fix: duplicate default export when using both import and require #6764

Copilot · 2025-10-30T04:04:37Z

Summary

Fixed duplicate default export bug when using both import and require for the same module.

Changes Made

Technical Details

The fix modifies crates/rolldown/src/utils/chunk/render_chunk_exports.rs to detect when we're processing an entry point with a CJS wrapper and filter out any "default" exports from the export_items list, since render_wrapped_entry_chunk already handles the default export. Other exports are preserved for cross-chunk references.

Original prompt

This section details on the original issue you should resolve

<issue_title>[Bug]: Duplicate default export on import + require usage</issue_title>
<issue_description>### Reproduction link or steps

Have some input code like this :
// Require
const required = require('./file.json')

// Dynamic Import
const dynamicRes = await import('./file.json')
Reproduction : https://github.com/Gugustinette/rolldown-import-require-repro

What is expected?

This is what one of the input file should look I guess :
import { require_file } from "./file-DuStti8x.js";

export default require_file();
What is actually happening?

This is how it looks right now :
import { require_file } from "./file-DuStti8x.js";

export default require_file();

export { file_default as default };
There are 2 default exports, which causes an error whenever running/importing associated modules.

System Info
System:
    OS: macOS 14.5
    CPU: (8) arm64 Apple M1 Pro
    Memory: 111.30 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.2.0 - /opt/homebrew/bin/node
    Yarn: 1.22.17 - /usr/local/bin/yarn
    npm: 11.5.2 - /opt/homebrew/bin/npm
    pnpm: 10.8.1 - /opt/homebrew/bin/pnpm
    bun: 1.2.19 - /Users/augustinmercier/.bun/bin/bun
    Deno: 2.3.3 - /Users/augustinmercier/.deno/bin/deno
    Watchman: 2025.05.26.00 - /opt/homebrew/bin/watchman
  Browsers:
    Chrome: 141.0.7390.66
    Firefox: 121.0
    Safari: 17.5
  npmPackages:
    rolldown: ^1.0.0-beta.43 => 1.0.0-beta.43
Any additional comments?

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes [Bug]: Duplicate default export on import + require usage #6571

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

graphite-app · 2025-10-30T04:04:43Z

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netlify · 2025-10-30T04:05:26Z

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

IWANABETHATGUY · 2025-10-30T04:53:52Z

@copilot fix the CI error

Copilot · 2025-10-30T05:00:37Z

@copilot fix the CI error

Fixed CI error by committing the updated snapshot hash. The hash changed because the test file was modified to use assert statements. Commit 95455fd

github-actions · 2025-10-30T05:03:32Z

Benchmarks Rust

target: main(d460188)
pr: copilot/fix-duplicate-default-export(e0d4b3b)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.00     66.6±2.28ms        ? ?/sec    1.02     67.7±2.07ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.00     73.1±2.10ms        ? ?/sec    1.05     76.5±4.04ms        ? ?/sec
bundle/bundle@rome_ts                                        1.02    112.3±3.11ms        ? ?/sec    1.00    109.8±1.81ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.00    122.3±1.65ms        ? ?/sec    1.01    123.7±2.58ms        ? ?/sec
bundle/bundle@threejs                                        1.00     41.3±2.39ms        ? ?/sec    1.00     41.2±0.89ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.00     43.8±0.61ms        ? ?/sec    1.01     44.2±0.84ms        ? ?/sec
bundle/bundle@threejs10x                                     1.02    409.2±7.34ms        ? ?/sec    1.00    401.9±6.17ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.00    465.9±6.27ms        ? ?/sec    1.01    469.4±6.70ms        ? ?/sec
scan/scan@rome_ts                                            1.00     87.3±1.55ms        ? ?/sec    1.01     87.9±1.79ms        ? ?/sec
scan/scan@threejs                                            1.00     29.3±0.49ms        ? ?/sec    1.01     29.6±0.49ms        ? ?/sec
scan/scan@threejs10x                                         1.00    302.1±3.78ms        ? ?/sec    1.01    304.7±5.05ms        ? ?/sec

shulaoda · 2025-10-30T06:34:00Z

Merge activity

Oct 30, 6:33 AM UTC: The merge label 'graphite: merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Oct 30, 6:34 AM UTC: shulaoda added this pull request to the Graphite merge queue.

