| name | rspack-webpack-gap-tracker |
| description | Use when tracking, auditing, or updating Rspack compatibility gaps against webpack, including missing webpack features, built-in and ecosystem plugin compatibility gaps, completed compatibility features, and missing webpack test coverage. |
Rspack Webpack Gap Tracker
Tracking Targets
Required Output Shape
Keep the issue and comments as lists, not prose-only summaries.
- Main issue body: missing Rspack features compared with webpack, grouped by implementation recommendation.
- Completed feature comment: webpack compatibility features that Rspack has completed.
- Missing test comment: webpack tests missing from Rspack that are not already covered by a missing feature or PR-specific feature gap.
Every update to the issue body or either placeholder comment must include a visible update time, using the local timezone when possible:
Last updated: YYYY-MM-DD HH:mm:ss Z
Audit Workflow
- Read the current tracking issue and its comments before adding anything.
- Preserve the existing issue and comment format when updating; only change the relevant timestamp and list entries.
- Check associated, linked, or subtask issues for each candidate gap. If a related issue or subtask already records the same content, do not duplicate it in the main tracking issue.
- Compare new findings with both missing and completed lists to avoid duplicates.
- Search for missing functionality from these directions:
- New webpack release features since the last recorded update.
- Differences between webpack's config object and Rspack's config object.
- Differences between Rspack built-in plugins and webpack built-in plugins, plus commonly-used webpack ecosystem plugins that Rspack provides built-in alternatives for.
- Rspack PRs merged since the last recorded update, especially large changes and PRs labeled or titled as features.
- Existing issue entries and completed entries, to avoid re-recording already tracked work.
- Classify each missing feature into one of these recommendation buckets:
- Recommended to implement in Rspack: gaps in config or plugin functionality that Rspack already exposes, or features that need native Rust/compiler integration for correctness or performance.
- Pending evaluation: gaps where the right home is unclear, or where webpack support may be experimental, low priority, or partially covered by existing Rspack/Rsbuild behavior.
- Not recommended to implement in Rspack: plugin or integration features that can be implemented outside Rspack without native Rust work or performance impact; prefer a third-party package or an independent plugin under https://github.com/rstackjs when the compatibility layer should be maintained by the Rstack ecosystem.
- Before marking a feature as not recommended or pending, inspect the corresponding webpack feature or plugin implementation. Check whether Rsbuild already provides a solution, and whether https://github.com/rstackjs already has a compatible package or plugin.
- If the gap is native CSS-related, record it in #14002 instead of #14556.
- For missing tests:
- If a missing webpack test maps clearly to a tracked feature gap or a specific PR gap, mention it under that feature instead of adding it to the standalone missing-test comment.
- Otherwise, list missing tests by webpack test directory.
- Include older missing tests directly; do not hide them just because they predate the last update.
Suggested Investigation Sources
- Webpack releases and changelog for new feature candidates.
- Webpack config schema/types and Rspack config schema/types for option-level gaps.
- Webpack built-in plugin docs/source, Rspack built-in plugin exports/source, and webpack ecosystem plugin docs/source for plugin-compatibility gaps.
- Webpack feature/plugin implementation details when deciding whether the gap belongs in Rspack, an external package, or an Rstack ecosystem plugin.
- GitHub merged PRs in
web-infra-dev/rspack since the last update.
- Existing Rspack issues, linked issues, subtask issues, and the completed-feature comment for deduplication.
- Rsbuild docs/source and https://github.com/rstackjs packages for existing compatibility solutions.
tests/rspack-test/ and the local webpack checkout, when available, for test coverage comparison.
Entry Format
Use concise checklist entries. Prefer one feature or test group per item.
Missing feature entry:
- [ ] `<feature or option>` - Short compatibility note. Recommendation: recommended/pending/not recommended, with a short reason. Source: webpack release/config/PR link.
Completed feature entry:
- [x] `<feature or option>` - Completed in Rspack via PR/commit/issue link.
Missing test entry:
- [ ] `<webpack test directory>` - Missing notable cases: `case-a`, `case-b`. Related feature: none.
If a source is uncertain, mark it as needing verification instead of presenting it as confirmed.
