Passing a seemingly empty type to defineProps with defineDefaults throws an error

[simonwep]

Describe the bug

If the type passed to defineProps in combination with defineDefaults is seemingly empty (either actually empty or the interface used for props extends another but doesn't add any additional types) and the value is stored in a variable an error is thrown.

Reproduction

Considering the following, empty component:

<template></template>

<script setup lang="ts">
interface BaseProps {
    msg: string;
}

interface Props extends BaseProps {}

const props = withDefaults(defineProps<Props>(), {});
</script>

where Props can also be

interface Props {}

or

type Props = {};

or not used at all:

<template>

</template>

<script setup lang="ts">
const props = withDefaults(defineProps<{}>(), {});
</script>

throws an error:

10:25:01 AM [vite] Internal server error: Transform failed with 1 error:
xxx/src/components/HelloWorld.vue:7:26: error: Unexpected "}"
  Plugin: vite:vue
  File: xxx/src/components/HelloWorld.vue
  
  Unexpected "}"
  5  |    expose()
  6  |  
  7  |  const props = __props as  }
     |                            ^
  8  |  
  9  |  
  
      at failureErrorWithLog (xxx/node_modules/esbuild/lib/main.js:1493:15)
      at xxx/node_modules/esbuild/lib/main.js:1282:29
      at xxx/node_modules/esbuild/lib/main.js:629:9
      at handleIncomingPacket (xxx/node_modules/esbuild/lib/main.js:726:9)
      at Socket.readFromStdout (xxx/node_modules/esbuild/lib/main.js:596:7)
      at Socket.emit (node:events:390:28)
      at addChunk (node:internal/streams/readable:315:12)
      at readableAddChunk (node:internal/streams/readable:289:9)
      at Socket.Readable.push (node:internal/streams/readable:228:10)
      at Pipe.onStreamRead (node:internal/stream_base_commons:199:23)

System Info

System:
    OS: Linux 5.13 Ubuntu 21.10 21.10 (Impish Indri)
    CPU: (16) x64 AMD Ryzen 7 5800H with Radeon Graphics
    Memory: 7.67 GB / 31.22 GB
    Container: Yes
    Shell: 5.1.8 - /bin/bash
  Binaries:
    Node: 16.11.0 - /usr/local/bin/node
    npm: 8.1.1 - /usr/local/bin/npm
  Browsers:
    Chrome: 95.0.4638.54
  npmPackages:
    @vitejs/plugin-vue: ^1.9.4 => 1.9.4 
    vite: ^2.6.12 => 2.6.12

