UE5.4.0-preview-1: C2248 'TMemoryWriterBase<TSizedDefaultAllocator<32>>::IndexSize': cannot access private member declared in class 'TMemoryWriterBase<TSizedDefaultAllocator<32>>'

[kiruru002]

Default member initializers for bit-fields requires at least '/std:c++20'

This is the only solution that worked for me.

For me, who uses UE5.5, the fix didn’t work, but I got a hint from another thread I was looking at recently, and

CppStandard = CppStandardVersion.Cpp20;

I was able to successfully build by putting it in build.cs instead.