Prepares the `@angular-devkit/schematics` package for the eventual change of enabling the
TypeScript `useUnknownInCatchVariables` option. This option provides additional
code safety by ensuring that the catch clause variable is the proper type before
attempting to access its properties. Similar changes will be needed in the other
packages in the repository prior to enabling `useUnknownInCatchVariables`.
The `_resolveReferenceString` abstract method of the `FileSystemEngineHostBase` class now has a third parameter
that provides the collection description of the schematic currently being resolved. This allows the resolver to
use any fields/options present within the collection description to adjust the resolution of the schematic. The
`encapsulation` optional field is also added to the `FileSystemCollectionDescription` type which will in the future
allow control of the `@angular/cli` VM context wrapping on an individual schematic collection basis.
This change first attempts to resolve a schematic referenced via the external schematic rule from the requesting schematic collection. This allows schematic packages that are direct dependencies of another schematic package to be used with the external schematic rule without manual package resolution code within the schematic.
Closes#18098Closes#11026
With Angular CLI version 8, migrations cannot be re-run with the
`--migrate-only` flag as there was a recent regression introduced
in e406f00909 (diff-0d0a748fb9a38a7ccde08d9b42e70bce) as it now passes
a normalized platform path to the `engine.createCollection` call.
This breaks as there is incorrect logic within
`node-modules-engine-host` that causes the schematic collection to be
searched within the `package.json#schematics` entry. This is incorrect
as migration schematics specify their migration schematics in a separate
schematic collection file which is part of `package.json#ng-update`.
Fixes#14565
