Introduce new KI_FALLTHROUGH macro

Annotate purposeful fallthroughs in switch statements with the
KI_FALLTHROUGH macro.

3d-viewer/3d_rendering/3d_render_raytracing/accelerators/cbvh_pbrt.cpp

@@ -68,6 +68,8 @@
 
 #include "cbvh_pbrt.h"
 #include "../../../3d_fastmath.h"
+#include <macros.h>
+
 #include <boost/range/algorithm/nth_element.hpp>
 #include <boost/range/algorithm/partition.hpp>
 #include <cstdlib>
@@ -560,6 +562,7 @@ BVHBuildNode *CBVH_PBRT::recursiveBuild ( std::vector<BVHPrimitiveInfo> &primiti
 
             // Intentionally fall through to SPLITMETHOD::EQUAL_COUNTS since prims
             // with large overlapping bounding boxes may fail to partition
+            KI_FALLTHROUGH;
 
             case SPLITMETHOD::EQUALCOUNTS:
             {

common/base_units.cpp

@@ -147,10 +147,12 @@ wxString MessageTextFromValue( EDA_UNITS aUnits, double aValue, bool aUseMils, E
     case EDA_DATA_TYPE::VOLUME:
         value = To_User_Unit( aUnits, value, aUseMils );
         // Fall through to continue computation
+        KI_FALLTHROUGH;
 
     case EDA_DATA_TYPE::AREA:
         value = To_User_Unit( aUnits, value, aUseMils );
         // Fall through to continue computation
+        KI_FALLTHROUGH;
 
     case EDA_DATA_TYPE::DISTANCE:
         value = To_User_Unit( aUnits, value, aUseMils );

common/common.cpp

@@ -28,6 +28,7 @@
 #include <project.h>
 #include <common.h>
 #include <reporter.h>
+#include <macros.h>
 #include <mutex>
 #include <wx/process.h>
 #include <wx/config.h>
@@ -548,7 +549,7 @@ wxString KIwxExpandEnvVars( const wxString& str, const PROJECT* aProject )
 
                 break;
             }
-            // else fall through
+            KI_FALLTHROUGH;
 
         default:
             strResult += str_n;

common/draw_panel_gal.cpp

@@ -27,6 +27,7 @@
 #include <confirm.h>
 #include <eda_draw_frame.h>
 #include <kiface_i.h>
+#include <macros.h>
 #include <settings/app_settings.h>
 
 #include <class_draw_panel_gal.h>
@@ -386,6 +387,7 @@ bool EDA_DRAW_PANEL_GAL::SwitchBackend( GAL_TYPE aGalType )
 
         default:
             wxASSERT( false );
+            KI_FALLTHROUGH;
             // warn about unhandled GAL canvas type, but continue with the fallback option
 
         case GAL_TYPE_NONE:

common/page_layout/page_layout_reader.cpp

@@ -177,6 +177,7 @@ wxString convertLegacyVariableRefs( const wxString& aTextbase )
                 case '8': msg += wxT( "${COMMENT8}" );  break;
                 case '9': msg += wxT( "${COMMENT9}" );  break;
                 }
+                break;
 
             default:
                 break;

common/plotters/GERBER_plotter.cpp

@@ -819,7 +819,8 @@ void GERBER_PLOTTER::FlashPadRect( const wxPoint& pos, const wxSize& aSize,
     case 900:
     case 2700:        // rotation of 90 degrees or 270 swaps sizes
         std::swap( size.x, size.y );
-        // Intentionally fall through
+        KI_FALLTHROUGH;
+
     case 0:
     case 1800:
         if( trace_mode == SKETCH )

common/plotters/PS_plotter.cpp

@@ -324,8 +324,8 @@ void PSLIKE_PLOTTER::fputsPostscriptString(FILE *fout, const wxString& txt)
             case ')':
             case '\\':
                 putc( '\\', fout );
+                KI_FALLTHROUGH;
 
