Build errors when including <net/system_client.h>

Golioth Device Help
1

Hi,

I’m trying to get my device connected to the golioth network and am working through a few examples. The issue I am having however is that I can’t compile when I include the Giolioth Zephyr SDK in my project.

Doing this:

#include <net/golioth/system_client.h>

Gives me the following failure:

/home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth/lightdb.h:22:6: error: use of enum 'golioth_content_format' without previous declaration
   22 | enum golioth_content_format;
      |      ^~~~~~~~~~~~~~~~~~~~~~
/home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth/lightdb.h:42:33: error: use of enum 'golioth_content_format' without previous declaration
   42 |                            enum golioth_content_format format,
      |                                 ^~~~~~~~~~~~~~~~~~~~~~
/home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth/lightdb.h:60:30: error: use of enum 'golioth_content_format' without previous declaration
   60 |                         enum golioth_content_format format,
      |                              ^~~~~~~~~~~~~~~~~~~~~~
/home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth/lightdb.h:83:33: error: use of enum 'golioth_content_format' without previous declaration
   83 |                            enum golioth_content_format format,
      |                                 ^~~~~~~~~~~~~~~~~~~~~~
/home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth/lightdb.h:102:30: error: use of enum 'golioth_content_format' without previous declaration
  102 |                         enum golioth_content_format format,
      |                              ^~~~~~~~~~~~~~~~~~~~~~
/home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth/lightdb.h:123:37: error: use of enum 'golioth_content_format' without previous declaration
  123 |                                enum golioth_content_format format,
      |                                     ^~~~~~~~~~~~~~~~~~~~~~
In file included from /home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth.h:13:
/home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth/stream.h:41:33: error: use of enum 'golioth_content_format' without previous declaration
   41 |                            enum golioth_content_format format,
      |                                 ^~~~~~~~~~~~~~~~~~~~~~
/home/cmabon/ncs/v2.5.0-rc1/modules/golioth/include/net/golioth/stream.h:60:30: error: use of enum 'golioth_content_format' without previous declaration
   60 |                         enum golioth_content_format format,

``The project is using the NRF Connect SDK, version 2.5 withe version 0.8 of the Golioth library. The project is being built with C++ but including it through a C file wrapped in Extern “C” didn’t cause any change.

Any help would be greatly appreciated.

2

Hey Camry,

Looks like your compiler can’t find Golioth header files. Can your try the following?

  • build the Golioth hello sample, found at modules/lib/golioth/samples/hello ?
  • make a C project and include the net/golioth/system_client.h header file?
  • change #include <net/golioth/system_client.h> to #include "net/golioth/system_client.h" ?
3

Hi,

Thanks for the quick response. Please see the below.

1 → Building the helo sample went perfect. Used the NRF9160dk build target without issue.
2 → Empty C project also built correctly.
3 → Same issue as before

Hmm, issue here seems to be that I’m working with C++ in Zephyr. Given that it would take a large amount of work to rewrite chunks of the code in C is there any workaround that you guys are aware of here?

4

From the initial comment, I assume you did the following:

#ifdef __cplusplus 
extern "C" {
#endif

// golioth header file content

#ifdef __cplusplus 
}
#endif

in all Golioth header files?

5

Added the extern to all of the Golioth headers and am still getting the same issue when going to build the project.

6

It would seem that in this case, the problem lies in the forward declaration of enums, which you can do in C but not in C++.

Here’s one workaround, by conditionally specifying the size of the enum when using C++ in lightdb.h and stream.h:

struct golioth_client;

enum golioth_content_format
#ifdef __cplusplus
: uint32_t
#endif
;
7

Hi again,

After trying to get it working in C++ I made the call that I was fighting an uphill battle and just took the time to rewrite everything in C.

Really like the product but would really love to see C++ support in the zephyr sdk given zephyrs support for C++!