using c++ aggregate initialization in std::make_shared

You could create an adapter with a variadic constructor template to forward the arguments, something like:

template<class T>
struct aggregate_adapter : public T {
    template<class... Args>
    aggregate_adapter(Args&&... args) : T{ std::forward<Args>(args)... } {}
};

And then you can do:

auto foo = std::make_shared<aggregate_adapter<Foo>>("hello", 5, 'c');

Since aggregate_adapter<Foo> and Foo are related, foo is convertible to std::shared_ptr<Foo> as well.

Caveats

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Unfortunately, the use of forwarding also makes it impossible to brace-init any of the members like std::make_shared<aggregate_adapter<Foo>>({'h','e','l','l','o'}, 5, 'c'); without specifying the type explicitly, but the same restriction applies to make_shared already.