using ImGuiListClipperPtr triggers AccessViolationException after upgrading to 1.89

[pixtur]

Hi,

after upgrading to v1.89.5 the following code causes as System.AccessViolationException:

  unsafe
  {
      var clipperData = new ImGuiListClipper();
      var listClipperPtr = new ImGuiListClipperPtr(&clipperData);
      listClipperPtr.Begin(items.Count, ImGui.GetTextLineHeightWithSpacing());
   }

Maybe I'm using the API in an unintended way, but it I assume something changed in the implementation. This could also be on the ImGui side, but I'm not good enough with C to write an example.

[zaafar]

was it working before 1.89.5?

[pixtur]

after upgrading to 1.89

Good point I only tested 1.88.0 and 1.87.3. v1.88 also triggers the exception. v1.87.3 works.

I know it's kind of too much work to ask for, but these were me steps to reproduce:

1. clone https://github.com/still-scene/t3/tree/dev
2. Upgrade nuget package
3. Start Editor and then open Window -> Console from Tooll's app menu.

[zaafar]

I just tested imgui.net version 1.89.4 (which points to cimgui 1.89.2) and its working fine. Looks like it broke in the last upgrade (i.e. imgui.net version 1.89.5 which points to cimgui 1.89.5).

i will dig more and try to figure out what changed between these 2 versions that broke it...

[zaafar]

the only thing that changed was as following.

[zaafar]

==debugging+fixing the issue==

-> lets go into this function

-> lets go into this function

-> lets go into this cimgui (c language) function.

-> according to this c++ (imgui function), looks like Ctx isn't initialized and it is suppose to be.

[zaafar]

==solution==

i am not sure if this is how we should do it....or if this is the right ctx to use but this is one possible solution.

[zaafar]

interesting read: https://github.com/ocornut/imgui/commit/c8ad25caa6bfcb786085a76e67a7f31e61a80cb7 -> https://github.com/ocornut/imgui/pull/5856

[pixtur]

Oh wow. Thanks for looking into that so quickly! I'm not in a rush to upgrade, so I can wait until there is a final fix.

[zaafar]

the workaround is here (https://github.com/ImGuiNET/ImGui.NET/issues/401#issuecomment-1566216444) if you want to use that while waiting for a final fix.

[TheLostTree]

https://github.com/ImGuiNET/ImGui.NET/issues/393#issuecomment-1528692332 this should work also

[zaafar]

If you do that, you have to call the c++ destructor function as well. Just FYI.

[ocornut]

I have also pushed a workaround on dear imgui side: https://github.com/ocornut/imgui/commit/e95d66faa8e6c0255572632f34fad97a32f680cd

[zaafar]

Closing this issue as it will be fixed automatically once imgui.net is upgraded to the latest (unreleased) version.