Re: [meta-oe][PATCH v2 1/2] grpc: add cmake support for target


Stefan Herbrechtsmeier
 

Hi Clement,

Am 08.04.2022 um 14:25 schrieb Clément Péron:
Hi Stefan,
On Fri, 8 Apr 2022 at 09:30, Stefan Herbrechtsmeier
<stefan.herbrechtsmeier-oss@...> wrote:

From: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@...>

The CMake gRPC config checks for binaries and fails if a binary (plugin)
is missing. Fix the problem in the code and add the CMake gRPC config
back to the target package.
Thanks for your patch, I'm still using gRPC 1.35 + your previous similar patch.
I'm trying to bump to gRPC 1.45.1 + these patches.
My recipe use CMake and depends on grpc and grpc-native:
PACKAGECONFIG[grpc] = "-DCONFIG_GRPC=ON,-DCONFIG_GRPC=OFF,grpc grpc-native"
But unfortunately CMake doesn't find the grpc_cpp_plugin.
This is the correct behavior of my patch because the grpc_cpp_plugin from the cross build isn't usable during cross build. You need the grpc_cpp_plugin from the host and therefore have to search the grpc_cpp_plugin by yourself during cross compile [1].

My first patch was rejected and therefore I create a minimal patch which only make the CMake gRPC config usable.

| -- Using gRPC 1.45.1
....
| CMake Error at modules/grpc/CMakeLists.txt:37 (add_custom_command):
| Error evaluating generator expression:
|
| $<TARGET_FILE:gRPC::grpc_cpp_plugin>
|
| No target "gRPC::grpc_cpp_plugin"
|
|
| CMake Error at modules/grpc/CMakeLists.txt:37 (add_custom_command):
| Error evaluating generator expression:
|
| $<TARGET_FILE:gRPC::grpc_cpp_plugin>
|
| No target "gRPC::grpc_cpp_plugin"
|
|
| CMake Error at modules/grpc/CMakeLists.txt:37 (add_custom_command):
| Error evaluating generator expression:
|
| $<TARGET_FILE:gRPC::grpc_cpp_plugin>
|
| No target "gRPC::grpc_cpp_plugin"
Here is my CMake source file:
# Find Protobuf installation Yocto SDK doensn't support protobuf-config.cmake
# for the moment
set(protobuf_MODULE_COMPATIBLE TRUE)
find_package(Protobuf REQUIRED)
message(STATUS "Using protobuf ${Protobuf_VERSION}")
set(_PROTOBUF_LIBPROTOBUF protobuf::libprotobuf)
# Find gRPC installation Looks for gRPCConfig.cmake file installed by gRPC's
# cmake installation.
find_package(gRPC CONFIG REQUIRED)
message(STATUS "Using gRPC ${gRPC_VERSION}")
set(_REFLECTION gRPC::grpc++_reflection)
set(_GRPC_GRPCPP gRPC::grpc++)
# Get full path of protobuf/gRPC compiler
set(_PROTOBUF_PROTOC $<TARGET_FILE:protobuf::protoc>)
set(_GRPC_CPP_PLUGIN_EXECUTABLE $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
You have to search the binaries if you cross compile [1]:

if(CMAKE_CROSSCOMPILING)
find_program(_GRPC_CPP_PLUGIN_EXECUTABLE grpc_cpp_plugin)
else()
set(_GRPC_CPP_PLUGIN_EXECUTABLE $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
endif()

Do you have an example of how you look for gRPC in your recipe?
This isn't possible because you use a target and not a variable.

[1] https://github.com/grpc/grpc/blob/master/examples/cpp/cmake/common.cmake

Regards
Stefan

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