ltl: use "final" and "override" in the AST classes

* src/ltlast/atomic_prop.hh, src/ltlast/binop.hh, src/ltlast/bunop.hh,
src/ltlast/constant.hh, src/ltlast/unop.hh: Here.
* src/misc/common.hh: Disable final for swig3.0.

src/ltlast/atomic_prop.hh

@@ -38,7 +38,7 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief Atomic propositions.
-    class SPOT_API atomic_prop : public formula
+    class SPOT_API atomic_prop final : public formula
     {
     public:
       /// Build an atomic proposition with name \a name in
@@ -46,7 +46,7 @@ namespace spot
       static const atomic_prop*
       instance(const std::string& name, environment& env);
 
-      virtual void accept(visitor& visitor) const;
+      virtual void accept(visitor& visitor) const override;
 
       /// Get the name of the atomic proposition.
       const std::string& name() const
@@ -61,7 +61,7 @@ namespace spot
       }
 
       /// Return a canonic representation of the atomic proposition
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Number of instantiated atomic propositions.  For debugging.
       static unsigned instance_count();

src/ltlast/binop.hh

@@ -40,7 +40,7 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief Binary operator.
-    class SPOT_API binop : public formula
+    class SPOT_API binop final: public formula
     {
     public:
       /// Different kinds of binary opertaors
@@ -110,7 +110,7 @@ namespace spot
 				     const formula* first,
 				     const formula* second);
 
-      virtual void accept(visitor& v) const;
+      virtual void accept(visitor& v) const override;
 
       /// Get the first operand.
       const formula* first() const
@@ -134,7 +134,7 @@ namespace spot
       const char* op_name() const;
 
       /// Return a canonic representation of the atomic proposition
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Number of instantiated binary operators.  For debugging.
       static unsigned instance_count();

src/ltlast/bunop.hh

@@ -35,7 +35,7 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief Bounded unary operator.
-    class SPOT_API bunop : public formula
+    class SPOT_API bunop final : public formula
     {
     public:
       enum type { Star };
@@ -85,7 +85,7 @@ namespace spot
 					unsigned min = 0,
 					unsigned max = unbounded);
 
-      virtual void accept(visitor& v) const;
+      virtual void accept(visitor& v) const override;
 
       /// Get the sole operand of this operator.
       const formula* child() const
@@ -120,7 +120,7 @@ namespace spot
       const char* op_name() const;
 
       /// Return a canonic representation of operation.
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Number of instantiated unary operators.  For debugging.
       static unsigned instance_count();

src/ltlast/constant.hh

@@ -32,11 +32,11 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief A constant (True or False)
-    class SPOT_API constant : public formula
+    class SPOT_API constant final : public formula
     {
     public:
       enum type { False, True, EmptyWord };
-      virtual void accept(visitor& v) const;
+      virtual void accept(visitor& v) const override;
 
       /// Return the value of the constant.
       type val() const
@@ -47,7 +47,7 @@ namespace spot
       /// Return the value of the constant as a string.
       const char* val_name() const;
 
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Get the sole instance of spot::ltl::constant::constant(True).
       static constant* true_instance() { return &true_instance_; }

src/ltlast/unop.hh

@@ -36,7 +36,7 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief Unary operators.
-    class SPOT_API unop : public formula
+    class SPOT_API unop final : public formula
     {
     public:
       enum type {
@@ -87,7 +87,7 @@ namespace spot
       /// handle this one as well.
       static const formula* instance(type op, const formula* child);
 
-      virtual void accept(visitor& v) const;
+      virtual void accept(visitor& v) const override;
 
       /// Get the sole operand of this operator.
       const formula* child() const
@@ -105,7 +105,7 @@ namespace spot
       const char* op_name() const;
 
       /// Return a canonic representation of the atomic proposition
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Number of instantiated unary operators.  For debugging.
       static unsigned instance_count();

src/misc/common.hh

@@ -78,8 +78,11 @@
 
 // Swig 2.0 does not understand '= delete'.  This already
 // works with the development version of Swig 3.
+// Swig 3.0.2 still does not understand 'final' when used
+// at class definition.
 #ifdef SWIG
   #define SPOT_DELETED
+  #define final
 #else
   #define SPOT_DELETED = delete
 #endif