Why&How tree-shaking this code after build?

[Yuliang-Lee]

Background

I have a front-end project that has a git submodule directory, and this submodule project is also referenced by other back-end projects, but the front-end only imports the enum variable. The packaged code contains typeorm schema code that was not imported in the front end

Reproduction

https://github.com/Yuliang-Lee/vite-treeshake-test

Problem code

builded code includes typeorm entity which project not imported?

[sapphi-red]

The easier way would be to separate the file and avoid importing the parts that is not needed in the front-end side.
For example, extract the enums in a separate file called src/git_submodule/typeorm/enums.ts and import that file from the front-end side and src/git_submodule/typeorm/test.ts.

The harder way would be to tell rollup the statements as side-effect free. In this case, import 'typeorm' and @Entity('t_test', { schema: 'db_a' }) call is assumed as side-effectful. For the former one, you can set build.rollupOptions.treeshake.moduleSideEffects: (id) => { if (id === 'typeorm') { return false } }. For the latter one, you can wrap it with IIFE and mark it with #__PURE__.

export const TTest = /* #__PURE__ */ (() => {
  @Index('t_id', ['id'], { unique: true })
  @Index('Finsert_time', ['finsertTime'], {})
  @Entity('t_test', { schema: 'db_a' })
  class r {
    @PrimaryGeneratedColumn({ type: 'int', name: 'id' })
    id: number
  
    @Column('varchar', { name: 'Fcreate_user', length: 255 })
    fcreateUser?: string
  
    @Column('int', { name: 'Fis', comment: '', default: () => "'0'" })
    fis: IS_ENUM
  
    @Column('datetime', { name: 'Finsert_time', default: () => "'1970-01-01 00:00:00'" })
    finsertTime?: Date
  
    @Column('datetime', { name: 'Fmodify_time', default: () => "'1970-01-01 00:00:00'" })
    fmodifyTime?: Date
  }
  return r
})()

[Yuliang-Lee]

thx for reply, I choose the "easier way" since the "harder way" seems would makes code more incomprehensible