Nim/tests/metatype/ttypedesc1.nim

import unittest, typetraits

type
  TFoo[T, U] = object
    x: T
    y: U

proc getTypeName1(t: typedesc): string = t.name
proc getTypeName2(t: type): string = t.name

proc foo(T: type float, a: auto): string =
  result = "float " & $(a.len > 5)

proc foo(T: typedesc[TFoo], a: int): string =
  result = "TFoo "  & $(a)

proc foo(T: type[int or bool]): string =
  var a: T
  a = 10
  result = "int or bool " & ($a)

template foo(T: typedesc[seq]): string = "seq"

test "types can be used as proc params":
  # XXX: `check` needs to know that TFoo[int, float] is a type and
  # cannot be assigned for a local variable for later inspection
  check ((string.getTypeName1 == "string"))
  check ((getTypeName2(int) == "int"))

  check ((foo(TFoo[int, float], 1000) == "TFoo 1000"))

  var f = 10.0
  check ((foo(float, "long string") == "float true"))
  check ((foo(type(f), [1, 2, 3]) == "float false"))

  check ((foo(int) == "int or bool 10"))

  check ((foo(seq[int]) == "seq"))
  check ((foo(seq[TFoo[bool, string]]) == "seq"))

template accept(x) =
  static: assert(compiles(x))

template reject(x) =
  static: assert(not compiles(x))

var
  si: seq[int]
  ss: seq[string]

proc foo(T: typedesc[seq], s: T) =
  discard

accept:
  foo seq[int], si

reject:
  foo seq[string], si

reject:
  foo seq[int], ss

# issue #12398
reject:
  let xs = [int, float, string]

reject:
  let data = @[int, typedesc]