[SOLVED] Access Violation error on toggle Unit View / Form View

[perAspera]

Hello! I converted a large and old Delphi 5 project (30+ years of history including the TurboPascal era...) to Lazarus 2.0.6 on Win10. It worked surprisingly well, it compiles and (partially) runs already - that's great, many thanks 

However, there is a strange error I cannot explain or isolate: when I toogle between unit view and form view (the 5th button on the IDE) I get the error message:
Read error
In file
(filename...)
Access violation
Access violation

When I press Cancel, it appears again.
When I press Cancel again, I get:
Lazarus IDE v2.0.6 r62128 - opa
Access violation
Press OK to ignore and risk data corruption.
Press Abort to Kill the program.
(opa is the name of my program)
If I press Abort, then IDE kills itself.
If I press OK, I can continue, but I never see the Form. But I can compile and run my code and the Form looks as expected.

• This happens only for the main menu form of my code, all other Forms can toggle well between Unit and Form View.
• It also happens when I start Lazarus by clicking the .lpr or .lpi (I guess because the IDE tries to show the Form).

Probably it is something very obvious and stupid, but I'm a newbie, so any suggestion is appreciated 

[JuhaManninen]

Do you have Sparta DockedFormEditor installed?
In that case see:
 https://bugs.freepascal.org/view.php?id=33772
and its related issues.
If you don't have it installed then we have a new bug and need more information (debugger backtrace or steps to reproduce).

[winni]

Hi!

Have some files  belonging to the project set the readonly bit?

Winni

[wp]

Do the components on this form have properties which were not converted correctly to Lazarus?

Try to compile and run the project. Maybe an error is reported at runtime which is more descriptive, or you can use the debugger to isolate the issue.

[perAspera]

Thanks for the replies!

• I guess I don't have the Sparta DockedFormEditor because I cannot reproduce the error according to the instructions in the link.
• I will check for the readonly bit (have to figure out, I'm a newbie...)
  
• Indeed there are more errors at runtime but now I reduced the program to the absolute minimum (there is nothing to run anymore) and the bug is still there.
  [/i]
  

I removed everything not needed. I edited the *.lfm manually (because I cannot edit the form in the IDE) and I still see the bug.

Please find below the opa.lpr the main program, opamenu.pas and opamenu.lfm the form and opa.lpi. I guess this 4 files are sufficient to reproduce the problem? I also attached a pic how the form looks like. Perhaps somebody can see what went wrong?

As I said, despite the error the full program compiles and runs partially. Of course there are more bugs, and I would like to figure out if these are caused  by this one .

Please tell me or point me to a link how to generate the information which may be better suited for the developers to track the bug.

Many thanks!

opa.lpr

Code: Pascal  [Select][+][-]

1. program opa;
2.  
3. //{$MODE Delphi}
4.  
5. uses
6.   Forms, Interfaces,
7.   opamenu in 'opamenu.pas' {Menu};
8. //{$R *.res}
9.  
10. begin
11.   Application.Initialize;
12.   Application.Title := 'OPA';
13.   Application.CreateForm(TMenu, Menu);
14.  
15.   Application.Run;
16. end.                          
17.  

opamenu.pas

Code: Pascal  [Select][+][-]

