sccinfo: fix generation of self-loop accepting runs

Reported by Juraj Major.

* spot/twaalgos/sccinfo.cc (scc_info::get_accepting_run): Do not
assume TRACK_STATES is enabled.
* tests/core/autcross5.test: New file.
* tests/Makefile.am: Add it.
* NEWS: Mention the bug.

NEWS

@@ -12,6 +12,12 @@ New in spot 2.8.6.dev (not yet released)
   - autfilt --uniq was not considering differences in acceptance
     conditions or number of states when discarding automata.
 
+  - In an automaton with acceptance condition containing some Fin, and
+    whose accepting cycle could be reduced to a self-loop in an
+    otherwise larger SCC, the generation of an accepting run could be
+    wrong.  This could in turn cause segfaults or infinite loops while
+    running autcross or autfilt --stats=%w.
+
 New in spot 2.8.6 (2020-02-19)
 
   Bugs fixed:

spot/twaalgos/sccinfo.cc

 // -*- coding: utf-8 -*-
-// Copyright (C) 2014-2019 Laboratoire de Recherche et Développement
+// Copyright (C) 2014-2020 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
@@ -558,37 +558,43 @@ namespace spot
                   };
 
     // The SCC exploration has a small optimization that can flag SCCs
-    // has accepting if they contain accepting self-loops, even if the
+    // as accepting if they contain accepting self-loops, even if the
     // SCC itself has some Fin acceptance to check.  So we have to
     // deal with this situation before we look for the more complex
     // case of satisfying the condition with a larger cycle.  We do
     // this first, because it's good to return a small cycle if we
     // can.
     const acc_cond& acccond = aut_->acc();
-    for (unsigned s: node.states())
-      for (auto& e: aut_->out(s))
-        if (e.src == e.dst && !filter(e) && acccond.accepting(e.acc))
-          {
-            // We have found an accepting self-loop.  That's the cycle
-            // part of our accepting run.
-            r->cycle.clear();
-            r->cycle.emplace_front(aut_->state_from_number(e.src),
-                                   e.cond, e.acc);
-            // Add the prefix.
-            r->prefix.clear();
-            if (e.src != init)
-              explicit_bfs_steps(aut_, init, r->prefix,
-                                 [](const twa_graph::edge_storage_t&)
-                                 {
-                                   return false; // Do not filter.
-                                 },
-                                 [&](const twa_graph::edge_storage_t& t)
-                                 {
-                                   return t.dst == e.src;
-                                 });
-            return;
-          }
-
+    unsigned num_states = aut_->num_states();
+    for (unsigned s = 0; s < num_states; ++s)
+      {
+        // We scan the entire state to find those in the SCC, because
+        // we cannot rely on TRACK_STATES being on.
+        if (scc_of(s) != scc)
+          continue;
+        for (auto& e: aut_->out(s))
+          if (e.src == e.dst && !filter(e) && acccond.accepting(e.acc))
+            {
+              // We have found an accepting self-loop.  That's the cycle
+              // part of our accepting run.
+              r->cycle.clear();
+              r->cycle.emplace_front(aut_->state_from_number(e.src),
+                                     e.cond, e.acc);
+              // Add the prefix.
+              r->prefix.clear();
+              if (e.src != init)
+                explicit_bfs_steps(aut_, init, r->prefix,
+                                   [](const twa_graph::edge_storage_t&)
+                                   {
+                                     return false; // Do not filter.
+                                   },
+                                   [&](const twa_graph::edge_storage_t& t)
+                                   {
+                                     return t.dst == e.src;
+                                   });
+              return;
+            }
+      }
 
     // Prefix search
 

tests/Makefile.am

@@ -314,6 +314,7 @@ TESTS_twa = \
   core/autcross2.test \
   core/autcross3.test \
   core/autcross4.test \
+  core/autcross5.test \
   core/complementation.test \
   core/randpsl.test \
   core/cycles.test \

tests/core/autcross5.test

+#!/bin/sh
+# -*- 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/>.
