Rspack 0.5 Release Announcement#

Major Feature Updates#

Module Federation added to Rspack#

Checkout this blog for more details.

Breaking Changes#

optimization.chunkIds is deterministic in production mode by default#

optimization.chunkIds is "deterministic" now in production mode, which aligns with webpack's default behavior.

Support rspack.HotModuleReplacementPlugin#

Support rspack.HotModuleReplacementPlugin in Rspack. If you are not using @rspack/dev-server and using a custom dev server, you need to apply HotModuleReplacementPlugin to enable HMR instead of setting devServer.hot to true, which is the same in webpack. This provides more compatibility with the plugin which uses HotModuleReplacementPlugin internally.

Remove default transformation#

Default transformation is a builtin, which internally transforms source files (such as TypeScript), into compatible sources (such as JavaScript). To make the transformation more customizable, we handed out this feature to users by using builtin:swc-loader and dropped the support of several rule.type. These rule.types are dropped:

• "typescript" or "ts"
• "tsx"
• "jsx"

In order to achieve old behavior, please remove rule.type or change it to "javascript/auto" and apply your custom loader configurations.

To transform a .jsx file:

module.exports = {
  module: {
    rules: [
      {
        test: /\.jsx$/,
        exclude: /[\\/]node_modules[\\/]/,
        loader: 'builtin:swc-loader',
        options: {
          sourceMap: true,
          jsc: {
            parser: {
              syntax: 'ecmascript',
              jsx: true,
            },
          },
        },
      },
    ],
  },
};

To transform a .tsx file:

module.exports = {
  module: {
    rules: [
      {
        test: /\.tsx$/,
        exclude: /[\\/]node_modules[\\/]/,
        loader: 'builtin:swc-loader',
        options: {
          sourceMap: true,
          jsc: {
            parser: {
              syntax: 'typescript',
              tsx: true,
            },
          },
        },
      },
    ],
  },
};

To transform a .ts file:

module.exports = {
  module: {
    rules: [
      {
        test: /\.ts$/,
        exclude: /[\\/]node_modules[\\/]/,
        loader: 'builtin:swc-loader',
        options: {
          sourceMap: true,
          jsc: {
            parser: {
              syntax: 'typescript',
            },
          },
        },
      },
    ],
  },
};

target does not affect user code anymore#

Rspack aligns target with webpack. Instead of transforming arbitrary user code, Rspack now lets loaders control the transformation of user land code. To transform user land code to which your target environment(s) needed, add env to builtin:swc-loader:

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /[\\/]node_modules[\\/]/,
        loader: "builtin:swc-loader",
        options: {
          jsc: {
            parser: {
              syntax: "ecmascript"
            }
          },
+         env: {
+           targets: "Chrome >= 48"
+         }
        }
      }
    ]
  }
}

Remove extended resolve extensions#

resolve.extensions helps us to omit certain file extensions during resolution. In previous versions, .ts, .tsx, .jsx are supported and these extensions are removed in the latest version, which aligns with webpack's behavior.

In order to get the same behavior, change resolve.extensions to this:

module.exports = {
  resolve: {
    extensions: ['...', '.tsx', '.ts', '.jsx'], // "..." means to extend from the default extensions
  },
};

Make @swc/helpers and react-refresh as peerDependencies#

Before we remove default transformation, it's possible to use it to degrade your code to es5 by target, and insert the react refresh helper code into your react component by builtin.react.refresh, so we installed the @swc/helpers and react-refresh as the dependencies of @rspack/core, to provide the out-of-box experience. But since we removed the default transformation now, and recommend using rsbuild for the out-of-box experience, the @swc/helpers and react-refresh no longer need to be installed by @rspack/core, and we make them as peerDependencies of @rspack/core.

If you are using externalHelpers: true with builtin:swc-loader or swc-loader, now you need to install @swc/helpers as dependencies of your project. If you are using @rspack/plugin-react-refresh, now you need to install react-refresh as devDependencies of your project.

Remove deprecated builtins options#

Some of the builtins options have been deprecated since v0.4.0.

If you are still using builtins.noEmitAssets, builtins.devFriendlySplitChunks, builtins.react, builtins.html, builtins.copy, builtins.minifyOptions, checkout migrating builtin options to builtin plugins to migrate.

And if you are still using builtins.presetEnv, builtins.decorator, builtins.pluginImport, builtins.emotion, builtins.relay, checkout the migration guide here.

Remove builtin:sass-loader#

builtin:sass-loader has been deprecated since v0.4.0. It's removed in v0.5.0. If you are still using it, migrate to sass-loader.