## Summary Fixed duplicate default export bug when using both `import` and `require` for the same module. ### Changes Made - [x] Understand the issue: duplicate default exports when both `import` and `require` are used for the same module - [x] Create test case to reproduce the issue (`crates/rolldown/tests/rolldown/issues/duplicate_default_export/`) - [x] Analyze the root cause in the export rendering logic - [x] Fix the logic in `render_chunk_exports` to filter out "default" from export_items when rendering exports for CJS wrapped entry points - [x] Verify the fix with the test case - no more duplicate default exports - [x] Run existing tests to ensure no regressions (all 603 integration tests + all unit tests pass) - [x] Apply code formatting (rustfmt) - [x] Code review completed - [x] Update test to use assert instead of console.log - [x] Update snapshot hash after test modification - [x] Final verification complete ### Technical Details The fix modifies `crates/rolldown/src/utils/chunk/render_chunk_exports.rs` to detect when we're processing an entry point with a CJS wrapper and filter out any "default" exports from the export_items list, since `render_wrapped_entry_chunk` already handles the default export. Other exports are preserved for cross-chunk references.  <details> <summary>Original prompt</summary> > > ---- > > *This section details on the original issue you should resolve* > > <issue_title>[Bug]: Duplicate default export on `import` + `require` usage</issue_title> > <issue_description>### Reproduction link or steps > > Have some input code like this : > > ```ts > // Require > const required = require('./file.json') > > // Dynamic Import > const dynamicRes = await import('./file.json') > ``` > > Reproduction : https://github.com/Gugustinette/rolldown-import-require-repro > > ### What is expected? > > This is what one of the input file should look I guess : > > ```js > import { require_file } from "./file-DuStti8x.js"; > > export default require_file(); > ``` > > ### What is actually happening? > > This is how it looks right now : > > ```js > import { require_file } from "./file-DuStti8x.js"; > > export default require_file(); > > export { file_default as default }; > ``` > > There are 2 default exports, which causes an error whenever running/importing associated modules. > > ### System Info > > ```Shell > System: > OS: macOS 14.5 > CPU: (8) arm64 Apple M1 Pro > Memory: 111.30 MB / 16.00 GB > Shell: 5.9 - /bin/zsh > Binaries: > Node: 24.2.0 - /opt/homebrew/bin/node > Yarn: 1.22.17 - /usr/local/bin/yarn > npm: 11.5.2 - /opt/homebrew/bin/npm > pnpm: 10.8.1 - /opt/homebrew/bin/pnpm > bun: 1.2.19 - /Users/augustinmercier/.bun/bin/bun > Deno: 2.3.3 - /Users/augustinmercier/.deno/bin/deno > Watchman: 2025.05.26.00 - /opt/homebrew/bin/watchman > Browsers: > Chrome: 141.0.7390.66 > Firefox: 121.0 > Safari: 17.5 > npmPackages: > rolldown: ^1.0.0-beta.43 => 1.0.0-beta.43 > ``` > > ### Any additional comments? > > _No response_</issue_description> > > ## Comments on the Issue (you are @copilot in this section) > > <comments> > </comments> > </details> - Fixes #6571  --- 💬 We'd love your input! Share your thoughts on Copilot coding agent in our [2 minute survey](https://gh.io/copilot-coding-agent-survey).

