missing protoc tool in protobuf package

[mahaase]

basement-gnu-linux/recipes/libs/protobuf.yaml

Line 34 in d49a7b1

buildTools: [protoc]

IMO we should add

depends:
  - name: libs::protobuf
    use: [tools]
    tools:
      target-toolchain: host-compat-toolchain

for -dev and -tgt target. currently the user of the packages must do it.

[mahaase]

and how should this be used.

i needed a helper like this:

inherit: [buildenv]

buildTools: [protoc]
buildSetup: |
    cat >protoc-tool.cmake <<EOF
    if(NOT TARGET protobuf::protoc)
        add_executable(protobuf::protoc IMPORTED GLOBAL)
        set_property(TARGET protobuf::protoc PROPERTY
            IMPORTED_LOCATION "${BOB_TOOL_PATHS[protoc]}/protoc")
    endif()
    EOF

    PROTOC_CMAKE_FLAGS=( "-DCMAKE_PROJECT_TOP_LEVEL_INCLUDES=${PWD}/protoc-tool.cmake" )

    buildenvBuildProtobuf()
    {
        buildenvBuildAll "${PROTOC_CMAKE_FLAGS[@]}" "$@"
    }

protobuf needs a cmake target called protobuf::protoc. but this is not exported. so i get the error, that the tool protobuf::protoc isn't a command...

[jkloetzke]

Not sure. Maybe @rhubert can shed some light on this?

buildenv is not an upstream class. Is your last comment about how to use protobuf with some internal module on your side or in general?

[rhubert]

For the first question: protoc is usually a required buildTool for the package that depends on protobuf-dev as well. So add a forward tool dependency somewhere above this to have the same tool available for both.

I don't understand the second issue. Maybe it's just required if protoc is used from a cmake build? We do not have this combination...

[mahaase]

For the first question: protoc is usually a required buildTool for the package that depends on protobuf-dev as well. So add a forward tool dependency somewhere above this to have the same tool available for both.

so would it make sense to add:

depends:
  - name: libs::protobuf
    use: [tools]
    tools:
      target-toolchain: host-compat-toolchain

currently, if the user just depends on:

    - libs::protobuf-dev

    - use: []
      depends:
          - libs::protobuf-tgt

will get the error about missing tool protoc. this could be fixed by the first block and is used in some different packages already?!

I don't understand the second issue. Maybe it's just required if protoc is used from a cmake build? We do not have this combination...

yes the issue is about using protoc in a package. we use a function called protobuf_generate of protobuf-generate.cmake. via

if(NOT protobuf_generate_PROTOC_EXE)
  # Default to using the CMake executable
  set(protobuf_generate_PROTOC_EXE protobuf::protoc)
endif()

protobuf gets the protoc tool. it shall be a cmake target called. like we can see, it is possible to override via -D cmake variables.

so my fix now is like this:

buildTools: [protoc]
buildSetup: |
    PROTOC_CMAKE_FLAGS=( "-Dprotobuf_generate_PROTOC_EXE=${BOB_TOOL_PATHS[protoc]}/protoc" )

    buildProtobuf()
    {
        cmakeBuild "${PROTOC_CMAKE_FLAGS[@]}" "$@"
    }

buildenv is not an upstream class.

is just a cmake class wrapper on our side.

[rhubert]

For the first question: protoc is usually a required buildTool for the package that depends on protobuf-dev as well. So add a forward tool dependency somewhere above this to have the same tool available for both.

so would it make sense to add:

depends:
  - name: libs::protobuf
    use: [tools]
    tools:
      target-toolchain: host-compat-toolchain

We have exactly this in the tests/buildall recipe. It shouldn't hurt to add it to the recipe and maybe - if the generated files are part of the repository - would even work in some cases without the need of the additional tool dependency...

cmake issue: I guess this is because the cmake files are part of the (cross-compiled) dev package which did not contain the (host)-protoc-tool referenced by these files somehow. You might be able to workaround this by patching the cmake files of the dev package to use the BOB_TOOLS_PATH['protobuf'] instead.