feat(rolldown): inline optional-chain enum access#9379
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`try_inline_enum_access` only matched `StaticMemberExpression` /
`ComputedMemberExpression`. Optional-chain enum accesses (`E?.x`,
`E?.['x']`) wrap their inner member in a `ChainExpression`, so the
finalizer never inlined them — the access survived in the output as a
runtime member lookup.
Extend the matcher to also walk through `ChainExpression`, treating
`E?.x` as equivalent to `E.x`: enum bindings are always defined (the
IIFE initializes them to `{}` — never null/undefined), so `?.` cannot
short-circuit. Done before the main `visit_expression` dispatch so we
can pass `expr` to `try_inline_enum_access` without conflicting with
the `ChainExpression` arm's mutable destructure of the inner chain.
With the finalizer now able to inline optional access, drop the
`!prop.optional` guard from the tree-shaker bypass in
`include_statements.rs` (added in #9229 to keep the declaration alive
while the access wasn't inlinable). The `!is_write` guard stays —
writes still aren't inlined.
The `ts_enum_cross_module_inlining_access` fixture moves the optional
cases into the `inlined` group, and the snapshot now folds all 8
inlinable accesses to their literals while preserving the `e_num` /
`e_str` declarations referenced as bare identifiers.
Co-Authored-By: Claude Opus 4.7 <[email protected]>
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## [1.0.1] - 2026-05-13 ### 🚀 Features - experimental/lazy-barrel: advice on oversized barrel modules (#9236) by @shulaoda - rolldown: inline optional-chain enum access (#9379) by @Dunqing - chunk-optimization: dedupe already-loaded dynamic deps (#9305) by @IWANABETHATGUY - binding: call moduleParsed hook in ParallelJsPlugin (#9318) by @jaehafe ### 🐛 Bug Fixes - transform: enable `enum_eval` for `transformSync` and vite TS transform (#9325) by @Dunqing - error: remove severity prefix from diagnostic messages (#9262) by @Kyujenius - deps: pin pnpm to 10.23.0 to work around catalog mismatch on Netlify (#9364) by @shulaoda - ci: pin mimalloc-safe to 0.1.58 (#9361) by @shulaoda - dev/lazy: fix exports of lazy requests in lazy chunks (#9249) by @h-a-n-a - rolldown_plugin_vite_resolve: handle errors in `resolveSubpathImports` callback (#9355) by @sapphi-red - rolldown_plugin_lazy_compilation: use loadExports for fetched proxy to preserve original export names (#9132) by @h-a-n-a - common: include offending index in HybridIndexVec panic message (#9296) by @SAY-5 ### 🚜 Refactor - ecmascript: extract semantic_builder_for_transform helper (#9326) by @Dunqing - test: extract reusable static-import-cycle helper (#9332) by @IWANABETHATGUY ### 📚 Documentation - clarify scope of `topLevelVar` (#9380) by @IWANABETHATGUY - meta/design: add ast-mutation design doc (#9338) by @hyf0 - feat: add ai policy in contribution guide (#9315) by @mdong1909 ### ⚡ Performance - binding: enable mimalloc v3 to reduce idle memory (#9349) by @shulaoda ### 🧪 Testing - mcs: cover require() in `$initial` group (#9376) by @hyf0 - add regression for CJS facade chunk merge into entry (#9351) by @IWANABETHATGUY ### ⚙️ Miscellaneous Tasks - switch prepare-release to manual dispatch with version input (#9383) by @shulaoda - migrate `@rolldown/pluginutils` to `rolldown/plugins` (#9317) by @shulaoda - deps: pin libmimalloc-sys2 to 0.1.54 (#9372) by @shulaoda - replace `igorskyflyer/action-readfile` with `cat` (#9369) by @sapphi-red - deps: update test262 submodule for tests (#9371) by @rolldown-guard[bot] - use app token for test dep update PRs (#9368) by @sapphi-red - replace some actions with gh commands (#9367) by @sapphi-red - replace action-semantic-pull-request with inline regex (#9366) by @sapphi-red - remove pull_request_target workflows (#9188) by @Boshen - deps: upgrade oxc to 0.130.0 (#9360) by @shulaoda - deps: update github actions (major) (#9348) by @renovate[bot] - deps: update github actions (#9341) by @renovate[bot] - deps: update rust crates (#9344) by @renovate[bot] - deps: update crate-ci/typos action to v1.46.1 (#9357) by @renovate[bot] - deps: update npm packages (#9343) by @renovate[bot] - deps: update pnpm to v10.33.4 (#9347) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to ^0.25.0 (#9346) by @renovate[bot] - .claude: add rolldown-repl encoder, rename decode skill (#9352) by @IWANABETHATGUY - deps: update crate-ci/typos action to v1.46.0 (#9345) by @renovate[bot] - deps: update napi to v3.8.6 (#9342) by @renovate[bot] - deps: update dependency vite-plus to v0.1.20 (#9340) by @renovate[bot] - enable rollup chunking-form test (#9335) by @IWANABETHATGUY - typo: fix typo in watcher options comment (#9324) by @thescripted ### ❤️ New Contributors * @Kyujenius made their first contribution in [#9262](#9262) * @SAY-5 made their first contribution in [#9296](#9296) * @thescripted made their first contribution in [#9324](#9324) Co-authored-by: shulaoda <[email protected]>
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We already implemented single file optional chaining inline in Oxc oxc-project/oxc#21834 ## Summary Teaches the cross-module enum inliner to fold optional-chain access (`E?.x`, `E?.['x']`) to the same literal as `E.x` / `E['x']`. With that hole filled, the tree-shaker bypass added in #9229 no longer needs its `!prop.optional` guard. ## Why this is safe Enum bindings are always defined — the generated IIFE initializes them to `{}` (never null/undefined), and const enums are removed entirely after inlining. So `?.` cannot short-circuit on an enum object: `E?.x` is observationally equivalent to `E.x`. The TDZ assumption this relies on (an enum identifier reaching the finalizer is always bound to a real value) is the same one `E.x` inlining already makes — we just extend it to the optional form. ## What changed - `crates/rolldown/src/module_finalizers/mod.rs` — `try_inline_enum_access` now also matches `ChainExpression { StaticMemberExpression | ComputedMemberExpression }`. - `crates/rolldown/src/module_finalizers/impl_visit_mut.rs` — pre-match inline attempt for `ChainExpression`, done before the main `visit_expression` dispatch so `expr` can be passed to `try_inline_enum_access` without conflicting with the existing arm's mutable destructure of the inner chain. - `crates/rolldown/src/stages/link_stage/tree_shaking/include_statements.rs` — drops the `!prop.optional` guard from the enum-decl bypass. `!is_write` stays. - `crates/rolldown/tests/esbuild/ts/ts_enum_cross_module_inlining_access/` — moves the optional cases into the `inlined` group; snapshot now folds all 8 inlinable accesses to literals while keeping `e_num`/`e_str` (bare identifier references). ## Test plan - [x] `cargo test -p rolldown --test integration ts_enum_cross_module_inlining_access` - [x] `cargo test -p rolldown` (1703 passed, 0 failed) - [x] `cargo test -p rolldown --test integration enum` (24 passed) - [x] `cargo test -p rolldown --test integration chain` (25 passed) - [x] Spot-checked single-module `enum E { x = 1 }; console.log(E?.x)` via CLI — now folds to `console.log(1)` - [x] `just ued` — produced no additional snap-diff changes 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.7 <[email protected]>
IWANABETHATGUY
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May 18, 2026
## [1.0.1] - 2026-05-13 ### 🚀 Features - experimental/lazy-barrel: advice on oversized barrel modules (#9236) by @shulaoda - rolldown: inline optional-chain enum access (#9379) by @Dunqing - chunk-optimization: dedupe already-loaded dynamic deps (#9305) by @IWANABETHATGUY - binding: call moduleParsed hook in ParallelJsPlugin (#9318) by @jaehafe ### 🐛 Bug Fixes - transform: enable `enum_eval` for `transformSync` and vite TS transform (#9325) by @Dunqing - error: remove severity prefix from diagnostic messages (#9262) by @Kyujenius - deps: pin pnpm to 10.23.0 to work around catalog mismatch on Netlify (#9364) by @shulaoda - ci: pin mimalloc-safe to 0.1.58 (#9361) by @shulaoda - dev/lazy: fix exports of lazy requests in lazy chunks (#9249) by @h-a-n-a - rolldown_plugin_vite_resolve: handle errors in `resolveSubpathImports` callback (#9355) by @sapphi-red - rolldown_plugin_lazy_compilation: use loadExports for fetched proxy to preserve original export names (#9132) by @h-a-n-a - common: include offending index in HybridIndexVec panic message (#9296) by @SAY-5 ### 🚜 Refactor - ecmascript: extract semantic_builder_for_transform helper (#9326) by @Dunqing - test: extract reusable static-import-cycle helper (#9332) by @IWANABETHATGUY ### 