@sapphi-red

## [1.0.0-beta.46] - 2025-11-03 ### 💥 BREAKING CHANGES - default `preserveEntrySignatures` to `'exports-only'` to align with Rollup (#6723) by @Copilot ### 🚀 Features - link to docs for commonjs prefer_builtin_feature diagnostic (#6793) by @sapphi-red - rolldown_plugin_build_import_analysis: align partial logic (#6789) by @shulaoda - improve `EVAL` warning message (#6776) by @sapphi-red - rolldown: oxc v0.96.0 (#6774) by @Boshen - rolldown_plugin_build_import_analysis: align partial logic (#6773) by @shulaoda - skip `__toESM` when not needed to reduce output size (#6751) by @Copilot - improve `EMPTY_IMPORT_META` warning message (#6761) by @sapphi-red - rolldown_plugin_build_import_analysis: align no preload logic (#6762) by @shulaoda - rolldown_plugin_vite_css_post: align `RemovedPureCSSFilesCache` logic (#6745) by @shulaoda - rolldown_plugin_build_import_analysis: initialize `generateBundle` logic (#6744) by @shulaoda - experimental: introduce `freeExternalMemory` to free external memory immediately (#6721) by @hyf0 ### 🐛 Bug Fixes - plugins: wrap replacePlugin with makeBuiltinPluginCallable (#6782) by @huang-julien - debug: make sure `this.resolve` is also tracked under corresponding session (#6798) by @hyf0 - legal comments above directives are not preserved (#6787) by @shulaoda - panic when rendering exports to other chunks (#6765) by @Copilot - transform/inject: escape special characters in import source (#6778) by @Copilot - handle default exports from CJS modules correctly (#6767) by @IWANABETHATGUY - rolldown_plugin_build_import_analysis: correct aligned logic (#6768) by @shulaoda - duplicate default export when using both import and require (#6764) by @Copilot - handle arbitrary module namespace identifiers in `preserveEntrySignatures: 'allow-extension'` (#6753) by @Copilot - TypeError when loading CJS files after bundling mixed CJS+TS project (#6743) by @IWANABETHATGUY - add warnings for import.meta.dirname/filename/url in UMD and IIFE formats (#6747) by @Copilot - rolldown_plugin_manifest: should keep `names` field (#6742) by @shulaoda - legal comments above import statements are not preserved (#6717) by @shulaoda - remove redundant node check in dynamic entry graph construction (#6730) by @IWANABETHATGUY ### 🚜 Refactor - remove unnecessary `#[napi(gettter)]`, use function call directly (#6694) by @hyf0 - explain the reason if memory doesn't get dropped by `freeExternalMemory` (#6781) by @hyf0 - pre compute exports (#6755) by @IWANABETHATGUY - dev: receive an interface for DevRuntime rather than WebSocket directly (#6734) by @sapphi-red - dev: fix types for the runtime file and expose it properly (#6731) by @sapphi-red ### 📚 Documentation - fix magicstring credit (#6812) by @TheAlexLichter - in-depth/bundling-cjs: wrap some sections with caveats section (#6796) by @sapphi-red - in-depth/bundling-cjs: add "Ambiguous `default` import from CJS modules" section (#6795) by @sapphi-red - in-depth/bundling-cjs: make `esmExternalRequirePlugin` link more prominent (#6792) by @sapphi-red - add explanation about direct eval (#6775) by @sapphi-red - add "Non-ESM Output Formats" page (#6760) by @sapphi-red - use oxc for benchmark comparison in native magic string doc (#6740) by @sapphi-red - polish `cleanDir` option (#6741) by @hyf0 - fix image in native magic string doc (#6739) by @sapphi-red - update description about `attachDebugInfo: 'none'` (#6738) by @IWANABETHATGUY - add warning about cleanDir behavior with multiple configs (#6735) by @Copilot ### 🧪 Testing - skip paths function test (#6771) by @IWANABETHATGUY - rust/dev: add test about recover from initial build error (#6567) by @hyf0 ### ⚙️ Miscellaneous Tasks - correct prepare release binding file (#6817) by @shulaoda - deps: update github-actions (#6806) by @renovate[bot] - deps: lock file maintenance npm packages (#6814) by @renovate[bot] - use correct node version (#6809) by @shulaoda - deps: lock file maintenance rust crates (#6815) by @renovate[bot] - deps: update npm packages (major) (#6813) by @renovate[bot] - deps: update dependency dprint-typescript to v0.95.12 (#6805) by @renovate[bot] - fix typo (#6801) by @iiio2 - fix typo in is_import_expr_ignored_by_comment method name (#6797) by @sapphi-red - deps: update crate-ci/typos action to v1.39.0 (#6794) by @renovate[bot] - deps: upgrade Rust to v1.91.0 and fix new clippy lints (#6785) by @Copilot - allow dprint to format `packages/rolldown/tests` except diagnostics directory (#6772) by @Copilot - deps: update dependency tsdown to v0.15.12 (#6759) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.17.3 (#6758) by @renovate[bot] - test/dev: collect multiple build outputs for each step (#6736) by @hyf0 - rolldown: change the NAPI-RS binding file to the cjs (#6688) by @Brooooooklyn - test: automatically run extra test with `preserve_entry_signatures: 'allow-extension'` (#6727) by @Copilot - deps: update dependency rolldown-plugin-dts to v0.17.2 (#6732) by @renovate[bot] - fix node validation (#6728) by @shulaoda - deps: lock file maintenance rust crates (#6636) by @renovate[bot] - deps: update dependency tsdown to v0.15.11 (#6725) by @renovate[bot] ### ❤️ New Contributors * @huang-julien made their first contribution in [#6782](#6782) Co-authored-by: shulaoda <[email protected]>

