fix: preserve name for parenthesized anonymous default exports and arrow functions with keepNames #7159

Copilot · 2025-11-20T14:39:14Z

Summary

Fixed the issue where __name() calls are not generated for anonymous default export functions/classes that are wrapped with parentheses when output.keepNames is enabled.

Changes Made

1. Scanner (ast_scanner/impl_visit.rs)

Added visit_export_default_declaration visitor to detect parenthesized anonymous function/class default exports and arrow functions
Mark statements with StmtInfoMeta::FnExpr or StmtInfoMeta::ClassExpr to ensure __name runtime helper is included in the chunk
Only process anonymous functions/classes (check id.is_none())
Add support for arrow functions

2. Finalizer (module_finalizers/mod.rs)

Modified remove_unused_top_level_stmt to detect parenthesized anonymous function/class expressions and arrow functions in export default statements
Schedule __name() calls to be inserted via keep_name_statement_to_insert mechanism (same pattern as FunctionDeclaration and ClassDeclaration)
Only process anonymous functions/classes and arrow functions

3. Tests

Added test case parenthesized_default_export with function, class, and arrow function cases
All existing keep_names tests continue to pass
Issue 7150 test continues to pass
Updated snapshot with new hash after test-rust run

Example Output

Before:

// Input: export default (function() {});
var dep_default = (function() {});
// Missing __name() call!

After:

// Input: export default (function() {});
var dep_default = (function() {});
__name(dep_default, "default");  // ✓ __name() call added!

Arrow functions:

// Input: export default (() => {});
var dep_arrow_default = (() => {});
__name(dep_arrow_default, "default");  // ✓ __name() call added!

Test Results

✅ All 7 keep_names tests pass
✅ Issue 7150 test passes
✅ Parenthesized default export test passes with function, class, and arrow function cases
✅ Snapshot updated with latest hash

Fixes #7150

Original prompt

This section details on the original issue you should resolve

<issue_title>[Bug]: the name property of an anonymous default export function that is wrapped with a parenthesis</issue_title>
<issue_description>### Reproduction link or steps

REPL

What is expected?

To have the __name(dep_default, "default"); call when output.keepNames is enabled.

What is actually happening?

__name(dep_default, "default"); is not output.

System Info
https://github.com/rolldown/rolldown/commit/6ca52aa9eb3f475cecfcb8c80ee9dd9425ca870c
Any additional comments?

The same issue exists with classes.

related #7150
</issue_description>

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

Fixes [Bug]: the name property of an anonymous default export function that is wrapped with a parenthesis #7154

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graphite-app · 2025-11-20T14:39:21Z

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IWANABETHATGUY · 2025-11-21T09:25:52Z

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github-actions · 2025-11-21T09:41:12Z

Benchmarks Rust

target: main(d643bd5)
pr: copilot/fix-anonymous-default-export-name(ecac645)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.03     66.6±2.22ms        ? ?/sec    1.00     64.5±2.22ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.04     72.7±1.89ms        ? ?/sec    1.00     69.8±1.34ms        ? ?/sec
bundle/bundle@rome_ts                                        1.02    109.0±1.85ms        ? ?/sec    1.00    107.2±1.89ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.02    122.0±2.37ms        ? ?/sec    1.00    119.7±1.98ms        ? ?/sec
bundle/bundle@threejs                                        1.00     39.3±1.46ms        ? ?/sec    1.00     39.3±0.90ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.00     42.8±0.73ms        ? ?/sec    1.00     42.9±1.01ms        ? ?/sec
bundle/bundle@threejs10x                                     1.01    394.5±4.03ms        ? ?/sec    1.00    390.6±7.36ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.02    456.1±4.82ms        ? ?/sec    1.00    447.7±3.97ms        ? ?/sec
scan/scan@rome_ts                                            1.00     85.3±1.91ms        ? ?/sec    1.00     85.4±1.84ms        ? ?/sec
scan/scan@threejs                                            1.00     28.8±1.91ms        ? ?/sec    1.01     29.0±1.97ms        ? ?/sec
scan/scan@threejs10x                                         1.01    297.2±5.68ms        ? ?/sec    1.00    294.3±4.82ms        ? ?/sec

Copilot

Pull Request Overview

This PR fixes a bug where parenthesized anonymous default exports don't generate __name() calls when keepNames is enabled, ensuring name preservation works correctly for expressions like export default (function() {}).

