--- a/src/process-unix.c	Mon Aug 13 11:35:05 2007 +0200
+++ b/src/process-unix.c	Mon Aug 13 11:36:19 2007 +0200
@@ -1407,9 +1407,9 @@
 try_to_initialize_subtty (struct unix_process_data *upd)
 {
   if (upd->pty_flag
-      && (upd->subtty = -1 || ! isatty (upd->subtty))
+      && (upd->subtty == -1 || ! isatty (upd->subtty))
       && STRINGP (upd->tty_name))
-    upd->subtty = open (XSTRING_DATA (upd->tty_name), O_RDWR, 0);
+    upd->subtty = open ((char *) XSTRING_DATA (upd->tty_name), O_RDWR, 0);
 }
 
 /* Send signal number SIGNO to PROCESS.
@@ -1475,9 +1475,21 @@
      ioctl TIOCGPGRP it is supposed to obsolete.  Sometimes we have to
      use TIOCGPGRP on the master end, sometimes the slave end
      (probably an AIX bug).  So we better get a fd for the slave if we
-     haven't got it yet.  On some systems none of these work, so then
-     we just fall back to the non-current_group behavior and kill the
-     process group of the child. */
+     haven't got it yet.
+
+     Anal operating systems like SGI Irix and Compaq Tru64 adhere
+     strictly to the letter of the law, so our hack doesn't work.
+     The following fragment from an Irix header file is suggestive:
+
+     #ifdef __notdef__
+     // this is not currently supported
+     #define TIOCSIGNAL      (tIOC|31)       // pty: send signal to slave
+     #endif
+
+     On those systems where none of our tricks work, we just fall back
+     to the non-current_group behavior and kill the process group of
+     the child.
+  */
   if (current_group)
     {
       try_to_initialize_subtty (d);