Copilot AI assigned Copilot and IWANABETHATGUY Oct 30, 2025

Copilot started work on behalf of IWANABETHATGUY October 30, 2025 04:04 View session

Copilot AI changed the title ~~[WIP] Fix duplicate default export issue with import and require~~ Fix duplicate default export when using both import and require Oct 30, 2025

Copilot AI requested a review from IWANABETHATGUY October 30, 2025 04:27

Copilot finished work on behalf of IWANABETHATGUY October 30, 2025 04:27

IWANABETHATGUY reviewed Oct 30, 2025

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crates/rolldown/tests/rolldown/issues/duplicate_default_export/main.js Outdated Show resolved Hide resolved

Copilot started work on behalf of IWANABETHATGUY October 30, 2025 04:43 View session

Copilot AI requested a review from IWANABETHATGUY October 30, 2025 04:47

Copilot finished work on behalf of IWANABETHATGUY October 30, 2025 04:47

Copilot started work on behalf of IWANABETHATGUY October 30, 2025 04:54 View session

Copilot finished work on behalf of IWANABETHATGUY October 30, 2025 05:01

IWANABETHATGUY marked this pull request as ready for review October 30, 2025 05:03

IWANABETHATGUY force-pushed the copilot/fix-duplicate-default-export branch from 95455fd to 2d03fa5 Compare October 30, 2025 05:03

IWANABETHATGUY changed the title ~~Fix duplicate default export when using both import and require~~ fix: duplicate default export when using both import and require Oct 30, 2025

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IWANABETHATGUY requested review from hyf0 and shulaoda October 30, 2025 05:08

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IWANABETHATGUY enabled auto-merge (squash) October 30, 2025 06:30

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shulaoda added the graphite: merge label Oct 30, 2025

graphite-app bot force-pushed the copilot/fix-duplicate-default-export branch from 2d03fa5 to e0d4b3b Compare October 30, 2025 06:34

IWANABETHATGUY merged commit 118bfa0 into main Oct 30, 2025
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IWANABETHATGUY deleted the copilot/fix-duplicate-default-export branch October 30, 2025 06:48

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release: v1.0.0-beta.46 #6818

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fix: duplicate default export when using both import and require #6764

fix: duplicate default export when using both import and require #6764

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fix: duplicate default export when using both import and require #6764

fix: duplicate default export when using both import and require #6764

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Summary

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System Info

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