1. unit opamenu;
2.  
3. interface
4.  
5. uses
6.   LCLIntf, LCLType, SysUtils, Forms, Dialogs, Menus, StdCtrls, ComCtrls,  ExtCtrls,  Imglist,  ActnList;
7.  
8. type
9.  
10.  
11.   { TMenu }
12.  
13.   TMenu = class(TForm)
14.     MainMenu1: TMainMenu;
15.     mi_file: TMenuItem;
16.     fi_open: TMenuItem;
17.     fi_save: TMenuItem;
18.     fi_svas: TMenuItem;
19.     fi_exit: TMenuItem;
20.     N1: TMenuItem;
21.     OpenDialog1: TOpenDialog;
22.     SaveDialog1: TSaveDialog;
23.     ed_text: TMenuItem;
24.     errlog: TMemo;
25.     LabFi0: TLabel;
26.     LabFileName: TLabel;
27.     LabSg0: TLabel;
28.     comboSeg: TComboBox;
29.     butlatsh: TButton;
30.     fi_new: TMenuItem;
31.     fi_last: TMenuItem;
32.     fi_expo: TMenuItem;
33.     mi_edit: TMenuItem;
34.     mi_desi: TMenuItem;
35.     mi_trac: TMenuItem;
36.     mi_extr: TMenuItem;
37.     tm_geo: TMenuItem;
38.     tm_cur: TMenuItem;
39.     tr_phsp: TMenuItem;
40.     tr_dyna: TMenuItem;
41.     tr_ttau: TMenuItem;
42.     ds_opti: TMenuItem;
43.     ds_sext: TMenuItem;
44.     ed_oped: TMenuItem;
45.     tm_test: TMenuItem;
46.     panstatus: TPanel;
47.     labstflag: TLabel;
48.     labstelem: TLabel;
49.     labstdata: TLabel;
50.     ds_lgbo: TMenuItem;
51.     ds_orbc: TMenuItem;
52.     ds_injc: TMenuItem;
53.     ds_dppo: TMenuItem;
54.     ds_rfbu: TMenuItem;
55.     ex_tracy2: TMenuItem;
56.     ex_tracy3: TMenuItem;
57.     ex_elegant: TMenuItem;
58.     ex_madx: TMenuItem;
59.     ex_bmad: TMenuItem;
60.  
61.   public
62.     { Public-Deklarationen }
63.   end;
64.  
65. var
66.   Menu: TMenu;
67.  
68. implementation
69.  
70. {$R *.lfm}
71.  
72. end.
73.  

opamenu.lfm

Code: XML  [Select][+][-]

