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

[filcuc]

without RootObject with Nim 1.6.2

type Foo = ref object

proc delete(self: Foo) 
proc newFoo: Foo = new(result, delete)
proc delete(self: Foo) = echo("delete Foo")

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

I get

No stack traceback available
To create a stacktrace, rerun compilation with './koch temp c <file>', see https://nim-lang.github.io/Nim/intern.html#debugging-the-compiler for details

[arkanoid87]

without RootObject with Nim 1.6.2

type Foo = ref object

proc delete(self: Foo) 
proc newFoo: Foo = new(result, delete)
proc delete(self: Foo) = echo("delete Foo")

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

I get

No stack traceback available
To create a stacktrace, rerun compilation with './koch temp c <file>', see https://nim-lang.github.io/Nim/intern.html#debugging-the-compiler for details

see #19401

[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