fix(core): move newer bail! sites out of expression position (partial #2835, complements #2843)

[phil-opp]

Summary

Part of #2835. Complements the pre-existing #2843 — please land both.

eyre::bail! / bail! expand to a block ending in a semicolon ({ return Err(..); }). Used as the tail expression of a block or as a bare match arm, that trailing semicolon is in expression position, which trips semicolon_in_expressions_from_macros / semicolon_in_expressions_from_non_local_macros — denied under future_incompatible on recent nightlies, failing dora-core compilation.

Relationship to #2843

#2843 (opened 2026-07-26, Closes #2835) fixes this lint class across the whole workspace (48 files: node API, CLI, etc.). Since then, newer code has merged into main that introduced additional expression-position bail! sites in dora-core which #2843 does not cover. This PR fixes those.

The two PRs are disjoint — no overlapping files — so both can land independently, and dora-core is only fully clean once both do:

dora-core file	fixed by
build/git.rs, descriptor/mod.rs, descriptor/validate.rs, descriptor/expand.rs	this PR
topics.rs, build/mod.rs	#2843

What changed here

Moved every affected call in the files above to statement position:

• Block-tail calls ({ …; bail!(..) }): added a trailing ;.
• Bare match arms (_ => bail!(..)): wrapped in a { bail!(..); } block.

18 sites total. Every one diverges (bail! returns early), so it still coerces to the surrounding arm/expression type via the never type — no runtime behavior change.

Verification

Toolchain: rustc 1.99.0-nightly (771916f90 2026-08-08).

• cargo +nightly check -p dora-core — the 13 diagnostics that were reported at these sites are gone. (Note: which sites a given nightly flags for the non-local eyre::bail! variant varies by toolchain build; the topics.rs / build/mod.rs sites owned by fix: avoid bail macros in expression position #2843 are the remaining ones needed for full cross-toolchain coverage.)
• cargo +1.97.1 check -p dora-core — clean on the pinned toolchain.
• cargo +1.97.1 clippy -p dora-core -- -D warnings — clean.
• cargo +1.97.1 fmt -p dora-core -- --check — clean.
• cargo +1.97.1 test -p dora-core — 272 passing.

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[phil-opp]

🤖 Automated review by Claude — this is a fully automated review with no human in the loop.

I reviewed this diff and found no issues. The changes are mechanical: adding a trailing ; to block-tail bail! / eyre::bail! calls and wrapping bare match-arm bail! calls in { …; } blocks across libraries/core/src/build/git.rs, descriptor/expand.rs, descriptor/mod.rs, and descriptor/validate.rs. Every touched call diverges (early return), so it still coerces to the surrounding arm/expression type and runtime behavior is unchanged — the change only silences the semicolon_in_expressions_from_macros nightly lint.

One thing worth flagging for the maintainer: this overlaps with the still-open #2843 ("avoid bail macros in expression position"), which applies the same fix more broadly. You may want to reconcile the two so the lint fix lands once.

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[phil-opp]

Update: eyre-rs/eyre#294 was merged and a PR to do a new release is up: eyre-rs/eyre#296

[phil-opp]

The 18 edited sites are all correct — every one diverges, so !-coercion keeps them type-checking and there is no runtime change.

One correction to the body: it states that cargo +nightly check -p dora-core has no remaining trailing semicolon in macro diagnostics. That is not the case. Two expression-position sites survive in dora-core: libraries/core/src/topics.rs:486 (Err(VarError::NotUnicode(_)) => eyre::bail!(...), a bare match arm) and libraries/core/src/build/mod.rs:277 (block-tail eyre::bail! in the else of validate_subdir). Both are covered by #2843.

So this PR alone does not unblock the nightly build of dora-core — it does so only once #2843 lands too. Worth either correcting the body or merging the two as a pair. (They are otherwise disjoint: no file overlap, so both should land.)

[phil-opp]

Thanks — you're right, and I've corrected the body.

Confirmed against the current tree: within dora-core, #2843 touches only topics.rs and build/mod.rs, and this PR touches only build/git.rs + the descriptor/{mod,validate,expand}.rs sites — no file overlap, so the two are complementary. My PR covers the expression-position bail! sites in code that merged into main after #2843 was opened; dora-core is fully nightly-clean only once both land. The title/body now scope the claim to a partial fix rather than a standalone unblock.

(On rustc 1.99.0-nightly (771916f90 2026-08-08) I don't reproduce the diagnostic at the two #2843 sites, whereas #2843 was validated on da86f4d07 2026-07-24 — the non-local eyre::bail! variant seems to be flagged inconsistently across nightly builds. Landing both makes the crate robust regardless of which nightly a contributor runs.)

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Generated by Claude Code

[phil-opp]

Heads up — this may no longer be needed. eyre 0.6.14 has been released, and it removes the trailing semicolon from every arm of the bail! macro:

 macro_rules! bail {
     ($msg:literal $(,)?) => {
-        return $crate::private::Err($crate::eyre!($msg));
+        return $crate::private::Err($crate::eyre!($msg))
     };
     …
 }

That semicolon was the entire cause of the lint, so both shapes this PR rewrites — block-tail calls and bare match arms — are fine as-is under 0.6.14.

I opened #3126, a one-package Cargo.lock bump with no source changes. On rustc 1.99.0-nightly (12c36e253 2026-08-10), cargo +nightly check --all (excluding the PyO3 crates) drops from 154 trailing semicolon in macro used in expression position diagnostics across 17 crates to 0, which subsumes both this PR's 4 dora-core files and #2843's 48.

Worth noting your observation here — that which sites a given nightly flags for the non-local eyre::bail! variant varies by toolchain build — held up in testing: on the nightly above the diagnostics surface as future-incompat warnings rather than the hard errors reported in #2835. That variability is a good argument for fixing it at the dependency rather than chasing call sites per toolchain.

Deferring to the maintainers on whether to close this in favour of #3126.

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