[Select] does not accept slotProp: **placement**

[Erpix3lt]

Steps to reproduce

Link to live example: https://stackblitz.com/edit/react-fpjpbc?file=Demo.tsx

import * as React from 'react';
import {
  Select as BaseSelect,
  SelectProps,
  selectClasses,
  SelectRootSlotProps,
} from '@mui/base/Select';
import { Option as BaseOption, optionClasses } from '@mui/base/Option';
import { styled } from '@mui/system';
import UnfoldMoreRoundedIcon from '@mui/icons-material/UnfoldMoreRounded';

/* … */

Steps:

1. Run the demo

Current behavior

After passing slotProps={{ popup: { placement: 'top' } }} to the select component, the placement of the popup cannot be modified.

Expected behavior

One should expect the popup to spawn in the given direction.

Context

As I do have another bug with the implementation of my modified select component, where I cannot retrieve the placement of the popup using the const popupContext = useContext(PopupContext); I do want to limit the opening behaviour to only open towards the bottom, in order to always apply correct styling.

Your environment

npx @mui/envinfo

  System:
    OS: macOS 14.6.1
  Binaries:
    Node: 21.6.1 - ~/.nvm/versions/node/v21.6.1/bin/node
    npm: 10.2.4 - ~/.nvm/versions/node/v21.6.1/bin/npm
    pnpm: Not Found
  Browsers:
    Chrome: 127.0.6533.120
    Edge: Not Found
    Safari: 17.6
  npmPackages:
    @emotion/react: ^11.11.1 => 11.11.4
    @emotion/styled: ^11.11.0 => 11.11.5
    @mui/base: 5.0.0-beta.40 => 5.0.0-beta.40
    @mui/core-downloads-tracker:  5.16.7
    @mui/icons-material: 5.16.6 => 5.16.6
    @mui/material: 5.16.6 => 5.16.6
    @mui/private-theming:  5.16.6
    @mui/styled-engine:  5.16.6
    @mui/styles: 5.16.6 => 5.16.6
    @mui/system: 5.16.6 => 5.16.6
    @mui/types:  7.2.15
    @mui/utils: 5.16.6 => 5.16.6
    @types/react: ^18.2.20 => 18.3.3
    react: ^18.2.0 => 18.3.1
    react-dom: ^18.2.0 => 18.3.1
    typescript: ^5.0.0 => 5.5.3

Search keywords: Select, Popup

[michaldudak]

We're currently overhauling the Select component (#541). The revised implementation will be more customizable.

[Erpix3lt]

@michaldudak When can we expect the new implementation?

[michaldudak]

The PR will be merged when it's done. We release alphas roughly every six weeks, but we don't guarantee that the API will be stable.
We tentatively plan to release the stable version of Base UI early next year.