Mirror of forum.nim-lang.org

1242 :: Parser bug?

• FedeOmoto1 (orginal) [2015-05-18T20:10:31+02:00] view original

  Hi!

  The following code fails to compile:

  proc test(a, b: int | int64) =
    discard
  
  test(1.int, 2.int64)
  Run

  with this error:

  a.nim(4, 5) Error: type mismatch: got (int, int64)
  but expected one of:
  a.test(a: int or int64, b: int or int64)

  While the following code compiles OK:

  proc test(a: int | int64, b: int | int64) =
    discard
  
  test(1.int, 2.int64)
  Run

---

• def (orginal) [2015-05-18T20:13:32+02:00] view original

  Should be this bug: https://github.com/Araq/Nim/issues/1385

---

• yglukhov (orginal) [2015-05-20T09:07:15+02:00] view original

  Does this sample look normal only to me? First declaration implies that a and b are of the same type whether it is int or int64. While the second sample says that a and b have independent types. The error message is not consistent however.

---

• andrea (orginal) [2015-05-20T09:21:14+02:00] view original

  If I interpret correctly, int | int64 is a union type, whose members are those that are members of int or those that are members of int64.

  The first version requires that both a and b are members of this union type, hence it implies no relationship among them. If the | notation was only a shortcut, your interpretation would make sense, but the point is that (I think) int | int64 is a type on its own

---

• filwit (orginal) [2015-05-20T10:38:22+02:00] view original

  @andrea: I'm not so sure, int|int64 might just be sugar for generics, eg: proc test[T:int|int64](a, b:T) in which case 'T' is caught once before checked against 'a' or 'b', requiring them both to share type. While the second version would be sugar for proc test[T:int|in64, U:int|int64](a:T, b:U) and therefore their types can differ.

---