Warn on non-virtual destructor if class has virtual functions

Makefile

@@ -352,6 +352,7 @@ CXXFLAGS += -std=c++11
 ifeq ($(SYSTEM),Darwin)
 CXXFLAGS += -stdlib=libc++
 endif
+CXXFLAGS += -Wnon-virtual-dtor
 CPPFLAGS += -g -Wall -Wextra -Werror -Wno-long-long -Wno-unused-parameter -DOSATOMIC_USE_INLINED=1 -Wno-deprecated-declarations -Ithird_party/nanopb -DPB_FIELD_32BIT
 COREFLAGS += -fno-rtti -fno-exceptions
 LDFLAGS += -g

build.yaml

@@ -5860,6 +5860,7 @@ defaults:
     COREFLAGS: -fno-rtti -fno-exceptions
     CPPFLAGS: -g -Wall -Wextra -Werror -Wno-long-long -Wno-unused-parameter -DOSATOMIC_USE_INLINED=1
       -Wno-deprecated-declarations -Ithird_party/nanopb -DPB_FIELD_32BIT
+    CXXFLAGS: -Wnon-virtual-dtor
     LDFLAGS: -g
   zlib:
     CFLAGS: -Wno-sign-conversion -Wno-conversion -Wno-unused-value -Wno-implicit-function-declaration

test/cpp/microbenchmarks/fullstack_fixtures.h

@@ -48,6 +48,7 @@ namespace testing {
 
 class FixtureConfiguration {
  public:
+  virtual ~FixtureConfiguration() {}
   virtual void ApplyCommonChannelArguments(ChannelArguments* c) const {
     c->SetInt(GRPC_ARG_MAX_RECEIVE_MESSAGE_LENGTH, INT_MAX);
     c->SetInt(GRPC_ARG_MAX_SEND_MESSAGE_LENGTH, INT_MAX);

test/cpp/microbenchmarks/helpers.h

@@ -63,6 +63,7 @@ extern gpr_atm gpr_now_call_count;
 class TrackCounters {
  public:
   TrackCounters() { grpc_stats_collect(&stats_begin_); }
+  virtual ~TrackCounters() {}
   virtual void Finish(benchmark::State& state);
   virtual void AddLabel(const grpc::string& label);
   virtual void AddToLabel(std::ostream& out, benchmark::State& state);