Removing undefined behavior and compiler warnings (#1315)

* Comment out unused arguments.

These last few are all that's needed to compile with -Wunused-arguments.

* Fix missing struct field initializer.

With this fix, everything compiles with -Wmissing-field-initializers.

* Add support for disabling unaligned memory accesses on x86 too.

ubsan doesn't like these because they are technically undefined
behavior, so -DGOOGLE_PROTOBUF_DONT_USE_UNALIGNED will disable them easily.

* Avoid undefined integer overflow.

ubsan catches all of these.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/google/protobuf/arena.h b/src/google/protobuf/arena.h
index b6a375ac..0ffc6004 100644
--- a/src/google/protobuf/arena.h
+++ b/src/google/protobuf/arena.h
@@ -829,13 +829,13 @@ class LIBPROTOBUF_EXPORT Arena {
   }
   template <typename T>
   static void CreateInArenaStorageInternal(
-      T* ptr, Arena* arena, google::protobuf::internal::false_type) {
+      T* ptr, Arena* /* arena */, google::protobuf::internal::false_type) {
     new (ptr) T();
   }
 
   template <typename T>
   static void RegisterDestructorInternal(
-      T* ptr, Arena* arena, google::protobuf::internal::true_type) {}
+      T* /* ptr */, Arena* /* arena */, google::protobuf::internal::true_type) {}
   template <typename T>
   static void RegisterDestructorInternal(
       T* ptr, Arena* arena, google::protobuf::internal::false_type) {
@@ -870,7 +870,7 @@ class LIBPROTOBUF_EXPORT Arena {
   }
 
   template<typename T> GOOGLE_ATTRIBUTE_ALWAYS_INLINE
-  static ::google::protobuf::Arena* GetArenaInternal(const T* value, ...) {
+  static ::google::protobuf::Arena* GetArenaInternal(const T* /* value */, ...) {
     return NULL;
   }