llvm/cmake/modules/FindGRPC.cmake

# This setup requires gRPC to be built from sources using CMake and installed to
# ${GRPC_INSTALL_PATH} via -DCMAKE_INSTALL_PREFIX=${GRPC_INSTALL_PATH}.
# FIXME(kirillbobyrev): Check if gRPC and Protobuf headers can be included at
# configure time.
if (GRPC_INSTALL_PATH)
  set(protobuf_MODULE_COMPATIBLE TRUE)
  find_package(Protobuf CONFIG REQUIRED HINTS ${GRPC_INSTALL_PATH})
  message(STATUS "Using protobuf ${protobuf_VERSION}")
  find_package(gRPC CONFIG REQUIRED HINTS ${GRPC_INSTALL_PATH})
  message(STATUS "Using gRPC ${gRPC_VERSION}")

  include_directories(${Protobuf_INCLUDE_DIRS})

  # gRPC CMake CONFIG gives the libraries slightly odd names, make them match
  # the conventional system-installed names.
  set_target_properties(protobuf::libprotobuf PROPERTIES IMPORTED_GLOBAL TRUE)
  add_library(protobuf ALIAS protobuf::libprotobuf)
  set_target_properties(gRPC::grpc++ PROPERTIES IMPORTED_GLOBAL TRUE)
  add_library(grpc++ ALIAS gRPC::grpc++)

  set(GRPC_CPP_PLUGIN $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
  set(PROTOC ${Protobuf_PROTOC_EXECUTABLE})
else()
  find_program(GRPC_CPP_PLUGIN grpc_cpp_plugin)
  find_program(PROTOC protoc)
  if (GRPC_CPP_PLUGIN-NOTFOUND OR PROTOC-NOTFOUND)
    message(FATAL_ERROR "gRPC C++ Plugin and Protoc must be on $PATH for Clangd remote index build")
  endif()
  # On macOS the libraries are typically installed via Homebrew and are not on
  # the system path.
  if (${APPLE})
    find_program(HOMEBREW brew)
    # If Homebrew is not found, the user might have installed libraries
    # manually. Fall back to the system path.
    if (NOT HOMEBREW-NOTFOUND)
      execute_process(COMMAND ${HOMEBREW} --prefix grpc
        OUTPUT_VARIABLE GRPC_HOMEBREW_PATH
        RESULT_VARIABLE GRPC_HOMEBREW_RETURN_CODE
        OUTPUT_STRIP_TRAILING_WHITESPACE)
      execute_process(COMMAND ${HOMEBREW} --prefix protobuf
        OUTPUT_VARIABLE PROTOBUF_HOMEBREW_PATH
        RESULT_VARIABLE PROTOBUF_HOMEBREW_RETURN_CODE
        OUTPUT_STRIP_TRAILING_WHITESPACE)
      # If either library is not installed via Homebrew, fall back to the
      # system path.
      if (GRPC_HOMEBREW_RETURN_CODE EQUAL "0")
        include_directories(${GRPC_HOMEBREW_PATH}/include)
        link_directories(${GRPC_HOMEBREW_PATH}/lib)
      endif()
      if (PROTOBUF_HOMEBREW_RETURN_CODE EQUAL "0")
        include_directories(${PROTOBUF_HOMEBREW_PATH}/include)
        link_directories(${PROTOBUF_HOMEBREW_PATH}/lib)
      endif()
    endif()
  endif()
endif()

# Proto headers are generated in ${CMAKE_CURRENT_BINARY_DIR}.
# Libraries that use these headers should adjust the include path.
# FIXME(kirillbobyrev): Allow optional generation of gRPC code and give callers
# control over it via additional parameters.
function(generate_grpc_protos LibraryName ProtoFile)
  get_filename_component(ProtoSourceAbsolutePath "${CMAKE_CURRENT_SOURCE_DIR}/${ProtoFile}" ABSOLUTE)
  get_filename_component(ProtoSourcePath ${ProtoSourceAbsolutePath} PATH)

  set(GeneratedProtoSource "${CMAKE_CURRENT_BINARY_DIR}/Index.pb.cc")
  set(GeneratedProtoHeader "${CMAKE_CURRENT_BINARY_DIR}/Index.pb.h")
  set(GeneratedGRPCSource "${CMAKE_CURRENT_BINARY_DIR}/Index.grpc.pb.cc")
  set(GeneratedGRPCHeader "${CMAKE_CURRENT_BINARY_DIR}/Index.grpc.pb.h")
  add_custom_command(
        OUTPUT "${GeneratedProtoSource}" "${GeneratedProtoHeader}" "${GeneratedGRPCSource}" "${GeneratedGRPCHeader}"
        COMMAND ${PROTOC}
        ARGS --grpc_out="${CMAKE_CURRENT_BINARY_DIR}"
          --cpp_out="${CMAKE_CURRENT_BINARY_DIR}"
          --proto_path="${ProtoSourcePath}"
          --plugin=protoc-gen-grpc="${GRPC_CPP_PLUGIN}"
          "${ProtoSourceAbsolutePath}"
          DEPENDS "${ProtoSourceAbsolutePath}")

  add_clang_library(${LibraryName} ${GeneratedProtoSource} ${GeneratedGRPCSource}
    PARTIAL_SOURCES_INTENDED
    LINK_LIBS grpc++ protobuf)
endfunction()