diff --git a/3rdparty/ittnotify/CMakeLists.txt b/3rdparty/ittnotify/CMakeLists.txt
index a227aff88e..0f39adcd4b 100644
--- a/3rdparty/ittnotify/CMakeLists.txt
+++ b/3rdparty/ittnotify/CMakeLists.txt
@@ -54,6 +54,7 @@ set_target_properties(${ITT_LIBRARY} PROPERTIES
     )
 
 ocv_warnings_disable(CMAKE_C_FLAGS -Wundef -Wsign-compare)
+ocv_warnings_disable(CMAKE_C_FLAGS -Wstrict-prototypes) # clang15
 
 if(ENABLE_SOLUTION_FOLDERS)
   set_target_properties(${ITT_LIBRARY} PROPERTIES FOLDER "3rdparty")
diff --git a/3rdparty/libpng/CMakeLists.txt b/3rdparty/libpng/CMakeLists.txt
index efa59627eb..bb0f3dd2c5 100644
--- a/3rdparty/libpng/CMakeLists.txt
+++ b/3rdparty/libpng/CMakeLists.txt
@@ -78,6 +78,8 @@ add_library(${PNG_LIBRARY} STATIC ${OPENCV_3RDPARTY_EXCLUDE_FROM_ALL} ${lib_srcs
 target_link_libraries(${PNG_LIBRARY} ${ZLIB_LIBRARIES})
 
 ocv_warnings_disable(CMAKE_C_FLAGS -Wundef -Wcast-align -Wimplicit-fallthrough -Wunused-parameter -Wsign-compare)
+ocv_warnings_disable(CMAKE_C_FLAGS -Wnull-pointer-subtraction)  # clang15
+ocv_warnings_disable(CMAKE_C_FLAGS -Wunused-but-set-variable)  # clang15
 
 set_target_properties(${PNG_LIBRARY}
   PROPERTIES OUTPUT_NAME ${PNG_LIBRARY}
diff --git a/3rdparty/libtiff/CMakeLists.txt b/3rdparty/libtiff/CMakeLists.txt
index 2074888a52..d37cfff337 100644
--- a/3rdparty/libtiff/CMakeLists.txt
+++ b/3rdparty/libtiff/CMakeLists.txt
@@ -454,6 +454,7 @@ ocv_warnings_disable(CMAKE_C_FLAGS -Wno-unused-but-set-variable -Wmissing-protot
                                    -Wimplicit-fallthrough
 )
 ocv_warnings_disable(CMAKE_C_FLAGS -Wunused-parameter) # clang
+ocv_warnings_disable(CMAKE_C_FLAGS -Wstrict-prototypes) # clang15
 ocv_warnings_disable(CMAKE_CXX_FLAGS -Wmissing-declarations -Wunused-parameter -Wmissing-prototypes
     -Wundef  # tiffiop.h: #if __clang_major__ >= 4
 )
diff --git a/3rdparty/libwebp/CMakeLists.txt b/3rdparty/libwebp/CMakeLists.txt
index 9160e2024c..723575c8db 100644
--- a/3rdparty/libwebp/CMakeLists.txt
+++ b/3rdparty/libwebp/CMakeLists.txt
@@ -45,6 +45,7 @@ ocv_warnings_disable(CMAKE_C_FLAGS -Wunused-variable -Wunused-function -Wshadow
     -Wmissing-prototypes  # clang
     -Wmissing-declarations # gcc
     -Wimplicit-fallthrough
+    -Wunused-but-set-variable # clang15
 )
 ocv_warnings_disable(CMAKE_C_FLAGS /wd4244 /wd4267) # vs2005
 
diff --git a/3rdparty/openjpeg/CMakeLists.txt b/3rdparty/openjpeg/CMakeLists.txt
index fe766101d0..42730bab2b 100644
--- a/3rdparty/openjpeg/CMakeLists.txt
+++ b/3rdparty/openjpeg/CMakeLists.txt
@@ -13,6 +13,7 @@ project(openjpeg C)
 
 ocv_warnings_disable(CMAKE_C_FLAGS
     -Wimplicit-const-int-float-conversion  # clang
+    -Wunused-but-set-variable # clang15
 )
 
 #-----------------------------------------------------------------------------
diff --git a/modules/calib3d/src/calibinit.cpp b/modules/calib3d/src/calibinit.cpp
index e25dd26d21..9e96802388 100644
--- a/modules/calib3d/src/calibinit.cpp
+++ b/modules/calib3d/src/calibinit.cpp
@@ -1469,7 +1469,7 @@ int ChessBoardDetector::checkQuadGroup(std::vector<ChessBoardQuad*>& quad_group,
     first = below; // remember the first corner in the next row
 