📚 Documentation - clarify scope of `topLevelVar` (#9380) by @IWANABETHATGUY - meta/design: add ast-mutation design doc (#9338) by @hyf0 - feat: add ai policy in contribution guide (#9315) by @mdong1909 ### ⚡ Performance - binding: enable mimalloc v3 to reduce idle memory (#9349) by @shulaoda ### 🧪 Testing - mcs: cover require() in `$initial` group (#9376) by @hyf0 - add regression for CJS facade chunk merge into entry (#9351) by @IWANABETHATGUY ### ⚙️ Miscellaneous Tasks - switch prepare-release to manual dispatch with version input (#9383) by @shulaoda - migrate `@rolldown/pluginutils` to `rolldown/plugins` (#9317) by @shulaoda - deps: pin libmimalloc-sys2 to 0.1.54 (#9372) by @shulaoda - replace `igorskyflyer/action-readfile` with `cat` (#9369) by @sapphi-red - deps: update test262 submodule for tests (#9371) by @rolldown-guard[bot] - use app token for test dep update PRs (#9368) by @sapphi-red - replace some actions with gh commands (#9367) by @sapphi-red - replace action-semantic-pull-request with inline regex (#9366) by @sapphi-red - remove pull_request_target workflows (#9188) by @Boshen - deps: upgrade oxc to 0.130.0 (#9360) by @shulaoda - deps: update github actions (major) (#9348) by @renovate[bot] - deps: update github actions (#9341) by @renovate[bot] - deps: update rust crates (#9344) by @renovate[bot] - deps: update crate-ci/typos action to v1.46.1 (#9357) by @renovate[bot] - deps: update npm packages (#9343) by @renovate[bot] - deps: update pnpm to v10.33.4 (#9347) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to ^0.25.0 (#9346) by @renovate[bot] - .claude: add rolldown-repl encoder, rename decode skill (#9352) by @IWANABETHATGUY - deps: update crate-ci/typos action to v1.46.0 (#9345) by @renovate[bot] - deps: update napi to v3.8.6 (#9342) by @renovate[bot] - deps: update dependency vite-plus to v0.1.20 (#9340) by @renovate[bot] - enable rollup chunking-form test (#9335) by @IWANABETHATGUY - typo: fix typo in watcher options comment (#9324) by @thescripted ### ❤️ New Contributors * @Kyujenius made their first contribution in [#9262](#9262) * @SAY-5 made their first contribution in [#9296](#9296) * @thescripted made their first contribution in [#9324](#9324) Co-authored-by: shulaoda <[email protected]>
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We already implemented single file optional chaining inline in Oxc oxc-project/oxc#21834
Summary
Teaches the cross-module enum inliner to fold optional-chain access (
E?.x,E?.['x']) to the same literal asE.x/E['x']. With that hole filled, the tree-shaker bypass added in #9229 no longer needs its!prop.optionalguard.Why this is safe
Enum bindings are always defined — the generated IIFE initializes them to
{}(never null/undefined), and const enums are removed entirely after inlining. So?.cannot short-circuit on an enum object:E?.xis observationally equivalent toE.x.The TDZ assumption this relies on (an enum identifier reaching the finalizer is always bound to a real value) is the same one
E.xinlining already makes — we just extend it to the optional form.What changed
crates/rolldown/src/module_finalizers/mod.rs—try_inline_enum_accessnow also matchesChainExpression { StaticMemberExpression | ComputedMemberExpression }.crates/rolldown/src/module_finalizers/impl_visit_mut.rs— pre-match inline attempt forChainExpression, done before the mainvisit_expressiondispatch soexprcan be passed totry_inline_enum_accesswithout conflicting with the existing arm's mutable destructure of the inner chain.crates/rolldown/src/stages/link_stage/tree_shaking/include_statements.rs— drops the!prop.optionalguard from the enum-decl bypass.!is_writestays.crates/rolldown/tests/esbuild/ts/ts_enum_cross_module_inlining_access/— moves the optional cases into theinlinedgroup; snapshot now folds all 8 inlinable accesses to literals while keepinge_num/e_str(bare identifier references).Test plan
cargo test -p rolldown --test integration ts_enum_cross_module_inlining_accesscargo test -p rolldown(1703 passed, 0 failed)cargo test -p rolldown --test integration enum(24 passed)cargo test -p rolldown --test integration chain(25 passed)enum E { x = 1 }; console.log(E?.x)via CLI — now folds toconsole.log(1)just ued— produced no additional snap-diff changes🤖 Generated with Claude Code