fix: reconstruct nested rest patterns in into_expression#9980
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Merging this PR will improve performance by 3.4%
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| Benchmark | BASE |
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Efficiency | |
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| ⚡ | bundle@multi-duplicated-top-level-symbol |
262.4 ms | 253.8 ms | +3.4% |
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Comparing 06-26-fix_handle_nested_rest_in_into_expression (30806eb) with main (0b8e929)
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Stacked on #9976. ### What this solves After #9976, `BindingPattern::into_expression` rebuilds rest elements as spreads, but it still assumes the rest *argument* is a `BindingIdentifier` and panics via `unreachable!` otherwise: ```rust let BindingPattern::BindingIdentifier(ref id) = rest.argument else { unreachable!("The rest element should be `BindingIdentifier`") }; ``` That assumption holds for **object** rest — the grammar forces `{ a, ...rest }` to bind an identifier — but not for **array** rest. Both of these are legal JS where the rest argument is a nested pattern: ```js const [a, ...[b, c]] = x; // rest argument is an ArrayPattern const [a, ...{ length }] = x; // rest argument is an ObjectPattern ``` So `into_expression` could panic on a perfectly valid pattern. (As noted in #9976, the array path isn't reached today by the only caller — the Vite `__vitePreload` rewrite — because a namespace object isn't iterable, so this is a latent panic rather than an active miscompile.) ### The fix Recurse through `into_expression` on the rest argument instead of asserting it is an identifier, mirroring the sibling `into_assignment_target`, which already does exactly this for both object and array rest with no guard. The rebuilt spread now round-trips any nested rest pattern. The object path is unchanged behaviorally (its argument is always an identifier) but now shares the same uniform code path. Adds a regression test (`const [a, ...[b, c]] = x;`) that would hit the old `unreachable!`.
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## [1.1.4] - 2026-07-01 ### 🚀 Features - disable `experimental.lazyBarrel` by default (#10071) by @shulaoda ### 🐛 Bug Fixes - dev: disable lazy barrel in dev mode (#10060) by @shulaoda - generate: keep full JSON interface under preserveModules namespa… (#10056) by @IWANABETHATGUY - check finalize_other_specifiers in its own Debug attribute (#10032) by @shulaoda - serialize the KeepAssign unused minify option as "keep_assign" (#10031) by @shulaoda - keep fragments after the newline fragment in MagicString::last_line (#10023) by @shulaoda - generate: undeclared JSON named exports under preserveModules (#10020) (#10027) by @IWANABETHATGUY - deconflict: rename CJS-wrapped locals that shadow chunk-root bindings (#9921) by @IWANABETHATGUY - rolldown: keep entry facade when a shared chunk holds another entry's module (#9997) by @hyf0 - treeshake: also bail JSON default split when the object escapes (#9996) by @IWANABETHATGUY - don't classify await in a strict-mode function as top-level await (#9987) by @shulaoda - avoid spurious leading newline in addon hooks (banner/footer/intro/outro) (#9989) by @shulaoda - handle JSON default mutation bailouts (#9972) by @TheAlexLichter - plugin: make lazy hook metadata enumerable (#9991) by @TheAlexLichter - dev: make init errors in lazy-compiled modules catchable (#9981) by @h-a-n-a - treeshake: keep computed-key side effects on namespace member access (#9986) by @shulaoda - binding: validate replace plugin delimiters length instead of panicking (#9984) by @shulaoda - reconstruct nested rest patterns in into_expression (#9980) by @IWANABETHATGUY - reconstruct rest patterns as spread in into_expression (#9976) by @shulaoda - preserve export keyword on multi-declarator exports under keepNames (#9974) by @shulaoda - deterministically keep the shortest name for deduplicated assets (#9948) by @x1024 - treeshake: apply @__NO_SIDE_EFFECTS__ to cross-chunk namespace calls (#9960) by @IWANABETHATGUY ### 🚜 Refactor - drop redundant program scope enter/leave in finalizer (#10049) by @shulaoda - deconflict: extract collect_chunk_scope_captured_names (#10006) by @IWANABETHATGUY - unify pre-scan multi-declarator split into