ignore false edges in emptiness checks and scc_info

Based on reports by Florian Renkin and Jens Kreber.

* spot/twaalgos/bfssteps.cc, spot/twaalgos/couvreurnew.cc,
spot/twaalgos/gtec/gtec.cc, spot/twaalgos/gv04.cc,
spot/twaalgos/magic.cc, spot/twaalgos/sccinfo.cc
spot/twaalgos/se05.cc, spot/twaalgos/tau03.cc: Ignore bddfalse edges.
* spot/twaalgos/gtec/gtec.hh: Remove debugging function.
* tests/core/neverclaimread.test: Adjust.
* tests/python/ecfalse.py: New test file.
* tests/Makefile.am: Add it.
* NEWS: Mention the bug.

tests/python/ecfalse.py

@@ -0,0 +1,86 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2020 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
+from buddy import bddfalse, bddtrue
+
+a = spot.automaton("""
+HOA: v1
+States: 2
+Start: 1
+AP: 2 "p0" "p1"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+--BODY--
+State: 0
+[!0 | 1] 0 {0}
+[0&!1] 1
+State: 1
+/* we want this edge to be false, but the parser
+   would ignore it if we wrote it here */
+[0] 0 {0}
+[!1] 1
+--END--
+""")
+# Make the false edge.
+for e in a.out(1):
+    if e.dst == 0:
+        e.cond = bddfalse
+
+assert a.accepting_run() is None
+assert a.is_empty()
+
+for name in ['SE05', 'CVWY90', 'GV04', 'Cou99(shy)', 'Cou99', 'Tau03']:
+    print(name)
+    ec = spot.make_emptiness_check_instantiator(name)[0].instantiate(a)
+    res = ec.check()
+    if res is not None:
+        print(res.accepting_run())
+    assert res is None
+
+si = spot.scc_info(a)
+assert si.scc_count() == 1 # only one accessible SCC
+a.set_init_state(0)
+si = spot.scc_info(a)
+assert si.scc_count() == 2
+
+a = spot.automaton("""HOA: v1 States: 11 Start: 0 AP: 2 "a" "b" Acceptance: 8
+(Fin(0) | Inf(1)) & (Fin(2) | Inf(3)) & ((Fin(4) & Inf(5)) | (Fin(6) & Inf(7)))
+properties: trans-labels explicit-labels trans-acc --BODY-- State: 0 [!0&!1] 1
+{0 4 6 7} [!0&!1] 2 {0 5 6} [!0&!1] 3 {3 4 6 7} [!0&!1] 4 {3 5 6} State: 1
+[0&1] 5 {2 5 7} [0&1] 6 {2 7} [0&1] 7 {2 3 5 7} [0&1] 8 {2 3 7} [0&1] 0 {2 5 7}
+[0&1] 9 {2 7} State: 2 [0&1] 1 {2} [0&1] 3 {2 3} [0&1] 10 {2} State: 3 [0&1] 0
+{3 5 7} [0&1] 9 {3 7} State: 4 [!0&!1] 5 {4 6} [!0&!1] 6 {7} [0&1] 10 {3}
+State: 5 State: 6 State: 7 [!0&!1] 1 {4 6 7} [!0&!1] 2 {5 6} State: 8 [!0&!1] 2
+{4} State: 9 [!0&!1] 2 {0 4} [!0&!1] 4 {3 4} State: 10 --END-- """)
+
+r = a.accepting_run()
+assert r is not None
+assert r.replay(spot.get_cout())
+for e in a.out(7):
+    if e.dst == 2:
+        e.cond = bddfalse
+s = a.accepting_run()
+assert s is not None
+assert s.replay(spot.get_cout())
+for e in a.out(2):
+    if e.dst == 1:
+        e.cond = bddfalse
+s = a.accepting_run()
+assert s is None