Paul Gschwendtner 32eafef6a7 fix(core): undecorated-classes-with-decorated-fields migration does not decorate derived classes (#35339)
The `undecorated-classes-with-decorated-fields` migration has been
introduced with 904a2018e0d3394ad91ffb6472f8271af7845295, but misses
logic for decorating derived classes of undecorated classes which use
Angular features. Example scenario:

```ts
export abstract class MyBaseClass {
  @Input() someInput = true;
}

export abstract class BaseClassTwo extends MyBaseClass {}

@Component(...)
export class MyButton extends BaseClassTwo {}
```

Both abstract classes would need to be migrated. Previously, the migration
only added `@Directive()` to `MyBaseClass`, but with this change, it
also decorates `BaseClassTwo`.

This is necessary because the Angular Compiler requires `BaseClassTwo` to
have a directive definition when it flattens the directive metadata for
`MyButton` in order to perform type checking. Technically, not decorating
`BaseClassTwo` does not break at runtime.

We basically want to enforce consistent use of `@Directive` to simplify the
mental model. [See the migration guide](https://angular.io/guide/migration-undecorated-classes#migrating-classes-that-use-field-decorators).

Fixes #34376.

PR Close #35339
2020-04-02 10:51:48 -07:00
..