Reject lower version of gRPC.

Signed-off-by: Tao He <sighingnow@gmail.com>

CMakeLists.txt

@@ -87,7 +87,12 @@ else()
     include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/FindGRPC.cmake)
     set(GRPC_LIBRARIES ${GPR_LIBRARY} ${GRPC_LIBRARY} ${GRPC_GRPC++_LIBRARY})
 endif()
-
+if(gRPC_FOUND AND gRPC_VERSION VERSION_LESS "1.13")
+    message(FATAL_ERROR "gRPC '${gRPC_VERSION}' is not supported, please install a newer gRPC library "
+                        "by following the example below"
+                        "\n"
+                        "    https://github.com/etcd-cpp-apiv3/etcd-cpp-apiv3/blob/master/.github/workflows/build-test.yml#L50-L75")
+endif()
 include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/GenerateProtobufGRPC.cmake)
 
 # will set `PROTOBUF_GENERATES`, indicates all generated .cc files, and a target `protobuf_generates`.

cmake/FindGRPC.cmake

@@ -67,6 +67,32 @@ set_target_properties(gRPC::grpc_cpp_plugin PROPERTIES
     IMPORTED_LOCATION ${GRPC_CPP_PLUGIN}
 )
 
+file(
+    WRITE "${CMAKE_BINARY_DIR}/get_gRPC_version.cc"
+[====[
+#include <grpc++/grpc++.h>
+#include <iostream>
+int main() {
+  std::cout << grpc::Version(); // no newline to simplify CMake module
+  return 0;
+}
+]====])
+
+try_run(
+    _gRPC_GET_VERSION_STATUS
+    _gRPC_GET_VERSION_COMPILE_STATUS
+    "${CMAKE_BINARY_DIR}"
+    "${CMAKE_BINARY_DIR}/get_gRPC_version.cc"
+    LINK_LIBRARIES
+    gRPC::grpc++
+    gRPC::grpc
+    COMPILE_OUTPUT_VARIABLE _gRPC_GET_VERSION_COMPILE_OUTPUT
+    RUN_OUTPUT_VARIABLE gRPC_VERSION)
+
+file(REMOVE "${CMAKE_BINARY_DIR}/get_gRPC_version.cc")
+
 include(${CMAKE_ROOT}/Modules/FindPackageHandleStandardArgs.cmake)
-FIND_PACKAGE_HANDLE_STANDARD_ARGS(gRPC DEFAULT_MSG
-    GPR_LIBRARY GRPC_LIBRARY GRPC_INCLUDE_DIR GRPC_GRPC++_REFLECTION_LIBRARY GRPC_CPP_PLUGIN)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(gRPC
+  FOUND_VAR gRPC_FOUND
+  REQUIRED_VARS GRPC_LIBRARY GPR_LIBRARY GRPC_INCLUDE_DIR GRPC_GRPC++_REFLECTION_LIBRARY GRPC_CPP_PLUGIN
+  VERSION_VAR gRPC_VERSION)