neverparse: Fix parsing of Modella's neverclaims.

Reported by František Blahoudek.

* src/neverparse/neverclaimparse.yy: Fix.
* src/tgbatest/neverclaimread.test: Test it.
* NEWS: Mention the fix.

NEWS

@@ -3,6 +3,7 @@ New in spot 1.2.4a (not yet released)
   * Bug fixes:
 
     - Fix simplification of bounded repetition in SERE formulas.
+    - Fix parsing of neverclaims produced by Modella.
 
 New in spot 1.2.4 (2014-05-15)
 

src/neverparse/neverclaimparse.yy

@@ -1,5 +1,5 @@
 /* -*- coding: utf-8 -*-
-** Copyright (C) 2010, 2011, 2012, 2013 Laboratoire de Recherche et
+** 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.
@@ -191,7 +191,7 @@ transitions:
     }
 
 
-formula: FORMULA | "false" { $$ = new std::string("0"); }
+formula: FORMULA | IDENT | "false" { $$ = new std::string("0"); }
 
 opt_dest:
   /* empty */

src/tgbatest/neverclaimread.test

@@ -1,7 +1,7 @@
 #!/bin/sh
 # -*- 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.
 #
@@ -172,6 +172,40 @@ EOF
 grep input: stderr >> stderrfilt
 diff stderrfilt expected
 
+
+# This output from MoDeLLa was not property parsed by Spot because of
+# the missing parentheses around p0.  Report from František Blahoudek.
+cat >input <<EOF
+never{
+T0_init:
+	if
+	:: true -> goto T1
+	:: p0 -> goto T2
+	fi;
+T1:
+	if
+	:: true -> goto T1
+	:: p0 -> goto accept_T3
+	fi;
+T2:
+	if
+	:: p0 -> goto accept_T3
+	fi;
+accept_T3:
+	if
+	:: p0 -> goto T2
+	fi;
+}
+EOF
+cat >expected<<EOF
+transitions: 6
+states: 4
+EOF
+
+run 0 ../ltl2tgba -ks -XN input > output
+diff output expected
+
+
 cat >formulae<<EOF
 a
 FG a