In file included from ethtool-user.c:9:
ethtool-user.h:23:43: warning: ‘enum ethtool_header_flags’ declared inside parameter list will not be visible outside of this definition or declaration
   23 | const char *ethtool_header_flags_str(enum ethtool_header_flags value);
      |                                           ^~~~~~~~~~~~~~~~~~~~
ethtool-user.c:99:43: warning: ‘enum ethtool_header_flags’ declared inside parameter list will not be visible outside of this definition or declaration
   99 | const char *ethtool_header_flags_str(enum ethtool_header_flags value)
      |                                           ^~~~~~~~~~~~~~~~~~~~
ethtool-user.c:99:64: error: parameter 1 (‘value’) has incomplete type
   99 | const char *ethtool_header_flags_str(enum ethtool_header_flags value)
      |                                      ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
ethtool-user.c: In function ‘ethtool_header_flags_str’:
ethtool-user.c:105:1: warning: control reaches end of non-void function [-Wreturn-type]
  105 | }
      | ^
make[1]: *** [Makefile:40: ethtool-user.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:10: generated] Error 2
In file included from ethtool-user.c:9:
ethtool-user.h:23:43: warning: ‘enum ethtool_header_flags’ declared inside parameter list will not be visible outside of this definition or declaration
   23 | const char *ethtool_header_flags_str(enum ethtool_header_flags value);
      |                                           ^~~~~~~~~~~~~~~~~~~~
ethtool-user.c:99:43: warning: ‘enum ethtool_header_flags’ declared inside parameter list will not be visible outside of this definition or declaration
   99 | const char *ethtool_header_flags_str(enum ethtool_header_flags value)
      |                                           ^~~~~~~~~~~~~~~~~~~~
ethtool-user.c:99:64: error: parameter 1 (‘value’) has incomplete type
   99 | const char *ethtool_header_flags_str(enum ethtool_header_flags value)
      |                                      ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
ethtool-user.c: In function ‘ethtool_header_flags_str’:
ethtool-user.c:105:1: warning: control reaches end of non-void function [-Wreturn-type]
  105 | }
      | ^
make: *** [Makefile:40: ethtool-user.o] Error 1
make: *** Waiting for unfinished jobs....