Differential pair: infinite loop in makeGapVector

[Jean-Samuel Reynaud]

There is an infinite loop in differential pair routing.
How to reproduce this:

Start the differential pair routing from a square PAD (width == height, not from a rectangular). In this case there is the following flow:
- diagFanDistance become "0" at pcbnew/router/pns_diff_pair.c:468
- dir become a zero length vector at pcbnew/router/pns_diff_pair.c:504
- makeGapVector try to increase the size of a zero len vector (pcbnew/router/pns_diff_pair.c:506 then pcbnew/router/pns_diff_pair.c:417).

This result on an infinite loop...

It occur also when you start from a rectangular and you try to join a square pad... But more difficult to reproduce.

Not sure... but probably commit 0a55d8e0533929ca66036be51dd90bdbefe50f1b introduce this error...

Application: pcbnew
Version: no-vcs-found-1724f90~58~ubuntu16.04.1, release build
Libraries: wxWidgets 3.0.2
           libcurl/7.47.0 OpenSSL/1.0.2g zlib/1.2.8 libidn/1.32 librtmp/2.3
Platform: Linux 4.4.0-81-generic x86_64, 64 bit, Little endian, wxGTK
- Build Info -
wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8)
Boost: 1.58.0
Curl: 7.47.0
KiCad - Compiler: GCC 5.4.0 with C++ ABI 1009
        Settings: USE_WX_GRAPHICS_CONTEXT=OFF
                  USE_WX_OVERLAY=OFF
                  KICAD_SCRIPTING=ON
                  KICAD_SCRIPTING_MODULES=ON
                  KICAD_SCRIPTING_WXPYTHON=ON
                  KICAD_SCRIPTING_ACTION_MENU=ON
                  BUILD_GITHUB_PLUGIN=ON
                  KICAD_USE_OCE=ON

[Jean-Samuel Reynaud (js-reynaud)]

Attached patch propose a solution to fix this bug.

[Tomasz Wlostowski (twlostow)]

Dear JS,

Committed, thanks for fixing the bug!

Tom

[KiCad Janitor (kicad-janitor)]

Fixed in revision 885a4c1bc597fefd29e39634d7f342901b3d3958
https://git.launchpad.net/kicad/patch/?id=885a4c1bc597fefd29e39634d7f342901b3d3958