fix: preserve optional chaining in namespace member expr rewrite by Copilot · Pull Request #8712 · rolldown/rolldown

Copilot · 2026-03-15T14:25:54Z

Summary

Fixes namespace member expression rewriting to preserve optional chaining on unresolved runtime properties while still allowing full tree-shaking through nested namespace chains.
Introduces MemberExprProp struct to propagate each property's optional flag through the scanner, linker, and finalizer pipeline.
Wraps rewritten expressions in ChainExpression when the result contains optional member accesses.

Test plan

optional_chain_namespace test: h.app?.user?.name preserves ?. after h.app is inlined
optional_chainning_namespace test: foo?.bar?.value through nested namespaces tree-shakes to console.log("used")
optional_chainning_namespace_2 test: mixed namespace + runtime optional chain
Full integration suite (1642 tests pass, 0 failures)
Clippy clean

netlify · 2026-03-15T14:26:08Z

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crates/rolldown/tests/rolldown/issues/optional_chain_namespace/artifacts.snap

Copilot

Pull request overview

Fixes a correctness bug where optional chaining (?.) could be stripped during namespace member-expression rewriting (e.g. ns.app?.user?.name), causing runtime TypeErrors. This change adjusts AST scanning so resolution stops before optional boundaries, preserving ?. semantics while still allowing safe namespace import resolution.

Changes:

Update try_extract_parent_static_member_expr_chain to stop collecting a member-expression chain once an optional member expression is encountered past the first property.
Add a regression test case under crates/rolldown/tests/rolldown/issues/optional_chain_namespace/ that asserts the bundle executes and preserves optional chaining after rewriting.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
crates/rolldown/src/ast_scanner/mod.rs	Stops member-chain extraction at optional member expressions (after the first prop) to avoid rewriting across `?.` boundaries.
crates/rolldown/tests/rolldown/issues/optional_chain_namespace/state.js	Test fixture exporting `app` with a null inner value to exercise optional chaining behavior.
crates/rolldown/tests/rolldown/issues/optional_chain_namespace/main.js	Regression test asserting optional chaining on a namespace import remains safe after bundling.
crates/rolldown/tests/rolldown/issues/optional_chain_namespace/artifacts.snap	Snapshot verifying generated output preserves `?.` operators.
crates/rolldown/tests/rolldown/issues/optional_chain_namespace/_config.json	Test configuration enabling execution verification on Node.

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crates/rolldown/src/ast_scanner/mod.rs

crates/rolldown/tests/rolldown/issues/optional_chain_namespace/main.js

crates/rolldown/tests/rolldown/issues/optional_chain_namespace/artifacts.snap

github-actions · 2026-03-15T15:09:14Z

Benchmarks Rust

target: main(dff6613)
pr: copilot/fix-optional-chaining-bug(54c113e)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.00     65.0±2.21ms        ? ?/sec    1.00     64.8±2.87ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.01     72.9±1.88ms        ? ?/sec    1.00     71.9±1.52ms        ? ?/sec
bundle/bundle@rome_ts                                        1.01    139.3±7.72ms        ? ?/sec    1.00    137.9±2.75ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.01    158.9±7.78ms        ? ?/sec    1.00    157.8±2.91ms        ? ?/sec
bundle/bundle@threejs                                        1.02     61.4±3.84ms        ? ?/sec    1.00     60.2±2.01ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.03     71.8±3.96ms        ? ?/sec    1.00     69.9±1.13ms        ? ?/sec
bundle/bundle@threejs10x                                     1.01    703.4±5.81ms        ? ?/sec    1.00    699.3±9.32ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.00    804.9±4.85ms        ? ?/sec    1.01    813.1±8.91ms        ? ?/sec

IWANABETHATGUY · 2026-03-15T15:54:32Z

fix: preserve optional chaining in namespace member expr rewrite #8712 👈 (View in Graphite)
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codspeed-hq · 2026-03-15T16:25:24Z

