qtprotobuf/cmake/ProtobufLookup.cmake

if(NOT Protobuf_FOUND)
    find_package(Protobuf CONFIG)
    if(NOT Protobuf_FOUND)
        if(CMAKE_SIZEOF_VOID_P EQUAL 8)
            set(FIND_LIBRARY_USE_LIB64_PATHS TRUE)
            set(FIND_LIBRARY_USE_LIBX32_PATHS FALSE)
            set(FIND_LIBRARY_USE_LIB32_PATHS FALSE)
        else()
            set(FIND_LIBRARY_USE_LIBX32_PATHS TRUE)
            set(FIND_LIBRARY_USE_LIB32_PATHS TRUE)
            set(FIND_LIBRARY_USE_LIB64_PATHS FALSE)
        endif()

        find_library(Protobuf_LIBRARY protobuf)
        if(NOT Protobuf_LIBRARY STREQUAL PROTOBUF_LIBRARY-NOTFOUND)
            add_library(protobuf::libprotobuf SHARED IMPORTED)
            set_target_properties(protobuf::libprotobuf PROPERTIES IMPORTED_LOCATION ${Protobuf_LIBRARY})
        endif()

        find_program(Protobuf_PROTOC_EXECUTABLE protoc)
        if(NOT Protobuf_PROTOC_EXECUTABLE STREQUAL Protobuf_PROTOC_EXECUTABLE-NOTFOUND)
            add_executable(protobuf::protoc IMPORTED)
            set_target_properties(protobuf::protoc PROPERTIES IMPORTED_LOCATION ${Protobuf_PROTOC_EXECUTABLE})
        endif()

        find_package(Threads)
        find_library(Protobuf_PROTOC_LIBRARY protoc)
        if(NOT Protobuf_PROTOC_LIBRARY STREQUAL PROTOBUF_PROTOC_LIBRARY-NOTFOUND)
            add_library(protobuf::libprotoc SHARED IMPORTED)
            set_target_properties(protobuf::libprotoc PROPERTIES IMPORTED_LOCATION ${Protobuf_PROTOC_LIBRARY}
                INTERFACE_LINK_LIBRARIES Threads::Threads)
        endif()

        unset(Protobuf_FOUND)
        if(NOT Protobuf_LIBRARY STREQUAL Protobuf_LIBRARY-NOTFOUND
                AND NOT Protobuf_PROTOC_EXECUTABLE STREQUAL Protobuf_PROTOC_EXECUTABLE-NOTFOUND
                AND NOT Protobuf_PROTOC_LIBRARY STREQUAL Protobuf_PROTOC_LIBRARY-NOTFOUND)
            set(Protobuf_FOUND TRUE)
            message(STATUS "Found protobuf installation: ${Protobuf_PROTOC_EXECUTABLE} ${Protobuf_PROTOC_LIBRARY} ${Protobuf_LIBRARY}")
        else()
            message(FATAL_ERROR "Protobuf is a hard dependency of the project. You may install it (with gRPC) by following instructions in cmake/gRPCBuild.cmake script.")
            unset(Protobuf_LIBRARY)
            unset(Protobuf_PROTOC_EXECUTABLE)
            unset(Protobuf_PROTOC_LIBRARY)
        endif()
    endif()
endif()