Add a note about overflowing in the RangeFrom iterator
#32592
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The idea came from reddit: https://www.reddit.com/r/rust/comments/4cfea1/i_dont_understand_why_this_for_loop_is_giving_me/. |
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I'm not sure adding a note like this is the best solution (which would be to fix the issue :p). |
| @@ -1539,6 +1539,10 @@ impl<Idx: PartialOrd<Idx>> Range<Idx> { | |||
| /// | |||
| /// See the [`contains()`](#method.contains) method for its characterization. | |||
| /// | |||
| /// Note: No overflow checking is done for the iterator implementation; if you | |||
| /// use an integer range and the integer overflows, it will panic in debug mode | |||
| /// and create an endless loop in release mode. | |||
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Perhaps the wording can be tweaked here slightly along the lines of:
- It will likely panic in debug mode, but isn't necessarily guaranteed to do so at this time.
- This will only create an endless loop for the range
0.., right? Something like1..will overflow to 0 at some point which should stop iteration?
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No, it's always an endless loop (if it doesn't panic), the implementation does not have a path that returns None: https://github.com/tbu-/rust/blob/ad9f9a563ed82df5ea82bc32497dd986614bdee7/src/libcore/iter.rs#L4642-L4654.
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Ah right. I guess I'm basically thinking we want to word this in such a way so that we're not committing to anything, just noting the current behavior.
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@alexcrichton Reworded the note a bit. Is that fine? |
Add a note about overflowing in the `RangeFrom` iterator
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