Reduce compiler warnings

[ofalk]

As discussed in #63 - there are additional warnings that should be addressed:

• -Wstringop-overflow=
• -Wunused-variable
• -Wunused-function

As of 2023-11-06:

# rpmbuild -ba --with check libdnet.spec --quiet 2>&1 | grep -- -W | sed 's/.*\[//; s/\]//' | sort | uniq -c | sort -nr
     34 -Wpointer-sign
      8 -Wincompatible-pointer-types
      2 -Wsizeof-pointer-memaccess
      1 -Wunused-variable
      1 -Wunused-result
      1 -Wunused-function
      1 -Wstringop-overflow=
      1 -Wmaybe-uninitialized
      1 -Wimplicit-function-declaration
      1 -Warray-bounds

[ofalk]

Progress (elimination of unused-*):

# rpmbuild -ta --with check libdnet-1.17.0.tar.gz --quiet 2>&1 | grep -- -W | sed 's/.*\[//; s/\]//' | sort | uniq -c | sort -nr
     34 -Wpointer-sign
      8 -Wincompatible-pointer-types
      2 -Wsizeof-pointer-memaccess
      1 -Wstringop-overflow=
      1 -Wmaybe-uninitialized
      1 -Wimplicit-function-declaration
      1 -Warray-bounds

[kloczek]

New gcc 14.x from fedora rawhide turns -Wincompatible-pointer-types warnings into errors and it trashes building python ext

