fix: eliminate unreachable dynamic entry by IWANABETHATGUY · Pull Request #7356 · rolldown/rolldown

IWANABETHATGUY · 2025-12-06T14:27:18Z

IWANABETHATGUY · 2025-12-06T14:27:34Z

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netlify · 2025-12-06T14:28:15Z

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github-actions · 2025-12-06T14:44:05Z

Benchmarks Rust

target: main(28930b4)
pr: 12-05-fix_3403(411197a)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.00     65.9±1.62ms        ? ?/sec    1.09     71.7±2.30ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.00     72.3±1.74ms        ? ?/sec    1.07     77.2±2.29ms        ? ?/sec
bundle/bundle@rome_ts                                        1.00    108.2±1.80ms        ? ?/sec    1.03    111.0±2.05ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.00    121.7±1.74ms        ? ?/sec    1.03    124.8±2.84ms        ? ?/sec
bundle/bundle@threejs                                        1.01     40.5±2.50ms        ? ?/sec    1.00     40.0±0.80ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.00     43.5±1.12ms        ? ?/sec    1.01     43.9±0.77ms        ? ?/sec
bundle/bundle@threejs10x                                     1.00    398.7±5.40ms        ? ?/sec    1.02    405.8±9.12ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.00    455.8±4.55ms        ? ?/sec    1.02    466.6±8.07ms        ? ?/sec
scan/scan@rome_ts                                            1.00     84.7±1.69ms        ? ?/sec    1.04     88.4±2.25ms        ? ?/sec
scan/scan@threejs                                            1.01     29.0±1.95ms        ? ?/sec    1.00     28.8±0.48ms        ? ?/sec
scan/scan@threejs10x                                         1.00    294.8±4.66ms        ? ?/sec    1.02    299.3±4.32ms        ? ?/sec

Copilot

Pull request overview

This PR fixes issue #3403 by tracking dynamic import expressions that are inside "lazy paths" (e.g., inside PURE-annotated function callbacks) and preventing them from creating separate chunks during the bundling process. The fix involves tracking the AST address of dynamic import expressions and determining if they're unreachable for chunk splitting purposes when they appear inside side-effect-free function calls.

Key Changes:

Added DynamicImportPositionInfo struct to track both the statement index and AST address of dynamic import expressions
Extended cross-module optimization to detect when dynamic imports are inside lazy evaluation contexts (like PURE-annotated callbacks)
Modified entry point tracking to include the AST address alongside module and statement indices

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
crates/rolldown_common/src/types/import_record.rs	Introduces `DynamicImportPositionInfo` struct and replaces `related_stmt_info_idx` with `dynamic_import_info` field in `ImportRecord` to track both statement index and AST address
crates/rolldown_common/src/types/entry_point.rs	Extends `related_stmt_infos` tuple to include `Address` for tracking import expression locations
crates/rolldown_common/src/lib.rs	Exports new `DynamicImportPositionInfo` type
crates/rolldown/src/stages/link_stage/cross_module_optimization.rs	Implements logic to detect unreachable dynamic imports inside lazy paths, adds visitor tracking with `visit_path` and `is_lazy_path_from_first_lazy_node` helper function
crates/rolldown/src/stages/link_stage/tree_shaking/include_statements.rs	Updates `include_statements` to accept and use unreachable import expression addresses when determining if dynamic entries are alive
crates/rolldown/src/stages/link_stage/mod.rs	Threads unreachable addresses from cross-module optimization to statement inclusion
crates/rolldown/src/types/scan_stage_cache.rs	Updates tuple destructuring to handle new `Address` field in `related_stmt_infos`
crates/rolldown/src/module_loader/module_loader.rs	Updates dynamic import entry tracking to use new `dynamic_import_info` structure instead of `related_stmt_info_idx`
crates/rolldown/src/module_finalizers/mod.rs	Adds defensive checks when rewriting import expressions to handle cases where chunks may not exist for unreachable imports
crates/rolldown/src/ast_scanner/mod.rs	Updates `add_import_record` to accept `import_expression_address` parameter and construct `DynamicImportPositionInfo` when present
crates/rolldown/src/ast_scanner/impl_visit.rs	Passes import expression address when scanning dynamic imports
crates/rolldown/src/ast_scanner/new_url.rs	Updates `add_import_record` call to pass `None` for import expression address
crates/rolldown/src/ast_scanner/hmr.rs	Updates `add_import_record` calls to pass `None` for import expression address
crates/rolldown/tests/rolldown/issues/3403/*	Adds test case demonstrating the fix - dynamic import inside PURE callback no longer creates separate chunk
crates/rolldown/tests/rolldown/optimization/inline_empty_function_call/basic/artifacts.snap	Updates snapshot showing that unreachable module no longer generates a chunk
crates/rolldown/tests/snapshots/integration_rolldown__filename_with_hash.snap	Updates hash snapshot with new test case

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