The Form widget no longer supports being a sliver.

Previously, the Form widget essentially acted as a direct wrapper around its child. This design allowed a Form containing a sliver child (e.g., Form(child: other sliver)) to be treated as a sliver itself within a CustomScrollView or similar scrollable parent.

However, This PR introduced a new semantics widget within the Form widget's internal structure. This change alters its rendering behavior, meaning Form can no longer directly function as a sliver.

This change is part of an ongoing effort to improve the accessibility and semantic understanding of Flutter widgets. By embedding a semantics widget directly within Form, the framework can provide better information to accessibility services.

The core change is the integration of a semantics widget into the Form widget's build method.

If your app does not currently use the Form widget directly as a sliver within a scrollable list (e.g., as a direct child of CustomScrollView's slivers property), then no changes are required.

If your app use Form as a sliver, you will need to wrap the Form widget within a SliverToBoxAdapter. SliverToBoxAdapter is a sliver that contains a single box widget, converting a regular widget into a sliver that can be placed in a CustomScrollView.

Code before migration:

    sliver: Form(
        key: controller.formKey,
        child: SomeWidgetWithFormFields(),
    )

Code after migration:

    sliver: SliverToBoxAdapter(
        child: Form(
            key: controller.formKey,
            child: SomeWidgetWithFormFields(),
        )
    )

Landed in version: 3.35.0-pre In stable release: TBD

API documentation:

• Form

Relevant issues:

• Issue 161628

Relevant PRs:

• PR 170709: Add semantics role for form