Calculate DC bias with Sweep is broken

[in3otd]

This schematic using a Sweep with a DC simulation crashes the Qucs GUI when running Calculate DC bias (F8) . Simpler schematics often run, but the small dialog allowing to select the sweep run to use for showing the DC bias is not shown. Was apparently broken also in 0.0.18 (??).

[nvdl]

In "qucs.cpp":

SweepDialog Dia = new SweepDialog((Schematic)sim->DocWidget);

is causing the fault.

I checked and "sim->DocWidget" is not NULL.

"SweepDialog::SweepDialog(Schematic *Doc_)" seems to cause this.

[in3otd]

yes, I saw the gdbbacktrace... I was a bit puzzled since the only recent changes are 0a2f1a7166558281065e391c78a00e2e9f8346b5 and a09e00cb726544dfa0e2a1cff44c31485b2b9096 ; moreover it seems to crash already on 0.0.18...

[nvdl]

Will give it a try later.

What about: "delete pGraph;" line?

moreover it seems to crash already on 0.0.18... Same here.

In my fork, it works sometimes as there is a visible dock showing a warning. Looks like it has something to do with the schematic (viewport) in focus.

[nvdl]

Another crash example:

No idea if something is wrong in the schematic or if there is a lurking bug.

https://gist.github.com/nvdl/5ebe56ddebba5986ba95

[smile5]

With qucs 0.0.18, it crash with the two schematics.

If that can help: But if in the first "dc_bias_crash.sch" i f you rename the parameter, from "Vin" to another name, it doesn't crash... For the second, if you add a label, and if you modify the sweep param from "R4" to "R_var" modifying also the R4 value, don't forget to save, all goes well, but if you retry, to launch calculate dc bias it crash.

For me gdb on my fork, report SIGSEV in sweepdialog.cpp at line 140 or 49, it depend some time the small dialog open sometime not.

[nvdl]

But if in the first "dc_bias_crash.sch" i f you rename the parameter, from "Vin" to another name, it doesn't crash...

I renamed it to "abc" and it still crashes. I realized that I was sweeping a name and not a variable.

[smile5]

I retry, redownloaded example, modify the parameter value to "abc", save the file, and press F8, and don't crash with version 0.0.18, but the small window to choose the DC point not appear all the time, only the first time...

[nvdl]

OK, I might have again missed something. Can you check the pull request above? It fixes stuff on my side.

[guitorri]

This is the relevant part of the crash report I get with the first schematic:

0   qucs                            0x000000010ca7c097 mySpinBox::textFromValue(int) const + 71 (sweepdialog.cpp:49)
1   QtGui                           0x000000010d1d5bfa QSpinBoxPrivate::textFromValue(QVariant const&) const + 58
2   QtGui                           0x000000010d13bb81 QAbstractSpinBoxPrivate::updateEdit() + 273
3   QtGui                           0x000000010d1d6194 QSpinBox::setSingleStep(int) + 68
4   qucs                            0x000000010ca7bfca mySpinBox::mySpinBox(int, int, int, double*, QWidget*) + 122 (sweepdialog.cpp:37)
5   qucs                            0x000000010ca7c047 mySpinBox::mySpinBox(int, int, int, double*, QWidget*) + 55 (sweepdialog.cpp:42)
6   qucs                            0x000000010ca7c624 SweepDialog::SweepDialog(Schematic*) + 1108 (sweepdialog.cpp:101)
7   qucs                            0x000000010ca7d5ad SweepDialog::SweepDialog(Schematic*) + 29 (sweepdialog.cpp:114)
8   qucs                            0x000000010c63c69e QucsApp::slotAfterSimulation(int, SimMessage*) + 254 (qucs.cpp:2058)

[guitorri]

@nvdl your pull request seems to fix the crash. I left some comments on the PR.

[guitorri]

This passing around of pointers is hurting my brain... has anyone looked at it?

[guitorri]

Another fix attempt and more discussion in PR #282.