ltl2ta: fix a crash with --ta.

* src/taalgos/tgba2ta.cc: Do not assume the input is an sba.
* src/tgbatest/ltl2ta2.test: New file.
* src/tgbatest/Makefile.am: Add it.
* NEWS: Mention the fix.

NEWS

@@ -11,6 +11,9 @@ New in spot 1.2.3a (not yet released)
   * Bug fixes:
 
     - Change the Python bindings to make them compatible with Swig 3.0.
+    - "ltl2tgta --ta" could crash in certain conditions due to the
+      introduction of a simulation-based reduction after
+      degeneralization.
 
 New in spot 1.2.3 (2014-02-11)
 

src/taalgos/tgba2ta.cc

 // -*- coding utf-8 -*-
-// Copyright (C) 2010, 2011, 2012, 2013 Laboratoire de Recherche et
-// Développement de l'Epita (LRDE).
+// Copyright (C) 2010, 2011, 2012, 2013, 2014 Laboratoire de Recherche
+// et Développement de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
 //
@@ -431,35 +431,31 @@ namespace spot
 
       std::stack<state_ta_explicit*> todo;
       const tgba* tgba_ = ta->get_tgba();
-      const sba* sba_ = down_cast<const sba*>(tgba_);
-      assert(!degeneralized || sba_);
 
       // build Initial states set:
       state* tgba_init_state = tgba_->get_init_state();
 
       bdd tgba_condition = tgba_->support_conditions(tgba_init_state);
 
+      bool is_acc = false;
+      if (degeneralized)
+	{
+	  tgba_succ_iterator* it = tgba_->succ_iter(tgba_init_state);
+	  it->first();
+	  if (!it->done())
+	    is_acc = it->current_acceptance_conditions() != bddfalse;
+	  delete it;
+	}
+
       bdd satone_tgba_condition;
       while ((satone_tgba_condition = bdd_satoneset(tgba_condition,
 						    atomic_propositions_set_,
 						    bddtrue)) != bddfalse)
 	{
 	  tgba_condition -= satone_tgba_condition;
-	  state_ta_explicit* init_state;
-	  if (degeneralized)
-	    {
-	      init_state = new
-		state_ta_explicit(tgba_init_state->clone(),
-				  satone_tgba_condition, true,
-				  sba_->state_is_accepting(tgba_init_state));
-	    }
-	  else
-	    {
-	      init_state = new
-		state_ta_explicit(tgba_init_state->clone(),
-				  satone_tgba_condition, true, false);
-	    }
-
+	  state_ta_explicit* init_state = new
+	    state_ta_explicit(tgba_init_state->clone(),
+			      satone_tgba_condition, true, is_acc);
 	  state_ta_explicit* s = ta->add_state(init_state);
 	  assert(s == init_state);
 	  ta->add_to_initial_states_set(s);
@@ -492,6 +488,17 @@ namespace spot
 
 		  bdd all_props = bddtrue;
 		  bdd dest_condition;
+
+		  bool is_acc = false;
+		  if (degeneralized)
+		  {
+		    tgba_succ_iterator* it = tgba_->succ_iter(tgba_state);
+		    it->first();
+		    if (!it->done())
+		      is_acc = it->current_acceptance_conditions() != bddfalse;
+		    delete it;
+		  }
+
 		  if (satone_tgba_condition == source->get_tgba_condition())
 		    while ((dest_condition =
 			    bdd_satoneset(all_props,
@@ -499,21 +506,9 @@ namespace spot
 			   != bddfalse)
 		      {
 			all_props -= dest_condition;
-			state_ta_explicit* new_dest;
-			if (degeneralized)
-			  {
-			    new_dest = new state_ta_explicit
-			      (tgba_state->clone(),
-			       dest_condition,
-			       false,
-			       sba_->state_is_accepting(tgba_state));
-			  }
-			else
-			  {
-			    new_dest = new state_ta_explicit
-			      (tgba_state->clone(),
-			       dest_condition, false, false);
-			  }
+			state_ta_explicit* new_dest =
+			  new state_ta_explicit(tgba_state->clone(),
+						dest_condition, false, is_acc);
 			state_ta_explicit* dest = ta->add_state(new_dest);
 
 			if (dest != new_dest)

src/tgbatest/Makefile.am

@@ -96,6 +96,7 @@ TESTS = \
   ltl2neverclaim.test \
   ltl2neverclaim-lbtt.test \
   ltl2ta.test \
+  ltl2ta2.test \
   ltlprod.test \
   bddprod.test \
   explprod.test \

src/tgbatest/ltl2ta2.test

+#!/bin/sh
+# Copyright (C) 2014 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
+
+# This used to trigger an assert because of BA simulation not
+# returning an instance of spot::sba.
+run 0 ../../bin/ltl2tgta --ta 'G(F(a U b) U (c M d))'