Display warning on reexporting in shared public API large size module that affects bundle size

[ratomiru]

Problem

According to "Large bundles and broken tree-shaking in Shared", there may be some cases where one shared module size is extremely large. In these cases using something like button on page 1 can lead to downloading whole big heavy package like drag'n'drop library which is intended for page 2

Solution

It would be nice to check total external packages size a reexported file uses. I am not sure, is it possible technically, so I just share the idea

Some points

• Using the same way as Import Cost VSCode Extension for calculating packages sizes of some module (AST based approach)

Example

/shared/ui
    button.tsx // chakra-ui: 54k, total: 54k
    date-picker.tsx // chakra-ui: 54k, dayjs: 8k, total: 62k
    code-editor // @codeium/react-code-editor: 4mb, total: 4mb

shared/ui/index.ts

export { Button } from './button'
export { DatePicker } from './date-picker'
export { CodeEditor } from './code-editor' // 4mb is quite heavy so linter will show warning

[illright]

That's an interesting idea, thanks! Would be interesting to explore this from the performance perspective. Another question is how relevant this diagnostic is for modern bundlers like Vite or esbuild. We should do some testing here to identify if this rule would actually help people avoid excessively large bundles due to FSD's public API rules.