From 2dec37f80681f346f10bb9498967341164aa88ba Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Mon, 24 Oct 2022 00:13:05 +0100
Subject: [PATCH] We must check clearance on all layers of multi-layer items.

(One layer may have a custom rule.)

Fixes https://gitlab.com/kicad/code/kicad/issues/12733
---
 pcbnew/router/pns_kicad_iface.cpp | 40 +++++++++++++++++++------------
 pcbnew/router/pns_layerset.h      | 16 +++++++++++++
 2 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/pcbnew/router/pns_kicad_iface.cpp b/pcbnew/router/pns_kicad_iface.cpp
index c4d47468df..cbc0924b8c 100644
--- a/pcbnew/router/pns_kicad_iface.cpp
+++ b/pcbnew/router/pns_kicad_iface.cpp
@@ -387,26 +387,36 @@ int PNS_PCBNEW_RULE_RESOLVER::Clearance( const PNS::ITEM* aA, const PNS::ITEM* a
         return it->second;
 
     PNS::CONSTRAINT constraint;
-    int rv = 0;
-    int layer;
+    int             rv = 0;
+    LAYER_RANGE     layers;
 
-    if( !aA->Layers().IsMultilayer() || !aB || aB->Layers().IsMultilayer() )
-        layer = aA->Layer();
+    if( !aB )
+        layers = aA->Layers();
+    else if( isEdge( aA ) )
+        layers = aB->Layers();
+    else if( isEdge( aB ) )
+        layers = aA->Layers();
     else
-        layer = aB->Layer();
+        layers = aA->Layers().Intersection( aB->Layers() );
 
-    if( isCopper( aA ) && ( !aB || isCopper( aB ) ) )
+    for( int layer = layers.Start(); layer <= layers.End(); ++layer )
     {
-        if( QueryConstraint( PNS::CONSTRAINT_TYPE::CT_CLEARANCE, aA, aB, layer, &constraint ) )
-            rv = constraint.m_Value.Min();
-    }
-
-    if( isEdge( aA ) || ( aB && isEdge( aB ) ) )
-    {
-        if( QueryConstraint( PNS::CONSTRAINT_TYPE::CT_EDGE_CLEARANCE, aA, aB, layer, &constraint ) )
+        if( isCopper( aA ) && ( !aB || isCopper( aB ) ) )
         {
-            if( constraint.m_Value.Min() > rv )
-                rv = constraint.m_Value.Min();
+            if( QueryConstraint( PNS::CONSTRAINT_TYPE::CT_CLEARANCE, aA, aB, layer, &constraint ) )
+            {
+                if( constraint.m_Value.Min() > rv )
+                    rv = constraint.m_Value.Min();
+            }
+        }
+
+        if( isEdge( aA ) || ( aB && isEdge( aB ) ) )
+        {
+            if( QueryConstraint( PNS::CONSTRAINT_TYPE::CT_EDGE_CLEARANCE, aA, aB, layer, &constraint ) )
+            {
+                if( constraint.m_Value.Min() > rv )
+                    rv = constraint.m_Value.Min();
+            }
         }
     }
 
diff --git a/pcbnew/router/pns_layerset.h b/pcbnew/router/pns_layerset.h
index f3b9d3bb15..6f3343fadd 100644
--- a/pcbnew/router/pns_layerset.h
+++ b/pcbnew/router/pns_layerset.h
@@ -105,6 +105,22 @@ public:
             m_end = aOther.m_end;
     }
 
+    LAYER_RANGE Intersection( const LAYER_RANGE& aOther ) const
+    {
+        LAYER_RANGE overlap;
+
+        overlap.m_start = std::max( m_start, aOther.m_start );
+
+        if( m_end < 0 )
+            overlap.m_end = aOther.m_end;
+        else if( aOther.m_end < 0 )
+            overlap.m_end = m_end;
+        else
+            overlap.m_end = std::min( m_end, aOther.m_end );
+
+        return overlap;
+    }
+
     ///< Shortcut for comparisons/overlap tests
     static LAYER_RANGE All()
     {