proto3 map empty bytes

[awalterschulze]

Add this to proto3.proto in proto/proto3_proto

message MessageWithMappy {
  map<bool, bytes> byte_mapping = 3;
}

and run the Makefile in proto/proto3_proto

Then add this to size_test.go

{"map field with zero bytes", &proto3pb.MessageWithMappy{
        ByteMapping: map[bool][]byte{
            false: []byte{},
            true:  []byte{0x84, 0x78, 0x8e, 0x33, 0xcd, 0x12, 0x65, 0xa0, 0xd2, 0xca, 0xc4, 0xcd, 0x12, 0xe2, 0xcf, 0xf1, 0xbf, 0xfa, 0xf7, 0x5a, 0x3c, 0x6d, 0xdc, 0xcf, 0x9c, 0x92, 0x94, 0x3f, 0x4f, 0xb6, 0x31, 0x77, 0xe3, 0xda, 0x3f, 0x1b, 0x8e, 0x39, 0xe6, 0xa, 0x81, 0x61, 0xf0, 0xba, 0x74, 0x6},
        },
    }},

This gives the following failure

size_test.go:138: map field with zero bytes: Size(byte_mapping:<key:false value:"" > byte_mapping:<key:true value:"\204x\2163\315\022e\240\322\312\304\315\022\342\317\361\277\372\367Z<m\334\317\234\222\224?O\2661w\343\332?\033\2169\346\n\201a\360\272t\006" > ) = 56, want 7
size_test.go:139: map field with zero bytes: bytes: []byte{0x1a, 0x0, 0x0, 0x0, 0x0, 0x8, 0x0}

The error only happens with an empty byte slice.

This is probably a mistake in the way the map values try to reuse the setEncAndDec function with a combination of the proto3 syntax

case reflect.Uint8:
            p.enc = (*Buffer).enc_slice_byte
            p.dec = (*Buffer).dec_slice_byte
            p.size = size_slice_byte
            if p.proto3 {
                p.enc = (*Buffer).enc_proto3_slice_byte
                p.size = size_proto3_slice_byte
            }

Maybe this should be

case reflect.Uint8:
            p.enc = (*Buffer).enc_slice_byte
            p.dec = (*Buffer).dec_slice_byte
            p.size = size_slice_byte
            if p.proto3 && notamapvalue {
                p.enc = (*Buffer).enc_proto3_slice_byte
                p.size = size_proto3_slice_byte
            }

[awalterschulze]

This seems to work

case reflect.Uint8:
            p.enc = (*Buffer).enc_slice_byte
            p.dec = (*Buffer).dec_slice_byte
            p.size = size_slice_byte
            if p.proto3 && f != nil {
                p.enc = (*Buffer).enc_proto3_slice_byte
                p.size = size_proto3_slice_byte
            }