latest yaml doesn't compile in latest nim

[kobi2187]

Does it work for you? I get:

/home/kobi7/.nimble/pkgs/yaml-#head/yaml/serialization.nim(218, 18) template/generic instantiation of `constructObject` from here
/home/kobi7/.nimble/pkgs/yaml-#head/yaml/serialization.nim(194, 15) template/generic instantiation from here
/home/kobi7/.nimble/pkgs/yaml-#head/yaml/serialization.nim(146, 33) Error: can raise an unlisted exception:

I don't know what's wrong. something is amiss with the pragma raises. if it's only on my computer, can we debug this together? I would like to still use yaml files in my project.

[flyx]

Is there no additional information after the last error line you posted?

Also, your sources do not seem to be up-to-date. serialization.nim:218 is an empty line and cannot possibly produce an error. Try updating with nimble.

[kobi2187]

the line numbers are different because I use vscode, which automatically runs nimpretty. I reinstalled it just to make sure. Now I get these lines:

/home/kobi7/.nimble/pkgs/yaml-#head/yaml/serialization.nim(159, 15) template/generic instantiation from here
/home/kobi7/.nimble/pkgs/yaml-#head/yaml/serialization.nim(146, 33) Error: can raise an unlisted exception:

[kobi2187]

It is strange that the compiler complains about a missing exception, but then cannot tell me which one.

[flyx]

Indeed. Are you on Nim devel? If so, maybe check with Nim devs first (IRC or issue tracker). The compiler not telling you which exception it misses hints to a problem in the compiler.

Did you try to compile on command line without vscode? I think it's very strange that the vscode plugin reformats imported code; that should be just forbidden. Anyway, it can also be that vscode cuts away an additional error information line.

[kobi2187]

yes, on nim devel. I compiled from the command line. at first I thought it was because of -d:ssl that I used in my code, but cwd to yaml pkg, and nim c yaml.nim gave the same error. the vscode plugin reformats any nim file that you have opened, immediately before saving it. about the missing information line, I suspected vscode's inner terminal too, but it appears exactly the same in a regular bash "gnome-terminal". if I have some time I'll file a bug report, see what they think. Thanks!

[kobi2187]

filed a bug report: https://github.com/nim-lang/Nim/issues/10579

[kobi2187]

they're so fast. ok, so there is a stopgap fix in the nim compiler. I am not sure it's optimal, now it reports Exception is missing. I think we can change the code later when nim improves further. I just added Exception in all the raises that were referenced in the errors. https://github.com/kobi2187/NimYAML/commit/ddacd98cf71b44bfa7cdb50a01a1aa13ab01ab3c

Would you like a pull request? I am new to git and not sure why it tells me I am 2 commits behind and 3 ahead, or how to fix it.

[narimiran]

I've just run into the same problem. I've bisected Nim devel branch to see when this stopped working, and it is https://github.com/nim-lang/Nim/commit/3ce6b2acb9ce21d33f0f14161b0abf89a9ff7af9 (cc @LemonBoy).

Here is a code block from serialization.nim where (first) error occurs:

template constructScalarItem*(s: var YamlStream, i: untyped,
                              t: typedesc, content: untyped) =
  ## Helper template for implementing ``constructObject`` for types that
  ## are constructed from a scalar. ``i`` is the identifier that holds
  ## the scalar as ``YamlStreamEvent`` in the content. Exceptions raised in
  ## the content will be automatically catched and wrapped in
  ## ``YamlConstructionError``, which will then be raised.
  bind constructionError
  let i = s.next()
  if i.kind != yamlScalar:
    raise constructionError(s, "Expected scalar")
  try: content
  except YamlConstructionError: raise ###################### "Error: can raise an unlisted exception: Exception"
  except Exception:
    var e = constructionError(s,
        "Cannot construct to " & name(t) & ": " & item.scalarContent &
        "; error: " & getCurrentExceptionMsg())
    e.parent = getCurrentException()
    raise e

Similar stuff happens on line 1224, in this block:

  case e.kind
  of yamlScalar: removeAnchor(e.scalarAnchor)
  of yamlStartMap: removeAnchor(e.mapAnchor)
  of yamlStartSeq: removeAnchor(e.seqAnchor)
  else: internalError("Unexpected event kind: " & $e.kind)
  s.peek = e
  try: constructChild(s, c, result[])
  except YamlConstructionError, YamlStreamError: raise ############### "Error: can raise an unlisted exception: Exception"
  except Exception:
    var e = newException(YamlStreamError, getCurrentExceptionMsg())
    e.parent = getCurrentException()
    raise e

If you change that line to something like except YamlConstructionError: raise constructionError(s, "foo"), then this works, but the next error is here:

proc construct*[T](s: var YamlStream, target: var T)
    {.raises: [YamlStreamError].} =
  ## Constructs a Nim value from a YAML stream.
  var context = newConstructionContext()
  try:
    var e = s.next()
    yAssert(e.kind == yamlStartDoc)

    constructChild(s, context, target)
    e = s.next()
    yAssert(e.kind == yamlEndDoc)
  except YamlConstructionError:
    raise (ref YamlConstructionError)(getCurrentException())  ################### "Error: can raise an unlisted exception: ref YamlConstructionError"
  except YamlStreamError:
    let cur = getCurrentException()
    var e = newException(YamlStreamError, cur.msg)
    e.parent = cur.parent
    raise e
  except Exception:
    # may occur while calling s()
    var ex = newException(YamlStreamError, "")
    ex.parent = getCurrentException()
    raise ex

[LemonBoy]

Yeah, previously the compiler completely failed to compute what exceptions are raised and what are caught by a try/catch/finally block. Re-raising an exception with raise now correctly warns that either RaiseError or a generic one will be raised (we just say Exception since the former is a subclass). Even though the raise is in a except branch the compiler is not (yet) able to find out what specific exception type it will raise.

[kitech]

Lastest, seems queues module is gone Error: cannot open file: queues

$ nim -V
Nim Compiler Version 0.19.9 [Linux: amd64]
Compiled at 2019-05-03
Copyright (c) 2006-2019 by Andreas Rumpf

active boot switches: -d:release

[kobi2187]

yes, in presenter.nim: you need to replace it with deques and change a few calls to the correct api. I've had little time on my hands to send a pr - here's how to solve it

proc nextItem(c: var Deque, s: var YamlStream):

try: result = c.popFirst cached = initDeQue[YamlStreamEvent]() cached.addLast(next)

[flyx]

This should be fixed with #71.