From fde2b429b9b6cabfe2f57125ed50717d2ca011a8 Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Thu, 25 Aug 2022 17:00:18 +0100
Subject: [PATCH] Make sure pair caches are layer-specific where they need to
 be.

(cherry picked from commit 909358e643ea15031529ea6f044827d57a8f6dc2)
---
 pcbnew/drc/drc_test_provider_copper_clearance.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/pcbnew/drc/drc_test_provider_copper_clearance.cpp b/pcbnew/drc/drc_test_provider_copper_clearance.cpp
index 1fe3ce1d8a..b89d5b6291 100644
--- a/pcbnew/drc/drc_test_provider_copper_clearance.cpp
+++ b/pcbnew/drc/drc_test_provider_copper_clearance.cpp
@@ -532,7 +532,7 @@ void DRC_TEST_PROVIDER_COPPER_CLEARANCE::testTrackClearances()
 
     reportAux( wxT( "Testing %d tracks & vias..." ), m_board->Tracks().size() );
 
-    std::map< std::pair<BOARD_ITEM*, BOARD_ITEM*>, int> checkedPairs;
+    std::map< std::pair<BOARD_ITEM*, BOARD_ITEM*>, LSET> checkedPairs;
 
     for( PCB_TRACK* track : m_board->Tracks() )
     {
@@ -565,13 +565,15 @@ void DRC_TEST_PROVIDER_COPPER_CLEARANCE::testTrackClearances()
                         if( static_cast<void*>( a ) > static_cast<void*>( b ) )
                             std::swap( a, b );
 
-                        if( checkedPairs.count( { a, b } ) )
+                        auto it = checkedPairs.find( { a, b } );
+
+                        if( it != checkedPairs.end() && it->second.test( layer ) )
                         {
                             return false;
                         }
                         else
                         {
-                            checkedPairs[ { a, b } ] = 1;
+                            checkedPairs[ { a, b } ].set( layer );
                             return true;
                         }
                     },