     // find and store the first row (or column)
-    for (int j = 1; ; ++j)
+    while( 1 )
     {
         right->row = 0;
         out_corners.push_back(right);
diff --git a/modules/calib3d/test/test_cameracalibration.cpp b/modules/calib3d/test/test_cameracalibration.cpp
index c1704ad928..1c04bb78dd 100644
--- a/modules/calib3d/test/test_cameracalibration.cpp
+++ b/modules/calib3d/test/test_cameracalibration.cpp
@@ -568,12 +568,7 @@ void CV_CameraCalibrationTest::run( int start_from )
         /* ----- Compute reprojection error ----- */
         double dx,dy;
         double rx,ry;
-        double meanDx,meanDy;
-        double maxDx = 0.0;
-        double maxDy = 0.0;
 
-        meanDx = 0;
-        meanDy = 0;
         for( currImage = 0; currImage < numImages; currImage++ )
         {
             double imageMeanDx = 0;
@@ -585,20 +580,8 @@ void CV_CameraCalibrationTest::run( int start_from )
                 dx = rx - imagePoints[currImage][currPoint].x;
                 dy = ry - imagePoints[currImage][currPoint].y;
 
-                meanDx += dx;
-                meanDy += dy;
-
                 imageMeanDx += dx*dx;
                 imageMeanDy += dy*dy;
-
-                dx = fabs(dx);
-                dy = fabs(dy);
-
-                if( dx > maxDx )
-                    maxDx = dx;
-
-                if( dy > maxDy )
-                    maxDy = dy;
             }
             goodPerViewErrors[currImage] = sqrt( (imageMeanDx + imageMeanDy) /
                                            (etalonSize.width * etalonSize.height));
@@ -609,9 +592,6 @@ void CV_CameraCalibrationTest::run( int start_from )
                 perViewErrors[currImage] = goodPerViewErrors[currImage];
         }
 
-        meanDx /= numImages * etalonSize.width * etalonSize.height;
-        meanDy /= numImages * etalonSize.width * etalonSize.height;
-
         /* ========= Compare parameters ========= */
         CV_Assert(cameraMatrix.type() == CV_64F && cameraMatrix.size() == Size(3, 3));
         CV_Assert(distortion.type() == CV_64F);
diff --git a/modules/calib3d/test/test_fisheye.cpp b/modules/calib3d/test/test_fisheye.cpp
index ad3b066a6a..7e40493db3 100644
--- a/modules/calib3d/test/test_fisheye.cpp
+++ b/modules/calib3d/test/test_fisheye.cpp
@@ -227,7 +227,7 @@ TEST_F(fisheyeTest, undistortAndDistortImage)
     cv::Mat undPointsGt(imageHeight, imageWidth, CV_32FC2);
     cv::Mat imageGt(imageHeight, imageWidth, CV_8UC3);
 
-    for(int y = 0, k = 0; y < imageHeight; ++y)
+    for(int y = 0; y < imageHeight; ++y)
     {
         for(int x = 0; x < imageWidth; ++x)
         {
@@ -261,7 +261,6 @@ TEST_F(fisheyeTest, undistortAndDistortImage)
                 pixel_gt[2] = pixel[2];
             }
 
-            k++;
         }
     }
 
diff --git a/modules/core/perf/opencl/perf_matop.cpp b/modules/core/perf/opencl/perf_matop.cpp
index 5be1f431f6..b763a98e2a 100644
--- a/modules/core/perf/opencl/perf_matop.cpp
+++ b/modules/core/perf/opencl/perf_matop.cpp
@@ -233,6 +233,7 @@ PERF_TEST_P_(OpenCLBuffer, cpu_read)
             for (size_t x_bytes = 0; x_bytes < width_bytes; x_bytes++)
                 counter += (unsigned)(ptr[x_bytes]);
         }
+        (void)counter; // To avoid -Wunused-but-set-variable
     }
 
     SANITY_CHECK_NOTHING();
diff --git a/modules/core/src/datastructs.cpp b/modules/core/src/datastructs.cpp
index eec7ade02b..80b02283dc 100644
--- a/modules/core/src/datastructs.cpp
+++ b/modules/core/src/datastructs.cpp
@@ -133,8 +133,6 @@ cvCreateChildMemStorage( CvMemStorage * parent )
 static void
 icvDestroyMemStorage( CvMemStorage* storage )
 {
-    int k = 0;
-
     CvMemBlock *block;
     CvMemBlock *dst_top = 0;
 
