fix serialization being different on mac

On Mac, size_t is a distinct type from uint64_t, and some
types (in wallet cache as well as cold/hot wallet transfer
data) use pairs/containers with size_t as fields. Mac would
save those as full size, while other platforms would save
them as varints. Might apply to other platforms where the
types are distinct.

There's a nasty hack for backward compatibility, which can
go after a couple forks.

4 files changed, 40 insertions, 13 deletions

diff --git a/src/serialization/binary_archive.h b/src/serialization/binary_archive.h
index 80104c8f7..49ca8aa57 100644
--- a/src/serialization/binary_archive.h
+++ b/src/serialization/binary_archive.h
@@ -98,7 +98,7 @@ template <>
 struct binary_archive<false> : public binary_archive_base<std::istream, false>
 {
 
-  explicit binary_archive(stream_type &s) : base_type(s) {
+  explicit binary_archive(stream_type &s) : base_type(s), varint_bug_backward_compatibility_(false) {
     stream_type::pos_type pos = stream_.tellg();
     stream_.seekg(0, std::ios_base::end);
     eof_pos_ = stream_.tellg();
@@ -173,8 +173,13 @@ struct binary_archive<false> : public binary_archive_base<std::istream, false>
     assert(stream_.tellg() <= eof_pos_);
     return eof_pos_ - stream_.tellg();
   }
+
+  void enable_varint_bug_backward_compatibility() { varint_bug_backward_compatibility_ = true; }
+  bool varint_bug_backward_compatibility_enabled() const { return varint_bug_backward_compatibility_; }
+
 protected:
   std::streamoff eof_pos_;
+  bool varint_bug_backward_compatibility_;
 };
 
 template <>
@@ -227,6 +232,8 @@ struct binary_archive<true> : public binary_archive_base<std::ostream, true>
   void write_variant_tag(variant_tag_type t) {
     serialize_int(t);
   }
+
+  bool varint_bug_backward_compatibility_enabled() const { return false; }
 };
 
 POP_WARNINGS
diff --git a/src/serialization/container.h b/src/serialization/container.h
index d5e75bb4f..a4997c8ae 100644
--- a/src/serialization/container.h
+++ b/src/serialization/container.h
@@ -32,22 +32,27 @@ namespace serialization
 {
   namespace detail
   {
-    template <typename Archive, class T>
-    bool serialize_container_element(Archive& ar, T& e)
+    template<typename T>
+    inline constexpr bool use_container_varint() noexcept
     {
-      return ::do_serialize(ar, e);
+      return std::is_integral<T>::value && std::is_unsigned<T>::value && sizeof(T) > 1;
     }
 
-    template <typename Archive>
-    bool serialize_container_element(Archive& ar, uint32_t& e)
+    template <typename Archive, class T>
+    typename std::enable_if<!use_container_varint<T>(), bool>::type
+    serialize_container_element(Archive& ar, T& e)
     {
-      ar.serialize_varint(e);
-      return true;
+      return ::do_serialize(ar, e);
     }
 
-    template <typename Archive>
-    bool serialize_container_element(Archive& ar, uint64_t& e)
+    template<typename Archive, typename T>
+    typename std::enable_if<use_container_varint<T>(), bool>::type
+    serialize_container_element(Archive& ar, T& e)
     {
+      static constexpr const bool previously_varint = std::is_same<uint64_t, T>() || std::is_same<uint32_t, T>();
+
+      if (!previously_varint && ar.varint_bug_backward_compatibility_enabled() && !typename Archive::is_saving())
+        return ::do_serialize(ar, e);
       ar.serialize_varint(e);
       return true;
     }
diff --git a/src/serialization/json_archive.h b/src/serialization/json_archive.h
index 50dd5bbd0..3f98b5101 100644
--- a/src/serialization/json_archive.h
+++ b/src/serialization/json_archive.h
@@ -84,6 +84,8 @@ struct json_archive_base
   void end_variant() { end_object(); }
   Stream &stream() { return stream_; }
 
+  bool varint_bug_backward_compatibility_enabled() const { return false; }
+
 protected:
   void make_indent()
   {
diff --git a/src/serialization/pair.h b/src/serialization/pair.h
index 18280d837..44aafa04d 100644
--- a/src/serialization/pair.h
+++ b/src/serialization/pair.h
@@ -30,21 +30,34 @@
 
 #pragma once
 #include <memory>
+#include <boost/type_traits/make_unsigned.hpp>
 #include "serialization.h"
 
 namespace serialization
 {
   namespace detail
   {
+    template<typename T>
+    inline constexpr bool use_pair_varint() noexcept
+    {
+      return std::is_integral<T>::value && std::is_unsigned<T>::value && sizeof(T) > 1;
+    }
+
     template <typename Archive, class T>
-    bool serialize_pair_element(Archive& ar, T& e)
+    typename std::enable_if<!use_pair_varint<T>(), bool>::type
+    serialize_pair_element(Archive& ar, T& e)
     {
       return ::do_serialize(ar, e);
     }
 
-    template <typename Archive>
-    bool serialize_pair_element(Archive& ar, uint64_t& e)
+    template<typename Archive, typename T>
+    typename std::enable_if<use_pair_varint<T>(), bool>::type
+    serialize_pair_element(Archive& ar, T& e)
     {
+      static constexpr const bool previously_varint = std::is_same<uint64_t, T>();
+
+      if (!previously_varint && ar.varint_bug_backward_compatibility_enabled() && !typename Archive::is_saving())
+        return ::do_serialize(ar, e);
       ar.serialize_varint(e);
       return true;
     }