Is this a valid way to guarantee thread_local initialisation? [duplicate]

Consider the below testcase:

#include <iostream> #include <thread> thread_local struct Bar { Bar() { std::cout << '*' << std::endl; } ~Bar() { std::cout << '~' << std::endl; } } bar; struct Foo { void baz() { (void)&bar; } }; int main() { Foo f; f.baz(); std::thread t(&Foo::baz, &f); t.join(); } 

On Coliru it works as I intend, with the seemingly useless statement (void)&bar apparently counting as "use" and ensuring that bar is constructed in any thread that invokes baz().

Is this guaranteed, or should I do something more?

I'm hoping to use a class like Bar to wrap some per-thread initialisation required by a C library I'm going to use, with a minimum of boilerplate. baz() is already a function that any thread will call to do work with the C library, so this could effectively be a transparent solution.