Crashes in VB6

[SanbiVN]

I used your code library in VB6. I encountered a crash issue.
I implemented the Dictionary object variable call through a recursive function.

Private Function PaneList(ByVal panes As Collection, Optional listed As Dictionary) As Integer
  Dim p, s$
  For Each p In panes
    s = ObjPtr(p)
    If Not listed.Exists(s) Then
       listed.Add s, ""
       PaneList p.panes, listed
    End If
  Next
End Function

My project has a large amount of source code, and I only encounter problems if I don't call your Dictionary class.

[cristianbuse]

I do not have VB6 to test with. Can you replicate the crash in VBA? if yes, can you provide a minimal example that I can just run? I don't have your "panes" class so cannot test.

[SanbiVN]

My project uses UserControls, so it's impossible to replicate this in VBA.

I used the following method: inputting an array of value, and the array list contains a class object, as follows:

Dim Pane as New Class1
dict.add CStr(objPrt(Pane)), Array(a1, a2, pane)

This causes a crash. It causes problems for the entire IDE.
In the GIF image, the IDE crashed after closing the application.

If I don't put the array into the Dictionary item, there are no problems.

[cristianbuse]

I wonder if your zzzzWinView3Pane class is not memory leaking. Make a copy of the class and name it zzzzWinView3PaneTest. Then replace your line with tDict.Add "hello", Array(1, 2, 3, 4, New zzzzWinView3PaneTest. Then start removing methods from the test class until there is no crash. This should allow you to isolate the problem.

[SanbiVN]

I tested an empty class. The problem still occurs.

Simply entering the following array will cause an error:

   tDict.Add "hello", Array(1, 2, 3, 4)

[cristianbuse]

Works fine in VBA. Unfortunately I do not own VB6 so it's impossible for me to test.

[SanbiVN]

I only wrote the application in VB6 as a draft for a modern C++ application. So the issue isn't that important.
Thank You Too!

[olivebn]

Hi @cristianbuse ,

I also have a crash in VB6 that is not related to my code but directly to Dictionary.

if i run only this code :

Public Sub Main()
Dim d As Dictionary
'
Set d = New Dictionary
Set d = Nothing
End Sub

I have a crashed after the code exit the sub

In IDE+Source : it crashes the IDE
In Exe build : i have an error message 91 “Object variable or With block variable not set”

The crash seem to come from this code :

    Else 'Insert after last terminated
        Mem.RPtr(0) = insertAfterPtr
        .saP.pvData = insertAfterPtr + .nextPtrOffset
        '
        Dim tempPtr As LongPtr: tempPtr = Mem.RPtr(0)
        Mem.RPtr(0) = pendingPtr
        '
        .saP.pvData = tempPtr + prevOffset
        Mem.RPtr(0) = pendingPtr
        '
        .saP.pvData = pendingPtr + .nextPtrOffset
        followPtr = Mem.RPtr(0)
        Mem.RPtr(0) = tempPtr
        '
        If prevPtr <> NullPtr Then 'Not first ever instance
            .saP.pvData = prevPtr + .nextPtrOffset
            Mem.RPtr(0) = followPtr
        End If
        '
        .saP.pvData = followPtr + prevOffset
        Mem.RPtr(0) = prevPtr
        followPtr = tempPtr
    End If

In standard run, build or in ide it crash on the first line after Else
In step by step debug it rises not always on the firt line but frequently on one of the "Mem.RPtr(0) = " lines.

Note : on the same machine with the same class in Excel VBA i never had the problem.

Note2 : if i directly stop VB6 engine with a "End" instruction just before "End Sub" i have no crash, but i thing because "End" stop the process without executing _terminate instructions on instances.

If you think about something i can do or if you want to take a look i would be pleased.

Regards,

Olivier

[cristianbuse]

Hi @olivebn ,

Presumably the code in VB6 is not compiled but rather running in IDE?

Do you know if there is any way to get a VB6 trial license? I don't know how else I could replicate and test this kind of issues without actually having VB6 installed.

Thanks!

[olivebn]

Hi @cristianbuse thanks for you reply,

I had no email notification about your response, it's why i just reply now, i'll look about it later.

The problem exists running in IDE and also in build exe.

In build exe the code is compiled, i tried the different build options but there's no change.

I'll take a look but i don't think there's a way to get a trial for VB6, to my knowledge the only way to have VB6 today is with an MSDN subscription.

In case you want to just take a quick look at the problem i can propose to teams with you to show you.

Thanks

[cristianbuse]

@olivebn

Apologies for the late reply. Thank you for your suggestion but I doubt I would be able to figure out the issue via Teams. I've done sessions with other people before and it's too difficult to debug like this.

If you want, I can create some code for you to run independently from the Dictionary, just to check if the class structure is the same in VB6 when compared to VBA. Please let me know.

[olivebn]

Hi @cristianbuse don't apologies, i'm grateful you spend time on my problem ;)

I propose that i'll do some other tests and come back to you with results.

I didn't know about twinBasic before but i took a quick look and try also the same code with it.

After i would be pleased that you give me some code to check.