What is std::declval () used for?

To construct an object of type T with default arguments so it can be passed to a function at runtime

To convert an existing object to type T using static_cast in an evaluated expression context

To declare a variable of type T inside a function body without calling its constructor first

To obtain an rvalue reference of type T in unevaluated contexts without constructing the object

Multiple ChoiceIntermediate 45s

How std::declval may be used in unevaluated context

What is std::declval<T>() used for?

Options

1To construct an object of type T with default arguments so it can be passed to a function at runtime
2To convert an existing object to type T using static_cast in an evaluated expression context
3To declare a variable of type T inside a function body without calling its constructor first
4To obtain an rvalue reference of type T in unevaluated contexts without constructing the object

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