-                // FALLTHRU
             default:
                 putc( ch, fout );
                 break;

common/widgets/lib_tree.cpp

@@ -23,6 +23,7 @@
  */
 
 #include "lib_tree.h"
+#include <macros.h>
 #include <wxdataviewctrl_helpers.h>
 #include <wx/artprov.h>
 #include <wx/sizer.h>
@@ -365,6 +366,7 @@ void LIB_TREE::onQueryCharHook( wxKeyEvent& aKeyStroke )
             break;
         }
         // Intentionally fall through, so the selected component will be treated as the selected one
+        KI_FALLTHROUGH;
 
     default:
         aKeyStroke.Skip(); // Any other key: pass on to search box directly.

eeschema/connection_graph.cpp

@@ -28,6 +28,7 @@
 
 #include <common.h>
 #include <erc.h>
+#include <macros.h>
 #include <sch_bus_entry.h>
 #include <sch_component.h>
 #include <sch_edit_frame.h>
@@ -207,7 +208,10 @@ std::vector<SCH_ITEM*> CONNECTION_SUBGRAPH::GetBusLabels() const
             // Only consider bus vectors
             if( label_conn->Type() == CONNECTION_TYPE::BUS )
                 labels.push_back( item );
+
+            break;
         }
+
         default: break;
         }
     }

eeschema/netlist_object_list.cpp

@@ -25,6 +25,7 @@
 
 #include <netlist_object.h>
 #include <class_library.h>
+#include <macros.h>
 #include <sch_junction.h>
 #include <sch_component.h>
 #include <sch_line.h>
@@ -115,6 +116,7 @@ bool NETLIST_OBJECT_LIST::BuildNetListInfo( SCH_SHEET_LIST& aSheets )
                 break;
 
             // Intentionally fall through if there is no net assigned
+            KI_FALLTHROUGH;
 
         case NETLIST_ITEM::SEGMENT:
             // Test connections point to point type without bus.
@@ -165,6 +167,7 @@ bool NETLIST_OBJECT_LIST::BuildNetListInfo( SCH_SHEET_LIST& aSheets )
                 break;
 
             // Intentionally fall through if there is no bus assigned
+            KI_FALLTHROUGH;
 
         case NETLIST_ITEM::BUS:
             // Control type connections point to point mode bus

eeschema/sch_eagle_plugin.cpp

@@ -44,6 +44,7 @@
 #include <lib_polyline.h>
 #include <lib_rectangle.h>
 #include <lib_text.h>
+#include <macros.h>
 #include <project.h>
 #include <sch_bus_entry.h>
 #include <sch_component.h>
@@ -229,6 +230,7 @@ static COMPONENT_ORIENTATION_T kiCadComponentRotation( float eagleDegrees )
     {
     default:
         wxASSERT_MSG( false, wxString::Format( "Unhandled orientation (%d degrees)", roti ) );
+        KI_FALLTHROUGH;
 
     case 0:
         return CMP_ORIENT_0;
@@ -1701,8 +1703,8 @@ LIB_PIN* SCH_EAGLE_PLUGIN::loadPin(
     {
     default:
         wxASSERT_MSG( false, wxString::Format( "Unhandled orientation (%d degrees)", roti ) );
+        KI_FALLTHROUGH;
 
-    // fall through
     case 0:
         pin->SetOrientation( 'R' );
         break;

eeschema/sch_screen.cpp

@@ -836,6 +836,8 @@ SCH_TEXT* SCH_SCREEN::GetLabel( const wxPoint& aPosition, int aAccuracy )
             if( item->HitTest( aPosition, aAccuracy ) )
                 return (SCH_TEXT*) item;
 
