[Bug] Broken vector topology crashes wxGUI

[neteler]

Describe the bug

Opening a vector map (polygons) with broken topology (due to previous crash), the entire wxGUI shuts down:

Coor file of vector map
<high_low_suitable_Europe@figures> is larger
than it should be (180 bytes excess)
Traceback (most recent call last):
  File "/home/mneteler/software/grass78_git/dist.x86_64-pc-
linux-gnu/gui/wxpython/mapwin/buffered.py", line 593, in
OnPaint

self.pdcVector.DrawToDCClipped(gcdc, rgn)
wx._core
.
wxAssertionError
:
C++ assertion "n > 1" failed at
../src/common/graphcmn.cpp(742) in StrokeLines():
Traceback (most recent call last):
  File "/home/mneteler/software/grass78_git/dist.x86_64-pc-
linux-gnu/gui/wxpython/mapwin/buffered.py", line 593, in
OnPaint

self.pdcVector.DrawToDCClipped(gcdc, rgn)
wx._core
.
wxAssertionError
:
C++ assertion "n > 1" failed at
../src/common/graphcmn.cpp(742) in StrokeLines():
Traceback (most recent call last):
[...]

It seems to be in a loop, repeating the same Traceback multiple times (may also be due to zooming attempts).

To Reproduce

Hard to reproduce. It usually silently crashes.

System description (please complete the following information):

Linux Fedora 31

g.version -rge
version=7.8.3dev
date=2020
revision=ecc6e6f79
build_date=2020-04-04
build_platform=x86_64-pc-linux-gnu
build_off_t_size=8
libgis_revision=340c2a4a0
libgis_date="Thu Apr 2 13:03:21 2020 +0200"
proj=5.2.0
gdal=2.3.2
geos=3.7.1
sqlite=3.30.0

Screenshot

[neteler]

Confirmed also for master.

[petrasovaa]

I can't reproduce it, which is not a big surprise. Maybe it happens with a particular vector you could share?

[neteler]

I have stored the vector map here as a "pack" file (EPSG 4326):

https://data.neteler.org/tmp/high_low_suitable_Europe.pack

[tmszi]

I confirm this bug (tested with santana3a_high_low_suitable_Europe vector map layer)

Error message (star editting):

Traceback (most recent call last):
  File "/usr/lib64/grass79/gui/wxpython/mapwin/buffered.py",
line 593, in OnPaint

self.pdcVector.DrawToDCClipped(gcdc, rgn)
wx._core
.
wxAssertionError
:
C++ assertion "n > 1" failed at /var/tmp/portage/x11-libs/wx
GTK-3.0.4-r302/work/wxWidgets-3.0.4/src/common/graphcmn.cpp(
742) in StrokeLines():

[neteler]

Still the case in current master:

GRASS version: 7.9.dev                                                          
Code revision: 64527a73f                                                        
Build date: 2020-08-06                                                          
Build platform: x86_64-pc-linux-gnu                                             
GDAL: 3.0.4                                                                     
PROJ: 6.3.2                                                                     
GEOS: 3.8.1                                                                     
SQLite: 3.32.3                                                                  
Python: 3.8.5                                                                   
wxPython: 4.0.7                                                                 
Platform: Linux-5.6.16-300.fc32.x86_64-x86_64-with-glibc2.2.5

[tmszi]

Additional info:

If I zoom into santana3a_high_low_suitable_Europe vector map layer, and start editing after that, editing work correctly. If I zoom out or move/pan to problematic part of vector topology during editing I got same error message as mentioned above and render maps stop (same screenshot).

v.build -e map=santana3a_high_low_suitable_Europe

Building topology for vector map <santana3a_high_low_suitable_Europe@PERMANENT>...
Registering primitives...
Building areas...
 100%
Attaching islands...
 100%
Attaching centroids...
 100%
WARNING: Number of incorrect boundaries: 66
WARNING: Number of centroids outside area: 1
Checking for topological errors...
WARNING: Number of boundaries of length zero: 2
ERROR: Intersection with points is not yet supported

Problematic is WARNING: Number of boundaries of length zero: 2.

After clean vector map, editing work correctly.

v.clean input=santana3a_high_low_suitable_Europe@PERMANENT output=santana3a_high_low_suitable_Europe_clean type=line,boundary tool=rmline thres=0.00

[neteler]

Great, PR #911 solves it nicely:

... "Yes" leads to:

Thanks, @tmszi !

[petrasovaa]

Fixed in #1989, it is in main and 8.0 branch now.