fix(dev): trigger prune event when last import is removed (#20781)

packages/vite/src/node/plugins/importAnalysis.ts

@@ -296,7 +296,17 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
         !imports.length &&
         !(this as unknown as TransformPluginContext)._addedImports
       ) {
-        importerModule.isSelfAccepting = false
+        const prunedImports = await moduleGraph.updateModuleInfo(
+          importerModule,
+          new Set(),
+          null,
+          new Set(),
+          null,
+          false,
+        )
+        if (prunedImports) {
+          handlePrunedModules(prunedImports, environment)
+        }
         debug?.(
           `${timeFrom(msAtStart)} ${colors.dim(
             `[no imports] ${prettifyUrl(importer, root)}`,

playground/hmr/prune/dep1.js

@@ -1,8 +1 @@
 import './dep2.js'
-
-// TODO: https://github.com/vitejs/vite/issues/20781
-// currently we need one more `import` in this module
-// to trigger prune for depending module `dep2.js` since
-// the prune event logic is skipped when `es-module-lexer`
-// detects `imports.length === 0`
-import './dep2-other.js'