Cyclic initialization compiles with -Yexplicit-nulls and -Ysafe-init

[crater2150]

Compiler version

3.0.0-M3-bin-20201216-c8fb1fa-NIGHTLY-git-c8fb1fa

Minimized code

object A { val x: String = B.y }
object B { val y: String = A.x }

Output

Compiled with both -Yexplicit-nulls and -Ysafe-init, both fields are null:

A.x == null
B.y == null

Expectation

I expected this not to compile. I'm not sure if detecting such cycles is in scope for -Ycheck-init, but the documentation for explicit nulls suggests that -Ycheck-init catches the unsoundness caused by null in initialization.

[liufengyun]

This can now be checked with the experimental option: -Ysafe-init-global.