type Instr = ref object of RootObj
type OneOpInstr[T] = ref object of Instr
    op*: T

proc newOneOpInstr[T](op: T): ref OneOpInstr[T] =
    new(result)
    result.op = op

proc x(): ref Instr =
    result = newOneOpInstr(5)


$ nim c --parallelBuild:1 xx.nim
config/nim.cfg(53, 3) Hint: added path: '/home/dalar/.babel/pkgs/' [Path]
config/nim.cfg(54, 3) Hint: added path: '/home/dalar/.nimble/pkgs/' [Path]
Hint: used config file '/home/dalar/repos/Nim/config/nim.cfg' [Conf]
Hint: system [Processing]
Hint: xx [Processing]
xx.nim(10, 6) Hint: 'xx.x()' is declared but not used [XDeclaredButNotUsed]
gcc -c  -w  -I/home/dalar/repos/Nim/lib -o /home/dalar/repos/nimiona/nimcache/xx.o /home/dalar/repos/nimiona/nimcache/xx.c
/home/dalar/repos/nimiona/nimcache/xx.c: In function ‘x_90035’:
/home/dalar/repos/nimiona/nimcache/xx.c:123:16: error: request for member ‘Sup’ in something not a structure or union
  result = &LOC1->Sup;
                ^
Error: execution of an external program failed