CompilerFeatureRequiredAttribute
Indicates that compiler support for a particular feature is required for the location where this attribute is applied.
            
                
The  FeatureName used for the ref structs C# feature.
            
The  FeatureName used for the required members C# feature.
            
The name of the compiler feature.
            
If true, the compiler can choose to allow access to the location where this attribute is applied if it does not understand  FeatureName.