diff --git a/xpcom/typelib/xpidl/xpidl.h b/xpcom/typelib/xpidl/xpidl.h
index ea77f25db2a0..b2048b96dc7f 100644
--- a/xpcom/typelib/xpidl/xpidl.h
+++ b/xpcom/typelib/xpidl/xpidl.h
@@ -43,17 +43,18 @@
  * ## idiom, which allows us to pass through varargs calls.
  */
 #if !(LIBIDL_MAJOR_VERSION == 0 && LIBIDL_MINOR_VERSION == 6 && \
-      LIBIDL_MICRO_VERSION == 5)
+      LIBIDL_MICRO_VERSION == 5) && !defined(DEBUG_shaver)
 /*
- * This turns a varargs call to XPIDL_WARNING directly into a varargs call to
- * IDL_tree_warning.  The only tricky bit is that you must call XPIDL_WARNING
- * with extra parens, e.g. XPIDL_WARNING((foo, bar, "sil"))
+ * This turns a varargs call to XPIDL_WARNING directly into a varargs
+ * call to IDL_tree_warning or xpidl_tree_warning as appropriate.  The
+ * only tricky bit is that you must call XPIDL_WARNING with extra
+ * parens, e.g. XPIDL_WARNING((foo, bar, "sil"))
  *
- * Probably best removed when we leave 6.5.
-*/
+ * Probably best removed when we leave 6.5.  */
 #define XPIDL_WARNING(x) IDL_tree_warning##x
 #else
-#define XPIDL_WARNING(x) do { } while (0)
+extern void xpidl_tree_warning(IDL_tree p, int level, const char *fmt, ...);
+#define XPIDL_WARNING(x) xpidl_tree_warning##x
 #endif
 
 /*
@@ -196,4 +197,11 @@ xpidl_parse_iid(nsID *id, const char *str);
 gboolean
 verify_method_declaration(IDL_tree method_tree);
 
+/*
+ * Verify that a native declaration has an associated C++ expression, i.e. that
+ * it's of the form native <idl-name>(<c++-name>)
+ */
+gboolean
+check_native(TreeState *state);
+
 #endif /* __xpidl_h */
diff --git a/xpcom/typelib/xpidl/xpidl_header.c b/xpcom/typelib/xpidl/xpidl_header.c
index 12a798065354..9b13616ff3d8 100644
--- a/xpcom/typelib/xpidl/xpidl_header.c
+++ b/xpcom/typelib/xpidl/xpidl_header.c
@@ -487,26 +487,9 @@ attr_dcl(TreeState *state)
 static gboolean
 do_enum(TreeState *state)
 {
-    XPIDL_WARNING((state->tree, IDL_WARNING1,
-                   "enums not supported, enum \'%s\' ignored",
-                   IDL_IDENT(IDL_TYPE_ENUM(state->tree).ident).str));
-    return TRUE;
-#if 0
-    IDL_tree enumb = state->tree, iter;
-
-    fprintf(state->file, "enum %s {\n",
-            IDL_IDENT(IDL_TYPE_ENUM(enumb).ident).str);
-
-    for (iter = IDL_TYPE_ENUM(enumb).enumerator_list;
-         iter;
-         iter = IDL_LIST(iter).next) {
-        fprintf(state->file, "  %s%s\n", IDL_IDENT(IDL_LIST(iter).data).str,
-                IDL_LIST(iter).next ? ",": "");
-    }
-
-    fputs("};\n\n", state->file);
-    return TRUE;
-#endif
+    IDL_tree_error(state->tree, "enums not supported, "
+                   "see http://bugzilla.mozilla.org/show_bug.cgi?id=8781");
+    return FALSE;
 }
 
