[Bug] Implicit declaration of function getaddrinfo and freeaddrinfo when compiling

[tuupola]

Describe the bug

With some of the targets compilation fails with two implicit declaration of function errors. For example:

$ make clean
$ make micoair_h743-v2_default -j8
...
<path/to>/PX4-Autopilot/src/modules/uxrce_dds_client/Micro-XRCE-DDS-Client/src/c/profile/transport/ip/udp/udp_transport_posix.c: In function 'uxr_init_udp_platform':
<path/to>/PX4-Autopilot/src/modules/uxrce_dds_client/Micro-XRCE-DDS-Client/src/c/profile/transport/ip/udp/udp_transport_posix.c:46:18: error: implicit declaration of function 'getaddrinfo' [-Wimplicit-function-declaration]
   46 |         if (0 == getaddrinfo(ip, port, &hints, &result))
      |                  ^~~~~~~~~~~
<path/to>/PX4-Autopilot/src/modules/uxrce_dds_client/Micro-XRCE-DDS-Client/src/c/profile/transport/ip/udp/udp_transport_posix.c:57:13: error: implicit declaration of function 'freeaddrinfo' [-Wimplicit-function-declaration]
   57 |             freeaddrinfo(result);
      |             ^~~~~~~~~~~~

Both getaddrinfo() and freeaddrinfo() function require NuttX with NETDB support to be enabled.

include/netdb.h#L286-L296

Which defaults to false.

libs/libc/netdb/Kconfig#L6-L8

I though the problem could be fixed adding CONFIG_LIBC_NETDB=y to nsh/defconfig for the given board. This does not work because the KConfig file does not include prompt for CONFIG_LIBC_NETDB.

Workaround is to enable a feature such as CONFIG_NETDB_HOSTFILE=y which then automatically sets CONFIG_LIBC_NETDB=y and compiling then succeeds.

libs/libc/netdb/Kconfig#L33-L36

Or if you are not using ROS you could just disable the uxrce_dds_client module with:

CONFIG_MODULES_UXRCE_DDS_CLIENT=n

I have two questions.

1. Is nsh/defconfig file the correct place to fix the problem?

2. Should netdb/Kconfig be patched so that directly setting CONFIG_LIBC_NETDB=y via nsh/defconfig would work?

To Reproduce

$ cd PX4-Autopilot
$ make clean
$ make micoair_h743-v2_default -j8

[tuupola]

I was looking at the source code a bit. Since NETDB is required by the uxrce_dds_client correct way would probably be to set CONFIG_NETDB_HOSTFILE=y if CONFIG_MODULES_UXRCE_DDS_CLIENT=y.

I tried to add a select LIBC_NETDB to the module KConfig but that did not have any effect.

[marko-castral]

Im looking forward for resolving this issue properly.

[tuupola]

Ping?

[dakejahl]

are you using a different compiler? I don't have any issues building this target

[tuupola]

$ gcc --version
gcc (GCC) 14.2.1 20240912 (Red Hat 14.2.1-3)

[dakejahl]

I'm still on older gcc

gcc (Ubuntu 11.4.0-1ubuntu1~22.04.2) 11.4.0

[tuupola]

Any news about this?

[marko-castral]

Sadly no, at least as far as i'm concerned.
I was getting this issue on Fedora dev env. I managed to update the code to compile but that was it.
To be fair, when I lost hope in PX4 development on Fedora system (sadly just problem on problem, from px4 core to dependencies) and switched to clean Ubuntu LTS version everything compiled normally again.

[tuupola]

FWIW I just tested a fresh checkout and build still fails with Fedora without PX4/NuttX#351. It succeeds with Ubuntu based distro without patching as @marko-castral mentioned. I am not using Fedora anymore so this is not an issue for me personally anymore.