fix build

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/muz/spacer/spacer_itp_solver.h

@@ -110,9 +110,7 @@ public:
     void set_produce_models(bool f) override  { m_solver.set_produce_models(f);}
     void assert_expr_core(expr *t) override  { m_solver.assert_expr(t);}
     void assert_expr_core2(expr *t, expr *a) override   { NOT_IMPLEMENTED_YET();}
-    virtual void assert_lemma(expr* e) { NOT_IMPLEMENTED_YET(); }
-    virtual expr_ref lookahead(const expr_ref_vector &,const expr_ref_vector &) { return expr_ref(m.mk_true(), m); }
-    virtual expr_ref_vector cube(expr_ref_vector&, unsigned) { return expr_ref_vector(m); }
+    expr_ref_vector cube(expr_ref_vector&, unsigned) override { return expr_ref_vector(m); }
 
     void push() override;
     void pop(unsigned n) override;

src/muz/transforms/dl_mk_karr_invariants.cpp

@@ -152,7 +152,9 @@ namespace datalog {
             return mc;
         }
 
-        virtual void display(std::ostream& out) { out << "(add-invariant-model-converter)\n"; }
+        void display(std::ostream& out) override { 
+            out << "(add-invariant-model-converter)\n"; 
+        }
 
     private:
         void mk_body(matrix const& M, expr_ref& body) {

src/muz/transforms/dl_mk_quantifier_abstraction.cpp

@@ -53,9 +53,9 @@ namespace datalog {
             return alloc(qa_model_converter, m);
         }
 
-        virtual void display(std::ostream& out) { display_add(out, m); }
+        void display(std::ostream& out) override { display_add(out, m); }
 
-        virtual void get_units(obj_map<expr, bool>& units) { units.reset(); }        
+        void get_units(obj_map<expr, bool>& units) override { units.reset(); }        
 
         void insert(func_decl* old_p, func_decl* new_p, expr_ref_vector& sub, sort_ref_vector& sorts, svector<bool> const& bound) {
             m_old_funcs.push_back(old_p);

src/muz/transforms/dl_mk_scale.cpp

@@ -100,7 +100,7 @@ namespace datalog {
             return nullptr;
         }
 
-        virtual void display(std::ostream& out) { out << "(scale-model-converter)\n"; }
+        void display(std::ostream& out) override { out << "(scale-model-converter)\n"; }
 
     };