Updating libpqxx to 8.0.1

Hi All,

There is a new major version (8.x) of libpqxx available and I have spent
a bit of time over the past couple of days looking at what would be
involved in updating the Debian package to this new version. Below you
will find a summary of my findings and some initial work that I have
done to prepare for packaging the new version of libpqxx. I don't think
it makes sense to update the package just yet since a couple of reverse
dependencies need to be updated upstream and in Debian in order to
support building and linking against libpxx 8.x. I wanted to share my
findings here and ask if there is anything that I have overlooked in my
investigation.

Many thanks
--
Bradford

* libpqxx has released a new major version
* 8.0.0 was released 2026-02-23
* 8.0.1 was released 2026-04-04
* Requires compiling with at least C++20
* Updating the Debian packaging appears to be straightforward; I have
updated the packaging locally and successfully built with sbuild.

Using build-rdeps, I have identified four packages that depend on
libpqxx-dev. They are:

* quickfix
* libpqxx-dev is listed as a Build-Depends but it appears to be unused
(currently nor historically)
* Should _probably_ build-depend on libpq-dev if PostgreSQL
functionality is wanted
* #1136714 - quickfix: remove build dependency on libpqxx-dev
* hipercontracer
* Already supports building against libpqxx 8+
* Still sets C++17 for Debian builds
* Minor change in CMakeLists.txt to conditionally set C++20 based on
the detected version
* https://github.com/dreibh/hipercontracer/pull/4
* osm2pgrouting
* Minor change in CMakeLists.txt to conditionally set C++20 based on
the detected version
* https://github.com/pgRouting/osm2pgrouting/pull/328
* sqlsmith
* Requires the most extensive set of changes to support compiling
against libpqxx 8+
* Submitted an initial PR to upstream
* https://github.com/anse1/sqlsmith/pull/63

None of the rdeps have reverse dependencies themselves.

* GCC 15 defaults to C++17
* Default form 11 to 15
* C++20 was not stable until GCC 16
* The documentation for C++ Standards Support in GCC indicates that
most/several C++20 features are supported in GCC 11+
* Debian bookworm gcc 12
* Debian trixie gcc 14
* Ubuntu jammy gcc 11
* Ubuntu noble gcc 13