## Summary
This PR fixes a bug in Bun's bundler where cyclic imports with async
dependencies would produce invalid JavaScript with syntax errors.
## Problem
When modules have cyclic imports and one uses top-level await, the
bundler wasn't properly marking all modules in the cycle as async. This
resulted in non-async wrapper functions containing `await` statements,
causing syntax errors like:
```
error: "await" can only be used inside an "async" function
```
## Solution
The fix matches esbuild's approach by calling `validateTLA` for all
files before `scanImportsAndExports` begins. This ensures async status
is properly propagated through import chains before dependency
resolution.
Key changes:
1. Added a new phase that validates top-level await for all parsed
JavaScript files before import/export scanning
2. This matches esbuild's `finishScan` function which processes all
files in source index order
3. Ensures the `is_async_or_has_async_dependency` flag is properly set
for all modules in cyclic import chains
## Test Plan
- Fixed the reproduction case provided in
`/Users/dylan/clones/bun-esm-bug`
- All existing bundler tests pass, including
`test/bundler/esbuild/default.test.ts`
- The bundled output now correctly generates async wrapper functions
when needed
fixes#21113🤖 Generated with [Claude Code](https://claude.ai/code)
---------
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
7a47c945aa