bug(mat-form-field): When matTextPrefix is applied, float-above transform applied to label element instead of class

[bmayen]

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

Not sure if this is a regression or not

Description

The floating label transform is normally applied via the label .mdc-floating-label--float-above class. However, when matTextPrefix is used on the mat-form-field, the transform is instead applied to the label element itself via inline style attribute. This makes attaching custom styles to the floated label inconsistent since the inline style has higher specificity than .mdc-floating-label--float-above class.

Reproduction

Apply matTextPrefix to an outline mat-form-field with a mat-label. Observe how transform styling is applied inline to the label.

https://components-issue-da4zuo.stackblitz.io/

Expected Behavior

I would expect transform styling to be applied consistently via .mdc-floating-label--float-above class.

Actual Behavior

Transform styling is applied via .mdc-floating-label--float-above class when matTextPrefix is not present, but applied via inline styling on the label element when matTextPrefix is present.

Environment

• Angular: 16.x
• CDK/Material: 16.x
• Browser(s): Chrome
• Operating System (e.g. Windows, macOS, Ubuntu): macOS

[zarend]

Hello @bmayen ,

Do you have a Stackblitz reproduction of this issue?

This makes attaching custom styles to the floated label inconsistent

We generally recommend developers uses tokens and theming to apply custom styles.

Best Regards,

Zach

[bmayen]

Hi @zarend I added Stackblitz repro above. You can see there how the first two form fields apply the transform via class, while the third applies it via inline style directly on the label element.