refactor: separate tree-shaking side effects from execution order sensitivity#10168
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Pull request overview
This PR refactors Rolldown’s statement evaluation analysis to explicitly separate tree-shaking side-effect facts (public StmtEvalFlags) from execution-order sensitivity (analyzer-local reasons), so execution-order metadata doesn’t accidentally influence removal decisions.
Changes:
- Introduces
StmtEvalFacts(tree-shaking flags + order-sensitive reasons) and updates the statement analyzer to return facts rather than a shared bitset. - Updates AST scanning to set
EcmaViewMeta::ExecutionOrderSensitivebased onStmtEvalFacts::is_order_sensitive(), while storing only tree-shaking flags inStmtInfo. - Adjusts cross-module optimization to refresh only
tree_shaking_flags()since it mutates removal-related metadata, not execution-order metadata.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| crates/rolldown/src/stages/link_stage/cross_module_optimization.rs | Uses the analyzer’s new return type but persists only tree-shaking flags during mutation refresh. |
| crates/rolldown/src/ast_scanner/stmt_eval_analyzer/mod.rs | Adds StmtEvalFacts + order-sensitive reasons and rewires analysis/folding logic to keep channels separate. |
| crates/rolldown/src/ast_scanner/impl_visit.rs | Updates module scanning to store only tree-shaking flags in StmtInfo and to mark execution-order sensitivity via is_order_sensitive(). |
| crates/rolldown_common/src/types/stmt_eval_flags.rs | Narrows StmtEvalFlags to tree-shaking-relevant flags only. |
Merging this PR will not alter performance
Comparing Footnotes
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…sitivity (#10168) ### What This PR splits the statement eval analyzer result into two separate answers: - tree-shaking side effects, stored in the public `StmtEvalFlags` - execution-order sensitivity, represented by analyzer-local order-sensitive reasons `StmtInfo::side_effects()` continues to carry only the tree-shaking flags. `EcmaViewMeta::ExecutionOrderSensitive` now comes from `StmtEvalFacts::is_order_sensitive()`, which combines unknown runtime side effects with order-sensitive reasons such as global reads and pure annotations. The cross-module optimization pass still re-runs the analyzer, but it consumes only `tree_shaking_flags()` because that pass mutates removal-related metadata, not module execution-order metadata. ### Why Rolldown needs to answer two different questions: - Can this statement or module be removed without observable behavior? - Does this statement or module need to keep its relative execution timing? Keeping both answers in the same public bitset makes later order-sensitive facts look like tree-shaking side effects. That can affect chunk dependency edges or removal decisions for the wrong reason. This PR is intended as a refactor that keeps existing behavior while making those two answers explicit. ### Tests - `cargo test -p rolldown stmt_eval_analyzer --lib` - `cargo check -p rolldown`
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…ive (#10180) Stacked on #10168. ### What Adds `TopLevelImportReadDetector` — a dedicated, uniform AST walk that marks a top-level statement as execution-order sensitive when its module-evaluation-time execution reads an imported binding — and OR-es it into `EcmaViewMeta::ExecutionOrderSensitive`. ### Why On-demand wrapping should eventually decide "wrap or not" from execution-order sensitivity alone, so that a module which imports dependencies but only uses them inside function/class bodies can stay unwrapped. For that, the order-sensitivity signal must be **complete**: it may never miss a top-level read of an imported binding, or such a module could be unwrapped and reordered across a mutation. The earlier approach (#10169) threaded this fact through the per-expression-form side-effect analyzer, which is exactly how gaps slip in — e.g. an imported binding in a mid-chain computed key (`a[imp].y`) or a namespace aliased into a local (`const x = ns; x.foo`). This replaces that with a single uniform walk that visits every sub-node once, so no expression form can be missed and newly added syntax is covered by default. It is a deliberate over-approximation, which is the sound direction for wrapping (under-reporting is the only dangerous mistake). Skipped, and why each stays sound: - **Function / arrow bodies** (incl. class method bodies and parameter defaults) run at call time. If such a body runs during module evaluation it does so through a call / `new`, which the side-effect / pure-annotation analysis already reports as order-sensitive. - **Import declarations and re-export specifiers** (`export { a }`, `export { a } from '...'`) forward bindings without reading a value, so pure barrels stay unmarked. - **Type annotations** are erased at runtime. Known limitation, inherent to any syntactic analysis: under `treeshake.propertyReadSideEffects: false`, a getter / `Proxy` trap that reads an imported binding is invisible here — that is the option's own "reads are side-effect-free" promise, not a gap this walk can close. ### Currently inert Every unwrap / chunk-grouping consumer of `ExecutionOrderSensitive` is additionally gated by `import_records.is_empty()`, and a module that reads an import necessarily has an import record, so no wrap or chunk decision changes yet. This lands the detection ahead of the follow-up that drops the `import_records.is_empty()` gate and lets the flag decide unwrapping on its own. ### Tests - `cargo test -p rolldown --lib top_level_import_read` — 6 new unit tests: direct / member / computed-key / compound reads; the `a[key].y` mid-chain computed-key and `const x = ns; x.foo` namespace-alias cases; function / arrow / method bodies skipped; re-export barrels and locals not flagged; static field initializer and `extends` clause. - `cargo fmt --check` and `cargo clippy -p rolldown --lib --tests` clean. - Full integration suite unchanged — the change is inert; the strict-execution-order / wrapping / on-demand fixtures are green.