 static gboolean
@@ -542,8 +525,9 @@ do_const_dcl(TreeState *state)
                              name, (int) IDL_INTEGER(dcl->const_exp).value);
     } else {
         IDL_tree_error(state->tree,
-                       "const decl \'%s\' must be of type short or long",
+                       "const declaration \'%s\' must be of type short or long",
                        name);
+        return FALSE;
     }
     return TRUE;
 }
@@ -769,10 +753,11 @@ static gboolean
 codefrag(TreeState *state)
 {
     const char *desc = IDL_CODEFRAG(state->tree).desc;
-    if (strcmp(desc, "C++")) {
+    
+    if (strcmp(desc, "C++") && /* libIDL bug? */ strcmp(desc, "C++\r")) {
         XPIDL_WARNING((state->tree, IDL_WARNING1,
                        "ignoring '%%{%s' escape. "
-                       "(Use '%%{C++' to escape verbatim code.)", desc));
+                       "(Use '%%{C++' to escape verbatim C++ code.)", desc));
 
         return TRUE;
     }
@@ -785,8 +770,9 @@ nodeHandler *
 xpidl_header_dispatch(void)
 {
     static nodeHandler table[IDLN_LAST];
+    static gboolean initialized = FALSE;
 
-    if (!table[IDLN_NONE]) {
+    if (!initialized) {
         table[IDLN_NONE] = pass_1;
         table[IDLN_LIST] = list;
         table[IDLN_ATTR_DCL] = attr_dcl;
@@ -797,6 +783,8 @@ xpidl_header_dispatch(void)
         table[IDLN_CODEFRAG] = codefrag;
         table[IDLN_TYPE_DCL] = do_typedef;
         table[IDLN_CONST_DCL] = do_const_dcl;
+        table[IDLN_NATIVE] = check_native;
+        initialized = TRUE;
     }
 
     return table;
diff --git a/xpcom/typelib/xpidl/xpidl_idl.c b/xpcom/typelib/xpidl/xpidl_idl.c
index 70c14fdbf0db..dd7db88e2f29 100644
--- a/xpcom/typelib/xpidl/xpidl_idl.c
+++ b/xpcom/typelib/xpidl/xpidl_idl.c
@@ -104,14 +104,19 @@ static int
 msg_callback(int level, int num, int line, const char *file,
              const char *message)
 {
+    char *warning_message;
+
+    if (!file)
+        file = "<unknown file>";
+    warning_message = g_strdup_printf("%s:%d: %s\n", file, line, message);
+
 #ifdef XP_MAC
-    static char warning_message[1024];
-    sprintf(warning_message, "%s:%d: %s\n", file, line, message);
     mac_warning(warning_message);
 #else
-    /* XXX Mac */
-    fprintf(stderr, "%s:%d: %s\n", file, line, message);
+    fputs(warning_message, stderr);
 #endif
+
+    free(warning_message);
     return 1;
 }
 
@@ -888,3 +893,50 @@ verify_method_declaration(IDL_tree method_tree)
     }
     return TRUE;
 }
+
+/*
+ * Verify that a native declaration has an associated C++ expression, i.e. that
+ * it's of the form native <idl-name>(<c++-name>)
+ */
+gboolean
+check_native(TreeState *state)
+{
+    char *native_name;
+    /* require that native declarations give a native type */
+    if (IDL_NATIVE(state->tree).user_type) 
+        return TRUE;
+    native_name = IDL_IDENT(IDL_NATIVE(state->tree).ident).str;
+    IDL_tree_error(state->tree,
+                   "``native %s;'' needs C++ type: ``native %s(<C++ type>);''",
+                   native_name, native_name);
+    return FALSE;
+}
+
+/*
+ * Our own version of IDL_tree_warning, which we use when IDL_tree_warning
+ * would crash on us.
+ */
+void
+xpidl_tree_warning(IDL_tree p, int level, const char *fmt, ...)
+{
+    va_list ap;
+    char *msg, *file;
+    int lineno;
+
+    /* XXX need to check against __IDL_max_msg_level, no accessor */
+    va_start(ap, fmt);
+    msg = g_strdup_vprintf(fmt, ap);
+
+    if (p) {
+        file = p->_file;
+        lineno = p->_line;
+    } else {
+        file = NULL;
+        lineno = 0;
+    }
+
+    /* call our message callback, like IDL_tree_warning would */
+    msg_callback(level, 0 /* unused in callee */, lineno, file, msg);
+
+    va_end(ap);
+}
diff --git a/xpcom/typelib/xpidl/xpidl_typelib.c b/xpcom/typelib/xpidl/xpidl_typelib.c
index 2bb6c14bcea8..7cd76107fb2f 100644
--- a/xpcom/typelib/xpidl/xpidl_typelib.c
+++ b/xpcom/typelib/xpidl/xpidl_typelib.c
@@ -463,12 +463,7 @@ pass_1(TreeState *state)
     destroy_header:
         /* XXX XPT_DestroyHeader(HEADER(state)) */
 
