cast uncheckedAssign

Some restrictions for case objects can be disabled via a {.cast(uncheckedAssign).} section:

type
  TokenKind* = enum
    strLit, intLit
  Token = object
    case kind*: TokenKind
    of strLit:
      s*: string
    of intLit:
      i*: int64
proc passToVar(x: var TokenKind) = discard
var t = Token(kind: strLit, s: "abc")
{.cast(uncheckedAssign).}:
  # inside the 'cast' section it is allowed to pass 't.kind' to a 'var T' parameter:
  passToVar(t.kind)
  # inside the 'cast' section it is allowed to set field 's' even though the
  # constructed 'kind' field has an unknown value:
  t = Token(kind: t.kind, s: "abc")
  # inside the 'cast' section it is allowed to assign to the 't.kind' field directly:
  t.kind = intLit