Track alt pin changes

Make sure that we are following the lib changes when updating

Fixes https://gitlab.com/kicad/code/kicad/issues/21202

eeschema/sch_symbol.cpp

@@ -288,6 +288,7 @@ wxString SCH_SYMBOL::GetDatasheet() const
 void SCH_SYMBOL::UpdatePins()
 {
     std::map<wxString, wxString>            altPinMap;
+    std::map<wxString, SCH_PIN::ALT>        altPinDefs;
     std::map<wxString, std::set<SCH_PIN*>>  pinUuidMap;
     std::set<SCH_PIN*>                      unassignedSchPins;
     std::set<SCH_PIN*>                      unassignedLibPins;
@@ -299,8 +300,15 @@ void SCH_SYMBOL::UpdatePins()
         unassignedSchPins.insert( pin.get() );
 
         if( !pin->GetAlt().IsEmpty() )
+        {
             altPinMap[ pin->GetNumber() ] = pin->GetAlt();
 
+            auto altDefIt = pin->GetAlternates().find( pin->GetAlt() );
+
+            if( altDefIt != pin->GetAlternates().end() )
+                altPinDefs[ pin->GetNumber() ] = altDefIt->second;
+        }
+
         pin->SetLibPin( nullptr );
     }
 
@@ -329,6 +337,7 @@ void SCH_SYMBOL::UpdatePins()
         auto it = ii->second.begin();
         pin = *it;
         ii->second.erase( it );
+        pin->GetAlternates() = libPin->GetAlternates();
         pin->SetLibPin( libPin );
         pin->SetPosition( libPin->GetPosition() );
 
@@ -337,7 +346,28 @@ void SCH_SYMBOL::UpdatePins()
         auto iii = altPinMap.find( libPin->GetNumber() );
 
         if( iii != altPinMap.end() )
-            pin->SetAlt( iii->second );
+        {
+            wxString altName = iii->second;
+
+            if( pin->GetAlternates().find( altName ) == pin->GetAlternates().end() )
+            {
+                auto defIt = altPinDefs.find( libPin->GetNumber() );
+
+                if( defIt != altPinDefs.end() )
+                {
+                    for( const auto& [ name, alt ] : pin->GetAlternates() )
+                    {
+                        if( alt.m_Shape == defIt->second.m_Shape && alt.m_Type == defIt->second.m_Type )
+                        {
+                            altName = name;
+                            break;
+                        }
+                    }
+                }
+            }
+
+            pin->SetAlt( altName );
+        }
 
         m_pinMap[ libPin ] = pin;
     }
@@ -361,6 +391,7 @@ void SCH_SYMBOL::UpdatePins()
         }
 
         m_pinMap[ libPin ] = pin;
+        pin->GetAlternates() = libPin->GetAlternates();
         pin->SetLibPin( libPin );
         pin->SetPosition( libPin->GetPosition() );
         pin->SetNumber( libPin->GetNumber() );
@@ -368,7 +399,28 @@ void SCH_SYMBOL::UpdatePins()
         auto iii = altPinMap.find( libPin->GetNumber() );
 
         if( iii != altPinMap.end() )
-            pin->SetAlt( iii->second );
+        {
+            wxString altName = iii->second;
+
+            if( pin->GetAlternates().find( altName ) == pin->GetAlternates().end() )
+            {
+                auto defIt = altPinDefs.find( libPin->GetNumber() );
+
+                if( defIt != altPinDefs.end() )
+                {
+                    for( const auto& [ name, alt ] : pin->GetAlternates() )
+                    {
+                        if( alt.m_Shape == defIt->second.m_Shape && alt.m_Type == defIt->second.m_Type )
+                        {
+                            altName = name;
+                            break;
+                        }
+                    }
+                }
+            }
+
+            pin->SetAlt( altName );
+        }
     }
 
     // If we have any pins left in the symbol that were not found in the library, remove them.

qa/tests/eeschema/test_sch_pin.cpp

@@ -189,4 +189,30 @@ BOOST_AUTO_TEST_CASE( PinNumberingPower )
     BOOST_CHECK_EQUAL( pwr_name, "voltage_value" );
 }
 
+BOOST_AUTO_TEST_CASE( AlternatePinRenameUpdates )
+{
+    SCH_PIN::ALT alt;
+    alt.m_Name = wxS( "ALT1" );
+    alt.m_Shape = GRAPHIC_PINSHAPE::INVERTED;
+    alt.m_Type = ELECTRICAL_PINTYPE::PT_INPUT;
+    m_lib_pin->GetAlternates()[ wxS( "ALT1" ) ] = alt;
+
+    m_parent_symbol->UpdatePins();
+    m_sch_pin = m_parent_symbol->GetPins()[0];
+    m_sch_pin->SetAlt( wxS( "ALT1" ) );
+
+    SCH_PIN::ALT altNew = alt;
+    m_lib_pin->GetAlternates().erase( wxS( "ALT1" ) );
+    altNew.m_Name = wxS( "ALT1_NEW" );
+    m_lib_pin->GetAlternates()[ wxS( "ALT1_NEW" ) ] = altNew;
+
+    m_parent_symbol->SetLibSymbol( m_parent_part->Flatten().release() );
+    m_parent_symbol->UpdatePins();
+
+    SCH_PIN* updatedPin = m_parent_symbol->GetPins()[0];
+
+    BOOST_CHECK_EQUAL( updatedPin->GetAlt(), "ALT1_NEW" );
+    BOOST_CHECK( updatedPin->GetAlternates().count( wxS( "ALT1" ) ) == 0 );
+}
+
 BOOST_AUTO_TEST_SUITE_END()