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fix: don't classify await in a strict-mode function as top-level await#9987

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06-26-fix_don_t_classify_await_in_a_strict-mode_function_as_top-level_await
Jun 28, 2026
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fix: don't classify await in a strict-mode function as top-level await#9987
graphite-app[bot] merged 1 commit into
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06-26-fix_don_t_classify_await_in_a_strict-mode_function_as_top-level_await

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@shulaoda

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What this solves

is_valid_tla_scope accepted any scope whose flags intersected Top | StrictMode. oxc marks a class scope as exactly StrictMode (so a class computed key like class T { [await x]() {} } counts as top-level), but it also adds StrictMode to a function or arrow that carries its own "use strict" directive (Function | StrictMode). So await inside such a function was misclassified as top-level await.

For a non-ESM output format this produced a spurious build error:

// bundled to cjs
export async function f() {
  'use strict'
  await Promise.resolve() // "Top-level await is currently not supported with the 'cjs' output format"
}

even though the await is inside an async function and is valid for any output format.

The fix

Use flag.is_top() || flag.is_block(). is_block() is is_empty() || self == StrictMode, so it still covers block scopes and class scopes, while a strict function (Function | StrictMode) is neither top nor block and is correctly rejected.

Tests

Added tests/rolldown/misc/use_strict/await_in_strict_function_is_not_tla: a cjs build of an async function with a "use strict" directive and an inner await. It fails with the spurious TLA error without the fix and passes with it, and the full integration suite passes with no other snapshot changes.

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codspeed-hq Bot commented Jun 26, 2026

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Merging this PR will not alter performance

✅ 7 untouched benchmarks
⏩ 10 skipped benchmarks1


Comparing 06-26-fix_don_t_classify_await_in_a_strict-mode_function_as_top-level_await (f44da30) with main (453d5bb)

Open in CodSpeed

Footnotes

  1. 10 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.

shulaoda commented Jun 28, 2026

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Merge activity

  • Jun 28, 5:50 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.
  • Jun 28, 5:51 AM UTC: shulaoda added this pull request to the Graphite merge queue.
  • Jun 28, 5:56 AM UTC: Merged by the Graphite merge queue.

#9987)

### What this solves

`is_valid_tla_scope` accepted any scope whose flags intersected `Top | StrictMode`. oxc marks a class scope as exactly `StrictMode` (so a class computed key like `class T { [await x]() {} }` counts as top-level), but it also adds `StrictMode` to a function or arrow that carries its own `"use strict"` directive (`Function | StrictMode`). So `await` inside such a function was misclassified as top-level await.

For a non-ESM output format this produced a spurious build error:

```js
// bundled to cjs
export async function f() {
  'use strict'
  await Promise.resolve() // "Top-level await is currently not supported with the 'cjs' output format"
}
```

even though the `await` is inside an async function and is valid for any output format.

### The fix

Use `flag.is_top() || flag.is_block()`. `is_block()` is `is_empty() || self == StrictMode`, so it still covers block scopes and class scopes, while a strict function (`Function | StrictMode`) is neither top nor block and is correctly rejected.

### Tests

Added `tests/rolldown/misc/use_strict/await_in_strict_function_is_not_tla`: a cjs build of an async function with a `"use strict"` directive and an inner `await`. It fails with the spurious TLA error without the fix and passes with it, and the full integration suite passes with no other snapshot changes.
@graphite-app graphite-app Bot force-pushed the 06-26-fix_don_t_classify_await_in_a_strict-mode_function_as_top-level_await branch from f44da30 to 7026fd5 Compare June 28, 2026 05:52
@graphite-app graphite-app Bot merged commit 7026fd5 into main Jun 28, 2026
33 of 34 checks passed
@graphite-app graphite-app Bot deleted the 06-26-fix_don_t_classify_await_in_a_strict-mode_function_as_top-level_await branch June 28, 2026 05:56
@rolldown-guard rolldown-guard Bot mentioned this pull request Jul 1, 2026
shulaoda added a commit that referenced this pull request Jul 1, 2026
## [1.1.4] - 2026-07-01

