c++ - CUDA 错误 : name followed by "::" must be a class or namespace

Question

我正在处理我的第一个 CUDA 程序并使用 nvcc 编译器遇到错误，如果我使用 g++ 编译则不会遇到这种错误。

我的代码:

#include <iostream>
#include <cmath>

using namespace std;

double distance(double first, double second);

int main(){
   double dis;
   dis = distance(7.0, 1.0);
   cout << "distance = " << dis << endl;
   return 0;
}

double distance(double first, double second){
   double diff;
   diff = abs(first-second);
   return diff;
}

如果我用nvcc test.cu -o test编译，结果是:

/usr/include/c++/5/bits/stl_iterator_base_types.h(168): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

/usr/include/c++/5/bits/stl_iterator_base_types.h(169): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

/usr/include/c++/5/bits/stl_iterator_base_types.h(170): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

/usr/include/c++/5/bits/stl_iterator_base_types.h(171): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

/usr/include/c++/5/bits/stl_iterator_base_types.h(172): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

当我将文件扩展名更改为.cpp 并按如下方式编译时，g++ test.cpp -o test，代码符合要求。如果我然后执行 ./test，我会得到我正在寻找的结果:

distance = 6

查看this帖子启发我考虑我从主机/设备划分的错误一侧调用某些东西的可能性，但是，我还没有进行任何 GPU 调用。

不确定发生了什么，但到目前为止，CUDA 编译器似乎非常挑剔。

Answer 1

您需要将 -std=c++11 选项添加到 nvcc 来编译它。通过使用 std 命名空间，您将与 std::distance 发生冲突，后者需要 c++11 或更高版本才能使用 nvcc 进行编译。

这个有效:

$ cat bugaboo.cu
#include <iostream>
#include <cmath>

using namespace std;

double distance(double first, double second);

int main(){
   double dis;
   dis = distance(7.0, 1.0);
   cout << "distance = " << dis << endl;
   return 0;
}

double distance(double first, double second){
   double diff;
   diff = abs(first-second);
   return diff;
}

$ nvcc --version
nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2018 NVIDIA Corporation
Built on Tue_Jun_12_23:07:04_CDT_2018
Cuda compilation tools, release 9.2, V9.2.148

$ nvcc --std=c++11 -o bugaboo bugaboo.cu

$ ./bugaboo
distance = 6

这不是:

$ nvcc -o bugaboo bugaboo.cu
/usr/include/c++/4.8/bits/stl_iterator_base_types.h(165): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(165): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(165): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(166): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(166): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(166): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(167): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(167): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(167): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(168): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(168): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(168): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(169): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(169): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(169): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

15 errors detected in the compilation of "/tmp/tmpxft_00000acd_00000000-8_bugaboo.cpp1.ii".