[AVRO-3967] Replace boost::format with fmt library

[mkmkme]

AVRO-3967

This reduces the binary size quite significantly and doesn't require an additional object creation during exception throwing.

What is the purpose of the change

This change replaces boost::format with fmt library. It increases the readability and reduces the binary size quite significantly (on my machine I noticed avrogencpp being 27M with boost::format and 14M with fmt.

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Documentation

• Does this pull request introduce a new feature? no

[martin-g]

This change is a trivial rework

It might be trivial to you but to me it looks like it needs a JIRA issue (for the changelog) :-)

[mkmkme]

Sure! Sorry I hadn't added it earlier. Will do this now

[mkmkme]

I see that fmt::fmt-header-only was not found on ARM Linux. Will try to see what version of fmt is being installed on the host.

In general, I would like to see it updated at some pointed as it seems quite a bit outdated tbh

[martin-g]

The ARM64 builders run on Ubuntu 20.04 with GCC 9.3.0

[mkmkme]

@martin-g so the quick research shows that on Ubuntu 20.04 the version of fmt is too old (6.1.2 while the latest one is 10.2.0).

As an alternative of relying to the system dependencies we can use FetchContent in order to download fmt during the configuration step. The downside of this is that we'll have to build fmt as part of building avro-cpp (although the library is very small and doesn't have dependencies on its own).
The upside of that is that we won't be relying on the system package libfmt-dev and developers wouldn't need to install it themselves.

WDYT?

[martin-g]

The ARM64 CI is a nice to have so we can ignore it! But it will fail again for any following C++ PR too!
I've asked Apache Infra about upgrading the ARM64 CI runners to a newer Ubuntu but it might take some time...
Yet another option is to use some PPA to install newer libfmt-dev in the ARM64 CI job.

[mkmkme]

Thanks for the help! Let's hear from Apache Infra...

I'll try to find PPA for fmtlib, but it seems it's not that common, especially for ARM64.

[martin-g]

https://ubuntu.pkgs.org/22.04/ubuntu-universe-arm64/libfmt-dev_8.1.1+ds1-2_arm64.deb.html
it depends on https://ubuntu.pkgs.org/22.04/ubuntu-universe-arm64/libfmt8_8.1.1+ds1-2_arm64.deb.html

apt install http://ports.ubuntu.com/pool/universe/f/fmtlib/libfmt8_8.1.1+ds1-2_arm64.deb
apt install http://ports.ubuntu.com/pool/universe/f/fmtlib/libfmt-dev_8.1.1+ds1-2_arm64.deb

[mkmkme]

Thanks! Let's see if fmt 8 will do the trick

[mkmkme]

Checked locally with Ubuntu 20.04 docker image, and it doesn't work unfortunately :(

The following packages have unmet dependencies:
 libfmt8 : Depends: libc6 (>= 2.33) but 2.31-0ubuntu9.14 is to be installed
           Depends: libstdc++6 (>= 11) but 10.5.0-1ubuntu1~20.04 is to be installed
E: Unable to correct problems, you have held broken packages.

Alternatively, I can try to build it just on that Ubuntu in CI. Shouldn't take long.

[mkmkme]

Could you trigger the CI before I fix the merge conflicts? Wanna see if taking the latest one with FetchContent would do the trick.

[martin-g]

I can't! You need to resolve the conflicts first

[mkmkme]

Hey, I've pushed one more commit. Could this be approved to trigger the CI?

[martin-g]

Is this include needed/used ?

[mkmkme]

Sorry I currently have a limited access to my laptop (until Friday). I'll double check this by next week.
IIRC I got compile error without it because I removed include of boost/format from one of the headers. But I'll definitely double check

[mkmkme]

@martin-g so yeah this include is needed, because there's usage of std::vector in the signature of snapshot() on line 177. Without it, compilation failed for me.

[martin-g]

Thank you, @mkmkme !

[marlowa]

The fmt library was added to cpp in cpp20. So this change would break projects on an older dialect, such as cpp17.

[florianhumblot]

The fmt library was added to cpp in cpp20. So this change would break projects on an older dialect, such as cpp17.

@marlowa libfmt is not the same as std::fmt, the https://github.com/fmtlib/fmt project is compatible with older c++ standards than c++20 where <format> and std::fmt were introduced :)