+
+. ./defs
+set -e
+
+# Based on a report by Juraj Major.
+
+cat >a7.hoa <<EOF
+HOA: v1 States: 34 Start: 0 AP: 5 "a" "b" "c" "d" "e" Acceptance:
+7 (Fin(1) | Inf(2)) & (Fin(0) | Inf(5)) & (Inf(3)&Inf(4)&Inf(6))
+properties: trans-labels explicit-labels trans-acc --BODY-- State:
+0 [1&!2&4] 1 [0&1&2 | 1&!2&!4 | 1&2&3] 2 [!0&1&2&!3&4] 3 [0&1&2&4 |
+1&2&3&4] 4 [!0&1&2&!3&!4] 5 [0&1&2&!4 | 1&2&3&!4] 6 [!1&!2&!4] 7 [!1&2&!4]
+8 [!1&2&4] 9 [1&2&!4] 10 [0&1&2&!4 | 1&2&3&!4] 11 [!1&2&!4] 12 [!1&!2] 13
+[0&!1&2 | !1&2&3] 14 State: 1 [1&!2&4] 1 {3 4 6} [0&1&2&!4 | 1&2&3&!4]
+2 {6} [0&1&2&4 | 1&2&3&4] 2 {3 6} [1&!2&!4] 2 {4 6} [!0&1&2&!3&4]
+3 {3 6} [0&1&2&4 | 1&2&3&4] 4 {3 6} [!0&1&2&!3&!4] 5 {6} [0&1&2&!4 |
+1&2&3&!4] 6 {6} [1&2&!4] 10 [0&1&2&!4 | 1&2&3&!4] 11 State: 2 [1&!2&4]
+1 {3 4 6} [0&1&2&!4 | 1&2&3&!4] 2 {6} [0&1&2&4 | 1&2&3&4] 2 {3 6}
+[1&!2&!4] 2 {4 6} [!0&1&2&!3&4] 3 {3 6} [0&1&2&4 | 1&2&3&4] 4 {3 6}
+[!0&1&2&!3&!4] 5 {6} [0&1&2&!4 | 1&2&3&!4] 6 {6} State: 3 [1&!2&4]
+1 {3 4 6} [0&1&2&!4 | 1&2&3&!4] 2 {6} [0&1&2&4 | 1&2&3&4] 2 {3 6}
+[1&!2&!4] 2 {4 6} [!0&1&2&!3&4] 3 {3 6} [0&1&2&4 | 1&2&3&4] 4 {3 6}
+[!0&1&2&!3&!4] 5 {6} [0&1&2&!4 | 1&2&3&!4] 6 {6} [!1&!2&!4] 7 [!1&2&!4]
+8 [!1&!2] 13 [0&!1&2 | !1&2&3] 15 State: 4 [!0&1&!2&!3&4] 1 {3 4 5 6}
+[!0&1&!2&!3&!4] 2 {4 5 6} [!0&1&2&!3&4] 3 {3 5 6} [!0&1&2&!3&!4] 5 {5 6}
+[!0&!1&!2&!3&!4] 7 [!0&!1&2&!3&!4] 8 [!0&!1&!2&!3] 13 [!0&1&!2&3&4] 16
+{3 4 6} [0&1&!2&4] 16 {0 3 4 6} [!0&1&!2&3&!4] 17 {4 6} [0&1&!2&!4] 17
+{0 4 6} [0&!1&!2&!4 | !1&!2&3&!4] 18 [0&!1&!2 | !1&!2&3] 19 [0&!1&2&!4 |
+!1&2&3&!4] 20 State: 5 [1&!2&4] 1 {3 4 6} [0&1&2&!4 | 1&2&3&!4] 2 {6}
+[0&1&2&4 | 1&2&3&4] 2 {3 6} [1&!2&!4] 2 {4 6} [!0&1&2&!3&4] 3 {3 6}
