Merge pull request #24372 from Kumataro:fix24369

Supporting protobuf v22 and later(with abseil-cpp/C++17) #24372

fix https://github.com/opencv/opencv/issues/24369
related https://github.com/opencv/opencv/issues/23791

1. This patch supports external protobuf v22 and later, it required abseil-cpp and c++17.
    Even if the built-in protobuf is upgraded to v22 or later, 
    the dependency on abseil-cpp and the requirement for C++17 will continue.
2. Some test for caffe required patched protobuf, so this patch disable them.

This patch is tested by following libraries.
-  Protobuf:                    /usr/local/lib/libprotobuf.so (4.24.4)
-  abseil-cpp:                YES (20230125)

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

cmake/OpenCVFindProtobuf.cmake

@@ -30,8 +30,14 @@ if(BUILD_PROTOBUF)
   set(Protobuf_LIBRARIES "libprotobuf")
   set(HAVE_PROTOBUF TRUE)
 else()
+  # we still need this for command PROTOBUF_GENERATE_CPP.
+  set(protobuf_MODULE_COMPATIBLE ON)
+
   unset(Protobuf_VERSION CACHE)
-  find_package(Protobuf QUIET)
+  find_package(Protobuf QUIET CONFIG)
+  if(NOT Protobuf_FOUND)
+    find_package(Protobuf QUIET)
+  endif()
 
   # Backwards compatibility
   # Define camel case versions of input variables
@@ -67,6 +73,20 @@ else()
   endif()
 endif()
 
+# See https://github.com/opencv/opencv/issues/24369
+# In Protocol Buffers v22.0 and later drops C++11 support and depends abseil-cpp.
+#   Details: https://protobuf.dev/news/2022-08-03/
+# And if std::text_view is in abseil-cpp requests C++17 and later.
+
+if(HAVE_PROTOBUF)
+  if(NOT (Protobuf_VERSION VERSION_LESS 22))
+    if((CMAKE_CXX_STANDARD EQUAL 98) OR (CMAKE_CXX_STANDARD LESS 17))
+      message(STATUS "CMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD} is too old to support protobuf(${Protobuf_VERSION}) and/or abseil-cpp. Use C++17 or later. Turning HAVE_PROTOBUF off")
+      set(HAVE_PROTOBUF FALSE)
+    endif()
+  endif()
+endif()
+
 if(HAVE_PROTOBUF AND PROTOBUF_UPDATE_FILES AND NOT COMMAND PROTOBUF_GENERATE_CPP)
   message(FATAL_ERROR "Can't configure protobuf dependency (BUILD_PROTOBUF=${BUILD_PROTOBUF} PROTOBUF_UPDATE_FILES=${PROTOBUF_UPDATE_FILES})")
 endif()
@@ -74,15 +94,20 @@ endif()
 if(HAVE_PROTOBUF)
   list(APPEND CUSTOM_STATUS protobuf)
   if(NOT BUILD_PROTOBUF)
+    unset( __location)
     if(TARGET "${Protobuf_LIBRARIES}")
       get_target_property(__location "${Protobuf_LIBRARIES}" IMPORTED_LOCATION_RELEASE)
       if(NOT __location)
         get_target_property(__location "${Protobuf_LIBRARIES}" IMPORTED_LOCATION)
       endif()
-    elseif(Protobuf_LIBRARY)
-      set(__location "${Protobuf_LIBRARY}")
-    else()
-      set(__location "${Protobuf_LIBRARIES}")
+    endif()
+
+    if(NOT __location)
+      if(Protobuf_LIBRARY)
+        set(__location "${Protobuf_LIBRARY}")
+      else()
+        set(__location "${Protobuf_LIBRARIES}")
+      endif()
     endif()
   endif()
   list(APPEND CUSTOM_STATUS_protobuf "    Protobuf:"

modules/dnn/CMakeLists.txt

@@ -240,6 +240,12 @@ ocv_create_module(${libs} ${dnn_runtime_libs})
 ocv_add_samples()
 ocv_add_accuracy_tests(${dnn_runtime_libs})
 
+if(NOT BUILD_PROTOBUF)
+  if(TARGET opencv_test_dnn)
+    ocv_target_compile_definitions(opencv_test_dnn PRIVATE "OPENCV_DNN_EXTERNAL_PROTOBUF=1")
+  endif()
+endif()
+
 set(perf_path "${CMAKE_CURRENT_LIST_DIR}/perf")
 file(GLOB_RECURSE perf_srcs "${perf_path}/*.cpp")
 file(GLOB_RECURSE perf_hdrs "${perf_path}/*.hpp" "${perf_path}/*.h")

modules/dnn/test/test_layers.cpp

@@ -764,11 +764,15 @@ TEST_F(Layer_RNN_Test, get_set_test)
 
