Rollup of 8 pull requests

[frewsxcv]

• Successful merges: rustbuild: Update bootstrap compiler #40524, Update docs for std::str #40682, Specialize Vec::from_iter for vec::IntoIter #40731, Document Cursor::new position is 0 #40783, Rustdoc: memoize pub use-reexported macros so they don't appear twice in docs #40814, store a copy of the Issue32230 info within TypeError #40836, Improve std::net docs #40838, Update various book modules #40864
• Failed merges: On-demandify the typechecking of item bodies #40540

[rust-highfive]

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

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[frewsxcv]

@bors r+ p=10

[bors]

📌 Commit 6785324 has been approved by frewsxcv

[bors]

⌛ Testing commit 6785324 with merge 4353cc1...

[bors]

💔 Test failed - status-travis