There have been breaking changes to the AST:
- `BlockStmtOrExpr` is now `ArrowFunctionBody`
- function bodies are `FunctionBody` instead of `BlockStmt`
- JSX text literals are `Wtf8Atom`, instead of `Atom`
### What?
Closes https://github.com/vercel/next.js/pull/92650
Closes https://github.com/vercel/next.js/issues/92547
When Turbopack runs SWC transform plugins, it passes a `TransformPluginMetadataContext` that includes the current `NODE_ENV`. Previously this value was hardcoded to `"development"` regardless of the actual build mode, causing SWC plugins to misbehave during production builds.
### Why?
`SwcPluginMetadataContext` is used by SWC plugins (e.g. `babel-plugin-styled-components`, `@swc/plugin-emotion`) to conditionally produce development vs. production output — for instance, injecting display names and data attributes only in development. With `NODE_ENV` always set to `"development"`, plugins could never produce their optimised production output, resulting in larger bundles and missing minification in `next build`.
Fixes https://github.com/vercel/next.js/issues/92547
### How?
`NODE_ENV` is now derived from the `process.env.NODE_ENV` compile-time define that is already part of `CompileTimeInfo` (the same source of truth used for dead-code elimination). The resolution happens in `EcmascriptModuleAsset::parse()` via a new shared helper `node_env_from_compile_time_info()` in `parse.rs`, and the value is stored on `TransformContext` so every `CustomTransformer` implementation can read it from `ctx.node_env` without needing access to the broader compilation context.
Key design decisions:
- **`TransformContext`** is the right place: it is the per-file context passed to every `CustomTransformer::transform()` call, so storing `node_env` there follows the existing pattern and avoids coupling the plugin struct to the build mode.
- **Webpack analysis path**: `compile_time_info` is now threaded through `webpack_runtime()`, `module_references()`, and the webpack reference structs (`WebpackModuleAsset`, `WebpackChunkAssetReference`, `WebpackEntryAssetReference`, `WebpackRuntimeAssetReference`) so that webpack-bundled files with SWC plugin transforms also receive the correct `NODE_ENV`.
- **`segment_config.rs`**: passes a placeholder but includes a comment explaining it is irrelevant since `EcmascriptInputTransforms::empty()` means no transforms run.
<!-- NEXT_JS_LLM_PR -->
Niklas Mischkulnig