Default value of object parameterized with a RootRef generates incorrect C

[deech]

What happened?

The following code:

type
  Either[A,B] = object
    case kind:bool
    of false:
      b: B
    of true:
      a: A

  O = object of RootRef

proc oToEither(o:O):Either[O,void] =
  Either[O,void](kind:true,a: o)

discard oToEither(O())

fails to compile with:

/home/deech/.cache/nim/test_d/@mtest.nim.c:73:107: error: ‘union <anonymous>’ has no member named ‘_kind_1’; did you mean ‘_kind_2’?
   73 | static NIM_CONST tyObject_Either__D9a6Bf9aw0xiqmc0h0TIPoaw TM__ipcYmBC9bj9a1BW35ABoB1Kw_2 = {NIM_FALSE, {._kind_1 = {}}}
      |                                                                                                           ^~~~~~~
      |                                                                                                           _kind_2

Seems the default value of the Either tries to use a struct parameter that doesn't exist.

Nim Version

Nim Compiler Version 1.7.3 [Linux: amd64]
Compiled at 2022-10-29
Copyright (c) 2006-2022 by Andreas Rumpf

git hash: 534c97edc54ffb6d55baa5084f8c426a451c9244
active boot switches: -d:release

Current Standard Output Logs

No response

Expected Standard Output Logs

No response

Possible Solution

No response

Additional Information

No response

[deech]

git bisect shows the problem is in this commit

[ringabout]

I don't think so. It seems to be a pre-existing problem. It works with refc, not with ARC/ORC. I'm investigating it.

[arnetheduck]

worked around with status-im/nim-stew#150