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@ -15,14 +15,18 @@ boggling.
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is going to cause arbitrary chaos that can't really be predicted. Do not
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is going to cause arbitrary chaos that can't really be predicted. Do not
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transmute `3` to `bool`. Even if you never *do* anything with the `bool`. Just
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transmute `3` to `bool`. Even if you never *do* anything with the `bool`. Just
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don't.
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don't.
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* Transmute has an overloaded return type. If you do not specify the return type
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* Transmute has an overloaded return type. If you do not specify the return type
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it may produce a surprising type to satisfy inference.
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it may produce a surprising type to satisfy inference.
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* Transmuting an & to &mut is UB.
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* Transmuting an & to &mut is *always* UB.
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* Transmuting an `&` to `&mut` is UB.
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* Transmuting an `&` to `&mut` is *always* UB.
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* No you can't do it.
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* No you can't do it.
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* No you're not special.
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* No you're not special.
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* Transmuting to a reference without an explicitly provided lifetime
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* Transmuting to a reference without an explicitly provided lifetime
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produces an [unbounded lifetime]
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produces an [unbounded lifetime].
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* When transmuting between different compound types, you have to make sure they
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* When transmuting between different compound types, you have to make sure they
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are laid out the same way! If layouts differ, the wrong fields are going to
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are laid out the same way! If layouts differ, the wrong fields are going to
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get filled with the wrong data, which will make you unhappy and can also be UB
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get filled with the wrong data, which will make you unhappy and can also be UB
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@ -47,7 +51,7 @@ pointer casts or `union`s, but without any of the lints or other basic sanity
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checks. Raw pointer casts and `union`s do not magically avoid the above rules.
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checks. Raw pointer casts and `union`s do not magically avoid the above rules.
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[unbounded lifetime]: unbounded-lifetimes.html
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[unbounded lifetime]: ./unbounded-lifetimes.md
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[transmute]: ../std/mem/fn.transmute.html
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[transmute]: ../std/mem/fn.transmute.html
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[transmute_copy]: ../std/mem/fn.transmute_copy.html
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[transmute_copy]: ../std/mem/fn.transmute_copy.html
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[ucg-layout]: https://rust-lang.github.io/unsafe-code-guidelines/layout.html
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[ucg-layout]: https://rust-lang.github.io/unsafe-code-guidelines/layout.html
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