%interface regression fix for multiple inheritance and common bases

Regressio introduced in 7592722.

Closes #2875

CHANGES.current

@@ -7,6 +7,10 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.3.0 (in progress)
 ===========================
 
+2024-09-07: wsfulton
+            #2875 Fix swig-4.1.0 regression using the %interface family of macros
+            for multiple inheritance and common bases.
+
 2024-09-06: olly
 	    [Python] Stop documenting to define SWIG_FILE_WITH_INIT - this does
 	    not actually do anything (and apparently never has!)

Examples/test-suite/java/multiple_inheritance_interfaces_runme.java

@@ -68,6 +68,13 @@ public class multiple_inheritance_interfaces_runme {
     checkBaseAndInterfaces(V.class, false, "S", new String[] {});
     checkBaseAndInterfaces(W.class, false, "T", new String[] {});
 
+    checkBaseAndInterfaces(IV1SwigInterface.class, true, "", new String[] {"IA"});
+    checkBaseAndInterfaces(IV2SwigInterface.class, true, "", new String[] {"IA"});
+    checkBaseAndInterfaces(IV1.class, false, "", new String[] {"IV1SwigInterface", "IA"});
+    checkBaseAndInterfaces(IV2.class, false, "", new String[] {"IV2SwigInterface", "IA"});
+    checkBaseAndInterfaces(V3.class, false, "", new String[] {"V3SwigInterface", "IV1SwigInterface", "IA", "IV2SwigInterface"});
+    checkBaseAndInterfaces(V3SwigInterface.class, true, "", new String[] {"IV1SwigInterface", "IV2SwigInterface"});
+
     // overloaded methods check
     D d = new D();
     d.ia();

Examples/test-suite/multiple_inheritance_interfaces.i

@@ -49,6 +49,17 @@ struct V : S {};
 struct W : T {};
 %}
 
+#if defined(SWIGJAVA) || defined(SWIGCSHARP)
+%interface(IV1)
+%interface(IV2)
+%interface(V3)
+#endif
+%inline %{
+struct IV1 : virtual IA {};
+struct IV2 : virtual IA {};
+struct V3 : IV1, IV2 {};
+%}
+
 #if defined(SWIGJAVA) || defined(SWIGCSHARP)
 %interface_impl(Undesirables);
 #endif

Source/DOH/base.c

@@ -207,7 +207,8 @@ int DohCmp(const DOH *obj1, const DOH *obj2) {
   b2info = b2->type;
   if ((b1info == b2info) && (b1info->doh_cmp))
     return (b1info->doh_cmp) (b1, b2);
-  return 1;
+  /* finally compare pointers */
+  return b1 < b2 ? -1 : b1 == b2 ? 0 : 1;
 }
 
 /* -----------------------------------------------------------------------------

Source/Modules/interface.cxx

@@ -64,8 +64,7 @@ static List *collect_interface_methods(Node *n) {
 
 static void collect_interface_bases(List *bases, Node *n) {
   if (GetFlag(n, "feature:interface")) {
-    String *name = Getattr(n, "interface:name");
-    if (!Getattr(bases, name))
+    if (!Swig_item_in_list(bases, n))
       Append(bases, n);
   }
 
@@ -82,10 +81,11 @@ static void collect_interface_bases(List *bases, Node *n) {
 /* -----------------------------------------------------------------------------
  * collect_interface_base_classes()
  *
- * Create a hash containing all the classes up the inheritance hierarchy
+ * Create a list containing all the classes up the inheritance hierarchy
  * marked with feature:interface (including this class n).
  * Stops going up the inheritance chain as soon as a class is found without
  * feature:interface.
+ * Remove duplicate bases (in the event of multiple inheritance).
  * The idea is to find all the base interfaces that a class must implement.
  * ----------------------------------------------------------------------------- */
 

Source/Swig/misc.c

@@ -1436,21 +1436,23 @@ int Swig_is_generated_overload(Node *n) {
 /* -----------------------------------------------------------------------------
  * Swig_item_in_list()
  *
- * If the input name is the name of an item in the list, return the item
+ * If the input item is in the list, return the item.
+ * Note: uses DohCmp for comparisons so for a List of String *, Strcmp is ultimately
+ * used for item comparisons to determine if a string is in the list.
  * ----------------------------------------------------------------------------- */
 
-Node *Swig_item_in_list(List *list, const_String_or_char_ptr name) {
-  Node *item = 0;
+Node *Swig_item_in_list(List *list, const DOH *item) {
+  Node *found_item = 0;
   if (list) {
     Iterator it;
     for (it = First(list); it.item; it = Next(it)) {
-      if (Strcmp(name, it.item) == 0) {
-	item = it.item;
+      if (DohCmp(item, it.item) == 0) {
+	found_item = it.item;
 	break;
       }
     }
   }
-  return item;
+  return found_item;
 }
 
 /* -----------------------------------------------------------------------------

Source/Swig/swig.h

@@ -343,7 +343,7 @@ extern int        ParmList_is_compactdefargs(ParmList *p);
 
   extern int Swig_value_wrapper_mode(int mode);
   extern int Swig_is_generated_overload(Node *n);
-  extern Node *Swig_item_in_list(List *list, const String *name);
+  extern Node *Swig_item_in_list(List *list, const DOH *item);
 
   typedef enum { EMF_STANDARD, EMF_MICROSOFT } ErrorMessageFormat;