Copy constructor for C++ Object API

[cdfh]

Flatbuffer objects in the C++ Object API cannot be copied if they include other tables as elements due to the use of std::unique_ptr to reference the other tables.

For example, the schema

table Bar {
...
}

table Foo {
  bars: [Bar];
}

compiles to

struct FooT : public flatbuffers::NativeTable {
  ...
  std::vector<flatbuffers::unique_ptr<BarT>> bars;  // resolves to std::unique_ptr
  ...
};

noting that std::unique_ptr disallows copying. Thus, I cannot copy instances of FooT without considerable code verbosity (e.g., packing and unpacking the FooT instance).

My understanding is that the Object API is designed to increase convenience in instances where non-copy constraints are relaxed, and so it seems a bug not to bless them with a copy constructor.

[aardappel]

I agree that generating an explicit copy contructor would make sense.. care to create a PR for that?

[github-actions]

This issue is stale because it has been open 6 months with no activity. Please comment or this will be closed in 14 days.

[cdfh]

Commenting to prevent the issue from automatically closing. Looks like a fix is imminent though still pending with #5988.

[jfroy]

Thanks. Sorry for the lack of updates, I've been busy. Will get to it...

[github-actions]

This issue is stale because it has been open 6 months with no activity. Please comment or this will be closed in 14 days.