From 9cb6df9c383c511c04496ffc1abe31c96ec4e478 Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Tue, 13 Sep 2022 13:27:39 +0100
Subject: [PATCH] Don't crash on empty SHAPE_LINE_CHAINs.

Fixes https://gitlab.com/kicad/code/kicad/issues/12407

(cherry picked from commit fc74de81fb8279911c87aa352bc0b9a375c8cb90)
---
 libs/kimath/src/geometry/shape_line_chain.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/libs/kimath/src/geometry/shape_line_chain.cpp b/libs/kimath/src/geometry/shape_line_chain.cpp
index 723ee2391a..5c225ac881 100644
--- a/libs/kimath/src/geometry/shape_line_chain.cpp
+++ b/libs/kimath/src/geometry/shape_line_chain.cpp
@@ -1791,6 +1791,12 @@ SHAPE_LINE_CHAIN& SHAPE_LINE_CHAIN::Simplify( bool aRemoveColinear )
 const VECTOR2I SHAPE_LINE_CHAIN::NearestPoint( const VECTOR2I& aP,
                                                bool aAllowInternalShapePoints ) const
 {
+    if( PointCount() == 0 )
+    {
+        // The only right answer here is "don't crash".
+        return { 0, 0 };
+    }
+
     int min_d = INT_MAX;
     int nearest = 0;
 
@@ -1842,6 +1848,12 @@ const VECTOR2I SHAPE_LINE_CHAIN::NearestPoint( const VECTOR2I& aP,
 
 const VECTOR2I SHAPE_LINE_CHAIN::NearestPoint( const SEG& aSeg, int& dist ) const
 {
+    if( PointCount() == 0 )
+    {
+        // The only right answer here is "don't crash".
+        return { 0, 0 };
+    }
+
     int nearest = 0;
 
     dist = INT_MAX;