Good Idea: safe way to transmute `Vec<Option<&Foo>>` to `Vec<&Foo>`

[Lokathor]

https://www.reddit.com/r/rust/comments/1ez6f2c/any_safe_way_to_transmute_vecoptionfoo_to_vecfoo/

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So yeah, what we want is to be able to convert from Option<&i32> to &i32, particularly within a vec/slice/container.

There's lots of types with guaranteed option representation, so we probably want to use some sort of trait.

[fu5ha]

Isn't this only possible going from &[&Foo] to &[Option<&Foo>] and not the other way around? Or do you mean that in the owned Vec case, we should check all values are Some before doing the transmute?

[Lokathor]

The latter case, we'd do a check then convert if it's valid.