Fix passing of undefined variables of unbridgeable foreign types

livecodefraser · livecodefraser · commit c2b03488d9b3 · 2016-09-08T16:41:51.000+01:00
The case of unbridgeable foreign types (like pointer) wasn't handled so
optional forms of these types weren't usable as parameters as they'd
fail due to the lack of bridging from undefined -&gt; pointer.
diff --git a/libscript/src/script-execute.cpp b/libscript/src/script-execute.cpp
@@ -534,18 +534,27 @@ MCScriptExecuteContext::ConvertToResolvedType(MCValueRef p_value,
 	}
 	else if (t_to_desc != nil)
 	{
-		// Export the foreign value
-		if (!MCForeignValueExport(p_to_type.type,
-								  p_value,
-								  (MCForeignValueRef&)r_new_value))
-		{
-			Rethrow();
-			return false;
-		}
-	}
-	else
-	{
-		r_new_value = MCValueRetain(p_value);
+        // If the foreign-typed slot is optional and the value is undefined,
+        // don't try to export. This allows optional foreign slots to be set to
+        // undefined when the type has no bridging type; without this, it is not
+        // possible to set these slots to undefined!
+        if (t_to_desc->doexport == nil &&
+            p_to_type.is_optional &&
+            p_value == kMCNull)
+        {
+            r_new_value = MCValueRetain(kMCNull);
+        }
+        else
+        {
+            // Export the foreign value
+            if (!MCForeignValueExport(p_to_type.type,
+                                      p_value,
+                                      (MCForeignValueRef&)r_new_value))
+            {
+                Rethrow();
+                return false;
+            }
+        }
 	}
 	
 	return true;
