# Function rustc_mir_dataflow::framework::direction::opt_clone_from_or_clone

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    fn opt_clone_from_or_clone<'a, T: Clone>(
        opt: &'a mut Option<T>,
        val: &T
    ) -> &'a mut T

Expand description

An analogue of `Option::get_or_insert_with` that stores a clone of `val` into `opt`, but uses the more efficient `clone_from` if `opt` was `Some`.

Returns a mutable reference to the new clone that resides in `opt`.