Using a function imported from another file as a default value in withDefaults may prevent it from being tree-shaken

[wattanx]

Vue version

3.5.13

Link to minimal reproduction

https://stackblitz.com/edit/vitejs-vite-sr5itbdf

Steps to reproduce

1. npm install
2. npm run build
3. NotTreeShaken component exists in dist/assets/index-xxx.js

What is expected?

NotTreeShaken component is not imported, so it should be tree-shaken

What is actually happening?

NotTreeShaken component exists in dist/assets/index-xxx.js

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    vue: ^3.5.13 => 3.5.13

Any additional comments?

In the case of Props Destructure, it is tree-shaken.

In the case of withDefaults, props are compiled as follows:

props: {
  msg: { type: String, required: false, default: format('Hello World!!!   ') }
},

In the case of Props Destructure, it is compiled as follows:

props: {
  msg: { type: String, required: false, default: () => (format('Hello World!!!   ')) }
},

[wattanx]

Does this case correspond to the content of the following note?

Note that default values for mutable reference types (like arrays or objects) should be wrapped in functions when using withDefaults to avoid accidental modification and external side effects. This ensures each component instance gets its own copy of the default value. This is not necessary when using default values with destructure.

https://vuejs.org/api/sfc-script-setup.html#default-props-values-when-using-type-declaration

[edison1105]

Does this case correspond to the content of the following note?

Note that default values for mutable reference types (like arrays or objects) should be wrapped in functions when using withDefaults to avoid accidental modification and external side effects. This ensures each component instance gets its own copy of the default value. This is not necessary when using default values with destructure.

vuejs.org/api/sfc-script-setup.html#default-props-values-when-using-type-declaration

Yes, The meaning is roughly this: if a function is not used, the default value will be considered to have side effects and will not be tree-shaken. see rollupjs repl. you can try changing the default to a non-function and observe the outputted JS.