chunks: declare DiscoverVersion destructor virtual

The concrete subclasses are deleted polymorphically
through a unique_ptr<DiscoverVersion>.

Also add -Wnon-virtual-dtor to the default CXXFLAGS
to prevent this from happening in the future.

Change-Id: If00a99566a54c7af4cd27df6fe68dcdef4cb4e82

.waf-tools/default-compiler-flags.py

@@ -132,6 +132,7 @@ class GccBasicFlags(CompilerFlags):
                               '-Wall',
                               '-Wextra',
                               '-Werror',
+                              '-Wnon-virtual-dtor',
                               '-Wno-error=deprecated-declarations', # Bug #3795
                               '-Wno-error=maybe-uninitialized', # Bug #1615
                               '-Wno-unused-parameter',
@@ -146,6 +147,7 @@ class GccBasicFlags(CompilerFlags):
                               '-pedantic',
                               '-Wall',
                               '-Wextra',
+                              '-Wnon-virtual-dtor',
                               '-Wno-unused-parameter',
                               ]
         flags['LINKFLAGS'] += ['-fuse-ld=gold', '-Wl,-O1']

tools/chunks/catchunks/discover-version.cpp

@@ -1,8 +1,8 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2016,  Regents of the University of California,
- *                      Colorado State University,
- *                      University Pierre & Marie Curie, Sorbonne University.
+/*
+ * Copyright (c) 2016-2017, Regents of the University of California,
+ *                          Colorado State University,
+ *                          University Pierre & Marie Curie, Sorbonne University.
  *
  * This file is part of ndn-tools (Named Data Networking Essential Tools).
  * See AUTHORS.md for complete list of ndn-tools authors and contributors.
@@ -38,9 +38,10 @@ DiscoverVersion::DiscoverVersion(const Name& prefix, Face& face, const Options&
 {
 }
 
+DiscoverVersion::~DiscoverVersion() = default;
+
 void
-DiscoverVersion::expressInterest(const Interest& interest, int maxRetriesNack,
-                                 int maxRetriesTimeout)
+DiscoverVersion::expressInterest(const Interest& interest, int maxRetriesNack, int maxRetriesTimeout)
 {
   fetcher = DataFetcher::fetch(m_face, interest, maxRetriesNack, maxRetriesTimeout,
                                bind(&DiscoverVersion::handleData, this, _1, _2),

tools/chunks/catchunks/discover-version.hpp

@@ -1,8 +1,8 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2016,  Regents of the University of California,
- *                      Colorado State University,
- *                      University Pierre & Marie Curie, Sorbonne University.
+/*
+ * Copyright (c) 2016-2017, Regents of the University of California,
+ *                          Colorado State University,
+ *                          University Pierre & Marie Curie, Sorbonne University.
  *
  * This file is part of ndn-tools (Named Data Networking Essential Tools).
  * See AUTHORS.md for complete list of ndn-tools authors and contributors.
@@ -64,6 +64,9 @@ public:
    */
   DiscoverVersion(const Name& prefix, Face& face, const Options& options);
 
+  virtual
+  ~DiscoverVersion();
+
   /**
    * @brief identify the latest Data version published.
    */