Could you fix ncnn build warning？

[ArmstrongYang]

ncnn build success but warning:

Scanning dependencies of target ncnn
[  1%] Building CXX object src/CMakeFiles/ncnn.dir/allocator.cpp.o
[  2%] Building CXX object src/CMakeFiles/ncnn.dir/blob.cpp.o
[  3%] Building CXX object src/CMakeFiles/ncnn.dir/cpu.cpp.o
[  5%] Building CXX object src/CMakeFiles/ncnn.dir/layer.cpp.o
[  6%] Building CXX object src/CMakeFiles/ncnn.dir/mat.cpp.o
[  7%] Building CXX object src/CMakeFiles/ncnn.dir/mat_pixel.cpp.o
[  8%] Building CXX object src/CMakeFiles/ncnn.dir/modelbin.cpp.o
[ 10%] Building CXX object src/CMakeFiles/ncnn.dir/net.cpp.o
/home/rd-dyang/workspace/ncnn/src/net.cpp: In member function ‘int ncnn::Net::load_param(FILE*)’:
/home/rd-dyang/workspace/ncnn/src/net.cpp:106:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     fscanf(fp, "%d", &magic);
                             ^
/home/rd-dyang/workspace/ncnn/src/net.cpp:116:51: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     fscanf(fp, "%d %d", &layer_count, &blob_count);
                                                   ^
/home/rd-dyang/workspace/ncnn/src/net.cpp: In member function ‘int ncnn::Net::load_param_bin(FILE*)’:
/home/rd-dyang/workspace/ncnn/src/net.cpp:403:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fread(&magic, sizeof(int), 1, fp);
                                      ^
/home/rd-dyang/workspace/ncnn/src/net.cpp:411:44: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fread(&layer_count, sizeof(int), 1, fp);
                                            ^
/home/rd-dyang/workspace/ncnn/src/net.cpp:414:43: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fread(&blob_count, sizeof(int), 1, fp);
                                           ^
/home/rd-dyang/workspace/ncnn/src/net.cpp:427:46: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&typeindex, sizeof(int), 1, fp);
                                              ^
/home/rd-dyang/workspace/ncnn/src/net.cpp:430:49: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&bottom_count, sizeof(int), 1, fp);
                                                 ^
/home/rd-dyang/workspace/ncnn/src/net.cpp:433:46: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&top_count, sizeof(int), 1, fp);
                                              ^
/home/rd-dyang/workspace/ncnn/src/net.cpp:456:58: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&bottom_blob_index, sizeof(int), 1, fp);
                                                          ^
/home/rd-dyang/workspace/ncnn/src/net.cpp:469:55: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&top_blob_index, sizeof(int), 1, fp);
                                                       ^
[ 11%] Building CXX object src/CMakeFiles/ncnn.dir/opencv.cpp.o
[ 12%] Building CXX object src/CMakeFiles/ncnn.dir/paramdict.cpp.o
/home/rd-dyang/workspace/ncnn/src/paramdict.cpp: In member function ‘int ncnn::ParamDict::load_param_bin(FILE*)’:
/home/rd-dyang/workspace/ncnn/src/paramdict.cpp:305:35: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fread(&id, sizeof(int), 1, fp);
                                   ^
/home/rd-dyang/workspace/ncnn/src/paramdict.cpp:318:44: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&len, sizeof(int), 1, fp);
                                            ^
/home/rd-dyang/workspace/ncnn/src/paramdict.cpp:323:47: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(ptr, sizeof(float), len, fp);
                                               ^
/home/rd-dyang/workspace/ncnn/src/paramdict.cpp:327:55: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&params[id].f, sizeof(float), 1, fp);
                                                       ^
/home/rd-dyang/workspace/ncnn/src/paramdict.cpp:332:39: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&id, sizeof(int), 1, fp);
                                       ^
[ 13%] Building CXX object src/CMakeFiles/ncnn.dir/benchmark.cpp.o
