I was able to reproduce the gssapi & openssl error on windows. I tried
on PG16 with msvc build system and on PG17 with meson build system.
The error was reproducible when enabling both openssl and gssapi from
the configurations. Turns out that it was due to the conflicting
macros.
"be-secure-openssl.c" tries to prevent this conflict here [1]. But the
error again appears when gssapi is enabled. The file
"be-secure-openssl.c" fails to compile because it has a similar
scenario as explained here [2]. The header libpq.h is indirectly
including libpq-be.h which has a wrong order of including openssl
headers. Header "gssapi.h" indirectly includes "wincrypt.h" and
openssl header should be defined after gssapi includes.
Now this can either be solved by just just undefine the macro defined
by wincrypt.h as done here [3]
```
#ifdef X509_NAME
#undef X509_NAME
#endif
```
Or we should rearrange our headers. Openssl header should be at the
bottom (after the gssapi includes).
I am attaching the patch here in which I rearranged the openssl header
in libpq-be.h
[1]:
https://github.com/postgres/postgres/blob/8ba34c698d19450ccae9a5aea59a6d0bc8b75c0e/src/backend/libpq/be-secure-openssl.c#L46
[2]: https://github.com/openssl/openssl/issues/10307#issuecomment-964155382
[3]: https://github.com/postgres/postgres/blob/00ac25a3c365004821e819653c3307acd3294818/contrib/sslinfo/sslinfo.c#L29
Thanks
Imran Zaheer
Bitnine