one decision site (#9982) by @IWANABETHATGUY - common: return bool from SymbolRef::is_not_reassigned (#9962) by @IWANABETHATGUY ### 📚 Documentation - rolldown: remove outdated comment for removing parenthesized expression (#10062) by @Dunqing - use GitHub-flavored alert for Etiquette note in contribution guide (#10012) by @IWANABETHATGUY - replace: explain the delimiters left and right boundaries (#9985) by @shulaoda - ast-mutation: remove stale Address Use section after pre-scan refactor (#9983) by @IWANABETHATGUY - remove fathom (#9968) by @mdong1909 - contribution-guide: code-format main branch references (#9966) by @IWANABETHATGUY - contribution-guide: fix stale REPL note and tidy wording (#9957) by @hyf0 - contribution-guide: clarify when to discuss before opening a PR (#9955) by @hyf0 ### ⚡ Performance - disable preserve_parens across all parse paths (#10057) by @Dunqing - common: inline declared_symbols with SmallVec (#9920) by @IWANABETHATGUY - common: pack TaggedSymbolRef into 8 bytes (#9919) by @IWANABETHATGUY - sourcemap: skip newline scan on the no-sourcemap join fast path (#9936) by @Boshen ### 🧪 Testing - dev: error in lazy module should be catchable (#9975) by @sapphi-red - dev: reject unknown lazy compile modules (#9969) by @sapphi-red ### ⚙️ Miscellaneous Tasks - deps: update actions/cache action to v6 (#10001) by @renovate[bot] - trigger vite ecosystem-ci from PR comments (#10058) by @shulaoda - deps: update napi to v3.10.0 (#10063) by @renovate[bot] - remove unused From impl for RolldownLabelSpan (#10055) by @shulaoda - remove dead Diagnostic::with_kind method (#10054) by @shulaoda - remove unused StatementExt methods (#10053) by @shulaoda - remove unused ExpressionExt methods (#10052) by @shulaoda - remove commented-out re_export_all_names field (#10051) by @shulaoda - deps: update pnpm to v11.9.0 (#10047) by @renovate[bot] - remove the unused BindingGenerateHmrPatchReturn napi type (#10034) by @shulaoda - remove the dead inline_entry_chunk_wrapping scaffolding (#10037) by @shulaoda - deps: bump oxc_resolver to 11.22.0 (#10045) by @Boshen - remove never-constructed MatchImportKind::_Ignore variant (#10041) by @shulaoda - remove the unused ScheduledBuild napi struct (#10033) by @shulaoda - remove dead compute_hmr_update_single method (#10040) by @shulaoda - drop the redundant visited.insert in manual code splitting (#10038) by @shulaoda - remove the dead output_assets vector in render_chunk_to_assets (#10036) by @shulaoda - remove the unused From<String>/Display impls for BindingLogLevel (#10035) by @shulaoda - deps: upgrade oxc to 0.138.0 and migrate to per-type AST construction (#10018) by @shulaoda - deps: update rust crates (#9911) by @renovate[bot] - deps: update test262 submodule for tests (#10016) by @rolldown-guard[bot] - deps: update github actions (#9999) by @renovate[bot] - deps: update npm packages (#10000) by @renovate[bot] ###◀️ Revert - "fix(plugin): make lazy hook metadata enumerable (#9991)" (#10005) by @shulaoda ### ❤️ New Contributors * @x1024 made their first contribution in [#9948](#9948) Co-authored-by: shulaoda <165626830+shulaoda@users.noreply.github.com>
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Stacked on #9976.
What this solves
After #9976,
BindingPattern::into_expressionrebuilds rest elements as spreads, but it still assumes the rest argument is aBindingIdentifierand panics viaunreachable!otherwise:That assumption holds for object rest — the grammar forces
{ a, ...rest }to bind an identifier — but not for array rest. Both of these are legal JS where the rest argument is a nested pattern:So
into_expressioncould panic on a perfectly valid pattern. (As noted in #9976, the array path isn't reached today by the only caller — the Vite__vitePreloadrewrite — because a namespace object isn't iterable, so this is a latent panic rather than an active miscompile.)The fix
Recurse through
into_expressionon the rest argument instead of asserting it is an identifier, mirroring the siblinginto_assignment_target, which already does exactly this for both object and array rest with no guard. The rebuilt spread now round-trips any nested rest pattern. The object path is unchanged behaviorally (its argument is always an identifier) but now shares the same uniform code path.Adds a regression test (
const [a, ...[b, c]] = x;) that would hit the oldunreachable!.