refactor(allocator): fix manual_div_ceil clippy warnings

[overlookmotel]

Continuation of #21210.

[overlookmotel]

• docs(allocator): add doc comments for panics and errors #21230
• refactor(allocator): fix unnecessary_safety_comment clippy warnings #21229
• refactor(allocator): fix unsafe_op_in_unsafe_fn clippy warnings #21228
• refactor(allocator): fix mut_from_ref clippy warnings #21225
• refactor(allocator): fix cast_sign_loss clippy warnings #21224
• refactor(allocator): fix cast_ptr_alignment clippy warnings #21223
• refactor(allocator): fix ptr_cast_constness clippy warnings #21222
• refactor(allocator): fix ptr_as_ptr clippy warnings #21221
• refactor(allocator): fix ref_as_ptr clippy warnings #21220
• refactor(allocator): fix borrow_as_ptr clippy warnings #21219
• refactor(allocator): fix unused_self clippy warnings #21218
• refactor(allocator): fix manual_div_ceil clippy warnings #21217 👈 (View in Graphite)
• refactor(allocator): fix map_unwrap_or clippy warnings #21216
• refactor(allocator): fix filter_map_next clippy warnings #21215
• refactor(allocator): fix single_match_else clippy warnings #21214
• refactor(allocator): fix inconsistent_struct_constructor clippy warnings #21213
• refactor(allocator): fix semicolon_if_nothing_returned clippy warnings #21212
• refactor(allocator): fix uninlined_format_args clippy warnings #21211
• refactor(allocator): fix lifetimes clippy warnings #21210
• main

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[codspeed-hq]

Merging this PR will not alter performance

✅ 48 untouched benchmarks
⏩ 3 skipped benchmarks¹

---

_{Comparing om/04-08-refactor_allocator_fix_manual_div_ceil_clippy_warnings (a9cfc37) with om/04-08-refactor_allocator_fix_map_unwrap_or_clippy_warnings (7a99bc3)}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Copilot]

Pull request overview

Updates the arena allocator’s Bump::shrink logic to use the standard div_ceil API, addressing the clippy::manual_div_ceil lint and allowing removal of the corresponding #[expect] entry as part of the ongoing bumpalo-derived code cleanup.

Changes:

• Replace (old_size + 1) / 2 with old_size.div_ceil(2) in the shrink non-overlap threshold.
• Update the accompanying comment to match the new expression.
• Remove clippy::manual_div_ceil from the file-level #![expect(...)] list.

[graphite-app]

Merge activity

• Apr 9, 8:43 AM UTC: overlookmotel added this pull request to the Graphite merge queue.
• Apr 9, 9:07 AM UTC: Merged by the Graphite merge queue.