[DO NOT MERGE] debug_closure_helpers code size tweak

[hanna-kruppe]

WIP related to #149745

r? @ghost

[rust-log-analyzer]

The job tidy failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

fmt: checked 7156 files
tidy check
tidy [rustdoc_json (src)]: `rustdoc-json-types` modified, checking format version
tidy: Skipping binary file check, read-only filesystem
tidy [style (library)]: /checkout/library/core/src/fmt/builders.rs:71: undocumented unsafe
tidy [style (library)]: FAIL
removing old virtual environment
creating virtual environment at '/checkout/obj/build/venv' using 'python3.12' and 'venv'
Requirement already satisfied: pip in ./build/venv/lib/python3.12/site-packages (24.0)
Collecting pip
  Downloading pip-26.2.1-py3-none-any.whl.metadata (4.6 kB)
---
Running eslint on rustdoc JS files
info: ES-Check: checking 7 files...
info: ✓ ES-Check passed! All files are ES10 compatible.
typechecking javascript files
tidy: The following check failed: style (library)
Command `/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-tools-bin/rust-tidy --root-path=/checkout --cargo-path=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo --output-dir=/checkout/obj/build --concurrency=4 --npm-path=/node/bin/yarn --ci=true --extra-checks=py,cpp,js,spellcheck` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/tool.rs:1623:23
Executed at: src/bootstrap/src/core/build_steps/test.rs:1723:29

Command has failed. Rerun with -v to see more details.
Bootstrap failed while executing `test src/tools/tidy tidyselftest --extra-checks=py,cpp,js,spellcheck`
Currently active steps:
test::Tidy {  } at src/bootstrap/src/core/build_steps/test.rs:1641
Build completed unsuccessfully in 0:02:39
  local time: Sun Aug 16 17:14:54 UTC 2026