caffe: fuck compile error again : error: a value of type "const float *" cannot be used to initialize an entity of type "float *"

wangxiao@wangxiao-GTX980:~/Downloads/caffe-master$ make -j8
find: `wangxiao/bvlc_alexnet/spl': No such file or directory
find: `caffemodel': No such file or directory
find: `wangxiao/bvlc_alexnet/0.77': No such file or directory
find: `caffemodel': No such file or directory
NVCC src/caffe/layers/euclidean_loss_layer.cu
src/caffe/layers/euclidean_loss_layer.cu(41): error: a value of type "const float *" cannot be used to initialize an entity of type "float *"
          detected during instantiation of "void caffe::EuclideanLossLayer<Dtype>::Backward_gpu(const std::vector<caffe::Blob<Dtype> *, std::allocator<caffe::Blob<Dtype> *>> &, const std::vector<__nv_bool, std::allocator<__nv_bool>> &, const std::vector<caffe::Blob<Dtype> *, std::allocator<caffe::Blob<Dtype> *>> &) [with Dtype=float]"
(140): here

src/caffe/layers/euclidean_loss_layer.cu(42): error: a value of type "const float *" cannot be used to initialize an entity of type "float *"
          detected during instantiation of "void caffe::EuclideanLossLayer<Dtype>::Backward_gpu(const std::vector<caffe::Blob<Dtype> *, std::allocator<caffe::Blob<Dtype> *>> &, const std::vector<__nv_bool, std::allocator<__nv_bool>> &, const std::vector<caffe::Blob<Dtype> *, std::allocator<caffe::Blob<Dtype> *>> &) [with Dtype=float]"
(140): here

src/caffe/layers/euclidean_loss_layer.cu(41): error: a value of type "const double *" cannot be used to initialize an entity of type "double *"
          detected during instantiation of "void caffe::EuclideanLossLayer<Dtype>::Backward_gpu(const std::vector<caffe::Blob<Dtype> *, std::allocator<caffe::Blob<Dtype> *>> &, const std::vector<__nv_bool, std::allocator<__nv_bool>> &, const std::vector<caffe::Blob<Dtype> *, std::allocator<caffe::Blob<Dtype> *>> &) [with Dtype=double]"
(140): here

src/caffe/layers/euclidean_loss_layer.cu(42): error: a value of type "const double *" cannot be used to initialize an entity of type "double *"
          detected during instantiation of "void caffe::EuclideanLossLayer<Dtype>::Backward_gpu(const std::vector<caffe::Blob<Dtype> *, std::allocator<caffe::Blob<Dtype> *>> &, const std::vector<__nv_bool, std::allocator<__nv_bool>> &, const std::vector<caffe::Blob<Dtype> *, std::allocator<caffe::Blob<Dtype> *>> &) [with Dtype=double]"
(140): here

4 errors detected in the compilation of "/tmp/tmpxft_000007e5_00000000-16_euclidean_loss_layer.compute_50.cpp1.ii".
make: *** [.build_debug/cuda/src/caffe/layers/euclidean_loss_layer.o] Error 1
wangxiao@wangxiao-GTX980:~/Downloads/caffe-master$

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原因分析：

主要是因为，在欧式距离损失函数中，我增添了以下两句话：

Dtype* diff_cpu_data = bottom[i]->mutable_cpu_diff();
       Dtype* label_data = bottom[1]->cpu_data();    // label data: 0 or 1
       Dtype* predict_data = bottom[0]->cpu_data();  // predict data

再来看看提示的错误：

src/caffe/layers/euclidean_loss_layer.cu(41): error: a value of type "const float *" cannot be used to initialize an entity of type "float *"
         
detected during instantiation of "void
caffe::EuclideanLossLayer<Dtype>::Backward_gpu(const
std::vector<caffe::Blob<Dtype> *,
std::allocator<caffe::Blob<Dtype> *>> &, const
std::vector<__nv_bool, std::allocator<__nv_bool>> &,
const std::vector<caffe::Blob<Dtype> *,
std::allocator<caffe::Blob<Dtype> *>> &) [with
Dtype=float]"
(140): here

src/caffe/layers/euclidean_loss_layer.cu(42): error: a value of type "const float *" cannot be used to initialize an entity of type "float *"
         
detected during instantiation of "void
caffe::EuclideanLossLayer<Dtype>::Backward_gpu(const
std::vector<caffe::Blob<Dtype> *,
std::allocator<caffe::Blob<Dtype> *>> &, const
std::vector<__nv_bool, std::allocator<__nv_bool>> &,
const std::vector<caffe::Blob<Dtype> *,
std::allocator<caffe::Blob<Dtype> *>> &) [with
Dtype=float]"
(140): here

肯定是少了 const 约束：

so , 改为：

const Dtype* label_data = bottom[1]->cpu_data();    // label data: 0 or 1
const Dtype* predict_data = bottom[0]->cpu_data();  // predict data

在编译，就ok啦 ～～

2. 问题2：

CXX src/caffe/layers/accuracy_layer.cpp
src/caffe/layers/accuracy_layer.cpp: In instantiation of ‘void caffe::AccuracyLayer<Dtype>::Forward_cpu(const std::vector<caffe::Blob<Dtype>*>&, const std::vector<caffe::Blob<Dtype>*>&) [with Dtype = float]’:
src/caffe/layers/accuracy_layer.cpp:286:1:   required from here
src/caffe/layers/accuracy_layer.cpp:98:21: error: assignment of read-only location ‘*(bottom_data + 84u)’
     bottom_data[21] = 1; bottom_data[22] = 0; bottom_data[23] = 0; bottom_data[24] = 0;

看到错误就应该知道：错误的原因是给只读的变量赋值了。。。

但是，又想改变那个值，来作为最后求解的结果，怎么办呢？ 好吧，那就只好先将该变量存到一个中间变量里面去了，但是，问题又来了，原本const 的变量可以赋值给普通的变量么？

例如： float a = const float b ? 这样ok么？我觉得不ok，先试试吧。。。