Insert into an unordered_set failed - c++

Question

First of all, this is NOT my own code! It's taken from Google's Android sourcecode https://android.googlesource.com/platform/art/+/android-9.0.0_r10/tools/hiddenapi/hiddenapi.cc
So, it should be tested and should work! But, it fails at the point "insert..."
Short code:
/*...*/
std::unordered_set<std::string> light_greylist_;
/*...*/
/*Caller:*/ OpenApiFile(light_greylist_path_, &light_greylist_);
bool OpenApiFile(const std::string& path, std::unordered_set<std::string>* list) {
std::ifstream api_file(path, std::ifstream::in);
for (std::string line; std::getline(api_file, line);) {
/* line IS filled; I've checked it with a simple fprintf(): [this IS my code for testing]*/
FILE *stream = fopen("test.txt", "a+");
fprintf(stream, "%s\n", line.c_str());
fclose(stream);
/* This is the point where it crashes with an "Illegal instruction (core dumped)"*/
list->insert(line);
}
api_file.close();
return true;
}
What goes wrong?

Answer 1

I'd make list a reference instead of a pointer. It's hard to say why the original code uses pointers since it'll most probably crash if called with NULL. Also check that the file has been successfully opened (even though it seems to have succeeded for you this time).
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <unordered_set>
bool OpenApiFile(const std::string& path, std::unordered_set<std::string>& list) {
std::ifstream api_file(path, std::ifstream::in);
if (!api_file) {
return false;
}
for (std::string line; std::getline(api_file, line);) {
list.insert(line);
}
return true;
}
int main(int argc, char* argv[]) {
std::vector<std::string> files(argv+1, argv+argc);
for(auto& light_greylist_path_ : files) {
std::unordered_set<std::string> light_greylist_;
if (OpenApiFile(light_greylist_path_, light_greylist_) == false) {
std::cerr << "failed opening "+light_greylist_path_+"\n";
} else {
for(auto& lg : light_greylist_) {
std::cout << lg << "\n";
}
}
}
return 0;
}