Fix for Cygwin/GSlice problem

[Ken Brown <kbrown@cornell.edu>]

[-- Attachment #1: Type: text/plain, Size: 649 bytes --]

The attached patch fixes a longstanding problem with the Gtk+ build of 
emacs in Cygwin.  The problem is described in etc/PROBLEMS ("Emacs 
compiled with Gtk+ crashes on startup on Cygwin"), along with a 
workaround.  The patch simply incorporates that workaround into the 
emacs code.  I tried to do this so that the Cygwin-specific part is 
hidden in src/s/cygwin.h; it's conceivable that there are other systems 
where something similar would be useful.

The patch also removes the description of the problem from etc/PROBLEMS 
and removes a configuration warning.

Please apply the patch if it's OK, or tell me how to improve it.

Thanks.

Ken


[-- Attachment #2: gslice.patch --]
[-- Type: text/plain, Size: 2698 bytes --]

--- origsrc/emacs/src/s/cygwin.h	2009-11-20 23:50:36.000000000 -0500
+++ src/emacs/src/s/cygwin.h	2009-12-08 07:05:57.758985600 -0500
@@ -126,6 +126,12 @@ along with GNU Emacs.  If not, see <http
 /* Virtual addresses of pure and impure space can vary, as on Windows.  */
 #define VIRT_ADDR_VARIES
 
+/* Emacs supplies its own malloc, but glib (part of Gtk+) calls
+   memalign and on Cygwin, that becomes the Cygwin supplied memalign.
+   As malloc is not the Cygwin malloc, the Cygwin memalign always
+   returns ENOSYS.  A workaround is to set G_SLICE=always-malloc. */
+#define G_SLICE_ALWAYS_MALLOC
+
 /* the end */
 
 /* arch-tag: 5ae7ba00-83b0-4ab3-806a-3e845779191b
--- origsrc/emacs/src/emacs.c	2009-11-17 03:21:34.000000000 -0500
+++ src/emacs/src/emacs.c	2009-12-08 07:05:57.769000000 -0500
@@ -785,6 +785,9 @@ bug_reporting_address ()
 int
 main (int argc, char **argv)
 {
+# if defined (USE_GTK) && defined (G_SLICE_ALWAYS_MALLOC)
+  setenv("G_SLICE", "always-malloc", 1);
+#endif
 #if GC_MARK_STACK
   Lisp_Object dummy;
 #endif
--- origsrc/emacs/configure.in	2009-11-21 10:40:31.000000000 -0500
+++ src/emacs/configure.in	2009-12-08 07:05:57.809057600 -0500
@@ -3026,16 +3026,6 @@ fi
 
 echo
 
-if test "$USE_X_TOOLKIT" = GTK; then
-  case "$canonical" in
-  *cygwin*)
-    echo "There are known problems with Emacs and Gtk+ on cygwin, so you
-  will probably get a crash on startup.  If this happens, please use another
-  toolkit for Emacs.  See etc/PROBLEMS for more information."
-  ;;
-  esac
-fi
-
 if test "$HAVE_NS" = "yes"; then
    echo
    echo "You must run \"make install\" in order to test the built application.
--- origsrc/emacs/etc/PROBLEMS	2009-11-20 16:46:28.000000000 -0500
+++ src/emacs/etc/PROBLEMS	2009-12-08 07:08:07.655768000 -0500
@@ -244,28 +244,6 @@ frame on another X display, then a Gtk+ 
 server that results in an endless loop.  This is not fixed in any known
 Gtk+ version (2.14.4 being current).
 
-** Emacs compiled with Gtk+ crashes on startup on Cygwin.
-
-A typical error message is
-  ***MEMORY-ERROR***: emacs[5172]: GSlice: failed to allocate 504 bytes
-  (alignment: 512): Function not implemented
-
-Emacs supplies its own malloc, but glib (part of Gtk+) calls memalign and on
-Cygwin, that becomes the Cygwin supplied memalign.  As malloc is not the
-Cygwin malloc, the Cygwin memalign always returns ENOSYS.
-
-One workaround is to set G_SLICE=always-malloc before starting emacs.
-For example, in bash,
-
-  G_SLICE=always-malloc emacs
-
-or put
-
-  export G_SLICE=always-malloc
-
-in one of the bash startup files.  This also has to be done before
-building emacs on Cygwin with Gtk+.
-
 * General runtime problems
 
 ** Lisp problems