prefer-explicit-function-type

added in: 1.11.0

warning

Pro+

preset: recommended

Warns when a Function type does not specify the return type and arguments.

Not specifying the return type and the list of arguments can lead to hard-to-spot bugs since the Function type effectively makes the declaration dynamic and disables type checks.

Example

❌ Bad:

class SomeWidget {
  final Function onTap; // LINT: This 'Function' type does not specify a return type or parameter list. Try adding them.

  const SomeWidget(this.onTap);
}

✅ Good:

class SomeWidget {
  final void Function() onTap;

  const SomeWidget(this.onTap);
}