C codegen error (error: ‘colonenv_’ undeclared) when using same iterator twice

[arkanoid87]

C codegen error (error: ‘colonenv_’ undeclared) when using same iterator twice

happens both in stable & devel

Example

comment last line to compile successfully

https://play.nim-lang.org/#ix=3wLt

import std/[
  sequtils
]

type
  VisitOrder = enum
    voLeaf,
    voRoot
  MyNode = object
    name: string
    children: seq[MyNode]
    visited: bool


iterator walk(node: MyNode, visitOrder = voLeaf): MyNode =
  ## Walk tree, level order, direction by visitOrder parameter

  var resultSeq = newSeq[MyNode]()

  func callback(node: MyNode) =
    resultSeq.add node

  func visit(node: var MyNode) =
    callback(node)
    node.visited = true

  func resetVisited(node: var MyNode) =
    node.visited = false
    for c in node.children.mitems:
      c.resetVisited

  func allVisited(node: MyNode): bool =
    result = node.visited
    for c in node.children:
      result = result and c.allVisited

  func leafOrder(node: var MyNode) =
    if not node.visited and node.children.allIt(it.visited): # is leaf
      node.visit
    else:
      for c in node.children.mitems:
        c.leafOrder

  func rootOrder(node: var MyNode) =
    func aux(node: var MyNode) =
      for c in node.children.mitems:
        c.visit
      for c in node.children.mitems:
        c.aux
    node.visit
    node.aux

  var mutableMyNode = node
  mutableMyNode.resetVisited
  while not mutableMyNode.allVisited:
    case visitOrder
    of voLeaf: mutableMyNode.leafOrder
    of voRoot: mutableMyNode.rootOrder
  
  for n in resultSeq:
    yield n


if isMainModule:
  let root = MyNode(
    name: "A1",
    children: @[
      MyNode(
        name: "B1",
        children: @[
          MyNode(name: "C1")
        ]
      ),
      MyNode(
        name: "B2",
        children: @[
          MyNode(name: "C2"),
          MyNode(
            name: "C3",
            children: @[
              MyNode(name: "D1")
            ]
          )
        ]
      )
    ]
  )

  for n in root.walk(voLeaf): echo n
  for n in root.walk(voLeaf): echo n # commenting this line avoids C codegen error

Current Output

CC: experiments.nim
/home/arkanoid/snap/codium/common/.cache/nim/experiments_d/@mexperiments.nim.c: In function ‘NimMainModule’:
/home/arkanoid/snap/codium/common/.cache/nim/experiments_d/@mexperiments.nim.c:1417:25: error: ‘colonenv_’ undeclared (first use in this function); did you mean ‘colonenv__2’?
 1417 |    asgnRef((void**) (&(*colonenv_).resultSeq1), newSeq_experiments_19(((NI) 0)));
      |                         ^~~~~~~~~
      |                         colonenv__2
/home/arkanoid/snap/codium/common/.cache/nim/experiments_d/@mexperiments.nim.c:1417:25: note: each undeclared identifier is reported only once for each function it appears in
Error: execution of an external compiler program 'gcc -c  -w -fmax-errors=3   -I'/home/arkanoid/.choosenim/toolchains/nim-#devel/lib' -I/home/arkanoid/nim/src -o /home/arkanoid/snap/codium/common/.cache/nim/experiments_d/@mexperiments.nim.c.o /home/arkanoid/snap/codium/common/.cache/nim/experiments_d/@mexperiments.nim.c' failed with exit code: 1

Expected Output

compilation successful

nim -v
Nim Compiler Version 1.5.1 [Linux: amd64]
Compiled at 2021-08-23
Copyright (c) 2006-2021 by Andreas Rumpf

git hash: 2d84f6e7c836bf18c0ecbe07fb413166861196ac
active boot switches: -d:release

[ghost]

might be a duplicate of #14165

[ringabout]

might be a duplicate of #14165

Indeed

After fixing #14165, the program gives

(name: "C1", children: @[], visited: false)
(name: "C2", children: @[], visited: false)
(name: "D1", children: @[], visited: false)
(name: "B1", children: @[(name: "C1", children: @[], visited: true)], visited: false)
(name: "C3", children: @[(name: "D1", children: @[], visited: true)], visited: false)
(name: "B2", children: @[(name: "C2", children: @[], visited: true), (name: "C3", children: @[(name: "D1", children: @[], visited: true)], visited: true)], visited: false)
(name: "A1", children: @[(name: "B1", children: @[(name: "C1", children: @[], visited: true)], visited: true), (name: "B2", children: @[(name: "C2", children: @[], visited: true), (name: "C3", children: @[(name: "D1", children: @[], visited: true)], visited: true)], visited: true)], visited: false)
(name: "C1", children: @[], visited: false)
(name: "C2", children: @[], visited: false)
(name: "D1", children: @[], visited: false)
(name: "B1", children: @[(name: "C1", children: @[], visited: true)], visited: false)
(name: "C3", children: @[(name: "D1", children: @[], visited: true)], visited: false)
(name: "B2", children: @[(name: "C2", children: @[], visited: true), (name: "C3", children: @[(name: "D1", children: @[], visited: true)], visited: true)], visited: false)
(name: "A1", children: @[(name: "B1", children: @[(name: "C1", children: @[], visited: true)], visited: true), (name: "B2", children: @[(name: "C2", children: @[], visited: true), (name: "C3", children: @[(name: "D1", children: @[], visited: true)], visited: true)], visited: true)], visited: false)