invalid_deprecated_extend_annotation
The annotation '@Deprecated.extend' can only be applied to extendable classes.
Description
#
The analyzer produces this diagnostic when the @Deprecated.extend
annotation is applied to a declaration that isn't an extendable class. An
extendable class is one that isn't declared with the interface,
final, or sealed keywords and has at least one public, generative
constructor.
Example
#The following code produces this diagnostic because the annotation is on a sealed class:
dart
@Deprecated.extend()
sealed class C {}
Common fixes
#Remove the annotation:
dart
sealed class C {}