +67,11 @@ namespace spot
       gv04(const const_twa_ptr& a, option_map o)
         : emptiness_check(a, o)
       {
-        assert(a->num_sets() <= 1);
+        if (!(a->prop_weak().is_true()
+              || a->num_sets() == 0
+              || a->acc().is_buchi()))
+          throw std::runtime_error
+            ("gv04 requires Büchi or weak automata");
       }
 
       ~gv04()

spot/twaalgos/magic.cc

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2011, 2013, 2014, 2015, 2016 Laboratoire de recherche et
+// Copyright (C) 2011, 2013-2017  Laboratoire de recherche et
 // développement de l'Epita (LRDE).
 // Copyright (C) 2004, 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
@@ -59,7 +59,11 @@ namespace spot
         : emptiness_check(a, o),
           h(size)
       {
-        assert(a->num_sets() <= 1);
+        if (!(a->prop_weak().is_true()
+              || a->num_sets() == 0
+              || a->acc().is_buchi()))
+          throw std::runtime_error
+            ("magic_search requires Büchi or weak automata");
       }
 
       virtual ~magic_search_()

spot/twaalgos/se05.cc

@@ -1,6 +1,6 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2011, 2013, 2014, 2015, 2016 Laboratoire de Recherche
+// Copyright (C) 2011, 2013-2017  Laboratoire de Recherche et
-// et Développement de l'Epita (LRDE).
+// Développement de l'Epita (LRDE).
 // Copyright (C) 2004, 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
 // et Marie Curie.
@@ -59,7 +59,10 @@ namespace spot
         : emptiness_check(a, o),
           h(size)
       {
-        assert(a->num_sets() <= 1);
+        if (!(a->prop_weak().is_true()
+              || a->num_sets() == 0
+              || a->acc().is_buchi()))
+          throw std::runtime_error("se05 requires Büchi or weak automata");
       }
 
       virtual ~se05_search()

spot/twaalgos/tau03.cc

@@ -1,6 +1,6 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2011, 2013, 2014, 2015, 2016 Laboratoire de Recherche
+// Copyright (C) 2011, 2013-2017  Laboratoire de Recherche et
-// et Developpement de l'Epita (LRDE).
+// Developpement de l'Epita (LRDE).
 // Copyright (C) 2004, 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
 // et Marie Curie.
@@ -58,7 +58,9 @@ namespace spot
         : emptiness_check(a, o),
           h(size)
       {
-        assert(a->num_sets() > 0);
+        if (!(a->num_sets() > 0 && a->acc().is_generalized_buchi()))
+          throw std::runtime_error
+            ("tau03 requires generalized Büchi with at least one set");
       }
 
       virtual ~tau03_search()

spot/twaalgos/tau03opt.cc

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2011, 2013, 2014, 2015, 2016 Laboratoire de Recherche et
+// Copyright (C) 2011, 2013-2017  Laboratoire de Recherche et
 // Développement de l'Epita (LRDE).
 // Copyright (C) 2004, 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
@@ -74,6 +74,8 @@ namespace spot
           use_weights(o.get("weights", 1)),
           use_red_weights(use_weights && o.get("redweights", 1))
       {
+        if (a->acc().uses_fin_acceptance())
+          throw std::runtime_error("tau03opt requires Fin-less acceptance");
       }
 
       virtual ~tau03_opt_search()

tests/Makefile.am

@@ -339,6 +339,7 @@ TESTS_python = \
   python/ltlparse.py \
   python/ltlsimple.py \
   python/minato.py \
+  python/misc-ec.py \
   python/optionmap.py \
   python/otfcrash.py \
   python/parsetgba.py \

tests/python/misc-ec.py

@@ -0,0 +1,47 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2017 Laboratoire de Recherche et Développement de l'Epita
+# (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import spot
+aut = spot.translate("G(p0 | (p0 R Xp0) | XF(!p0 & p1))", 'BA')
+ec = spot.make_emptiness_check_instantiator('SE05')[0].instantiate(aut)
+n = 0
+while True:
+    res = ec.check()
+    if not res:
+        break
+    print(res.accepting_run())
+    n += 1
+assert n == 2
+
+for name in ['SE05', 'CVWY90', 'GV04']:
+    aut = spot.translate("GFa && GFb")
+    try:
+        ec = spot.make_emptiness_check_instantiator(name)[0].instantiate(aut)
+        print(ec.check().accepting_run())
+    except RuntimeError as e:
+        assert "Büchi or weak" in str(e)
+
+aut = spot.translate("a", 'monitor')
+try:
+    ec = spot.make_emptiness_check_instantiator('Tau03')[0].instantiate(aut)
+except RuntimeError as e:
+    assert "at least one" in str(e)
+
+aut = spot.translate("a", 'ba')
+ec = spot.make_emptiness_check_instantiator('Tau03')[0].instantiate(aut)