Calling a purely template lambda callback in C++20 [duplicate]

Question

With C++20, we've gained templated lambdas, great!

[]<class T>(){};

Is it possible to call a lambda callback with a template parameter, but no argument to deduce it from?

For ex,

template <class Func>
void do_it(Func&& func) {
    // Call lambda with template here, but don't provide extra arguments.
    // func<int>(); ?
}

do_it([]<class T>(){ /* do something with T */ });

Answer 1

Is it possible to call a lambda callback with a template parameter, but no argument to deduce it from?

This is probably what you want

template <class Func>
void do_it(Func&& func) {
  func.template operator()<int>();
}