[PATCH] gengtype: support empty GTY-marked structs

[David Malcolm <dmalcolm at redhat dot com>]

I'm attaching a patch which allows gengtype to handle GTY-marked structs
that have no fields.  These are useful for supporting the "have a
subclass for every gimple code" idea from:
  http://gcc.gnu.org/ml/gcc-patches/2013-11/msg00057.html
(and am bootstrapping a patch that does that, which needed this one for
gengtype to cope).

Successfully bootstrapped&regtested on x86_64-unknown-linux-gnu.

OK for trunk?

commit 030c6bd6856ee175adf7cf60cb44b2f2091360d0
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Mon Nov 4 21:21:23 2013 -0500

    gengtype: support empty structs
    
    gcc/
    	* gengtype-parse.c (struct_field_seq): Support empty structs.

diff --git a/gcc/gengtype-parse.c b/gcc/gengtype-parse.c
index f480503..8328e3a 100644
--- a/gcc/gengtype-parse.c
+++ b/gcc/gengtype-parse.c
@@ -730,7 +730,7 @@ declarator (type_p ty, const char **namep, options_p *optsp,
    (
    type bitfield ';'
    | type declarator bitfield? ( ',' declarator bitfield? )+ ';'
-   )+
+   )*
 
    Knows that such declarations must end with a close brace (or,
    erroneously, at EOF).
@@ -744,7 +744,7 @@ struct_field_seq (void)
   const char *name;
   bool another;
 
-  do
+  while (token () != '}' && token () != EOF_TOKEN)
     {
       ty = type (&opts, true);
 
@@ -787,7 +787,6 @@ struct_field_seq (void)
 	}
       while (another);
     }
-  while (token () != '}' && token () != EOF_TOKEN);
   return nreverse_pairs (f);
 }