1. object Menu: TMenu
2.   Left = 312
3.   Top = 547
4.   Width = 642
5.   Height = 395
6.   Caption = '  OPA 4.0 development version 51'
7.   Color = clMenu
8.   Font.Charset = DEFAULT_CHARSET
9.   Font.Color = clWindowText
10.   Font.Height = -16
11.   Font.Name = 'MS Sans Serif'
12.   Font.Style = [fsBold]
13.   Menu = MainMenu1
14.   PixelsPerInch = 96
15.   object LabFi0: TLabel
16.     Left = 64
17.     Top = 8
18.     Width = 73
19.     Height = 16
20.     Caption = 'active File'
21.     Font.Charset = DEFAULT_CHARSET
22.     Font.Color = clWindowText
23.     Font.Height = -13
24.     Font.Name = 'MS Sans Serif'
25.     Font.Style = [fsBold]
26.     ParentFont = False
27.   end
28.   object LabFileName: TLabel
29.     Left = 152
30.     Top = 8
31.     Width = 27
32.     Height = 16
33.     Caption = 'New'
34.     Font.Charset = ANSI_CHARSET
35.     Font.Color = clNavy
36.     Font.Height = -16
37.     Font.Name = 'Courier'
38.     Font.Style = []
39.     ParentFont = False
40.   end
41.   object LabSg0: TLabel
42.     Left = 32
43.     Top = 32
44.     Width = 108
45.     Height = 16
46.     Caption = 'active Segment'
47.     Font.Charset = DEFAULT_CHARSET
48.     Font.Color = clWindowText
49.     Font.Height = -13
50.     Font.Name = 'MS Sans Serif'
51.     Font.Style = [fsBold]
52.     ParentFont = False
53.   end
54.   object errlog: TMemo
55.     Left = 152
56.     Top = 64
57.     Width = 473
58.     Height = 273
59.     Font.Charset = ANSI_CHARSET
60.     Font.Color = clMaroon
61.     Font.Height = -12
62.     Font.Name = 'Courier New'
63.     Font.Style = []
64.     ParentFont = False
65.     ScrollBars = ssVertical
66.     TabOrder = 0
67.   end
68.   object comboSeg: TComboBox
69.     Left = 152
70.     Top = 32
71.     Width = 153
72.     Height = 24
73.     Font.Charset = ANSI_CHARSET
74.     Font.Color = clNavy
75.     Font.Height = -16
76.     Font.Name = 'Courier'
77.     Font.Style = []
78.     ItemHeight = 16
79.     ParentFont = False
80.     TabOrder = 1
81.     Text = 'none'
82.   end
83.   object butlatsh: TButton
84.     Left = 312
85.     Top = 32
86.     Width = 225
87.     Height = 25
88.     Caption = 'Show Lattice Expansion'
89.     Font.Charset = DEFAULT_CHARSET
90.     Font.Color = clWindowText
91.     Font.Height = -13
92.     Font.Name = 'MS Sans Serif'
93.     Font.Style = []
94.     ParentFont = False
95.     TabOrder = 2
96.   end
97.   object panstatus: TPanel
98.     Left = 8
99.     Top = 64
100.     Width = 137
101.     Height = 273
102.     BevelOuter = bvLowered
103.     Color = clHighlightText
104.     TabOrder = 3
105.     object labstflag: TLabel
106.       Left = 38
107.       Top = 22
108.       Width = 71
109.       Height = 13
110.       Caption = 'Status Flags'
111.       Font.Charset = DEFAULT_CHARSET
112.       Font.Color = clNavy
113.       Font.Height = -11
114.       Font.Name = 'MS Sans Serif'
115.       Font.Style = [fsBold]
116.       ParentFont = False
117.     end
118.     object labstelem: TLabel
119.       Left = 38
120.       Top = 46
121.       Width = 98
122.       Height = 13
123.       Caption = 'Special Elements'
124.       Font.Charset = DEFAULT_CHARSET
125.       Font.Color = clNavy
126.       Font.Height = -11
127.       Font.Name = 'MS Sans Serif'
128.       Font.Style = [fsBold]
129.       ParentFont = False
130.     end
131.     object labstdata: TLabel
132.       Left = 38
133.       Top = 78
134.       Width = 92
135.       Height = 13
136.       Caption = 'Calculated Data'
137.       Font.Charset = DEFAULT_CHARSET
138.       Font.Color = clNavy
139.       Font.Height = -11
140.       Font.Name = 'MS Sans Serif'
141.       Font.Style = [fsBold]
142.       ParentFont = False
143.     end
144.   end
145.   object MainMenu1: TMainMenu
146.     Left = 8
147.     Top = 40
148.     object mi_file: TMenuItem
149.       Caption = 'File'
150.       object fi_new: TMenuItem
151.         Caption = 'New'
152.       end
153.       object fi_open: TMenuItem
154.         Caption = 'Open...'
155.       end
156.       object fi_last: TMenuItem
157.         Caption = 'Last Used'
158.       end
159.       object fi_save: TMenuItem
160.         Caption = 'Save'
161.       end
162.       object fi_svas: TMenuItem
163.         Caption = 'Save as...'
164.       end
165.       object fi_expo: TMenuItem
166.         Caption = 'Export to .'
167.         object ex_tracy2: TMenuItem
168.           Caption = 'Tracy-2'
169.         end
170.         object ex_tracy3: TMenuItem
171.           Caption = 'Tracy-3'
172.         end
173.         object ex_elegant: TMenuItem
174.           Caption = 'Elegant'
175.         end
176.         object ex_madx: TMenuItem
177.           Caption = 'MAD-X'
178.         end
179.         object ex_bmad: TMenuItem
180.           Caption = 'BMAD'
181.         end
182.       end
183.       object N1: TMenuItem
184.         Caption = '-'
185.       end
186.       object fi_exit: TMenuItem
187.         Caption = 'Exit'
188.       end
189.     end
190.     object mi_edit: TMenuItem
191.       Caption = 'Edit'
192.       object ed_text: TMenuItem
193.         Caption = 'Text Editor'
194.       end
195.       object ed_oped: TMenuItem
196.         Caption = 'OPA Editor'
197.       end
198.     end
199.     object mi_desi: TMenuItem
200.       Caption = 'Design'
201.       object ds_opti: TMenuItem
202.         Caption = 'Linear Optics'
203.         Enabled = False
204.       end
205.       object ds_dppo: TMenuItem
206.         Caption = 'Off-momentum Optics'
207.         Enabled = False
208.       end
209.       object ds_sext: TMenuItem
210.         Caption = 'Non-linear Dynamics'
211.         Enabled = False
212.       end
213.       object ds_lgbo: TMenuItem
214.         Caption = 'LGB Optimizer'
215.       end
216.       object ds_orbc: TMenuItem
217.         Caption = 'Orbit Correction'
218.         Enabled = False
219.       end
220.       object ds_injc: TMenuItem
221.         Caption = 'Injection Bumps'
222.         Enabled = False
223.       end
224.       object ds_rfbu: TMenuItem
225.         Caption = 'RF Bucket Viewer'
226.       end
227.     end
228.     object mi_trac: TMenuItem
229.       Caption = 'Tracking'
230.       object tr_phsp: TMenuItem
231.         Caption = 'Phase Space'
232.         Enabled = False
233.       end
234.       object tr_dyna: TMenuItem
235.         Caption = 'Dynamic Aperture'
236.         Enabled = False
237.       end
238.       object tr_ttau: TMenuItem
239.         Caption = 'Touschek Lifetime'
240.         Enabled = False
241.       end
242.     end
243.     object mi_extr: TMenuItem
244.       Caption = 'Extra'
245.       object tm_geo: TMenuItem
246.         Caption = 'Geometry Layout'
247.         Enabled = False
248.       end
249.       object tm_cur: TMenuItem
250.         Caption = 'Magnet Currents '
251.         Enabled = False
252.       end
253.       object tm_test: TMenuItem
254.         Caption = '(Test)'
255.       end
256.     end
257.   end
258.   object OpenDialog1: TOpenDialog
259.     Filter =
260.       'OPA File (*.opa)|*.opa|TRACY Lattice File (*.lat)|*.lat|MAD Inpu' +
261.       't File (*.mad)|*.mad'
262.     Title = 'select lattice file'
263.     Left = 8
264.     Top = 24
265.   end
266.   object SaveDialog1: TSaveDialog
267.     DefaultExt = 'opa'
268.     Left = 8
269.     Top = 8
270.   end
271. end
272.  