Key Changes

Added scanner support to detect parenthesized function/class expressions in default exports and mark them for __name helper inclusion
Enhanced finalizer to detect and schedule __name() insertion for parenthesized expressions in default export declarations
Added comprehensive test coverage for both parenthesized functions and classes, including anonymous and named variants

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
crates/rolldown/src/ast_scanner/impl_visit.rs	Added `visit_export_default_declaration` to detect and mark parenthesized function/class expressions for `__name` helper inclusion
crates/rolldown/src/module_finalizers/mod.rs	Enhanced default export handling to detect parenthesized expressions and schedule `__name()` call insertion
crates/rolldown/tests/rolldown/topics/keep_names/parenthesized_default_export/main.js	Test file that imports and verifies name preservation for different export variants
crates/rolldown/tests/rolldown/topics/keep_names/parenthesized_default_export/dep.js	Test case for parenthesized anonymous function default export
crates/rolldown/tests/rolldown/topics/keep_names/parenthesized_default_export/dep-class.js	Test case for parenthesized anonymous class default export
crates/rolldown/tests/rolldown/topics/keep_names/parenthesized_default_export/dep-named-default.js	Test case for parenthesized named function default export
crates/rolldown/tests/rolldown/topics/keep_names/parenthesized_default_export/artifacts.snap	Snapshot showing expected output with `__name()` calls
crates/rolldown/tests/rolldown/topics/keep_names/parenthesized_default_export/_config.json	Test configuration enabling `keepNames` option
crates/rolldown/tests/snapshots/integration_rolldown__filename_with_hash.snap	Updated snapshot with hash for new test

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crates/rolldown/src/module_finalizers/mod.rs

crates/rolldown/src/ast_scanner/impl_visit.rs

crates/rolldown/src/module_finalizers/mod.rs

crates/rolldown/tests/rolldown/topics/keep_names/parenthesized_default_export/dep-class.js

crates/rolldown/tests/rolldown/topics/keep_names/parenthesized_default_export/dep.js

crates/rolldown/src/ast_scanner/impl_visit.rs

crates/rolldown/src/module_finalizers/mod.rs

IWANABETHATGUY · 2025-11-21T11:09:05Z

@copilot, you should also check the arrow function.

Copilot · 2025-11-21T11:15:24Z

@copilot, you should also check the arrow function.

Added arrow function support in commit 9f7706b with test coverage for export default (() => {})

IWANABETHATGUY · 2025-11-22T14:21:02Z

@copilot update snapshot

Copilot · 2025-11-22T14:25:54Z

@copilot update snapshot

The snapshot is already up to date. The test passes successfully and the artifacts.snap file contains the correct output for all test cases (anonymous function, class, arrow function, and named function).

sapphi-red · 2025-11-23T06:31:44Z

@copilot update snapshot by just test-rust

Copilot · 2025-11-23T06:37:13Z

@copilot update snapshot by just test-rust

Updated snapshot in commit fc12918. The filename hash changed from main-Du06d7rC.js to main-4opC75UP.js due to the arrow function support additions.

Co-authored-by: IWANABETHATGUY <[email protected]>

- Add scanner support to detect parenthesized anonymous function/class default exports - Mark statements with StmtInfoMeta to ensure __name runtime helper is included - Add finalizer support to generate __name() calls for parenthesized exports - Add test cases for both function and class parenthesized default exports Co-authored-by: IWANABETHATGUY <[email protected]>

Co-authored-by: Copilot <[email protected]> Signed-off-by: IWANABETHATGUY <[email protected]>

…y checks - Add arrow function support in scanner and finalizer - Only process anonymous functions/classes (add is_none() checks) - Remove commented-out code from dep.js - Add test case for arrow function default export Co-authored-by: IWANABETHATGUY <[email protected]>

