Don't show redundant ERC markers from subsheets

Fixes https://gitlab.com/kicad/code/kicad/-/issues/7016

eeschema/connection_graph.cpp

@@ -2743,6 +2743,7 @@ int CONNECTION_GRAPH::ercCheckHierSheets()
                 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_HIERACHICAL_LABEL );
                 ercItem->SetItems( unmatched.second );
                 ercItem->SetErrorMessage( msg );
+                ercItem->SetIsSheetSpecific();
 
                 SCH_MARKER* marker = new SCH_MARKER( ercItem, unmatched.second->GetPosition() );
                 sheet.LastScreen()->Append( marker );

eeschema/erc.cpp

@@ -530,6 +530,7 @@ int ERC_TESTER::TestPinToPin()
                             ERC_ITEM::Create( erc == PIN_ERROR::WARNING ? ERCE_PIN_TO_PIN_WARNING :
                                                                           ERCE_PIN_TO_PIN_ERROR );
                     ercItem->SetItems( refPin, testPin );
+                    ercItem->SetIsSheetSpecific();
 
                     ercItem->SetErrorMessage(
                             wxString::Format( _( "Pins of type %s and %s are connected" ),
@@ -602,6 +603,7 @@ int ERC_TESTER::TestMultUnitPinConflicts()
                                 pin->GetNumber(), netName, pinToNetMap[name].first ) );
 
                         ercItem->SetItems( pin, pinToNetMap[name].second );
+                        ercItem->SetIsSheetSpecific();
 
                         SCH_MARKER* marker = new SCH_MARKER( ercItem,
                                                              pin->GetTransformedPosition() );

eeschema/erc_item.h

@@ -52,12 +52,16 @@ public:
         return allItemTypes;
     }
 
+    bool IsSheetSpecific() const { return m_sheetSpecific; }
+    void SetIsSheetSpecific( bool aSpecific = true ) { m_sheetSpecific = aSpecific; }
+
 private:
     ERC_ITEM( int aErrorCode = 0, const wxString& aTitle = "", const wxString& aSettingsKey = "" )
     {
         m_errorCode     = aErrorCode;
         m_errorTitle    = aTitle;
         m_settingsKey   = aSettingsKey;
+        m_sheetSpecific = false;
     }
 
     /// A list of all ERC_ITEM types which are valid error codes
@@ -90,6 +94,9 @@ private:
     static ERC_ITEM unresolvedVariable;
     static ERC_ITEM wireDangling;
     static ERC_ITEM libSymbolIssues;
+
+    /// True if this item is specific to a sheet instance (as opposed to applying to all instances)
+    bool m_sheetSpecific;
 };
 
 

eeschema/erc_settings.cpp

@@ -264,34 +264,60 @@ void ERC_SETTINGS::ResetPinMap()
 }
 
 
+void SHEETLIST_ERC_ITEMS_PROVIDER::visitMarkers( std::function<void( SCH_MARKER* )> aVisitor )
+{
+    SCH_SHEET_LIST sheetList = m_schematic->GetSheets();
+
+    std::set<SCH_SCREEN*> seenScreens;
+
+    for( unsigned i = 0; i < sheetList.size(); i++ )
+    {
+        bool firstTime = seenScreens.count( sheetList[i].LastScreen() ) == 0;
+
+        if( firstTime )
+            seenScreens.insert( sheetList[i].LastScreen() );
+
+        for( SCH_ITEM* aItem : sheetList[i].LastScreen()->Items().OfType( SCH_MARKER_T ) )
+        {
+            SCH_MARKER* marker = static_cast<SCH_MARKER*>( aItem );
+
+            if( marker->GetMarkerType() != MARKER_BASE::MARKER_ERC )
+                continue;
+
+            // Don't show non-specific markers more than once
+            if( !firstTime &&
+                !static_cast<ERC_ITEM*>( marker->GetRCItem().get() )->IsSheetSpecific() )
+            {
+                continue;
+            }
+
+            aVisitor( marker );
+        }
+    }
+}
+
+
 void SHEETLIST_ERC_ITEMS_PROVIDER::SetSeverities( int aSeverities )
 {
     m_severities = aSeverities;
 
     m_filteredMarkers.clear();
 
-    SCH_SHEET_LIST sheetList = m_schematic->GetSheets();
     ERC_SETTINGS& settings = m_schematic->ErcSettings();
 
-    for( unsigned i = 0; i < sheetList.size(); i++ )
+    visitMarkers(
+            [&]( SCH_MARKER* aMarker )
             {
-        for( SCH_ITEM* aItem : sheetList[i].LastScreen()->Items().OfType( SCH_MARKER_T ) )
-        {
-            SCH_MARKER* marker = static_cast<SCH_MARKER*>( aItem );
                 SEVERITY markerSeverity;
 
-            if( marker->GetMarkerType() != MARKER_BASE::MARKER_ERC )
+                if( aMarker->IsExcluded() )
-                continue;
-
-            if( marker->IsExcluded() )
                     markerSeverity = RPT_SEVERITY_EXCLUSION;
                 else
-                markerSeverity = settings.GetSeverity( marker->GetRCItem()->GetErrorCode() );
+                    markerSeverity = settings.GetSeverity( aMarker->GetRCItem()->GetErrorCode() );
 
                 if( markerSeverity & m_severities )
-                m_filteredMarkers.push_back( marker );
+                    m_filteredMarkers.push_back( aMarker );
-        }
+            } );
-    }
 }
 
 
@@ -302,28 +328,21 @@ int SHEETLIST_ERC_ITEMS_PROVIDER::GetCount( int aSeverity )
 
     int count = 0;
 
-    SCH_SHEET_LIST sheetList = m_schematic->GetSheets();
     ERC_SETTINGS& settings = m_schematic->ErcSettings();
 
-    for( unsigned i = 0; i < sheetList.size(); i++ )
+    visitMarkers(
+            [&]( SCH_MARKER* aMarker )
             {
-        for( SCH_ITEM* aItem : sheetList[i].LastScreen()->Items().OfType( SCH_MARKER_T ) )
-        {
-            SCH_MARKER* marker = static_cast<SCH_MARKER*>( aItem );
                 SEVERITY markerSeverity;
 
-            if( marker->GetMarkerType() != MARKER_BASE::MARKER_ERC )
+                if( aMarker->IsExcluded() )
-                continue;
-
-            if( marker->IsExcluded() )
                     markerSeverity = RPT_SEVERITY_EXCLUSION;
                 else
-                markerSeverity = settings.GetSeverity( marker->GetRCItem()->GetErrorCode() );
+                    markerSeverity = settings.GetSeverity( aMarker->GetRCItem()->GetErrorCode() );
 
                 if( markerSeverity == aSeverity )
                     count++;
-        }
+            } );
-    }
 
     return count;
 }

eeschema/erc_settings.h

@@ -194,6 +194,10 @@ public:
     void DeleteItem( int aIndex, bool aDeep ) override;
 
     void DeleteAllItems( bool aIncludeExclusions, bool aDeep ) override;
+
+private:
+
+    void visitMarkers( std::function<void( SCH_MARKER* )> aVisitor );
 };