## Implementation Complete: Add warning for top-level await usage
Successfully implemented warning for top-level await usage when the
target doesn't support it, following the same pattern as the existing
BigInt warning.
✅ **Successfully merged main branch and resolved all conflicts**
All changes have been merged with the latest main and all tests pass.
Ready for review and merge.
## Summary
- [x] Add `ES2022TopLevelAwait` feature to `oxc_compat` crate
- [x] Add `top_level_await` option to `ES2022Options`
- [x] Update `EnvOptions` to include `top_level_await` feature detection
- [x] Implement `enter_await_expression` handler in `ES2022` to emit
warning for top-level await
- [x] Add test cases to verify the warning is emitted correctly
- [x] Run tests to ensure everything works
- [x] Address review feedback: use `ctx.scoping().root_scope_id()` to
check for top-level
- [x] Add feature to `es-features.js` for proper tracking
- [x] Add test case for nested block with await (confirms current
implementation is correct)
- [x] **Merge main branch and resolve all conflicts** ✨
## Test Results
All tests pass successfully:
- ✅ oxc_transformer: 30 unit tests + 3 integration tests (es_target)
- ✅ oxc_compat: 3 tests
- ✅ No clippy warnings
- ✅ Successfully merged with latest main
## Resolved Conflicts
Merged with main and resolved conflicts in:
- `crates/oxc_compat/src/es_features.rs` - kept both
ES2020ArbitraryModuleNamespaceNames and ES2022TopLevelAwait features
- `crates/oxc_transformer/src/lib.rs` - kept both import/export
specifier methods and await expression method
- `crates/oxc_transformer/tests/integrations/es_target.rs` - kept both
test cases
- `crates/oxc_transformer/tests/integrations/snapshots/es_target.snap` -
updated test numbering to include both features
- `tasks/compat_data/data.json` - kept both
ArbitraryModuleNamespaceNames and TopLevelAwait entries
Fixesoxc-project/oxc#14258
<!-- START COPILOT CODING AGENT SUFFIX -->
<details>
<summary>Original prompt</summary>
>
> ----
>
> *This section details on the original issue you should resolve*
>
> <issue_title>transformer: warn top level await usage if not
supported</issue_title>
> <issue_description>A warning is emitted when BigInt is used and the
target does not support it
([playground](https://playground.oxc.rs/#eNptUj1vGzEM/SuGZg9Np9ZFp6YGAvQjyJCd0fEuSnTkgeQ5Dg7+76Euljwkk6RHkXzvkUuIYRcik9qmZ9783FzRj7ANHHZLkJnKkRNZ2PWQFbehZxnBDOUjcnPBTIC0BMLOZHYgKWcw7K4xZhCw5B3b75fHZKgTRGzQCDTkyzPyOAnqJUUjTx5+L66v4wPn+or9cP522oYJRAvXJeDRkNT7ul7To2uEnPnlDm0W+j+bpg73M8VCrZYqPVEOeAviuRVd8+6/3ZBJ8oqxBRSdtqX4W4TljDqH4t/Kwe/NmHdSBjKgmxtQv365+u6kZsVr7BPhnuVXBtV9wty1FnicUNKIZJDdS3YrWyuPjska+hcNOjBoPD6fwRLUdUyuBoXAXazWRe5wwHUDqIy4GfykHfvWnM0gYltrVSTjUP+uVerkivw6VlfO0x88YCv6jDj9gxHriNdUd5jz3t0uGQeUB9a6E0UPPWF085bL7eRwt9pX4HY7FbzYXDWd3gBEIxCc)).
Similar to that, it would be helpful if a warning is emitted for
top-level await as well.</issue_description>
>
> ## Comments on the Issue (you are @copilot in this section)
>
> <comments>
> </comments>
>
</details>
Fixesoxc-project/oxc#14258
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feat(transformer): add warning for arbitrary module namespace identifier
names
Implements warnings for the ES2020 "Arbitrary module namespace
identifier names" feature (TC39 proposal #2154), which allows string
literals as import/export specifiers. Similar to #14276.
### Changes
- **Compatibility data**: Added `ArbitraryModuleNamespaceNames` to
`tasks/compat_data/custom-compat-data.js` with browser support (Chrome
88+, Edge 88+, Opera 74+, Firefox 87+, Safari 14.1+, Node 16.0+, Deno
1.6+)
- **Transformer**: Added warning logic in `ES2020` for string literals
in `ImportSpecifier`, `ExportSpecifier`, and `ExportAllDeclaration`
nodes
- **Configuration**: Added `arbitrary_module_namespace_names` option and
environment target mapping
### Example
```javascript
// Triggers warning when targeting ES2019 or Chrome 87
export { foo as "kebab-case-name" };
import { "string-name" as bar } from "./module";
export * as "namespace" from "./module";
```
Warning message:
```
⚠ Arbitrary module namespace identifier names are not available in the configured target environment.
```
### Testing
Added integration tests covering supported/unsupported targets, multiple
literals, and normal identifiers.
<!-- START COPILOT CODING AGENT SUFFIX -->
<details>
<summary>Original prompt</summary>
> Similar to https://github.com/oxc-project/oxc/pull/14276, add a
warning for "Arbitrary module namespace identifier names" feature
(https://github.com/tc39/ecma262/pull/2154). Add the compat data to
`tasks/compat_data/custom-compat-data.js` as the data is not included in
the compat table.
</details>
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Boshen