+            break;
+
         default:
             ;
         }

eeschema/sch_text.cpp

@@ -40,6 +40,7 @@
 #include <msgpanel.h>
 #include <gal/stroke_font.h>
 #include <bitmaps.h>
+#include <macros.h>
 #include <math/util.h>      // for KiROUND
 #include <kiway.h>
 #include <sch_text.h>
@@ -357,7 +358,7 @@ bool SCH_TEXT::UpdateDanglingState( std::vector<DANGLING_END_ITEM>& aItemList,
 
         case BUS_START_END:
             m_connectionType = CONNECTION_TYPE::BUS;
-            // fall through
+            KI_FALLTHROUGH;
 
         case WIRE_START_END:
         {

gerbview/am_param.cpp

@@ -29,6 +29,7 @@
 
 #include <am_param.h>
 #include <am_primitive.h>
+#include <macros.h>
 
 extern int    ReadInt( char*& text, bool aSkipSeparator = true );
 extern double ReadDouble( char*& text, bool aSkipSeparator = true );
@@ -184,7 +185,9 @@ bool AM_PARAM::ReadParam( char*& aText  )
 
             if( !found )    // happens when a string starts by ',' before any param
                 break;      // just skip this separator
-            // fall through
+
+            KI_FALLTHROUGH;
+
         case '\n':
         case '\r':
         case 0:     // EOL

gerbview/rs274x.cpp

@@ -234,7 +234,7 @@ bool GERBER_FILE_IMAGE::ExecuteRS274XCommand( int aCommand, char* aBuff,
                 msg.Printf( _("GERBER file \"%s\" may not display as intended." ),
                         m_FileName.ToAscii() );
                 AddMessageToList( msg );
-                // Fallthrough
+                KI_FALLTHROUGH;
 
             case 'L':       // No Leading 0
                 m_NoTrailingZeros = false;

include/macros.h

@@ -1,8 +1,9 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
+ * Copyright (C) 2020 Ian McInerney <ian.s.mcinerney@ieee.org>
  * Copyright (C) 2007-2014 Jean-Pierre Charras, jp.charras at wanadoo.fr
- * Copyright (C) 1992-2015 KiCad Developers, see CHANGELOG.TXT for contributors.
+ * Copyright (C) 1992-2020 KiCad Developers, see CHANGELOG.TXT for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -37,6 +38,57 @@
 #include <set>
 #include <memory>       // std::shared_ptr
 
+#if defined( __has_attribute )
+    #define KI_HAS_ATTRIBUTE( x ) __has_attribute( x )
+#else
+    #define KI_HAS_ATTRIBUTE( x ) 0
+#endif
+
+// Based on the declaration inside the LLVM source code
+#if defined( __cplusplus ) && defined( __has_cpp_attribute )
+    #define KI_HAS_CPP_ATTRIBUTE( x ) __has_cpp_attribute( x )
+#else
+    #define KI_HAS_CPP_ATTRIBUTE( x ) 0
+#endif
+
+/**
+ * The KI_FALLTHROUGH macro is to be used when switch statement cases should purposely
+ * fallthrough from one to the next. It must be followed by a ";".
+ *
+ * Sample code:
+ *     switch( a )
+ *     {
+ *     case 1:
+ *         // Some code
+ *         KI_FALLTHROUGH;
+ *
+ *     case 2:
+ *         // More code
+ *         break;
+ *     }
+ */
+#if __cplusplus >= 201703L
+    // C++ 17 includes this macro on all compilers
+    #define KI_FALLTHROUGH [[fallthrough]]
+
+#elif KI_HAS_CPP_ATTRIBUTE( clang::fallthrough )
+    // Clang provides this attribute to silence the "-Wimplicit-fallthrough" warning
+    #define KI_FALLTHROUGH [[clang::fallthrough]]
+
+#elif KI_HAS_CPP_ATTRIBUTE( gnu::fallthrough )
+    // GNU-specific C++ attribute to sliencing the warning
+    #define KI_FALLTHROUGH [[gnu::fallthrough]]
+
+#elif defined( __GNUC__ ) && __GNUC__ >= 7
+    // GCC 7+ includes the "-Wimplicit-fallthrough" warning, and this attribute to silence it
+    #define KI_FALLTHROUGH __attribute__ ((fallthrough))
+
+#else
+    // In every other case, don't do anything
+    #define KI_FALLTHROUGH ( ( void ) 0 )
+
+#endif
+
 /**
  * Macro TO_UTF8
  * converts a wxString to a UTF8 encoded C string for all wxWidgets build modes.

