fix(unplugin-vue-i18n): Support for transform.handler in vite:json plugin (#485)

Author: kazupon

packages/unplugin-vue-i18n/src/core/resource.ts

@@ -21,6 +21,8 @@ import {
   checkVuePlugin,
   error,
   getVitePlugin,
+  getVitePluginTransform,
+  overrideVitePluginTransform,
   raiseError,
   resolveNamespace,
   warn
@@ -136,11 +138,24 @@ export function resourcePlugin(
           `configResolved: isProduction = ${isProduction}, sourceMap = ${sourceMap}`
         )
 
+        /**
+         * NOTE:
+         * For the native rolldown plugin, we need to change to another solution from the current workaround.
+         * Currently, the rolldown team and vite team are discussing this issue.
+         * https://github.com/vitejs/rolldown-vite/issues/120
+         */
+
         // json transform handling
         const jsonPlugin = getVitePlugin(config, 'vite:json')
         if (jsonPlugin) {
-          const orgTransform = jsonPlugin.transform // backup @rollup/plugin-json
-          jsonPlugin.transform = async function (code: string, id: string) {
+          // saving `vite:json` plugin instance
+          const [orgTransform, transformWay] =
+            getVitePluginTransform(jsonPlugin)
+          if (!orgTransform) {
+            throw new Error('vite:json plugin not found!')
+          }
+
+          async function overrideViteJsonPlugin(code: string, id: string) {
             if (!/\.json$/.test(id) || filter(id)) {
               return
             }
@@ -162,6 +177,13 @@ export function resourcePlugin(
             // @ts-expect-error
             return orgTransform!.apply(this, [code, id])
           }
+
+          // override `vite:json` plugin transform function
+          overrideVitePluginTransform(
+            jsonPlugin,
+            overrideViteJsonPlugin,
+            transformWay!
+          )
         }
 
         /**

packages/unplugin-vue-i18n/src/utils/plugin.ts

@@ -19,6 +19,34 @@ export function getVitePlugin(
   return config.plugins.find(p => p.name === name) as RollupPlugin
 }
 
+export function getVitePluginTransform(
+  plugin: RollupPlugin
+): [RollupPlugin['transform'], 'handler' | 'transform' | undefined] {
+  if (plugin.transform) {
+    return 'handler' in plugin.transform
+      ? [plugin.transform.handler, 'handler']
+      : [plugin.transform, 'transform']
+  } else {
+    return [undefined, undefined]
+  }
+}
+
+// TODO: `override` type, we need more strict type
+export function overrideVitePluginTransform(
+  plugin: RollupPlugin,
+  override: Function,
+  to: 'handler' | 'transform'
+): void {
+  if (plugin.transform == undefined) {
+    throw new Error('plugin.transform is undefined')
+  }
+  if (to === 'handler' && 'handler' in plugin.transform) {
+    plugin.transform.handler = override as typeof plugin.transform.handler
+  } else {
+    plugin.transform = override as typeof plugin.transform
+  }
+}
+
 export function checkVuePlugin(vuePlugin: RollupPlugin | null): boolean {
   if (vuePlugin == null || !vuePlugin.api) {
     error(