Add the hint to find the host grpc_cpp_plugin when crosscompiling

gRPC doesn't provide the smart tool lookup when crosscompiling.
So gRPC lookup is unable to find the grpc_cpp_plugin plugin when
crosscompiling examples. Use find_program to find the plugin in
host paths.

Pick-to: 6.8 6.9
Fixes: QTBUG-134647
Change-Id: I961b180b348dee4f1b2f2523be225d3003847e4c
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Dennis Oberst <dennis.oberst@qt.io>

examples/grpc/chat/server/CMakeLists.txt

@@ -18,7 +18,15 @@ find_package(Qt6 COMPONENTS ProtobufTools ProtobufQtCoreTypes)
 find_package(Protobuf)
 find_package(gRPC)
 
-if(NOT TARGET gRPC::grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
+if(CMAKE_CROSSCOMPILING)
+    find_program(grpc_cpp_plugin grpc_cpp_plugin NO_CACHE)
+elseif(TARGET gRPC::grpc_cpp_plugin)
+    set(grpc_cpp_plugin $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
+else()
+    set(grpc_cpp_plugin "")
+endif()
+
+if(NOT grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
         OR NOT TARGET gRPC::grpc++ OR NOT TARGET Qt6::ProtobufQtCoreTypes
         OR NOT TARGET gRPC::grpc++_reflection)
     message(WARNING "Dependencies of ${PROJECT_NAME} not found. Skipping.")
@@ -57,7 +65,7 @@ add_custom_command(
     ARGS
     --grpc_out "${proto_out}"
     --cpp_out "${proto_out}"
-    --plugin=protoc-gen-grpc=$<TARGET_FILE:gRPC::grpc_cpp_plugin>
+    --plugin=protoc-gen-grpc=${grpc_cpp_plugin}
     ${proto_includes}
     ${proto_files}
     WORKING_DIRECTORY ${proto_out}

examples/grpc/clientguide/server/CMakeLists.txt

@@ -10,7 +10,15 @@ find_package(protobuf)
 find_package(gRPC)
 find_package(Qt6 COMPONENTS ProtobufTools)
 
-if(NOT TARGET gRPC::grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
+if(CMAKE_CROSSCOMPILING)
+    find_program(grpc_cpp_plugin grpc_cpp_plugin NO_CACHE)
+elseif(TARGET gRPC::grpc_cpp_plugin)
+    set(grpc_cpp_plugin $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
+else()
+    set(grpc_cpp_plugin "")
+endif()
+
+if(NOT grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
     OR NOT TARGET gRPC::grpc++)
     message(WARNING "Dependencies of ${PROJECT_NAME} not found. Skipping.")
     return()
@@ -36,7 +44,7 @@ add_custom_command(
         --grpc_out "${proto_out}"
         --cpp_out "${proto_out}"
         -I "${CMAKE_CURRENT_LIST_DIR}/../proto"
-        --plugin=protoc-gen-grpc=$<TARGET_FILE:gRPC::grpc_cpp_plugin>
+        --plugin=protoc-gen-grpc=${grpc_cpp_plugin}
         "${proto_files}"
     WORKING_DIRECTORY ${proto_out}
     DEPENDS "${proto_files}"

examples/grpc/magic8ball/server/CMakeLists.txt

@@ -9,7 +9,15 @@ set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
 find_package(Protobuf)
 find_package(gRPC)
 
-if(NOT TARGET gRPC::grpc_cpp_plugin OR NOT TARGET gRPC::grpc++)
+if(CMAKE_CROSSCOMPILING)
+    find_program(grpc_cpp_plugin grpc_cpp_plugin NO_CACHE)
+elseif(TARGET gRPC::grpc_cpp_plugin)
+    set(grpc_cpp_plugin $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
+else()
+    set(grpc_cpp_plugin "")
+endif()
+
+if(NOT grpc_cpp_plugin OR NOT TARGET gRPC::grpc++)
     return()
 endif()
 
@@ -38,7 +46,7 @@ add_custom_command(
     --grpc_out "${out_dir}"
     --cpp_out "${out_dir}"
     -I "${CMAKE_CURRENT_LIST_DIR}/../proto/"
-    --plugin=protoc-gen-grpc=$<TARGET_FILE:gRPC::grpc_cpp_plugin>
+    --plugin=protoc-gen-grpc=${grpc_cpp_plugin}
     "${proto_files}"
     WORKING_DIRECTORY ${out_dir}
     DEPENDS "${proto_files}"

examples/grpc/vehicle/server/CMakeLists.txt

@@ -9,7 +9,15 @@ set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
 find_package(Protobuf)
 find_package(gRPC)
 
-if(NOT TARGET gRPC::grpc_cpp_plugin OR NOT TARGET gRPC::grpc++)
+if(CMAKE_CROSSCOMPILING)
+    find_program(grpc_cpp_plugin grpc_cpp_plugin NO_CACHE)
+elseif(TARGET gRPC::grpc_cpp_plugin)
+    set(grpc_cpp_plugin $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
+else()
+    set(grpc_cpp_plugin "")
+endif()
+
+if(NOT grpc_cpp_plugin OR NOT TARGET gRPC::grpc++)
     return()
 endif()
 
