Created attachment 115725 [details]
Source code for the WidgedListCrash program.

SUMMARY
When dragging and dropping items in a QListWidget that have an associated icon,
the list gets corrupted, which subsequently results in a crash. This Qt
problem has been reported to happen only on the KDE platform and not other
platforms such as Gnome. It is also reported that it only happens on Qt5, and
not on Qt4. I have posted the bug here because it is reported to occur only
on KDE.

All of my computers are running Plasma5 and Qt5, so I cannot attest to the
assertions about Qt4 and Gnome.


STEPS TO REPRODUCE
1. Compile WidgetListCrash program
2. Open terminal window
3. Run WidgetListCrash
4. Drag a list item that has an icon with it to another location in that
list or the other list.

OBSERVED RESULT

The program crashes with the following errors:

Trying to construct an instance of an invalid type, type id: 6553705
Trying to construct an instance of an invalid type, type id: 788558336
Trying to construct an instance of an invalid type, type id: 524358
terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
Aborted (core dumped)


EXPECTED RESULT

The dragged item should be moved to the drop location in the list.


SOFTWARE VERSIONS
(available in About System)
Mageia 6
KDE Plasma Version:  5.12.2
KDE Frameworks Version: 5.42.0
Qt Version: 5.9.4

Mint 18.1
KDE Plasma Version:  5.8.9
KDE Frameworks Version: 5.36.0
Qt Version: 5.6.1


ADDITIONAL INFORMATION

The problem can be easily replicated using a small program, which can be found here:

https://gitlab.com/bugpocs/WidgetListCrash

and in the attachment. There is a QtCreator project file (.pro)

One system is running Mageia 6,, with the following system paramaters:

System:    Host: mageia6 Kernel: 4.14.70-desktop-2.mga6 x86_64 (64 bit) Desktop: KDE Plasma 5.12.2
           Distro: Mageia 6 mga6
Machine:   Device: desktop Mobo: ASUSTeK model: P5G41T-M LX PLUS v: Rev X.0x BIOS: American Megatrends v: 0502 date: 10/21/2011
CPU:       Dual core Intel Core2 Duo E7300 (-MCP-) speed/max: 1617/1927 MHz
Graphics:  Card: NVIDIA G94 [GeForce 9600 GT]
           Display Server: Mageia X.org 119.5 drivers: v4l,nouveau Resolution: 1680x1050@59.95hz
           GLX Renderer: NV94 GLX Version: 3.0 Mesa 17.3.9


When I run the WidgetListCrash program on Mageia6 and attempt to move one of the list items
that has an icon associated with it, the program crashes with the following output:

$ ./WidgetListCrash 
Trying to construct an instance of an invalid type, type id: 6553705
Trying to construct an instance of an invalid type, type id: 788558336
Trying to construct an instance of an invalid type, type id: 524358
terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
Aborted (core dumped)
[poobah@mageia6 WidgetListCrash-master]$


I can reproduce this bug on my Mint 18.1 system as well, but with different
symptoms. Here are the system parameters of my Mint system.


System:    Host: LinuxMain Kernel: 4.4.0-137-generic x86_64 (64 bit) Desktop: KDE Plasma 5.8.9
           Distro: Linux Mint 18.1 Serena
Machine:   System: ASUS product: All Series
           Mobo: ASUSTeK model: Z97-A-USB31 v: Rev 1.xx
           Bios: American Megatrends v: 2501 date: 06/24/2015
CPU:       Quad core Intel Core i5-4590 (-MCP-) speed/max: 3282/3700 MHz
Graphics:  Card: NVIDIA GM107 [GeForce GTX 750 Ti]
           Display Server: X.Org 1.18.4 drivers: nvidia (unloaded: fbdev,vesa,nouveau)
           Resolution: 1920x1080@60.00hz, 1920x1080@60.00hz
           GLX Renderer: GeForce GTX 750 Ti/PCIe/SSE2 GLX Version: 4.5.0 NVIDIA 384.130


When I run the WidgetListCrash program on Mint and attempt to move one of the list items
that has an icon associated with it, the list gets corrupted, leaving blank
spaces between the list items. On subsequent attempts to move the item, the
program crashes with the following output:

$ ./WidgetListCrash
Trying to construct an instance of an invalid type, type id: 6553705
Trying to construct an instance of an invalid type, type id: 788558336
Trying to construct an instance of an invalid type, type id: 524358
Trying to construct an instance of an invalid type, type id: 6553705
Trying to construct an instance of an invalid type, type id: 788558336
Trying to construct an instance of an invalid type, type id: 524358
Segmentation fault