tests/regression/issue_504/test.proto

syntax = "proto3";

import "nanopb.proto";

message MyMessage
{
    SubMessage submessage = 1 [(nanopb).proto3_singular_msgs = true];
}

message SubMessage
{
    string somestring = 1 [(nanopb).type = FT_POINTER];
    SubMessage2 submsg2 = 2 [(nanopb).type = FT_POINTER];
}

message SubMessage2
{
    uint32 foo = 1;
}