[system] Fix inconsistent multiple types for mergeBreakpointsInOrder

[dylnic]

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Steps to reproduce 🕹

Link to live example: https://codesandbox.io/s/mui-mergebreakpointsinorder-type-83gd2y

Steps:

1. import { mergeBreakpointsInOrder } from "@mui/system";
2. pass in a theme object created with createTheme();
3. observe TypeScript error

Current behavior 😯

The typing for the mergeBreakpointsInOrder changes depending on where you import it from. If you import from the barrel file it appears to use an old type incompatible with the current theme breakpoints. However the function is typed correctly if you use a path import.

This works:
import { mergeBreakpointsInOrder } from "@mui/system/breakpoints";

This doesn't:
import { mergeBreakpointsInOrder } from "@mui/system";

Expected behavior 🤔

The same type should be used regardless of how you import the function.

Context 🔦

No response

Your environment 🌎

npx @mui/envinfo

  Don't forget to mention which browser you used.
  Output from `npx @mui/envinfo` goes here.

[dylnic]

Hi @mnajdova, I'm happy to raise a PR for this, let me know :)

[ZeeshanTamboli]

@dylnic Thank you for bringing up this issue. You're absolutely right – the type definition should remain consistent, no matter where it's imported from. Please feel free to create a pull request to fix this. Additionally, would you be willing to share your specific use case for using this method?

[imevanc]

@dylnic Thank you for bringing up this issue. You're absolutely right – the type definition should remain consistent, no matter where it's imported from. Please feel free to create a pull request to fix this. Additionally, would you be willing to share your specific use case for using this method?

@ZeeshanTamboli - Can you assign this to me?

[dylnic]

@ZeeshanTamboli no worries :) We're leveraging mui in a component library and need to add responsive props to some of the custom components that don't use mui under the hood.

[imevanc]

@ZeeshanTamboli - Can you please add the system label or similar, so it doesn't break the pipeline? Cheers!