unifyVars/kind Inference UCM exception

[lJoublanc]

Describe and demonstrate the bug

scratch/main> builtins.merge

ability Columns Dimension n where
  toNat : Dimension n -> {Columns (Dimension n)} Nat


structural type Dimension a = Zero | Succ a


zero = Zero

one = Dimension.Succ zero

two = Dimension.Succ one

three = Dimension.Succ two

This results in:

cratch/main> 

  Loading changes detected in ~/src/unison/scratch.u.

Encountered exception:
[unifyVars] unknown type in decl result: ReferenceDerived (Id "nirp5os0q69o4e1u9p3t6mmq6l6otluefi3ksm7dhm0diidjvkkgl8o9bvnflbj0sanuvdusf34f1qrins3ktcaglpcqv9oums2slsg" 0) (Var User "n")
CallStack (from HasCallStack):
  error, called at src/Unison/KindInference/Generate.hs:322:22 in unison-parser-typechecker-0.0.0-8PuoNWnGNyC8ffAZv1fPhx:Unison.KindInference.Generate

Screenshots n/a

Environment (please complete the following information):

• unison version: release/0.5.37 (built on 2025-03-27)
• OS/Architecture: Linux nizuc 6.8.0-58-generic 60-Ubuntu SMP PREEMPT_DYNAMIC Fri Mar 14 18:29:48 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux

Additional context I saw there is a bug #5453 and I'm not sure if this is a duplicate.