C++ 带特征张量示例的编译器警告

我正在用不受支持的本征张量库做一些实验。在文档中，有一个小示例显示如何调整张量对象的大小：

Tensor<float, 3> t_3d(2, 3, 4);
t_3d = Tensor<float, 3>(3, 4, 3);

张量t_-3d（2,3,4）；
t_3d=张量（3,4,3）；

当我编译一个main（）时，它基本上由这两行组成，我从编译器那里得到了一大堆废话：

In file included from /usr/local/include/eigen3/unsupported/Eigen/CXX11/Tensor:88:0,
                 from tensor_test.cpp:6:
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h: In instantiation of ‘struct Eigen::TensorEvaluator<const Eigen::Tensor<float, 3>, Eigen::DefaultDevice>’:
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorAssign.h:96:70:   required from ‘struct Eigen::TensorEvaluator<const Eigen::TensorAssignOp<Eigen::Tensor<float, 3>, const Eigen::Tensor<float, 3> >, Eigen::DefaultDevice>’
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/Tensor.h:406:14:   required from ‘Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>& Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>::operator=(const Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>&) [with Scalar_ = float; int NumIndices_ = 3; int Options_ = 0; IndexType_ = long int]’
tensor_test.cpp:29:36:   required from here
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:156:71: warning: ignoring attributes on template argument ‘Eigen::PacketType<float, Eigen::DefaultDevice>::type {aka __vector(4) float}’ [-Wignored-attributes]
     PacketAccess = (internal::unpacket_traits<PacketReturnType>::size > 1),
                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h: In instantiation of ‘struct Eigen::TensorEvaluator<Eigen::Tensor<float, 3>, Eigen::DefaultDevice>’:
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorAssign.h:100:65:   required from ‘struct Eigen::TensorEvaluator<const Eigen::TensorAssignOp<Eigen::Tensor<float, 3>, const Eigen::Tensor<float, 3> >, Eigen::DefaultDevice>’
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/Tensor.h:406:14:   required from ‘Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>& Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>::operator=(const Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>&) [with Scalar_ = float; int NumIndices_ = 3; int Options_ = 0; IndexType_ = long int]’
tensor_test.cpp:29:36:   required from here
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:42:71: warning: ignoring attributes on template argument ‘Eigen::PacketType<float, Eigen::DefaultDevice>::type {aka __vector(4) float}’ [-Wignored-attributes]
     PacketAccess = (internal::unpacket_traits<PacketReturnType>::size > 1),
                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
In file included from /usr/local/include/eigen3/unsupported/Eigen/CXX11/Tensor:121:0,
                 from tensor_test.cpp:6:
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorExecutor.h: In instantiation of ‘static void Eigen::internal::TensorExecutor<Expression, Eigen::DefaultDevice, true>::run(const Expression&, const Eigen::DefaultDevice&) [with Expression = const Eigen::TensorAssignOp<Eigen::Tensor<float, 3>, const Eigen::Tensor<float, 3> >]’:
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/Tensor.h:407:65:   required from ‘Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>& Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>::operator=(const Eigen::Tensor<Scalar_, NumIndices_, Options_, IndexType>&) [with Scalar_ = float; int NumIndices_ = 3; int Options_ = 0; IndexType_ = long int]’
tensor_test.cpp:29:36:   required from here
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorExecutor.h:61:17: warning: ignoring attributes on template argument ‘Eigen::TensorEvaluator<const Eigen::TensorAssignOp<Eigen::Tensor<float, 3>, const Eigen::Tensor<float, 3> >, Eigen::DefaultDevice>::PacketReturnType {aka __vector(4) float}’ [-Wignored-attributes]
       const int PacketSize = unpacket_traits<typename TensorEvaluator<Expression, DefaultDevice>::PacketReturnType>::size;