## [1.1.5] - 2026-07-08 ### 🚀 Features - detect top-level import-binding reads as execution-order sensitive (#10180) by @hyf0 - sourcemap_filenames: add a sourcemapFileNames option (#9271) by @V1OL3TF0X - binding: record plugin hook result kind in tracing spans (#10154) by @IWANABETHATGUY - linking: skip side-effect-free modules in per-entry reachability (#10111) by @IWANABETHATGUY - improve error message for unresolved virtual imports (#10156) by @sapphi-red - add descriptive metadata to plugin API (#10106) by @sapphi-red - add `--configLoader=native` option (#10118) by @sapphi-red ### 🐛 Bug Fixes - improve invalid annotation warnings (#10185) by @hyf0 - keep deduplicated asset filenames stable once they can be observed (#10191) by @shulaoda - sourcemap_filenames: use public option name in pattern errors (#10188) by @IWANABETHATGUY - sourcemap_filenames: hash prepared sourcemap content (#10178) by @hyf0 - tree-shake unused circular declarators exported via export list (#10166) by @IWANABETHATGUY - dev: don't panic when an HMR rebuild hits an unresolved import (#10162) by @shulaoda - propagate errors from output.globals function (#9880) by @shulaoda - dev: revert cache mutations when a partial scan fails (#10110) by @shulaoda - dev: update importer relationships of cached modules in incremental build (#10107) by @shulaoda - hmr: fall back to full reload when a changed module is not registered as executed (#10132) by @shulaoda - chunk-optimizer: follow entry facade edges in runtime placement cycle check (#10101) by @hyf0 - dev: ignore watcher events after close (#10113) by @hyf0 - emit async wrapper for TLA modules under onDemandWrapping (#10086) by @IWANABETHATGUY - gate sideEffects:false modules' side effects on body demand (#10080) by @IWANABETHATGUY - rolldown_plugin_vite_resolve: return empty object for `browser: false` mapped modules (#10082) by @sapphi-red - reset the word-boundary state on newline in Hires::Boundary sourcemaps (#10025) by @shulaoda - trim an emptied chunk's outro/intro instead of skipping past it (#10029) by @shulaoda - test each edited chunk's own start against indent exclude ranges (#10026) by @shulaoda - preserve sourcemap mappings for indented lines when a CJS module shares the chunk (#10074) by @hyf0 ### 🚜 Refactor - separate tree-shaking side effects from execution order sensitivity (#10168) by @hyf0 - type construct_vite_preload_call to take an ObjectPattern (#10135) by @shulaoda - treeshake: single-source the own-export classification shared with the lazy-barrel loader (#10098) by @IWANABETHATGUY - dev: reuse Vite's bundledDev server (#10081) by @h-a-n-a - clippy: ban std HashMap/HashSet in favour of FxHashMap/FxHashSet (#10108) by @Boshen - treeshake: make body demand a second module bit instead of a stmt multimap (#10097) by @IWANABETHATGUY - seal used_symbol_refs by construction after its last writer (#10091) by @hyf0 - treeshake: replace inclusion mutual recursion with a worklist engine (#10096) by @IWANABETHATGUY - treeshake: split include_statements.rs into focused modules (#10095) by @IWANABETHATGUY - drop redundant is_user_defined filter on partitioned entries (#10050) by @shulaoda - project the retained export interface out of used_symbol_refs (#10089) by @hyf0 - track used external symbols separately from used_symbol_refs (#10088) by @hyf0 - make module namespace inclusion an explicit linking metadata field (#10087) by @hyf0 - rename statement evaluation metadata (#10078) by @hyf0 ### 📚 Documentation - virtual modules user-facing id convention (#10155) by @sapphi-red - cli: clarify disabling boolean/object flags like codeSplitting (#10153) by @IWANABETHATGUY - chore: remove Vite+ alpha banner (#10105) by @mdong1909 - write down the used_symbol_refs contract (#10090) by @hyf0 - dev/lazy: update design and implementation (#10079) by @h-a-n-a ### ⚡ Performance - ast_scanner: stop order-sensitivity checks once a module is flagged (#10190) by @IWANABETHATGUY - return impl ExactSizeIterator from slice-backed accessors (#10133) by @Boshen - binding: box dev and watcher napi futures (#10103) by @Boshen ### 🧪 Testing - move string_wizard replace unit tests to the JS magic-string suite (#10176) by @IWANABETHATGUY - dev: assert incremental scan state matches a fresh full build after each HMR step (#10115) by @shulaoda - dev: restore runtime assertions of delete_file_not_used_anymore (#10112) by @shulaoda - dev: fix flaky dev server tests in CI (#10152) by @h-a-n-a - add regression test for #10099 (lazyBarrel drops default-import binding but keeps its property reads) (#10109) by @IWANABETHATGUY ### ⚙️ Miscellaneous Tasks - deploy website to Void via GitHub OIDC (#10192) by @Boshen - deps: update oxc to 0.139.0 (#10161) by @shulaoda - deps: update test262 submodule for tests (#10160) by @rolldown-guard[bot] - rolldown_plugin_utils: remove dead asset-url and css scaffolding (#10131) by @shulaoda - deps: revert vite-plus to v0.2.1 (#10148) by @shulaoda - deps: update github actions (#10141) by @renovate[bot] - deps: update dependency rust to v1.96.1 (#10145) by @renovate[bot] - deps: update npm packages (#10142) by @renovate[bot] - deps: update rust crates (#10143) by @renovate[bot] - deps: update napi to v3.10.3 (#10121) by @renovate[bot] - rolldown_utils: remove unused time module (#10138) by @shulaoda - remove dead CopyModulePlugin::is_active method (#10129) by @shulaoda - remove dead LazyCompilationContext::is_lazy_module method (#10128) by @shulaoda - remove dead BuildDiagnostic::downcast_ref method (#10127) by @shulaoda - deps: update dependency vite-plus to v0.2.2 (#10084) by @renovate[bot] - deps: update rust crate oxc_sourcemap to v8.1.0 (#10122) by @renovate[bot] - deps: update crate-ci/typos action to v1.48.0 (#10124) by @renovate[bot] - enable more clippy restriction lints (#10114) by @Boshen - deps: update rust dependencies (#10100) by @Boshen - deps: update oxc resolver to v11.23.0 (#10083) by @renovate[bot] ###◀️ Revert - Revert "chore(deps): revert vite-plus to v0.2.1" (#10157) by @h-a-n-a - "fix(hmr): fall back to full reload when a changed module is not registered as executed (#10132)" (#10151) by @shulaoda ### ❤️ New Contributors * @V1OL3TF0X made their first contribution in [#9271](#9271) Co-authored-by: shulaoda <[email protected]>

What
This PR splits the statement eval analyzer result into two separate answers:
StmtEvalFlagsStmtInfo::side_effects()continues to carry only the tree-shaking flags.EcmaViewMeta::ExecutionOrderSensitivenow comes fromStmtEvalFacts::is_order_sensitive(), which combines unknown runtime side effects with order-sensitive reasons such as global reads and pure annotations.The cross-module optimization pass still re-runs the analyzer, but it consumes only
tree_shaking_flags()because that pass mutates removal-related metadata, not module execution-order metadata.Why
Rolldown needs to answer two different questions:
Keeping both answers in the same public bitset makes later order-sensitive facts look like tree-shaking side effects. That can affect chunk dependency edges or removal decisions for the wrong reason.
This PR is intended as a refactor that keeps existing behavior while making those two answers explicit.
Tests
cargo test -p rolldown stmt_eval_analyzer --libcargo check -p rolldown