use of undeclared identifier 'temp' - c++

Question

The below c++ code gives me error use of undeclared identifier 'temp'
/home/test/include/memory.h
#ifndef MEMORY_H
#define MEMORY_H
#if __ENABLE_MEMORY
__device__ int temp = 50;
extern "C" inline __device__ void* memory(){
...
temp = temp + 100;
...
}
#endif
#endif
/home/test/include/internal_memory.h
#ifndef INTERNAL_MEMORY_H
#define INTERNAL_MEMORY_H
#ifndef __ENABLE_MEMORY
#define __ENABLE_MEMORY 1
#endif
#if __ENABLE_MEMORY
extern "C" __device__ void* memory();
static inline __device__ void* call_memory(){ return memory();}
#endif
#include <memory.h>
#endif
/home/test/main.cpp
#include "internal_memory.h"
..
.
.
void show(){
std::cout << "temp is: " << temp << std::endl;
}
.
.
.
I m compiling the code with clang++ version 11.0.0.
clang --version looks as follows:
clang version 11.0.0
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/rocm/llvm/bin
Im compiling the code as below.
/opt/rocm/llvm/bin/clang++ -DDEBUG -D__x86_64__ -I/home/test/include -I/home/test -g -fPIC -std=c++14 -o main.o -c main.cpp
what am i missing here.

Answer 1

Function memory has the __device__ qualifier (I suppose you are compiling a CUDA program).
memory refers to temp, which is a global variable in host memory. You probably want __device__ int temp = 50;
To query temp, you would need to copy its value back to the host. Along the lines of
int host;
cudaMemcpy(&host, &temp, sizeof(int), cudaMemcpyDeviceToHost);