Merging this PR will not alter performance

✅ 6 untouched benchmarks
⏩ 8 skipped benchmarks¹

_{Comparing copilot/fix-optional-chaining-bug (54c113e) with main (88acaad)²}

8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩
No successful run was found on main (dff6613) during the generation of this report, so 88acaad was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

IWANABETHATGUY · 2026-03-15T16:36:00Z

The original implementation of Copilot is incorrect, so I rewrote it with CC

Copilot

Pull request overview

Fixes a correctness bug in rolldown’s namespace member-expression rewriting so optional chaining (?.) is preserved through the scan → link → finalize pipeline, preventing runtime TypeErrors while still allowing deep namespace-chain tree-shaking (closes #8710).

Changes:

Introduce MemberExprProp to carry { name, span, optional } for each property in a member-expression chain.
Update AST snippet generation and member-expr resolution to propagate optional flags into rewritten member expressions.
Ensure rewritten optional member expressions remain valid JS by keeping/wrapping them in ChainExpression when needed, and add regression tests/snapshots.

Reviewed changes

Copilot reviewed 22 out of 22 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
crates/rolldown_ecmascript_utils/src/ast_snippet.rs	Build member-expression chains using `MemberExprProp.optional` instead of always non-optional accesses.
crates/rolldown_common/src/types/member_expr_ref_resolution.rs	Store resolved chain props as `Vec<MemberExprProp>` (instead of `(name, span)` tuples).
crates/rolldown_common/src/types/member_expr_ref.rs	Add `MemberExprProp` and migrate `MemberExprRef` to use it.
crates/rolldown_common/src/lib.rs	Re-export `MemberExprProp` for downstream crates.
crates/rolldown/src/stages/link_stage/bind_imports_and_exports.rs	Update member-expr resolution logic to use `prop.name` from `MemberExprProp`.
crates/rolldown/src/module_finalizers/impl_visit_mut.rs	Preserve optional chaining validity by re-wrapping rewritten optional member accesses in `ChainExpression`.
crates/rolldown/src/ast_scanner/mod.rs	Collect member-expression chains as `Vec<MemberExprProp>` including `optional` flags.
crates/rolldown/src/ast_scanner/impl_visit.rs	Adjust downstream accesses to tuple→struct (`prop[0].name`, etc.).
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace_2/main.js	New tree-shaking regression test covering mixed namespace + runtime optional chain.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace_2/foo.js	Fixture for optional chaining tree-shaking test.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace_2/bar.js	Fixture exports for tree-shaking verification.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace_2/artifacts.snap	Snapshot asserting optional chaining is preserved post-rewrite.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace_2/_config.json	Integration test config for the new fixture.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace/main.js	New tree-shaking regression test covering nested namespaces with optional chaining.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace/foo.js	Fixture re-exporting namespace for tree-shaking case.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace/bar.js	Fixture exports for tree-shaking verification.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace/artifacts.snap	Snapshot asserting full tree-shaking to the used value.
crates/rolldown/tests/rolldown/tree_shaking/optional_chainning_namespace/_config.json	Integration test config for the new fixture.
crates/rolldown/tests/rolldown/issues/optional_chain_namespace/state.js	New issue repro fixture module exporting an object with `null` leaf.
crates/rolldown/tests/rolldown/issues/optional_chain_namespace/main.js	Regression asserting optional chaining is preserved for both static and computed property access.
crates/rolldown/tests/rolldown/issues/optional_chain_namespace/artifacts.snap	Snapshot verifying rewritten output keeps `?.` semantics.
crates/rolldown/tests/rolldown/issues/optional_chain_namespace/_config.json	Integration config (node platform + executed expectation) for issue repro.

crates/rolldown/src/module_finalizers/impl_visit_mut.rs

crates/rolldown_common/src/types/member_expr_ref_resolution.rs

IWANABETHATGUY · 2026-03-16T01:58:13Z

Merge activity

Mar 16, 1:58 AM UTC: The merge label 'graphite: merge-when-ready' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Mar 16, 2:02 AM UTC: IWANABETHATGUY added this pull request to the Graphite merge queue.
Mar 16, 2:06 AM UTC: Merged by the Graphite merge queue.