@@ -144,7 +142,7 @@ icvDestroyMemStorage( CvMemStorage* storage )
     if( storage->parent )
         dst_top = storage->parent->top;
 
-    for( block = storage->bottom; block != 0; k++ )
+    for( block = storage->bottom; block != 0; )
     {
         CvMemBlock *temp = block;
 
diff --git a/modules/core/src/lpsolver.cpp b/modules/core/src/lpsolver.cpp
index 951da3fd7f..43fa73a025 100644
--- a/modules/core/src/lpsolver.cpp
+++ b/modules/core/src/lpsolver.cpp
@@ -253,11 +253,8 @@ static int initialize_simplex(Mat_<double>& c, Mat_<double>& b,double& v,vector<
 }
 
 static int inner_simplex(Mat_<double>& c, Mat_<double>& b,double& v,vector<int>& N,vector<int>& B,vector<unsigned int>& indexToRow){
-    int count=0;
-    for(;;){
-        dprintf(("iteration #%d\n",count));
-        count++;
 
+    for(;;){
         static MatIterator_<double> pos_ptr;
         int e=-1,pos_ctr=0,min_var=INT_MAX;
         bool all_nonzero=true;
diff --git a/modules/core/src/trace.cpp b/modules/core/src/trace.cpp
index 1011db5e3b..05acbde7c9 100644
--- a/modules/core/src/trace.cpp
+++ b/modules/core/src/trace.cpp
@@ -988,7 +988,6 @@ void parallelForFinalize(const Region& rootRegion)
     std::vector<TraceManagerThreadLocal*> threads_ctx;
     getTraceManager().tls.gather(threads_ctx);
     RegionStatistics parallel_for_stat;
-    int threads = 0;
     for (size_t i = 0; i < threads_ctx.size(); i++)
     {
         TraceManagerThreadLocal* child_ctx = threads_ctx[i];
@@ -996,7 +995,6 @@ void parallelForFinalize(const Region& rootRegion)
         if (child_ctx && child_ctx->stackTopRegion() == &rootRegion)
         {
             CV_LOG_PARALLEL(NULL, "Thread=" << child_ctx->threadID << " " << child_ctx->stat);
-            threads++;
             RegionStatistics child_stat;
             child_ctx->stat.grab(child_stat);
             parallel_for_stat.append(child_stat);
@@ -1012,6 +1010,7 @@ void parallelForFinalize(const Region& rootRegion)
             }
         }
     }
+
     float parallel_coeff = std::min(1.0f, duration / (float)(parallel_for_stat.duration));
     CV_LOG_PARALLEL(NULL, "parallel_coeff=" << 1.0f / parallel_coeff);
     CV_LOG_PARALLEL(NULL, parallel_for_stat);
diff --git a/modules/features2d/src/evaluation.cpp b/modules/features2d/src/evaluation.cpp
index ca7ab14500..7135891e0d 100644
--- a/modules/features2d/src/evaluation.cpp
+++ b/modules/features2d/src/evaluation.cpp
@@ -315,6 +315,8 @@ struct SIdx
         const SIdx& used;
         bool operator()(const SIdx& v) const { return  (v.i1 == used.i1 || v.i2 == used.i2); }
         UsedFinder& operator=(const UsedFinder&) = delete;
+        // To avoid -Wdeprecated-copy warning, copy constructor is needed.
+        UsedFinder(const UsedFinder&) = default;
     };
 };
 
diff --git a/modules/features2d/src/kaze/KAZEFeatures.cpp b/modules/features2d/src/kaze/KAZEFeatures.cpp
index ab591d417c..7bd0ba6dcd 100644
--- a/modules/features2d/src/kaze/KAZEFeatures.cpp
+++ b/modules/features2d/src/kaze/KAZEFeatures.cpp
@@ -312,7 +312,7 @@ void KAZEFeatures::Determinant_Hessian(std::vector<KeyPoint>& kpts)
 {
     int level = 0;
     float smax = 3.0;
-    int npoints = 0, id_repeated = 0;
+    int id_repeated = 0;
     int left_x = 0, right_x = 0, up_y = 0, down_y = 0;
     bool is_extremum = false, is_repeated = false, is_out = false;
 