pagelayout_editor/dialogs/dialog_new_dataitem.cpp

@@ -125,7 +125,8 @@ void DIALOG_NEW_DATAITEM::initDlg()
     case WS_DATA_ITEM::WS_BITMAP:
     case WS_DATA_ITEM::WS_POLYPOLYGON:
         m_textCtrlText->Enable( false );
-        // fall through
+        KI_FALLTHROUGH;
+
     case WS_DATA_ITEM::WS_TEXT:
         m_textCtrlEndX->Enable( false );
         m_textCtrlEndY->Enable( false );

pcbnew/class_edge_mod.cpp

@@ -172,7 +172,8 @@ void EDGE_MODULE::Flip( const wxPoint& aCentre, bool aFlipLeftRight )
     {
     case S_ARC:
         SetAngle( -GetAngle() );
-        //Fall through
+        KI_FALLTHROUGH;
+
     default:
     case S_SEGMENT:
     case S_CURVE:
@@ -236,7 +237,8 @@ void EDGE_MODULE::Mirror( wxPoint aCentre, bool aMirrorAroundXAxis )
     {
     case S_ARC:
         SetAngle( -GetAngle() );
-        //Fall through
+        KI_FALLTHROUGH;
+
     default:
     case S_CURVE:
     case S_SEGMENT:

pcbnew/class_module.cpp

@@ -298,8 +298,7 @@ void MODULE::Add( BOARD_ITEM* aBoardItem, ADD_MODE aMode )
     case PCB_MODULE_TEXT_T:
         // Only user text can be added this way.
         assert( static_cast<TEXTE_MODULE*>( aBoardItem )->GetType() == TEXTE_MODULE::TEXT_is_DIVERS );
-
-        // no break
+        KI_FALLTHROUGH;
 
     case PCB_MODULE_EDGE_T:
         if( aMode == ADD_MODE::APPEND )
@@ -347,8 +346,7 @@ void MODULE::Remove( BOARD_ITEM* aBoardItem )
         wxCHECK_RET(
                 static_cast<TEXTE_MODULE*>( aBoardItem )->GetType() == TEXTE_MODULE::TEXT_is_DIVERS,
                 "Please report this bug: Invalid remove operation on required text" );
-
-        // no break
+        KI_FALLTHROUGH;
 
     case PCB_MODULE_EDGE_T:
         for( auto it = m_drawings.begin(); it != m_drawings.end(); ++it )
@@ -828,7 +826,8 @@ SEARCH_RESULT MODULE::Visit( INSPECTOR inspector, void* testData, const KICAD_T
             if( result == SEARCH_RESULT::QUIT )
                 break;
 
-        // Intentionally fall through since m_Drawings can hold TYPETEXTMODULE also
+            // Intentionally fall through since m_Drawings can hold TYPETEXTMODULE also
+            KI_FALLTHROUGH;
 
         case PCB_MODULE_EDGE_T:
             result = IterateForward<BOARD_ITEM*>( m_drawings, inspector, testData, p );
@@ -949,7 +948,8 @@ void MODULE::ViewGetLayers( int aLayers[], int& aCount ) const
 
     default:
         wxASSERT_MSG( false, "Illegal layer" );    // do you really have modules placed on other layers?
-        // pass through
+        KI_FALLTHROUGH;
+
     case F_Cu:
         aLayers[1] = LAYER_MOD_FR;
         break;

pcbnew/collectors.cpp

@@ -32,6 +32,7 @@
 #include <class_marker_pcb.h>
 #include <class_zone.h>
 #include <class_drawsegment.h>
+#include <macros.h>
 #include <math/util.h>      // for KiROUND
 
