7897ee4d42
improve error message shown for unsafe operations Add a short explanation saying why undefined behavior could arise. In particular, the error many people got for "creating a pointer to a packed field requires unsafe block" was not worded great -- it lead to people just adding the unsafe block without considering if what they are doing follows the rules. I am not sure if a "note" is the right thing, but that was the easiest thing to add... Inspired by @gnzlbg at https://github.com/rust-lang/rust/issues/46043#issuecomment-381544673