Java 17 / JDK 17: General Availability

Re:Java 17 / JDK 17: General Availability by zokier on Tuesday September 14, 2021 @10:54AM (#28525796)

> Kinda like Rust guarantees that Option<T> has the same size as T (aka free like in free beer).

That is not correct. Trivial counterexample:

https://play.rust-lang.org/?version=stable&mode=debug&editio...

prints

    4
    8

i.e. Option<T> is 4 bytes larger than plain T

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Re:Java 17 / JDK 17: General Availability by deepsun on Tuesday September 14, 2021 @11:30AM (#28526319)

Sure, I meant:

Rust guarantees to optimize the following types T such that Option<T> has the same size as T:

    Box<U>
    &U
    &mut U
    fn, extern "C" fn
    num::NonZero*
    ptr::NonNull<U>
    #[repr(transparent)] struct around one of the types in this list.

UPDATE: Or, better per your example: struct T {i: i32} takes the same size as i32: https://play.rust-lang.org/?version=stable&mode=debug&editio...

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