DUP
| DT_KEY_SELF { $$ = dt_node_ident(DUP("self")); }
| DT_KEY_THIS { $$ = dt_node_ident(DUP("this")); }
type_specifier: DT_KEY_VOID { $$ = dt_decl_spec(CTF_K_INTEGER, DUP("void")); }
| DT_KEY_CHAR { $$ = dt_decl_spec(CTF_K_INTEGER, DUP("char")); }
| DT_KEY_INT { $$ = dt_decl_spec(CTF_K_INTEGER, DUP("int")); }
| DT_KEY_FLOAT { $$ = dt_decl_spec(CTF_K_FLOAT, DUP("float")); }
| DT_KEY_DOUBLE { $$ = dt_decl_spec(CTF_K_FLOAT, DUP("double")); }
$$ = dt_decl_spec(CTF_K_TYPEDEF, DUP("string"));