[ 15%] Building CXX object src/CMakeFiles/ncnn.dir/layer/absval.cpp.o
[ 16%] Building CXX object src/CMakeFiles/ncnn.dir/layer/batchnorm.cpp.o
[ 17%] Building CXX object src/CMakeFiles/ncnn.dir/layer/bias.cpp.o
[ 18%] Building CXX object src/CMakeFiles/ncnn.dir/layer/bnll.cpp.o
[ 20%] Building CXX object src/CMakeFiles/ncnn.dir/layer/concat.cpp.o
[ 21%] Building CXX object src/CMakeFiles/ncnn.dir/layer/convolution.cpp.o
[ 22%] Building CXX object src/CMakeFiles/ncnn.dir/layer/x86/convolution_x86.cpp.o
[ 23%] Building CXX object src/CMakeFiles/ncnn.dir/layer/crop.cpp.o
[ 25%] Building CXX object src/CMakeFiles/ncnn.dir/layer/deconvolution.cpp.o
[ 26%] Building CXX object src/CMakeFiles/ncnn.dir/layer/dropout.cpp.o
[ 27%] Building CXX object src/CMakeFiles/ncnn.dir/layer/eltwise.cpp.o
[ 28%] Building CXX object src/CMakeFiles/ncnn.dir/layer/elu.cpp.o
[ 30%] Building CXX object src/CMakeFiles/ncnn.dir/layer/embed.cpp.o
[ 31%] Building CXX object src/CMakeFiles/ncnn.dir/layer/exp.cpp.o
[ 32%] Building CXX object src/CMakeFiles/ncnn.dir/layer/flatten.cpp.o
[ 33%] Building CXX object src/CMakeFiles/ncnn.dir/layer/innerproduct.cpp.o
[ 35%] Building CXX object src/CMakeFiles/ncnn.dir/layer/input.cpp.o
[ 36%] Building CXX object src/CMakeFiles/ncnn.dir/layer/log.cpp.o
[ 37%] Building CXX object src/CMakeFiles/ncnn.dir/layer/lrn.cpp.o
[ 38%] Building CXX object src/CMakeFiles/ncnn.dir/layer/memorydata.cpp.o
[ 40%] Building CXX object src/CMakeFiles/ncnn.dir/layer/mvn.cpp.o
[ 41%] Building CXX object src/CMakeFiles/ncnn.dir/layer/pooling.cpp.o
[ 42%] Building CXX object src/CMakeFiles/ncnn.dir/layer/power.cpp.o
[ 43%] Building CXX object src/CMakeFiles/ncnn.dir/layer/prelu.cpp.o
[ 45%] Building CXX object src/CMakeFiles/ncnn.dir/layer/proposal.cpp.o
[ 46%] Building CXX object src/CMakeFiles/ncnn.dir/layer/reduction.cpp.o
[ 47%] Building CXX object src/CMakeFiles/ncnn.dir/layer/relu.cpp.o
[ 48%] Building CXX object src/CMakeFiles/ncnn.dir/layer/reshape.cpp.o
[ 50%] Building CXX object src/CMakeFiles/ncnn.dir/layer/roipooling.cpp.o
[ 51%] Building CXX object src/CMakeFiles/ncnn.dir/layer/scale.cpp.o
[ 52%] Building CXX object src/CMakeFiles/ncnn.dir/layer/sigmoid.cpp.o
[ 53%] Building CXX object src/CMakeFiles/ncnn.dir/layer/slice.cpp.o
[ 55%] Building CXX object src/CMakeFiles/ncnn.dir/layer/softmax.cpp.o
[ 56%] Building CXX object src/CMakeFiles/ncnn.dir/layer/split.cpp.o
[ 57%] Building CXX object src/CMakeFiles/ncnn.dir/layer/tanh.cpp.o
[ 58%] Building CXX object src/CMakeFiles/ncnn.dir/layer/threshold.cpp.o
[ 60%] Building CXX object src/CMakeFiles/ncnn.dir/layer/binaryop.cpp.o
[ 61%] Building CXX object src/CMakeFiles/ncnn.dir/layer/unaryop.cpp.o
[ 62%] Building CXX object src/CMakeFiles/ncnn.dir/layer/convolutiondepthwise.cpp.o
[ 63%] Building CXX object src/CMakeFiles/ncnn.dir/layer/x86/convolutiondepthwise_x86.cpp.o
[ 65%] Building CXX object src/CMakeFiles/ncnn.dir/layer/padding.cpp.o
[ 66%] Building CXX object src/CMakeFiles/ncnn.dir/layer/squeeze.cpp.o
[ 67%] Building CXX object src/CMakeFiles/ncnn.dir/layer/expanddims.cpp.o
[ 68%] Building CXX object src/CMakeFiles/ncnn.dir/layer/normalize.cpp.o
[ 70%] Building CXX object src/CMakeFiles/ncnn.dir/layer/permute.cpp.o
[ 71%] Building CXX object src/CMakeFiles/ncnn.dir/layer/priorbox.cpp.o
[ 72%] Building CXX object src/CMakeFiles/ncnn.dir/layer/detectionoutput.cpp.o
[ 73%] Building CXX object src/CMakeFiles/ncnn.dir/layer/interp.cpp.o
[ 75%] Building CXX object src/CMakeFiles/ncnn.dir/layer/deconvolutiondepthwise.cpp.o
[ 76%] Building CXX object src/CMakeFiles/ncnn.dir/layer/shufflechannel.cpp.o
[ 77%] Building CXX object src/CMakeFiles/ncnn.dir/layer/instancenorm.cpp.o
[ 78%] Building CXX object src/CMakeFiles/ncnn.dir/layer/clip.cpp.o
[ 80%] Building CXX object src/CMakeFiles/ncnn.dir/layer/reorg.cpp.o
[ 81%] Building CXX object src/CMakeFiles/ncnn.dir/layer/yolodetectionoutput.cpp.o
