Handle legacy libraries with escaped symbol names.

Fixes https://gitlab.com/kicad/code/kicad/issues/14057

common/string_utils.cpp

@@ -159,9 +159,12 @@ wxString EscapeString( const wxString& aSource, ESCAPE_CONTEXT aContext )
             else
                 converted += c;
         }
-        else if( aContext == CTX_LIBID )
+        else if( aContext == CTX_LIBID || aContext == CTX_LEGACY_LIBID )
         {
-            if( c == '\\' )
+            // We no longer escape '/' in LIB_IDs, but we used to
+            if( c == '/' && aContext == CTX_LEGACY_LIBID )
+                converted += wxT( "{slash}" );
+            else if( c == '\\' )
                 converted += wxT( "{backslash}" );
             else if( c == '<' )
                 converted += wxT( "{lt}" );

eeschema/sch_plugins/kicad/sch_sexpr_plugin.cpp

@@ -1493,6 +1493,10 @@ LIB_SYMBOL* SCH_SEXPR_PLUGIN::LoadSymbol( const wxString& aLibraryPath, const wx
 
     LIB_SYMBOL_MAP::const_iterator it = m_cache->m_symbols.find( aSymbolName );
 
+    // We no longer escape '/' in symbol names, but we used to.
+    if( it == m_cache->m_symbols.end() && aSymbolName.Contains( '/' ) )
+        it = m_cache->m_symbols.find( EscapeString( aSymbolName, CTX_LEGACY_LIBID ) );
+
     if( it == m_cache->m_symbols.end() )
         return nullptr;
 

include/string_utils.h

@@ -53,6 +53,7 @@ enum ESCAPE_CONTEXT
 {
     CTX_NETNAME,
     CTX_LIBID,
+    CTX_LEGACY_LIBID,
     CTX_IPC,
     CTX_QUOTED_STR,
     CTX_JS_STR,