--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lwlib/xt-wrappers.h	Wed Oct 29 04:06:33 2008 +0900
@@ -0,0 +1,103 @@
+/* Wrappers for Xt functions and macros
+
+   Copyright (C) 2008 Free Software Foundation
+
+This file is part of XEmacs.
+
+XEmacs is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+XEmacs is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+You should have received a copy of the GNU General Public License
+along with XEmacs; see the file COPYING.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* Synched up with: Not in FSF. */
+
+/* Original author: Stephen J. Turnbull for 21.5.29 */
+
+/* Generic utility macros, including coping with G++ whining.
+   Used in lwlib via lwlib.h and X consoles via console-x.h.
+
+   We would prefer to find another way to shut up G++.  The issue is that
+   recent versions of the C++ standard deprecate implicit conversions
+   across function boundaries like
+
+   typedef char *String;
+   void foo (String string);
+   foo ("bar");
+
+   because "bar" should be allowed to be a read-only array of chars.  But of
+   course lots of legacy code (== X11) declares things as char * and expects
+   to assign literal strings to them.  Now, the typedef in the example is
+   important because in G++ 4.3.2 at least, this
+
+   void foo (const String string);
+   foo ("bar");
+
+   does not work as expected!  G++ still warns about this construct.  However,
+   if foo is declared
+
+   void foo (const char *string);
+
+   G++ does not complain.  (#### There are two possibilities I can think of.
+   (a) G++ is buggy.  (b) "const String" is interpreted as "char * const".)
+
+   The upshot is that to avoid warnings with Xt's String typedef, we need to
+   arrange to cast literal strings to String, rather than use "const String"
+   in declarations.  (My <X11/Intrinsic.h> says that the actual internal
+   typedef used is _XtString, so that String can be #define'd to something
+   else for the purposes of C++.  But that doesn't really help us much.)
+
+   It's not very satisfactory to do it this way -- it would be much better to
+   have const Strings where they make sense -- but it does eliminate a few
+   hundred warnings from the C++ build.  And in any case we don't control the
+   many objects declared with String components in Intrinsic.h.  The remaining
+   issues are the WEXTTEXT macro used in src/emacs.c, and Emacs.ad.h (where
+   instead of String we use const char * in src/event-Xt.c in the array that
+   #includes it).
+*/
+
+#ifndef INCLUDED_xt_wrappers_h_
+#define INCLUDED_xt_wrappers_h_
+
+/* Wrap XtResource, with the same elements as arguments.
+   The cast to String shuts up G++ 4.3's whining about const char *.
+   The invocation of sizeof should be pretty safe, and the cast to XtPointer
+   surely is, since that's how that member of XtResource is declared.  It
+   doesn't hide potential problems, because XtPointer is a "generic" type in
+   any case -- the actual object will have a different type, that will be
+   cast to XtPointer. */
+
+#define Xt_RESOURCE(name,_class,intrepr,type,member,extrepr,value)	\
+  { (String) name, (String) _class, (String) intrepr, sizeof(type),	\
+    member, extrepr, (XtPointer) value }
+
+/* Wrap XtSetArg, with the same arguments.
+   The cast to String shuts up G++ 4.3's whining about const char *. */
+
+#define Xt_SET_ARG(al, resource, x) do {	\
+    XtSetArg ((al), (String) (resource), (x));	\
+  } while (0)
+
+/* Convenience macros for getting/setting one resource value. */
+
+#define Xt_SET_VALUE(widget, resource, value) do {	\
+  Arg al;						\
+  Xt_SET_ARG (al, resource, value);			\
+  XtSetValues (widget, &al, 1);				\
+} while (0)
+
+#define Xt_GET_VALUE(widget, resource, location) do {	\
+  Arg al;						\
+  Xt_SET_ARG (al, resource, location);			\
+  XtGetValues (widget, &al, 1);				\
+} while (0)
+
+#endif /* INCLUDED_xt_wrappers_h_ */