Fun with lifetimes

foobar.cpp

#include <iostream>
#include <vector>

struct Foo {
  float x;
  float y;
  float z;
};
using Bar = std::vector<float>;

Foo MakeFoo();
Bar MakeBar();
std::ostream &operator<<(std::ostream &os, Foo const &data);
std::ostream &operator<<(std::ostream &os, Bar const &data);

template <typename T> class View {
public:
  explicit View(T const &data) : ref_{data} {}
  T const &GetRef() const { return ref_; }

private:
  T const &ref_;
};

Foo MakeFoo() { return Foo{1.0F, 2.0F, 3.0F}; }
Bar MakeBar() { return Bar{1.0F, 2.0F, 3.0F}; }

std::ostream &operator<<(std::ostream &os, Foo const &data) {
  os << "x: " << data.x << ", y: " << data.y << ", z: " << data.z;
  return os;
}
std::ostream &operator<<(std::ostream &os, Bar const &data) {
  for (auto const &x : data) {
    os << x << " ";
  }
  return os;
}

int main() {
  // Correct:
  // const Foo foo{MakeFoo()};
  // View<Foo> foo_view{foo};
  View<Foo> foo_view{MakeFoo()};
  std::cout << foo_view.GetRef() << std::endl;
  // Correct:
  // const Bar bar{MakeBar()};
  // View<Bar> bar_view{bar};
  View<Bar> bar_view{MakeBar()};
  std::cout << bar_view.GetRef() << std::endl;
  return 0;
}

Compile and run with:

$ clang++-10 -std=c++14 foobar.cpp -Werror -Weverything -Wno-c++98-compat -O3 -g -fsanitize=address -fsanitize-address-use-after-scope -fsanitize-recover=address && ASAN_OPTIONS=halt_on_error=0 ./a.out

Play around with different opt levels.