better fix for MSVC compilation issue

Summary:
This diff is a more complete fix for the problem addressed
by D19561643, in which private inheritance caused an incorrect
inaccessibility error for a type that was derived via an alternate
construction from a template param.

Reviewed By: lnicco

Differential Revision: D20718329

fbshipit-source-id: 778d246d07030f6abb9e08e127a98d48c736a7d7

folly/container/detail/F14Policy.h

@@ -76,7 +76,7 @@ struct ObjectHolder {
 };
 
 template <char Tag, typename T>
-struct ObjectHolder<Tag, T, true> : private T {
+struct ObjectHolder<Tag, T, true> : T {
   template <typename... Args>
   ObjectHolder(Args&&... args) : T{std::forward<Args>(args)...} {}
 
@@ -1044,15 +1044,15 @@ class VectorContainerPolicy : public BasePolicy<
       AllocOrVoid,
       uint32_t>;
   using Value = typename Super::Value;
-  using Alloc = Defaulted<AllocOrVoid, DefaultAlloc<Value>>;
+  using Alloc = typename Super::Alloc;
   using AllocTraits = typename Super::AllocTraits;
   using ByteAlloc = typename Super::ByteAlloc;
   using ByteAllocTraits = typename Super::ByteAllocTraits;
   using BytePtr = typename Super::BytePtr;
-  using Hasher = Defaulted<HasherOrVoid, DefaultHasher<Key>>;
+  using Hasher = typename Super::Hasher;
   using Item = typename Super::Item;
   using ItemIter = typename Super::ItemIter;
-  using KeyEqual = Defaulted<KeyEqualOrVoid, DefaultKeyEqual<Key>>;
+  using KeyEqual = typename Super::KeyEqual;
 
   using Super::kAllocIsAlwaysEqual;
 

folly/container/detail/F14Table.h

@@ -403,8 +403,7 @@ struct alignas(kRequiredVectorAlignment) F14Chunk {
             scale < (std::size_t{1} << kCapacityScaleBits),
         "");
     if (kCapacityScaleBits == 4) {
-      control_ =
-          static_cast<uint8_t>((control_ & ~0xf) | static_cast<uint8_t>(scale));
+      control_ = static_cast<uint8_t>((control_ & ~0xf) | scale);
     } else {
       uint16_t v = static_cast<uint16_t>(scale);
       std::memcpy(&tags_[12], &v, 2);