--- contrib/tools/bison/lib/obstack.h	(ef06a7dccff68bd15f669606131c541d158d4b1a)
+++ contrib/tools/bison/lib/obstack.h	(1efd2cc9274f1f5a222e759093d27c8d38825028)
@@ -511,4 +511,8 @@ __extension__                                                           \
 }       /* C++ */
 #endif
 
+#if !defined(obstack_printf)
+int obstack_printf(struct obstack *obs, const char *format, ...);
+#endif
+
 #endif /* _OBSTACK_H */
--- contrib/tools/bison/lib/obstack_printf.c	(ef06a7dccff68bd15f669606131c541d158d4b1a)
+++ contrib/tools/bison/lib/obstack_printf.c	(1efd2cc9274f1f5a222e759093d27c8d38825028)
@@ -26,6 +26,8 @@
 #include <stdarg.h>
 #include <stdlib.h>
 
+int obstack_vprintf(struct obstack *obs, const char *format, va_list args);
+
 /* Grow an obstack with formatted output.  Return the number of bytes
    added to OBS.  No trailing nul byte is added, and the object should
    be closed with obstack_finish before use.