+[0&1&2&4 | 1&2&3&4] 4 {3 6} [!0&1&2&!3&!4] 5 {6} [0&1&2&!4 | 1&2&3&!4]
+6 {6} [!1&!2&4] 13 [0&!1&2&4 | !1&2&3&4] 15 [!1&!2&!4] 21 [0&!1&2&!4 |
+!1&2&3&!4] 22 State: 6 [!0&1&!2&!3&4] 1 {3 4 5 6} [!0&1&!2&!3&!4] 2 {4
+5 6} [!0&1&2&!3&4] 3 {3 5 6} [!0&1&2&!3&!4] 5 {5 6} [!0&!1&!2&!3&4] 13
+[!0&1&!2&3&4] 16 {3 4 6} [0&1&!2&4] 16 {0 3 4 6} [!0&1&!2&3&!4] 17 {4 6}
+[0&1&!2&!4] 17 {0 4 6} [0&!1&!2&4 | !1&!2&3&4] 19 [!0&!1&!2&!3&!4] 21
+[0&!1&!2&!4 | !1&!2&3&!4] 23 State: 7 [!1&!2&!4] 7 {3 4 6} [!1&2&!4]
+8 {3 6} [1&2&!4] 10 [0&1&2&!4 | 1&2&3&!4] 11 [0&!1&2&!4 | !1&2&3&!4]
+24 State: 8 [!1&!2&!4] 7 {3 4 6} [!1&2&!4] 8 {3 6} State: 9 [!1&2&4] 9
+{3 4 6} [1&2&!4] 10 [0&1&2&!4 | 1&2&3&!4] 11 [!1&2&!4] 12 {4 6} [0&!1&2 |
+!1&2&3] 25 State: 10 [1&2&!4] 10 {3 4 6} [0&1&2&!4 | 1&2&3&!4] 11 {3 4 6}
+State: 11 [!0&1&2&!3&!4] 10 {3 4 5 6} [!0&1&2&3&!4] 11 {3 4 6} [0&1&2&!4]
+11 {0 3 4 6} State: 12 [!1&2&4] 9 {3 4 6} [!1&2&!4] 12 {4 6} State: 13
+[!1&!2&!4] 7 [!1&2&!4] 8 [!1&2&4] 9 [!1&2&!4] 12 [!1&!2] 13 [0&!1&2 |
+!1&2&3] 14 State: 14 [0&!1] 14 [!0&!1&3] 14 {1} [0&!1&!2&!4 | !1&!2&3&!4]
+26 [0&!1&2&!4 | !1&2&3&!4] 27 [0&!1&2&4 | !1&2&3&4] 28 [0&!1&2&!4 |
+!1&2&3&!4] 29 State: 15 [0&!1&!2 | !1&!2&3] 14 [0&!1&2] 15 [!0&!1&2&3]
+15 {1} [0&!1&!2&!4 | !1&!2&3&!4] 26 [0&!1&2&!4 | !1&2&3&!4] 27 State:
+16 [!0&1&!2&!3&4] 1 {3 4 5 6} [!0&1&!2&!3&!4] 2 {4 5 6} [!0&1&2&!3&4]
+3 {3 5 6} [!0&1&2&!3&!4] 5 {5 6} [!0&1&2&!3&!4] 10 [!0&1&!2&3&4] 16
+{3 4 6} [0&1&!2&4] 16 {0 3 4 6} [!0&1&!2&3&!4] 17 {4 6} [0&1&!2&!4] 17
+{0 4 6} State: 17 [!0&1&!2&!3&4] 1 {3 4 5 6} [!0&1&!2&!3&!4] 2 {4 5 6}
+[!0&1&2&!3&4] 3 {3 5 6} [!0&1&2&!3&!4] 5 {5 6} [!0&1&!2&3&4] 16 {3 4 6}
+[0&1&!2&4] 16 {0 3 4 6} [!0&1&!2&3&!4] 17 {4 6} [0&1&!2&!4] 17 {0 4 6}
