Fix Java swigReleaseOwnership() and swigTakeOwnership() regression

Fixes segfault when using non-director classes.
Restores a dynamic_cast which was previously removed.
The dynamic_cast is not needed for the swig_connect_director call ...
we'll have to find another solution for #449 for Java.

Closes #1184

CHANGES.current

@@ -7,6 +7,10 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.0.0 (in progress)
 ===========================
 
+2018-03-09: fultonwi
+            [Java] #1184 Fix swigReleaseOwnership() and swigTakeOwnership() regression
+            for non-director classes. Restores a dynamic_cast which was previously removed.
+
 2018-03-07: llongi
 	    Github PR #1166 - Fix preprocessor handling of macros with commas
 	    in a // comment.

Examples/test-suite/common.mk

@@ -194,6 +194,7 @@ CPP_TEST_CASES += \
 	director_nspace_director_name_collision \
 	director_overload \
 	director_overload2 \
+	director_ownership \
 	director_pass_by_value \
 	director_primitives \
 	director_property \

Examples/test-suite/director_ownership.i

@@ -0,0 +1,72 @@
+%module(directors="1") director_ownership
+
+// Github issue #1184
+
+%include "std_string.i"
+
+%feature("director") example::ContentBase;
+%feature("director") example::ContentDerived;
+
+%newobject example::make_content;
+
+%inline %{
+#include <string>
+
+namespace example
+{
+
+class ContentBase
+{
+public:
+    ContentBase() {}
+    virtual ~ContentBase() {}
+    virtual std::string get_name() const = 0;
+};
+
+
+class ContentDerived: public ContentBase
+{
+public:
+    ContentDerived():ContentBase() { m_name = "ContentDerived"; }
+    virtual ~ContentDerived() {}
+    virtual std::string get_name() const override { return m_name; }
+
+private:
+    std::string m_name;
+};
+
+
+class Container
+{
+public:
+    Container() { m_content = 0; }
+    ~Container()
+    {
+        clear_content();
+    }
+    // the container takes the ownership of the content
+    void set_content(ContentBase* content)
+    {
+        clear_content();
+        m_content = content;
+    }
+    ContentBase* get_content() { return m_content; }
+
+private:
+    void clear_content()
+    {
+        if(m_content)
+        {
+            delete m_content;
+            m_content = 0;
+        }
+    }
+    
+private:
+    ContentBase* m_content;
+};
+
+static ContentBase* make_content() { return new ContentDerived(); }
+
+} // namespace example
+%}

Examples/test-suite/java/director_ownership_runme.java

@@ -0,0 +1,42 @@
+import director_ownership.*;
+
+public class director_ownership_runme {
+
+  static {
+    try {
+      System.loadLibrary("director_ownership");
+    } catch (UnsatisfiedLinkError e) {
+      System.err.println("Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" + e);
+      System.exit(1);
+    }
+  }
+
+  public static void set_content_and_release(Container container, ContentBase content) {
+    content.swigReleaseOwnership();
+    container.set_content(content);
+  }
+
+  public static void main(String argv[]) {
+
+    Container container = new Container();
+
+    // make a content in java (cMemoryOwn true)
+    ContentBase content_java = new ContentDerived();
+
+    // make a content in c++ (cMemoryOwn true)
+    ContentBase content_cpp = director_ownership.make_content();
+
+    set_content_and_release(container, content_java);
+    if (!container.get_content().get_name().equals("ContentDerived"))
+      throw new RuntimeException("did not get ContentDerived");
+
+    // when swigReleaseOwnership() is called on content_cpp, swig tries a static_cast to director and calls the method
+    // director->swig_java_change_ownership. The content created in c++ native library is not a director, therefore a
+    // segfault may occur.
+    // With a check done using dynamic_cast this issue could be avoided.
+    set_content_and_release(container, content_cpp);
+    if (!container.get_content().get_name().equals("ContentDerived"))
+      throw new RuntimeException("did not get ContentDerived");
+  }
+}
+

Source/Modules/java.cxx

@@ -3763,15 +3763,16 @@ public:
         Printf(code_wrap->code, "  %s *obj = *((%s **)&objarg);\n", smartptr, smartptr);
         Printf(code_wrap->code, "  // Keep a local instance of the smart pointer around while we are using the raw pointer\n");
         Printf(code_wrap->code, "  // Avoids using smart pointer specific API.\n");
-        Printf(code_wrap->code, "  %s *director = static_cast<%s *>(obj->operator->());\n", dirClassName, dirClassName);
-    }
-    else {
+        Printf(code_wrap->code, "  %s *director = dynamic_cast<%s *>(obj->operator->());\n", dirClassName, dirClassName);
+    } else {
         Printf(code_wrap->code, "  %s *obj = *((%s **)&objarg);\n", norm_name, norm_name);
-        Printf(code_wrap->code, "  %s *director = static_cast<%s *>(obj);\n", dirClassName, dirClassName);
+        Printf(code_wrap->code, "  %s *director = dynamic_cast<%s *>(obj);\n", dirClassName, dirClassName);
     }
 
     Printf(code_wrap->code, "  (void)jcls;\n");
-    Printf(code_wrap->code, "  director->swig_java_change_ownership(jenv, jself, jtake_or_release ? true : false);\n");
+    Printf(code_wrap->code, "  if (director) {\n");
+    Printf(code_wrap->code, "    director->swig_java_change_ownership(jenv, jself, jtake_or_release ? true : false);\n");
+    Printf(code_wrap->code, "  }\n");
     Printf(code_wrap->code, "}\n");
 
     Wrapper_print(code_wrap, f_wrappers);