diff -r ecc2af326b5f -r 8e17fffa0a4b src/hotspot/share/services/diagnosticArgument.hpp
--- a/src/hotspot/share/services/diagnosticArgument.hpp	Fri Jun 15 16:53:58 2018 -0400
+++ b/src/hotspot/share/services/diagnosticArgument.hpp	Sat Jun 16 07:05:09 2018 +0200
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -62,40 +62,35 @@
 class GenDCmdArgument : public ResourceObj {
 protected:
   GenDCmdArgument* _next;
-  const char*      _name;
-  const char*      _description;
-  const char*      _type;
-  const char*      _default_string;
-  bool             _is_set;
-  bool             _is_mandatory;
+  const char* const _name;
+  const char* const _description;
+  const char* const _type;
+  const char* const _default_string;
+  bool              _is_set;
+  const bool        _is_mandatory;
   bool             _allow_multiple;
   GenDCmdArgument(const char* name, const char* description, const char* type,
-                  const char* default_string, bool mandatory) {
-    _name = name;
-    _description = description;
-    _type = type;
-    _default_string = default_string;
-    _is_mandatory = mandatory;
-    _is_set = false;
-    _allow_multiple = false;
-  };
+                  const char* default_string, bool mandatory)
+    : _next(NULL), _name(name), _description(description), _type(type),
+      _default_string(default_string), _is_set(false), _is_mandatory(mandatory),
+      _allow_multiple(false) {}
 public:
-  const char* name() { return _name; }
-  const char* description() { return _description; }
-  const char* type() { return _type; }
-  const char* default_string() { return _default_string; }
-  bool is_set() { return _is_set; }
-  void set_is_set(bool b) { _is_set = b; }
-  bool allow_multiple() { return _allow_multiple; }
-  bool is_mandatory() { return _is_mandatory; }
-  bool has_value() { return _is_set || _default_string != NULL; }
-  bool has_default() { return _default_string != NULL; }
+  const char* name() const        { return _name; }
+  const char* description() const { return _description; }
+  const char* type() const        { return _type; }
+  const char* default_string() const { return _default_string; }
+  bool is_set() const             { return _is_set; }
+  void set_is_set(bool b)         { _is_set = b; }
+  bool allow_multiple() const     { return _allow_multiple; }
+  bool is_mandatory() const       { return _is_mandatory; }
+  bool has_value() const          { return _is_set || _default_string != NULL; }
+  bool has_default() const        { return _default_string != NULL; }
   void read_value(const char* str, size_t len, TRAPS);
   virtual void parse_value(const char* str, size_t len, TRAPS) = 0;
   virtual void init_value(TRAPS) = 0;
   virtual void reset(TRAPS) = 0;
   virtual void cleanup() = 0;
-  virtual void value_as_str(char* buf, size_t len) = 0;
+  virtual void value_as_str(char* buf, size_t len) const = 0;
   void set_next(GenDCmdArgument* arg) {
     _next = arg;
   }
@@ -103,12 +98,12 @@
     return _next;
   }
 
-  void to_string(jlong l, char* buf, size_t len);
-  void to_string(bool b, char* buf, size_t len);
-  void to_string(char* c, char* buf, size_t len);
-  void to_string(NanoTimeArgument n, char* buf, size_t len);
-  void to_string(MemorySizeArgument f, char* buf, size_t len);
-  void to_string(StringArrayArgument* s, char* buf, size_t len);
+  void to_string(jlong l, char* buf, size_t len) const;
+  void to_string(bool b, char* buf, size_t len) const;
+  void to_string(char* c, char* buf, size_t len) const;
+  void to_string(NanoTimeArgument n, char* buf, size_t len) const;
+  void to_string(MemorySizeArgument f, char* buf, size_t len) const;
+  void to_string(StringArrayArgument* s, char* buf, size_t len) const;
 };
 
 template <class ArgType> class DCmdArgument: public GenDCmdArgument {
@@ -123,7 +118,7 @@
                GenDCmdArgument(name, description, type, defaultvalue, mandatory)
                { }
   ~DCmdArgument() { destroy_value(); }
-  ArgType value() { return _value;}
+  ArgType value() const { return _value;}
   void set_value(ArgType v) { _value = v; }
   void reset(TRAPS) {
     destroy_value();
@@ -136,7 +131,7 @@
   void parse_value(const char* str, size_t len, TRAPS);
   void init_value(TRAPS);
   void destroy_value();
-  void value_as_str(char *buf, size_t len) { return to_string(_value, buf, len);}
+  void value_as_str(char *buf, size_t len) const { to_string(_value, buf, len);}
 };
 
 #endif  /* SHARE_VM_SERVICES_DIAGNOSTICARGUMENT_HPP */