[PATCH] D125609: [ADT] Adopt the new casting infrastructure for PointerUnion

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0x59616e added a comment.

Thanks for feedback ;)

In D125609#3514018 <https://reviews.llvm.org/D125609#3514018>, @bzcheeseman wrote:

> In D125609#3514009 <https://reviews.llvm.org/D125609#3514009>, @0x59616e wrote:
>
>> Define `CastInfoPointerUnionImpl` as below :
>>
>>   template <typename... PTs> struct CastInfoPointerUnionImpl {
>>     using From = PointerUnion<PTs...>;
>>   
>>     template <typename To> static inline bool isPossible(From &F) {
>>      return  F.Val.getInt() == FirstIndexOfType<To, PTs...>::value;
>>     }
>>   
>>     template <typename To> static To doCast(From &F) {
>>       assert(isPossible<To>(F) && "cast to an incompatible type !");
>>       return PointerLikeTypeTraits<To>::getFromVoidPointer(F.Val.getPointer());
>>     }
>>   };
>>
>> and declared it as a friend of PointerUnion.
>
> Could you declare the CastInfo struct itself as a friend? something like `template<typename To, typename...PTs> friend struct CastInfo<To, PointerUnion<PTs...>>`? That way you don't need the impl struct so it cuts down on overall code. Truly asking here - I think it's doable but I may be wrong.

It seems that partial specialization struct can't be declared as a friend.


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https://reviews.llvm.org/D125609