Fix std::convert::TryFrom doc

[tae-soo-kim]

Original text:

truncating the i64 to an i32 (essentially giving the i64’s value modulo i32::MAX)

This can't be true, because i32::MAX is an odd number. The correct value seems (i32::MAX + 1) * 2, but this is complicated and distracting, and I suggest removing the parentheses entirely.

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @scottmcm (or someone else) soon.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

• @rustbot author: the review is finished, PR author should check the comments and take action accordingly
• @rustbot review: the author is ready for a review, this PR will be queued again in the reviewer's queue

[scottmcm]

Thanks for the PR! Agreed that modulo i32::MAX just doesn't make sense, so let's take this improvement as-is.
@bors r+ rollup

@tae-soo-kim, would you be interested in also doing a follow-up PR to improve the paragraph more broadly? The From trait recently got some new docs about what it should do (https://doc.rust-lang.org/nightly/std/convert/trait.From.html#when-to-implement-from), and that might inspire some similar for TryFrom. For example, successful TryFrom conversions should probably also be "value-preserving", so returning a modular result for integer-to-integer conversions would be a poor choice.

[bors]

📌 Commit e15e9a6 has been approved by scottmcm

It is now in the queue for this repository.

[tae-soo-kim]

would you be interested in also doing a follow-up PR to improve the paragraph more broadly?

I guess no at this time. I'm still a beginner learning this language, worrying my understanding of it could be imprecise and misleading. But if you write something that I see obviously wrong, I'm happy to file a bug report.