Fix computation of support_conditions in tgba_wdba_comp_proxy.

* src/tgba/wdbacomp.cc
(tgba_wdba_comp_proxy::compute_support_conditions): Fix.
* src/tgbatest/wdba2.test: Test a formula that used to be wrongly
minimized if translated by LaCIM, because the product of a
tgbabddconcrete automaton with another automaton (done during
WDBA-minimization) use the support conditions to speed things up.

src/tgba/wdbacomp.cc

@@ -1,5 +1,6 @@
-// Copyright (C) 2011 Laboratoire de Recherche et Développement de
-// l'Epita.
+// -*- coding: utf-8 -*-
+// Copyright (C) 2011, 2012 Laboratoire de Recherche et Développement
+// de l'Epita.
 //
 // This file is part of Spot, a model checking library.
 //
@@ -248,18 +249,12 @@ namespace spot
 	return !the_acceptance_cond_;
       }
 
-  protected:
-    virtual bdd
-    compute_support_conditions(const state* ostate) const
+    protected:
+      virtual bdd
+      compute_support_conditions(const state*) const
       {
-	const state_wdba_comp_proxy* s =
-	  down_cast<const state_wdba_comp_proxy*>(ostate);
-	assert(s);
-	const state* rs = s->real_state();
-	if (rs)
-	  return a_->support_conditions(rs);
-	else
-	  return bddtrue;
+	// The automaton is complete, so we always support all variables.
+	return bddtrue;
       }
 
       virtual bdd compute_support_variables(const state* ostate) const

src/tgbatest/wdba2.test

@@ -1,4 +1,5 @@
 #!/bin/sh
+# -*- coding: utf-8 -*-
 # Copyright (C) 2012 Laboratoire de Recherche et Développement
 # de l'Epita (LRDE).
 #
@@ -36,3 +37,12 @@ run 0 ../ltl2tgba -Rm -kt 'Fa | XGd' > out2
 
 cmp out expected
 cmp out2 expected
+
+
+# This non-obligation formula used to be minimized by mistake when
+# translated with lacim.
+x=`../ltl2tgba -l -Rm 'F(Fa R (Gb & !a))' |
+   grep -v -- '->' |
+   sed -n 's/.*label="\(..*\)".*/\1/p' |
+   tr -d '0-9\n'`
+test -n "$x"