@@ -41,7 +49,7 @@ add_custom_command(
     --grpc_out "${out_dir}"
     --cpp_out "${out_dir}"
     -I "${CMAKE_CURRENT_LIST_DIR}/../proto/"
-    --plugin=protoc-gen-grpc=$<TARGET_FILE:gRPC::grpc_cpp_plugin>
+    --plugin=protoc-gen-grpc=${grpc_cpp_plugin}
     "${proto_files}"
     WORKING_DIRECTORY ${out_dir}
     DEPENDS "${proto_files}"

tests/auto/grpc/client/shared/test_server/CMakeLists.txt

@@ -6,7 +6,15 @@ set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
 find_package(Protobuf)
 find_package(gRPC)
 
-if(NOT TARGET gRPC::grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
+if(CMAKE_CROSSCOMPILING)
+    find_program(grpc_cpp_plugin grpc_cpp_plugin NO_CACHE)
+elseif(TARGET gRPC::grpc_cpp_plugin)
+    set(grpc_cpp_plugin $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
+else()
+    set(grpc_cpp_plugin "")
+endif()
+
+if(NOT grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
     OR NOT TARGET gRPC::grpc++)
     message(WARNING "Dependencies of Qt GRPC test server not found. Skipping.")
     return()
@@ -34,7 +42,7 @@ add_custom_command(
         --grpc_out "${out_dir}"
         --cpp_out "${out_dir}"
         -I "${CMAKE_CURRENT_LIST_DIR}/../../../shared/proto/"
-        --plugin=protoc-gen-grpc=$<TARGET_FILE:gRPC::grpc_cpp_plugin>
+        --plugin=protoc-gen-grpc=${grpc_cpp_plugin}
         "${proto_files}"
     WORKING_DIRECTORY ${out_dir}
     DEPENDS "${proto_files}" $<TARGET_FILE:WrapProtoc::WrapProtoc>

tests/manual/grpc/benchmarks/asyncbenchserver/CMakeLists.txt

@@ -5,7 +5,15 @@ find_package(WrapProtoc)
 find_package(Protobuf)
 find_package(gRPC)
 
-if(NOT TARGET gRPC::grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
+if(CMAKE_CROSSCOMPILING)
+    find_program(grpc_cpp_plugin grpc_cpp_plugin NO_CACHE)
+elseif(TARGET gRPC::grpc_cpp_plugin)
+    set(grpc_cpp_plugin $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
+else()
+    set(grpc_cpp_plugin "")
+endif()
+
+if(NOT grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
     OR NOT TARGET gRPC::grpc++)
     message(WARNING "Dependencies of QtGrpc benchmark-server not found. Skipping.")
     return()
@@ -36,13 +44,13 @@ add_custom_command(
         --grpc_out "${proto_out_dir}"
         --cpp_out "${proto_out_dir}"
         -I "${proto_include}"
-        --plugin=protoc-gen-grpc=$<TARGET_FILE:gRPC::grpc_cpp_plugin>
+        --plugin=protoc-gen-grpc=${grpc_cpp_plugin}
         "${proto_path}"
     WORKING_DIRECTORY "${proto_out_dir}"
     DEPENDS
         "${proto_path}"
         $<TARGET_FILE:WrapProtoc::WrapProtoc>
-        $<TARGET_FILE:gRPC::grpc_cpp_plugin>
+        ${grpc_cpp_plugin}
     COMMENT "Generating gRPC ${target} sources..."
     COMMAND_EXPAND_LISTS
     VERBATIM
@@ -65,4 +73,3 @@ qt_internal_add_executable(
     OUTPUT_DIRECTORY
         "${CMAKE_CURRENT_BINARY_DIR}"
 )
-

tests/manual/grpc/benchmarks/bench_async_ref_client/CMakeLists.txt

@@ -5,7 +5,15 @@ find_package(WrapProtoc)
 find_package(Protobuf)
 find_package(gRPC)
 
-if(NOT TARGET gRPC::grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
+if(CMAKE_CROSSCOMPILING)
+    find_program(grpc_cpp_plugin grpc_cpp_plugin NO_CACHE)
+elseif(TARGET gRPC::grpc_cpp_plugin)
+    set(grpc_cpp_plugin $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
+else()
+    set(grpc_cpp_plugin "")
+endif()
+
+if(NOT grpc_cpp_plugin OR NOT TARGET WrapProtoc::WrapProtoc
     OR NOT TARGET gRPC::grpc++)
     message(WARNING "Dependencies of QtGrpc bench_async_ref_client not found. Skipping.")
     return()
@@ -36,13 +44,13 @@ add_custom_command(
         --grpc_out "${proto_out_dir}"
         --cpp_out "${proto_out_dir}"
         -I "${proto_include}"
-        --plugin=protoc-gen-grpc=$<TARGET_FILE:gRPC::grpc_cpp_plugin>
+        --plugin=protoc-gen-grpc=${grpc_cpp_plugin}
         "${proto_path}"
     WORKING_DIRECTORY "${proto_out_dir}"
     DEPENDS
         "${proto_path}"
         $<TARGET_FILE:WrapProtoc::WrapProtoc>
-        $<TARGET_FILE:gRPC::grpc_cpp_plugin>
+        ${grpc_cpp_plugin}
     COMMENT "Generating gRPC ${target} sources..."
     COMMAND_EXPAND_LISTS
     VERBATIM