NNBD. Dart crashes on late variables

[sgrekhov]

class C {
  num pi = 3.14;
  late num p1 = this.pi;
  late final p2 = this.pi;
}

main() {
  new C().p1;
  new C().p2;
}

Run this code in dart with --enable-experiment=non-nullable flag and there will be a crach! Tested on

Dart VM version: 2.7.0-dev.2.1 (Mon Dec 2 20:10:59 2019 +0100) on "windows_x64"
Dart VM version: 2.7.0-dev.2.1 (Unknown timestamp) on "linux_x64"

[liamappelbe]

Interesting. This is only reproducible if the late variable is a double. Ints and classes work fine.

[liamappelbe]

It seems that when doubles are unboxed it messes with the late field logic. So the fix is just to disable unboxing for late fields, like we do for final fields.

[sgrekhov]

@liamappelbe, I have one more test that produces a CRASH on late variables, but without double values. It tests that "It is an error for a class with a const constructor to have a late final field". And dart --enable-experiment=non-nullable crashes on this code on both Windows and Linux.

class C {
  static late final int s = 42;
//       ^^^^
// [analyzer] unspecified
// [cfe] unspecified

  late final int i = 42;
//^^^^
// [analyzer] unspecified
// [cfe] unspecified
  const C();
}

main()  {
  C();
}

Does your fix fixes this issue as well? If need I can create a separate issue for this, just let me know

[sgrekhov]

@liamappelbe One more crash on late for strings

class A {
  String s;
  A(this.s);
}

class C {
  A a = new A("Lily was here");
   late A a1 = this.a;
}

main() {
  new C().a1;
}

Is this a separate issue?

[liamappelbe]

The first one sounds like an analyzer bug, so file a separate issue (other people are working on that part).

The second one works for me, with or without the fix in e20ff1e, so that's a separate issue. Can you try syncing to head and file a bug if it's reproducible?

[sgrekhov]

There are no crash any longer for all of the cases mentioned above. Tested on Dart VM version: 2.8.0-dev.0.0 (Wed Dec 11 10:31:10 2019 +0100) on "windows_x64". Thank you.