Consider a library that uses a shared constant for host bindings. e.g.
```ts
export const BASE_BINDINGS= {
'[class.mat-themed]': '_isThemed',
}
----
@Directive({
host: {...BASE_BINDINGS, '(click)': '...'}
})
export class Dir1 {}
@Directive({
host: {...BASE_BINDINGS, '(click)': '...'}
})
export class Dir2 {}
```
Previously when these components were shipped as part of the
library to NPM, consumers were able to consume `Dir1` and `Dir2`.
No errors showed up.
Now with Ivy, when ngcc tries to process the library, an error
will be thrown. The error is stating that the host bindings should
be an object (which they obviously are). This happens because
TypeScript transforms the object spread to individual
`Object.assign` calls (for compatibility).
The partial evaluator used by the `@Directive` annotation handler
is unable to process this expression because there is no
integrated support for `Object.assign`. In View Engine, this was
not a problem because the `metadata.json` files from the library
were used to compute the host bindings.
Fixes#34659
PR Close#34661
ngcc has a basic integration test infrastructure that downlevels
TypeScript code into bundle formats that need to be processed by ngcc.
Until now, only ES5 bundles were created with a flat structure, however
more complex scenarios require an APF-like layout containing multiple
bundle formats.
PR Close#33875
In Angular View Engine, there are two kinds of decorator inheritance:
1) both the parent and child classes have decorators
This case is supported by InheritDefinitionFeature, which merges some fields
of the definitions (such as the inputs or queries).
2) only the parent class has a decorator
If the child class is missing a decorator, the compiler effectively behaves
as if the parent class' decorator is applied to the child class as well.
This is the "undecorated child" scenario, and this commit adds a migration
to ngcc to support this pattern in Ivy.
This migration has 2 phases. First, the NgModules of the application are
scanned for classes in 'declarations' which are missing decorators, but
whose base classes do have decorators. These classes are the undecorated
children. This scan is performed recursively, so even if a declared class
has a base class that itself inherits a decorator, this case is handled.
Next, a synthetic decorator (either @Component or @Directive) is created
on the child class. This decorator copies some critical information such
as 'selector' and 'exportAs', as well as supports any decorated fields
(@Input, etc). A flag is passed to the decorator compiler which causes a
special feature `CopyDefinitionFeature` to be included on the compiled
definition. This feature copies at runtime the remaining aspects of the
parent definition which `InheritDefinitionFeature` does not handle,
completing the "full" inheritance of the child class' decorator from its
parent class.
PR Close#33362
Paul Gschwendtner
JoostK
Alex Rickabaugh