add a panic example to std::from_utf8_unchecked #35890
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| /// | ||
| /// Incorrect bytes: | ||
| /// | ||
| /// ``` |
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This should probably be no_run, right?
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Actually, this example won't panic, so I guess it won't.
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Actually it might? The from_utf8_unchecked won't fail, but printing it might? Not sure.
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This example won't panic?
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From what I understand, this function should never panic (hence it being "unchecked").
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unchecked means it won't return an Err. It won't panic either, but the call to println! will, as it attempts to print an invalid string. I'll split the lines out to make that clearer.
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Whoops, never mind. It won't panic there either.
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While I can't think of any specific examples right now, it'd be great if we could somehow demonstrate memory safety issues, as described in the "Safety" section of this function. |
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@frewsxcv Yeah, I can't think of any examples either. If somebody reading this knows of one, can you let me know? Thanks in advance! |
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@ubsan ping! |
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@matthew-piziak There are no memory safety issues with the current runtime. Someone could write something assuming valid utf-8, however, and read right off the end, however, for example with a |
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@ubsan Gotcha, thanks. What do you think of this PR as-is, then? |
| /// use std::str; | ||
| /// | ||
| /// // some invalid bytes, in a vector | ||
| /// let sparkle_heart = vec![0, 159, 146, 150]; |
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maybe change this name, since it's no longer a sparkle heart?
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Done. I also renamed the example in the checked conversion.
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@matthew-piziak I don't generally recommend committing UB in documentation, no matter how frivolous I may think that UB is :P. I'm not sure... You could say "poses a safety issue" as well. |
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@ubsan Even with |
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@matthew-piziak I meant more of "don't show people UB in documentation". I'd rather use correct examples. |
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@ubsan That's fair. Shall we close this PR? |
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Yes, I agree. Thanks @matthew-piziak ! |
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Decided not to show undefined behavior in documentation. |
Show that passing invalid bytes to
str::from_utf8_uncheckedis a runtime panic.r? @steveklabnik