internal error: not part of closure object type

[HJarausch]

I am trying the new recursive closure iterators.
A simple example works just fine.
But a larger one fails with
internal error: not part of closure object type

Unfortunately trying to come up with a smaller example source file (just the iterator is reference in the error message)
doesn't show the error.

So, I have to attach the full file with more than 2700 lines.

The error message is

Sudoku.nim(592, 18) Error: internal error: not part of closure object type

Nim Compiler Version 1.7.1 [Linux: amd64]
Compiled at 2022-07-07
git hash: 430a179

[HJarausch]

Sudoku_D.nim.gz
I have reduced the failing example.
Now, commenting only two lines of code make the compiler error vanish.
Nim Compiler Version 1.7.3 [Linux: amd64]
Compiled at 2022-11-12
git hash: 852cf59
active boot switches: -d:release

[bung87]

the problem is Loop_next call itsself.

[HJarausch]

Why is this a problem? Due to a recent patch, closure iterators are recursive.
I have tried simpler examples which all work just fine.
Thanks,
Helmut

[bung87]

maybe it's just a unhandled case , when I commented the error reporting it compiles and runs but get IndexError, didn't looking deeply into your code. could this exmaple be minimal, I haven't writen a resursive iterator myself.

[HJarausch]

I have reduced the size of the code to less than 50 lines.
The error still occurs with
Nim Compiler Version 1.9.5 [Linux: amd64]
Compiled at 2023-07-04
Copyright (c) 2006-2023 by Andreas Rumpf

git hash: 31ba104
BUG3.nim.txt

[Araq]

From bug3.nim.txt:

#!/usr/bin/env nimr
import std/[sets, tables, sequtils]

type
  i8 = int8
  seq8 = seq[int8]
  Cell    = seq8
  NODE    = tuple[d_in:int8,Strong:bool,link:Cell]
  PATH    = seq[NODE]

var
  R_Cells : int = -1
  max_level : int

var
  Seen:HashSet[NODE]
  path:PATH

iterator Loop_next(strong_link:bool, d_in:int8, node:Cell, head:int8, 
              Seen:var HashSet[NODE], path: var PATH, level:int ) : PATH {.closure.} = 

  if level > max_level :
    return
  let GNode= len(node) > 1   # without this line, the code compiles
  
  var
    rt, ct, st : seq8
    column_type : bool

#[ with this code commented out the compiler error does not occurs ]#
    
  st= filter(st, proc(x:int8) : bool = x notin node)
  if column_type :
    rt= @[]
    ct= filter(ct, proc(x:int8) : bool = x notin node)
  else :  # row type
    rt= filter(rt, proc(x:int8) : bool = x notin node)
    ct= @[]

#[]#
iterator Nice_Loop( ) : PATH {.closure.} =
  for cell in 0i8..80i8 :
    let head= cell

    for pt in  Loop_next(true,0.i8,@[cell], head,Seen,path,0) :
      yield pt

for P in  Nice_Loop() :
  continue

[dxxb]

As far as I can tell this has been fixed by #24316. Thank you @yglukhov.