@@ -383,7 +383,6 @@ void KAZEFeatures::Determinant_Hessian(std::vector<KeyPoint>& kpts)
                 if (is_out == false) {
                     if (is_repeated == false) {
                         kpts.push_back(kpts_par_ij);
-                        npoints++;
                     }
                     else {
                         kpts[id_repeated] = kpts_par_ij;
diff --git a/modules/features2d/src/keypoint.cpp b/modules/features2d/src/keypoint.cpp
index e14c9da94c..21d9eb30f7 100644
--- a/modules/features2d/src/keypoint.cpp
+++ b/modules/features2d/src/keypoint.cpp
@@ -148,10 +148,12 @@ public:
     {
         return mask.at<uchar>( (int)(key_pt.pt.y + 0.5f), (int)(key_pt.pt.x + 0.5f) ) == 0;
     }
+    MaskPredicate& operator=(const MaskPredicate&) = delete;
+    // To avoid -Wdeprecated-copy warning, copy constructor is needed.
+    MaskPredicate(const MaskPredicate&) = default;
 
 private:
     const Mat mask;
-    MaskPredicate& operator=(const MaskPredicate&) = delete;
 };
 
 void KeyPointsFilter::runByPixelsMask( std::vector<KeyPoint>& keypoints, const Mat& mask )
diff --git a/modules/flann/include/opencv2/flann/index_testing.h b/modules/flann/include/opencv2/flann/index_testing.h
index 207adef449..4c00143326 100644
--- a/modules/flann/include/opencv2/flann/index_testing.h
+++ b/modules/flann/include/opencv2/flann/index_testing.h
@@ -246,7 +246,6 @@ void test_index_precisions(NNIndex<Distance>& index, const Matrix<typename Dista
     float p2;
 
     int c1 = 1;
-    float p1;
 
     float time;
     DistanceType dist;
@@ -270,7 +269,6 @@ void test_index_precisions(NNIndex<Distance>& index, const Matrix<typename Dista
         precision = precisions[i];
         while (p2<precision) {
             c1 = c2;
-            p1 = p2;
             c2 *=2;
             p2 = search_with_ground_truth(index, inputData, testData, matches, nn, c2, time, dist, distance, skipMatches);
             if ((maxTime> 0)&&(time > maxTime)&&(p2<precision)) return;
diff --git a/modules/gapi/src/compiler/passes/exec.cpp b/modules/gapi/src/compiler/passes/exec.cpp
index f6a73489eb..93d833d602 100644
--- a/modules/gapi/src/compiler/passes/exec.cpp
+++ b/modules/gapi/src/compiler/passes/exec.cpp
@@ -606,7 +606,9 @@ namespace
         MergeContext mc;
 
         bool there_was_a_merge = false;
+#ifdef DEBUG_MERGE
         std::size_t iteration = 0u;
+#endif
         do
         {
             there_was_a_merge = false;
@@ -615,8 +617,8 @@ namespace
 #ifdef DEBUG_MERGE
             GAPI_LOG_INFO(NULL, "Before next merge attempt " << iteration << "...");
             merge_debug(g, iteration);
-#endif
             iteration++;
+#endif
             auto sorted = pass_helpers::topoSort(im);
             for (auto nh : sorted)
             {
diff --git a/modules/gapi/test/s11n/gapi_s11n_tests.cpp b/modules/gapi/test/s11n/gapi_s11n_tests.cpp
index 94b99f877a..22398ec92c 100644
--- a/modules/gapi/test/s11n/gapi_s11n_tests.cpp
+++ b/modules/gapi/test/s11n/gapi_s11n_tests.cpp
@@ -569,7 +569,6 @@ TEST_F(S11N_Basic, Test_Bind_RunArgs_MatScalar) {
     v[0] = cv::GRunArg{ mat };
     v[1] = cv::GRunArg{ scalar };
     GRunArgsP output = cv::gapi::bind(v);
-    unsigned int i = 0;
     for (auto it : output)
     {
         using T = cv::GRunArgP;
@@ -591,7 +590,6 @@ TEST_F(S11N_Basic, Test_Bind_RunArgs_MatScalar) {
             GAPI_Assert(false && "This value type is not supported!"); // ...maybe because of STANDALONE mode.
             break;
         }
-        i++;
     }
 }
 
diff --git a/modules/imgproc/test/test_approxpoly.cpp b/modules/imgproc/test/test_approxpoly.cpp
index aace416b97..f09475c9fc 100644
--- a/modules/imgproc/test/test_approxpoly.cpp
+++ b/modules/imgproc/test/test_approxpoly.cpp
@@ -220,6 +220,7 @@ int CV_ApproxPolyTest::check_slice( CvPoint StartPt, CvPoint EndPt,
 
     *_j = j;
 