-#ifdef DEBUG_shaver
-        fprintf(stderr, "writing typelib was %ssuccessful\n",
-                ok ? "" : "not ");
-#else
         ;   /* msvc would like a statement here */
-#endif
     }
 
     return ok;
@@ -853,18 +848,10 @@ handle_iid_is:
                       }
                   }
                   if (isID) {
-#ifdef DEBUG_shaver
-                      fprintf(stderr, "doing nsID for %s\n",
-                              IDL_IDENT(type).str);
-#endif
                       td->prefix.flags = TD_PNSIID | XPT_TDP_POINTER;
                       if(IDL_tree_property_get(type, "ref"))
                           td->prefix.flags |= XPT_TDP_REFERENCE;
                   } else {
-#ifdef DEBUG_shaver
-                      fprintf(stderr, "not doing nsID for %s\n",
-                              IDL_IDENT(type).str);
-#endif
                       td->prefix.flags = TD_VOID | XPT_TDP_POINTER;
                   }
                   break;
@@ -894,11 +881,12 @@ handle_iid_is:
                 }
                 IDL_tree_error(type, "can't handle %s ident in param list\n",
 #ifdef DEBUG_shaver
-                        IDL_NODE_TYPE_NAME(IDL_NODE_UP(type))
+                               /* XXX is this safe to use on Win now? */
+                               IDL_NODE_TYPE_NAME(IDL_NODE_UP(type))
 #else
-                        "that type of"
+                               "that type of"
 #endif
-                        );
+                               );
 #ifdef DEBUG_shaver
                 XPT_ASSERT(0);
 #endif
@@ -908,7 +896,8 @@ handle_iid_is:
           default:
             IDL_tree_error(type, "can't handle %s in param list\n",
 #ifdef DEBUG_shaver
-                        IDL_NODE_TYPE_NAME(IDL_NODE_UP(type))
+                           /* XXX is this safe to use on Win now? */
+                           IDL_NODE_TYPE_NAME(IDL_NODE_UP(type))
 #else
                         "that type"
 #endif
@@ -1035,6 +1024,7 @@ typelib_op_dcl(TreeState *state)
     IDL_tree iter;
     uint16 num_args = 0;
     uint8 op_flags = 0;
+    gboolean saw_retval = FALSE;
     gboolean op_notxpcom = (IDL_tree_property_get(op->ident, "notxpcom")
                             != NULL);
     gboolean op_noscript = (IDL_tree_property_get(op->ident, "noscript")
@@ -1070,9 +1060,22 @@ typelib_op_dcl(TreeState *state)
 
     for (num_args = 0, iter = op->parameter_dcls; iter;
          iter = IDL_LIST(iter).next, num_args++) {
-        if (!fill_pd_from_param(state, &meth->params[num_args],
-                                IDL_LIST(iter).data))
+        XPTParamDescriptor *pd = &meth->params[num_args];
+        if (!fill_pd_from_param(state, pd, IDL_LIST(iter).data))
             return FALSE;
+        if (pd->flags & XPT_PD_RETVAL) {
+            if (op->op_type_spec) {
+                IDL_tree_error(state->tree, 
+                               "can't have [retval] with non-void return type");
+                return FALSE;
+            }
+            if (saw_retval) {
+                IDL_tree_error(state->tree,
+                               "can't have more than one [retval] parameter");
+                return FALSE;
+            }
+            saw_retval = TRUE;
+        }
     }
 
     /* XXX unless [notxpcom] */
@@ -1286,6 +1289,7 @@ xpidl_typelib_dispatch(void)
       table[IDLN_INTERFACE] = typelib_interface;
       table[IDLN_CONST_DCL] = typelib_const_dcl;
       table[IDLN_TYPE_ENUM] = typelib_enum;
+      table[IDLN_NATIVE] = check_native;
       initialized = TRUE;
   }