Previously the injectable compiler assumed all tree-shakeable injectables
would have dependencies that were injectables or InjectionTokens. However
old code still uses string tokens (e.g. NgUpgrade and '$injector'). Using
such tokens would cause the injectable compiler to crash.
Now, the injectable compiler can properly generate a dependency on such a
string token.
PR Close#22376
InjectionToken can be created with an ngInjectableDef, and previously
this allowed the full expressiveness of @Injectable. However, this
requires a runtime reflection system in order to generate factories
from expressed provider declarations.
Instead, this change requires scoped InjectionTokens to provide the
factory directly (likely using inject() for the arguments), bypassing
the need for a reflection system.
Fixes#22205
PR Close#22207
This commit bundles 3 important changes, with the goal of enabling tree-shaking
of services which are never injected. Ordinarily, this tree-shaking is prevented
by the existence of a hard dependency on the service by the module in which it
is declared.
Firstly, @Injectable() is modified to accept a 'scope' parameter, which points
to an @NgModule(). This reverses the dependency edge, permitting the module to
not depend on the service which it "provides".
Secondly, the runtime is modified to understand the new relationship created
above. When a module receives a request to inject a token, and cannot find that
token in its list of providers, it will then look at the token for a special
ngInjectableDef field which indicates which module the token is scoped to. If
that module happens to be in the injector, it will behave as if the token
itself was in the injector to begin with.
Thirdly, the compiler is modified to read the @Injectable() metadata and to
generate the special ngInjectableDef field as part of TS compilation, using the
PartialModules system.
Additionally, this commit adds several unit and integration tests of various
flavors to test this change.
PR Close#22005
Alex Rickabaugh