Please include Protobuf into conan-center

[Croydon]

In order to move the creation of a gRPC recipe further, it would be really helpful to have Protobuf in conan-center. Please consider making an inclusion request for Protobuf.

Furthermore there seems to quite some demand for it anyway 😄

https://croydon.github.io/conan_inquiry/#!stats

Packages available in many remotes but not in conan-center
Protobuf has 7 remotes

[SSE4]

/cc @zamazan4ik

[SSE4]

@uilianries are we done with it? :)

[uilianries]

Yes! We could request for the inclusion on Conan center 😄

[Croydon]

Please go ahead then :)

[uilianries]

I just requested the inclusion 3 days ago 😄

[SSE4]

NOTE: protoc_installer couldn't be just build_require, it will be usual require, since all packages dependent on protobuf will need protoc, not just protobuf itself

[SSE4]

status update:
protoc_installer and protobuf are working good with cross-compilation on 3.6.1 branch.
now I'll take my time to backport changes into 3.5.1/3.5.2 branches, and we're ready for conan-center inclusion I believe.

[SSE4]

@danimtb I think we're ready to go. I've backported changes to 3.5.2 branch, and 3.6.1 is also done. I don't think we need 3.5.1 if we have 3.5.2 (I don't see the point into supporting two minor releases). so, please take a look.

[Croydon]

@danimtb Any news? 😄

[uilianries]

I updated both conan-protobuf and conan-protoc_installer

https://github.com/bincrafters/conan-protobuf/pulls
https://github.com/bincrafters/conan-protoc_installer/pulls

[uilianries]

Hi @danimtb !

All branches were updated! including protoc_installer. Could you review, please?

https://github.com/bincrafters/conan-protoc_installer/tree/stable/3.6.1
https://github.com/bincrafters/conan-protoc_installer/tree/stable/3.5.2
https://github.com/bincrafters/conan-protoc_installer/tree/stable/3.5.1

https://github.com/bincrafters/conan-protobuf/tree/stable/3.6.1
https://github.com/bincrafters/conan-protobuf/tree/stable/3.5.2
https://github.com/bincrafters/conan-protobuf/tree/stable/3.5.1

Regards!

[danimtb]

Hi!

Update: We are currently discussing the dependency relationship among protobuf, protoc and consumers of protobuf library. We are making some progress to have it included in Conan Center but will still require some work.

Thanks @uilianries for updating the recipes.

[elizagamedev]

Currently the protobuf recipe exposes all of libprotobuf, libprotobuf-lite, and libprotoc to consumers. As I've discovered, linking to both libprotobuf and libprotobuf-lite will result in undefined behavior. Additionally, linking to libprotoc is not a common use case. To resolve these problems, would this design be acceptable?

• A new boolean option lite which defaults to False and appends either libprotobuf or libprotobuf-lite depending on its value to cpp_info.libs
• A new boolean option libprotoc which defaults to False and, if true, appends libprotoc to cpp_info.libs

[uilianries]

/cc @jgsogo

[jgsogo]

Hi!

I think that this should be the dependency graph associated with these packages (meaning of arrows is requires/depends on):

As @elizagamedev says, we cannot link both with libprotobuf and libprotobuf-lite. Talking about CMake, consumer can use targets and link against CONAN_PCK::libprotobuf or CONAN_PCK::libprotobuf-lite, but using the direct approach with ${CONAN_LIBS}, we should have a way to select which one to link (and yes, by default I would use the no-lite one). About libprotoc, as it is contained in another package (I think it will usually be a build_requires) it won't be exposed in ${CONAN_LIBS}

[uilianries]

Hi @jgsogo, thanks for you help! 😸

So we could create two packages as well, but protoc_installer will depend on protobuf, if I get it.

Also, we will need to add an option for protobuf-lite and exclude libprotobuf from CONAN_LIBS, but if on same build the customer requires protoc and protobuf there will be a problem.

Will we need to create a new package for libprotobuf-lite only? 🤔

As libprotoc is only required by protoc, we could use static link.

[jgsogo]

Yes, protoc_installer depends on protobuf (it happens the other way around (not binary dep, just workflow) if we were to compile tests, as most of the tests for the protobuf package requires protoc binary to generate code based on .proto files, but we are not building nor running tests).

protobuf package must allow the consumer to choose between linking with libprotobuf or libprotobuf-lite (usually the first one, I think, but I've always developed for systems plenty of resources).

If the consumer just want protoc to generate code, it will be ok to link statically, but someone may want to link against libprotoc in order to make his own protobuf generator (who knows...).

So the problem will be if the consumer requires both of them. We will have a diamond and we will transitively link to libprotobuf, so there will be a conflict if we want to link to the -lite version too. I've always considered ${CONAN_LIBS} a shorthand, user can select which libraries to link.

---

One more issue we could have with this library is how to deploy the CMake macros protobuf_generate_cpp, how the consumer will include them. These usually are included through the find_package(Protobuf) because they are defined inside the FindProtobuf.cmake file, where are they when requiring protoc_installer?

[sourcedelica]

Agreed that protoc_installer needs a CMake macro to generate C++ and Python code. Ideally it would work with find_package(Protobuf), or at least the macros would be named protobuf_generate_cpp and protobuf_generate_python and would work the same way as the macros of the same names from FindProtobuf.

[Croydon]

Blocked by #598 & #604

[SSE4]

Now in conan center

[Croydon]

There are still several huge issues, aren't there? Why was it added to conan-center now?

[uilianries]

Most simple cases are working and protobuf is very popular. We can continue fixing and updating.

[SSE4]

okay, as we have other issues to track, can we close this one?

[danimtb]

I think this can be closed as the packages are already in Conan Center