NimYAML
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type mismatch in construction of sparse object
I ran into this bug. I think it may be a bug in the compiler, but I wanted to check with you first. Have you seen this before? Any clue?
It exist in many compiler versions back to 0.14.0.
fType[1].kind == nnkSym returns nnkBracketExpr in:
proc getOptionInner(fType: NimNode): NimNode {.compileTime.} =
if fType.kind == nnkBracketExpr and len(fType) == 2 and
fType[1].kind == nnkSym:
return newIdentNode($fType[1])
else: return nil
Simplified Example:
import yaml, streams
when not defined skipBad:
# this line is what is triggering it
# it can be in another module and not exported, but still trigger the problem
func `==`(a: Option[seq[string]], b: seq[string]): bool = discard
type
StrSeq = seq[string]
B {.sparse.} = object
c: Option[StrSeq]
d: string
var b: B
yaml.load(newStringStream("d: e"), b)
Current Output:
... yaml/serialization.nim(655, 29) Error: type mismatch: got <NimNode>
but expected one of:
proc none(T: typedesc): Option[T]
first type mismatch at position: 1
required type for T: typedesc
but expression 'nil' is of type: NimNode
proc none[T](): Option[T]
first type mismatch at position: 1
extra argument given
expression: none(nil)
It's a compiler bug:
proc hgjhgjhgjhg(a: Option[seq[string]], b: seq[string]): bool = discard
type
StrSeq = seq[string]
B = object
c: Option[StrSeq]
D = Option[StrSeq]
macro a(t: typedesc) =
doAssert t.getType.getTypeInst[1].kind == nnkSym
macro b(t: typedesc) =
doAssert t.getType[1].getType[2].children.toSeq[0].getTypeInst[1].kind == nnkSym
a D
b B
Even if this is a compiler bug, it affects NimYAML and therefore the issue should be kept open – there could exist a workaround that can be implemented in NimYAML.
Can you link an issue of the Nim compiler describing this bug?
Suddenly getting this error, even though all code worked before with the version I had used. Now, no version of NimYAML works anymore, because I always encounter this issue. Tried several commits from the past 3 months, I always end up at this error. A few commits cause additional issues, but these come before this one, so in the end, this is the biggest culprit.
How can I avoid this, without forking this project or tampering with the source code in the Nimble folder?
Ideally, I just want to nimble install this & have it work, just as before.
Error started happening, after I added another {.sparse.} object, but this does not make sense, because I already had another sparse object & it worked fine!
Thanks @theAkito, your comment on the Nim issue made me realize this can be fixed in NimYAML.
The type alias problem was simply a symptom of the real problem, which was that NimYAML wasn't able to process generic type instances in Option[…]. I pushed a fix and did some testing, the code shown in this issue now works. Can you confirm this fixes your problem as well (via pulling yaml@#head)? If so I will release a bugfix version.
Can you confirm this fixes your problem as well (via pulling
yaml@#head)? If so I will release a bugfix version.
Of course, will do, still today, but unfortunately not right now. Will return here ASAP!!