Rust 1.54.0
a178d0322

# Unsized Types

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> Sometimes referred to as ‘DSTs’ or ‘unsized types’, these types let us talk about types whose size we can only know at runtime. The `Sized` trait is automatically implemented for everything the compiler knows the size of at compile time. A trait bound on `?Sized` is the opposite of a trait bound on `Sized`; that is, we would read this as “`T` may or may not be `Sized`”.

ⓘ

    fn generic<T: ?Sized>(t: &T) {
        // ...snip...
    }

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