bug(Datepicker): mat-datepicker-toggle does not announce expanded/collapsed state for screen readers

[RiinaKuu]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

mat-datepicker-toggle button uses aria-haspopup but does not inform screen reader users whether the popup is expanded or not.

Reproduction

Example link: https://material.angular.io/components/datepicker/examples

Steps to reproduce:

• Go to the Angular Material link above (I used Chrome)
• Start the screen reader (I used VoiceOver on MacOS)
• Navigate to the datepicker calendar button
• Realize that it is not informing you whether popup calendar is expanded or collapsed

Expected Behavior

The button should have aria-expanded attribute (which should always be paired if used aria-haspopup).

Actual Behavior

Environment

• Angular: 18.2.13
• CDK/Material: 18.2.14
• Browser(s): Chrome
• Operating System (e.g. Windows, macOS, Ubuntu): macOS

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}