Parse the config declarations and report they will be ignored.

This patch adds code to parse config declarations and reports
that they are not currently supported and will be ignored.

parse.y

@@ -719,6 +719,7 @@ delay_value_simple
 description
   : module
   | udp_primitive
+  | config_declaration
   | nature_declaration
   | discipline_declaration
   | KK_attribute '(' IDENTIFIER ',' STRING ',' STRING ')'
@@ -783,6 +784,54 @@ nature_item
       { delete[] $3; }
   ;
 
+config_declaration
+  : K_config IDENTIFIER ';'
+    K_design lib_cell_identifiers ';'
+    list_of_config_rule_statements
+    K_endconfig
+      { cerr << @1 << ": sorry: config declarations are not supported and "
+                "will be skipped." << endl;
+	delete[] $2;
+      }
+  ;
+
+lib_cell_identifiers
+  : /* The BNF implies this can be blank, but I'm not sure exactly what
+     * this means. */
+  | lib_cell_identifiers lib_cell_id
+  ;
+
+list_of_config_rule_statements
+  : /* config rules are optional. */
+  | list_of_config_rule_statements config_rule_statement
+  ;
+
+config_rule_statement
+  : K_default K_liblist list_of_libraries ';'
+  | K_instance hierarchy_identifier K_liblist list_of_libraries ';'
+      { delete $2; }
+  | K_instance hierarchy_identifier K_use lib_cell_id opt_config ';'
+      { delete $2; }
+  | K_cell lib_cell_id K_liblist list_of_libraries ';'
+  | K_cell lib_cell_id K_use lib_cell_id opt_config ';'
+  ;
+
+opt_config
+  : /* The use clause takse an optional :config. */
+  | ':' K_config
+
+lib_cell_id
+  : IDENTIFIER
+      { delete[] $1; }
+  | IDENTIFIER '.' IDENTIFIER
+      { delete[] $1; delete[] $3; }
+  ;
+
+list_of_libraries
+  : /* A NULL library means use the parents cell library. */
+  | list_of_libraries IDENTIFIER
+      { delete[] $2; }
+
 drive_strength
 	: '(' dr_strength0 ',' dr_strength1 ')'
 		{ $$.str0 = $2.str0;