Concept requirements ignored in some cases

[RedBeard0531]

This shouldn't compile but does with both 0.17.2 and devel:

type
  Holder[T] = object
  Concept[Arg] = concept c, type C
    c is C
    false

proc test(holder:Holder, _: Concept[holder.T]) = discard

test(Holder[string](), 1)

[RedBeard0531]

BTW, this is the real code I'm trying to make work:

  HashEqCompatible*[StorageType] = concept heq, type HEQ
    ## Declares types where a == b implies hash(a) == hash(b), even with
    ## different types. For example, string and cstring are compatible.
    mixin isHashEqCompatible
    HEQ is StorageType or
      isHashEqCompatible(type StorageType, type HEQ) or
      isHashEqCompatible(type HEQ, type StorageType)

    hash(heq) is Hash
    (heq == StorageType) is bool

The goal is that you need to explicitly opt in to being compatible because it isn't guaranteed by the signatures of the functions. Is there a better way to allow explicit opt-in to a Concept by a pair of types?