Named symbol references.

Discussed in:
http://lists.gnu.org/archive/html/bison-patches/2009-01/msg00000.html
http://lists.gnu.org/archive/html/bison-patches/2009-02/msg00002.html
http://lists.gnu.org/archive/html/bison-patches/2009-03/msg00009.html

	* src/parse-gram.y: Add new syntax (named_ref.opt).
	* src/reader.c: Store named refs in symbol lists.
	* src/reader.h: New argument for symbol_append and
	action_append functions.
	* src/scan-code.h: Add new field (named_ref) into
	code_props data structure. Keeps named ref of midrule
	actions.
	* src/scan-code.l: Support for named refs in semantic
	action code. New function 'parse_named_ref'.
	* src/scan-gram.l: Support bracketed id.
	* src/symlist.c: Store named refs in symbol lists.
	* src/symlist.h: New field in symbol list: named_ref.
	* src/named-ref.h: New file, a struct for named_ref.
	* src/named-ref.c: New file, named_ref_new function.
	* src/Makefile.am: Add two new files.
	* tests/testsuite.at: Include new test group:
	* tests/named-refs.at: this new file.

src/symlist.h

@@ -23,6 +23,7 @@
 # include "location.h"
 # include "scan-code.h"
 # include "symtab.h"
+# include "named-ref.h"
 
 /* A list of symbols, used during the parsing to store the rules.  */
 typedef struct symbol_list
@@ -48,6 +49,9 @@ typedef struct symbol_list
   } content;
   location location;
 
+  /* Proper location of the symbol, not all the rule */
+  location sym_loc;
+
   /* If this symbol is the generated lhs for a midrule but this is the rule in
      whose rhs it appears, MIDRULE = a pointer to that midrule.  */
   struct symbol_list *midrule;
@@ -69,6 +73,9 @@ typedef struct symbol_list
   int merger;
   location merger_declaration_location;
 
+  /* Named reference. */
+  named_ref *named_ref;
+
   /* The list.  */
   struct symbol_list *next;
 } symbol_list;