In file included from ./lib/readline/readline.h:38,
                 from shell.c:85:
./lib/readline/tilde.h:1:1: error: expected identifier or ‘(’ before ‘.’ token
    1 | ../tilde/tilde.h
      | ^
./lib/readline/readline.h:61:18: error: field ‘what’ has incomplete type
   61 |   enum undo_code what;          /* Delete, Insert, Begin, End. */
      |                  ^~~~