[ 82%] Building CXX object src/CMakeFiles/ncnn.dir/layer/quantize.cpp.o
[ 83%] Building CXX object src/CMakeFiles/ncnn.dir/layer/dequantize.cpp.o
[ 85%] Linking CXX static library libncnn.a
[ 85%] Built target ncnn
Scanning dependencies of target ncnn2mem
[ 86%] Building CXX object tools/CMakeFiles/ncnn2mem.dir/ncnn2mem.cpp.o
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp: In function ‘int dump_param(const char*, const char*, const char*)’:
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp:229:21: warning: name lookup of ‘i’ changed
         layer_names[i] = std::string(layer_name);
                     ^
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp:106:14: warning:   matches this ‘i’ under ISO standard rules
     for (int i=0; i<layer_count; i++)
              ^
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp:131:18: warning:   matches this ‘i’ under old rules
         for (int i=0; i<bottom_count; i++)
                  ^
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp:93:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     fscanf(fp, "%d", &magic);
                             ^
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp:98:51: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     fscanf(fp, "%d %d", &layer_count, &blob_count);
                                                   ^
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp:180:39: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
                 fscanf(fp, "%d", &len);
                                       ^
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp:186:52: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
                     fscanf(fp, ",%15[^,\n ]", vstr);
                                                    ^
/home/rd-dyang/workspace/ncnn/tools/ncnn2mem.cpp:207:41: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
                 fscanf(fp, "%15s", vstr);
                                         ^
[ 87%] Linking CXX executable ncnn2mem
[ 87%] Built target ncnn2mem
[ 88%] Running C++ protocol buffer compiler on caffe.proto
Scanning dependencies of target caffe2ncnn
[ 90%] Building CXX object tools/caffe/CMakeFiles/caffe2ncnn.dir/caffe2ncnn.cpp.o
[ 91%] Building CXX object tools/caffe/CMakeFiles/caffe2ncnn.dir/caffe.pb.cc.o
[ 92%] Linking CXX executable caffe2ncnn
[ 92%] Built target caffe2ncnn
Scanning dependencies of target mxnet2ncnn
[ 93%] Building CXX object tools/mxnet/CMakeFiles/mxnet2ncnn.dir/mxnet2ncnn.cpp.o
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp: In function ‘int main(int, char**)’:
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:1833:17: warning: unused variable ‘squeeze_axis’ [-Wunused-variable]
             int squeeze_axis = n.attr("squeeze_axis");// TODO
                 ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp: In function ‘bool read_mxnet_json(const char*, std::vector<MXNetNode>&)’:
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:272:26: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fgets(line, 1024, fp);
                          ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp: In function ‘bool read_mxnet_param(const char*, std::vector<MXNetParam>&)’:
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:499:44: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fread(&header, 1, sizeof(uint64_t), fp);
                                            ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:500:46: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fread(&reserved, 1, sizeof(uint64_t), fp);
                                              ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:506:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fread(&data_count, 1, sizeof(uint64_t), fp);
                                                ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:513:47: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&magic, 1, sizeof(uint32_t), fp);