+    (void) TotalErrors; // To avoid -Wunused-but-set-variable warning
     //return TotalErrors;
     return 0;
 }
diff --git a/modules/ml/src/kdtree.cpp b/modules/ml/src/kdtree.cpp
index a80e12964a..8cdab98f73 100644
--- a/modules/ml/src/kdtree.cpp
+++ b/modules/ml/src/kdtree.cpp
@@ -120,16 +120,13 @@ medianPartition( size_t* ofs, int a, int b, const float* vals )
     }
 
     float pivot = vals[ofs[middle]];
-    int less = 0, more = 0;
     for( k = a0; k < middle; k++ )
     {
         CV_Assert(vals[ofs[k]] <= pivot);
-        less += vals[ofs[k]] < pivot;
     }
     for( k = b0; k > middle; k-- )
     {
         CV_Assert(vals[ofs[k]] >= pivot);
-        more += vals[ofs[k]] > pivot;
     }
 
     return vals[ofs[middle]];
diff --git a/modules/stitching/src/motion_estimators.cpp b/modules/stitching/src/motion_estimators.cpp
index c0b46b101d..29616a4915 100644
--- a/modules/stitching/src/motion_estimators.cpp
+++ b/modules/stitching/src/motion_estimators.cpp
@@ -262,7 +262,9 @@ bool BundleAdjusterBase::estimate(const std::vector<ImageFeatures> &features,
     CvMat matParams = cvMat(cam_params_);
     cvCopy(&matParams, solver.param);
 
+#if ENABLE_LOG
     int iter = 0;
+#endif
     for(;;)
     {
         const CvMat* _param = 0;
@@ -287,7 +289,9 @@ bool BundleAdjusterBase::estimate(const std::vector<ImageFeatures> &features,
         {
             calcError(err);
             LOG_CHAT(".");
+#if ENABLE_LOG
             iter++;
+#endif
             CvMat tmp = cvMat(err);
             cvCopy(&tmp, _err);
         }
diff --git a/modules/video/test/test_optflowpyrlk.cpp b/modules/video/test/test_optflowpyrlk.cpp
index 905cfebafa..a79a0ff4e4 100644
--- a/modules/video/test/test_optflowpyrlk.cpp
+++ b/modules/video/test/test_optflowpyrlk.cpp
@@ -64,10 +64,9 @@ void CV_OptFlowPyrLKTest::run( int )
     const int bad_points_max = 8;
 
     /* test parameters */
-    double  max_err = 0., sum_err = 0;
-    int     pt_cmpd = 0;
+    double  max_err = 0.;
     int     pt_exceed = 0;
-    int     merr_i = 0, merr_j = 0, merr_k = 0, merr_nan = 0;
+    int     merr_i = 0, merr_nan = 0;
     char    filename[1000];
 
     cv::Point2f *v = 0, *v2 = 0;
@@ -155,7 +154,6 @@ void CV_OptFlowPyrLKTest::run( int )
             double err;
             if( cvIsNaN(v[i].x) || cvIsNaN(v[i].y) )
             {
-                merr_j++;
                 continue;
             }
 
@@ -173,15 +171,12 @@ void CV_OptFlowPyrLKTest::run( int )
             }
 
             pt_exceed += err > success_error_level;
-            sum_err += err;
-            pt_cmpd++;
         }
         else
         {
             if( !cvIsNaN( v[i].x ))
             {
                 merr_i = i;
-                merr_k++;
                 ts->printf( cvtest::TS::LOG, "The algorithm lost the point #%d\n", i );
                 code = cvtest::TS::FAIL_BAD_ACCURACY;
                 break;
diff --git a/modules/video/test/test_trackers.impl.hpp b/modules/video/test/test_trackers.impl.hpp
index 5ae98d1eb8..fc2315ced0 100644
--- a/modules/video/test/test_trackers.impl.hpp
+++ b/modules/video/test/test_trackers.impl.hpp
@@ -336,7 +336,6 @@ void TrackerTest<Tracker, ROI_t>::checkDataTest()
     gt2.open(gtFile.c_str());
     ASSERT_TRUE(gt2.is_open()) << gtFile;
     string line2;
-    int bbCounter2 = 0;
     while (getline(gt2, line2))
     {
         vector<string> tokens = splitString(line2, ",");
@@ -344,7 +343,6 @@ void TrackerTest<Tracker, ROI_t>::checkDataTest()
         ASSERT_EQ((size_t)4, tokens.size()) << "Incorrect ground truth file " << gtFile;
 
         bbs.push_back(bb);
-        bbCounter2++;
     }
     gt2.close();