connection_graph.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2018 CERN
 * Copyright (C) 2021-2022 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * @author Jon Evans <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <list>
#include <future>
#include <vector>
#include <unordered_map>
#include <core/profile.h>
#include <core/kicad_algo.h>
#include <common.h>
#include <core/kicad_algo.h>
#include <erc.h>
#include <pin_type.h>
#include <sch_bus_entry.h>
#include <sch_symbol.h>
#include <sch_edit_frame.h>
#include <sch_line.h>
#include <sch_marker.h>
#include <sch_pin.h>
#include <sch_sheet.h>
#include <sch_sheet_path.h>
#include <sch_sheet_pin.h>
#include <sch_text.h>
#include <schematic.h>
#include <connection_graph.h>
#include <project/project_file.h>
#include <project/net_settings.h>
#include <widgets/ui_common.h>
#include <string_utils.h>
#include <core/thread_pool.h>
#include <wx/log.h>
 
#include <advanced_config.h> // for realtime connectivity switch in release builds
 
 
/*
 * Flag to enable connectivity profiling
 * @ingroup trace_env_vars
 */
static const wxChar DanglingProfileMask[] = wxT( "CONN_PROFILE" );
 
/*
 * Flag to enable connectivity tracing
 * @ingroup trace_env_vars
 */
static const wxChar ConnTrace[] = wxT( "CONN" );
 
 
void CONNECTION_SUBGRAPH::RemoveItem( SCH_ITEM* aItem )
{
 m_items.erase( aItem );
 m_drivers.erase( aItem );
 
 if( aItem == m_driver )
 {
 m_driver = nullptr;
 m_driver_connection = nullptr;
 }
 
 if( aItem->Type() == SCH_SHEET_PIN_T )
 m_hier_pins.erase( static_cast<SCH_SHEET_PIN*>( aItem ) );
 
 if( aItem->Type() == SCH_HIER_LABEL_T )
 m_hier_ports.erase( static_cast<SCH_HIERLABEL*>( aItem ) );
}
 
 
bool CONNECTION_SUBGRAPH::ResolveDrivers( bool aCheckMultipleDrivers )
{
 auto candidate_cmp = [&]( SCH_ITEM* a, SCH_ITEM* b ) -> bool
 {
 // meet irreflexive requirements of std::sort
 if( a == b )
 return false;
 
 SCH_CONNECTION* ac = a->Connection( &m_sheet );
 SCH_CONNECTION* bc = b->Connection( &m_sheet );
 
 // Ensure we don't pick the subset over the superset
 if( ac->IsBus() && bc->IsBus() )
 return bc->IsSubsetOf( ac );
 
 // Ensure we don't pick a hidden power pin on a regular symbol over
 // one on a power symbol
 if( a->Type() == SCH_PIN_T && b->Type() == SCH_PIN_T )
 {
 SCH_PIN* pa = static_cast<SCH_PIN*>( a );
 SCH_PIN* pb = static_cast<SCH_PIN*>( b );
 
 bool aPower = pa->GetLibPin()->GetParent()->IsPower();
 bool bPower = pb->GetLibPin()->GetParent()->IsPower();
 
 if( aPower && !bPower )
 return true;
 else if( bPower && !aPower )
 return false;
 }
 
 const wxString& a_name = GetNameForDriver( a );
 const wxString& b_name = GetNameForDriver( b );
 bool a_lowQualityName = a_name.Contains( "-Pad" );
 bool b_lowQualityName = b_name.Contains( "-Pad" );
 
 if( a_lowQualityName && !b_lowQualityName )
 return false;
 else if( b_lowQualityName && !a_lowQualityName )
 return true;
 else
 return a_name < b_name;
 };
 
 auto strong_cmp = [this]( SCH_ITEM* a, SCH_ITEM* b ) -> bool
 {
 const wxString& a_name = GetNameForDriver( a );
 const wxString& b_name = GetNameForDriver( b );
 return a_name < b_name;
 };
 
 PRIORITY highest_priority = PRIORITY::INVALID;
 std::set<SCH_ITEM*, decltype( candidate_cmp )> candidates( candidate_cmp );
 std::set<SCH_ITEM*, decltype( strong_cmp )> strong_drivers( strong_cmp );
 
 m_driver = nullptr;
 
 // Hierarchical labels are lower priority than local labels here,
 // because on the first pass we want local labels to drive subgraphs
 // so that we can identify same-sheet neighbors and link them together.
 // Hierarchical labels will end up overriding the final net name if
 // a higher-level sheet has a different name during the hierarchical
 // pass.
 
 for( SCH_ITEM* item : m_drivers )
 {
 PRIORITY item_priority = GetDriverPriority( item );
 
 if( item_priority == PRIORITY::PIN
 && !static_cast<SCH_PIN*>( item )->GetParentSymbol()->IsInNetlist() )
 continue;
 
 if( item_priority >= PRIORITY::HIER_LABEL )
 strong_drivers.insert( item );
 
 if( item_priority > highest_priority )
 {
 candidates.clear();
 candidates.insert( item );
 highest_priority = item_priority;
 }
 else if( !candidates.empty() && ( item_priority == highest_priority ) )
 {
 candidates.insert( item );
 }
 }
 
 if( highest_priority >= PRIORITY::HIER_LABEL )
 m_strong_driver = true;
 
 // Power pins are 5, global labels are 6
 m_local_driver = ( highest_priority < PRIORITY::POWER_PIN );
 
 if( !candidates.empty() )
 {
 if( candidates.size() > 1 )
 {
 if( highest_priority == PRIORITY::SHEET_PIN )
 {
 // We have multiple options, and they are all hierarchical
 // sheet pins. Let's prefer outputs over inputs.
 
 for( SCH_ITEM* c : candidates )
 {
 SCH_SHEET_PIN* p = static_cast<SCH_SHEET_PIN*>( c );
 
 if( p->GetShape() == LABEL_FLAG_SHAPE::L_OUTPUT )
 {
 m_driver = c;
 break;
 }
 }
 }
 }
 
 if( !m_driver )
 m_driver = *candidates.begin();
 }
 
 if( strong_drivers.size() > 1 )
 m_multiple_drivers = true;
 
 // Drop weak drivers
 if( m_strong_driver )
 {
 m_drivers.clear();
 m_drivers.insert( strong_drivers.begin(), strong_drivers.end() );
 }
 
 // Cache driver connection
 if( m_driver )
 {
 m_driver_connection = m_driver->Connection( &m_sheet );
 m_driver_connection->ConfigureFromLabel( GetNameForDriver( m_driver ) );
 m_driver_connection->SetDriver( m_driver );
 m_driver_connection->ClearDirty();
 }
 else if( !m_is_bus_member )
 {
 m_driver_connection = nullptr;
 }
 
 return ( m_driver != nullptr );
}
 
 
void CONNECTION_SUBGRAPH::getAllConnectedItems( std::set<std::pair<SCH_SHEET_PATH, SCH_ITEM*>>& aItems, std::set<CONNECTION_SUBGRAPH*>& aSubgraphs )
{
 CONNECTION_SUBGRAPH* sg = this;
 
 while( sg->m_absorbed_by )
 {
 wxASSERT( sg->m_graph == sg->m_absorbed_by->m_graph );
 sg = sg->m_absorbed_by;
 }
 
 aSubgraphs.insert( sg );
 aSubgraphs.insert( sg->m_absorbed_subgraphs.begin(), sg->m_absorbed_subgraphs.end() );
 
 for( SCH_ITEM* item : sg->m_items )
 aItems.emplace( m_sheet, item );
 
 for( CONNECTION_SUBGRAPH* child_sg : sg->m_hier_children )
 child_sg->getAllConnectedItems( aItems, aSubgraphs );
}
 
 
wxString CONNECTION_SUBGRAPH::GetNetName() const
{
 if( !m_driver || m_dirty )
 return "";
 
 if( !m_driver->Connection( &m_sheet ) )
 {
#ifdef CONNECTIVITY_DEBUG
 wxASSERT_MSG( false, wxS( "Tried to get the net name of an item with no connection" ) );
#endif
 
 return "";
 }
 
 return m_driver->Connection( &m_sheet )->Name();
}
 
 
std::vector<SCH_ITEM*> CONNECTION_SUBGRAPH::GetAllBusLabels() const
{
 std::vector<SCH_ITEM*> labels;
 
 for( SCH_ITEM* item : m_drivers )
 {
 switch( item->Type() )
 {
 case SCH_LABEL_T:
 case SCH_GLOBAL_LABEL_T:
 {
 CONNECTION_TYPE type = item->Connection( &m_sheet )->Type();
 
 // Only consider bus vectors
 if( type == CONNECTION_TYPE::BUS || type == CONNECTION_TYPE::BUS_GROUP )
 labels.push_back( item );
 
 break;
 }
 
 default:
 break;
 }
 }
 
 return labels;
}
 
 
std::vector<SCH_ITEM*> CONNECTION_SUBGRAPH::GetVectorBusLabels() const
{
 std::vector<SCH_ITEM*> labels;
 
 for( SCH_ITEM* item : m_drivers )
 {
 switch( item->Type() )
 {
 case SCH_LABEL_T:
 case SCH_GLOBAL_LABEL_T:
 {
 SCH_CONNECTION* label_conn = item->Connection( &m_sheet );
 
 // Only consider bus vectors
 if( label_conn->Type() == CONNECTION_TYPE::BUS )
 labels.push_back( item );
 
 break;
 }
 
 default:
 break;
 }
 }
 
 return labels;
}
 
 
wxString CONNECTION_SUBGRAPH::driverName( SCH_ITEM* aItem ) const
{
 switch( aItem->Type() )
 {
 case SCH_PIN_T:
 {
 bool forceNoConnect = m_no_connect != nullptr;
 SCH_PIN* pin = static_cast<SCH_PIN*>( aItem );
 return pin->GetDefaultNetName( m_sheet, forceNoConnect );
 break;
 }
 
 case SCH_LABEL_T:
 case SCH_GLOBAL_LABEL_T:
 case SCH_HIER_LABEL_T:
 // NB: any changes here will need corresponding changes in SCH_LABEL_BASE::cacheShownText()
 return EscapeString( static_cast<SCH_TEXT*>( aItem )->GetShownText( &m_sheet, false ),
 CTX_NETNAME );
 
 case SCH_SHEET_PIN_T:
 // Sheet pins need to use their parent sheet as their starting sheet or they will
 // resolve variables on the current sheet first
 return EscapeString( static_cast<SCH_TEXT*>( aItem )->GetShownText( nullptr, false ),
 CTX_NETNAME );
 
 default:
 wxFAIL_MSG( wxS( "Unhandled item type in GetNameForDriver" ) );
 break;
 }
 
 return wxEmptyString;
}
 
 
const wxString& CONNECTION_SUBGRAPH::GetNameForDriver( SCH_ITEM* aItem ) const
{
 if( aItem->HasCachedDriverName() )
 return aItem->GetCachedDriverName();
 
 auto it = m_driver_name_cache.find( aItem );
 
 if( it != m_driver_name_cache.end() )
 return it->second;
 
 return m_driver_name_cache.emplace( aItem, driverName( aItem ) ).first->second;
}
 
 
const wxString CONNECTION_SUBGRAPH::GetNetclassForDriver( SCH_ITEM* aItem ) const
{
 wxString netclass;
 
 aItem->RunOnChildren(
 [&]( SCH_ITEM* aChild )
 {
 if( aChild->Type() == SCH_FIELD_T )
 {
 SCH_FIELD* field = static_cast<SCH_FIELD*>( aChild );
 
 if( field->GetCanonicalName() == wxT( "Netclass" ) )
 {
 netclass = field->GetText();
 return false;
 }
 }
 
 return true;
 } );
 
 return netclass;
}
 
 
void CONNECTION_SUBGRAPH::Absorb( CONNECTION_SUBGRAPH* aOther )
{
 wxASSERT( m_sheet == aOther->m_sheet );
 
 for( SCH_ITEM* item : aOther->m_items )
 {
 item->Connection( &m_sheet )->SetSubgraphCode( m_code );
 AddItem( item );
 }
 
 m_absorbed_subgraphs.insert( aOther );
 m_absorbed_subgraphs.insert( aOther->m_absorbed_subgraphs.begin(),
 aOther->m_absorbed_subgraphs.end() );
 
 m_bus_neighbors.insert( aOther->m_bus_neighbors.begin(), aOther->m_bus_neighbors.end() );
 m_bus_parents.insert( aOther->m_bus_parents.begin(), aOther->m_bus_parents.end() );
 
 m_multiple_drivers |= aOther->m_multiple_drivers;
 
 std::function<void( CONNECTION_SUBGRAPH* )> set_absorbed_by =
 [ & ]( CONNECTION_SUBGRAPH *child )
 {
 child->m_absorbed_by = this;
 
 for( CONNECTION_SUBGRAPH* subchild : child->m_absorbed_subgraphs )
 set_absorbed_by( subchild );
 };
 
 aOther->m_absorbed = true;
 aOther->m_dirty = false;
 aOther->m_driver = nullptr;
 aOther->m_driver_connection = nullptr;
 
 set_absorbed_by( aOther );
}
 
 
void CONNECTION_SUBGRAPH::AddItem( SCH_ITEM* aItem )
{
 m_items.insert( aItem );
 
 if( aItem->Connection( &m_sheet )->IsDriver() )
 m_drivers.insert( aItem );
 
 if( aItem->Type() == SCH_SHEET_PIN_T )
 m_hier_pins.insert( static_cast<SCH_SHEET_PIN*>( aItem ) );
 else if( aItem->Type() == SCH_HIER_LABEL_T )
 m_hier_ports.insert( static_cast<SCH_HIERLABEL*>( aItem ) );
}
 
 
void CONNECTION_SUBGRAPH::UpdateItemConnections()
{
 if( !m_driver_connection )
 return;
 
 for( SCH_ITEM* item : m_items )
 {
 SCH_CONNECTION* item_conn = item->GetOrInitConnection( m_sheet, m_graph );
 
 if( !item_conn )
 continue;
 
 if( ( m_driver_connection->IsBus() && item_conn->IsNet() ) ||
 ( m_driver_connection->IsNet() && item_conn->IsBus() ) )
 {
 continue;
 }
 
 if( item != m_driver )
 {
 item_conn->Clone( *m_driver_connection );
 item_conn->ClearDirty();
 }
 }
}
 
 
CONNECTION_SUBGRAPH::PRIORITY CONNECTION_SUBGRAPH::GetDriverPriority( SCH_ITEM* aDriver )
{
 if( !aDriver )
 return PRIORITY::NONE;
 
 switch( aDriver->Type() )
 {
 case SCH_SHEET_PIN_T: return PRIORITY::SHEET_PIN;
 case SCH_HIER_LABEL_T: return PRIORITY::HIER_LABEL;
 case SCH_LABEL_T: return PRIORITY::LOCAL_LABEL;
 case SCH_GLOBAL_LABEL_T: return PRIORITY::GLOBAL;
 case SCH_PIN_T:
 {
 SCH_PIN* sch_pin = static_cast<SCH_PIN*>( aDriver );
 SCH_SYMBOL* sym = sch_pin->GetParentSymbol();
 
 if( sch_pin->IsGlobalPower() )
 return PRIORITY::POWER_PIN;
 else if( !sym || sym->GetExcludedFromBoard() || sym->GetLibSymbolRef()->GetReferenceField().GetText().StartsWith( '#' ) )
 return PRIORITY::NONE;
 else
 return PRIORITY::PIN;
 }
 
 default: return PRIORITY::NONE;
 }
}
 
 
void CONNECTION_GRAPH::Merge( CONNECTION_GRAPH& aGraph )
{
 std::copy( aGraph.m_items.begin(), aGraph.m_items.end(),
 std::back_inserter( m_items ) );
 
 for( SCH_ITEM* item : aGraph.m_items )
 item->SetConnectionGraph( this );
 
 std::copy( aGraph.m_subgraphs.begin(), aGraph.m_subgraphs.end(),
 std::back_inserter( m_subgraphs ) );
 
 for( CONNECTION_SUBGRAPH* sg : aGraph.m_subgraphs )
 {
 if( sg->m_driver_connection )
 sg->m_driver_connection->SetGraph( this );
 
 sg->m_graph = this;
 }
 
 std::copy( aGraph.m_driver_subgraphs.begin(),
 aGraph.m_driver_subgraphs.end(),
 std::back_inserter( m_driver_subgraphs ) );
 
 std::copy( aGraph.m_global_power_pins.begin(),
 aGraph.m_global_power_pins.end(),
 std::back_inserter( m_global_power_pins ) );
 
 for( auto& [key, value] : aGraph.m_net_name_to_subgraphs_map )
 m_net_name_to_subgraphs_map.insert_or_assign( key, value );
 
 for( auto& [key, value] : aGraph.m_sheet_to_subgraphs_map )
 m_sheet_to_subgraphs_map.insert_or_assign( key, value );
 
 for( auto& [key, value] : aGraph.m_net_name_to_code_map )
 m_net_name_to_code_map.insert_or_assign( key, value );
 
 for( auto& [key, value] : aGraph.m_bus_name_to_code_map )
 m_bus_name_to_code_map.insert_or_assign( key, value );
 
 for( auto& [key, value] : aGraph.m_net_code_to_subgraphs_map )
 m_net_code_to_subgraphs_map.insert_or_assign( key, value );
 
 for( auto& [key, value] : aGraph.m_item_to_subgraph_map )
 m_item_to_subgraph_map.insert_or_assign( key, value );
 
 for( auto& [key, value] : aGraph.m_local_label_cache )
 m_local_label_cache.insert_or_assign( key, value );
 
 for( auto& [key, value] : aGraph.m_global_label_cache )
 m_global_label_cache.insert_or_assign( key, value );
 
 m_last_bus_code = std::max( m_last_bus_code, aGraph.m_last_bus_code );
 m_last_net_code = std::max( m_last_net_code, aGraph.m_last_net_code );
 m_last_subgraph_code = std::max( m_last_subgraph_code, aGraph.m_last_subgraph_code );
 
}
 
 
void CONNECTION_GRAPH::Reset()
{
 for( auto& subgraph : m_subgraphs )
 {
 if( subgraph->m_graph == this )
 delete subgraph;
 }
 
 m_items.clear();
 m_subgraphs.clear();
 m_driver_subgraphs.clear();
 m_sheet_to_subgraphs_map.clear();
 m_global_power_pins.clear();
 m_bus_alias_cache.clear();
 m_net_name_to_code_map.clear();
 m_bus_name_to_code_map.clear();
 m_net_code_to_subgraphs_map.clear();
 m_net_name_to_subgraphs_map.clear();
 m_item_to_subgraph_map.clear();
 m_local_label_cache.clear();
 m_global_label_cache.clear();
 m_last_net_code = 1;
 m_last_bus_code = 1;
 m_last_subgraph_code = 1;
}
 
 
void CONNECTION_GRAPH::Recalculate( const SCH_SHEET_LIST& aSheetList, bool aUnconditional,
 std::function<void( SCH_ITEM* )>* aChangedItemHandler )
{
 PROF_TIMER recalc_time( "CONNECTION_GRAPH::Recalculate" );
 
 if( aUnconditional )
 Reset();
 
 PROF_TIMER update_items( "updateItemConnectivity" );
 
 m_sheetList = aSheetList;
 std::set<SCH_ITEM*> dirty_items;
 
 for( const SCH_SHEET_PATH& sheet : aSheetList )
 {
 std::vector<SCH_ITEM*> items;
 // Store current unit value, to regenerate it after calculations
 // (useful in complex hierarchies)
 std::vector<std::pair<SCH_SYMBOL*, int>> symbolsChanged;
 
 for( SCH_ITEM* item : sheet.LastScreen()->Items() )
 {
 if( item->IsConnectable() && ( aUnconditional || item->IsConnectivityDirty() ) )
 {
 wxLogTrace( ConnTrace, wxT( "Adding item %s to connectivity graph update" ),
 item->GetTypeDesc() );
 items.push_back( item );
 dirty_items.insert( item );
 }
 // Ensure the hierarchy info stored in SCREENS is built and up to date
 // (multi-unit symbols)
 if( item->Type() == SCH_SYMBOL_T )
 {
 SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );
 int new_unit = symbol->GetUnitSelection( &sheet );
 
 // Store the initial unit value, to regenerate it after calculations,
 // if modified
 if( symbol->GetUnit() != new_unit )
 symbolsChanged.push_back( { symbol, symbol->GetUnit() } );
 
 symbol->UpdateUnit( new_unit );
 }
 }
 
 m_items.reserve( m_items.size() + items.size() );
 
 updateItemConnectivity( sheet, items );
 
 // UpdateDanglingState() also adds connected items for SCH_TEXT
 sheet.LastScreen()->TestDanglingEnds( &sheet, aChangedItemHandler );
 
 // Restore the m_unit member, to avoid changes in current active sheet path
 // after calculations
 for( auto& item : symbolsChanged )
 {
 item.first->UpdateUnit( item.second );
 }
 }
 
 for( SCH_ITEM* item : dirty_items )
 item->SetConnectivityDirty( false );
 
 if( wxLog::IsAllowedTraceMask( DanglingProfileMask ) )
 update_items.Show();
 
 PROF_TIMER build_graph( "buildConnectionGraph" );
 
 buildConnectionGraph( aChangedItemHandler );
 
 if( wxLog::IsAllowedTraceMask( DanglingProfileMask ) )
 build_graph.Show();
 
 recalc_time.Stop();
 
 if( wxLog::IsAllowedTraceMask( DanglingProfileMask ) )
 recalc_time.Show();
}
 
std::set<std::pair<SCH_SHEET_PATH, SCH_ITEM*>> CONNECTION_GRAPH::ExtractAffectedItems(
 const std::set<SCH_ITEM*> &aItems )
{
 std::set<std::pair<SCH_SHEET_PATH, SCH_ITEM*>> retvals;
 std::set<CONNECTION_SUBGRAPH*> subgraphs;
 
 auto traverse_subgraph = [&retvals, &subgraphs]( CONNECTION_SUBGRAPH* aSubgraph )
 {
 // Find the primary subgraph on this sheet
 while( aSubgraph->m_absorbed_by )
 {
 wxASSERT( aSubgraph->m_graph == aSubgraph->m_absorbed_by->m_graph );
 aSubgraph = aSubgraph->m_absorbed_by;
 }
 
 // Find the top most connected subgraph on all sheets
 while( aSubgraph->m_hier_parent )
 {
 wxASSERT( aSubgraph->m_graph == aSubgraph->m_hier_parent->m_graph );
 aSubgraph = aSubgraph->m_hier_parent;
 }
 
 // Recurse through all subsheets to collect connected items
 aSubgraph->getAllConnectedItems( retvals, subgraphs );
 };
 
 for( SCH_ITEM* item : aItems )
 {
 auto it = m_item_to_subgraph_map.find( item );
 
 if( it == m_item_to_subgraph_map.end() )
 continue;
 
 CONNECTION_SUBGRAPH* sg = it->second;
 
 traverse_subgraph( sg );
 
 for( auto& bus_it : sg->m_bus_neighbors )
 {
 for( CONNECTION_SUBGRAPH* bus_sg : bus_it.second )
 traverse_subgraph( bus_sg );
 }
 
 for( auto& bus_it : sg->m_bus_parents )
 {
 for( CONNECTION_SUBGRAPH* bus_sg : bus_it.second )
 traverse_subgraph( bus_sg );
 }
 
 alg::delete_matching( m_items, item );
 }
 
 removeSubgraphs( subgraphs );
 
 return retvals;
}
 
 
void CONNECTION_GRAPH::removeSubgraphs( std::set<CONNECTION_SUBGRAPH*>& aSubgraphs )
{
 std::sort( m_driver_subgraphs.begin(), m_driver_subgraphs.end() );
 std::sort( m_subgraphs.begin(), m_subgraphs.end() );
 std::set<int> codes_to_remove;
 
 for( auto& el : m_sheet_to_subgraphs_map )
 {
 std::sort( el.second.begin(), el.second.end() );
 }
 
 for( CONNECTION_SUBGRAPH* sg : aSubgraphs )
 {
 for( auto& it : sg->m_bus_neighbors )
 {
 for( CONNECTION_SUBGRAPH* neighbor : it.second )
 {
 auto& parents = neighbor->m_bus_parents[it.first];
 
 for( auto test = parents.begin(); test != parents.end(); )
 {
 if( *test == sg )
 test = parents.erase( test );
 else
 ++test;
 }
 
 if( parents.empty() )
 neighbor->m_bus_parents.erase( it.first );
 }
 }
 
 for( auto& it : sg->m_bus_parents )
 {
 for( CONNECTION_SUBGRAPH* parent : it.second )
 {
 auto& neighbors = parent->m_bus_neighbors[it.first];
 
 for( auto test = neighbors.begin(); test != neighbors.end(); )
 {
 if( *test == sg )
 test = neighbors.erase( test );
 else
 ++test;
 }
 
 if( neighbors.empty() )
 parent->m_bus_neighbors.erase( it.first );
 }
 }
 
 {
 auto it = std::lower_bound( m_driver_subgraphs.begin(), m_driver_subgraphs.end(), sg );
 
 while( it != m_driver_subgraphs.end() && *it == sg )
 it = m_driver_subgraphs.erase( it );
 }
 
 {
 auto it = std::lower_bound( m_subgraphs.begin(), m_subgraphs.end(), sg );
 
 while( it != m_subgraphs.end() && *it == sg )
 it = m_subgraphs.erase( it );
 }
 
 for( auto& el : m_sheet_to_subgraphs_map )
 {
 auto it = std::lower_bound( el.second.begin(), el.second.end(), sg );
 
 while( it != el.second.end() && *it == sg )
 it = el.second.erase( it );
 }
 
 auto remove_sg = [sg]( auto it ) -> bool
 {
 for( const CONNECTION_SUBGRAPH* test_sg : it->second )
 {
 if( sg == test_sg )
 return true;
 }
 
 return false;
 };
 
 for( auto it = m_global_label_cache.begin(); it != m_global_label_cache.end(); )
 {
 if( remove_sg( it ) )
 it = m_global_label_cache.erase( it );
 else
 ++it;
 }
 
 for( auto it = m_local_label_cache.begin(); it != m_local_label_cache.end(); )
 {
 if( remove_sg( it ) )
 it = m_local_label_cache.erase( it );
 else
 ++it;
 }
 
 for( auto it = m_net_code_to_subgraphs_map.begin(); it != m_net_code_to_subgraphs_map.end(); )
 {
 if( remove_sg( it ) )
 {
 codes_to_remove.insert( it->first.Netcode );
 it = m_net_code_to_subgraphs_map.erase( it );
 }
 else
 ++it;
 }
 
 for( auto it = m_net_name_to_subgraphs_map.begin(); it != m_net_name_to_subgraphs_map.end(); )
 {
 if( remove_sg( it ) )
 it = m_net_name_to_subgraphs_map.erase( it );
 else
 ++it;
 }
 
 for( auto it = m_item_to_subgraph_map.begin(); it != m_item_to_subgraph_map.end(); )
 {
 if( it->second == sg )
 it = m_item_to_subgraph_map.erase( it );
 else
 ++it;
 }
 
 
 }
 
 for( auto it = m_net_name_to_code_map.begin(); it != m_net_name_to_code_map.end(); )
 {
 if( codes_to_remove.find( it->second ) != codes_to_remove.end() )
 it = m_net_name_to_code_map.erase( it );
 else
 ++it;
 }
 
 for( auto it = m_bus_name_to_code_map.begin(); it != m_bus_name_to_code_map.end(); )
 {
 if( codes_to_remove.find( it->second ) != codes_to_remove.end() )
 it = m_bus_name_to_code_map.erase( it );
 else
 ++it;
 }
 
 for( CONNECTION_SUBGRAPH* sg : aSubgraphs )
 {
 sg->m_code = -1;
 sg->m_graph = nullptr;
 delete sg;
 }
}
 
 
void CONNECTION_GRAPH::updateItemConnectivity( const SCH_SHEET_PATH& aSheet,
 const std::vector<SCH_ITEM*>& aItemList )
{
 std::map<VECTOR2I, std::vector<SCH_ITEM*>> connection_map;
 
 for( SCH_ITEM* item : aItemList )
 {
 std::vector<VECTOR2I> points = item->GetConnectionPoints();
 item->ConnectedItems( aSheet ).clear();
 
 if( item->Type() == SCH_SHEET_T )
 {
 for( SCH_SHEET_PIN* pin : static_cast<SCH_SHEET*>( item )->GetPins() )
 {
 pin->InitializeConnection( aSheet, this );
 
 pin->ConnectedItems( aSheet ).clear();
 
 connection_map[ pin->GetTextPos() ].push_back( pin );
 m_items.emplace_back( pin );
 }
 }
 else if( item->Type() == SCH_SYMBOL_T )
 {
 SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );
 
 for( SCH_PIN* pin : symbol->GetPins( &aSheet ) )
 {
 SCH_CONNECTION* conn = pin->InitializeConnection( aSheet, this );
 
 VECTOR2I pos = pin->GetPosition();
 
 // because calling the first time is not thread-safe
 wxString name = pin->GetDefaultNetName( aSheet );
 pin->ConnectedItems( aSheet ).clear();
 
 // power symbol pins need to be post-processed later
 if( pin->IsGlobalPower() )
 {
 conn->SetName( name );
 m_global_power_pins.emplace_back( std::make_pair( aSheet, pin ) );
 }
 
 connection_map[ pos ].push_back( pin );
 m_items.emplace_back( pin );
 }
 }
 else
 {
 m_items.emplace_back( item );
 SCH_CONNECTION* conn = item->InitializeConnection( aSheet, this );
 
 // Set bus/net property here so that the propagation code uses it
 switch( item->Type() )
 {
 case SCH_LINE_T:
 conn->SetType( item->GetLayer() == LAYER_BUS ? CONNECTION_TYPE::BUS :
 CONNECTION_TYPE::NET );
 break;
 
 case SCH_BUS_BUS_ENTRY_T:
 conn->SetType( CONNECTION_TYPE::BUS );
 // clean previous (old) links:
 static_cast<SCH_BUS_BUS_ENTRY*>( item )->m_connected_bus_items[0] = nullptr;
 static_cast<SCH_BUS_BUS_ENTRY*>( item )->m_connected_bus_items[1] = nullptr;
 break;
 
 case SCH_PIN_T:
 conn->SetType( CONNECTION_TYPE::NET );
 break;
 
 case SCH_BUS_WIRE_ENTRY_T:
 conn->SetType( CONNECTION_TYPE::NET );
 // clean previous (old) link:
 static_cast<SCH_BUS_WIRE_ENTRY*>( item )->m_connected_bus_item = nullptr;
 break;
 
 default:
 break;
 }
 
 for( const VECTOR2I& point : points )
 connection_map[ point ].push_back( item );
 }
 }
 
 for( const auto& it : connection_map )
 {
 std::vector<SCH_ITEM*> connection_vec = it.second;
 std::sort( connection_vec.begin(), connection_vec.end() );
 alg::remove_duplicates( connection_vec );
 
 // Pre-scan to see if we have a bus at this location
 SCH_LINE* busLine = aSheet.LastScreen()->GetBus( it.first );
 
 std::mutex update_mutex;
 
 auto update_lambda = [&]( SCH_ITEM* connected_item ) -> size_t
 {
 // Bus entries are special: they can have connection points in the
 // middle of a wire segment, because the junction algo doesn't split
 // the segment in two where you place a bus entry. This means that
 // bus entries that don't land on the end of a line segment need to
 // have "virtual" connection points to the segments they graphically
 // touch.
 if( connected_item->Type() == SCH_BUS_WIRE_ENTRY_T )
 {
 // If this location only has the connection point of the bus
 // entry itself, this means that either the bus entry is not
 // connected to anything graphically, or that it is connected to
 // a segment at some point other than at one of the endpoints.
 if( connection_vec.size() == 1 )
 {
 if( busLine )
 {
 auto bus_entry = static_cast<SCH_BUS_WIRE_ENTRY*>( connected_item );
 bus_entry->m_connected_bus_item = busLine;
 }
 }
 }
 
 // Bus-to-bus entries are treated just like bus wires
 else if( connected_item->Type() == SCH_BUS_BUS_ENTRY_T )
 {
 if( connection_vec.size() < 2 )
 {
 if( busLine )
 {
 auto bus_entry = static_cast<SCH_BUS_BUS_ENTRY*>( connected_item );
 
 if( it.first == bus_entry->GetPosition() )
 bus_entry->m_connected_bus_items[0] = busLine;
 else
 bus_entry->m_connected_bus_items[1] = busLine;
 
 std::lock_guard<std::mutex> lock( update_mutex );
 bus_entry->AddConnectionTo( aSheet, busLine );
 busLine->AddConnectionTo( aSheet, bus_entry );
 }
 }
 }
 
 // Change junctions to be on bus junction layer if they are touching a bus
 else if( connected_item->Type() == SCH_JUNCTION_T )
 {
 connected_item->SetLayer( busLine ? LAYER_BUS_JUNCTION : LAYER_JUNCTION );
 }
 
 SCH_ITEM_SET& connected_set = connected_item->ConnectedItems( aSheet );
 connected_set.reserve( connection_vec.size() );
 
 for( SCH_ITEM* test_item : connection_vec )
 {
 bool bus_connection_ok = true;
 
 if( test_item == connected_item )
 continue;
 
 // Set up the link between the bus entry net and the bus
 if( connected_item->Type() == SCH_BUS_WIRE_ENTRY_T )
 {
 if( test_item->GetLayer() == LAYER_BUS )
 {
 auto bus_entry = static_cast<SCH_BUS_WIRE_ENTRY*>( connected_item );
 bus_entry->m_connected_bus_item = test_item;
 }
 }
 
 // Bus entries only connect to bus lines on the end that is touching a bus line.
 // If the user has overlapped another net line with the endpoint of the bus entry
 // where the entry connects to a bus, we don't want to short-circuit it.
 if( connected_item->Type() == SCH_BUS_WIRE_ENTRY_T )
 {
 bus_connection_ok = !busLine || test_item->GetLayer() == LAYER_BUS;
 }
 else if( test_item->Type() == SCH_BUS_WIRE_ENTRY_T )
 {
 bus_connection_ok = !busLine || connected_item->GetLayer() == LAYER_BUS;
 }
 
 if( connected_item->ConnectionPropagatesTo( test_item ) &&
 test_item->ConnectionPropagatesTo( connected_item ) &&
 bus_connection_ok )
 {
 connected_set.push_back( test_item );
 }
 }
 
 // If we got this far and did not find a connected bus item for a bus entry,
 // we should do a manual scan in case there is a bus item on this connection
 // point but we didn't pick it up earlier because there is *also* a net item here.
 if( connected_item->Type() == SCH_BUS_WIRE_ENTRY_T )
 {
 auto bus_entry = static_cast<SCH_BUS_WIRE_ENTRY*>( connected_item );
 
 if( !bus_entry->m_connected_bus_item )
 {
 SCH_SCREEN* screen = aSheet.LastScreen();
 SCH_LINE* bus = screen->GetBus( it.first );
 
 if( bus )
 bus_entry->m_connected_bus_item = bus;
 }
 }
 
 return 1;
 };
 
 thread_pool& tp = GetKiCadThreadPool();
 
 tp.push_loop( connection_vec.size(),
 [&]( const int a, const int b)
 {
 for( int ii = a; ii < b; ++ii )
 update_lambda( connection_vec[ii] );
 });
 tp.wait_for_tasks();
 }
}
 
 
void CONNECTION_GRAPH::buildItemSubGraphs()
{
 // Recache all bus aliases for later use
 wxCHECK_RET( m_schematic, wxS( "Connection graph cannot be built without schematic pointer" ) );
 
 SCH_SHEET_LIST all_sheets = m_schematic->GetSheets();
 
 for( unsigned i = 0; i < all_sheets.size(); i++ )
 {
 for( const std::shared_ptr<BUS_ALIAS>& alias : all_sheets[i].LastScreen()->GetBusAliases() )
 m_bus_alias_cache[ alias->GetName() ] = alias;
 }
 
 // Build subgraphs from items (on a per-sheet basis)
 
 for( SCH_ITEM* item : m_items )
 {
 for( const auto& it : item->m_connection_map )
 {
 const SCH_SHEET_PATH& sheet = it.first;
 SCH_CONNECTION* connection = it.second;
 
 if( connection->SubgraphCode() == 0 )
 {
 CONNECTION_SUBGRAPH* subgraph = new CONNECTION_SUBGRAPH( this );
 
 subgraph->m_code = m_last_subgraph_code++;
 subgraph->m_sheet = sheet;
 
 subgraph->AddItem( item );
 
 connection->SetSubgraphCode( subgraph->m_code );
 m_item_to_subgraph_map[item] = subgraph;
 
 std::list<SCH_ITEM*> memberlist;
 
 auto get_items =
 [&]( SCH_ITEM* aItem ) -> bool
 {
 SCH_CONNECTION* conn = aItem->GetOrInitConnection( sheet, this );
 bool unique = !( aItem->GetFlags() & CANDIDATE );
 
 if( conn && !conn->SubgraphCode() )
 aItem->SetFlags( CANDIDATE );
 
 return ( unique && conn && ( conn->SubgraphCode() == 0 ) );
 };
 
 std::copy_if( item->ConnectedItems( sheet ).begin(),
 item->ConnectedItems( sheet ).end(),
 std::back_inserter( memberlist ), get_items );
 
 for( SCH_ITEM* connected_item : memberlist )
 {
 if( connected_item->Type() == SCH_NO_CONNECT_T )
 subgraph->m_no_connect = connected_item;
 
 SCH_CONNECTION* connected_conn = connected_item->Connection( &sheet );
 
 wxASSERT( connected_conn );
 
 if( connected_conn->SubgraphCode() == 0 )
 {
 connected_conn->SetSubgraphCode( subgraph->m_code );
 m_item_to_subgraph_map[connected_item] = subgraph;
 subgraph->AddItem( connected_item );
 SCH_ITEM_SET& citemset = connected_item->ConnectedItems( sheet );
 
 for( SCH_ITEM* citem : citemset )
 {
 if( citem->HasFlag( CANDIDATE ) )
 continue;
 
 if( get_items( citem ) )
 memberlist.push_back( citem );
 }
 }
 }
 
 for( SCH_ITEM* connected_item : memberlist )
 connected_item->ClearFlags( CANDIDATE );
 
 subgraph->m_dirty = true;
 m_subgraphs.push_back( subgraph );
 }
 }
 }
 
}
 
void CONNECTION_GRAPH::resolveAllDrivers()
{
 // Resolve drivers for subgraphs and propagate connectivity info
 std::vector<CONNECTION_SUBGRAPH*> dirty_graphs;
 
 std::copy_if( m_subgraphs.begin(), m_subgraphs.end(), std::back_inserter( dirty_graphs ),
 [&] ( const CONNECTION_SUBGRAPH* candidate )
 {
 return candidate->m_dirty;
 } );
 
 std::vector<std::future<size_t>> returns( dirty_graphs.size() );
 
 auto update_lambda = []( CONNECTION_SUBGRAPH* subgraph ) -> size_t
 {
 if( !subgraph->m_dirty )
 return 0;
 
 // Special processing for some items
 for( SCH_ITEM* item : subgraph->m_items )
 {
 switch( item->Type() )
 {
 case SCH_NO_CONNECT_T:
 subgraph->m_no_connect = item;
 break;
 
 case SCH_BUS_WIRE_ENTRY_T:
 subgraph->m_bus_entry = item;
 break;
 
 case SCH_PIN_T:
 {
 auto pin = static_cast<SCH_PIN*>( item );
 
 if( pin->GetType() == ELECTRICAL_PINTYPE::PT_NC )
 subgraph->m_no_connect = item;
 
 break;
 }
 
 default:
 break;
 }
 }
 
 subgraph->ResolveDrivers( true );
 subgraph->m_dirty = false;
 
 return 1;
 };
 
 thread_pool& tp = GetKiCadThreadPool();
 
 tp.push_loop( dirty_graphs.size(),
 [&]( const int a, const int b)
 {
 for( int ii = a; ii < b; ++ii )
 update_lambda( dirty_graphs[ii] );
 });
 tp.wait_for_tasks();
 
 // Now discard any non-driven subgraphs from further consideration
 
 std::copy_if( m_subgraphs.begin(), m_subgraphs.end(), std::back_inserter( m_driver_subgraphs ),
 [&] ( const CONNECTION_SUBGRAPH* candidate ) -> bool
 {
 return candidate->m_driver;
 } );
}
 
 
void CONNECTION_GRAPH::collectAllDriverValues()
{
 // Check for subgraphs with the same net name but only weak drivers.
 // For example, two wires that are both connected to hierarchical
 // sheet pins that happen to have the same name, but are not the same.
 
 for( auto&& subgraph : m_driver_subgraphs )
 {
 wxString full_name = subgraph->m_driver_connection->Name();
 wxString name = subgraph->m_driver_connection->Name( true );
 m_net_name_to_subgraphs_map[full_name].emplace_back( subgraph );
 
 // For vector buses, we need to cache the prefix also, as two different instances of the
 // weakly driven pin may have the same prefix but different vector start and end. We need
 // to treat those as needing renaming also, because otherwise if they end up on a sheet with
 // common usage, they will be incorrectly merged.
 if( subgraph->m_driver_connection->Type() == CONNECTION_TYPE::BUS )
 {
 wxString prefixOnly = full_name.BeforeFirst( '[' ) + wxT( "[]" );
 m_net_name_to_subgraphs_map[prefixOnly].emplace_back( subgraph );
 }
 
 subgraph->m_dirty = true;
 
 if( subgraph->m_strong_driver )
 {
 SCH_ITEM* driver = subgraph->m_driver;
 SCH_SHEET_PATH sheet = subgraph->m_sheet;
 
 switch( driver->Type() )
 {
 case SCH_LABEL_T:
 case SCH_HIER_LABEL_T:
 {
 m_local_label_cache[std::make_pair( sheet, name )].push_back( subgraph );
 break;
 }
 case SCH_GLOBAL_LABEL_T:
 {
 m_global_label_cache[name].push_back( subgraph );
 break;
 }
 case SCH_PIN_T:
 {
 SCH_PIN* pin = static_cast<SCH_PIN*>( driver );
 wxASSERT( pin->IsGlobalPower() );
 m_global_label_cache[name].push_back( subgraph );
 break;
 }
 default:
 {
 UNITS_PROVIDER unitsProvider( schIUScale, EDA_UNITS::MILLIMETRES );
 
 wxLogTrace( ConnTrace, wxS( "Unexpected strong driver %s" ),
 driver->GetItemDescription( &unitsProvider ) );
 break;
 }
 }
 }
 }
}
 
 
void CONNECTION_GRAPH::generateBusAliasMembers()
{
 std::vector<CONNECTION_SUBGRAPH*> new_subgraphs;
 
 for( CONNECTION_SUBGRAPH* subgraph : m_driver_subgraphs )
 {
 SCH_ITEM_SET vec = subgraph->GetAllBusLabels();
 
 for( SCH_ITEM* item : vec )
 {
 SCH_LABEL_BASE* label = static_cast<SCH_LABEL_BASE*>( item );
 
 SCH_CONNECTION dummy( item, subgraph->m_sheet );
 dummy.SetGraph( this );
 dummy.ConfigureFromLabel( label->GetText() );
 
 wxLogTrace( ConnTrace, wxS( "new bus label (%s)" ), label->GetText() );
 
 for( const auto& conn : dummy.Members() )
 {
 wxString name = conn->FullLocalName();
 
 CONNECTION_SUBGRAPH* new_sg = new CONNECTION_SUBGRAPH( this );
 SCH_CONNECTION* new_conn = new SCH_CONNECTION( item, subgraph->m_sheet );
 new_conn->SetGraph( this );
 
 new_conn->SetName( name );
 new_conn->SetType( CONNECTION_TYPE::NET );
 int code = assignNewNetCode( *new_conn );
 
 wxLogTrace( ConnTrace, wxS( "SG(%ld), Adding full local name (%s) with sg (%d) on subsheet %s" ), subgraph->m_code,
 name, code, subgraph->m_sheet.PathHumanReadable() );
 
 new_sg->m_driver_connection = new_conn;
 new_sg->m_code = m_last_subgraph_code++;
 new_sg->m_sheet = subgraph->GetSheet();
 new_sg->m_is_bus_member = true;
 new_sg->m_strong_driver = true;
 
 NET_NAME_CODE_CACHE_KEY key = { new_sg->GetNetName(), code };
 m_net_code_to_subgraphs_map[ key ].push_back( new_sg );
 m_net_name_to_subgraphs_map[ name ].push_back( new_sg );
 m_subgraphs.push_back( new_sg );
 new_subgraphs.push_back( new_sg );
 }
 }
 }
 
 std::copy( new_subgraphs.begin(), new_subgraphs.end(), std::back_inserter( m_driver_subgraphs ) );
}
 
void CONNECTION_GRAPH::generateGlobalPowerPinSubGraphs()
{
 // Generate subgraphs for global power pins. These will be merged with other subgraphs
 // on the same sheet in the next loop.
 // These are NOT limited to power symbols, we support legacy invisible + power-in pins
 // on non-power symbols.
 
 std::unordered_map<int, CONNECTION_SUBGRAPH*> global_power_pin_subgraphs;
 
 for( const auto& it : m_global_power_pins )
 {
 SCH_SHEET_PATH sheet = it.first;
 SCH_PIN* pin = it.second;
 
 if( !pin->ConnectedItems( sheet ).empty() && !pin->GetLibPin()->GetParent()->IsPower() )
 {
 // ERC will warn about this: user has wired up an invisible pin
 continue;
 }
 
 SCH_CONNECTION* connection = pin->GetOrInitConnection( sheet, this );
 
 // If this pin already has a subgraph, don't need to process
 if( !connection || connection->SubgraphCode() > 0 )
 continue;
 
 // Proper modern power symbols get their net name from the value field
 // in the symbol, but we support legacy non-power symbols with global
 // power connections based on invisible, power-in, pin's names.
 if( pin->GetLibPin()->GetParent()->IsPower() )
 connection->SetName( pin->GetParentSymbol()->GetValueFieldText( true, &sheet, false ) );
 else
 connection->SetName( pin->GetShownName() );
 
 int code = assignNewNetCode( *connection );
 
 connection->SetNetCode( code );
 
 CONNECTION_SUBGRAPH* subgraph;
 auto jj = global_power_pin_subgraphs.find( code );
 
 if( jj != global_power_pin_subgraphs.end() )
 {
 subgraph = jj->second;
 subgraph->AddItem( pin );
 }
 else
 {
 subgraph = new CONNECTION_SUBGRAPH( this );
 
 subgraph->m_code = m_last_subgraph_code++;
 subgraph->m_sheet = sheet;
 
 subgraph->AddItem( pin );
 subgraph->ResolveDrivers();
 
 NET_NAME_CODE_CACHE_KEY key = { subgraph->GetNetName(), code };
 m_net_code_to_subgraphs_map[ key ].push_back( subgraph );
 m_subgraphs.push_back( subgraph );
 m_driver_subgraphs.push_back( subgraph );
 
 global_power_pin_subgraphs[code] = subgraph;
 }
 
 connection->SetSubgraphCode( subgraph->m_code );
 }
}
 
 
void CONNECTION_GRAPH::processSubGraphs()
{
 // Here we do all the local (sheet) processing of each subgraph, including assigning net
 // codes, merging subgraphs together that use label connections, etc.
 
 // Cache remaining valid subgraphs by sheet path
 for( CONNECTION_SUBGRAPH* subgraph : m_driver_subgraphs )
 m_sheet_to_subgraphs_map[ subgraph->m_sheet ].emplace_back( subgraph );
 
 std::unordered_set<CONNECTION_SUBGRAPH*> invalidated_subgraphs;
 
 for( CONNECTION_SUBGRAPH* subgraph : m_driver_subgraphs )
 {
 if( subgraph->m_absorbed )
 continue;
 
 SCH_CONNECTION* connection = subgraph->m_driver_connection;
 SCH_SHEET_PATH sheet = subgraph->m_sheet;
 wxString name = connection->Name();
 
 // Test subgraphs with weak drivers for net name conflicts and fix them
 unsigned suffix = 1;
 
 auto create_new_name =
 [&suffix]( SCH_CONNECTION* aConn ) -> wxString
 {
 wxString newName;
 wxString suffixStr = std::to_wstring( suffix );
 
 // For group buses with a prefix, we can add the suffix to the prefix.
 // If they don't have a prefix, we force the creation of a prefix so that
 // two buses don't get inadvertently shorted together.
 if( aConn->Type() == CONNECTION_TYPE::BUS_GROUP )
 {
 wxString prefix = aConn->BusPrefix();
 
 if( prefix.empty() )
 prefix = wxT( "BUS" ); // So result will be "BUS_1{...}"
 
 wxString oldName = aConn->Name().AfterFirst( '{' );
 
 newName << prefix << wxT( "_" ) << suffixStr << wxT( "{" ) << oldName;
 
 aConn->ConfigureFromLabel( newName );
 }
 else
 {
 newName << aConn->Name() << wxT( "_" ) << suffixStr;
 aConn->SetSuffix( wxString( wxT( "_" ) ) << suffixStr );
 }
 
 suffix++;
 return newName;
 };
 
 if( !subgraph->m_strong_driver )
 {
 std::vector<CONNECTION_SUBGRAPH*>* vec = &m_net_name_to_subgraphs_map.at( name );
 
 // If we are a unique bus vector, check if we aren't actually unique because of another
 // subgraph with a similar bus vector
 if( vec->size() <= 1 && subgraph->m_driver_connection->Type() == CONNECTION_TYPE::BUS )
 {
 wxString prefixOnly = name.BeforeFirst( '[' ) + wxT( "[]" );
 vec = &m_net_name_to_subgraphs_map.at( prefixOnly );
 }
 
 if( vec->size() > 1 )
 {
 wxString new_name = create_new_name( connection );
 
 while( m_net_name_to_subgraphs_map.count( new_name ) )
 new_name = create_new_name( connection );
 
 wxLogTrace( ConnTrace, wxS( "%ld (%s) is weakly driven and not unique. Changing to %s." ),
 subgraph->m_code, name, new_name );
 
 alg::delete_matching( *vec, subgraph );
 
 m_net_name_to_subgraphs_map[new_name].emplace_back( subgraph );
 
 name = new_name;
 }
 else if( subgraph->m_driver )
 {
 // If there is no conflict, promote sheet pins to be strong drivers so that they
 // will be considered below for propagation/merging.
 
 // It is possible for this to generate a conflict if the sheet pin has the same
 // name as a global label on the same sheet, because global merging will then treat
 // this subgraph as if it had a matching local label. So, for those cases, we
 // don't apply this promotion
 
 if( subgraph->m_driver->Type() == SCH_SHEET_PIN_T )
 {
 bool conflict = false;
 wxString global_name = connection->Name( true );
 auto kk = m_net_name_to_subgraphs_map.find( global_name );
 
 if( kk != m_net_name_to_subgraphs_map.end() )
 {
 // A global will conflict if it is on the same sheet as this subgraph, since
 // it would be connected by implicit local label linking
 std::vector<CONNECTION_SUBGRAPH*>& candidates = kk->second;
 
 for( const CONNECTION_SUBGRAPH* candidate : candidates )
 {
 if( candidate->m_sheet == sheet )
 conflict = true;
 }
 }
 
 if( conflict )
 {
 wxLogTrace( ConnTrace,
 wxS( "%ld (%s) skipped for promotion due to potential conflict" ),
 subgraph->m_code, name );
 }
 else
 {
 UNITS_PROVIDER unitsProvider( schIUScale, EDA_UNITS::MILLIMETRES );
 
 wxLogTrace( ConnTrace,
 wxS( "%ld (%s) weakly driven by unique sheet pin %s, promoting" ),
 subgraph->m_code, name,
 subgraph->m_driver->GetItemDescription( &unitsProvider ) );
 
 subgraph->m_strong_driver = true;
 }
 }
 }
 }
 
 // Assign net codes
 
 if( connection->IsBus() )
 {
 int code = -1;
 auto it = m_bus_name_to_code_map.find( name );
 
 if( it != m_bus_name_to_code_map.end() )
 {
 code = it->second;
 }
 else
 {
 code = m_last_bus_code++;
 m_bus_name_to_code_map[ name ] = code;
 }
 
 connection->SetBusCode( code );
 assignNetCodesToBus( connection );
 }
 else
 {
 assignNewNetCode( *connection );
 }
 
 // Reset the flag for the next loop below
 subgraph->m_dirty = true;
 
 // Next, we merge together subgraphs that have label connections, and create
 // neighbor links for subgraphs that are part of a bus on the same sheet.
 // For merging, we consider each possible strong driver.
 
 // If this subgraph doesn't have a strong driver, let's skip it, since there is no
 // way it will be merged with anything.
 
 if( !subgraph->m_strong_driver )
 continue;
 
 // candidate_subgraphs will contain each valid, non-bus subgraph on the same sheet
 // as the subgraph we are considering that has a strong driver.
 // Weakly driven subgraphs are not considered since they will never be absorbed or
 // form neighbor links.
 
 std::vector<CONNECTION_SUBGRAPH*> candidate_subgraphs;
 std::copy_if( m_sheet_to_subgraphs_map[ subgraph->m_sheet ].begin(),
 m_sheet_to_subgraphs_map[ subgraph->m_sheet ].end(),
 std::back_inserter( candidate_subgraphs ),
 [&] ( const CONNECTION_SUBGRAPH* candidate )
 {
 return ( !candidate->m_absorbed &&
 candidate->m_strong_driver &&
 candidate != subgraph );
 } );
 
 // This is a list of connections on the current subgraph to compare to the
 // drivers of each candidate subgraph. If the current subgraph is a bus,
 // we should consider each bus member.
 std::vector< std::shared_ptr<SCH_CONNECTION> > connections_to_check;
 
 // Also check the main driving connection
 connections_to_check.push_back( std::make_shared<SCH_CONNECTION>( *connection ) );
 
 auto add_connections_to_check =
 [&] ( CONNECTION_SUBGRAPH* aSubgraph )
 {
 for( SCH_ITEM* possible_driver : aSubgraph->m_items )
 {
 if( possible_driver == aSubgraph->m_driver )
 continue;
 
 auto c = getDefaultConnection( possible_driver, aSubgraph );
 
 if( c )
 {
 if( c->Type() != aSubgraph->m_driver_connection->Type() )
 continue;
 
 if( c->Name( true ) == aSubgraph->m_driver_connection->Name( true ) )
 continue;
 
 connections_to_check.push_back( c );
 wxLogTrace( ConnTrace,
 wxS( "%lu (%s): Adding secondary driver %s" ), aSubgraph->m_code,
 aSubgraph->m_driver_connection->Name( true ),
 c->Name( true ) );
 }
 }
 };
 
 // Now add other strong drivers
 // The actual connection attached to these items will have been overwritten
 // by the chosen driver of the subgraph, so we need to create a dummy connection
 add_connections_to_check( subgraph );
 
 std::set<SCH_CONNECTION*> checked_connections;
 
 for( unsigned i = 0; i < connections_to_check.size(); i++ )
 {
 auto member = connections_to_check[i];
 
 // Don't check the same connection twice
 if( !checked_connections.insert( member.get() ).second )
 continue;
 
 if( member->IsBus() )
 {
 connections_to_check.insert( connections_to_check.end(),
 member->Members().begin(),
 member->Members().end() );
 }
 
 wxString test_name = member->Name( true );
 
 for( CONNECTION_SUBGRAPH* candidate : candidate_subgraphs )
 {
 if( candidate->m_absorbed || candidate == subgraph )
 continue;
 
 bool match = false;
 
 if( candidate->m_driver_connection->Name( true ) == test_name )
 {
 match = true;
 }
 else
 {
 if( !candidate->m_multiple_drivers )
 continue;
 
 for( SCH_ITEM *driver : candidate->m_drivers )
 {
 if( driver == candidate->m_driver )
 continue;
 
 // Sheet pins are not candidates for merging
 if( driver->Type() == SCH_SHEET_PIN_T )
 continue;
 
 if( driver->Type() == SCH_PIN_T )
 {
 auto pin = static_cast<SCH_PIN*>( driver );
 
 if( pin->IsGlobalPower()
 && pin->GetDefaultNetName( sheet ) == test_name )
 {
 match = true;
 break;
 }
 }
 else
 {
 wxASSERT( driver->Type() == SCH_LABEL_T ||
 driver->Type() == SCH_GLOBAL_LABEL_T ||
 driver->Type() == SCH_HIER_LABEL_T );
 
 if( subgraph->GetNameForDriver( driver ) == test_name )
 {
 match = true;
 break;
 }
 }
 }
 }
 
 if( match )
 {
 if( connection->IsBus() && candidate->m_driver_connection->IsNet() )
 {
 wxLogTrace( ConnTrace, wxS( "%lu (%s) has bus child %lu (%s)" ), subgraph->m_code,
 connection->Name(), candidate->m_code, member->Name() );
 
 subgraph->m_bus_neighbors[member].insert( candidate );
 candidate->m_bus_parents[member].insert( subgraph );
 }
 else
 {
 wxLogTrace( ConnTrace, wxS( "%lu (%s) absorbs neighbor %lu (%s)" ),
 subgraph->m_code, connection->Name(),
 candidate->m_code, candidate->m_driver_connection->Name() );
 
 // Candidate may have other non-chosen drivers we need to follow
 add_connections_to_check( candidate );
 
 subgraph->Absorb( candidate );
 invalidated_subgraphs.insert( subgraph );
 }
 }
 }
 }
 }
 
 // Update any subgraph that was invalidated above
 for( CONNECTION_SUBGRAPH* subgraph : invalidated_subgraphs )
 {
 if( subgraph->m_absorbed )
 continue;
 
 if( !subgraph->ResolveDrivers() )
 continue;
 
 if( subgraph->m_driver_connection->IsBus() )
 assignNetCodesToBus( subgraph->m_driver_connection );
 else
 assignNewNetCode( *subgraph->m_driver_connection );
 
 wxLogTrace( ConnTrace, wxS( "Re-resolving drivers for %lu (%s)" ), subgraph->m_code,
 subgraph->m_driver_connection->Name() );
 }
 
}
 
 
// TODO(JE) This won't give the same subgraph IDs (and eventually net/graph codes)
// to the same subgraph necessarily if it runs over and over again on the same
// sheet. We need:
//
// a) a cache of net/bus codes, like used before
// b) to persist the CONNECTION_GRAPH globally so the cache is persistent,
// c) some way of trying to avoid changing net names. so we should keep track
// of the previous driver of a net, and if it comes down to choosing between
// equally-prioritized drivers, choose the one that already exists as a driver
// on some portion of the items.
 
 
void CONNECTION_GRAPH::buildConnectionGraph( std::function<void( SCH_ITEM* )>* aChangedItemHandler )
{
 // Recache all bus aliases for later use
 wxCHECK_RET( m_schematic, wxT( "Connection graph cannot be built without schematic pointer" ) );
 
 SCH_SHEET_LIST all_sheets = m_schematic->GetSheets();
 
 for( unsigned i = 0; i < all_sheets.size(); i++ )
 {
 for( const std::shared_ptr<BUS_ALIAS>& alias : all_sheets[i].LastScreen()->GetBusAliases() )
 m_bus_alias_cache[ alias->GetName() ] = alias;
 }
 
 PROF_TIMER sub_graph( "buildItemSubGraphs" );
 buildItemSubGraphs();
 
 if( wxLog::IsAllowedTraceMask( DanglingProfileMask ) )
 sub_graph.Show();
 
 
 resolveAllDrivers();
 
 collectAllDriverValues();
 
 generateGlobalPowerPinSubGraphs();
 
 generateBusAliasMembers();
 
 PROF_TIMER proc_sub_graph( "ProcessSubGraphs" );
 processSubGraphs();
 
 if( wxLog::IsAllowedTraceMask( DanglingProfileMask ) )
 proc_sub_graph.Show();
 
 // Absorbed subgraphs should no longer be considered
 alg::delete_if( m_driver_subgraphs, [&]( const CONNECTION_SUBGRAPH* candidate ) -> bool
 {
 return candidate->m_absorbed;
 } );
 
 // Store global subgraphs for later reference
 std::vector<CONNECTION_SUBGRAPH*> global_subgraphs;
 std::copy_if( m_driver_subgraphs.begin(), m_driver_subgraphs.end(),
 std::back_inserter( global_subgraphs ),
 [&] ( const CONNECTION_SUBGRAPH* candidate ) -> bool
 {
 return !candidate->m_local_driver;
 } );
 
 // Recache remaining valid subgraphs by sheet path
 m_sheet_to_subgraphs_map.clear();
 
 for( CONNECTION_SUBGRAPH* subgraph : m_driver_subgraphs )
 m_sheet_to_subgraphs_map[ subgraph->m_sheet ].emplace_back( subgraph );
 
 thread_pool& tp = GetKiCadThreadPool();
 
 tp.push_loop( m_driver_subgraphs.size(),
 [&]( const int a, const int b)
 {
 for( int ii = a; ii < b; ++ii )
 m_driver_subgraphs[ii]->UpdateItemConnections();
 });
 tp.wait_for_tasks();
 
 // Next time through the subgraphs, we do some post-processing to handle things like
 // connecting bus members to their neighboring subgraphs, and then propagate connections
 // through the hierarchy
 
 for( CONNECTION_SUBGRAPH* subgraph : m_driver_subgraphs )
 {
 if( !subgraph->m_dirty )
 continue;
 
 wxLogTrace( ConnTrace, wxS( "Processing %lu (%s) for propagation" ), subgraph->m_code,
 subgraph->m_driver_connection->Name() );
 
 // For subgraphs that are driven by a global (power port or label) and have more
 // than one global driver, we need to seek out other subgraphs driven by the
 // same name as the non-chosen driver and update them to match the chosen one.
 
 if( !subgraph->m_local_driver && subgraph->m_multiple_drivers )
 {
 for( SCH_ITEM* driver : subgraph->m_drivers )
 {
 if( driver == subgraph->m_driver )
 continue;
 
 const wxString& secondary_name = subgraph->GetNameForDriver( driver );
 
 if( secondary_name == subgraph->m_driver_connection->Name() )
 continue;
 
 bool secondary_is_global = CONNECTION_SUBGRAPH::GetDriverPriority( driver )
 >= CONNECTION_SUBGRAPH::PRIORITY::POWER_PIN;
 
 for( CONNECTION_SUBGRAPH* candidate : global_subgraphs )
 {
 if( candidate == subgraph )
 continue;
 
 if( !secondary_is_global && candidate->m_sheet != subgraph->m_sheet )
 continue;
 
 SCH_CONNECTION* conn = candidate->m_driver_connection;
 
 if( conn->Name() == secondary_name )
 {
 wxLogTrace( ConnTrace, wxS( "Global %lu (%s) promoted to %s" ), candidate->m_code,
 conn->Name(), subgraph->m_driver_connection->Name() );
 
 conn->Clone( *subgraph->m_driver_connection );
 
 candidate->m_dirty = false;
 propagateToNeighbors( candidate, false );
 }
 }
 }
 }
 
 // This call will handle descending the hierarchy and updating child subgraphs
 propagateToNeighbors( subgraph, false );
 }
 
 // After processing and allowing some to be skipped if they have hierarchical
 // pins connecting both up and down the hierarchy, we check to see if any of them
 // have not been processed. This would indicate that they do not have off-sheet connections
 // but we still need to handle the subgraph
 for( CONNECTION_SUBGRAPH* subgraph : m_driver_subgraphs )
 {
 if( subgraph->m_dirty )
 propagateToNeighbors( subgraph, true );
 }
 
 // Handle buses that have been linked together somewhere by member (net) connections.
 // This feels a bit hacky, perhaps this algorithm should be revisited in the future.
 
 // For net subgraphs that have more than one bus parent, we need to ensure that those
 // buses are linked together in the final netlist. The final name of each bus might not
 // match the local name that was used to establish the parent-child relationship, because
 // the bus may have been renamed by a hierarchical connection. So, for each of these cases,
 // we need to identify the appropriate bus members to link together (and their final names),
 // and then update all instances of the old name in the hierarchy.
 
 for( CONNECTION_SUBGRAPH* subgraph : m_driver_subgraphs )
 {
 // All SGs should have been processed by propagateToNeighbors above
 wxASSERT_MSG( !subgraph->m_dirty, wxS( "Subgraph not processed by propagateToNeighbors!" ) );
 
 if( subgraph->m_bus_parents.size() < 2 )
 continue;
 
 SCH_CONNECTION* conn = subgraph->m_driver_connection;
 
 wxLogTrace( ConnTrace, wxS( "%lu (%s) has multiple bus parents" ),
 subgraph->m_code, conn->Name() );
 
 wxASSERT( conn->IsNet() );
 
 for( const auto& ii : subgraph->m_bus_parents )
 {
 SCH_CONNECTION* link_member = ii.first.get();
 
 for( CONNECTION_SUBGRAPH* parent : ii.second )
 {
 while( parent->m_absorbed )
 parent = parent->m_absorbed_by;
 
 SCH_CONNECTION* match = matchBusMember( parent->m_driver_connection, link_member );
 
 if( !match )
 {
 wxLogTrace( ConnTrace, wxS( "Warning: could not match %s inside %lu (%s)" ),
 conn->Name(), parent->m_code, parent->m_driver_connection->Name() );
 continue;
 }
 
 if( conn->Name() != match->Name() )
 {
 wxString old_name = match->Name();
 
 wxLogTrace( ConnTrace, wxS( "Updating %lu (%s) member %s to %s" ), parent->m_code,
 parent->m_driver_connection->Name(), old_name, conn->Name() );
 
 match->Clone( *conn );
 
 auto jj = m_net_name_to_subgraphs_map.find( old_name );
 
 if( jj == m_net_name_to_subgraphs_map.end() )
 continue;
 
 for( CONNECTION_SUBGRAPH* old_sg : jj->second )
 {
 while( old_sg->m_absorbed )
 old_sg = old_sg->m_absorbed_by;
 
 old_sg->m_driver_connection->Clone( *conn );
 }
 }
 }
 }
 }
 
 
 auto updateItemConnectionsTask =
 [&]( CONNECTION_SUBGRAPH* subgraph ) -> size_t
 {
 // Make sure weakly-driven single-pin nets get the unconnected_ prefix
 if( !subgraph->m_strong_driver && subgraph->m_drivers.size() == 1 &&
 subgraph->m_driver->Type() == SCH_PIN_T )
 {
 SCH_PIN* pin = static_cast<SCH_PIN*>( subgraph->m_driver );
 wxString name = pin->GetDefaultNetName( subgraph->m_sheet, true );
 
 subgraph->m_driver_connection->ConfigureFromLabel( name );
 }
 
 subgraph->m_dirty = false;
 subgraph->UpdateItemConnections();
 
 // No other processing to do on buses
 if( subgraph->m_driver_connection->IsBus() )
 return 0;
 
 // As a visual aid, we can check sheet pins that are driven by themselves to see
 // if they should be promoted to buses
 
 if( subgraph->m_driver && subgraph->m_driver->Type() == SCH_SHEET_PIN_T )
 {
 SCH_SHEET_PIN* pin = static_cast<SCH_SHEET_PIN*>( subgraph->m_driver );
 
 if( SCH_SHEET* sheet = pin->GetParent() )
 {
 wxString pinText = pin->GetText();
 SCH_SCREEN* screen = sheet->GetScreen();
 
 for( SCH_ITEM* item : screen->Items().OfType( SCH_HIER_LABEL_T ) )
 {
 SCH_HIERLABEL* label = static_cast<SCH_HIERLABEL*>( item );
 
 if( label->GetText() == pinText )
 {
 SCH_SHEET_PATH path = subgraph->m_sheet;
 path.push_back( sheet );
 
 SCH_CONNECTION* parent_conn = label->Connection( &path );
 
 if( parent_conn && parent_conn->IsBus() )
 subgraph->m_driver_connection->SetType( CONNECTION_TYPE::BUS );
 
 break;
 }
 }
 
 if( subgraph->m_driver_connection->IsBus() )
 return 0;
 }
 }
 
 return 1;
 };
 
 tp.push_loop( m_driver_subgraphs.size(),
 [&]( const int a, const int b)
 {
 for( int ii = a; ii < b; ++ii )
 updateItemConnectionsTask( m_driver_subgraphs[ii] );
 });
 tp.wait_for_tasks();
 
 m_net_code_to_subgraphs_map.clear();
 m_net_name_to_subgraphs_map.clear();
 
 for( CONNECTION_SUBGRAPH* subgraph : m_driver_subgraphs )
 {
 NET_NAME_CODE_CACHE_KEY key = { subgraph->GetNetName(),
 subgraph->m_driver_connection->NetCode() };
 m_net_code_to_subgraphs_map[ key ].push_back( subgraph );
 
 m_net_name_to_subgraphs_map[subgraph->m_driver_connection->Name()].push_back( subgraph );
 }
 
 std::shared_ptr<NET_SETTINGS>& netSettings = m_schematic->Prj().GetProjectFile().m_NetSettings;
 std::map<wxString, wxString> oldAssignments = netSettings->m_NetClassLabelAssignments;
 
 netSettings->m_NetClassLabelAssignments.clear();
 
 auto dirtySubgraphs =
 [&]( const std::vector<CONNECTION_SUBGRAPH*>& subgraphs )
 {
 if( aChangedItemHandler )
 {
 for( const CONNECTION_SUBGRAPH* subgraph : subgraphs )
 {
 for( SCH_ITEM* item : subgraph->m_items )
 (*aChangedItemHandler)( item );
 }
 }
 };
 
 auto checkNetclassDrivers =
 [&]( const std::vector<CONNECTION_SUBGRAPH*>& subgraphs )
 {
 const CONNECTION_SUBGRAPH* driverSubgraph = nullptr;
 wxString netclass;
 
 wxCHECK_RET( !subgraphs.empty(), wxT("Invalid empty subgraph" ) );
 
 for( const CONNECTION_SUBGRAPH* subgraph : subgraphs )
 {
 for( SCH_ITEM* item : subgraph->m_items )
 {
 netclass = subgraph->GetNetclassForDriver( item );
 
 if( !netclass.IsEmpty() )
 break;
 }
 
 if( !netclass.IsEmpty() )
 {
 driverSubgraph = subgraph;
 break;
 }
 }
 
 if( netclass.IsEmpty() )
 return;
 
 if( !driverSubgraph )
 driverSubgraph = subgraphs.front();
 
 const wxString netname = driverSubgraph->GetNetName();
 
 if( driverSubgraph->m_driver_connection->IsBus() )
 {
 for( const auto& member : driverSubgraph->m_driver_connection->Members() )
 {
 netSettings->m_NetClassLabelAssignments[ member->Name() ] = netclass;
 
 auto ii = m_net_name_to_subgraphs_map.find( member->Name() );
 
 if( ii != m_net_name_to_subgraphs_map.end() )
 dirtySubgraphs( ii->second );
 }
 }
 
 netSettings->m_NetClassLabelAssignments[ netname ] = netclass;
 
 if( oldAssignments[ netname ] != netclass )
 dirtySubgraphs( subgraphs );
 };
 
 for( const auto& [ netname, subgraphs ] : m_net_name_to_subgraphs_map )
 checkNetclassDrivers( subgraphs );
}
 
 
int CONNECTION_GRAPH::getOrCreateNetCode( const wxString& aNetName )
{
 int code;
 
 auto it = m_net_name_to_code_map.find( aNetName );
 
 if( it == m_net_name_to_code_map.end() )
 {
 code = m_last_net_code++;
 m_net_name_to_code_map[ aNetName ] = code;
 }
 else
 {
 code = it->second;
 }
 
 return code;
}
 
 
int CONNECTION_GRAPH::assignNewNetCode( SCH_CONNECTION& aConnection )
{
 int code = getOrCreateNetCode( aConnection.Name() );
 
 aConnection.SetNetCode( code );
 
 return code;
}
 
 
void CONNECTION_GRAPH::assignNetCodesToBus( SCH_CONNECTION* aConnection )
{
 std::vector<std::shared_ptr<SCH_CONNECTION>> connections_to_check( aConnection->Members() );
 
 for( unsigned i = 0; i < connections_to_check.size(); i++ )
 {
 const std::shared_ptr<SCH_CONNECTION>& member = connections_to_check[i];
 
 if( member->IsBus() )
 {
 connections_to_check.insert( connections_to_check.end(),
 member->Members().begin(),
 member->Members().end() );
 continue;
 }
 
 assignNewNetCode( *member );
 }
}
 
 
void CONNECTION_GRAPH::propagateToNeighbors( CONNECTION_SUBGRAPH* aSubgraph, bool aForce )
{
 SCH_CONNECTION* conn = aSubgraph->m_driver_connection;
 std::vector<CONNECTION_SUBGRAPH*> search_list;
 std::unordered_set<CONNECTION_SUBGRAPH*> visited;
 std::unordered_set<SCH_CONNECTION*> stale_bus_members;
 
 auto visit =[&]( CONNECTION_SUBGRAPH* aParent )
 {
 for( SCH_SHEET_PIN* pin : aParent->m_hier_pins )
 {
 SCH_SHEET_PATH path = aParent->m_sheet;
 path.push_back( pin->GetParent() );
 
 auto it = m_sheet_to_subgraphs_map.find( path );
 
 if( it == m_sheet_to_subgraphs_map.end() )
 continue;
 
 for( CONNECTION_SUBGRAPH* candidate : it->second )
 {
 if( !candidate->m_strong_driver
 || candidate->m_hier_ports.empty()
 || visited.count( candidate ) )
 {
 continue;
 }
 
 for( SCH_HIERLABEL* label : candidate->m_hier_ports )
 {
 if( candidate->GetNameForDriver( label ) == aParent->GetNameForDriver( pin ) )
 {
 wxLogTrace( ConnTrace, wxS( "%lu: found child %lu (%s)" ), aParent->m_code,
 candidate->m_code, candidate->m_driver_connection->Name() );
 
 candidate->m_hier_parent = aParent;
 aParent->m_hier_children.insert( candidate );
 
 wxASSERT( candidate->m_graph == aParent->m_graph );
 
 search_list.push_back( candidate );
 break;
 }
 }
 }
 }
 
 for( SCH_HIERLABEL* label : aParent->m_hier_ports )
 {
 SCH_SHEET_PATH path = aParent->m_sheet;
 path.pop_back();
 
 auto it = m_sheet_to_subgraphs_map.find( path );
 
 if( it == m_sheet_to_subgraphs_map.end() )
 continue;
 
 for( CONNECTION_SUBGRAPH* candidate : it->second )
 {
 if( candidate->m_hier_pins.empty()
 || visited.count( candidate )
 || candidate->m_driver_connection->Type() != aParent->m_driver_connection->Type() )
 {
 continue;
 }
 
 const KIID& last_parent_uuid = aParent->m_sheet.Last()->m_Uuid;
 
 for( SCH_SHEET_PIN* pin : candidate->m_hier_pins )
 {
 // If the last sheet UUIDs won't match, no need to check the full path
 if( pin->GetParent()->m_Uuid != last_parent_uuid )
 continue;
 
 SCH_SHEET_PATH pin_path = path;
 pin_path.push_back( pin->GetParent() );
 
 if( pin_path != aParent->m_sheet )
 continue;
 
 if( aParent->GetNameForDriver( label ) == candidate->GetNameForDriver( pin ) )
 {
 wxLogTrace( ConnTrace, wxS( "%lu: found additional parent %lu (%s)" ),
 aParent->m_code, candidate->m_code,
 candidate->m_driver_connection->Name() );
 
 aParent->m_hier_children.insert( candidate );
 search_list.push_back( candidate );
 break;
 }
 }
 }
 }
 };
 
 auto propagate_bus_neighbors = [&]( CONNECTION_SUBGRAPH* aParentGraph )
 {
 for( const auto& kv : aParentGraph->m_bus_neighbors )
 {
 for( CONNECTION_SUBGRAPH* neighbor : kv.second )
 {
 // May have been absorbed but won't have been deleted
 while( neighbor->m_absorbed )
 neighbor = neighbor->m_absorbed_by;
 
 SCH_CONNECTION* parent = aParentGraph->m_driver_connection;
 
 // Now member may be out of date, since we just cloned the
 // connection from higher up in the hierarchy. We need to
 // figure out what the actual new connection is.
 SCH_CONNECTION* member = matchBusMember( parent, kv.first.get() );
 
 if( !member )
 {
 // Try harder: we might match on a secondary driver
 for( CONNECTION_SUBGRAPH* sg : kv.second )
 {
 if( sg->m_multiple_drivers )
 {
 SCH_SHEET_PATH sheet = sg->m_sheet;
 
 for( SCH_ITEM* driver : sg->m_drivers )
 {
 auto c = getDefaultConnection( driver, sg );
 member = matchBusMember( parent, c.get() );
 
 if( member )
 break;
 }
 }
 
 if( member )
 break;
 }
 }
 
 // This is bad, probably an ERC error
 if( !member )
 {
 wxLogTrace( ConnTrace, wxS( "Could not match bus member %s in %s" ),
 kv.first->Name(), parent->Name() );
 continue;
 }
 
 auto neighbor_conn = neighbor->m_driver_connection;
 auto neighbor_name = neighbor_conn->Name();
 
 // Matching name: no update needed
 if( neighbor_name == member->Name() )
 continue;
 
 // Was this neighbor already updated from a different sheet? Don't rename it again
 if( neighbor_conn->Sheet() != neighbor->m_sheet )
 continue;
 
 // Safety check against infinite recursion
 wxASSERT( neighbor_conn->IsNet() );
 
 wxLogTrace( ConnTrace, wxS( "%lu (%s) connected to bus member %s (local %s)" ),
 neighbor->m_code, neighbor_name, member->Name(), member->LocalName() );
 
 // Take whichever name is higher priority
 if( CONNECTION_SUBGRAPH::GetDriverPriority( neighbor->m_driver )
 >= CONNECTION_SUBGRAPH::PRIORITY::POWER_PIN )
 {
 member->Clone( *neighbor_conn );
 stale_bus_members.insert( member );
 }
 else
 {
 neighbor_conn->Clone( *member );
 
 recacheSubgraphName( neighbor, neighbor_name );
 
 // Recurse onto this neighbor in case it needs to re-propagate
 neighbor->m_dirty = true;
 propagateToNeighbors( neighbor, aForce );
 }
 }
 }
 };
 
 // If we are a bus, we must propagate to local neighbors and then the hierarchy
 if( conn->IsBus() )
 propagate_bus_neighbors( aSubgraph );
 
 // If we have both ports and pins, skip processing as we'll be visited by a parent or child.
 // If we only have one or the other, process (we can either go bottom-up or top-down depending
 // on which subgraph comes up first)
 if( !aForce && !aSubgraph->m_hier_ports.empty() && !aSubgraph->m_hier_pins.empty() )
 {
 wxLogTrace( ConnTrace, wxS( "%lu (%s) has both hier ports and pins; deferring processing" ),
 aSubgraph->m_code, conn->Name() );
 return;
 }
 else if( aSubgraph->m_hier_ports.empty() && aSubgraph->m_hier_pins.empty() )
 {
 wxLogTrace( ConnTrace, wxS( "%lu (%s) has no hier pins or ports on sheet %s; marking clean" ),
 aSubgraph->m_code, conn->Name(), aSubgraph->m_sheet.PathHumanReadable() );
 aSubgraph->m_dirty = false;
 return;
 }
 
 visited.insert( aSubgraph );
 
 wxLogTrace( ConnTrace, wxS( "Propagating %lu (%s) to subsheets" ),
 aSubgraph->m_code, aSubgraph->m_driver_connection->Name() );
 
 visit( aSubgraph );
 
 for( unsigned i = 0; i < search_list.size(); i++ )
 {
 auto child = search_list[i];
 
 if( visited.insert( child ).second )
 visit( child );
 
 child->m_dirty = false;
 }
 
 // Now, find the best driver for this chain of subgraphs
 CONNECTION_SUBGRAPH* bestDriver = aSubgraph;
 CONNECTION_SUBGRAPH::PRIORITY highest =
 CONNECTION_SUBGRAPH::GetDriverPriority( aSubgraph->m_driver );
 bool bestIsStrong = ( highest >= CONNECTION_SUBGRAPH::PRIORITY::HIER_LABEL );
 wxString bestName = aSubgraph->m_driver_connection->Name();
 
 // Check if a subsheet has a higher-priority connection to the same net
 if( highest < CONNECTION_SUBGRAPH::PRIORITY::POWER_PIN )
 {
 for( CONNECTION_SUBGRAPH* subgraph : visited )
 {
 if( subgraph == aSubgraph )
 continue;
 
 CONNECTION_SUBGRAPH::PRIORITY priority =
 CONNECTION_SUBGRAPH::GetDriverPriority( subgraph->m_driver );
 
 bool candidateStrong = ( priority >= CONNECTION_SUBGRAPH::PRIORITY::HIER_LABEL );
 wxString candidateName = subgraph->m_driver_connection->Name();
 bool shorterPath = subgraph->m_sheet.size() < bestDriver->m_sheet.size();
 bool asGoodPath = subgraph->m_sheet.size() <= bestDriver->m_sheet.size();
 
 // Pick a better driving subgraph if it:
 // a) has a power pin or global driver
 // b) is a strong driver and we're a weak driver
 // c) is a higher priority strong driver
 // d) matches our priority, is a strong driver, and has a shorter path
 // e) matches our strength and is at least as short, and is alphabetically lower
 
 if( ( priority >= CONNECTION_SUBGRAPH::PRIORITY::POWER_PIN ) ||
 ( !bestIsStrong && candidateStrong ) ||
 ( priority > highest && candidateStrong ) ||
 ( priority == highest && candidateStrong && shorterPath ) ||
 ( ( bestIsStrong == candidateStrong ) && asGoodPath && ( priority == highest ) &&
 ( candidateName < bestName ) ) )
 {
 bestDriver = subgraph;
 highest = priority;
 bestIsStrong = candidateStrong;
 bestName = candidateName;
 }
 }
 }
 
 if( bestDriver != aSubgraph )
 {
 wxLogTrace( ConnTrace, wxS( "%lu (%s) overridden by new driver %lu (%s)" ),
 aSubgraph->m_code, aSubgraph->m_driver_connection->Name(), bestDriver->m_code,
 bestDriver->m_driver_connection->Name() );
 }
 
 conn = bestDriver->m_driver_connection;
 
 for( CONNECTION_SUBGRAPH* subgraph : visited )
 {
 wxString old_name = subgraph->m_driver_connection->Name();
 
 subgraph->m_driver_connection->Clone( *conn );
 
 if( old_name != conn->Name() )
 recacheSubgraphName( subgraph, old_name );
 
 if( conn->IsBus() )
 propagate_bus_neighbors( subgraph );
 }
 
 // Somewhere along the way, a bus member may have been upgraded to a global or power label.
 // Because this can happen anywhere, we need a second pass to update all instances of that bus
 // member to have the correct connection info
 if( conn->IsBus() && !stale_bus_members.empty() )
 {
 std::unordered_set<SCH_CONNECTION*> cached_members = stale_bus_members;
 
 for( SCH_CONNECTION* stale_member : cached_members )
 {
 for( CONNECTION_SUBGRAPH* subgraph : visited )
 {
 SCH_CONNECTION* member = matchBusMember( subgraph->m_driver_connection,
 stale_member );
 
 if( !member )
 {
 wxLogTrace( ConnTrace, wxS( "WARNING: failed to match stale member %s in %s." ),
 stale_member->Name(), subgraph->m_driver_connection->Name() );
 continue;
 }
 
 wxLogTrace( ConnTrace, wxS( "Updating %lu (%s) member %s to %s" ), subgraph->m_code,
 subgraph->m_driver_connection->Name(), member->LocalName(),
 stale_member->Name() );
 
 member->Clone( *stale_member );
 
 propagate_bus_neighbors( subgraph );
 }
 }
 }
 
 aSubgraph->m_dirty = false;
}
 
 
std::shared_ptr<SCH_CONNECTION> CONNECTION_GRAPH::getDefaultConnection( SCH_ITEM* aItem,
 CONNECTION_SUBGRAPH* aSubgraph )
{
 std::shared_ptr<SCH_CONNECTION> c = std::shared_ptr<SCH_CONNECTION>( nullptr );
 
 switch( aItem->Type() )
 {
 case SCH_PIN_T:
 {
 SCH_PIN* pin = static_cast<SCH_PIN*>( aItem );
 
 if( pin->IsGlobalPower() )
 c = std::make_shared<SCH_CONNECTION>( aItem, aSubgraph->m_sheet );
 
 break;
 }
 
 case SCH_GLOBAL_LABEL_T:
 case SCH_HIER_LABEL_T:
 case SCH_LABEL_T:
 {
 c = std::make_shared<SCH_CONNECTION>( aItem, aSubgraph->m_sheet );
 break;
 }
 
 default:
 break;
 }
 
 if( c )
 {
 c->SetGraph( this );
 c->ConfigureFromLabel( aSubgraph->GetNameForDriver( aItem ) );
 }
 
 return c;
}
 
 
SCH_CONNECTION* CONNECTION_GRAPH::matchBusMember( SCH_CONNECTION* aBusConnection,
 SCH_CONNECTION* aSearch )
{
 wxASSERT( aBusConnection->IsBus() );
 
 SCH_CONNECTION* match = nullptr;
 
 if( aBusConnection->Type() == CONNECTION_TYPE::BUS )
 {
 // Vector bus: compare against index, because we allow the name
 // to be different
 
 for( const std::shared_ptr<SCH_CONNECTION>& bus_member : aBusConnection->Members() )
 {
 if( bus_member->VectorIndex() == aSearch->VectorIndex() )
 {
 match = bus_member.get();
 break;
 }
 }
 }
 else
 {
 // Group bus
 for( const std::shared_ptr<SCH_CONNECTION>& c : aBusConnection->Members() )
 {
 // Vector inside group: compare names, because for bus groups
 // we expect the naming to be consistent across all usages
 // TODO(JE) explain this in the docs
 if( c->Type() == CONNECTION_TYPE::BUS )
 {
 for( const std::shared_ptr<SCH_CONNECTION>& bus_member : c->Members() )
 {
 if( bus_member->LocalName() == aSearch->LocalName() )
 {
 match = bus_member.get();
 break;
 }
 }
 }
 else if( c->LocalName() == aSearch->LocalName() )
 {
 match = c.get();
 break;
 }
 }
 }
 
 return match;
}
 
 
void CONNECTION_GRAPH::recacheSubgraphName( CONNECTION_SUBGRAPH* aSubgraph,
 const wxString& aOldName )
{
 auto it = m_net_name_to_subgraphs_map.find( aOldName );
 
 if( it != m_net_name_to_subgraphs_map.end() )
 {
 std::vector<CONNECTION_SUBGRAPH*>& vec = it->second;
 alg::delete_matching( vec, aSubgraph );
 }
 
 wxLogTrace( ConnTrace, wxS( "recacheSubgraphName: %s => %s" ), aOldName,
 aSubgraph->m_driver_connection->Name() );
 
 m_net_name_to_subgraphs_map[aSubgraph->m_driver_connection->Name()].push_back( aSubgraph );
}
 
 
std::shared_ptr<BUS_ALIAS> CONNECTION_GRAPH::GetBusAlias( const wxString& aName )
{
 auto it = m_bus_alias_cache.find( aName );
 
 return it != m_bus_alias_cache.end() ? it->second : nullptr;
}
 
 
std::vector<const CONNECTION_SUBGRAPH*> CONNECTION_GRAPH::GetBusesNeedingMigration()
{
 std::vector<const CONNECTION_SUBGRAPH*> ret;
 
 for( CONNECTION_SUBGRAPH* subgraph : m_subgraphs )
 {
 // Graph is supposed to be up-to-date before calling this
 wxASSERT( !subgraph->m_dirty );
 
 if( !subgraph->m_driver )
 continue;
 
 SCH_CONNECTION* connection = subgraph->m_driver->Connection( &subgraph->m_sheet );
 
 if( !connection->IsBus() )
 continue;
 
 auto labels = subgraph->GetVectorBusLabels();
 
 if( labels.size() > 1 )
 {
 bool different = false;
 wxString first = static_cast<SCH_TEXT*>( labels.at( 0 ) )->GetShownText( false );
 
 for( unsigned i = 1; i < labels.size(); ++i )
 {
 if( static_cast<SCH_TEXT*>( labels.at( i ) )->GetShownText( false ) != first )
 {
 different = true;
 break;
 }
 }
 
 if( !different )
 continue;
 
 wxLogTrace( ConnTrace, wxS( "SG %ld (%s) has multiple bus labels" ), subgraph->m_code,
 connection->Name() );
 
 ret.push_back( subgraph );
 }
 }
 
 return ret;
}
 
 
wxString CONNECTION_GRAPH::GetResolvedSubgraphName( const CONNECTION_SUBGRAPH* aSubGraph ) const
{
 wxString retval = aSubGraph->GetNetName();
 bool found = false;
 
 // This is a hacky way to find the true subgraph net name (why do we not store it?)
 // TODO: Remove once the actual netname of the subgraph is stored with the subgraph
 
 for( auto it = m_net_name_to_subgraphs_map.begin(); it != m_net_name_to_subgraphs_map.end() && !found; ++it )
 {
 for( CONNECTION_SUBGRAPH* graph : it->second )
 {
 if( graph == aSubGraph )
 {
 retval = it->first;
 found = true;
 break;
 }
 }
 }
 
 return retval;
}
 
 
CONNECTION_SUBGRAPH* CONNECTION_GRAPH::FindSubgraphByName( const wxString& aNetName,
 const SCH_SHEET_PATH& aPath )
{
 auto it = m_net_name_to_subgraphs_map.find( aNetName );
 
 if( it == m_net_name_to_subgraphs_map.end() )
 return nullptr;
 
 for( CONNECTION_SUBGRAPH* sg : it->second )
 {
 // Cache is supposed to be valid by now
 wxASSERT( sg && !sg->m_absorbed && sg->m_driver_connection );
 
 if( sg->m_sheet == aPath && sg->m_driver_connection->Name() == aNetName )
 return sg;
 }
 
 return nullptr;
}
 
 
CONNECTION_SUBGRAPH* CONNECTION_GRAPH::FindFirstSubgraphByName( const wxString& aNetName )
{
 auto it = m_net_name_to_subgraphs_map.find( aNetName );
 
 if( it == m_net_name_to_subgraphs_map.end() )
 return nullptr;
 
 wxASSERT( !it->second.empty() );
 
 return it->second[0];
}
 
 
CONNECTION_SUBGRAPH* CONNECTION_GRAPH::GetSubgraphForItem( SCH_ITEM* aItem )
{
 auto it = m_item_to_subgraph_map.find( aItem );
 CONNECTION_SUBGRAPH* ret = it != m_item_to_subgraph_map.end() ? it->second : nullptr;
 
 while( ret && ret->m_absorbed )
 ret = ret->m_absorbed_by;
 
 return ret;
}
 
 
const std::vector<CONNECTION_SUBGRAPH*> CONNECTION_GRAPH::GetAllSubgraphs(
 const wxString& aNetName ) const
{
 std::vector<CONNECTION_SUBGRAPH*> subgraphs;
 
 auto it = m_net_name_to_subgraphs_map.find( aNetName );
 
 if( it == m_net_name_to_subgraphs_map.end() )
 return subgraphs;
 
 return it->second;
}
 
 
int CONNECTION_GRAPH::RunERC()
{
 int error_count = 0;
 
 wxCHECK_MSG( m_schematic, true, wxS( "Null m_schematic in CONNECTION_GRAPH::RunERC" ) );
 
 ERC_SETTINGS& settings = m_schematic->ErcSettings();
 
 // We don't want to run many ERC checks more than once on a given screen even though it may
 // represent multiple sheets with multiple subgraphs. We can tell these apart by drivers.
 std::set<SCH_ITEM*> seenDriverInstances;
 
 for( CONNECTION_SUBGRAPH* subgraph : m_subgraphs )
 {
 // There shouldn't be any null sub-graph pointers.
 wxCHECK2( subgraph, continue );
 
 // Graph is supposed to be up-to-date before calling RunERC()
 wxASSERT( !subgraph->m_dirty );
 
 if( subgraph->m_absorbed )
 continue;
 
 if( seenDriverInstances.count( subgraph->m_driver ) )
 continue;
 
 if( subgraph->m_driver )
 seenDriverInstances.insert( subgraph->m_driver );
 
 if( settings.IsTestEnabled( ERCE_DRIVER_CONFLICT ) )
 {
 if( !ercCheckMultipleDrivers( subgraph ) )
 error_count++;
 }
 
 subgraph->ResolveDrivers( false );
 
 if( settings.IsTestEnabled( ERCE_BUS_TO_NET_CONFLICT ) )
 {
 if( !ercCheckBusToNetConflicts( subgraph ) )
 error_count++;
 }
 
 if( settings.IsTestEnabled( ERCE_BUS_ENTRY_CONFLICT ) )
 {
 if( !ercCheckBusToBusEntryConflicts( subgraph ) )
 error_count++;
 }
 
 if( settings.IsTestEnabled( ERCE_BUS_TO_BUS_CONFLICT ) )
 {
 if( !ercCheckBusToBusConflicts( subgraph ) )
 error_count++;
 }
 
 if( settings.IsTestEnabled( ERCE_WIRE_DANGLING ) )
 {
 if( !ercCheckFloatingWires( subgraph ) )
 error_count++;
 }
 
 if( settings.IsTestEnabled( ERCE_NOCONNECT_CONNECTED )
 || settings.IsTestEnabled( ERCE_NOCONNECT_NOT_CONNECTED )
 || settings.IsTestEnabled( ERCE_PIN_NOT_CONNECTED ) )
 {
 if( !ercCheckNoConnects( subgraph ) )
 error_count++;
 }
 
 if( settings.IsTestEnabled( ERCE_LABEL_NOT_CONNECTED )
 || settings.IsTestEnabled( ERCE_GLOBLABEL ) )
 {
 if( !ercCheckLabels( subgraph ) )
 error_count++;
 }
 }
 
 // Hierarchical sheet checking is done at the schematic level
 if( settings.IsTestEnabled( ERCE_HIERACHICAL_LABEL )
 || settings.IsTestEnabled( ERCE_PIN_NOT_CONNECTED ) )
 {
 error_count += ercCheckHierSheets();
 }
 
 if( settings.IsTestEnabled( ERCE_NETCLASS_CONFLICT ) )
 {
 for( const auto& [ netname, subgraphs ] : m_net_name_to_subgraphs_map )
 {
 if( !ercCheckNetclassConflicts( subgraphs ) )
 error_count++;
 }
 }
 
 return error_count;
}
 
 
bool CONNECTION_GRAPH::ercCheckMultipleDrivers( const CONNECTION_SUBGRAPH* aSubgraph )
{
 wxCHECK( aSubgraph, false );
 
 if( aSubgraph->m_multiple_drivers )
 {
 for( SCH_ITEM* driver : aSubgraph->m_drivers )
 {
 if( driver == aSubgraph->m_driver )
 continue;
 
 if( driver->Type() == SCH_GLOBAL_LABEL_T
 || driver->Type() == SCH_HIER_LABEL_T
 || driver->Type() == SCH_LABEL_T
 || ( driver->Type() == SCH_PIN_T
 && static_cast<SCH_PIN*>( driver )->IsGlobalPower() ) )
 {
 const wxString& primaryName = aSubgraph->GetNameForDriver( aSubgraph->m_driver );
 const wxString& secondaryName = aSubgraph->GetNameForDriver( driver );
 
 if( primaryName == secondaryName )
 continue;
 
 wxString msg = wxString::Format( _( "Both %s and %s are attached to the same "
 "items; %s will be used in the netlist" ),
 primaryName, secondaryName, primaryName );
 
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_DRIVER_CONFLICT );
 ercItem->SetItems( aSubgraph->m_driver, driver );
 ercItem->SetErrorMessage( msg );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, driver->GetPosition() );
 aSubgraph->m_sheet.LastScreen()->Append( marker );
 
 return false;
 }
 }
 }
 
 return true;
}
 
 
bool CONNECTION_GRAPH::ercCheckNetclassConflicts( const std::vector<CONNECTION_SUBGRAPH*>& subgraphs )
{
 wxString firstNetclass;
 SCH_ITEM* firstNetclassDriver = nullptr;
 
 for( const CONNECTION_SUBGRAPH* subgraph : subgraphs )
 {
 for( SCH_ITEM* item : subgraph->m_items )
 {
 const wxString netclass = subgraph->GetNetclassForDriver( item );
 
 if( netclass.IsEmpty() )
 continue;
 
 if( netclass != firstNetclass )
 {
 if( !firstNetclassDriver )
 {
 firstNetclass = netclass;
 firstNetclassDriver = item;
 continue;
 }
 
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_NETCLASS_CONFLICT );
 ercItem->SetItems( firstNetclassDriver, item );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, item->GetPosition() );
 subgraph->m_sheet.LastScreen()->Append( marker );
 
 return false;
 }
 }
 }
 
 return true;
}
 
 
bool CONNECTION_GRAPH::ercCheckBusToNetConflicts( const CONNECTION_SUBGRAPH* aSubgraph )
{
 const SCH_SHEET_PATH& sheet = aSubgraph->m_sheet;
 SCH_SCREEN* screen = sheet.LastScreen();
 
 SCH_ITEM* net_item = nullptr;
 SCH_ITEM* bus_item = nullptr;
 SCH_CONNECTION conn( this );
 
 for( SCH_ITEM* item : aSubgraph->m_items )
 {
 switch( item->Type() )
 {
 case SCH_LINE_T:
 {
 if( item->GetLayer() == LAYER_BUS )
 bus_item = ( !bus_item ) ? item : bus_item;
 else
 net_item = ( !net_item ) ? item : net_item;
 break;
 }
 
 case SCH_LABEL_T:
 case SCH_GLOBAL_LABEL_T:
 case SCH_SHEET_PIN_T:
 case SCH_HIER_LABEL_T:
 {
 SCH_TEXT* text = static_cast<SCH_TEXT*>( item );
 conn.ConfigureFromLabel( EscapeString( text->GetShownText( false ), CTX_NETNAME ) );
 
 if( conn.IsBus() )
 bus_item = ( !bus_item ) ? item : bus_item;
 else
 net_item = ( !net_item ) ? item : net_item;
 break;
 }
 
 default:
 break;
 }
 }
 
 if( net_item && bus_item )
 {
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_BUS_TO_NET_CONFLICT );
 ercItem->SetItems( net_item, bus_item );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, net_item->GetPosition() );
 screen->Append( marker );
 
 return false;
 }
 
 return true;
}
 
 
bool CONNECTION_GRAPH::ercCheckBusToBusConflicts( const CONNECTION_SUBGRAPH* aSubgraph )
{
 const SCH_SHEET_PATH& sheet = aSubgraph->m_sheet;
 SCH_SCREEN* screen = sheet.LastScreen();
 
 SCH_ITEM* label = nullptr;
 SCH_ITEM* port = nullptr;
 
 for( SCH_ITEM* item : aSubgraph->m_items )
 {
 switch( item->Type() )
 {
 case SCH_TEXT_T:
 case SCH_GLOBAL_LABEL_T:
 {
 if( !label && item->Connection( &sheet )->IsBus() )
 label = item;
 break;
 }
 
 case SCH_SHEET_PIN_T:
 case SCH_HIER_LABEL_T:
 {
 if( !port && item->Connection( &sheet )->IsBus() )
 port = item;
 break;
 }
 
 default:
 break;
 }
 }
 
 if( label && port )
 {
 bool match = false;
 
 for( const auto& member : label->Connection( &sheet )->Members() )
 {
 for( const auto& test : port->Connection( &sheet )->Members() )
 {
 if( test != member && member->Name() == test->Name() )
 {
 match = true;
 break;
 }
 }
 
 if( match )
 break;
 }
 
 if( !match )
 {
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_BUS_TO_BUS_CONFLICT );
 ercItem->SetItems( label, port );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, label->GetPosition() );
 screen->Append( marker );
 
 return false;
 }
 }
 
 return true;
}
 
 
bool CONNECTION_GRAPH::ercCheckBusToBusEntryConflicts( const CONNECTION_SUBGRAPH* aSubgraph )
{
 bool conflict = false;
 const SCH_SHEET_PATH& sheet = aSubgraph->m_sheet;
 SCH_SCREEN* screen = sheet.LastScreen();
 
 SCH_BUS_WIRE_ENTRY* bus_entry = nullptr;
 SCH_ITEM* bus_wire = nullptr;
 wxString bus_name;
 
 if( !aSubgraph->m_driver_connection )
 {
 // Incomplete bus entry. Let the unconnected tests handle it.
 return true;
 }
 
 for( SCH_ITEM* item : aSubgraph->m_items )
 {
 switch( item->Type() )
 {
 case SCH_BUS_WIRE_ENTRY_T:
 {
 if( !bus_entry )
 bus_entry = static_cast<SCH_BUS_WIRE_ENTRY*>( item );
 break;
 }
 
 default:
 break;
 }
 }
 
 if( bus_entry && bus_entry->m_connected_bus_item )
 {
 bus_wire = bus_entry->m_connected_bus_item;
 
 wxASSERT( bus_wire->Type() == SCH_LINE_T );
 
 // In some cases, the connection list (SCH_CONNECTION*) can be null.
 // Skip null connections.
 if( bus_entry->Connection( &sheet )
 && bus_wire->Type() == SCH_LINE_T
 && bus_wire->Connection( &sheet ) )
 {
 conflict = true; // Assume a conflict; we'll reset if we find it's OK
 
 bus_name = bus_wire->Connection( &sheet )->Name();
 
 std::set<wxString> test_names;
 test_names.insert( bus_entry->Connection( &sheet )->Name() );
 
 wxString baseName = sheet.PathHumanReadable();
 
 for( SCH_ITEM* driver : aSubgraph->m_drivers )
 test_names.insert( baseName + aSubgraph->GetNameForDriver( driver ) );
 
 for( const auto& member : bus_wire->Connection( &sheet )->Members() )
 {
 if( member->Type() == CONNECTION_TYPE::BUS )
 {
 for( const auto& sub_member : member->Members() )
 {
 if( test_names.count( sub_member->Name() ) )
 conflict = false;
 }
 }
 else if( test_names.count( member->Name() ) )
 {
 conflict = false;
 }
 }
 }
 }
 
 // Don't report warnings if this bus member has been overridden by a higher priority power pin
 // or global label
 if( conflict && CONNECTION_SUBGRAPH::GetDriverPriority( aSubgraph->m_driver )
 >= CONNECTION_SUBGRAPH::PRIORITY::POWER_PIN )
 {
 conflict = false;
 }
 
 if( conflict )
 {
 wxString netName = aSubgraph->m_driver_connection->Name();
 wxString msg = wxString::Format( _( "Net %s is graphically connected to bus %s but is not a"
 " member of that bus" ),
 UnescapeString( netName ),
 UnescapeString( bus_name ) );
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_BUS_ENTRY_CONFLICT );
 ercItem->SetItems( bus_entry, bus_wire );
 ercItem->SetErrorMessage( msg );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, bus_entry->GetPosition() );
 screen->Append( marker );
 
 return false;
 }
 
 return true;
}
 
 
// TODO(JE) Check sheet pins here too?
bool CONNECTION_GRAPH::ercCheckNoConnects( const CONNECTION_SUBGRAPH* aSubgraph )
{
 ERC_SETTINGS& settings = m_schematic->ErcSettings();
 const SCH_SHEET_PATH& sheet = aSubgraph->m_sheet;
 SCH_SCREEN* screen = sheet.LastScreen();
 bool ok = true;
 SCH_PIN* pin = nullptr;
 
 std::set<SCH_PIN*> unique_pins;
 std::set<SCH_LABEL_BASE*> unique_labels;
 
 wxString netName = GetResolvedSubgraphName( aSubgraph );
 
 auto process_subgraph = [&]( const CONNECTION_SUBGRAPH* aProcessGraph )
 {
 // Any subgraph that contains a no-connect should not
 // more than one pin (which would indicate it is connected
 
 for( SCH_ITEM* item : aProcessGraph->m_items )
 {
 switch( item->Type() )
 {
 case SCH_PIN_T:
 {
 SCH_PIN* test_pin = static_cast<SCH_PIN*>( item );
 
