From 8bfb255c96be6fa65514c5b46373a1e6a1f019f1 Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Sun, 1 Nov 2020 23:46:09 +0000
Subject: [PATCH] Put a warning when routing can't start due to DRC violation.

Fixes https://gitlab.com/kicad/code/kicad/issues/4975
---
 pcbnew/router/pns_node.h     |  9 +++++----
 pcbnew/router/pns_router.cpp | 21 ++++++++++++++++++---
 pcbnew/router/pns_router.h   |  6 +-----
 3 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/pcbnew/router/pns_node.h b/pcbnew/router/pns_node.h
index ba683ed763..1df13c3e7f 100644
--- a/pcbnew/router/pns_node.h
+++ b/pcbnew/router/pns_node.h
@@ -231,11 +231,12 @@ public:
                         bool         aDifferentNetsOnly = true,
                         int          aForceClearance = -1 );
 
-    int QueryJoints( const BOX2I& aBox, std::vector<JOINT*> & aJoints, int aLayerMask = -1, int aKindMask = ITEM::ANY_T);
+    int QueryJoints( const BOX2I&         aBox,
+                     std::vector<JOINT*>& aJoints,
+                     int                  aLayerMask = -1,
+                     int                  aKindMask = ITEM::ANY_T);
 
-    int QueryColliding( const ITEM* aItem,
-                         OBSTACLE_VISITOR& aVisitor
-                      );
+    int QueryColliding( const ITEM* aItem, OBSTACLE_VISITOR& aVisitor );
 
     /**
      * Function NearestObstacle()
diff --git a/pcbnew/router/pns_router.cpp b/pcbnew/router/pns_router.cpp
index b770d7f60f..2282e2d6de 100644
--- a/pcbnew/router/pns_router.cpp
+++ b/pcbnew/router/pns_router.cpp
@@ -170,12 +170,12 @@ bool ROUTER::StartDragging( const VECTOR2I& aP, ITEM_SET aStartItems, int aDragM
     return true;
 }
 
-bool ROUTER::isStartingPointRoutable( const VECTOR2I& aWhere, int aLayer )
+bool ROUTER::isStartingPointRoutable( const VECTOR2I& aWhere, ITEM* aStartItem, int aLayer )
 {
     if( Settings().CanViolateDRC() && Settings().Mode() == RM_MarkObstacles )
         return true;
 
-    auto candidates = QueryHoverItems( aWhere );
+    ITEM_SET candidates = QueryHoverItems( aWhere );
 
     for( ITEM* item : candidates.Items() )
     {
@@ -183,12 +183,27 @@ bool ROUTER::isStartingPointRoutable( const VECTOR2I& aWhere, int aLayer )
             return false;
     }
 
+    if( m_mode == PNS_MODE_ROUTE_SINGLE )
+    {
+        VECTOR2I startPoint = aStartItem->Anchor( 0 );
+        SEGMENT  dummyStartSeg( SEG( startPoint, startPoint ), aStartItem->Net() );
+
+        dummyStartSeg.SetWidth( m_sizes.TrackWidth() );
+
+        if( m_world->CheckColliding( &dummyStartSeg, ITEM::ANY_T ) )
+            return false;
+    }
+    else if( m_mode == PNS_MODE_ROUTE_DIFF_PAIR )
+    {
+        // TODO
+    }
+
     return true;
 }
 
 bool ROUTER::StartRouting( const VECTOR2I& aP, ITEM* aStartItem, int aLayer )
 {   
-    if( ! isStartingPointRoutable( aP, aLayer ) )
+    if( ! isStartingPointRoutable( aP, aStartItem, aLayer ) )
     {
         SetFailureReason( _( "The routing start point violates DRC." ) );
         return false;
diff --git a/pcbnew/router/pns_router.h b/pcbnew/router/pns_router.h
index d139b95b54..80b4e811d8 100644
--- a/pcbnew/router/pns_router.h
+++ b/pcbnew/router/pns_router.h
@@ -152,8 +152,6 @@ public:
     void CommitRouting();
     void StopRouting();
 
-    int GetClearance( const ITEM* aA, const ITEM* aB ) const;
-
     NODE* GetWorld() const
     {
         return m_world.get();
@@ -161,8 +159,6 @@ public:
 
     void FlipPosture();
 
-    void DisplayItem( const ITEM* aItem, int aColor = -1, int aClearance = -1, bool aEdit = false );
-    void DeleteTraces( ITEM* aStartItem, bool aWholeTrack );
     void SwitchLayer( int layer );
 
     void ToggleViaPlacement();
@@ -262,7 +258,7 @@ private:
     void highlightCurrent( bool enabled );
 
     void markViolations( NODE* aNode, ITEM_SET& aCurrent, NODE::ITEM_VECTOR& aRemoved );
-    bool isStartingPointRoutable( const VECTOR2I& aWhere, int aLayer );
+    bool isStartingPointRoutable( const VECTOR2I& aWhere, ITEM* aItem, int aLayer );
 
     VECTOR2I m_currentEnd;
     RouterState m_state;