Re-enable pkg-config tests on windows

[h-vetinari]

Now that conda-forge/openssl-feedstock#106 is in, re-enable pkg-config tests.

I tried adding CMake metadata in conda-forge/libprotobuf-feedstock#128 (to re-enable the CMake tests on unix), but this caused some fall-out. However, CMake has its own custom FindProtobuf function that takes precedence over the packaged CMake metadata; perhaps it's still possible to nudge it to find our protobuf-config-less protobuf)

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[h-vetinari]

Seems this will need some more work on abseil upstream: abseil/abseil-cpp#1276

[h-vetinari]

@traversaro
Any idea how to make CMake's custom FindProtobuf work also on unix? I've tried setting a bunch of variables I see being used in the function, but so far to no avail...

[traversaro]

@traversaro Any idea how to make CMake's custom FindProtobuf work also on unix? I've tried setting a bunch of variables I see being used in the function, but so far to no avail...

The Protobuf CMake package is searched for in https://github.com/grpc/grpc/blob/v1.46.4/cmake/protobuf.cmake#L58 :

find_package(Protobuf REQUIRED ${gRPC_PROTOBUF_PACKAGE_TYPE})

if gRPC_PROTOBUF_PACKAGE_TYPE is CONFIG, then the use of FindProtobuf.cmake is skipped, and the CMake only searches for ProtobufConfig.cmake or protobuf-config.cmake (so-called find_package config mode, see https://cmake.org/cmake/help/v3.24/command/find_package.html#full-signature). So we should avoid that gRPC_PROTOBUF_PACKAGE_TYPE is set to CONFIG. Based on https://github.com/grpc/grpc/blob/v1.46.4/CMakeLists.txt#L89, I guess the other possible value for gRPC_PROTOBUF_PACKAGE_TYPE is MODULE, that even if it is not an option for find_package, at least it is ignored so find_package will go back to the default behaviour of using FindProtobuf.cmake.

TL;DR: pass -DgRPC_PROTOBUF_PACKAGE_TYPE:STRING="MODULE" to CMake config.

[h-vetinari]

Thanks a lot, I'll try this shortly!

[h-vetinari]

Thanks a lot, I'll try this shortly!

No success, unfortunately... 😑