`SIGSEGV` in `asyncTest`-derived scenario (also, in `asyncTest`)

[tersec]

import chronos    # only depends on asyncloop's transitive closure

proc t(): Future[int] {.async: (raw: true, raises: [ValueError]).} =
  var retFuture = newFuture[int]("")
  retFuture.fail(newException(ValueError, ""))
  return retFuture

proc m(transp: int): Future[void] {.async: (raw: true, raises: []).} =
  var retFuture = newFuture[void]("")
  retFuture.complete()
  return retFuture

proc p(self: int) {.async.} = await self.m()

try:
  defer: waitFor p(0)    # teardown
  waitFor((proc() {.async.} = discard await t())())  # asyncTest
except CatchableError:
  discard

Across all of Nim 1.6 refc and Nim 2.0 and devel refc and ORC:

rm ~/.cache/nim/ -rf && ~/nim16/bin/nim c -r /tmp/w; ~/nim20/bin/nim c -r --hints:off --mm:refc /tmp/w; ~/nim20/bin/nim c -r --hints:off --mm:orc /tmp/w; ~/nimdevel/bin/nim c -r --hints:off --mm:refc /tmp/w; ~/nimdevel/bin/nim c -r --hints:off --mm:orc /tmp/w
Traceback (most recent call last)
/tmp/w.nim(16)   w
SIGSEGV: Illegal storage access. (Attempt to read from nil?)
Segmentation fault
Error: execution of an external program failed: '/tmp/w'
Traceback (most recent call last)
/tmp/w.nim(16)   w
SIGSEGV: Illegal storage access. (Attempt to read from nil?)
Segmentation fault
Error: execution of an external program failed: '/tmp/w'
Traceback (most recent call last)
.nimble/pkgs2/chronos-4.0.0-2b7b9c774b0fb8c3b1d415da6148c8973c4ba81c/chronos/internal/asyncfutures.nim(217) w
SIGSEGV: Illegal storage access. (Attempt to read from nil?)
Segmentation fault
Error: execution of an external program failed: '/tmp/w'
Traceback (most recent call last)
/tmp/w.nim(16)   w
SIGSEGV: Illegal storage access. (Attempt to read from nil?)
Segmentation fault
Error: execution of an external program failed: '/tmp/w`
Traceback (most recent call last)
.nimble/pkgs2/chronos-4.0.0-2b7b9c774b0fb8c3b1d415da6148c8973c4ba81c/chronos/internal/asyncfutures.nim(217) hmm
SIGSEGV: Illegal storage access. (Attempt to read from nil?)
Segmentation fault
Error: execution of an external program failed: '/tmp/w'

Nim versions:

Nim Compiler Version 1.6.19 [Linux: amd64]
Compiled at 2024-03-03
Copyright (c) 2006-2023 by Andreas Rumpf

git hash: 51c86fdae77b6ebd9c9caf4924ec1edfe7883933
active boot switches: -d:release

Nim Compiler Version 2.0.3 [Linux: amd64]
Compiled at 2024-03-03
Copyright (c) 2006-2023 by Andreas Rumpf

git hash: e03667e92040bae8f8a7f817679a1abb4d19f4eb
active boot switches: -d:release

Nim Compiler Version 2.1.1 [Linux: amd64]
Compiled at 2024-03-03
Copyright (c) 2006-2024 by Andreas Rumpf

git hash: 1e7ca2dc789eafccdb44304f7e42206c3702fc13
active boot switches: -d:release

And this does trigger with the Chronos commit in nimbus-eth2, as well as the one one gets from cloning this repo in a default way.

[tersec]

Slightly less minimized version, showing the uinttest2 aspects more explicitly:

import ./asyncloop
import unittest2

proc connect(): Future[int] {.
             async: (raw: true, raises: [ValueError]).} =
  var retFuture = newFuture[int]("stream.transport.connect")
  retFuture.fail(newException(ValueError,
    "connect local address domain is not equal to target address domain"))
  return retFuture

proc closeWait(transp: int): Future[void] {.async: (raw: true, raises: []).} =
  var retFuture = newFuture[void]("stream.transport.join")
  retFuture.complete()
  return retFuture

type
  TcpTransport = object
    client: int

proc new(T: typedesc[TcpTransport]): T =
  return default(TcpTransport)

method stop(self: TcpTransport) {.async.} =
  discard await allFinished(@[self.client.closeWait()])

var stub: TcpTransport
suite "Tor transport":
  setup:
    stub = TcpTransport.new()
  teardown:
    waitFor stub.stop()

  test "test start and dial using ipv4":
    # asyncTest
    waitFor((
      proc() {.async.} =
        discard await connect()
    )())

But see above, unittest and its fun use of gcsafe and threadvar are not required to repro this.

[cheatfate]

The problem is not in unittest2, because last example is impossible to reproduce for me, but initial one is possible to reproduce on Linux and Windows with Nim 1.6.18.

[cheatfate]

I could also confirm that this (asyncdispatch version)

import asyncdispatch

proc t(): Future[int] =
  var retFuture = newFuture[int]("")
  retFuture.fail(newException(ValueError, ""))
  return retFuture

proc m(transp: int): Future[void] =
  var retFuture = newFuture[void]("")
  retFuture.complete()
  return retFuture

proc p(self: int) {.async.} =
  await self.m()

try:
  defer: waitFor p(0)    # teardown
  waitFor((proc() {.async.} = discard await t())())  # asyncTest
except CatchableError:
  discard

is working cc @arnetheduck

[arnetheduck]

simplified:

import chronos    # only depends on asyncloop's transitive closure

proc t(): Future[void] =
  var retFuture = newFuture[void]("")
  retFuture.fail(newException(ValueError, ""))
  return retFuture

proc m(transp: int): Future[void] =
  var retFuture = newFuture[void]("")
  retFuture.complete()
  return retFuture

proc p(self: int) {.async.} = await self.m()

try:
  try:
    waitFor(t())  # asyncTest
  finally:
    waitFor p(0)    # teardown
except CatchableError:
  discard

[arnetheduck]

Upstream bug: https://github.com/nim-lang/Nim/issues/23390

[bhartnett]

Would it be possible to workaround this issue within chronos without having to wait for the upstream Nim issue to be fixed?