+ /usr/bin/python3 -sBm build -w --no-isolation
* Getting build dependencies for wheel...
Compiling ./dnet.pyx because it changed.
[1/1] Cythonizing ./dnet.pyx
/usr/lib64/python3.8/site-packages/Cython/Compiler/Main.py:381: FutureWarning: Cython directive 'language_level' not set, using '3str' for now (Py3). This has changed from earlier releases! File: /home/tkloczko/rpmbuild/BUILD/libdnet-libdnet-1.17.0/python/dnet.pxd
  tree = Parsing.p_module(s, pxd, full_module_name)
warning: dnet.pyx:54:0: Global name __iter_append matched from within class scope in contradiction to to Python 'class private name' rules. This may change in a future release.
warning: dnet.pyx:54:0: Global name __iter_append matched from within class scope in contradiction to to Python 'class private name' rules. This may change in a future release.
warning: dnet.pyx:54:0: Global name __iter_append matched from within class scope in contradiction to to Python 'class private name' rules. This may change in a future release.
warning: dnet.pyx:54:0: Global name __iter_append matched from within class scope in contradiction to to Python 'class private name' rules. This may change in a future release.
warning: dnet.pyx:54:0: Global name __iter_append matched from within class scope in contradiction to to Python 'class private name' rules. This may change in a future release.
warning: dnet.pyx:54:0: Global name __iter_append matched from within class scope in contradiction to to Python 'class private name' rules. This may change in a future release.
warning: dnet.pyx:54:0: Global name __iter_append matched from within class scope in contradiction to to Python 'class private name' rules. This may change in a future release.
warning: dnet.pyx:54:0: Global name __iter_append matched from within class scope in contradiction to to Python 'class private name' rules. This may change in a future release.
running egg_info
creating dnet.egg-info
writing dnet.egg-info/PKG-INFO
writing dependency_links to dnet.egg-info/dependency_links.txt
writing top-level names to dnet.egg-info/top_level.txt
writing manifest file 'dnet.egg-info/SOURCES.txt'
dependency ../include/dnet.h won't be automatically included in the manifest: the path can't have `..` segments
ERROR setuptools_scm._file_finders.git listing git files failed - pretending there aren't any
reading manifest file 'dnet.egg-info/SOURCES.txt'
writing manifest file 'dnet.egg-info/SOURCES.txt'
* Building wheel...
running bdist_wheel
running build
running build_ext
building 'dnet' extension
creating build
creating build/temp.linux-x86_64-cpython-38
/usr/bin/gcc -DDYNAMIC_ANNOTATIONS_ENABLED=1 -DNDEBUG -O2 -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fdata-sections -ffunction-sections -flto=auto -flto-partition=none -D_GNU_SOURCE -fPIC -fwrapv -ffat-lto-objects -fno-semantic-interposition -D_GNU_SOURCE -fPIC -fwrapv -O2 -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fdata-sections -ffunction-sections -flto=auto -flto-partition=none -D_GNU_SOURCE -fPIC -fwrapv -ffat-lto-objects -fno-semantic-interposition -O2 -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fdata-sections -ffunction-sections -flto=auto -flto-partition=none -D_GNU_SOURCE -fPIC -fwrapv -ffat-lto-objects -fno-semantic-interposition -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -O2 -g -grecord-gcc-switches -pipe -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -fdata-sections -ffunction-sections -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -flto=auto -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -Wall -Werror=format-security -fPIC -I../include -I/usr/include/python3.8 -c ./dnet.c -o build/temp.linux-x86_64-cpython-38/./dnet.o
./dnet.c: In function ‘__pyx_pf_4dnet_3eth_2get’:
./dnet.c:6158:51: warning: pointer targets in passing argument 1 of ‘PyBytes_FromStringAndSize’ differ in signedness [-Wpointer-sign]
 6158 |   __pyx_t_2 = PyBytes_FromStringAndSize(__pyx_v_ea.data, 6); if (unlikely(!__pyx_t_2)) __PYX_ERR(0, 122, __pyx_L1_error)
      |                                         ~~~~~~~~~~^~~~~
      |                                                   |
      |                                                   uint8_t * {aka unsigned char *}
In file included from /usr/include/python3.8/Python.h:96,
                 from ./dnet.c:50:
/usr/include/python3.8/bytesobject.h:51:50: note: expected ‘const char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
   51 | PyAPI_FUNC(PyObject *) PyBytes_FromStringAndSize(const char *, Py_ssize_t);
      |                                                  ^~~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_3eth_4set’:
./dnet.c:6306:48: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
 6306 |   __pyx_t_1 = __pyx_f_4dnet___memcpy(__pyx_v_ea.data, __pyx_v_value, 6); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 132, __pyx_L1_error)
      |                                      ~~~~~~~~~~^~~~~
      |                                                |
      |                                                uint8_t * {aka unsigned char *}
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_2eth_ntoa’:
./dnet.c:6911:48: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
