Tracking issue for release notes of #128443: Properly mark loop as diverging if it has no breaks

[rustbot]

This issue tracks the release notes text for #128443.

• Issue is nominated for the responsible team (and T-release nomination is removed).
• Proposed text is drafted by team responsible for underlying change.
• Issue is nominated for release team review of clarity for wider audience.
• Release team includes text in release notes/blog posts.

Release notes text:

The section title will be de-duplicated by the release team with other release notes issues.
Prefer to use the standard titles from previous releases.
More than one section can be included if needed.

# Compiler
- [The compiler now triggers the unreachable code warning properly for async functions that don't return/are `-> !`](https://github.com/rust-lang/rust/pull/128443)

Release blog section (if any, leave blank if no section is expected):

[compiler-errors]

LGTM 👍