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.

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;
   }
 

src/google/protobuf/compiler/parser.cc

@@ -1373,7 +1373,7 @@ bool Parser::ParseOption(Message* options,
           value_location.AddPath(
               UninterpretedOption::kNegativeIntValueFieldNumber);
           uninterpreted_option->set_negative_int_value(
-              -static_cast<int64>(value));
+              static_cast<int64>(-value));
         } else {
           value_location.AddPath(
               UninterpretedOption::kPositiveIntValueFieldNumber);

src/google/protobuf/io/tokenizer_unittest.cc

@@ -341,7 +341,7 @@ inline std::ostream& operator<<(std::ostream& out,
 MultiTokenCase kMultiTokenCases[] = {
   // Test empty input.
   { "", {
-    { Tokenizer::TYPE_END       , ""     , 0,  0 },
+    { Tokenizer::TYPE_END       , ""     , 0,  0,  0 },
   }},
 
   // Test all token types at the same time.

src/google/protobuf/message.h

@@ -753,7 +753,7 @@ class LIBPROTOBUF_EXPORT Reflection {
   // TODO(tmarek): Make virtual after all subclasses have been
   // updated.
   virtual void AddAllocatedMessage(Message* /* message */,
-                                   const FieldDescriptor* /*field */,
+                                   const FieldDescriptor* /* field */,
                                    Message* /* new_entry */) const {}
 
 
@@ -961,7 +961,7 @@ class LIBPROTOBUF_EXPORT Reflection {
   // TODO(jieluo) - make the map APIs pure virtual after updating
   // all the subclasses.
   // Returns true if key is in map. Returns false if key is not in map field.
-  virtual bool ContainsMapKey(const Message& /* message*/,
+  virtual bool ContainsMapKey(const Message& /* message */,
                               const FieldDescriptor* /* field */,
                               const MapKey& /* key */) const {
     return false;
@@ -979,7 +979,7 @@ class LIBPROTOBUF_EXPORT Reflection {
 
   // Delete and returns true if key is in the map field. Returns false
   // otherwise.
-  virtual bool DeleteMapValue(Message* /* mesage */,
+  virtual bool DeleteMapValue(Message* /* message */,
                               const FieldDescriptor* /* field */,
                               const MapKey& /* key */) const {
     return false;

src/google/protobuf/stubs/port.h

@@ -252,9 +252,15 @@ static const uint64 kuint64max = GOOGLE_ULONGLONG(0xFFFFFFFFFFFFFFFF);
 #define GOOGLE_GUARDED_BY(x)
 #define GOOGLE_ATTRIBUTE_COLD
 
+#ifdef GOOGLE_PROTOBUF_DONT_USE_UNALIGNED
+# define GOOGLE_PROTOBUF_USE_UNALIGNED 0
+#else
 // x86 and x86-64 can perform unaligned loads/stores directly.
-#if defined(_M_X64) || defined(__x86_64__) || \
+# define GOOGLE_PROTOBUF_USE_UNALIGNED defined(_M_X64) || \
-    defined(_M_IX86) || defined(__i386__)
+     defined(__x86_64__) || defined(_M_IX86) || defined(__i386__)
+#endif
+
+#if GOOGLE_PROTOBUF_USE_UNALIGNED
 
 #define GOOGLE_UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p))
 #define GOOGLE_UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p))

src/google/protobuf/util/message_differencer.h

@@ -241,18 +241,18 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
     // mutually exclusive. If a field has been both moved and modified, then
     // only ReportModified will be called.
     virtual void ReportMoved(
-        const Message& message1,
+        const Message& /* message1 */,
-        const Message& message2,
+        const Message& /* message2 */,
-        const std::vector<SpecificField>& field_path) { }
+        const std::vector<SpecificField>& /* field_path */) { }
 
     // Reports that two fields match. Useful for doing side-by-side diffs.
     // This function is mutually exclusive with ReportModified and ReportMoved.
     // Note that you must call set_report_matches(true) before calling Compare
     // to make use of this function.
     virtual void ReportMatched(
-        const Message& message1,
+        const Message& /* message1 */,
-        const Message& message2,
+        const Message& /* message2 */,
-        const std::vector<SpecificField>& field_path) { }
+        const std::vector<SpecificField>& /* field_path */) { }
 
     // Reports that two fields would have been compared, but the
     // comparison has been skipped because the field was marked as
@@ -274,16 +274,16 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
     // the fields are equal or not (perhaps with a second call to
     // Compare()), if it cares.
     virtual void ReportIgnored(
-        const Message& message1,
+        const Message& /* message1 */,
-        const Message& message2,
+        const Message& /* message2 */,
-        const std::vector<SpecificField>& field_path) { }
+        const std::vector<SpecificField>& /* field_path */) { }
 
     // Report that an unknown field is ignored. (see comment above).
     // Note this is a different function since the last SpecificField in field
     // path has a null field.  This could break existing Reporter.
     virtual void ReportUnknownFieldIgnored(
-        const Message& message1, const Message& message2,
+        const Message& /* message1 */, const Message& /* message2 */,
-        const std::vector<SpecificField>& field_path) {}
+        const std::vector<SpecificField>& /* field_path */) {}
 
    private:
     GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Reporter);
@@ -297,9 +297,9 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
     virtual ~MapKeyComparator();
 
     virtual bool IsMatch(
-        const Message& message1,
+        const Message& /* message1 */,
-        const Message& message2,
+        const Message& /* message2 */,
-        const std::vector<SpecificField>& parent_fields) const {
+        const std::vector<SpecificField>& /* parent_fields */) const {
       GOOGLE_CHECK(false) << "IsMatch() is not implemented.";
       return false;
     }
@@ -321,18 +321,18 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
 
     // Returns true if the field should be ignored.
     virtual bool IsIgnored(
-        const Message& message1,
+        const Message& /* message1 */,
-        const Message& message2,
+        const Message& /* message2 */,
-        const FieldDescriptor* field,
+        const FieldDescriptor* /* field */,
-        const std::vector<SpecificField>& parent_fields) = 0;
+        const std::vector<SpecificField>& /* parent_fields */) = 0;
 
     // Returns true if the unknown field should be ignored.
     // Note: This will be called for unknown fields as well in which case
     //       field.field will be null.
     virtual bool IsUnknownFieldIgnored(
-        const Message& message1, const Message& message2,
+        const Message& /* message1 */, const Message& /* message2 */,
-        const SpecificField& field,
+        const SpecificField& /* field */,
-        const std::vector<SpecificField>& parent_fields) {
+        const std::vector<SpecificField>& /* parent_fields */) {
       return false;
     }
   };

src/google/protobuf/wire_format_lite.h

@@ -197,7 +197,7 @@ class LIBPROTOBUF_EXPORT WireFormatLite {
 // type-safe, though, so prefer it if possible.
 #define GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(FIELD_NUMBER, TYPE)                  \
   static_cast<uint32>(                                                   \
-    ((FIELD_NUMBER) << ::google::protobuf::internal::WireFormatLite::kTagTypeBits) \
+    (static_cast<uint32>(FIELD_NUMBER) << ::google::protobuf::internal::WireFormatLite::kTagTypeBits) \
       | (TYPE))
 
   // These are the tags for the old MessageSet format, which was defined as: