Prevent single-element groups

Groups with fewer than two items serve no purpose. All
user-facing group creation paths now require at least two
items before creating a group. The Group menu action is
greyed out when fewer than two items are selected.

When items are removed from a group via RemoveFromGroup,
pruneExistingGroups, or the netlist updater, the group is
dissolved if it drops below two members. Importers are left
unchanged since they reflect external file structure.

common/tool/group_tool.cpp

@@ -22,6 +22,8 @@
  */
 #include "tool/group_tool.h"
 
+#include <set>
+
 #include <eda_draw_frame.h>
 #include <kiplatform/ui.h>
 #include <tool/actions.h>
@@ -61,7 +63,7 @@ public:
 private:
     void update() override
     {
-        bool canGroup = false;
+        int  selectionCount = 0;
         bool hasGroup = false;
         bool hasMember = false;
         bool onlyOneGroup = false;
@@ -71,7 +73,7 @@ private:
         {
             for( EDA_ITEM* item : m_selectionTool->GetSelection() )
             {
-                canGroup = true;
+                selectionCount++;
 
                 if( item->Type() == PCB_GROUP_T || item->Type() == SCH_GROUP_T )
                 {
@@ -92,7 +94,7 @@ private:
             }
         }
 
-        Enable( ACTIONS::group.GetUIId(),           canGroup );
+        Enable( ACTIONS::group.GetUIId(),           selectionCount >= 2 );
         Enable( ACTIONS::ungroup.GetUIId(),         hasGroup );
         Enable( ACTIONS::addToGroup.GetUIId(),      onlyOneGroup && hasUngroupedItems );
         Enable( ACTIONS::removeFromGroup.GetUIId(), hasMember );
@@ -253,6 +255,8 @@ int GROUP_TOOL::RemoveFromGroup( const TOOL_EVENT& aEvent )
     if( selection.Empty() )
         m_toolMgr->RunAction( ACTIONS::selectionCursor );
 
+    std::set<EDA_GROUP*> affectedGroups;
+
     for( EDA_ITEM* item : selection )
     {
         if( EDA_GROUP* group = item->GetParentGroup() )
@@ -260,6 +264,16 @@ int GROUP_TOOL::RemoveFromGroup( const TOOL_EVENT& aEvent )
             m_commit->Modify( group->AsEdaItem(), m_frame->GetScreen(), RECURSE_MODE::NO_RECURSE );
             m_commit->Modify( item, m_frame->GetScreen() );
             group->RemoveItem( item );
+            affectedGroups.insert( group );
+        }
+    }
+
+    for( EDA_GROUP* group : affectedGroups )
+    {
+        if( group->GetItems().size() < 2 )
+        {
+            group->RemoveAll();
+            m_commit->Remove( group->AsEdaItem(), m_frame->GetScreen() );
         }
     }
 

eeschema/sch_design_block_utils.cpp

@@ -394,7 +394,7 @@ bool SCH_EDIT_FRAME::SaveSelectionAsDesignBlock( const wxString& aLibraryName )
         newGroup->SetName( blk.GetLibId().GetUniStringLibItemName() );
         newGroup->SetDesignBlockLibId( blk.GetLibId() );
 
-        bool added = false;
+        int addedCount = 0;
 
         for( EDA_ITEM* edaItem : selection )
         {
@@ -414,10 +414,10 @@ bool SCH_EDIT_FRAME::SaveSelectionAsDesignBlock( const wxString& aLibraryName )
 
             commit.Modify( item, screen, RECURSE_MODE::NO_RECURSE );
             newGroup->AddItem( item );
-            added = true;
+            addedCount++;
         }
 
-        if( added )
+        if( addedCount >= 2 )
         {
             commit.Add( newGroup, screen );
             commit.Push( _( "Group Items" ) );
@@ -427,6 +427,7 @@ bool SCH_EDIT_FRAME::SaveSelectionAsDesignBlock( const wxString& aLibraryName )
         }
         else
         {
+            newGroup->RemoveAll();
             delete newGroup;
         }
     }
@@ -619,7 +620,7 @@ bool SCH_EDIT_FRAME::UpdateDesignBlockFromSelection( const LIB_ID& aLibId )
         newGroup->SetName( aLibId.GetUniStringLibItemName() );
         newGroup->SetDesignBlockLibId( aLibId );
 
-        bool added = false;
+        int addedCount = 0;
 
         for( EDA_ITEM* edaItem : selection )
         {
@@ -639,10 +640,10 @@ bool SCH_EDIT_FRAME::UpdateDesignBlockFromSelection( const LIB_ID& aLibId )
 
             commit.Modify( item, screen, RECURSE_MODE::NO_RECURSE );
             newGroup->AddItem( item );
-            added = true;
+            addedCount++;
         }
 
-        if( added )
+        if( addedCount >= 2 )
         {
             commit.Add( newGroup, screen );
             commit.Push( _( "Group Items" ) );
@@ -652,6 +653,7 @@ bool SCH_EDIT_FRAME::UpdateDesignBlockFromSelection( const LIB_ID& aLibId )
         }
         else
         {
+            newGroup->RemoveAll();
             delete newGroup;
         }
     }

eeschema/sch_edit_frame.cpp

@@ -813,7 +813,7 @@ void SCH_EDIT_FRAME::setupUIConditions()
     mgr->SetConditions( SCH_ACTIONS::rotateCCW,       ENABLE( hasElements ) );
     mgr->SetConditions( SCH_ACTIONS::mirrorH,         ENABLE( hasElements ) );
     mgr->SetConditions( SCH_ACTIONS::mirrorV,         ENABLE( hasElements ) );
-    mgr->SetConditions( ACTIONS::group,               ENABLE( SELECTION_CONDITIONS::NotEmpty ) );
+    mgr->SetConditions( ACTIONS::group,               ENABLE( SELECTION_CONDITIONS::MoreThan( 1 ) ) );
     mgr->SetConditions( ACTIONS::ungroup,             ENABLE( SELECTION_CONDITIONS::HasType( SCH_GROUP_T ) ) );
 
     mgr->SetConditions( SCH_ACTIONS::placeLinkedDesignBlock, ENABLE( groupWithDesignBlockLink ) );

eeschema/tools/sch_group_tool.cpp

@@ -150,7 +150,7 @@ int SCH_GROUP_TOOL::Group( const TOOL_EVENT& aEvent )
             selection.Remove( schItem );
     }
 
-    if( selection.Empty() )
+    if( selection.GetSize() < 2 )
         return 0;
 
     SCH_GROUP*  group = new SCH_GROUP;

pcbnew/footprint_edit_frame.cpp

@@ -1368,7 +1368,7 @@ void FOOTPRINT_EDIT_FRAME::setupUIConditions()
     mgr->SetConditions( PCB_ACTIONS::rotateCcw,          ENABLE( cond.HasItems() ) );
     mgr->SetConditions( PCB_ACTIONS::mirrorH,            ENABLE( cond.HasItems() ) );
     mgr->SetConditions( PCB_ACTIONS::mirrorV,            ENABLE( cond.HasItems() ) );
-    mgr->SetConditions( ACTIONS::group,                  ENABLE( SELECTION_CONDITIONS::NotEmpty ) );
+    mgr->SetConditions( ACTIONS::group,                  ENABLE( SELECTION_CONDITIONS::MoreThan( 1 ) ) );
     mgr->SetConditions( ACTIONS::ungroup,                ENABLE( SELECTION_CONDITIONS::HasType( PCB_GROUP_T ) ) );
 
     mgr->SetConditions( PCB_ACTIONS::padDisplayMode,     CHECK( !cond.PadFillDisplay() ) );

pcbnew/netlist_reader/board_netlist_updater.cpp

@@ -947,6 +947,12 @@ bool BOARD_NETLIST_UPDATER::updateFootprintGroup( FOOTPRINT* aPcbFootprint,
             changed = true;
             m_commit.Modify( existingGroup, nullptr, RECURSE_MODE::NO_RECURSE );
             existingGroup->RemoveItem( aPcbFootprint );
+
+            if( existingGroup->GetItems().size() < 2 )
+            {
+                existingGroup->RemoveAll();
+                m_commit.Remove( existingGroup );
+            }
         }
 
         m_reporter->Report( msg, RPT_SEVERITY_ACTION );

pcbnew/pcb_design_block_utils.cpp

@@ -423,7 +423,7 @@ bool PCB_EDIT_FRAME::SaveSelectionAsDesignBlock( const wxString& aLibraryName )
         newGroup->SetName( blk.GetLibId().GetUniStringLibItemName() );
         newGroup->SetDesignBlockLibId( blk.GetLibId() );
 
-        bool added = false;
+        int addedCount = 0;
 
         for( EDA_ITEM* edaItem : selection )
         {
@@ -443,10 +443,10 @@ bool PCB_EDIT_FRAME::SaveSelectionAsDesignBlock( const wxString& aLibraryName )
 
             commit.Modify( item, nullptr, RECURSE_MODE::NO_RECURSE );
             newGroup->AddItem( item );
-            added = true;
+            addedCount++;
         }
 
-        if( added )
+        if( addedCount >= 2 )
         {
             commit.Add( newGroup );
             commit.Push( _( "Group Items" ) );
@@ -456,6 +456,7 @@ bool PCB_EDIT_FRAME::SaveSelectionAsDesignBlock( const wxString& aLibraryName )
         }
         else
         {
+            newGroup->RemoveAll();
             delete newGroup;
         }
     }
@@ -560,7 +561,7 @@ bool PCB_EDIT_FRAME::UpdateDesignBlockFromSelection( const LIB_ID& aLibId )
         newGroup->SetName( aLibId.GetUniStringLibItemName() );
         newGroup->SetDesignBlockLibId( aLibId );
 
-        bool added = false;
+        int addedCount = 0;
 
         for( EDA_ITEM* edaItem : selection )
         {
@@ -580,10 +581,10 @@ bool PCB_EDIT_FRAME::UpdateDesignBlockFromSelection( const LIB_ID& aLibId )
 
             commit.Modify( item, nullptr, RECURSE_MODE::NO_RECURSE );
             newGroup->AddItem( item );
-            added = true;
+            addedCount++;
         }
 
-        if( added )
+        if( addedCount >= 2 )
         {
             commit.Add( newGroup );
             commit.Push( _( "Group Items" ) );
@@ -593,6 +594,7 @@ bool PCB_EDIT_FRAME::UpdateDesignBlockFromSelection( const LIB_ID& aLibId )
         }
         else
         {
+            newGroup->RemoveAll();
             delete newGroup;
         }
     }

pcbnew/pcb_edit_frame.cpp

@@ -1014,7 +1014,7 @@ void PCB_EDIT_FRAME::setupUIConditions()
 
     static const std::vector<KICAD_T> groupTypes = { PCB_GROUP_T, PCB_GENERATOR_T };
 
-    mgr->SetConditions( ACTIONS::group,        ENABLE( SELECTION_CONDITIONS::NotEmpty ) );
+    mgr->SetConditions( ACTIONS::group,        ENABLE( SELECTION_CONDITIONS::MoreThan( 1 ) ) );
     mgr->SetConditions( ACTIONS::ungroup,      ENABLE( SELECTION_CONDITIONS::HasTypes( groupTypes ) ) );
     mgr->SetConditions( PCB_ACTIONS::lock,     ENABLE( PCB_SELECTION_CONDITIONS::HasUnlockedItems ) );
     mgr->SetConditions( PCB_ACTIONS::unlock,   ENABLE( PCB_SELECTION_CONDITIONS::HasLockedItems ) );

pcbnew/tools/drawing_tool.cpp

@@ -2076,11 +2076,20 @@ int DRAWING_TOOL::PlaceImportedGraphics( const TOOL_EVENT& aEvent )
 
     if( dlg.ShouldGroupItems() )
     {
-        group = new PCB_GROUP( m_frame->GetModel() );
+        size_t boardItemCount = std::count_if( list.begin(), list.end(),
+                                               []( const std::unique_ptr<EDA_ITEM>& ptr )
+                                               {
+                                                   return ptr->IsBOARD_ITEM();
+                                               } );
 
-        newItems.push_back( group );
-        selectedItems.push_back( group );
-        preview.Add( group );
+        if( boardItemCount >= 2 )
+        {
+            group = new PCB_GROUP( m_frame->GetModel() );
+
+            newItems.push_back( group );
+            selectedItems.push_back( group );
+            preview.Add( group );
+        }
     }
 
     if( dlg.ShouldFixDiscontinuities() )

pcbnew/tools/multichannel_tool.cpp

@@ -885,6 +885,9 @@ int MULTICHANNEL_TOOL::RepeatLayout( const TOOL_EVENT& aEvent, ZONE* aRefZone )
     {
         for( const auto& [targetArea, compatData] : m_areas.m_compatMap )
         {
+            if( compatData.m_groupableItems.size() < 2 )
+                continue;
+
             pruneExistingGroups( commit, compatData.m_affectedItems );
 
             PCB_GROUP* group = new PCB_GROUP( board() );
@@ -1533,7 +1536,7 @@ bool MULTICHANNEL_TOOL::pruneExistingGroups( COMMIT& aCommit,
             for( EDA_ITEM* item : pruneList )
                 group->RemoveItem( item );
 
