Undefined reference when building PQXX (pqxx::internal::clear_result(pg_result const*)

[Luis-Abreu]

Hi everyone,
I'm having problems testing the library, I'm getting the following error:

test_escape.o: In function `pqxx::internal::PQAlloc<pg_result const, &pqxx::internal::clear_result>::loseref()':
/libpqxx-master/test/unit/../../include/pqxx/util.hxx:609: undefined reference to `pqxx::internal::clear_result(pg_result const*)'

What I did to build the library was:
./configure --prefix=/usr/local --enable-shared
make -j8
sudo make install

[jtv]

Looks like there could be a version mismatch... as of a few days ago, PQAlloc no longer exists. Is it possible that you've got an older version of the headers installed, so that the build is picking up those instead of the new ones from the version that you're trying to build?

[scottfurry]

Apologies for resurrecting this thread, but it seems rather pertinent to my current situation.
I'm updating code that uses libpqxx but linking fails.
libpq ver 9.6.5 build date 2017Sep06
libpqxx ver 5.1.0 build date 2017Aug03

I don't see the "PQAlloc" notice, but I receive numerous linking errors stating "undefined reference to `pqxx::internal::clear_result(pg_result const*)'". Can you clarify, please.

[jtv]

Ah, this may be that problem where I forgot to export clear_result! It's fixed in 6.0, but obviously that won't help 5.1.

In include/pqxx/result.hxx, try prefixing the clear_result declaration with PQXX_LIBEXPORT. So it becomes:
PQXX_LIBEXPORT void clear_result(const pq::PGresult *);

I believe this problem shows up only when linking dynamically against libpqxx. It may be safer to link statically — it's just so easy to sneak in a binary-incompatible change in C++!

[scottfurry]

I had already tried changing the line in include/pqxx/result.hxx without success.
This lead to creating issue #33.

[jtv]

Hopefully the newly pushed 5.1 branch and updated 5.1.1 tag will solve this...

[scottfurry]

Yes - version bump solved the problem is it caught the change.