[code-infra] Avoid loading barrel file during type checking

[Janpot]

Noticed during type checking of the following:

import * as React from 'react';
import Button from '@mui/material/Button';

export default function Test() {
  return <Button>hello</Button>;
}

That it loaded the whole type declarations for @mui/material top-level barrel file:

I saw there were lots of imports from '..' in the individual subpaths. This is wasteful, better to import more deeply.

-import { Theme } from '..';
+import { Theme } from '../styles';

after:

You can see there's still a large chunk being loaded for them, it still imports all component props for the theme. But it's already about 30% faster (according to those two traces, I didn't sample multiple runs).

• Will look into whether this theme declaration file can be further optimized.
• Will also investigate in follow-up whether we can enforce this with eslint.

[mui-bot]

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[JCQuintas]

I suppose these imports can be caused by some IDE configs, would there be an eslint rule so we can block these? 🤔

[Janpot]

I moved the internal type to @mui/material/internal

I suppose these imports can be caused by some IDE configs, would there be an eslint rule so we can block these? 🤔

Quite hard to do with eslint-plugin-imports, but I'm adding a custom plugin in a separate PR

[sai6855]

test-types CI check is failing after merging latest master in this PR #45975, looks like this PR might be causing the issue although not entirely sure. https://circleci.com/gh/mui/material-ui/827381

Edit: Issue might be in PR itself

[Janpot]

Edit: Issue might be in PR itself

👍 Ok, let me know.

[DiegoAndai]

Thanks @Janpot