Report a cppia new with nothing to construct as a link failure.

src/hx/cppia/Cppia.cpp

@@ -1507,6 +1507,13 @@ struct NewExpr : public CppiaDynamicExpr
       if (!type->cppiaClass && type->haxeClass.mPtr)
          constructor = type->haxeClass.mPtr->mConstructArgs;
 
+      // Nothing to construct: runObject and genCode would dereference the null cppiaClass.
+      if (!type->arrayType && !constructor && !type->cppiaClass)
+      {
+         CPPIALOG("Could not link new %s\n", type->name.c_str());
+         throw "Bad link";
+      }
+
       LinkExpressions(args,inModule);
       return this;
    }

test/cppia/ClientUnlinked.hx

@@ -0,0 +1,13 @@
+// The host does not have this class: a module constructing it must fail to link.
+extern class Unlinked
+{
+   public function new();
+}
+
+class ClientUnlinked
+{
+   public static function main()
+   {
+      new Unlinked();
+   }
+}

test/cppia/cases/TestCommon.hx

@@ -59,6 +59,12 @@ class TestCommon extends Test {
         Assert.equals(2, Common.callbackSet, 'Bad cppia closure');
     }
 
+    function testNewOfUnlinkedClass() {
+        final source = sys.io.File.getBytes('bin/unlinked.cppia');
+
+        Assert.raises(() -> cpp.cppia.Module.fromData(source.getData()), String, 'Linked a new of a class the host does not have');
+    }
+
     @:depends(testStatus)
     function testInterfaceCalling() {
         final obj : IFoo = Type.createInstance(Type.resolveClass('ClientFoo'), []);

test/cppia/compile-client.hxml

@@ -1,3 +1,8 @@
 -m Client
 -D dll_import=host_classes.info
---cppia bin/client.cppia
+--cppia bin/client.cppia
+
+--next
+
+-m ClientUnlinked
+--cppia bin/unlinked.cppia