+State: 18 [!0&!1&!2&!3&!4] 7 [!0&!1&2&!3&!4] 8 [!0&1&2&!3&!4] 10 [0&1&2&!4
+| 1&2&3&!4] 11 [!0&!1&!2&3&!4] 18 {3 4 6} [0&!1&!2&!4] 18 {0 3 4 6}
+[!0&!1&2&3&!4] 20 {3 6} [0&!1&2&!4] 20 {0 3 6} State: 19 [!0&!1&!2&!3&!4]
+7 [!0&!1&2&!3&!4] 8 [!0&!1&2&!3&4] 9 [!0&!1&2&!3&!4] 12 [!0&!1&!2&!3] 13
+[0&!1&!2&!4 | !1&!2&3&!4] 18 [!0&!1&!2&3] 19 [0&!1&!2] 19 {0} [0&!1&2&!4 |
+!1&2&3&!4] 20 [0&!1&2&4 | !1&2&3&4] 30 [0&!1&2&!4 | !1&2&3&!4] 31 State:
+20 [!0&!1&!2&!3&!4] 7 [!0&!1&2&!3&!4] 8 [!0&!1&!2&3&!4] 18 {3 4 6}
+[0&!1&!2&!4] 18 {0 3 4 6} [!0&!1&2&3&!4] 20 {3 6} [0&!1&2&!4] 20 {0 3 6}
+State: 21 [!1&2&4] 9 [!1&2&!4] 12 [!1&!2&4] 13 [0&!1&2&4 | !1&2&3&4] 14
+[!1&!2&!4] 21 [0&!1&2&!4 | !1&2&3&!4] 32 State: 22 [0&!1&!2&4 | !1&!2&3&4]
+14 [0&!1&2&4 | !1&2&3&4] 15 [0&!1&2&!4] 22 [!0&!1&2&3&!4] 22 {1}
+[0&!1&!2&!4 | !1&!2&3&!4] 32 State: 23 [!0&!1&2&!3&4] 9 [!0&!1&2&!3&!4]
+12 [!0&!1&!2&!3&4] 13 [0&!1&!2&4 | !1&!2&3&4] 19 [!0&!1&!2&!3&!4] 21
+[!0&!1&!2&3&!4] 23 [0&!1&!2&!4] 23 {0} [0&!1&2&4 | !1&2&3&4] 30 [0&!1&2&!4
+| !1&2&3&!4] 31 State: 24 [!0&!1&2&3&!4] 24 {1 3 4} [0&!1&2&!4] 24 {2 3 4}
+[!0&!1&!2&3&!4] 26 {1 3 4 6} [0&!1&!2&!4] 26 {2 3 4 6} [!0&!1&2&3&!4]
+27 {1 3 6} [0&!1&2&!4] 27 {2 3 6} State: 25 [!0&!1&2&3&!4] 25 {1 3 4}
+[0&!1&2&!4] 25 {2 3 4} [!0&!1&2&3&4] 28 {1 3 4 6} [0&!1&2&4] 28 {2
+3 4 6} [!0&!1&2&3&!4] 29 {1 4 6} [0&!1&2&!4] 29 {2 4 6} State: 26
+[!0&!1&2&3&!4] 24 {1 3 4} [0&!1&2&!4] 24 {2 3 4} [!0&!1&!2&3&!4] 26 {1
+3 4 6} [0&!1&!2&!4] 26 {2 3 4 6} [!0&!1&2&3&!4] 27 {1 3 6} [0&!1&2&!4]
+27 {2 3 6} [0&1&2&!4 | 1&2&3&!4] 33 State: 27 [!0&!1&!2&3&!4] 26 {1 3 4 6}
+[0&!1&!2&!4] 26 {2 3 4 6} [!0&!1&2&3&!4] 27 {1 3 6} [0&!1&2&!4] 27 {2 3 6}
+State: 28 [!0&!1&2&3&!4] 25 {1 3 4} [0&!1&2&!4] 25 {2 3 4} [!0&!1&2&3&4]
