Unowned ref can trivially escape without causing any crashes

[alaviss]

Example

proc test(): RootRef =
  let r: owned RootRef = RootRef()
  result = r
  # discard r # uncomment this and the code will crash on runtime (as expected)

echo test()[]

Current Output

()

Expected Output

Either stopped at compile time or

[FATAL] dangling references exist

Additional Information

Nim Compiler Version 0.19.9 [Linux: amd64]
Compiled at 2019-04-25
Copyright (c) 2006-2019 by Andreas Rumpf

git hash: 1f7615ad9db3e8f90b20aa9932c3c11ee1793218
active boot switches: -d:release -d:useLinenoise -d:nativeStackTrace