ref: narrow unused lint expectations in sentry-core hub

[szokeasaurusrex]

Remove the blanket #![allow(unused)] in sentry-core/src/hub.rs. This will allow the linter to find problems like the following (from #1073) and many more, rather than needing to rely on the clanker for such things.

Instead, we now have a macro that adds a let _ = ...arguments... when the client feature is enabled. This solves the stated purpose of having the allow(unused) in the first place, but where more narrowly.

The clanker also cleaned up some truly unused things that were suppressed before.

🤖What the clanker wrote

Description

Removes the blanket #![allow(unused)] from sentry-core/src/hub.rs.

Instead of repeating a long #[cfg_attr(not(feature = "client"), expect(unused, ...))] annotation across many parameters, this change uses a small documented local use_without_client! helper macro that only touches those values in not(feature = "client") builds. That keeps the handling narrow to the specific methods and arguments that need it, while avoiding duplicated attributes in the signatures.

Also cleans up truly unused imports, removes an unnecessary mut in the release-health session setup path, and keeps the file rustfmt-clean for CI.

Validated with:

• cargo +1.88.0 fmt --all --check
• cargo +1.88.0 clippy -p sentry-core --no-default-features -- -D warnings
• cargo +1.88.0 clippy -p sentry-core --no-default-features --features client -- -D warnings
• cargo +1.88.0 clippy -p sentry-core --all-features -- -D warnings
• cargo +1.88.0 clippy -p sentry-core --no-default-features --features release-health -- -D warnings
• cargo +1.88.0 clippy -p sentry-core --no-default-features --features logs -- -D warnings

Note: a full local workspace cargo clippy --all-features --workspace --tests --examples --locked is blocked in this environment by missing system OpenSSL development libraries, which is unrelated to this hub.rs change.

Issues

• N/A

Reminders

• GH Issue ID / Linear ID: N/A
• CHANGELOG.md: not updated (internal lint cleanup)
• PR title uses conventional commit style
• Useful links for external contributors: Sentry SDK development docs, Discord community

  

[szokeasaurusrex]

clanker came up with this idea, pretty nice. thanks GPT-5.4