Allow free pad usage in router.

Fixes https://gitlab.com/kicad/code/kicad/issues/11730

pcbnew/router/pns_item.cpp

@@ -51,6 +51,10 @@ bool ITEM::collideSimple( const ITEM* aOther, const NODE* aNode, bool aDifferent
     if( aDifferentNetsOnly && m_net == aOther->m_net && m_net >= 0 && aOther->m_net >= 0 )
         return false;
 
+    // a pad associated with a "free" pin (NIC) doesn't have a net until it has been used
+    if( aDifferentNetsOnly && ( IsFreePad() || aOther->IsFreePad() ) )
+        return false;
+
     // check if we are not on completely different layers first
     if( !m_layers.Overlaps( aOther->m_layers ) )
         return false;

pcbnew/router/pns_item.h

@@ -81,6 +81,7 @@ public:
         m_rank = -1;
         m_routable = true;
         m_isVirtual = false;
+        m_isFreePad = false;
         m_isCompoundShapePrimitive = false;
     }
 
@@ -96,6 +97,7 @@ public:
         m_rank = aOther.m_rank;
         m_routable = aOther.m_routable;
         m_isVirtual = aOther.m_isVirtual;
+        m_isFreePad = aOther.m_isFreePad;
         m_isCompoundShapePrimitive = aOther.m_isCompoundShapePrimitive;
     }
 
@@ -232,6 +234,9 @@ public:
     void SetRoutable( bool aRoutable ) { m_routable = aRoutable; }
     bool IsRoutable() const { return m_routable; }
 
+    void SetIsFreePad( bool aIsFreePad = true ) { m_isFreePad = aIsFreePad; }
+    bool IsFreePad() const { return m_isFreePad; }
+
     bool IsVirtual() const
     {
         return m_isVirtual;
@@ -256,6 +261,7 @@ protected:
     int           m_rank;
     bool          m_routable;
     bool          m_isVirtual;
+    bool          m_isFreePad;
     bool          m_isCompoundShapePrimitive;
 };
 

pcbnew/router/pns_kicad_iface.cpp

@@ -970,6 +970,9 @@ std::unique_ptr<PNS::SOLID> PNS_KICAD_IFACE_BASE::syncPad( PAD* aPad )
     solid->SetPadToDie( aPad->GetPadToDieLength() );
     solid->SetOrientation( aPad->GetOrientation() );
 
+    if( aPad->IsFreePad() )
+        solid->SetIsFreePad();
+
     VECTOR2I wx_c = aPad->ShapePos();
     VECTOR2I offset = aPad->GetOffset();
 

pcbnew/router/pns_tool_base.cpp

@@ -133,13 +133,14 @@ ITEM* TOOL_BASE::pickSingleItem( const VECTOR2I& aWhere, int aNet, int aLayer, b
         //if( item->Parent() && !item->Parent()->ViewIsVisible() )
         //    continue;
 
-        if( aNet <= 0 || item->Net() == aNet )
+        if( item->OfKind( ITEM::SOLID_T ) && aIgnorePads )
+        {
+            continue;
+        }
+        else if( aNet <= 0 || item->Net() == aNet )
         {
             if( item->OfKind( ITEM::VIA_T | ITEM::SOLID_T ) )
             {
-                if( item->OfKind( ITEM::SOLID_T ) && aIgnorePads )
-                    continue;
-
                 SEG::ecoord d = ( item->Shape()->Centre() - aWhere ).SquaredEuclideanNorm();
 
                 if( d < dist[2] )
@@ -173,12 +174,18 @@ ITEM* TOOL_BASE::pickSingleItem( const VECTOR2I& aWhere, int aNet, int aLayer, b
                 }
             }
         }
+        else if( item->OfKind( ITEM::SOLID_T ) && item->IsFreePad() )
+        {
+            // Allow free pads only when already inside pad
+            if( item->Shape()->Collide( aWhere ) )
+            {
+                prioritized[0] = item;
+                dist[0] = 0;
+            }
+        }
         else if ( item->Net() == 0 && m_router->Settings().Mode() == RM_MarkObstacles )
         {
             // Allow unconnected items as last resort in RM_MarkObstacles mode
-            if( item->OfKind( ITEM::SOLID_T ) && aIgnorePads )
-                continue;
-
             if( item->Layers().Overlaps( tl ) )
                 prioritized[4] = item;
         }