 6911 |   __pyx_t_1 = __pyx_f_4dnet___memcpy(__pyx_v_ea.data, __pyx_v_buf, 6); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 153, __pyx_L1_error)
      |                                      ~~~~~~~~~~^~~~~
      |                                                |
      |                                                uint8_t * {aka unsigned char *}
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_4eth_aton’:
./dnet.c:7103:51: warning: pointer targets in passing argument 1 of ‘PyBytes_FromStringAndSize’ differ in signedness [-Wpointer-sign]
 7103 |   __pyx_t_3 = PyBytes_FromStringAndSize(__pyx_v_ea.data, 6); if (unlikely(!__pyx_t_3)) __PYX_ERR(0, 162, __pyx_L1_error)
      |                                         ~~~~~~~~~~^~~~~
      |                                                   |
      |                                                   uint8_t * {aka unsigned char *}
/usr/include/python3.8/bytesobject.h:51:50: note: expected ‘const char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
   51 | PyAPI_FUNC(PyObject *) PyBytes_FromStringAndSize(const char *, Py_ssize_t);
      |                                                  ^~~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_6eth_pack_hdr’:
./dnet.c:7330:47: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
 7330 |   __pyx_t_1 = __pyx_f_4dnet___memcpy(__pyx_v_s.data, __pyx_v_src, 6); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 175, __pyx_L1_error)
      |                                      ~~~~~~~~~^~~~~
      |                                               |
      |                                               uint8_t * {aka unsigned char *}
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c:7341:47: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
 7341 |   __pyx_t_1 = __pyx_f_4dnet___memcpy(__pyx_v_d.data, __pyx_v_dst, 6); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 176, __pyx_L1_error)
      |                                      ~~~~~~~~~^~~~~
      |                                               |
      |                                               uint8_t * {aka unsigned char *}
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_12ip_checksum’:
./dnet.c:8437:3: warning: ‘PyObject_AsReadBuffer’ is deprecated [-Wdeprecated-declarations]
 8437 |   __pyx_t_1 = (PyObject_AsReadBuffer(__pyx_v_pkt, (&__pyx_v_p), (&__pyx_v_n)) == 0);
      |   ^~~~~~~~~
In file included from /usr/include/python3.8/Python.h:147:
/usr/include/python3.8/abstract.h:337:17: note: declared here
  337 | PyAPI_FUNC(int) PyObject_AsReadBuffer(PyObject *obj,
      |                 ^~~~~~~~~~~~~~~~~~~~~
./dnet.c:8437:52: error: passing argument 2 of ‘PyObject_AsReadBuffer’ from incompatible pointer type [-Wincompatible-pointer-types]
 8437 |   __pyx_t_1 = (PyObject_AsReadBuffer(__pyx_v_pkt, (&__pyx_v_p), (&__pyx_v_n)) == 0);
      |                                                   ~^~~~~~~~~~~
      |                                                    |
      |                                                    char **
/usr/include/python3.8/abstract.h:338:52: note: expected ‘const void **’ but argument is of type ‘char **’
  338 |                                       const void **buffer,
      |                                       ~~~~~~~~~~~~~^~~~~~
./dnet.c:8437:66: error: passing argument 3 of ‘PyObject_AsReadBuffer’ from incompatible pointer type [-Wincompatible-pointer-types]
 8437 |   __pyx_t_1 = (PyObject_AsReadBuffer(__pyx_v_pkt, (&__pyx_v_p), (&__pyx_v_n)) == 0);
      |                                                                 ~^~~~~~~~~~~
      |                                                                  |
      |                                                                  int *
/usr/include/python3.8/abstract.h:339:51: note: expected ‘Py_ssize_t *’ {aka ‘long int *’} but argument is of type ‘int *’
  339 |                                       Py_ssize_t *buffer_len);
      |                                       ~~~~~~~~~~~~^~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_14ip_cksum_add’:
./dnet.c:8729:3: warning: ‘PyObject_AsReadBuffer’ is deprecated [-Wdeprecated-declarations]
 8729 |   __pyx_t_1 = (PyObject_AsReadBuffer(__pyx_v_buf, (&__pyx_v_p), (&__pyx_v_n)) == 0);
      |   ^~~~~~~~~
/usr/include/python3.8/abstract.h:337:17: note: declared here
  337 | PyAPI_FUNC(int) PyObject_AsReadBuffer(PyObject *obj,
      |                 ^~~~~~~~~~~~~~~~~~~~~
./dnet.c:8729:52: error: passing argument 2 of ‘PyObject_AsReadBuffer’ from incompatible pointer type [-Wincompatible-pointer-types]
 8729 |   __pyx_t_1 = (PyObject_AsReadBuffer(__pyx_v_buf, (&__pyx_v_p), (&__pyx_v_n)) == 0);
      |                                                   ~^~~~~~~~~~~
      |                                                    |
      |                                                    char **
/usr/include/python3.8/abstract.h:338:52: note: expected ‘const void **’ but argument is of type ‘char **’
  338 |                                       const void **buffer,
      |                                       ~~~~~~~~~~~~~^~~~~~
./dnet.c:8729:66: error: passing argument 3 of ‘PyObject_AsReadBuffer’ from incompatible pointer type [-Wincompatible-pointer-types]