## Summary - Fixes namespace member expression rewriting to preserve optional chaining on unresolved runtime properties while still allowing full tree-shaking through nested namespace chains. - Introduces MemberExprProp struct to propagate each property's optional flag through the scanner, linker, and finalizer pipeline. - Wraps rewritten expressions in ChainExpression when the result contains optional member accesses. Closes #8710 ## Test plan - [x] optional_chain_namespace test: h.app?.user?.name preserves ?. after h.app is inlined - [x] optional_chainning_namespace test: foo?.bar?.value through nested namespaces tree-shakes to console.log("used") - [x] optional_chainning_namespace_2 test: mixed namespace + runtime optional chain - [x] Full integration suite (1642 tests pass, 0 failures) - [x] Clippy clean

@IWANABETHATGUY

## [1.0.0-rc.10] - 2026-03-18 ### 🚀 Features - add indentExclusionRanges property to MagicString (#8746) by @IWANABETHATGUY - expose `oxcRuntimePlugin` (#8654) by @sapphi-red - rust: make bundler generic over FileSystem for in-memory benchmarks (#8652) by @Boshen ### 🐛 Bug Fixes - rolldown_plugin_vite_dynamic_import_vars: align dynamic import fast check with Vite (#8760) by @shulaoda - renamer: handle existing bindings in nested scopes when finding unique names (#8741) by @drewolson - pass `yarn_pnp` option where needed (#8736) by @sapphi-red - preserve optional chaining in namespace member expr rewrite (#8712) by @Copilot - correct UTF-16 index handling in native MagicString (#8693) by @IWANABETHATGUY - mark failing doctests as ignore (#8700) by @Boshen - prevent may_partial_namespace from leaking through include_module (#8682) by @IWANABETHATGUY - ci: bump native-build cache key to invalidate stale napi-rs artifacts (#8678) by @Boshen - `comments.annotation: false` breaking tree-shaking (#8657) by @IWANABETHATGUY - validate filenames for NUL bytes from chunkFileNames/entryFileNames (#8644) by @IWANABETHATGUY - dce-only minify should not set NODE_ENV to production (#8651) by @IWANABETHATGUY ### 🚜 Refactor - rust: remove dead `CrossModuleOptimizationConfig::side_effects_free_function_optimization` (#8673) by @Dunqing - rust: simplify `cross_module_optimization` by removing redundant scope tracking (#8672) by @Dunqing - simplify string repeat in guess_indentor (#8753) by @IWANABETHATGUY - consolidate custom magic-string tests into one file (#8696) by @IWANABETHATGUY - extract CJS bailout checks from include_symbol (#8683) by @IWANABETHATGUY - rust: remove `BindingIdentifierExt` to use `BindingIdentifier::symbol_id()` instead (#8667) by @Dunqing - bench: add bench_preset helper and inline presets (#8658) by @Boshen - rust: filter external modules from entries instead of mapping bit positions (#8637) by @Dunqing ### 📚 Documentation - clarify watch mode behavior and its limitations (#8751) by @sapphi-red - add external link icon to GitHub button in Hero section (#8731) by @thisisnkc - guide: clarify that `inject` option is only conceptually similar to esbuild's one (#8743) by @sapphi-red - meta/design: add `devtools.md` (#8663) by @hyf0 - add viteplus alpha announcement banner (#8668) by @shulaoda ### ⚡ Performance - rolldown: some minor perf optimization found by autoresearch (#8730) by @Brooooooklyn - replace Vec allocation with lazy iterator in find_hash_placeholders (#8703) by @Boshen - replace TypedDashMap with TypedMap in CustomField (#8708) by @Boshen - bench: remove scan benchmark binary to halve LTO link time (#8694) by @Boshen ### 🧪 Testing - watch: increase timeout for error output (#8766) by @sapphi-red - vite-tests: remove JS plugin tests (#8767) by @sapphi-red - watch: add CLI exit code