[Kstars-devel] Heisenbug leading to crash at Legend::setAlpha()

[Akarsh Simha]

So I'm encountering a crash when I try to "Export Sky Image" and then
go to "Preview" to preview the legend. I'm pretty sure I introduced
this sometime in January (see git log on imageexporter.cpp), but I
don't know what's causing it, and how I may be able to fix it.

Here's the backtrace from the crash. In my experience -- it has
occurred at random. Only today has it been consistently crashing
(because I actually want to get some charts made).
http://paste.kde.org/715580/

I tried to study the bug using gdb, but it's a Heisenbug -- most of
the times when I try to study it, it disappears. I was able to track
down very close once under gdb.

In this method:
void ImageExporter::setLegendAlpha( int alpha )

When I tried using gdb to print m_Legend after the asserts, for
example, I got an error saying it could not access that memory
location. I don't see a place where the pointer has been toyed around
with, so I don't see how the pointer can't point to something
sensible. Here's the relevant interaction with gdb:
http://paste.kde.org/715586/

Any pointers will be greatly appreciated!

Regards
Akarsh