There is too much code duplication between %printer and %destructor.
We used to have two functions for each action: the first one for
destructors, the second one for printers. Factor using a
'code_props_type', and an array of code_props instead of two
members.
* src/symlist.h, src/symlist.c (symbol_list_destructor_set)
(symbol_list_printer_set): Fuse into...
(symbol_list_code_props_set): this.
* src/symtab.h, src/symtab.c (default_tagged_destructor)
(default_tagged_printer): Fuse into...
(default_tagged_code_props): this.
(default_tagless_destructor, default_tagless_printer)
(default_tagless_code_props): Likewise.
(code_props_type_string): new.
(symbol_destructor_set, symbol_destructor_get, semantic_type_destructor_set)
(default_tagged_destructor_set, default_tagless_destructor_set)
(symbol_printer_set, symbol_printer_get, semantic_type_printer_set)
(default_tagged_printer_set, default_tagless_printer_set): Replace by...
(symbol_code_props_set, symbol_code_props_get, semantic_type_code_props_set)
(default_tagged_code_props_set, default_tagless_code_props_set): these.
* src/parse-gram.y (grammar_declaration): Adjust.
* src/output.c (CODE_PROP, grammar_declaration): Ditto.
* src/reader.c (symbol_should_be_used): Ditto.
We used to raise an error if a symbol appears only in a %printer or
%destructor. Make it a warning.
* src/symtab.h (status): New enum.
(symbol): Replace the binary "declared" with the three-state "status".
Adjust dependencies.
* src/symtab.c (symbol_check_defined): Needed symbols are an error,
whereas "used" are simply warnings.
* src/symlist.c (symbol_list_destructor_set, symbol_list_printer): Set
symbol status to 'used' when associated to destructors or printers.
* input.at (Undeclared symbols used for a printer or destructor): New.
Victor SantetandAkim Demaille