opa.lpi

Code: XML  [Select][+][-]

1. <?xml version="1.0" encoding="UTF-8"?>
2. <CONFIG>
3.   <ProjectOptions>
4.     <Version Value="11"/>
5.     <PathDelim Value="\"/>
6.     <General>
7.       <Flags>
8.         <MainUnitHasUsesSectionForAllUnits Value="False"/>
9.         <MainUnitHasCreateFormStatements Value="False"/>
10.         <MainUnitHasTitleStatement Value="False"/>
11.         <MainUnitHasScaledStatement Value="False"/>
12.       </Flags>
13.       <SessionStorage Value="InProjectDir"/>
14.       <MainUnit Value="0"/>
15.       <Title Value="opa"/>
16.       <UseAppBundle Value="False"/>
17.       <ResourceType Value="res"/>
18.     </General>
19.     <BuildModes Count="1">
20.       <Item1 Name="Default" Default="True"/>
21.     </BuildModes>
22.     <PublishOptions>
23.       <Version Value="2"/>
24.       <UseFileFilters Value="True"/>
25.     </PublishOptions>
26.     <RunParams>
27.       <FormatVersion Value="2"/>
28.       <Modes Count="0"/>
29.     </RunParams>
30.     <RequiredPackages Count="2">
31.       <Item1>
32.         <PackageName Value="Printer4Lazarus"/>
33.       </Item1>
34.       <Item2>
35.         <PackageName Value="LCL"/>
36.       </Item2>
37.     </RequiredPackages>
38.     <Units Count="2">
39.       <Unit0>
40.         <Filename Value="opa.lpr"/>
41.         <IsPartOfProject Value="True"/>
42.       </Unit0>
43.       <Unit1>
44.         <Filename Value="opamenu.pas"/>
45.         <IsPartOfProject Value="True"/>
46.         <HasResources Value="True"/>
47.       </Unit1>
48.     </Units>
49.   </ProjectOptions>
50.   <CompilerOptions>
51.     <Version Value="11"/>
52.     <PathDelim Value="\"/>
53.     <SearchPaths>
54.       <IncludeFiles Value="..\..\com"/>
55.       <UnitOutputDirectory Value="lib\$(TargetCPU)-$(TargetOS)"/>
56.     </SearchPaths>
57.     <Parsing>
58.       <SyntaxOptions>
59.         <SyntaxMode Value="delphi"/>
60.       </SyntaxOptions>
61.     </Parsing>
62.     <Linking>
63.       <Options>
64.         <Win32>
65.           <GraphicApplication Value="True"/>
66.         </Win32>
67.       </Options>
68.     </Linking>
69.   </CompilerOptions>
70.   <Debugging>
71.     <Exceptions Count="4">
72.       <Item1>
73.         <Name Value="EAbort"/>
74.       </Item1>
75.       <Item2>
76.         <Name Value="ECodetoolError"/>
77.       </Item2>
78.       <Item3>
79.         <Name Value="EFOpenError"/>
80.       </Item3>
81.       <Item4>
82.         <Name Value="EStringListError"/>
83.       </Item4>
84.     </Exceptions>
85.   </Debugging>
86. </CONFIG>
87.  

