%interface family of macros no longer add variable wrappers

The getter/setter methods used for wrapping methods are no longer
added to the interface class.

Closes #1524

Also add in testcase for enums.

CHANGES.current

@@ -7,6 +7,15 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-03-12: wsfulton
+            #1524 %interface family of macros no longer contain the getter/setter
+            methods for wrapping variables. The interface only contains
+            virtual and non-virtual instance methods, that is, no static methods.
+            Enums are also no longer added to the interface (affects Java only where
+            they were missing from the proxy class, C# never had them in the interface).
+
+            *** POTENTIAL INCOMPATIBILITY ***
+
 2022-03-12: wsfulton
             #1277 Fixes for the family of %interface macros, %interface,
             %interface_impl and %interface_custom fixes for overloaded methods

Doc/Manual/Java.html

@@ -3546,6 +3546,12 @@ will be excluded from the interface and there will not be an additional method
 added to the proxy class implementing that interface.
 </p>
 
+<p>
+The Java interface only ever contains virtual and non-virtual instance methods from the wrapped C++ class.
+Any static methods, enums or variables in the wrapped C++ class are not supported and are not added to the interface.
+They are of course still available in the Java proxy class.
+</p>
+
 <p>
 Wherever a class marked as an interface is used, such as the <tt>UseBases</tt> method in the example,
 the interface name is used as the type in the Java layer:

Examples/test-suite/csharp/multiple_inheritance_interfaces_runme.cs

@@ -83,5 +83,7 @@ public class multiple_inheritance_interfaces_runme {
     d.ia(10);
     d.ia("bye");
     d.ia("bye", false);
+
+    UndesirablesSwigImpl.UndesiredStaticMethod(UndesirablesSwigImpl.UndesiredEnum.UndesiredEnum1);
   }
 }

Examples/test-suite/java/multiple_inheritance_interfaces_runme.java

@@ -74,5 +74,7 @@ public class multiple_inheritance_interfaces_runme {
     d.ia(10);
     d.ia("bye");
     d.ia("bye", false);
+
+    UndesirablesSwigImpl.UndesiredStaticMethod(UndesirablesSwigImpl.UndesiredEnum.UndesiredEnum1);
   }
 }

Examples/test-suite/multiple_inheritance_interfaces.i

@@ -49,6 +49,33 @@ struct V : S {};
 struct W : T {};
 %}
 
+#if defined(SWIGJAVA) || defined(SWIGCSHARP)
+%interface_impl(Undesirables);
+#endif
+
+%inline %{
+// Don't put variables and enums into interface
+class Undesirables
+{
+public:
+  Undesirables() : UndesiredVariable() {}
+  virtual ~Undesirables() {}
+  virtual void Method(int i) = 0;
+
+  enum UndesiredEnum { UndesiredEnum1, UndesiredEnum2 };
+  static void UndesiredStaticMethod(UndesiredEnum e) {}
+  int UndesiredVariable;
+  static int UndesiredStaticVariable;
+  static const int UndesiredStaticConstVariable = 0;
+};
+
+int Undesirables::UndesiredStaticVariable = 0;
+
+struct UndesirablesDerived : Undesirables {
+  virtual void Method(int i) {}
+};
+%}
+
 #if defined(SWIGJAVA) || defined(SWIGCSHARP)
 %interface_impl(BaseOverloaded);
 #endif

Source/Modules/csharp.cxx

@@ -2323,7 +2323,7 @@ public:
     String *pre_code = NewString("");
     String *post_code = NewString("");
     String *terminator_code = NewString("");
-    bool is_interface = GetFlag(parentNode(n), "feature:interface")
+    bool is_interface = GetFlag(parentNode(n), "feature:interface") && !checkAttribute(n, "kind", "variable")
       && !static_flag && Getattr(n, "interface:owner") == 0;
 
     if (!proxy_flag)

Source/Modules/java.cxx

@@ -2459,7 +2459,7 @@ public:
     bool setter_flag = false;
     String *pre_code = NewString("");
     String *post_code = NewString("");
-    bool is_interface = GetFlag(parentNode(n), "feature:interface")
+    bool is_interface = GetFlag(parentNode(n), "feature:interface") && !checkAttribute(n, "kind", "variable")
       && !static_flag && Getattr(n, "interface:owner") == 0;
 
     if (!proxy_flag)