Support cyclically referenced fields

[clickingbuttons]

According to a Flatbuffers maintainer (and the reference C++ impl) cyclical referencing tables are possible.

This means for the object API this:

const Foo = struct {
    foo: ?Foo,
};

should change to this:

const Foo = struct {
    foo: ?*Foo,
};

and the init allocations should change too.

[archaistvolts]

It seems like the flatbuffers compiler does accept recursive tables:

// /tmp/tmp.fbs
table Monster {
  mana: short=150;
  m: Monster;
}

Using flatbufferz, the following results in /tmp/fbgen/Monster.fb.zig.

zig-out/bin/flatc-zig /tmp/tmp.fbs -o /tmp/fbgen

[clickingbuttons]

I'd call those nested. I currently handle nested fields fine.

My question is if in your example I build a monster where the m points to itself do existing flatbuffer tools work? My unpacking implementation will currently stack overflow.

Updated OP.

[clickingbuttons]

The builder needs to support cyclical references. For codegen it's also fairly hard to detect fields that can be cyclical. An alternative is to make every table field a reference, but that defeats a large point of the object API.

I think this feature should be behind a flag and implemented before 1.0.0.