 
@@ -277,7 +278,10 @@ SEARCH_RESULT GENERAL_COLLECTOR::Inspect( EDA_ITEM* testItem, void* testData )
 
     case PCB_MODULE_ZONE_AREA_T:
         module = static_cast<MODULE*>( item->GetParent() );
-        // Fall through
+
+        // Fallthrough to get the zone as well
+        KI_FALLTHROUGH;
+
     case PCB_ZONE_AREA_T:
         zone = static_cast<ZONE_CONTAINER*>( item );
         break;

pcbnew/cross-probing.cpp

@@ -381,6 +381,8 @@ void PCB_EDIT_FRAME::KiwayMailIn( KIWAY_EXPRESS& mail )
 
         if( importFormat >= 0 )
             importFile( path, importFormat );
+
+        break;
     }
 
     // many many others.

pcbnew/dialogs/dialog_graphic_item_properties.cpp

@@ -325,7 +325,7 @@ bool DIALOG_GRAPHIC_ITEM_PROPERTIES::Validate()
         // Check angle of arc.
         if( m_angle.GetValue() == 0 )
             error_msgs.Add( _( "The arc angle cannot be zero." ) );
-        // Fall through.
+        KI_FALLTHROUGH;
 
     case S_CIRCLE:
         // Check radius.

pcbnew/dialogs/dialog_pad_properties.cpp

@@ -34,6 +34,7 @@
 #include <dialog_pad_properties.h>
 #include <gal/graphics_abstraction_layer.h>
 #include <html_messagebox.h>
+#include <macros.h>
 #include <pcb_base_frame.h>
 #include <pcb_painter.h>
 #include <pcbnew.h>
@@ -1110,7 +1111,8 @@ bool DIALOG_PAD_PROPERTIES::padValuesOK()
         if( padlayers_mask[B_Paste] || padlayers_mask[F_Paste] )
             error_msgs.Add( _( "Error: Connector pads are not on the solder paste layer\n"
                                "Use SMD pads instead" ) );
-        // Intentionally fall through
+        KI_FALLTHROUGH;
+
     case PAD_ATTRIB_SMD:       // SMD and Connector pads (One external copper layer only)
         {
         LSET innerlayers_mask = padlayers_mask & LSET::InternalCuMask();

pcbnew/dialogs/dialog_plot.cpp

@@ -41,6 +41,7 @@
 #include <tool/tool_manager.h>
 #include <tools/zone_filler_tool.h>
 #include <math/util.h>      // for KiROUND
+#include <macros.h>
 
 
 DIALOG_PLOT::DIALOG_PLOT( PCB_EDIT_FRAME* aParent ) :
@@ -402,6 +403,8 @@ void DIALOG_PLOT::SetPlotFormat( wxCommandEvent& event )
     {
     case PLOT_FORMAT::SVG:
         m_PlotOptionsSizer->Show( m_svgOptionsSizer );
+        KI_FALLTHROUGH;
+
     case PLOT_FORMAT::PDF:
         m_drillShapeOpt->Enable( true );
         m_plotModeOpt->Enable( false );

pcbnew/dialogs/dialog_push_pad_properties.cpp

@@ -25,6 +25,7 @@
 #include <dialog_push_pad_properties.h>
 
 #include <class_pad.h>
+#include <macros.h>
 #include <pcb_edit_frame.h>
 
 
@@ -72,8 +73,7 @@ void DIALOG_PUSH_PAD_PROPERTIES::PadPropertiesAccept( wxCommandEvent& event )
     {
     case wxID_APPLY:
         returncode = 1;
-
-    // Fall through
+        KI_FALLTHROUGH;
 
     case wxID_OK:
         m_Pad_Shape_Filter  = m_Pad_Shape_Filter_CB->GetValue();