 8729 |   __pyx_t_1 = (PyObject_AsReadBuffer(__pyx_v_buf, (&__pyx_v_p), (&__pyx_v_n)) == 0);
      |                                                                 ~^~~~~~~~~~~
      |                                                                  |
      |                                                                  int *
/usr/include/python3.8/abstract.h:339:51: note: expected ‘Py_ssize_t *’ {aka ‘long int *’} but argument is of type ‘int *’
  339 |                                       Py_ssize_t *buffer_len);
      |                                       ~~~~~~~~~~~~^~~~~~~~~~
In file included from ../include/dnet.h:17,
                 from ./dnet.c:1222:
./dnet.c: In function ‘__pyx_pf_4dnet_4addr_3eth___get__’:
../include/dnet/addr.h:35:33: warning: pointer targets in passing argument 1 of ‘PyBytes_FromStringAndSize’ differ in signedness [-Wpointer-sign]
   35 | #define addr_data8      __addr_u.__data8
./dnet.c:10918:61: note: in expansion of macro ‘addr_data8’
10918 |   __pyx_t_3 = PyBytes_FromStringAndSize(__pyx_v_self->_addr.addr_data8, 6); if (unlikely(!__pyx_t_3)) __PYX_ERR(0, 488, __pyx_L1_error)
      |                                                             ^~~~~~~~~~
/usr/include/python3.8/bytesobject.h:51:50: note: expected ‘const char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
   51 | PyAPI_FUNC(PyObject *) PyBytes_FromStringAndSize(const char *, Py_ssize_t);
      |                                                  ^~~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_4addr_3eth_2__set__’:
../include/dnet/addr.h:35:33: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
   35 | #define addr_data8      __addr_u.__data8
./dnet.c:11025:58: note: in expansion of macro ‘addr_data8’
11025 |   __pyx_t_3 = __pyx_f_4dnet___memcpy(__pyx_v_self->_addr.addr_data8, __pyx_v_value, 6); if (unlikely(!__pyx_t_3)) __PYX_ERR(0, 493, __pyx_L1_error)
      |                                                          ^~~~~~~~~~
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_4addr_2ip___get__’:
../include/dnet/addr.h:35:33: warning: pointer targets in passing argument 1 of ‘PyBytes_FromStringAndSize’ differ in signedness [-Wpointer-sign]
   35 | #define addr_data8      __addr_u.__data8
./dnet.c:11157:61: note: in expansion of macro ‘addr_data8’
11157 |   __pyx_t_3 = PyBytes_FromStringAndSize(__pyx_v_self->_addr.addr_data8, 4); if (unlikely(!__pyx_t_3)) __PYX_ERR(0, 502, __pyx_L1_error)
      |                                                             ^~~~~~~~~~
/usr/include/python3.8/bytesobject.h:51:50: note: expected ‘const char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
   51 | PyAPI_FUNC(PyObject *) PyBytes_FromStringAndSize(const char *, Py_ssize_t);
      |                                                  ^~~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_4addr_2ip_2__set__’:
../include/dnet/addr.h:35:33: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
   35 | #define addr_data8      __addr_u.__data8
./dnet.c:11323:60: note: in expansion of macro ‘addr_data8’
11323 |     __pyx_t_4 = __pyx_f_4dnet___memcpy(__pyx_v_self->_addr.addr_data8, __pyx_v_value, 4); if (unlikely(!__pyx_t_4)) __PYX_ERR(0, 513, __pyx_L1_error)
      |                                                            ^~~~~~~~~~
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_4addr_3ip6___get__’:
../include/dnet/addr.h:35:33: warning: pointer targets in passing argument 1 of ‘PyBytes_FromStringAndSize’ differ in signedness [-Wpointer-sign]
   35 | #define addr_data8      __addr_u.__data8
./dnet.c:11457:61: note: in expansion of macro ‘addr_data8’
11457 |   __pyx_t_3 = PyBytes_FromStringAndSize(__pyx_v_self->_addr.addr_data8, 16); if (unlikely(!__pyx_t_3)) __PYX_ERR(0, 522, __pyx_L1_error)
      |                                                             ^~~~~~~~~~
/usr/include/python3.8/bytesobject.h:51:50: note: expected ‘const char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
   51 | PyAPI_FUNC(PyObject *) PyBytes_FromStringAndSize(const char *, Py_ssize_t);
      |                                                  ^~~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_4addr_3ip6_2__set__’:
../include/dnet/addr.h:35:33: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
   35 | #define addr_data8      __addr_u.__data8
./dnet.c:11564:58: note: in expansion of macro ‘addr_data8’
11564 |   __pyx_t_3 = __pyx_f_4dnet___memcpy(__pyx_v_self->_addr.addr_data8, __pyx_v_value, 16); if (unlikely(!__pyx_t_3)) __PYX_ERR(0, 527, __pyx_L1_error)
      |                                                          ^~~~~~~~~~
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_3arp_8loop’:
./dnet.c:15478:64: error: passing argument 2 of ‘arp_loop’ from incompatible pointer type [-Wincompatible-pointer-types]
15478 |   __pyx_t_1 = __Pyx_PyInt_From_int(arp_loop(__pyx_v_self->arp, __pyx_f_4dnet___arp_callback, ((void *)__pyx_v__arg))); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 760, __pyx_L1_error)
      |                                                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                                                |
      |                                                                int (*)(struct arp_entry *, void *)