Co-authored-by: sapphi-red <[email protected]>

@shulaoda

## [1.0.0-beta.52] - 2025-11-26 💥 Breaking Change - Change `output.generatedCode.profilerNames` default to `false` 🔧 Vite-Style TypeScript Configuration - Rolldown now supports Vite-style automatic tsconfig resolution. Use `tsconfig: true` to enable auto-discovery mode where each module finds its nearest `tsconfig.json`. See more details [here](https://rolldown.rs/options/tsconfig) ⚙️ Upgraded to oxc v0.99.0 - Add `TSGlobalDeclaration` type - More details: https://github.com/oxc-project/oxc/releases/tag/crates_v0.99.0 ### 💥 BREAKING CHANGES - change `output.generatedCode.profilerNames` default to false (#7139) by @Copilot ### 🚀 Features - support vite-style tsconfig resolution (#6873) by @shulaoda - rolldown: oxc v0.99.0 (#7165) by @camc314 - browser: export `plugins` (#7210) by @sxzz - rolldown_plugin_vite_css_post: add `inline` parameter to `cssMinify` callback (#7191) by @shulaoda - rolldown_plugin_vite_build_import_analysis: implement `render_chunk` to replace `__VITE_IS_MODERN__` flag (#7178) by @shulaoda - rolldown_plugin_utils: optimize SVG data URL encoding (#7156) by @shulaoda - dev: replace `DevEngine::hasLatestBuildOutput` with `DevEngine::getBundleState` (#7145) by @sapphi-red - rolldown_plugin_vite_asset_import_meta_url: support `@vite-ignore` comment (#7141) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: implement static URL processing (#7140) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: align `asset_resolver` logic (#7137) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: align `try_fs_resolve` logic (#7136) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: validate relative paths (#7120) by @shulaoda - export `viteAssetImportMetaUrlPlugin` and add dynamic URL tests (#7119) by @shulaoda ### 🐛 Bug Fixes - watch overwrite rename event on linux (#7201) by @sapphi-red - preserve name for parenthesized anonymous default exports and arrow functions with keepNames (#7159) by @Copilot - rolldown_plugin_vite_html: add missing async attribute for inlined entry scripts (#7202) by @shulaoda - respect target setting in DCE to prevent modern syntax generation (#7128) by @Copilot - rolldown_plugin_vite_html: add semicolon to import statement in CSS removal (#7200) by @shulaoda - rolldown_plugin_vite_html: use correct CSS asset filename in HTML injection (#7199) by @shulaoda - rolldown_plugin_vite_css_post: handle scoped package names in lib CSS filename (#7198) by @shulaoda - rolldown_plugin_vite_html: use patched `html5gum` with correct span tracking (#7193) by @shulaoda - rolldown_plugin_vite_html: handle HTML strings in script tags correctly (#7192) by @shulaoda - handle JSON import namespace property access correctly (#7190) by @IWANABETHATGUY - only include runtime helpers from included modules (#7183) by @IWANABETHATGUY - rolldown_plugin_vite_html: normalize paths to use forward slashes in `original_file_name` (#7175) by @shulaoda - rolldown_plugin_vite_css_post: use `filename` instead of `reference_id` for imported assets (#7174) by @shulaoda - rolldown_plugin_vite_css_post: correct regex escaping in pure CSS chunk pruning (#7173) by @shulaoda - rolldown_plugin_vite_html: use correct dependency path for modulepreload links (#7172) by @shulaoda - update cur_stmt_index when processing top level statements (#7157) by @IWANABETHATGUY - rolldown_plugin_utils: strip leading character from public asset URL (#7170) by @shulaoda - rolldown_plugin_vite_html: use correct `public_base` for `html_result_map` key (#7169) by @shulaoda - rolldown_plugin_utils: correct runtime handling and escape single quotes in asset paths (#7168) by @shulaoda - rolldown_plugin_utils: prevent data race in `file_to_url` cache (#7166) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: correct glob pattern and query string handling in dynamic URLs (#7162) by @shulaoda - rolldown_plugin_vite_css_post: use correct start position in magic string updates (#7158) by @shulaoda - data race in `FileEmitter::emit_file` causing duplicate asset emissions (#7164) by @shulaoda - dev: watch files even if the build failed (#7149) by @sapphi-red - rolldown_plugin_utils: always use base64 encoding for data URLs (#7148) by @shulaoda - preserve "default" name for anonymous default exports with keepNames (#7151) by @Copilot - correctly handle cjs json module as entry point (#7147) by @IWANABETHATGUY - rolldown_plugin_utils: correct `reference_id` parsing in `render_asset_url_in_js` (#7143) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: exclude quotes from URL span (#7142) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: use template literal for glob result indexing (#7134) by @shulaoda - tree shake unused dynamic entry when `inlineDynamicImports` is enabled (#7129) by @IWANABETHATGUY - correct return value of `parse` / `parseSync` functions (#7127) by @sapphi-red ### 🚜 Refactor - rolldown_plugin_vite_transform: use `oxc_resolver` for tsconfig discovery (#7220) by @shulaoda - rolldown_plugin_vite_resolve: use `resolve_file` for tsconfig discovery (#7216) by @shulaoda - rolldown_plugin_utils: remove redundant `ViteMetadata::get_or_insert_default()` (#7189) by @shulaoda - rolldown_plugin_utils: simplify `ViteMetadata::get()` to always return a value (#7188) by @shulaoda - rolldown_utils: add `guess_mime_skip_utf8_check` for binary assets (#7161) by @shulaoda - rolldown_plugin_utils: extract asset URL parsing into `AssetUrlIter` (#7144) by @shulaoda - store pattern name in FilenameTemplate (#7132) by @IWANABETHATGUY ### 📚 Documentation - tsconfig: document auto-discovery mode and improve structure (#7228) by @shulaoda - add plugin hook filter compatibility and fallback guide (#7138) by @Copilot - update top level navigation (#7092) by @mdong1909 ### 🧪 Testing - add tsconfig include/exclude/files matching test cases (#6899) by @shulaoda - vite-tests: run `playwright install` in case playwright binary is missing (#7226) by @sapphi-red - watch: close watcher when an error occured in the test cases (#7225) by @sapphi-red - watch: reject `waitBuildFinished` if `ERROR` event occurs (#7224) by @sapphi-red ### ⚙️ Miscellaneous Tasks - example: revert accidental changes to basic-typescript (#7227) by @shulaoda - deps: update oxc apps (#7212) by @renovate[bot] - deps: update rust crates (#7204) by @renovate[bot] - deps: update `oxc_resolver_napi` to 11.14.0 (#7217) by @shulaoda - deps: update oxc_resolver (#6909) by @shulaoda - deps: update dependency glob to v13 (#7208) by @renovate[bot] - deps: update actions/checkout action to v6 (#7207) by @renovate[bot] - deps: update npm packages (#7206) by @renovate[bot] - deps: update github-actions (#7205) by @renovate[bot] - add missing status code comment (#7185) by @iiio2 - deps: update dependency oxlint-tsgolint to v0.8.1 (#7197) by @renovate[bot] - rust: add more tracing log for hmr + dev logic (#7179) by @hyf0 - deps: update dependency oxlint-tsgolint to v0.8.0 (#7167) by @renovate[bot] - deps: update dependency oxlint-tsgolint to v0.7.3 (#7133) by @renovate[bot] - merge similar inlineDynamicImports test case (#7131) by @IWANABETHATGUY - deps: update `rolldown-plugin-dts` to 0.18.0 (#7125) by @shulaoda Co-authored-by: shulaoda <[email protected]>