Remove experiments.incrementalRebuild options#

experiments.incrementalRebuild options has been deprecated since v0.4.0. It's removed in v0.5.0.

Remove builtins.devFriendlySplitChunks and experiments.newSplitChunks#

experiments.newSplitChunks and builtins.devFriendlySplitChunks has been deprecated since v0.4.0. It's removed in v0.5.0.

Remove experiments.rspackFuture.newResolver options#

experiments.rspackFuture.newResolver has been deprecated since v0.4.0. It's removed in v0.5.0.

Deprecating apply entry lazily#

Apply entry lazily is deprecating by rspackFuture: experiments.rspackFuture.disableApplyEntryLazily, which is introduced in v0.4.5, enabled by default in v0.5.0, and will be removed in v0.6.0.

When experiments.rspackFuture.disableApplyEntryLazily is false, options.entry can still make valid changes after rspack(options) is called, but with true it can't, and it's behave the same as webpack5.

This configuration has no effect on users developing applications in Rspack most of the time, but should be noted by developers of Rspack plugins or upper-level frameworks.

Migration Guide#

v0.5.0 removed lots of deprecated features, except that, v0.5.0 introduced four breaking changes, and you only need to notice two of them if you are developing applications using Rspack. So v0.5.0 is easy to migrate if you already migrate to v0.4+ with no deprecate warnings, if you haven't, checkout the v0.4.0 migration guide.

Add resolve.extensions#

This is a breaking change that is most likely to affect you.

After you upgrade @rspack/core to v0.5.0, if you build failed with error: Can't resolve './src/xxx.tsx', or Can't resolve './src/xxx.ts', or Can't resolve './src/xxx.jsx', you need to add resolve.extensions = ['...', '.tsx', '.ts', '.jsx'] in your configuration.

const configuration = {
  // ...
  resolve: {
+   extensions: ['...', '.tsx', '.ts', '.jsx'],
  },
}

You only need to add the needed extensions to resolve.extensions. For example, if you are not using any .tsx or .ts files, only using .js or .jsx files, then you only need to add '.jsx' to resolve.extensions. '.js' is one of the default extensions and all default extensions (['.js', '.json', '.wasm']) are represented by '...'.

Install @swc/helpers or react-refresh#

This is a breaking change that is most likely to affect you.

After you upgrade @rspack/core to v0.5.0, if you build failed with error: Failed to resolve @swc/helpers/xxx or Failed to resolve react-refresh/xxx, you need to install @swc/helpers or react-refresh in your project.

If you are using externalHelpers: true with builtin:swc-loader or swc-loader, now you need to install @swc/helpers as dependencies of your project.

npm install @swc/helpers

If you are using @rspack/plugin-react-refresh, now you need to install react-refresh as devDependencies of your project.

npm install react-refresh

Apply rspack.HotModuleReplacementPlugin#

If you are using @rspack/cli, or rsbuild, or other upper-level framework of Rspack to develop applications, you don't need to worry about this. This should be well handled by the upper-level framework or cli. But if you are using @rspack/core with a custom dev server (not @rspack/dev-server or webpack-dev-server), or developing a custom dev server, you need to notice this.

Before enabling HMR in Rspack is setting devServer.hot to true, but now you need to apply HotModuleReplacementPlugin by yourself in your custom dev server.

class CustomDevServer {
  // ...
  enableHMR(compiler) {
-   compiler.options.devServer ??= {};
-   compiler.options.devServer.hot = true;
+   new compiler.webpack.HotModuleReplacementPlugin().apply(compiler);
  }
}

Do not change entry options after rspack(options)#

If you are using @rspack/cli, or rsbuild, or other upper-level framework of Rspack to develop applications, you don't need to worry about this. This should be well handled by the upper-level framework or cli. But if you are developing a plugin or upper-level framework, you need to notice this.

Before prepending an extra entry in Rspack is prepending it to compiler.options.entry, but now you need to apply EntryPlugin by yourself.

const rspack = require('@rspack/core');
const compiler = rspack(options);

function prependEntry(compiler, additionalEntry) {
-  for (const key in compiler.options.entry) {
-    compiler.options.entry[key].import = [
-      additionalEntry,
-      ...(compiler.options.entry[key].import || []),
-    ];
-  }
+  new compiler.webpack.EntryPlugin(compiler.context, additionalEntry, {
+    name: undefined, // `name: undefined` to prepend the it to every entry, or add it to a specified entry with specified entry name
+  }).apply(compiler);
}

prependEntry(compiler, 'dev-client.js');