+28 {1 3 4 6} [0&!1&2&4] 28 {2 3 4 6} [!0&!1&2&3&!4] 29 {1 4 6} [0&!1&2&!4]
+29 {2 4 6} [0&1&2&!4 | 1&2&3&!4] 33 State: 29 [!0&!1&2&3&4] 28 {1 3 4 6}
+[0&!1&2&4] 28 {2 3 4 6} [!0&!1&2&3&!4] 29 {1 4 6} [0&!1&2&!4] 29 {2 4
+6} State: 30 [!0&!1&2&!3&4] 9 [!0&1&2&!3&!4] 10 [0&1&2&!4 | 1&2&3&!4]
+11 [!0&!1&2&!3&!4] 12 [!0&!1&2&3&4] 30 {3 4 6} [0&!1&2&4] 30 {0 3 4 6}
+[!0&!1&2&3&!4] 31 {4 6} [0&!1&2&!4] 31 {0 4 6} State: 31 [!0&!1&2&!3&4]
+9 [!0&!1&2&!3&!4] 12 [!0&!1&2&3&4] 30 {3 4 6} [0&!1&2&4] 30 {0 3 4 6}
+[!0&!1&2&3&!4] 31 {4 6} [0&!1&2&!4] 31 {0 4 6} State: 32 [0&!1&4 |
+!1&3&4] 14 [0&!1&2&4 | !1&2&3&4] 28 [0&!1&2&!4 | !1&2&3&!4] 29 [0&!1&!4]
+32 [!0&!1&3&!4] 32 {1} State: 33 [!0&1&2&3&!4] 33 {1 3 4 6} [0&1&2&!4]
+33 {2 3 4 6} --END--
+EOF
+
+cat >_a7.hoa <<EOF
+HOA: v1 States: 34 Start: 0 AP: 5 "a" "b" "c" "d" "e" Acceptance:
+6 (Fin(0) & (Inf(1)&Inf(2))) | (Inf(3)&Inf(4)&Inf(5)) properties:
+trans-labels explicit-labels trans-acc --BODY-- State: 0 [1&!2&4]
+1 [0&1&2 | 1&!2&!4 | 1&2&3] 2 [!0&1&2&!3&4] 3 [0&1&2&4 | 1&2&3&4]
+4 [!0&1&2&!3&!4] 5 [0&1&2&!4 | 1&2&3&!4] 6 [!1&!2&!4] 7 [!1&2&!4] 8
+[!1&2&4] 9 [1&2&!4] 10 [0&1&2&!4 | 1&2&3&!4] 11 [!1&2&!4] 12 [!1&!2] 13
+[0&!1&2 | !1&2&3] 14 State: 1 [1&!2&4] 1 {1 2 3 4} [0&1&2&!4 | 1&2&3&!4]
+2 [0&1&2&4 | 1&2&3&4] 2 {1 3} [1&!2&!4] 2 {2 4} [!0&1&2&!3&4] 3 {1 3}
+[0&1&2&4 | 1&2&3&4] 4 {1 3} [!0&1&2&!3&!4] 5 [0&1&2&!4 | 1&2&3&!4]
+6 [1&2&!4] 10 [0&1&2&!4 | 1&2&3&!4] 11 State: 2 [1&!2&4] 1 {1 2 3 4}
+[0&1&2&!4 | 1&2&3&!4] 2 [0&1&2&4 | 1&2&3&4] 2 {1 3} [1&!2&!4] 2 {2 4}
+[!0&1&2&!3&4] 3 {1 3} [0&1&2&4 | 1&2&3&4] 4 {1 3} [!0&1&2&!3&!4]
+5 [0&1&2&!4 | 1&2&3&!4] 6 State: 3 [1&!2&4] 1 {1 2 3 4} [0&1&2&!4 |
