Another typedesc issue, manifesting at runtime

[mratsim]

This is a followup on #4.

Last week the fix worked on my machine (I'm like 99% sure). This week it doesn't, I have a runtime exception when parsing.

This exception only happen when the type is passed as typedesc.

The branch is the same as before: https://github.com/status-im/nim-beacon-chain/tree/serialization_typedesc

• Commit: status-im/nimbus-eth2@1f4c4e8

• Travis: https://travis-ci.org/status-im/nim-beacon-chain/jobs/533372351#L1268-L1271

And screenshots:

Working

Failing

[mratsim]

The simple change from

proc parseTests*(jsonPath: string): ShufflingTests =
  result = Json.loadFile(jsonPath, ShufflingTests)

to

proc parseTests*(jsonPath: string, T: typedesc = ShufflingTests): ShufflingTests =
  result = Json.loadFile(jsonPath, ShufflingTests)

will change the test from a pass to a stacktrace:

test_fixture_shuffling.nim(25) test_fixture_shuffling
serialization.nim(101)   parseTests
serialization.nim(46)    readValue
reader.nim(181)          readValue
object_serialization.nim(90) :anonymous
reader.nim(154)          readValue
reader.nim(181)          readValue
object_serialization.nim(90) :anonymous
reader.nim(171)          readValue
reader.nim(102)          skipToken
reader.nim(91)           requireToken
reader.nim(64)           raiseUnexpectedToken

    Unhandled exception:  [UnexpectedToken]

And generics instead of typedesc also fails

[zah]

This is the same issue, Mamy.
I guess I should thank you for proving my point in nim-lang/Nim#11225 that the underlying Nim issue is quite hard for the user to figure out.