got it, i will resolve all these warnings. One wired thing when i set up CI is the docker image seems having a postgres version which conflicts with my test version. So, CI is broken now ,although tests pass at my local box. I will also figure this out.
> The repo currently can be build on my mac. You can check it out. > Also I am working on the CI config to monitor each commit.
Tests pass on Arch Linux with PostgreSQL 11 and Ubuntu 16.04 with PostgreSQL 9.6. However there is a name conflict in case of PostgreSQL 11: https://afiskon.ru/s/7a/fe681b17f0_paste.txt I suggest to rename the procedure to `convert_int8_to_char`.
Also GCC still generates a lot of warnings (see my previous message). I would advise to fix all these warnings, otherwise you can miss a really important warning. Ideally, the code should be compiled with -Wall flag.
