Use new carla-native-plugin library

[falkTX]

Also fixes build with latest carla (which will be 2.0 soon)

Should be pushed to stable-1.2 branch too, but there will be conflicts to resolve for that.
@tresf can I let you handle that?

[PhysSong]

stable-1.1 is no longer used, so you should open a PR against stable-1.2.
I think @tresf can handle conflicts. If not, I can help you resolve them.

[falkTX]

stable-1.1 is still the latest stable release of LMMS available, and it is simply not true that is no longer used - I am using it myself and everyone with kxstudio repos.
Without the patch, the build fails against latest carla.
This is a bugfix, not a new feature. Please merge.

[PhysSong]

BTW, won't it make the build fail with old version of Carla?

[falkTX]

no, as the library it uses was changed. it no longer links against the full carla standalone lib, but only against the exported plugin version (libcarla_native-plugin.so).
it makes a lot more sense to link against this new object file.

as it is now, stable-1.1 finds carla-standalone and then fails to build.
the patch fixes this, among other things.

[PhysSong]

I meant there's no fallback logic for old versions. It looks like a regression to me. Can we try carla-standalone if the old version of Carla is detected?

stable-1.1 finds carla-standalone and then fails to build.

I can't reproduce it. Do you have a build log with the failure?

[falkTX]

treat it as a regression if you wish, I feel like now it is doing things proper.
the symbols it uses are all defined in a single header file, which is the one also used when exporting the library.
the old behaviour was hacky, experimenting with getting it to work.
now with carla going stable (2.0), it was time to clear up the hacks and make things work properly.

I dont have the logs with the failure, but the error only happens due to -Werror.
You need latest git of carla (from maximum 2 days ago) to get the new header file and library.

[tresf]

I have mixed feelings about this landing on the stable-1.1 branch. First of all, I really don't care because the branch is stale, unmaintained and doesn't provide any binaries to our website, so the impact is only downstream and I can't speak on behalf of downstream + Carla. @falkTX perhaps you can shed some insight on this?

So the impact of merging this to stable-1.1 is:

• This would only impact distros that ship 1.1 (which most do) that would pull from HEAD of the stable-1.1 branch. Does this ever happen? I can't imagine this would be common, instead they'd pull from the 1.1.3 release. Do we need to ship a 1.1.4 version? It would be for Carla only -- specifically Linux Carla -- as the Windows and Mac builds are not impacted by this change.
• What I don't truly understand is how the distros get Carla to begin with. I'm familiar with the Debian/Ubuntu technique but even then I'm not exactly sure how it's provided as I don't think the major distributions have Carla support baked in. If this is only to satisfy the KXStudio's build process, then it seems like a sane change.
• @PhysSong's concerns about regression handling seem valid but only if the distribution of these libraries happens separately and I can't speak on behalf of those distros. The ones that come to mind are Fedora and Arch, which we get a lot of bug reports for -- including Carla bug reports but just to put our bug reports into perspective... (Build failure when linking carlabase.so: undefined references  #4156, Carla not detected on openSUSE with lmms-1.2.0-rc6-linux-x86_64.AppImage #4515, Loading certain instruments in Carla Rack causes a segfault #3452, Carla and libgig not found by cmake though I have installed them #3218, Effect in carla-rack are not exported #2213, When exporting a song with carla-jack, sample rates are not set correctly #2212, Since commit bc77a13, carla plugin doesn't compile anymore #2549, Missing Carla files? #2543, maybe carla error #1444, Carla locale issue #1221, Carla loses plugins #1201, Lmms/Carla problem on linux ubuntu [latest stable build] #1199).

What I think would be more responsible of a change -- albeit leaving cruft into the Carla build system -- is for @falkTX to leave the old library around and deprecate it off sanely instead of putting this decision on us at LMMS. The justification for this is we've worked with package maintainers that require a version bump to receive a change so I'd like to be cognizant of that. Otherwise, they'd potentially get the new Carla and the old LMMS and then it would break.

So a single, small commit to 1.1.3 to provide compatibility with the latest Carla seems rather benign but I want to know how this can impact other distros and that's something I simply don't know. Bumping 1.1.3 to 1.1.4 for this is possible as well so as long a package maintainers are careful to update LMMS and Carla simultaneously (which I wouldn't expect them to know to do).

@falkTX thoughts welcome. :)

Edit: And I just remembered that PKG_CHECK_MODULES(CARLA carla-native-plugin) is going to make sure the build system is prepared, so the worst that will happen is Carla will just be missing from LMMS downstream if the versions aren't matched up.

[falkTX]

thanks for the reply.

I understand the situation, I was hoping 1.1 would still be maintained in a way.
it is the current stable branch, and the one I am still using. but it is fine that it is not supported anymore.
In such cases, then I really recommend taking out -Werror, and that is it.
Without that flag, carla will keep building and working just fine with the current code.

Most distros don't have Carla afaik.
I know Arch does, I know the maintainer for the packager and we meet in Berlin from time to time, so I can request updates in person :P
Some Fedora and Gentoo audio overlay/repos/external-sources contain it too, but I dont know how those work.
Debian does not have it, neither does Ubuntu.

@tresf could you please merge this patch into your lmms-carla-osx PR?
I think pushing to 1.2 branch right now is a bit pointless, if you will have conflicts with it right away, so you will have to resolve them anyway.

[tresf]

@tresf could you please merge this patch into your lmms-carla-osx PR?
I think pushing to 1.2 branch right now is a bit pointless, if you will have conflicts with it right away, so you will have to resolve them anyway.

Yes, I'll make it part of the stable-1.2 macOS Carla PR (#4558)