test (#8752) by @sapphi-red - normalize paths on Windows even if `resolve.symlinks` is false (#8483) by @sapphi-red ### ⚙️ Miscellaneous Tasks - correct comment in bundle-analyzer-plugin.ts (#8770) by @origami-z - upgrade oxc to 0.120.0 (#8764) by @Boshen - enable all test for `reset` category in MagicString.test.ts (#8749) by @IWANABETHATGUY - deps: update test262 submodule for tests (#8742) by @sapphi-red - deps: update oxc apps (#8734) by @renovate[bot] - deps: update softprops/action-gh-release action to v2.6.1 (#8724) by @renovate[bot] - deps: update npm packages (major) (#8722) by @renovate[bot] - deps: update github-actions (major) (#8721) by @renovate[bot] - deps: update softprops/action-gh-release action to v2.6.0 (#8720) by @renovate[bot] - deps: update npm packages (#8718) by @renovate[bot] - deps: update rust crates (#8717) by @renovate[bot] - deps: update github-actions (#8716) by @renovate[bot] - deps: update dependency oxlint-tsgolint to v0.17.0 (#8713) by @renovate[bot] - deps: bump cargo-shear to v1.11.2 (#8711) by @Boshen - use org level `CODE_OF_CONDUCT.md` (#8706) by @sapphi-red - fix cache key mismatch and remove redundant cache saves (#8695) by @Boshen - deps: update oxc apps (#8692) by @renovate[bot] - deps: update oxc apps (#8649) by @renovate[bot] - should do matrix out side of reusable workflows 2 (#8691) by @hyf0 - should do matrix out side of reusable workflows (#8690) by @hyf0 - deps: update dependency rolldown-plugin-dts to v0.22.5 (#8689) by @renovate[bot] - upgrade oxc to 0.119.0 and oxc_resolver to 11.19.1 (#8686) by @Boshen - correct if condition of `type-check` job (#8677) by @hyf0 - Gate CI type-check job on node changes (#8669) by @Copilot - benchmark: improve codspeed build (#8665) by @Boshen - deps: update oxc to v0.118.0 (#8650) by @renovate[bot] - deps: update crate-ci/typos action to v1.44.0 (#8647) by @renovate[bot] - deps: update oxc resolver to v11.19.1 (#8646) by @renovate[bot] - deps: update dependency rust to v1.94.0 (#8648) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.22.4 (#8645) by @renovate[bot] ### ◀️ Revert - Revert "ci: Gate CI type-check job on node changes" (#8674) by @hyf0 - "chore(deps): update dependency rust to v1.94.0 (#8648)" (#8660) by @shulaoda ### ❤️ New Contributors * @origami-z made their first contribution in [#8770](#8770) * @drewolson made their first contribution in [#8741](#8741) * @thisisnkc made their first contribution in [#8731](#8731) Co-authored-by: shulaoda <165626830+shulaoda@users.noreply.github.com>

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Copilot AI changed the title ~~[WIP] Fix optional chaining stripping bug in namespace member expressions~~ fix: preserve optional chaining when rewriting namespace member expressions Mar 15, 2026

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IWANABETHATGUY force-pushed the copilot/fix-optional-chaining-bug branch from 7fcd1ce to 9ad21f7 Compare March 15, 2026 15:54

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IWANABETHATGUY changed the title ~~fix: preserve optional chaining when rewriting namespace member expressions~~ fix: preserve optional chaining in namespace member expr rewrite Mar 15, 2026

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Miodec mentioned this pull request Mar 15, 2026

fix: cannot read properties of null (@alexmgullen) monkeytypegame/monkeytype#7653

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fix: preserve optional chaining in namespace member expr rewrite#8712

fix: preserve optional chaining in namespace member expr rewrite#8712
graphite-app[bot] merged 1 commit intomainfrom
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