In file included from ../include/dnet.h:18:
../include/dnet/arp.h:101:43: note: expected ‘arp_handler’ {aka ‘int (*)(const struct arp_entry *, void *)’} but argument is of type ‘int (*)(struct arp_entry *, void *)’
  101 | int      arp_loop(arp_t *arp, arp_handler callback, void *arg);
      |                               ~~~~~~~~~~~~^~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_28arp_pack_hdr_ethip’:
./dnet.c:16141:48: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
16141 |   __pyx_t_1 = __pyx_f_4dnet___memcpy(__pyx_v_sh.data, __pyx_v_sha, 6); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 786, __pyx_L1_error)
      |                                      ~~~~~~~~~~^~~~~
      |                                                |
      |                                                uint8_t * {aka unsigned char *}
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c:16152:48: warning: pointer targets in passing argument 1 of ‘__pyx_f_4dnet___memcpy’ differ in signedness [-Wpointer-sign]
16152 |   __pyx_t_1 = __pyx_f_4dnet___memcpy(__pyx_v_dh.data, __pyx_v_dha, 6); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 787, __pyx_L1_error)
      |                                      ~~~~~~~~~~^~~~~
      |                                                |
      |                                                uint8_t * {aka unsigned char *}
./dnet.c:5576:47: note: expected ‘char *’ but argument is of type ‘uint8_t *’ {aka ‘unsigned char *’}
 5576 | static PyObject *__pyx_f_4dnet___memcpy(char *__pyx_v_dst, PyObject *__pyx_v_src, int __pyx_v_n) {
      |                                         ~~~~~~^~~~~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_4intf_10loop’:
./dnet.c:18820:66: error: passing argument 2 of ‘intf_loop’ from incompatible pointer type [-Wincompatible-pointer-types]
18820 |   __pyx_t_1 = __Pyx_PyInt_From_int(intf_loop(__pyx_v_self->intf, __pyx_f_4dnet___intf_callback, ((void *)__pyx_v__arg))); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 1060, __pyx_L1_error)
      |                                                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                                                  |
      |                                                                  int (*)(struct intf_entry *, void *)
In file included from ../include/dnet.h:25:
../include/dnet/intf.h:64:44: note: expected ‘intf_handler’ {aka ‘int (*)(const struct intf_entry *, void *)’} but argument is of type ‘int (*)(struct intf_entry *, void *)’
   64 | int      intf_loop(intf_t *i, intf_handler callback, void *arg);
      |                               ~~~~~~~~~~~~~^~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_5route_8loop’:
./dnet.c:20336:68: error: passing argument 2 of ‘route_loop’ from incompatible pointer type [-Wincompatible-pointer-types]
20336 |   __pyx_t_1 = __Pyx_PyInt_From_int(route_loop(__pyx_v_self->route, __pyx_f_4dnet___route_callback, ((void *)__pyx_v__arg))); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 1159, __pyx_L1_error)
      |                                                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                                                    |
      |                                                                    int (*)(struct route_entry *, void *)
In file included from ../include/dnet.h:26:
../include/dnet/route.h:34:47: note: expected ‘route_handler’ {aka ‘int (*)(const struct route_entry *, void *)’} but argument is of type ‘int (*)(struct route_entry *, void *)’
   34 | int      route_loop(route_t *r, route_handler callback, void *arg);
      |                                 ~~~~~~~~~~~~~~^~~~~~~~
./dnet.c: In function ‘__pyx_pf_4dnet_2fw_6loop’:
./dnet.c:22262:62: error: passing argument 2 of ‘fw_loop’ from incompatible pointer type [-Wincompatible-pointer-types]
22262 |   __pyx_t_1 = __Pyx_PyInt_From_int(fw_loop(__pyx_v_self->fw, __pyx_f_4dnet___fw_callback, ((void *)__pyx_v__arg))); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 1295, __pyx_L1_error)
      |                                                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                                              |
      |                                                              int (*)(struct fw_rule *, void *)
In file included from ../include/dnet.h:27:
../include/dnet/fw.h:50:38: note: expected ‘fw_handler’ {aka ‘int (*)(const struct fw_rule *, void *)’} but argument is of type ‘int (*)(struct fw_rule *, void *)’
   50 | int      fw_loop(fw_t *f, fw_handler callback, void *arg);
      |                           ~~~~~~~~~~~^~~~~~~~
error: command '/usr/bin/gcc' failed with exit code 1

[ofalk]

I can confirm this observation - it's going to require a lot of type casting, but since the code is generated from Cython, this is going to be a bit more difficult. :-( If there is anyone out there who has experience and can look into it, it would be appreciated!

[ofalk]

BTW. I think we should spin this off into a separate issue.

[NHOrus]

Causes Gentoo bug https://bugs.gentoo.org/933360
Good luck!

[ofalk]

Causes Gentoo bug https://bugs.gentoo.org/933360 Good luck!

Fixed with #104 - thanks to @clan