                                               ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:522:50: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&stype, 1, sizeof(int32_t), fp);
                                                  ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:524:50: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&ndim, 1, sizeof(uint32_t), fp);
                                                  ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:527:60: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&shape[0], 1, ndim * sizeof(int64_t), fp);
                                                            ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:531:50: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&ndim, 1, sizeof(uint32_t), fp);
                                                  ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:534:60: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&shape[0], 1, ndim * sizeof(int64_t), fp);
                                                            ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:544:63: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
             fread(&shape32[0], 1, ndim * sizeof(uint32_t), fp);
                                                               ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:555:49: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&dev_type, 1, sizeof(int32_t), fp);
                                                 ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:556:47: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&dev_id, 1, sizeof(int32_t), fp);
                                               ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:559:50: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&type_flag, 1, sizeof(int32_t), fp);
                                                  ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:571:54: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&p.data[0], 1, len * sizeof(float), fp);
                                                      ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:580:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     fread(&name_count, 1, sizeof(uint64_t), fp);
                                                ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:587:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(&len, 1, sizeof(uint64_t), fp);
                                             ^
/home/rd-dyang/workspace/ncnn/tools/mxnet/mxnet2ncnn.cpp:592:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread((char*)p.name.data(), 1, len, fp);
                                                ^
[ 95%] Linking CXX executable mxnet2ncnn
[ 95%] Built target mxnet2ncnn
[ 96%] Running C++ protocol buffer compiler on onnx.proto
Scanning dependencies of target onnx2ncnn
[ 97%] Building CXX object tools/onnx/CMakeFiles/onnx2ncnn.dir/onnx2ncnn.cpp.o
/home/rd-dyang/workspace/ncnn/tools/onnx/onnx2ncnn.cpp: In function ‘int main(int, char**)’:
/home/rd-dyang/workspace/ncnn/tools/onnx/onnx2ncnn.cpp:440:32: warning: unused variable ‘output_name’ [-Wunused-variable]
             const std::string& output_name = node.output(j);
                                ^
/home/rd-dyang/workspace/ncnn/tools/onnx/onnx2ncnn.cpp:1191:81: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘google::protobuf::int64 {aka long int}’ [-Wformat=]
                     fprintf(stderr, "  # %s=%d\n", attr.name().c_str(), attr.i());
                                                                                 ^
[ 98%] Building CXX object tools/onnx/CMakeFiles/onnx2ncnn.dir/onnx.pb.cc.o
[100%] Linking CXX executable onnx2ncnn
[100%] Built target onnx2ncnn

[lippman1125]

so many warnnings

[dlml]

警告没事啊

[nihui]

these warnings are not critical :)