Fix diff pair router checking of min clearance

Fixes https://gitlab.com/kicad/code/kicad/-/issues/13720

pcbnew/router/pns_kicad_iface.cpp

@@ -596,6 +596,7 @@ bool PNS_KICAD_IFACE_BASE::ImportSizes( PNS::SIZES_SETTINGS& aSizes, PNS::ITEM*
     if( aStartItem && m_startLayer < 0 )
         m_startLayer = aStartItem->Layer();
 
+    aSizes.SetClearance( bds.m_MinClearance );
     aSizes.SetMinClearance( bds.m_MinClearance );
     aSizes.SetClearanceSource( _( "board minimum clearance" ) );
 
@@ -604,7 +605,7 @@ bool PNS_KICAD_IFACE_BASE::ImportSizes( PNS::SIZES_SETTINGS& aSizes, PNS::ITEM*
     {
         if( constraint.m_Value.Min() > bds.m_MinClearance )
         {
-            aSizes.SetMinClearance( constraint.m_Value.Min() );
+            aSizes.SetClearance( constraint.m_Value.Min() );
             aSizes.SetClearanceSource( constraint.m_RuleName );
         }
     }

pcbnew/router/pns_sizes_settings.h

@@ -38,6 +38,7 @@ class SIZES_SETTINGS
 {
 public:
     SIZES_SETTINGS() :
+            m_clearance( 0 ),
             m_minClearance( 0 ),
             m_trackWidth( 155000 ),
             m_trackWidthIsExplicit( true ),
@@ -56,6 +57,12 @@ public:
     void ClearLayerPairs();
     void AddLayerPair( int aL1, int aL2 );
 
+    // The working clearance, from the current net to anything else (without knowing the net of the
+    // other object).  Specific clearance to another object may be resolved differently.
+    int Clearance() const { return m_clearance; }
+    void SetClearance( int aClearance ) { m_clearance = aClearance; }
+
+    // The absolute minimum clearance from the board
     int MinClearance() const { return m_minClearance; }
     void SetMinClearance( int aClearance ) { m_minClearance = aClearance; }
 
@@ -116,6 +123,7 @@ public:
     void SetDiffPairGapSource( const wxString& aSource ) { m_diffPairGapSource = aSource; }
 
 private:
+    int     m_clearance;
     int     m_minClearance;
     int     m_trackWidth;
     bool    m_trackWidthIsExplicit;

pcbnew/router/router_tool.cpp

@@ -2546,7 +2546,7 @@ void ROUTER_TOOL::UpdateMessagePanel()
                                                   sizes.GetDiffPairWidthSource() ) );
 
             items.emplace_back( wxString::Format( _( "Min Clearance: %s" ),
-                                                  FORMAT_VALUE( sizes.MinClearance() ) ),
+                                                  FORMAT_VALUE( sizes.Clearance() ) ),
                                 wxString::Format( _( "(from %s)" ),
                                                   sizes.GetClearanceSource() ) );
 
@@ -2563,7 +2563,7 @@ void ROUTER_TOOL::UpdateMessagePanel()
                                                   sizes.GetWidthSource() ) );
 
             items.emplace_back( wxString::Format( _( "Min Clearance: %s" ),
-                                                  FORMAT_VALUE( sizes.MinClearance() ) ),
+                                                  FORMAT_VALUE( sizes.Clearance() ) ),
                                 wxString::Format( _( "(from %s)" ),
                                                   sizes.GetClearanceSource() ) );
         }