Crash when using thread and --gc:arc

[cdxf]

The following code works with default gc, but will crash after the first iteration when using --gc:arc

Example

import os

proc threadFunc(i:int ) {.thread.} =
  echo("Performing...")
  os.sleep(100)
when isMainModule:
  while true:
    echo("Starting...")
    var thr:  array[0..3, Thread[int]]
    for i in 0..high(thr):
      createThread(thr[i], threadFunc, i)
    joinThreads(thr)
    echo("Done...")

Current Output

Crash after first iteration

Expected Output

Perform next iteration

$ nim -v
Nim Compiler Version 1.2.0 [Windows: amd64]
(Tried on Linux too)

[cooldome]

works fine with the following fix #13897

[Clyybber]

For me on linux 64bit this deadlocks(?) with --gc:arc printing

Perform next iteration
Perform next iteration
Perform next iteration

but then hanging up.

It crashes instead of hanging up if you do --stacktrace:off FYI

[Araq]

Can reproduce.