 // Only link NC to pin on the current subgraph being checked
 if( aProcessGraph == aSubgraph )
 pin = test_pin;
 
 if( std::none_of( unique_pins.begin(), unique_pins.end(),
 [test_pin]( SCH_PIN* aPin )
 {
 return test_pin->IsStacked( aPin );
 }
 ))
 {
 unique_pins.insert( test_pin );
 }
 
 break;
 }
 
 case SCH_LABEL_T:
 case SCH_GLOBAL_LABEL_T:
 case SCH_HIER_LABEL_T:
 unique_labels.insert( static_cast<SCH_LABEL_BASE*>( item ) );
 KI_FALLTHROUGH;
 default:
 break;
 }
 }
 };
 
 auto it = m_net_name_to_subgraphs_map.find( netName );
 
 if( it != m_net_name_to_subgraphs_map.end() )
 {
 for( const CONNECTION_SUBGRAPH* subgraph : it->second )
 {
 process_subgraph( subgraph );
 }
 }
 else
 {
 process_subgraph( aSubgraph );
 }
 
 if( aSubgraph->m_no_connect != nullptr )
 {
 if( unique_pins.size() > 1 && settings.IsTestEnabled( ERCE_NOCONNECT_CONNECTED ) )
 {
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_NOCONNECT_CONNECTED );
 VECTOR2I pos;
 
 if( pin )
 {
 ercItem->SetItems( pin, aSubgraph->m_no_connect );
 pos = pin->GetTransformedPosition();
 }
 else
 {
 ercItem->SetItems( aSubgraph->m_no_connect );
 pos = aSubgraph->m_no_connect->GetPosition();
 }
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, pos );
 screen->Append( marker );
 
 ok = false;
 }
 
 if( unique_pins.empty() && unique_labels.empty() && settings.IsTestEnabled( ERCE_NOCONNECT_NOT_CONNECTED ) )
 {
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_NOCONNECT_NOT_CONNECTED );
 ercItem->SetItems( aSubgraph->m_no_connect );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, aSubgraph->m_no_connect->GetPosition() );
 screen->Append( marker );
 
 ok = false;
 }
 }
 else
 {
 bool has_other_connections = false;
 std::vector<SCH_PIN*> pins;
 
 // Any subgraph that lacks a no-connect and contains a pin should also
 // contain at least one other potential driver
 
 for( SCH_ITEM* item : aSubgraph->m_items )
 {
 switch( item->Type() )
 {
 case SCH_PIN_T:
 {
 // Stacked pins do not count as other connections but non-stacked pins do
 if( !has_other_connections && !pins.empty() )
 {
 SCH_PIN* test_pin = static_cast<SCH_PIN*>( item );
 
 for( SCH_PIN* other_pin : pins )
 {
 if( !test_pin->IsStacked( other_pin ) )
 {
 has_other_connections = true;
 break;
 }
 }
 }
 
 pins.emplace_back( static_cast<SCH_PIN*>( item ) );
 
 break;
 }
 
 default:
 if( aSubgraph->GetDriverPriority( item ) != CONNECTION_SUBGRAPH::PRIORITY::NONE )
 has_other_connections = true;
 
 break;
 }
 }
 
 // For many checks, we can just use the first pin
 pin = pins.empty() ? nullptr : pins[0];
 
 // But if there is a power pin, it might be connected elsewhere
 for( SCH_PIN* test_pin : pins )
 {
 if( test_pin->GetType() == ELECTRICAL_PINTYPE::PT_POWER_IN )
 {
 pin = test_pin;
 break;
 }
 }
 
 // Check if power input pins connect to anything else via net name,
 // but not for power symbols (with visible or legacy invisible pins).
 // We want to throw unconnected errors for power symbols even if they are connected to other
 // net items by name, because usually failing to connect them graphically is a mistake
 if( pin && !has_other_connections
 && pin->IsGlobalPower()
 && !pin->GetLibPin()->GetParent()->IsPower() )
 {
 wxString name = pin->Connection( &sheet )->Name();
 wxString local_name = pin->Connection( &sheet )->Name( true );
 
 if( m_global_label_cache.count( name )
 || m_local_label_cache.count( std::make_pair( sheet, local_name ) ) )
 {
 has_other_connections = true;
 }
 }
 
 // Only one pin, and it's not a no-connect pin
 if( pin && !has_other_connections
 && pin->GetType() != ELECTRICAL_PINTYPE::PT_NC
 && pin->GetType() != ELECTRICAL_PINTYPE::PT_NIC
 && settings.IsTestEnabled( ERCE_PIN_NOT_CONNECTED ) )
 {
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_PIN_NOT_CONNECTED );
 ercItem->SetItems( pin );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, pin->GetTransformedPosition() );
 screen->Append( marker );
 
 ok = false;
 }
 
 // If there are multiple pins in this SG, they might be indirectly connected (by netname)
 // rather than directly connected (by wires). We want to flag dangling pins even if they
 // join nets with another pin, as it's often a mistake
 if( pins.size() > 1 )
 {
 for( SCH_PIN* testPin : pins )
 {
 // We only apply this test to power symbols, because other symbols have
 // pins that are meant to be dangling, but the power symbols have pins
 // that are *not* meant to be dangling.
 if( testPin->GetLibPin()->GetParent()->IsPower()
 && testPin->ConnectedItems( sheet ).empty()
 && settings.IsTestEnabled( ERCE_PIN_NOT_CONNECTED ) )
 {
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_PIN_NOT_CONNECTED );
 ercItem->SetItems( testPin );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem,
 testPin->GetTransformedPosition() );
 screen->Append( marker );
 
 ok = false;
 }
 }
 }
 }
 
 return ok;
}
 
 
bool CONNECTION_GRAPH::ercCheckFloatingWires( const CONNECTION_SUBGRAPH* aSubgraph )
{
 if( aSubgraph->m_driver )
 return true;
 
 std::vector<SCH_ITEM*> wires;
 
 // We've gotten this far, so we know we have no valid driver. All we need to do is check
 // for a wire that we can place the error on.
 
 for( SCH_ITEM* item : aSubgraph->m_items )
 {
 if( item->Type() == SCH_LINE_T && item->GetLayer() == LAYER_WIRE )
 wires.emplace_back( item );
 else if( item->Type() == SCH_BUS_WIRE_ENTRY_T )
 wires.emplace_back( item );
 }
 
 if( !wires.empty() )
 {
 SCH_SCREEN* screen = aSubgraph->m_sheet.LastScreen();
 
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_WIRE_DANGLING );
 ercItem->SetItems( wires[0],
 wires.size() > 1 ? wires[1] : nullptr,
 wires.size() > 2 ? wires[2] : nullptr,
 wires.size() > 3 ? wires[3] : nullptr );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, wires[0]->GetPosition() );
 screen->Append( marker );
 
 return false;
 }
 
 return true;
}
 
 
bool CONNECTION_GRAPH::ercCheckLabels( const CONNECTION_SUBGRAPH* aSubgraph )
{
 // Label connection rules:
 // Any label without a no-connect needs to have at least 2 pins, otherwise it is invalid
 // Local labels are flagged if they don't connect to any pins and don't have a no-connect
 // Global labels are flagged if they appear only once, don't connect to any local labels,
 // and don't have a no-connect marker
 
 
 if( !aSubgraph->m_driver_connection )
 return true;
 
 // Buses are excluded from this test: many users create buses with only a single instance
 // and it's not really a problem as long as the nets in the bus pass ERC
 if( aSubgraph->m_driver_connection->IsBus() )
 return true;
 
 ERC_SETTINGS& settings = m_schematic->ErcSettings();
 bool ok = true;
 int pinCount = 0;
 bool has_nc = !!aSubgraph->m_no_connect;
 
 std::map<KICAD_T, std::vector<SCH_TEXT*>> label_map;
 
 
 auto hasPins =
 []( const CONNECTION_SUBGRAPH* aLocSubgraph ) -> int
 {
 return
 std::count_if( aLocSubgraph->m_items.begin(), aLocSubgraph->m_items.end(), []( const SCH_ITEM* item )
 { return item->Type() == SCH_PIN_T; } );
 };
 
 auto reportError = [&]( SCH_TEXT* aText, int errCode )
 {
 if( settings.IsTestEnabled( errCode ) )
 {
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( errCode );
 ercItem->SetItems( aText );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, aText->GetPosition() );
 aSubgraph->m_sheet.LastScreen()->Append( marker );
 }
 };
 
 pinCount = hasPins( aSubgraph );
 
 for( SCH_ITEM* item : aSubgraph->m_items )
 {
 switch( item->Type() )
 {
 case SCH_LABEL_T:
 case SCH_GLOBAL_LABEL_T:
 case SCH_HIER_LABEL_T:
 {
 SCH_TEXT* text = static_cast<SCH_TEXT*>( item );
 
 label_map[item->Type()].push_back( text );
 
 // Below, we'll create an ERC if the whole subgraph is unconnected. But, additionally,
 // we want to error if an individual label in the subgraph is floating, even if it's
 // connected to other valid things by way of another label on the same sheet.
 if( text->IsDangling() )
 {
 reportError( text, ERCE_LABEL_NOT_CONNECTED );
 return false;
 }
 
 break;
 }
 
 default:
 break;
 }
 }
 
 if( label_map.empty() )
 return true;
 
 wxString netName = GetResolvedSubgraphName( aSubgraph );
 
 wxCHECK_MSG( m_schematic, true, wxS( "Null m_schematic in CONNECTION_GRAPH::ercCheckLabels" ) );
 
 // Labels that have multiple pins connected are not dangling (may be used for naming segments)
 // so leave them without errors here
 if( pinCount > 1 )
 return true;
 
 for( auto& [type, label_vec] : label_map )
 {
 
 switch( type )
 {
 case SCH_GLOBAL_LABEL_T:
 if( !settings.IsTestEnabled( ERCE_GLOBLABEL ) )
 continue;
 
 break;
 default:
 if( !settings.IsTestEnabled( ERCE_LABEL_NOT_CONNECTED ) )
 continue;
 
 break;
 }
 
 for( SCH_TEXT* text : label_vec )
 {
 int allPins = pinCount;
 
 auto it = m_net_name_to_subgraphs_map.find( netName );
 
 if( it != m_net_name_to_subgraphs_map.end() )
 {
 for( const CONNECTION_SUBGRAPH* neighbor : it->second )
 {
 if( neighbor == aSubgraph )
 continue;
 
 if( neighbor->m_no_connect )
 has_nc = true;
 
 allPins += hasPins( neighbor );
 }
 }
 
 if( allPins == 1 && !has_nc )
 {
 reportError( text,
 type == SCH_GLOBAL_LABEL_T ? ERCE_GLOBLABEL : ERCE_LABEL_NOT_CONNECTED );
 ok = false;
 }
 
 if( allPins == 0 )
 {
 reportError( text,
 type == SCH_GLOBAL_LABEL_T ? ERCE_GLOBLABEL : ERCE_LABEL_NOT_CONNECTED );
 ok = false;
 }
 }
 }
 
 return ok;
}
 
 
int CONNECTION_GRAPH::ercCheckHierSheets()
{
 int errors = 0;
 
 ERC_SETTINGS& settings = m_schematic->ErcSettings();
 
 for( const SCH_SHEET_PATH& sheet : m_sheetList )
 {
 for( SCH_ITEM* item : sheet.LastScreen()->Items() )
 {
 if( item->Type() != SCH_SHEET_T )
 continue;
 
 SCH_SHEET* parentSheet = static_cast<SCH_SHEET*>( item );
 
 std::map<wxString, SCH_SHEET_PIN*> pins;
 std::map<wxString, SCH_HIERLABEL*> labels;
 
 for( SCH_SHEET_PIN* pin : parentSheet->GetPins() )
 {
 if( settings.IsTestEnabled( ERCE_HIERACHICAL_LABEL ) )
 pins[pin->GetText()] = pin;
 
 if( pin->IsDangling() && settings.IsTestEnabled( ERCE_PIN_NOT_CONNECTED ) )
 {
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_PIN_NOT_CONNECTED );
 ercItem->SetItems( pin );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, pin->GetPosition() );
 sheet.LastScreen()->Append( marker );
 
 errors++;
 }
 }
 
 if( settings.IsTestEnabled( ERCE_HIERACHICAL_LABEL ) )
 {
 std::set<wxString> matchedPins;
 
 for( SCH_ITEM* subItem : parentSheet->GetScreen()->Items() )
 {
 if( subItem->Type() == SCH_HIER_LABEL_T )
 {
 SCH_HIERLABEL* label = static_cast<SCH_HIERLABEL*>( subItem );
 
 if( !pins.count( label->GetText() ) )
 labels[label->GetText()] = label;
 else
 matchedPins.insert( label->GetText() );
 }
 }
 
 for( const wxString& matched : matchedPins )
 pins.erase( matched );
 
 for( const std::pair<const wxString, SCH_SHEET_PIN*>& unmatched : pins )
 {
 wxString msg = wxString::Format( _( "Sheet pin %s has no matching hierarchical "
 "label inside the sheet" ),
 UnescapeString( unmatched.first ) );
 
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_HIERACHICAL_LABEL );
 ercItem->SetItems( unmatched.second );
 ercItem->SetErrorMessage( msg );
 ercItem->SetSheetSpecificPath( sheet );
 ercItem->SetItemsSheetPaths( sheet );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, unmatched.second->GetPosition() );
 sheet.LastScreen()->Append( marker );
 
 errors++;
 }
 
 for( const std::pair<const wxString, SCH_HIERLABEL*>& unmatched : labels )
 {
 wxString msg = wxString::Format( _( "Hierarchical label %s has no matching "
 "sheet pin in the parent sheet" ),
 UnescapeString( unmatched.first ) );
 
 SCH_SHEET_PATH parentSheetPath = sheet;
 parentSheetPath.push_back( parentSheet );
 
 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_HIERACHICAL_LABEL );
 ercItem->SetItems( unmatched.second );
 ercItem->SetErrorMessage( msg );
 ercItem->SetSheetSpecificPath( parentSheetPath );
 ercItem->SetItemsSheetPaths( parentSheetPath );
 
 SCH_MARKER* marker = new SCH_MARKER( ercItem, unmatched.second->GetPosition() );
 parentSheet->GetScreen()->Append( marker );
 
 errors++;
 }
 }
 }
 }
 
 return errors;
}