8.6.1

• [Analyzer] Multiple restrictions for regular unions
  • Union records must be sealed (because of copy constructor)
  • Union class must be sealed or have private constructors
  • Derived type of a union must not be less accessible than the base union
  • Derived type of a union must not have unbound generic parameters
• Implicit conversion is not generated for regular unions if it contains required members.
• Special handling of types and members starting with underscores and numbers