deprecated_factory_method

Methods named 'factory' will become constructors when the primary_constructors feature is enabled.

The analyzer produces this diagnostic when the declaration of an instance method named factory is interpreted as a constructor declaration after the primary_constructors feature is enabled.

This issue only affects declarations that lack a return type and where the method name is the first token or is preceded only by external, augment, or augment external. The augment and augment external keywords are valid only after the augmentations feature is enabled.

The following code produces this diagnostic because the instance method named factory has no return type or modifiers:

// @dart=3.10
class C {
  factory() => C();
}

If the name can be changed, then rename the method:

// @dart=3.10
class C {
  make() => C();
}

If the name must remain factory, then add a return type:

// @dart=3.10
class C {
  C factory() => C();
}