I read your in commit-message on source-changes several days ago about the
problem with __dead not working. __dead expands to volatile when using gcc
but newer versions of gcc2 use __attribute__((noreturn)) (I seem to recall
that there was a problem with ansi compilance and using const or volatile
qualifiers for fuunctions). I was under the impression that __dead should
still work, but apparently it doesn't.

When I looked at the header files I found that exit and abort in <stdlib.h>
do not have __attribute_((noreturn)), probably gcc has builtin noreturn
declarations for them, since otherwise you should have got warnings about
their not returning. I think that those declarations should be added
anyway.
In some header files __noreturn__ is used while in others noreturn is used,
both are valid, but __noreturn__ is safer from redefinition, since it
is in the implementation namespace. Perhaps all uses on noreturn
should be changed to __noreturn__


Since __dead does not work should it be removed from the header files ?

With the following patches yacc still compiles cleanly:

--- defs.h.orig	Sat Jul 26 04:08:10 1997
+++ defs.h	Wed Jul 30 18:24:42 1997
@@ -324,14 +324,14 @@
 extern void fatal __P((char *));
 
 extern void reflexive_transitive_closure __P((unsigned *, int));
-extern void done __P((int));
+extern void done __P((int)) __attribute__((noreturn));
 
 extern void fatal __P((char *));
 extern void no_space __P((void));
 extern void open_error(char *);
 extern void unexpected_EOF __P((void));
 extern void print_pos __P((char *, char *));
-extern __dead void syntax_error __P((int, char *, char *));
+extern void syntax_error __P((int, char *, char *)) __attribute__((noreturn));
 extern void unterminated_comment __P((int, char *, char *));
 extern void unterminated_string __P((int, char *, char *));
 extern void unterminated_text __P((int, char *, char *));
--- reader.c.orig	Sat Jul 26 04:08:12 1997
+++ reader.c	Wed Jul 30 17:46:21 1997
@@ -355,7 +355,6 @@
     }
     syntax_error(lineno, line, t_cptr);
     /*NOTREACHED*/
-    exit(1);
 }
 
 
--- main.c.orig	Sat Jul 26 04:08:11 1997
+++ main.c	Wed Jul 30 17:49:26 1997
@@ -116,7 +116,6 @@
 int main __P((int, char *[]));
 
 void onintr __P((int));
-__dead void done __P((int));
 void set_signals __P((void));
 void usage __P((void));
 void getargs __P((int, char *[]));
@@ -124,7 +123,7 @@
 void create_file_names __P((void));
 void open_files __P((void));
 
-__dead void
+void
 done(k)
 int k;
 {
@@ -467,5 +466,4 @@
     output();
     done(0);
     /*NOTREACHED*/
-    exit(0);
 }