From 446a9ca866489bf1af54488db075d8d8874dd281 Mon Sep 17 00:00:00 2001
From: jean-pierre charras <jp.charras@wanadoo.fr>
Date: Thu, 24 Sep 2020 11:05:56 +0200
Subject: [PATCH] Round-rect pads: use a circle to draw degenerated shapes. A
 degenerated shape is a round-rect pads with same X and Y size, and a radius
 very near 50% of the size.

Fixes #5768
https://gitlab.com/kicad/code/kicad/issues/5768
---
 pcbnew/class_pad.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pcbnew/class_pad.cpp b/pcbnew/class_pad.cpp
index 5227cc31de..a8e76a1ad2 100644
--- a/pcbnew/class_pad.cpp
+++ b/pcbnew/class_pad.cpp
@@ -347,7 +347,19 @@ void D_PAD::BuildEffectiveShapes( PCB_LAYER_ID aLayer ) const
         wxSize  trap_delta( 0, 0 );
 
         if( effectiveShape == PAD_SHAPE_ROUNDRECT )
+        {
             half_size -= wxPoint( r, r );
+
+            // Avoid degenerated shapes (0 length segments) that always create issues
+            // For roundrect pad very near a circle, use only a circle
+            const int min_len = Millimeter2iu( 0.0001);
+
+            if( half_size.x < min_len && half_size.y < min_len )
+            {
+                add( new SHAPE_CIRCLE( shapePos, r ) );
+                break;
+            }
+        }
         else if( effectiveShape == PAD_SHAPE_TRAPEZOID )
             trap_delta = m_deltaSize / 2;