+1&2&3&!4] 2 [0&1&2&4 | 1&2&3&4] 2 {1 3} [1&!2&!4] 2 {2 4} [!0&1&2&!3&4] 3
+{1 3} [0&1&2&4 | 1&2&3&4] 4 {1 3} [!0&1&2&!3&!4] 5 [0&1&2&!4 | 1&2&3&!4]
+6 [!1&!2&!4] 7 [!1&2&!4] 8 [!1&!2] 13 [0&!1&2 | !1&2&3] 15 State: 4
+[!0&1&!2&!3&4] 1 {1 2 3 4 5} [!0&1&!2&!3&!4] 2 {2 4 5} [!0&1&2&!3&4]
+3 {1 3 5} [!0&1&2&!3&!4] 5 {5} [!0&!1&!2&!3&!4] 7 [!0&!1&2&!3&!4] 8
+[!0&!1&!2&!3] 13 [!0&1&!2&3&4] 16 {1 2 3 4} [0&1&!2&4] 16 {0 1 2 3 4}
+[!0&1&!2&3&!4] 17 {2 4} [0&1&!2&!4] 17 {0 2 4} [0&!1&!2&!4 | !1&!2&3&!4]
+18 [0&!1&!2 | !1&!2&3] 19 [0&!1&2&!4 | !1&2&3&!4] 20 State: 5 [1&!2&4]
+1 {1 2 3 4} [0&1&2&!4 | 1&2&3&!4] 2 [0&1&2&4 | 1&2&3&4] 2 {1 3} [1&!2&!4]
+2 {2 4} [!0&1&2&!3&4] 3 {1 3} [0&1&2&4 | 1&2&3&4] 4 {1 3} [!0&1&2&!3&!4] 5
+[0&1&2&!4 | 1&2&3&!4] 6 [!1&!2&4] 13 [0&!1&2&4 | !1&2&3&4] 15 [!1&!2&!4]
+21 [0&!1&2&!4 | !1&2&3&!4] 22 State: 6 [!0&1&!2&!3&4] 1 {1 2 3 4 5}
+[!0&1&!2&!3&!4] 2 {2 4 5} [!0&1&2&!3&4] 3 {1 3 5} [!0&1&2&!3&!4]
+5 {5} [!0&!1&!2&!3&4] 13 [!0&1&!2&3&4] 16 {1 2 3 4} [0&1&!2&4] 16 {0
+1 2 3 4} [!0&1&!2&3&!4] 17 {2 4} [0&1&!2&!4] 17 {0 2 4} [0&!1&!2&4 |
+!1&!2&3&4] 19 [!0&!1&!2&!3&!4] 21 [0&!1&!2&!4 | !1&!2&3&!4] 23 State:
+7 [!1&!2&!4] 7 {1 2} [!1&2&!4] 8 {2} [1&2&!4] 10 [0&1&2&!4 | 1&2&3&!4]
+11 [0&!1&2&!4 | !1&2&3&!4] 24 State: 8 [!1&!2&!4] 7 {1 2} [!1&2&!4]
+8 {2} State: 9 [!1&2&4] 9 {1 2} [1&2&!4] 10 [0&1&2&!4 | 1&2&3&!4] 11
+[!1&2&!4] 12 {2} [0&!1&2 | !1&2&3] 25 State: 10 [1&2&!4] 10 {1 2 4 5}
+[0&1&2&!4 | 1&2&3&!4] 11 {1 2 4 5} State: 11 [!0&1&2&!3&!4] 10 {1 2 3 4 5}
+[!0&1&2&3&!4] 11 {1 2 4 5} [0&1&2&!4] 11 {0 1 2 4 5} State: 12 [!1&2&4]
+9 {1 2} [!1&2&!4] 12 {2} State: 13 [!1&!2&!4] 7 [!1&2&!4] 8 [!1&2&4] 9
+[!1&2&!4] 12 [!1&!2] 13 [0&!1&2 | !1&2&3] 14 State: 14 [0&!1] 14 [!0&!1&3]