[winni]

Hi!

If there are files which can't be changed by the IDE there is a big chance that readonly is set to one ore more files. Instructions here:

https://smallbusiness.chron.com/change-read-only-files-folders-54559.html

Winni

[lucamar]

It may not have anything to do with your problem but note that calling your form Menu (hence its class TMenu) is exceedingly bad. There is already a class TMenu (ancestor of all menus) in the LCL and calling your form that may lead to unexpected and difficult to debug bugs.

If I may be so bold, I think you should call your form something else like, say, MenuFrm (class TMenuFrm).

In general, try to avoid "reusing" class names which already exist unless you know exactly what you're doing (for example, creating an interposed class)

[JuhaManninen]

If there are files which can't be changed by the IDE there is a big chance that readonly is set to one ore more files. Instructions here:

Please read his first post. He switched between form/unit view. It is not related to readonly files. Besides readonly files do not crash the IDE.

@perAspera, after fixing the obvious potential problem pointed by lucamar, please compress your example project sources into one zip file (or similar) and upload it here. It will be easier to extract and test. No binaries, just sources.
Hint, there is also a nice Project -> Publish Project ... feature.

[wp]

I pasted your code into a new project/form and confirm the crash. lucamar is right, naming the form a TMenu was a bad idea, it probably causes all the trouble. Did Delphi accept this?

I opened the pas file in an external editor and changed the form type to TMenuForm and its instance to MenuForm:

Code: Pascal  [Select][+][-]

1. type
2.   TMenuForm = class(TForm)  
3.   ...
4.   end;
5.  
6. var
7.   MenuForm: TMenuForm;

(Of course in your real form, you must also change the class names at each method implementation, too).

Next is the lfm file - the first line should be

Code: Pascal  [Select][+][-]

1. object MenuForm: TMenuForm  

And the lpr file. Change the Application.CreateForm to

Code: Pascal  [Select][+][-]

1.   Application.CreateForm(TMenuForm, MenuForm);

I am not quite sure if I remember correctly, but I think after these changes I could load the form into Lazarus, but there was still a SIGFPE runtime error. I am not sure what finally solved it, but I think it was the double-click on the TMainMenu component which opened the menu editor and forced the menu structure to be rewritten. Now the code compiles and runs.

A wish for the next post: You would help us if you'd avoid pasting full code into the post directly; it would be much better we had the source files directly (this would have allowed me to download the original project again, do the changes and find out how EXACTLY is solved the issue; but I did not want to repeat the hassle of pasting the code into empty Lazarus files again...). In order to upload a project, pack the *.pas, *.lfm, *.lpi and *.lpr files (plus any data files needed) into a common zip file. Below the forum editor box  you find "Attachments and other options" where you can upload the zip file. Do not include compiler-generated files, mainly the exe, in the zip, otherwise the file might exceed the forum upload limit for 250kB.

[perAspera]

Thank you so much for your kind help!
I'm impressed how you engaged yourself in my problem and, special thanks to @wp that you solved it for me. I implemented the changes and now everything is fine - I even didn't get a runtime error, perhaps in the shortened version I posted something was missing.

It seems Delphi, at least the old version 5, is more relaxed with regard to special words. I will pay attention to that.

And thanks for the hint on how to post code.