Detect overflow in proc_macro_server subspan

[tmiasko]

• Detect overflow in proc_macro_server subspan
• Add tests for overflow in Vec::drain
• Add tests for overflow in String / VecDeque operations using ranges

[rust-highfive]

r? @sfackler

(rust_highfive has picked a reviewer for you, use r? to override)

[bors]

☔ The latest upstream changes (presumably #74862) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #70793) made this pull request unmergeable. Please resolve the merge conflicts.

[tmiasko]

r? @Mark-Simulacrum

[Mark-Simulacrum]

@estebank -- I note that the issue suggested that we were unsure about the DWIM semantics you meant (#72237 (comment)).

That said this has been open for a month now and looks reasonable to me; if there are semantics that move us from panicking to not panicking I think that'd relatively (if not perfectly) backwards compatible to move to. I am going to approve it, but we can revert or otherwise pause if necessary.

@bors r+

[bors]

📌 Commit e7b0bb0056c268cce0682b99beaf4e2979745245 has been approved by Mark-Simulacrum

[bors]

🔒 Merge conflict

This pull request and the master branch diverged in a way that cannot be automatically merged. Please rebase on top of the latest master branch, and let the reviewer approve again.

How do I rebase?

Assuming self is your fork and upstream is this repository, you can resolve the conflict following these steps:

1. git checkout range-overflow (switch to your branch)
2. git fetch upstream master (retrieve the latest master)
3. git rebase upstream/master -p (rebase on top of it)
4. Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
5. git push self range-overflow --force-with-lease (update this PR)

You may also read Git Rebasing to Resolve Conflicts by Drew Blessing for a short tutorial.

Please avoid the "Resolve conflicts" button on GitHub. It uses git merge instead of git rebase which makes the PR commit history more difficult to read.

Sometimes step 4 will complete without asking for resolution. This is usually due to difference between how Cargo.lock conflict is handled during merge and rebase. This is normal, and you should still perform step 5 to update this PR.

Error message

Auto-merging library/alloc/src/vec.rs
CONFLICT (content): Merge conflict in library/alloc/src/vec.rs
Auto-merging library/alloc/src/string.rs
CONFLICT (content): Merge conflict in library/alloc/src/string.rs
Auto-merging library/alloc/src/collections/vec_deque.rs
CONFLICT (content): Merge conflict in library/alloc/src/collections/vec_deque.rs
Automatic merge failed; fix conflicts and then commit the result.

[bors]

☔ The latest upstream changes (presumably #75207) made this pull request unmergeable. Please resolve the merge conflicts.

[tmiasko]

The #75207 introduced a new bounds checking API for ranges, and used it to fix
most of overflow issues, making most of changes here unnecessary. It didn't add
any new tests, so I retained those.

[tmiasko]

@rustbot modify labels: +S-waiting-on-review -S-waiting-on-author

[Mark-Simulacrum]

@bors r+

[bors]

📌 Commit f8cfb2f has been approved by Mark-Simulacrum

[bors]

⌛ Testing commit f8cfb2f with merge f4e4485...