Different enums, same value in protobuf

Question

I have protocol buffer definitions like this:

package com.asd;

enum AType {
    A1 = 0;
    A2 = 1;
    Unknown = 2;
}

enum BType {
    B1 = 0;
    B2 = 1;
    Unknown = 2;
}

While compiling, I am getting this error:

"Unknown" is already defined in "com.asd". Note that enum values use C++ scoping rules, meaning that enum values are siblings of their type, not children of it. Therefore, "Other" must be unique within "com.asd", not just within "BType".

Is there a workaround for this problem other than using different packages?

Answer 1

I believe there is no straightforward way of using the same enum value in the same package but there are two workarounds (link):

1. Use prefix:

    package com.asd;
   
    enum AType {
        AType_A1 = 0;
        AType_A2 = 1;
        AType_Unknown = 2;
    }
   
    enum BType {
        BType_B1 = 0;
        BType_B2 = 1;
        BType_Unknown = 2;
    }
   

2. Put the enums in different messages:

    message ATypeMessage{
        enum AType{
            A1 = 0;
            A2 = 1;
            Unknown = 2;
        }
    }
   
    message BTypeMessage{
        enum BType{
            B1 = 0;
            B2 = 1;
            Unknown = 2;   
        }
    }
   

Answer 2

I don't have enough reputation to post this as a comment, and my suggestion is a hack that might not even work. But have you tried to add the option allow_alias = true; in both enum and use the same value.

Ref: https://developers.google.com/protocol-buffers/docs/proto#enum