nimvm: CritBitTree does not work: "limited VM support for 'addr'"

[akavel]

The CritBitTree type does not work at compile time.

Example

import critbits
static:
  var strings: CritBitTree[int]
  discard strings.containsOrIncl("foo", 1)
  echo strings["foo"]

Current Output

stack trace: (most recent call last)
C:\prog\dali\q_ct01.nim(5, 15) q_ct01
C:\Users\Mateusz\.choosenim\toolchains\nim-1.2.0\lib\pure\collections\critbits.nim(196, 3) []
C:\Users\Mateusz\.choosenim\toolchains\nim-1.2.0\lib\pure\collections\critbits.nim(196, 3) Error: limited VM support for 'addr'

Expected Output

1

Additional Information

• I am using CritBitTree in my project dali, which allows emitting Android .dex files from Nim. I would like to be able to emit .dex files at compile time, when writing Android apps in Nim. Currently, I have to instead:
  • generate strings with Nim code and emit them to a helper file,
  • compile and run this auxillary file separately to generate the final .dex file.

Nim version:

C:\prog\dali>nim -v
Nim Compiler Version 1.2.0 [Windows: amd64]
Compiled at 2020-04-03
Copyright (c) 2006-2020 by Andreas Rumpf

git hash: 7e83adff84be5d0c401a213eccb61e321a3fb1ff
active boot switches: -d:release

[ringabout]

@akavel
Workaround:

import critbits

proc getKey*[T](c: CritBitTree[T], key: string): T {.inline.} =
  c[key]

static:
  var strings: CritBitTree[int]
  discard strings.containsOrIncl("foo", 1)
  echo strings.getKey("foo")

https://play.nim-lang.org/#ix=2rsd

[timotheecour]

reduced without stdlib:

when true:
  type
    Node = ref object
      val: int
  proc bar(c: Node): var int =
    var n = c # Error: limited VM support for 'addr'
    c.val
  proc main =
    var a = Node()
    discard a.bar()
  static: main()
  main()

[akavel]

@timotheecour ❤️ thanks for working on this!