ci: allow the non-local variant of the semicolon-in-expressions lint in u256

[gustavovalverde]

Motivation

The Book workflow has been red on every push to main since 2026-07-27, and the weekly Advisory Checks workflow fails the same way. Both build docs on nightly with -D warnings, and zebra-chain no longer compiles under it:

error: trailing semicolon in macro used in expression position
  --> zebra-chain/src/work/u256.rs:13:1
   = note: `-D semicolon-in-expressions-from-non-local-macros` implied by `-D warnings`

No Zebra change caused this. rustc split semicolon_in_expressions_from_macros into two lints, by where the macro is defined:

lint	default	covers
semicolon_in_expressions_from_macros	deny	macros defined in this crate
semicolon_in_expressions_from_non_local_macros	warn	macros from other crates

uint::construct_uint! comes from an external crate, so it moved out from under the existing allow and into a lint nothing was silencing. uint 0.10.0 is the latest release, so no upstream version fixes the expansion.

This is a hotfix for red main, so it has no prior issue.

Solution

Allow both lint names in u256.rs, together with unknown_lints.

All three are required. Only nightly knows the new name, so naming it directly makes stable emit unknown_lints, which is warn-by-default and therefore fatal under clippy's -D warnings.

A single #![allow(future_incompatible)] would have covered both names and survived any future split, but rustc rejects it here: allow(future_incompatible) is ignored unless specified at crate level, and crate level is far too broad.

Tests

Checked against the three toolchains CI uses:

variant	nightly 1.99	stable 1.97	stable 1.91 (MSRV)
before this change	fail	pass	pass
both names, without unknown_lints	pass	fail	fail
this change	pass	pass	pass

• The verbatim book.yml docs command (cargo doc --no-deps --workspace --all-features --document-private-items under the full CI RUSTDOCFLAGS) exits 0 on nightly 1.99.0.
• cargo clippy -p zebra-chain --all-features --all-targets -- -D warnings is clean on stable.
• cargo test -p zebra-chain --lib work:: passes, 43 tests.

Specifications & References

• Tracking Issue for denying trailing semicolons in expression macro bodies rust-lang/rust#79813
• Same lint, previous occurrence: fix(ci): silence semicolon-in-expressions-from-macros in u256 #10986

Follow-up Work

book.yml and advisory.yml pair an unpinned nightly toolchain with -D warnings, so any rustc lint addition or split turns main red. This is the second occurrence in ten days. Pinning the nightly is a trade-off worth its own discussion.

book.yml also points readers to lint.yml:jobs.docs, which no longer exists.

AI Disclosure

• AI tools were used: Claude Code for the root cause analysis, the toolchain test matrix, and this description.

PR Checklist

• The PR title follows conventional commits format: type(scope): description
• The PR follows the contribution guidelines.
• This change was discussed in an issue or with the team beforehand.
• The solution is tested.
• The documentation and changelogs are up to date. CI-only fix with no user-visible change, matching fix(ci): silence semicolon-in-expressions-from-macros in u256 #10986.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-07-28 18:37 UTC · Rule: batched · triggered by rule move to any queue if GitHub Rulesets are satisfied
• ✅ Checks skipped · PR is already up-to-date
• ✅ Merged — 2026-07-28 18:38 UTC · at 3bab53b6aff9b10048c82f42e6a5f75822833502 · merge

This pull request spent 46 seconds in the queue, including 9 seconds running CI.

Required conditions to merge

• #review-threads-unresolved = 0 [🛡 GitHub repository ruleset rule PR Requirements]
  • ci: allow the non-local variant of the semicolon-in-expressions lint in u256 #11131
• github-review-approved [🛡 GitHub branch protection]
  • ci: allow the non-local variant of the semicolon-in-expressions lint in u256 #11131
• github-review-approved [🛡 GitHub repository ruleset rule PR Requirements]
  • ci: allow the non-local variant of the semicolon-in-expressions lint in u256 #11131
• any of [🛡 GitHub repository ruleset rule PR Requirements]:
  • check-success = @github-actions/lint
  • check-neutral = @github-actions/lint
  • check-skipped = @github-actions/lint
• any of [🛡 GitHub repository ruleset rule PR Requirements]:
  • check-success = test-crates
  • check-neutral = test-crates
  • check-skipped = test-crates
• any of [🛡 GitHub repository ruleset rule PR Requirements]:
  • check-success = unit-tests
  • check-neutral = unit-tests
  • check-skipped = unit-tests