-            if( group->GetItems().empty() )
+            if( group->GetItems().size() < 2 )
                 aCommit.Remove( group );
         }
     }
@@ -1712,6 +1715,10 @@ int MULTICHANNEL_TOOL::AutogenerateRuleAreas( const TOOL_EVENT& aEvent )
             if( ra.m_existsAlready && !m_areas.m_replaceExisting )
                 continue;
 
+            // A group needs at least 2 items (zone + at least 1 component)
+            if( ra.m_components.empty() )
+                continue;
+
             std::unordered_set<BOARD_ITEM*> toPrune;
 
             std::copy( ra.m_components.begin(), ra.m_components.end(), std::inserter( toPrune, toPrune.begin() ) );

pcbnew/tools/pcb_control.cpp

@@ -2064,48 +2064,63 @@ int PCB_CONTROL::AppendBoard( PCB_IO& pi, const wxString& fileName, DESIGN_BLOCK
     {
         if( placeAsGroup )
         {
-            PCB_GROUP* group = new PCB_GROUP( brd );
-
-            if( aDesignBlock )
-            {
-                group->SetName( aDesignBlock->GetLibId().GetLibItemName() );
-                group->SetDesignBlockLibId( aDesignBlock->GetLibId() );
-            }
-            else
-            {
-                group->SetName( wxFileName( fileName ).GetName() );
-            }
-
-            // Get the selection tool selection
             PCB_SELECTION_TOOL* selTool = m_toolMgr->GetTool<PCB_SELECTION_TOOL>();
             PCB_SELECTION       selection = selTool->GetSelection();
 
-            for( EDA_ITEM* eda_item : selection )
-            {
-                if( eda_item->IsBOARD_ITEM() )
-                {
-                    if( static_cast<BOARD_ITEM*>( eda_item )->IsLocked() )
-                        group->SetLocked( true );
-                }
-            }
-
-            commit->Add( group );
+            // Count items that would be added to the group
+            int groupableCount = 0;
 
             for( EDA_ITEM* eda_item : selection )
             {
-                if( eda_item->IsBOARD_ITEM() && !static_cast<BOARD_ITEM*>( eda_item )->GetParentFootprint() )
+                if( eda_item->IsBOARD_ITEM()
+                    && !static_cast<BOARD_ITEM*>( eda_item )->GetParentFootprint() )
                 {
-                    commit->Modify( eda_item );
-                    group->AddItem( eda_item );
+                    groupableCount++;
                 }
             }
 
-            selTool->ClearSelection();
-            selTool->select( group );
+            if( groupableCount >= 2 )
+            {
+                PCB_GROUP* group = new PCB_GROUP( brd );
 
-            m_toolMgr->PostEvent( EVENTS::SelectedItemsModified );
-            m_frame->OnModify();
-            m_frame->Refresh();
+                if( aDesignBlock )
+                {
+                    group->SetName( aDesignBlock->GetLibId().GetLibItemName() );
+                    group->SetDesignBlockLibId( aDesignBlock->GetLibId() );
+                }
+                else
+                {
+                    group->SetName( wxFileName( fileName ).GetName() );
+                }
+
+                for( EDA_ITEM* eda_item : selection )
+                {
+                    if( eda_item->IsBOARD_ITEM() )
+                    {
+                        if( static_cast<BOARD_ITEM*>( eda_item )->IsLocked() )
+                            group->SetLocked( true );
+                    }
+                }
+
+                commit->Add( group );
+
+                for( EDA_ITEM* eda_item : selection )
+                {
+                    if( eda_item->IsBOARD_ITEM()
+                        && !static_cast<BOARD_ITEM*>( eda_item )->GetParentFootprint() )
+                    {
+                        commit->Modify( eda_item );
+                        group->AddItem( eda_item );
+                    }
+                }
+
+                selTool->ClearSelection();
+                selTool->select( group );
+
+                m_toolMgr->PostEvent( EVENTS::SelectedItemsModified );
+                m_frame->OnModify();
+                m_frame->Refresh();
+            }
         }
 
         // If we were provided a commit, let the caller control when to push it

pcbnew/tools/pcb_group_tool.cpp

@@ -176,7 +176,7 @@ int PCB_GROUP_TOOL::Group( const TOOL_EVENT& aEvent )
                 } );
     }
 
-    if( selection.Empty() )
+    if( selection.GetSize() < 2 )
         return 0;
 
     BOARD*       board = getModel<BOARD>();