在/usr/local/include/eigen3/unsupported/Eigen/CXX11/Tensor:88:0中包含的文件中，
来自张量_检验。cpp:6：
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:在“struct-Eigen:：TensorEvaluator”的实例化中：
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorAssign.h:96:70:必须来自“结构特征：：TensorEvaluator”
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/Tensor.h:406:14:必须来自“Eigen:：Tensor&Eigen:：Tensor:：operator=（const-Eigen:：Tensor&）[带标量=float；int-NumIndices=3；int-Options=0；IndexType=long-int]”
张量测试。cpp:29:36：从这里开始需要
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:156:71：警告：忽略模板参数'Eigen:：PacketType:：type{aka__vector（4）float}'[-Wignored attributes]上的属性
PacketAccess=（内部：：解包特征：：大小>1），
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:在“struct-Eigen:：TensorEvaluator”的实例化中：
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorAssign.h:100:65:必须来自“struct Eigen:：TensorEvaluator”
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/Tensor.h:406:14:必须来自“Eigen:：Tensor&Eigen:：Tensor:：operator=（const-Eigen:：Tensor&）[带标量=float；int-NumIndices=3；int-Options=0；IndexType=long-int]”
张量测试。cpp:29:36：从这里开始需要
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:42:71：警告：忽略模板参数'Eigen:：PacketType:：type{aka__vector（4）float}'[-Wignored attributes]上的属性
PacketAccess=（内部：：解包特征：：大小>1），
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
在/usr/local/include/eigen3/unsupported/Eigen/cx11/Tensor:121:0中包含的文件中，
来自张量_检验。cpp:6：
/usr/local/include/eigen3/unsupported/Eigen/cx11/src/Tensor/TensorExecutor.h:在“static void Eigen:：internal:：TensorExecutor:：run（const Expression&，const Eigen:：DefaultDevice&）[with Expression=const Eigen:：TensorAssignOp]的实例化中：
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/Tensor.h:407:65:必须来自“Eigen:：Tensor&Eigen:：Tensor:：operator=（const-Eigen:：Tensor&）[带标量=float；int-NumIndices=3；int-Options=0；IndexType=long-int]]
张量测试。cpp:29:36：从这里开始需要
/usr/local/include/eigen3/unsupported/Eigen/CXX11/src/Tensor/TensorExecutor.h:61:17：警告：忽略模板参数“Eigen:：TensorEvaluator:：PacketReturnType{aka__向量（4）float}”[-Wignored属性]
const int PacketSize=unpacket_traits:：size；

我可以添加一个填充张量的小代码，然后打印出内容，然后一切都按预期进行：

for (auto ii = 0; ii < 3; ii++) {
    for (auto jj = 0; jj < 4; jj++) {
        for (auto kk = 0; kk < 3; kk++) {
            t_3d(kk, jj, ii) = val++;
        }
    }
}
for (auto ii = 0; ii < 3; ii++) {
    for (auto jj = 0; jj < 4; jj++) {
        for (auto kk = 0; kk < 3; kk++) {
            std::cout << t_3d(kk, jj, ii) << std::endl;
        }
    }
}

用于（自动ii=0；ii<3；ii++）{ 用于（自动jj=0；jj<4；jj++）{ 用于（自动kk=0；kk<3；kk++）{ t_3d（kk，jj，ii）=val++； } } } 用于（自动ii=0；ii<3；ii++）{ 用于（自动jj=0；jj<4；jj++）{ 用于（自动kk=0；kk<3；kk++）{

---

std：：cout我能够使用g++的

-isystem

选项关闭来自

不支持的/Eigen/CXX11/src/Tensor

的警告

---

我使用的是

gcc版本7.4.0

和

Eigen版本3.3.7（323c052e1731）

我很久以前就放弃了压制eigen的警告。它会让人感到温暖。只要它还在做你想做的事情，就忽略它。@Jeffrey我可能会这么做。我还发现boost是一个丰富的笨拙编译器消息源……你使用的是eigen的最新开发版本吗？如果你是，并且你遇到了这些警告，你会记录一个bug报告（同时说明您正在使用的编译器和编译标志）。如果您不关心修复警告，请通过

-isystem

而不是

-I

（如果您使用g++或clang++）包含Eigen。无法使用我拥有的任何clang或gcc版本复制。您使用的是什么Egeng版本？什么编译标志？我使用的是Egeng 3.3.1和gcc 7.3.0。我还尝试了Egeng 3.3.5和3.3.7，得到了相同的消息。编译标志：-g-I/usr/local/include/Egen3-std=c++14