+14 [0&!1&!2&!4 | !1&!2&3&!4] 26 [0&!1&2&!4 | !1&2&3&!4] 27 [0&!1&2&4 |
+!1&2&3&4] 28 [0&!1&2&!4 | !1&2&3&!4] 29 State: 15 [0&!1&!2 | !1&!2&3]
+14 [0&!1&2] 15 [!0&!1&2&3] 15 [0&!1&!2&!4 | !1&!2&3&!4] 26 [0&!1&2&!4 |
+!1&2&3&!4] 27 State: 16 [!0&1&!2&!3&4] 1 {1 2 3 4 5} [!0&1&!2&!3&!4]
+2 {2 4 5} [!0&1&2&!3&4] 3 {1 3 5} [!0&1&2&!3&!4] 5 {5} [!0&1&2&!3&!4]
+10 [!0&1&!2&3&4] 16 {1 2 3 4} [0&1&!2&4] 16 {0 1 2 3 4} [!0&1&!2&3&!4]
+17 {2 4} [0&1&!2&!4] 17 {0 2 4} State: 17 [!0&1&!2&!3&4] 1 {1 2 3 4 5}
+[!0&1&!2&!3&!4] 2 {2 4 5} [!0&1&2&!3&4] 3 {1 3 5} [!0&1&2&!3&!4] 5 {5}
+[!0&1&!2&3&4] 16 {1 2 3 4} [0&1&!2&4] 16 {0 1 2 3 4} [!0&1&!2&3&!4] 17 {2
+4} [0&1&!2&!4] 17 {0 2 4} State: 18 [!0&!1&!2&!3&!4] 7 [!0&!1&2&!3&!4]
+8 [!0&1&2&!3&!4] 10 [0&1&2&!4 | 1&2&3&!4] 11 [!0&!1&!2&3&!4] 18 {1 2}
+[0&!1&!2&!4] 18 {0 1 2} [!0&!1&2&3&!4] 20 {2} [0&!1&2&!4] 20 {0 2} State:
+19 [!0&!1&!2&!3&!4] 7 [!0&!1&2&!3&!4] 8 [!0&!1&2&!3&4] 9 [!0&!1&2&!3&!4]
+12 [!0&!1&!2&!3] 13 [0&!1&!2&!4 | !1&!2&3&!4] 18 [!0&!1&!2&3] 19
+[0&!1&!2] 19 [0&!1&2&!4 | !1&2&3&!4] 20 [0&!1&2&4 | !1&2&3&4] 30
+[0&!1&2&!4 | !1&2&3&!4] 31 State: 20 [!0&!1&!2&!3&!4] 7 [!0&!1&2&!3&!4]
+8 [!0&!1&!2&3&!4] 18 {1 2} [0&!1&!2&!4] 18 {0 1 2} [!0&!1&2&3&!4] 20 {2}
+[0&!1&2&!4] 20 {0 2} State: 21 [!1&2&4] 9 [!1&2&!4] 12 [!1&!2&4] 13
+[0&!1&2&4 | !1&2&3&4] 14 [!1&!2&!4] 21 [0&!1&2&!4 | !1&2&3&!4] 32 State:
+22 [0&!1&!2&4 | !1&!2&3&4] 14 [0&!1&2&4 | !1&2&3&4] 15 [0&!1&2&!4] 22
+[!0&!1&2&3&!4] 22 [0&!1&!2&!4 | !1&!2&3&!4] 32 State: 23 [!0&!1&2&!3&4]
+9 [!0&!1&2&!3&!4] 12 [!0&!1&!2&!3&4] 13 [0&!1&!2&4 | !1&!2&3&4] 19
+[!0&!1&!2&!3&!4] 21 [!0&!1&!2&3&!4] 23 [0&!1&!2&!4] 23 [0&!1&2&4 |
+!1&2&3&4] 30 [0&!1&2&!4 | !1&2&3&!4] 31 State: 24 [!0&!1&2&3&!4]
