Non-flags enums should not be used in bitwise operations

enum}}s are usually used to identify distinct elements in a set of values. However {{enum}}s can be treated as bit fields and bitwise operations can be used on them to combine the values. This is a good way of specifying multiple elements of set with a single value. When {{enum}}s are used this way, it is a best practice to mark the {{enum with the FlagsAttribute.

Noncompliant Code Example

enum Permissions
{ 
  None = 0,
  Read = 1,   
  Write = 2, 
  Execute = 4 
}
// ...

var x = Permissions.Read | Permissions.Write;  // Noncompliant; enum is not marked with [Flags]

Compliant Solution

[Flags]
enum Permissions
{ 
  None = 0,
  Read = 1, 
  Write = 2, 
  Execute = 4
}
// ...

var x = Permissions.Read | Permissions.Write;