Use = default for virtual constructors.

src/util/cmd_context_types.h

@@ -87,7 +87,7 @@ protected:
     int    m_pos;
 public:
     cmd(char const * n):m_name(n), m_line(0), m_pos(0) {}
-    virtual ~cmd() {}
+    virtual ~cmd() = default;
     virtual void reset(cmd_context & ctx) {}
     virtual void finalize(cmd_context & ctx) {}
     virtual symbol get_name() const { return m_name; }

src/util/event_handler.h

@@ -31,7 +31,7 @@ protected:
     event_handler_caller_t m_caller_id;
 public:
     event_handler(): m_caller_id(UNSET_EH_CALLER) {}
-    virtual ~event_handler() {}
+    virtual ~event_handler() = default;
     virtual void operator()(event_handler_caller_t caller_id) = 0;
     event_handler_caller_t caller_id() const { return m_caller_id; }
 };

src/util/trail.h

@@ -26,7 +26,7 @@ Revision History:
 
 class trail {
 public:
-    virtual ~trail() {}
+    virtual ~trail() = default;
     virtual void undo() = 0;
 };
 

src/util/z3_exception.h

@@ -22,7 +22,7 @@ Notes:
 
 class z3_exception {
 public:
-    virtual ~z3_exception() {}
+    virtual ~z3_exception() = default;
     virtual char const * msg() const = 0;
     virtual unsigned error_code() const;
     bool has_error_code() const;