### 🚀 Features

- disable `experimental.lazyBarrel` by default (#10071) by @shulaoda

### 🐛 Bug Fixes

- dev: disable lazy barrel in dev mode (#10060) by @shulaoda
- generate: keep full JSON interface under preserveModules namespa… (#10056) by @IWANABETHATGUY
- check finalize_other_specifiers in its own Debug attribute (#10032) by @shulaoda
- serialize the KeepAssign unused minify option as "keep_assign" (#10031) by @shulaoda
- keep fragments after the newline fragment in MagicString::last_line (#10023) by @shulaoda
- generate: undeclared JSON named exports under preserveModules (#10020) (#10027) by @IWANABETHATGUY
- deconflict: rename CJS-wrapped locals that shadow chunk-root bindings (#9921) by @IWANABETHATGUY
- rolldown: keep entry facade when a shared chunk holds another entry's module (#9997) by @hyf0
- treeshake: also bail JSON default split when the object escapes (#9996) by @IWANABETHATGUY
- don't classify await in a strict-mode function as top-level await (#9987) by @shulaoda
- avoid spurious leading newline in addon hooks (banner/footer/intro/outro) (#9989) by @shulaoda
- handle JSON default mutation bailouts (#9972) by @TheAlexLichter
- plugin: make lazy hook metadata enumerable (#9991) by @TheAlexLichter
- dev: make init errors in lazy-compiled modules catchable (#9981) by @h-a-n-a
- treeshake: keep computed-key side effects on namespace member access (#9986) by @shulaoda
- binding: validate replace plugin delimiters length instead of panicking (#9984) by @shulaoda
- reconstruct nested rest patterns in into_expression (#9980) by @IWANABETHATGUY
- reconstruct rest patterns as spread in into_expression (#9976) by @shulaoda
- preserve export keyword on multi-declarator exports under keepNames (#9974) by @shulaoda
- deterministically keep the shortest name for deduplicated assets (#9948) by @x1024
- treeshake: apply @__NO_SIDE_EFFECTS__ to cross-chunk namespace calls (#9960) by @IWANABETHATGUY

### 🚜 Refactor

- drop redundant program scope enter/leave in finalizer (#10049) by @shulaoda
- deconflict: extract collect_chunk_scope_captured_names (#10006) by @IWANABETHATGUY
- unify pre-scan multi-declarator split into one decision site (#9982) by @IWANABETHATGUY
- common: return bool from SymbolRef::is_not_reassigned (#9962) by @IWANABETHATGUY

### 📚 Documentation

- rolldown: remove outdated comment for removing parenthesized expression (#10062) by @Dunqing
- use GitHub-flavored alert for Etiquette note in contribution guide (#10012) by @IWANABETHATGUY
- replace: explain the delimiters left and right boundaries (#9985) by @shulaoda
- ast-mutation: remove stale Address Use section after pre-scan refactor (#9983) by @IWANABETHATGUY
- remove fathom (#9968) by @mdong1909
- contribution-guide: code-format main branch references (#9966) by @IWANABETHATGUY
- contribution-guide: fix stale REPL note and tidy wording (#9957) by @hyf0
- contribution-guide: clarify when to discuss before opening a PR (#9955) by @hyf0

### ⚡ Performance

- disable preserve_parens across all parse paths (#10057) by @Dunqing
- common: inline declared_symbols with SmallVec (#9920) by @IWANABETHATGUY
- common: pack TaggedSymbolRef into 8 bytes (#9919) by @IWANABETHATGUY
- sourcemap: skip newline scan on the no-sourcemap join fast path (#9936) by @Boshen

### 🧪 Testing

- dev: error in lazy module should be catchable (#9975) by @sapphi-red
- dev: reject unknown lazy compile modules (#9969) by @sapphi-red

### ⚙️ Miscellaneous Tasks

- deps: update actions/cache action to v6 (#10001) by @renovate[bot]
- trigger vite ecosystem-ci from PR comments (#10058) by @shulaoda
- deps: update napi to v3.10.0 (#10063) by @renovate[bot]
- remove unused From impl for RolldownLabelSpan (#10055) by @shulaoda
- remove dead Diagnostic::with_kind method (#10054) by @shulaoda
- remove unused StatementExt methods (#10053) by @shulaoda
- remove unused ExpressionExt methods (#10052) by @shulaoda
- remove commented-out re_export_all_names field (#10051) by @shulaoda
- deps: update pnpm to v11.9.0 (#10047) by @renovate[bot]
- remove the unused BindingGenerateHmrPatchReturn napi type (#10034) by @shulaoda
- remove the dead inline_entry_chunk_wrapping scaffolding (#10037) by @shulaoda
- deps: bump oxc_resolver to 11.22.0 (#10045) by @Boshen
- remove never-constructed MatchImportKind::_Ignore variant (#10041) by @shulaoda
- remove the unused ScheduledBuild napi struct (#10033) by @shulaoda
- remove dead compute_hmr_update_single method (#10040) by @shulaoda
- drop the redundant visited.insert in manual code splitting (#10038) by @shulaoda
- remove the dead output_assets vector in render_chunk_to_assets (#10036) by @shulaoda
- remove the unused From<String>/Display impls for BindingLogLevel (#10035) by @shulaoda
- deps: upgrade oxc to 0.138.0 and migrate to per-type AST construction (#10018) by @shulaoda
- deps: update rust crates (#9911) by @renovate[bot]
- deps: update test262 submodule for tests (#10016) by @rolldown-guard[bot]
- deps: update github actions (#9999) by @renovate[bot]
- deps: update npm packages (#10000) by @renovate[bot]

### ◀️ Revert

- "fix(plugin): make lazy hook metadata enumerable (#9991)" (#10005) by @shulaoda

### ❤️ New Contributors

* @x1024 made their first contribution in [#9948](#9948)

Co-authored-by: shulaoda <165626830+shulaoda@users.noreply.github.com>
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