Adding test case demonstrating issue where SWIG does not generate a correctly typed, upcasted shared_ptr for a template instantiation deriving from a base class

Author: etse-dignitas

Examples/test-suite/cpp11_shared_ptr_template_upcast.i

@@ -0,0 +1,88 @@
+%module cpp11_shared_ptr_template_upcast
+
+%{
+#include <memory>
+#include <string>
+%}
+
+%include <std_shared_ptr.i>
+%include <std_string.i>
+
+%{
+class Base {
+public:
+    Base() : value(0) {}
+    Base(int v) : value(v) {}
+    virtual ~Base() {}
+    
+    virtual int GetResult() = 0;
+    
+    int value;
+};
+
+class Derived : public Base {
+public:
+    Derived() : Base() {}
+    Derived(int v) : Base(v) {}
+    virtual ~Derived() {}
+    
+    int GetResult() { return value*2; }
+};
+
+template <class T> class Printable : virtual public T {
+public:
+    Printable(int param) : T(param) {}
+    ~Printable() {}
+
+    std::string GetFormatted() { return std::string("The formatted result is: ").append(std::to_string(this->GetResult())); }
+};
+
+std::shared_ptr<Printable<Derived> > MakePrintableDerived(int param) {
+    return std::make_shared<Printable<Derived> >(param);
+}
+
+%}
+
+%shared_ptr(Base);
+%shared_ptr(Derived);
+%shared_ptr(Printable<Derived>)
+
+class Base {
+public:
+    Base();
+    Base(int v);
+    virtual ~Base();
+    
+    virtual int GetResult() = 0;
+    
+    int value;
+};
+
+class Derived : public Base {
+public:
+    Derived();
+    Derived(int v);
+    virtual ~Derived();
+    
+    int GetResult();
+};
+
+/*
+    Contrived for this case (but valid for others, such as if Printable was to be a interface/abstract base class).
+    Virtual inheritance exposes whether SWIGSmartPtrUpcast generated a correctly typed shared pointer of the upcasted class type - if the pointer type is incorrect, this will result in 
+    a segmentation fault (on Windows, this could manifest as undefined behavior) when trying to access any member inherited from T through a shared_ptr<Printable<T> >.
+*/
+template <class T> class Printable : virtual public T {
+public:
+    Printable(int param);
+    ~Printable();
+
+    std::string GetFormatted();
+};
+
+std::shared_ptr<Printable<Derived> > MakePrintableDerived(int param);
+
+
+%template(PrintableDerived) Printable<Derived>;
+
+

Examples/test-suite/java/Makefile.in

@@ -52,6 +52,7 @@ CPP11_TEST_CASES = \
 	cpp11_shared_ptr_const \
 	cpp11_shared_ptr_nullptr_in_containers \
 	cpp11_shared_ptr_overload \
+	cpp11_shared_ptr_template_upcast \
 	cpp11_shared_ptr_upcast \
 	cpp11_std_unordered_map \
 	cpp11_std_unordered_set \

Examples/test-suite/java/cpp11_shared_ptr_template_upcast_runme.java

@@ -0,0 +1,25 @@
+
+// This is the cpp11_shared_ptr_template_upcast runtime testcase. It checks that SWIG generates the appropriate, upcasted shared_ptr type for a template instantiation deriving from a base class.
+// In this case, the expected behavior is that given a cptr (underlying type shared_ptr<Printable<Derived> >), PrintableDerived_SWIGSmartPtrUpcast returns a cptr 
+// (underlying type std::shared_ptr< Derived >).
+
+import cpp11_shared_ptr_template_upcast.*;
+
+public class cpp11_shared_ptr_template_upcast_runme {
+
+  static {
+    try {
+	System.loadLibrary("cpp11_shared_ptr_template_upcast");
+    } 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 main(String argv[]) {
+    PrintableDerived pd = cpp11_shared_ptr_template_upcast.MakePrintableDerived(20);
+    pd.GetResult();
+    pd.GetFormatted();
+  }
+}
+