 TEST_P(Test_Caffe_layers, Accum)
 {
+#ifdef OPENCV_DNN_EXTERNAL_PROTOBUF
+    throw SkipTestException("Requires patched protobuf");
+#else
     if (backend == DNN_BACKEND_OPENCV && target != DNN_TARGET_CPU)
         applyTestTag(CV_TEST_TAG_DNN_SKIP_OPENCL, CV_TEST_TAG_DNN_SKIP_OPENCL_FP16);
 
     testLayerUsingCaffeModels("accum", false, false, 0.0, 0.0, 2);
     testLayerUsingCaffeModels("accum_ref", false, false, 0.0, 0.0, 2);
+#endif
 }
 
 TEST_P(Test_Caffe_layers, FlowWarp)
@@ -788,29 +792,41 @@ TEST_P(Test_Caffe_layers, ChannelNorm)
 
 TEST_P(Test_Caffe_layers, DataAugmentation)
 {
+#ifdef OPENCV_DNN_EXTERNAL_PROTOBUF
+    throw SkipTestException("Requires patched protobuf");
+#else
     if (backend == DNN_BACKEND_OPENCV && target == DNN_TARGET_OPENCL_FP16)
         applyTestTag(CV_TEST_TAG_DNN_SKIP_OPENCL_FP16);
     testLayerUsingCaffeModels("data_augmentation", true, false);
     testLayerUsingCaffeModels("data_augmentation_2x1", true, false);
     testLayerUsingCaffeModels("data_augmentation_8x6", true, false);
+#endif
 }
 
 TEST_P(Test_Caffe_layers, Resample)
 {
+#ifdef OPENCV_DNN_EXTERNAL_PROTOBUF
+    throw SkipTestException("Requires patched protobuf");
+#else
 #if defined(INF_ENGINE_RELEASE) && INF_ENGINE_VER_MAJOR_LT(2023000000)
     if (backend != DNN_BACKEND_OPENCV)
         applyTestTag(CV_TEST_TAG_DNN_SKIP_IE_NN_BUILDER, CV_TEST_TAG_DNN_SKIP_IE_NGRAPH);
 #endif
     testLayerUsingCaffeModels("nearest_2inps", false, false, 0.0, 0.0, 2);
     testLayerUsingCaffeModels("nearest", false, false);
+#endif
 }
 
 TEST_P(Test_Caffe_layers, Correlation)
 {
+#ifdef OPENCV_DNN_EXTERNAL_PROTOBUF
+    throw SkipTestException("Requires patched protobuf");
+#else
     if (backend == DNN_BACKEND_OPENCV && target == DNN_TARGET_OPENCL_FP16)
         applyTestTag(CV_TEST_TAG_DNN_SKIP_IE_NGRAPH, CV_TEST_TAG_DNN_SKIP_IE_NN_BUILDER,
                      CV_TEST_TAG_DNN_SKIP_OPENCL, CV_TEST_TAG_DNN_SKIP_OPENCL_FP16);
     testLayerUsingCaffeModels("correlation", false, false, 0.0, 0.0, 2);
+#endif
 }
 
 TEST_P(Test_Caffe_layers, Convolution2Inputs)
@@ -1651,12 +1667,11 @@ private:
     int outWidth, outHeight, zoomFactor;
 };
 
-#ifndef OPENCV_DNN_EXTERNAL_PROTOBUF
 TEST_P(Test_Caffe_layers, Interp)
-#else
-TEST_P(Test_Caffe_layers, DISABLED_Interp)  // requires patched protobuf (available in OpenCV source tree only)
-#endif
 {
+#ifdef OPENCV_DNN_EXTERNAL_PROTOBUF
+    throw SkipTestException("Requires patched protobuf");
+#else
 #if defined(INF_ENGINE_RELEASE) && INF_ENGINE_VER_MAJOR_EQ(2021030000)
     if (backend == DNN_BACKEND_INFERENCE_ENGINE_NGRAPH && target == DNN_TARGET_MYRIAD)
         applyTestTag(CV_TEST_TAG_DNN_SKIP_IE_MYRIAD, CV_TEST_TAG_DNN_SKIP_IE_NGRAPH);  // exception
@@ -1680,6 +1695,7 @@ TEST_P(Test_Caffe_layers, DISABLED_Interp)  // requires patched protobuf (availa
 
     // Test an implemented layer.
     testLayerUsingCaffeModels("layer_interp", false, false);
+#endif
 }
 
 INSTANTIATE_TEST_CASE_P(/*nothing*/, Test_Caffe_layers, dnnBackendsAndTargets());