Crash skewing strokeless line

[Duarte Ramos]

Inkscape 0.91 crashes on Windows 10 Home 64bits while skewing a vertical or horizontal line with no stroke.

I was trying to change rotation center of a vertical line which is hard has mentioned in bug #1262448 https://bugs.launchpad.net/inkscape/+bug/1262448 and accidental skewed a line which happened to have no stroke causing inkscape to crash.

Steps to reproduce:
# Create a new path with bezier tool tool
#Pick on any point
# Use CTRL to create perfectly vertical or horizontal line and create only a second node
# Press enter to finish
# With selection tool select previously created line
# Click again to change to rotation mode (make sure it still as a stroke or this will be impossible to achieve)
# Now go to fill panel and remove the stroke
# Try to skew line along Y axis for vertical lines or X axis for horizontal one
# Inkscape will 'gracefully crash' saving a recovery file.

[su_v (suv-lp)]

On OS X 10.7.5:
- crash not reproduced with Inkscape 0.48.5 r10040
- crash reproduced with Inkscape 0.91 r13725
- crash not reproduced with Inkscape 0.91+devel r14451
(the result however is a single-node path at the SVG origin, with d="M 0,0 V 0")

Based on tests with archived builds:
- reproduced with rev <= 14224,
- not reproduced with rev >= 14228;
the changes with the 2geom update in rev 14226 seem to prevent the crash:
https://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/14226
Whether or not the result is to be considered expected and/or valid needs to be determined elsewhere.

Attached is a full backtrace of a debug build from the stable release branch (Inkscape 0.91 r13844 custom (Oct 24 2015))

[Duarte Ramos (duarte-framos)]

Thanks for the fix