Copilot AI assigned Copilot and IWANABETHATGUY Nov 20, 2025

Copilot started work on behalf of IWANABETHATGUY November 20, 2025 14:39 View session

Copilot AI changed the title ~~[WIP] Fix name property of anonymous default export function~~ Fix: preserve name for parenthesized anonymous default exports with keepNames Nov 20, 2025

Copilot AI requested a review from IWANABETHATGUY November 20, 2025 15:16

Copilot finished work on behalf of IWANABETHATGUY November 20, 2025 15:16

IWANABETHATGUY force-pushed the copilot/fix-anonymous-default-export-name branch 2 times, most recently from c714310 to 9291492 Compare November 21, 2025 09:25

IWANABETHATGUY force-pushed the copilot/fix-anonymous-default-export-name branch from b8d6d4c to 786d376 Compare November 21, 2025 09:57

IWANABETHATGUY marked this pull request as ready for review November 21, 2025 10:01

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IWANABETHATGUY changed the title ~~Fix: preserve name for parenthesized anonymous default exports with keepNames~~ fix: preserve name for parenthesized anonymous default exports with keepNames Nov 21, 2025

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Copilot AI changed the title ~~fix: preserve name for parenthesized anonymous default exports with keepNames~~ fix: preserve name for parenthesized anonymous default exports and arrow functions with keepNames Nov 21, 2025

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Copilot AI and others added 10 commits November 23, 2025 22:58

Add test case for parenthesized default export with keepNames

68e67e9

Co-authored-by: IWANABETHATGUY <[email protected]>

[autofix.ci] apply automated fixes

f2f8bb9

Update crates/rolldown/src/module_finalizers/mod.rs

fd8abf5

Co-authored-by: Copilot <[email protected]> Signed-off-by: IWANABETHATGUY <[email protected]>

Update crates/rolldown/src/ast_scanner/impl_visit.rs

4fdafa8

Co-authored-by: Copilot <[email protected]> Signed-off-by: IWANABETHATGUY <[email protected]>

Update crates/rolldown/src/ast_scanner/impl_visit.rs

e83d653

Co-authored-by: Copilot <[email protected]> Signed-off-by: IWANABETHATGUY <[email protected]>

Update crates/rolldown/src/module_finalizers/mod.rs

a9a2fe9

Co-authored-by: Copilot <[email protected]> Signed-off-by: IWANABETHATGUY <[email protected]>

[autofix.ci] apply automated fixes

1e05a60

Update snapshot after running just test-rust

ecac645

Co-authored-by: sapphi-red <[email protected]>

sapphi-red force-pushed the copilot/fix-anonymous-default-export-name branch from 0c36034 to ecac645 Compare November 23, 2025 13:58

sapphi-red merged commit 98e88c4 into main Nov 23, 2025
28 checks passed

sapphi-red deleted the copilot/fix-anonymous-default-export-name branch November 23, 2025 14:12

This was referenced Nov 26, 2025

release: v1.0.0-beta.52 #7223

Closed

release: v1.0.0-beta.52 #7229

Merged

fix: preserve name for parenthesized anonymous default exports and arrow functions with keepNames #7159

fix: preserve name for parenthesized anonymous default exports and arrow functions with keepNames #7159

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Summary

Changes Made

1. Scanner (ast_scanner/impl_visit.rs)

2. Finalizer (module_finalizers/mod.rs)

3. Tests

Example Output

Test Results

What is expected?

What is actually happening?

System Info

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