+24 {0 1 2 4} [0&!1&2&!4] 24 {1 2 3 4} [!0&!1&!2&3&!4] 26 {0 1 2 4 5}
+[0&!1&!2&!4] 26 {1 2 3 4 5} [!0&!1&2&3&!4] 27 {0 1 2 5} [0&!1&2&!4] 27
+{1 2 3 5} State: 25 [!0&!1&2&3&!4] 25 {0 1 2 4} [0&!1&2&!4] 25 {1 2 3 4}
+[!0&!1&2&3&4] 28 {0 1 2 4 5} [0&!1&2&4] 28 {1 2 3 4 5} [!0&!1&2&3&!4] 29
+{0 1 2 5} [0&!1&2&!4] 29 {1 2 3 5} State: 26 [!0&!1&2&3&!4] 24 {0 1 2 4}
+[0&!1&2&!4] 24 {1 2 3 4} [!0&!1&!2&3&!4] 26 {0 1 2 4 5} [0&!1&!2&!4] 26 {1
+2 3 4 5} [!0&!1&2&3&!4] 27 {0 1 2 5} [0&!1&2&!4] 27 {1 2 3 5} [0&1&2&!4
+| 1&2&3&!4] 33 State: 27 [!0&!1&!2&3&!4] 26 {0 1 2 4 5} [0&!1&!2&!4] 26
+{1 2 3 4 5} [!0&!1&2&3&!4] 27 {0 1 2 5} [0&!1&2&!4] 27 {1 2 3 5} State:
+28 [!0&!1&2&3&!4] 25 {0 1 2 4} [0&!1&2&!4] 25 {1 2 3 4} [!0&!1&2&3&4]
+28 {0 1 2 4 5} [0&!1&2&4] 28 {1 2 3 4 5} [!0&!1&2&3&!4] 29 {0 1 2 5}
+[0&!1&2&!4] 29 {1 2 3 5} [0&1&2&!4 | 1&2&3&!4] 33 State: 29 [!0&!1&2&3&4]
+28 {0 1 2 4 5} [0&!1&2&4] 28 {1 2 3 4 5} [!0&!1&2&3&!4] 29 {0 1 2 5}
+[0&!1&2&!4] 29 {1 2 3 5} State: 30 [!0&!1&2&!3&4] 9 [!0&1&2&!3&!4]
+10 [0&1&2&!4 | 1&2&3&!4] 11 [!0&!1&2&!3&!4] 12 [!0&!1&2&3&4] 30 {1 2}
+[0&!1&2&4] 30 {0 1 2} [!0&!1&2&3&!4] 31 {2} [0&!1&2&!4] 31 {0 2} State:
+31 [!0&!1&2&!3&4] 9 [!0&!1&2&!3&!4] 12 [!0&!1&2&3&4] 30 {1 2} [0&!1&2&4]
+30 {0 1 2} [!0&!1&2&3&!4] 31 {2} [0&!1&2&!4] 31 {0 2} State: 32 [0&!1&4 |
+!1&3&4] 14 [0&!1&2&4 | !1&2&3&4] 28 [0&!1&2&!4 | !1&2&3&!4] 29 [0&!1&!4]
+32 [!0&!1&3&!4] 32 State: 33 [!0&1&2&3&!4] 33 {0 1 2 4 5} [0&1&2&!4]
+33 {1 2 3 4 5} --END--
+EOF
+
+# The following command used to do segfault or loop infinitely
+# due to an incorrectly generated counterexample.
+autcross -F a7.hoa 'autfilt' ': %H && cat _a7.hoa > %O' 2>stderr && exit 2
+cat stderr
+grep 'both automata accept the infinite word:' stderr