Finalizer not called for type ref object of RootObj when using ARC/ORC + Forward declaration

[arkanoid87]

Example

compile with --gc:arc

type Foo = ref object of RootObj
proc delete(self: Foo) 
proc newFoo: Foo = new(result, delete)
proc delete(self: Foo) = echo("delete Foo")

if isMainModule:
  proc test() = discard newFoo()
  test()

Current Output

none

Expected Output

delete foo

Additional Information

Tested nim version 1.4.2 up to devel (15e3813)

It works with --gc:refc, it gives a different problem if type Foo = ref object (see #19401)

[filcuc]

This impact NimQml. See
filcuc/nimqml#43
filcuc/nimqml#42

[ringabout]

Workaround: use codeReordering

{.experimental: "codeReordering".}

type Foo = ref object of RootObj
proc delete(self: Foo)  # it can be omitted
proc newFoo: Foo = new(result, delete)
proc delete(self: Foo) = echo("delete Foo")

if isMainModule:
  proc test() = discard newFoo()
  test()

[filcuc]

@xflywind it seems code reordering is not enough for making NimQml work..probably code reordering is experiemental for a reason :D

[ringabout]

Yeah, I agree. It needs a real fix.

[filcuc]

@Araq and @xflywind any tip for debugging this one. Maybe i can try to look and debug this one in the compiler but a couple of hints could increase my success chances. I quickly skimmed the output in the c files but didn't noticed anything interesting (or maybe failed to understand them).

[Araq]

Look at lifdestructors.nim and maybe at injectdestructors.nim

[ringabout]

Hello, @filcuc Here is the progress => #20295, but I cannot try it out with nimQML

[filcuc]

@ringabout i'll try your fix asap

[filcuc]

@ringabout i've tested it and it works! nice!!!

[filcuc]

@ringabout the only thing i've notice is that even if i'm using orc/arc deletion of object is not called immediately. However if i make a call to GC.forceFullCollect i see the finalizers being called...seems like something is "deferring" the deletion