Used Package Manager

npm

Logs

vite:config bundled config file loaded in 638.70ms +0ms
  vite:config using resolved config: {
  vite:config   plugins: [
  vite:config     'alias',
  vite:config     'vite:modulepreload-polyfill',
  vite:config     'vite:resolve',
  vite:config     'vite:html-inline-script-proxy',
  vite:config     'vite:css',
  vite:config     'vite:esbuild',
  vite:config     'vite:json',
  vite:config     'vite:wasm',
  vite:config     'vite:worker',
  vite:config     'vite:asset',
  vite:config     'vite:vue',
  vite:config     'vite:define',
  vite:config     'vite:css-post',
  vite:config     'vite:build-html',
  vite:config     'commonjs',
  vite:config     'vite:data-uri',
  vite:config     'rollup-plugin-dynamic-import-variables',
  vite:config     'vite:asset-import-meta-url',
  vite:config     'vite:build-import-analysis',
  vite:config     'vite:esbuild-transpile',
  vite:config     'vite:reporter',
  vite:config     'vite:load-fallback'
  vite:config   ],
  vite:config   build: {
  vite:config     target: [ 'es2019', 'edge88', 'firefox78', 'chrome87', 'safari13.1' ],
  vite:config     polyfillModulePreload: true,
  vite:config     outDir: 'dist',
  vite:config     assetsDir: 'assets',
  vite:config     assetsInlineLimit: 4096,
  vite:config     cssCodeSplit: true,
  vite:config     cssTarget: [ 'es2019', 'edge88', 'firefox78', 'chrome87', 'safari13.1' ],
  vite:config     sourcemap: false,
  vite:config     rollupOptions: {},
  vite:config     minify: 'esbuild',
  vite:config     terserOptions: {},
  vite:config     write: true,
  vite:config     emptyOutDir: null,
  vite:config     manifest: false,
  vite:config     lib: false,
  vite:config     ssr: false,
  vite:config     ssrManifest: false,
  vite:config     reportCompressedSize: true,
  vite:config     chunkSizeWarningLimit: 500,
  vite:config     watch: null,
  vite:config     commonjsOptions: { include: [Array], extensions: [Array] },
  vite:config     dynamicImportVarsOptions: { warnOnError: true, exclude: [Array] }
  vite:config   },
  vite:config   define: { __VUE_OPTIONS_API__: true, __VUE_PROD_DEVTOOLS__: false },
  vite:config   ssr: { external: [ 'vue', '@vue/server-renderer' ] },
  vite:config   configFile: 'xxx/vite.config.ts',
  vite:config   configFileDependencies: [ 'vite.config.ts' ],
  vite:config   inlineConfig: {
  vite:config     root: undefined,
  vite:config     base: undefined,
  vite:config     mode: undefined,
  vite:config     configFile: undefined,
  vite:config     logLevel: undefined,
  vite:config     clearScreen: undefined,
  vite:config     build: {}
  vite:config   },
  vite:config   root: 'xxx',
  vite:config   base: '/',
  vite:config   resolve: { dedupe: undefined, alias: [ [Object], [Object] ] },
  vite:config   publicDir: 'xxx/public',
  vite:config   cacheDir: 'xxx/node_modules/.vite',
  vite:config   command: 'build',
  vite:config   mode: 'production',
  vite:config   isProduction: true,
  vite:config   server: { fs: { strict: undefined, allow: [Array] } },
  vite:config   env: { BASE_URL: '/', MODE: 'production', DEV: false, PROD: true },
  vite:config   assetsInclude: [Function: assetsInclude],
  vite:config   logger: {
  vite:config     hasWarned: false,
  vite:config     info: [Function: info],
  vite:config     warn: [Function: warn],
  vite:config     warnOnce: [Function: warnOnce],
  vite:config     error: [Function: error],
  vite:config     clearScreen: [Function: clearScreen],
  vite:config     hasErrorLogged: [Function: hasErrorLogged]
  vite:config   },
  vite:config   createResolver: [Function: createResolver],
  vite:config   optimizeDeps: {
  vite:config     esbuildOptions: { keepNames: undefined, preserveSymlinks: undefined }
  vite:config   }
  vite:config } +6ms
vite v2.6.12 building for production...
transforming (6) src/App.vue  vite:esbuild esbuild error with options used:  {
  sourcemap: false,
  sourcefile: 'xxx/src/components/HelloWorld.vue',
  loader: 'ts',
  tsconfigRaw: { compilerOptions: { useDefineForClassFields: true } }
} +0ms
✓ 9 modules transformed.
[vite:vue] Transform failed with 1 error:
xxx/src/components/HelloWorld.vue:7:26: error: Unexpected "}"
file: xxx/src/components/HelloWorld.vue:7:26

Unexpected "}"
5  |    setup(__props: any) {
6  |  
7  |  const props = __props as  }
   |                            ^
8  |  
9  |  

error during build:
Error: Transform failed with 1 error:
xxx/src/components/HelloWorld.vue:7:26: error: Unexpected "}"
    at failureErrorWithLog (xxx/node_modules/esbuild/lib/main.js:1493:15)
    at xxx/node_modules/esbuild/lib/main.js:1282:29
    at xxx/node_modules/esbuild/lib/main.js:629:9
    at handleIncomingPacket (xxx/node_modules/esbuild/lib/main.js:726:9)
    at Socket.readFromStdout (xxx/node_modules/esbuild/lib/main.js:596:7)
    at Socket.emit (node:events:390:28)
    at addChunk (node:internal/streams/readable:315:12)
    at readableAddChunk (node:internal/streams/readable:289:9)
    at Socket.Readable.push (node:internal/streams/readable:228:10)
    at Pipe.onStreamRead (node:internal/stream_base_commons:199:23)

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/vue-next instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[bluwy]

I can still reproduce this with plugin-vue 2.2.4. Here's a stackblitz repro: https://stackblitz.com/edit/vitejs-vite-crwqk9?file=src%2Fcomponents%2FHelloWorld.vue&terminal=dev

[sapphi-red]

@bluwy I found this is a duplicate of #7343 which is reported to vuejs/core by vuejs/core#5613.

[bluwy]

Ah thanks @sapphi-red. Let's move the discussion over there then.