bugGNU Octave - Bugs: bug #59677, Debug pointer doesn't move with...


bug #59677: Debug pointer doesn't move with debug steps during 'nested' debugging

Submitter:  Philip Nienhuis <philipnienhuis>
Submitted:  Sun 13 Dec 2020 10:33:05 PM UTC
Category:  Interpreter Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Confirmed Assigned to:  None
Originator Name:  Philip Nienhuis Open/Closed:  * Open
Release:  * dev Operating System:  * Any
* Mandatory Fields

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Wed 03 Feb 2021 07:18:19 PM UTC, comment #3: 

I see the problem but I'm not sure how to fix it.  We may need to rethink the way code locations are stored in the call stack during code evaluation.

John W. Eaton <jwe>
Project Administrator
Mon 21 Dec 2020 08:42:05 AM UTC, comment #2: 

Initially I figured it was a mere cosmetic issue.
With your findings I now think it probably still is, but with a deeper cause :-)

Category => "Interpreter"

Philip Nienhuis <philipnienhuis>
Project Member
Sun 20 Dec 2020 07:58:56 PM UTC, comment #1: 

Confirmed on Linux. But this does not seem to be an issue of the GUI. When you enable the option "Print debug location in command window ..." (preferences, tab "Command") the location printed in the command window also repeatedly displays "stopped in fb at line 2".

You can also try this in the cli version:

dbstop fa 2
dbstop fb 2

Torsten Lilge <ttl>
Project Member
Sun 13 Dec 2020 10:33:05 PM UTC, original submission:  

First off, I don't know if this is a real bug; but what I see is surely counter-intuitively.
Steps to reproduce, all in the GUI:

Define two functions funca and funcb, more or less as follows:

function a = funca ()
  a = 1;
  a = 2;
  a = funcb ();
  a = 4;

function b = funcb ()
  b = 1;
  b = 2;
  b = 3;
  b = 4;

In both functions, add a breakpoints at L.2.

Then, type 'funca'
=> execution stops in funca at L2, fine.

Now, in funca.m select L.4 'a = funcb ();' and press F9
=> executions stops in funcb at L2, and the prompt changes to '[1]debug>', fine.

Then, press the "Step" button repeatedly.
The 'debug pointer' (yellow arrow) stays at L.2 (that is the bug) but in the Workspace pane the value of 'b' is increased until funcb is finished (which AFAIU is correct).
So the debug pointer doesn't follow the "active" line in funcb. IOW, a sort of "blind" debugging stepping.

Going on clicking the 'Step' button, execution is picked up again in funca and the debug pointer correctly follows the "active" lines, also in funcb.
I do have the "Always show debug breakpoints and pointers (opens related file if closed)" set.

Philip Nienhuis <philipnienhuis>
Project Member


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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-02-03 jwe StatusNone Confirmed
        Release6.1.0 dev
    2020-12-21 philipnienhuis CategoryGUI Interpreter
    2020-12-20 ttl Operating SystemMicrosoft Windows Any

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