Why can `str::from_utf8_unchecked(&self.vec)` work in std

Asked Apr 12 '22 at 14:15

Active Apr 12 '22 at 14:15

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I want to find out how Borrow works on String from the source code which is implemented by Index<RangeFull> (source code).

It uses str::from_utf8_unchecked(&self.vec). Here is the problem. str::from_utf8_unchecked accepts &[u8] as its argument but &String.vec is a struct defined here. Why can it work? Unsafe? How does unsafe do this?

asked Apr 12 '22 at 14:15

Vonfry

1

Thanks to deref coercion, the `&Vec` becomes a `&[u8]` (through [this `Deref` implementation](https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#impl-Deref)). – E_net4 - Krabbe mit Hüten Apr 12 '22 at 14:33

Why can `str::from_utf8_unchecked(&self.vec)` work in std

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