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336 :: ast not what I expected

• hiteshjasani (orginal) [2014-01-08T01:58:05+01:00] view original

  I'm hacking my way around the compiler focusing on type traits and I'm seeing different behavior depending on whether I'm trying to work with a type such as a Tuple or a proc. The following code will work for the tuple but not the proc.

  import typetraits as tt
  
  type TMyTuple = tuple[a, b: int, c: string]
  proc foo(i: int): int = i + 2
  
  echo "name = ", tt.name(TMyTuple)     # prints 'name = TMyTuple'
  echo "name = ", tt.name(type(foo))    # compiler error in semmagic.nim semTypeTraits()
  Run

  I know why I get the error only for the proc. The tuple gets correctly parsed as an nkSym and skType. However, the proc comes in as a tree of nkTypeOfExpr / nkPar / nkIdent rather than as a node of nkSym and skProc, which is what I would expect.

  Can someone help shed some light on why this is the case?

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• Araq (orginal) [2014-01-08T19:47:05+01:00] view original

  Sorry, no I can't right now. Maybe it's already fixed in the devel branch though.

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• hiteshjasani (orginal) [2014-01-08T23:49:15+01:00] view original

  Good news, it does work in the devel branch. Thanks.

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• hiteshjasani (orginal) [2014-01-09T06:01:39+01:00] view original

  Looking through the AST when in semTypeTraits() I noticed that any nkSym PNodes and nkIdent PNodes will report sonsLen() of 4480072496 and 4480076040, respectively. I noticed this behavior on the master branch as well as the devel branch.

  Those seem high compared to all the other PNodes which have 0 to 3 number of sons. Is this a bug or expected?

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• Araq (orginal) [2014-01-09T07:13:29+01:00] view original

  Not sure what you mean by "looking through" (using GDB?) but you must not call len/sonsLen on an atomic node. In debug mode this raises an EInvalidField exception. So no bug here, but you're misinterpreting some memory location.

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• hiteshjasani (orginal) [2014-01-10T00:08:47+01:00] view original

  I was just echoing out to stdout trying to learn how the data structures are set up and used. So I'm seeing stuff like this and trying to build a model in my head of how things are working.

  ---type = [k = tyTypeDesc, basetypes = 1, n=nil]
  -------type = [k = tyProc, basetypes = 2]
  -----------PNode, kind = [nkFormalParams], type = [], sonsLen = 2
  -------------PNode, kind = [nkArgList], type = [k = tyInt, s_n = int, s_k = skType], sonsLen = 4
  ---------------PNode, kind = [nkArgList], type = [], sonsLen = 0
  ---------------PNode = nil
  ---------------PNode = nil
  ---------------PNode, kind = [nkArgList], type = [], sonsLen = 0
  -------------PNode, kind = [nkSym], type = [k = tyInt, s_n = int, s_k = skType], sym = [i,skParam]
  -----------type = [k = tyInt, s_n = int, s_k = skType, basetypes = 0, n=nil]
  -----------type = [k = tyInt, s_n = int, s_k = skType, basetypes = 0, n=nil]
  Run

  Yeah, I see the exception now when compiling it in debug mode. Good to know.

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