chore: Explicitly re-implement exploit

Author: Stubbjax

Core/GameEngine/Include/Common/GameDefines.h

@@ -21,6 +21,10 @@
 // Note: Retail compatibility must not be broken before this project officially does.
 // Use RETAIL_COMPATIBLE_CRC and RETAIL_COMPATIBLE_XFER_SAVE to guard breaking changes.
 
+#ifndef RETAIL_COMPATIBLE_BUG
+#define RETAIL_COMPATIBLE_BUG (1) // Retain bugs present in retail Generals 1.08 and Zero Hour 1.04
+#endif
+
 #ifndef RETAIL_COMPATIBLE_CRC
 #define RETAIL_COMPATIBLE_CRC (1) // Game is expected to be CRC compatible with retail Generals 1.08, Zero Hour 1.04
 #endif

GeneralsMD/Code/GameEngine/Source/GameClient/SelectionInfo.cpp

@@ -374,6 +374,15 @@ Bool addDrawableToList( Drawable *draw, void *userData )
       return FALSE;
   }
 
+#if RETAIL_COMPATIBLE_BUG
+	// In retail, hidden objects such as passengers are included here when drag-selected, which causes
+	// enemy selection logic to exit early (only 1 enemy unit can be selected at a time). Some players
+	// exploit this bug to determine if a transport contains passengers and consider this an important
+	// feature and an advanced skill to pull off, so we must leave the exploit.
+	if (draw->getObject() && draw->getObject()->getContain() && draw->getObject()->getContain()->getContainCount() > 0)
+		pds->drawableListToFill->push_back(draw); // Just add the unit twice to prevent enemy selections
+#endif
+
 	pds->drawableListToFill->push_back(draw);
 	return TRUE;
 }