Use “.cu” as file extension name when playing Thrust

Today, I tried the simple Thrust program:

$ cat a.c
#include <thrust/host_vector.h>
#include <thrust/device_vector.h>
#include <iostream>

int main(void) {
        // H has storage for 4 integers
        thrust::host_vector<int> H(4);

        // initialize individual elements
        H[0] = 14;
        H[1] = 20;
        H[2] = 38;
        H[3] = 46;

        // H.size() returns the size of vector H
        std::cout << "H has size " << H.size() << std::endl;

        // print contents of H
        for(int i = 0; i < H.size(); i++)
                std::cout << "H[" << i << "] = " << H[i] << std::endl;

        // resize H
        H.resize(2);
        std::cout << "H now has size " << H.size() << std::endl;

        // Copy host_vector H to device_vector D
        thrust::device_vector<int> D = H;

        // elements of D can be modified
        D[0] = 99;
        D[1] = 88;

        // print contents of D
        for(int i = 0; i < D.size(); i++)
                std::cout << "D[" << i << "] = " << D[i] << std::endl;

        // H and D are automatically deleted when the function returns
        return 0;
}

Built it:

$ nvcc -arch=sm_37 a.c
In file included from a.c:1:0:
/opt/cuda/bin/..//include/thrust/host_vector.h:25:18: fatal error: memory: No such file or directory
compilation terminated.

It seemed very weird! After scanning Thrust’s FAQ, I came across the following tip:

Make sure that files that #include Thrust have a .cu extension. Other extensions (e.g., .cpp) will cause nvcc to treat the file incorrectly and produce an error message.

Renamed the source file name and rebuilt it:

$ mv a.c a.cu
$ nvcc -arch=sm_37 a.cu
$ ./a.out
H has size 4
H[0] = 14
H[1] = 20
H[2] = 38
H[3] = 46
H now has size 2
D[0] = 99
D[1] = 88

Worked like a charm!