Is using `std::get` on a `std::tuple` guaranteed to be thread-safe for different values of `I`?

Answer 1

The short answer is that it depends on the types and what does process do instead of get. By itself, get merely retrieve the address of the object and return it as a reference. Retrieving the address is mostly just reading the contents of integers. It does not raise race conditions. Roughly speaking, the code snippet in your question is thread-safe if and only if the following is thread-safe,

T1 t1;
T2 t2;
T3 t3;

std::thread{[&]{process(t1);}}.detach();
std::thread{[&]{process(t2);}}.detach();
std::thread{[&]{process(t3);}}.detach();