when cross-compiling, the host grpc_cpp_plugin should be used

CMakeLists.txt

@@ -190,6 +190,13 @@ function(protobuf_generate_grpc_cpp)
     get_filename_component(REL_DIR ${REL_FIL} DIRECTORY)
     set(RELFIL_WE "${REL_DIR}/${FIL_WE}")
 
+    #if cross-compiling, find host plugin
+    if(CMAKE_CROSSCOMPILING)
+        find_program(gRPC_CPP_PLUGIN grpc_cpp_plugin)
+    else()
+        set(gRPC_CPP_PLUGIN $<TARGET_FILE:grpc_cpp_plugin>)
+    endif()
+
     add_custom_command(
       OUTPUT "${_gRPC_PROTO_GENS_DIR}/${RELFIL_WE}.grpc.pb.cc"
              "${_gRPC_PROTO_GENS_DIR}/${RELFIL_WE}.grpc.pb.h"
@@ -199,7 +206,7 @@ function(protobuf_generate_grpc_cpp)
       COMMAND ${_gRPC_PROTOBUF_PROTOC_EXECUTABLE}
       ARGS --grpc_out=generate_mock_code=true:${_gRPC_PROTO_GENS_DIR}
            --cpp_out=${_gRPC_PROTO_GENS_DIR}
-           --plugin=protoc-gen-grpc=$<TARGET_FILE:grpc_cpp_plugin>
+           --plugin=protoc-gen-grpc=${gRPC_CPP_PLUGIN}
            ${_protobuf_include_path}
            ${REL_FIL}
       DEPENDS ${ABS_FIL} ${_gRPC_PROTOBUF_PROTOC} grpc_cpp_plugin

templates/CMakeLists.txt.template

@@ -239,6 +239,13 @@
       get_filename_component(REL_DIR <%text>${REL_FIL}</%text> DIRECTORY)
       set(RELFIL_WE "<%text>${REL_DIR}/${FIL_WE}</%text>")
 
+      #if cross-compiling, find host plugin
+      if(CMAKE_CROSSCOMPILING)
+          find_program(gRPC_CPP_PLUGIN grpc_cpp_plugin)
+      else()
+          set(gRPC_CPP_PLUGIN $<TARGET_FILE:grpc_cpp_plugin>)
+      endif()
+
       add_custom_command(
         OUTPUT <%text>"${_gRPC_PROTO_GENS_DIR}/${RELFIL_WE}.grpc.pb.cc"</%text>
                <%text>"${_gRPC_PROTO_GENS_DIR}/${RELFIL_WE}.grpc.pb.h"</%text>
@@ -248,7 +255,7 @@
         COMMAND <%text>${_gRPC_PROTOBUF_PROTOC_EXECUTABLE}</%text>
         ARGS --grpc_out=<%text>generate_mock_code=true:${_gRPC_PROTO_GENS_DIR}</%text>
              --cpp_out=<%text>${_gRPC_PROTO_GENS_DIR}</%text>
-             --plugin=protoc-gen-grpc=$<TARGET_FILE:grpc_cpp_plugin>
+             --plugin=protoc-gen-grpc=<%text>${gRPC_CPP_PLUGIN}</%text>
              <%text>${_protobuf_include_path}</%text>
              <%text>${REL_FIL}</%text>
         DEPENDS <%text>${ABS_FIL}</%text> <%text>${_gRPC_PROTOBUF_PROTOC}</%text> grpc_cpp_plugin