Removes `ViewEncapsulation.Native` which has been deprecated for several major versions.
BREAKING CHANGES:
* `ViewEncapsulation.Native` has been removed. Use `ViewEncapsulation.ShadowDom` instead. Existing
usages will be updated automatically by `ng update`.
PR Close#38882
Updates to rules_nodejs 2.2.0. This is the first major release in 7 months and includes a number of features as well
as breaking changes.
Release notes: https://github.com/bazelbuild/rules_nodejs/releases/tag/2.0.0
Features of note for angular/angular:
* stdout/stderr/exit code capture; this could be potentially be useful
* TypeScript (ts_project); a simpler tsc rule that ts_library that can be used in the repo where ts_library is too
heavy weight
Breaking changes of note for angular/angular:
* loading custom rules from npm packages: `ts_library` is no longer loaded from `@npm_bazel_typescript//:index.bzl`
(which no longer exists) but is now loaded from `@npm//@bazel/typescript:index.bzl`
* with the loading changes above, `load("@npm//:install_bazel_dependencies.bzl", "install_bazel_dependencies")` is
no longer needed in the WORKSPACE which also means that yarn_install does not need to run unless building/testing
a target that depends on @npm. In angular/angular this is a minor improvement as almost everything depends on @npm.
* @angular/bazel package is also updated in this PR to support the new load location; Angular + Bazel users that
require it for ng_package (ng_module is no longer needed in OSS with Angular 10) will need to load from
`@npm//@angular/bazel:index.bzl`. I investigated if it was possible to maintain backward compatability for the old
load location `@npm_angular_bazel` but it is not since the package itself needs to be updated to load from
`@npm//@bazel/typescript:index.bzl` instead of `@npm_bazel_typescript//:index.bzl` as it depends on ts_library
internals for ng_module.
* runfiles.resolve will now throw instead of returning undefined to match behavior of node require
Other changes in angular/angular:
* integration/bazel has been updated to use both ng_module and ts_libary with use_angular_plugin=true.
The latter is the recommended way for rules_nodejs users to compile Angular 10 with Ivy. Bazel + Angular ViewEngine is
supported with @angular/bazel <= 9.0.5 and Angular <= 8. There is still Angular ViewEngine example on rules_nodejs
https://github.com/bazelbuild/rules_nodejs/tree/stable/examples/angular_view_engine on these older versions but users
that want to update to Angular 10 and are on Bazel must switch to Ivy and at that point ts_library with
use_angular_plugin=true is more performant that ng_module. Angular example in rules_nodejs is configured this way
as well: https://github.com/bazelbuild/rules_nodejs/tree/stable/examples/angular. As an aside, we also have an
example of building Angular 10 with architect() rule directly instead of using ts_library with angular plugin:
https://github.com/bazelbuild/rules_nodejs/tree/stable/examples/angular_bazel_architect.
NB: ng_module is still required for angular/angular repository as it still builds ViewEngine & @angular/bazel
also provides the ng_package rule. ng_module can be removed in the future if ViewEngine is no longer needed in
angular repo.
* JSModuleInfo provider added to ng_module. this is for forward compat for future rules_nodejs versions.
PR Close#39182
Updates to rules_nodejs 2.2.0. This is the first major release in 7 months and includes a number of features as well
as breaking changes.
Release notes: https://github.com/bazelbuild/rules_nodejs/releases/tag/2.0.0
Features of note for angular/angular:
* stdout/stderr/exit code capture; this could be potentially be useful
* TypeScript (ts_project); a simpler tsc rule that ts_library that can be used in the repo where ts_library is too
heavy weight
Breaking changes of note for angular/angular:
* loading custom rules from npm packages: `ts_library` is no longer loaded from `@npm_bazel_typescript//:index.bzl`
(which no longer exists) but is now loaded from `@npm//@bazel/typescript:index.bzl`
* with the loading changes above, `load("@npm//:install_bazel_dependencies.bzl", "install_bazel_dependencies")` is
no longer needed in the WORKSPACE which also means that yarn_install does not need to run unless building/testing
a target that depends on @npm. In angular/angular this is a minor improvement as almost everything depends on @npm.
* @angular/bazel package is also updated in this PR to support the new load location; Angular + Bazel users that
require it for ng_package (ng_module is no longer needed in OSS with Angular 10) will need to load from
`@npm//@angular/bazel:index.bzl`. I investigated if it was possible to maintain backward compatability for the old
load location `@npm_angular_bazel` but it is not since the package itself needs to be updated to load from
`@npm//@bazel/typescript:index.bzl` instead of `@npm_bazel_typescript//:index.bzl` as it depends on ts_library
internals for ng_module.
* runfiles.resolve will now throw instead of returning undefined to match behavior of node require
Other changes in angular/angular:
* integration/bazel has been updated to use both ng_module and ts_libary with use_angular_plugin=true.
The latter is the recommended way for rules_nodejs users to compile Angular 10 with Ivy. Bazel + Angular ViewEngine is
supported with @angular/bazel <= 9.0.5 and Angular <= 8. There is still Angular ViewEngine example on rules_nodejs
https://github.com/bazelbuild/rules_nodejs/tree/stable/examples/angular_view_engine on these older versions but users
that want to update to Angular 10 and are on Bazel must switch to Ivy and at that point ts_library with
use_angular_plugin=true is more performant that ng_module. Angular example in rules_nodejs is configured this way
as well: https://github.com/bazelbuild/rules_nodejs/tree/stable/examples/angular. As an aside, we also have an
example of building Angular 10 with architect() rule directly instead of using ts_library with angular plugin:
https://github.com/bazelbuild/rules_nodejs/tree/stable/examples/angular_bazel_architect.
NB: ng_module is still required for angular/angular repository as it still builds ViewEngine & @angular/bazel
also provides the ng_package rule. ng_module can be removed in the future if ViewEngine is no longer needed in
angular repo.
* JSModuleInfo provider added to ng_module. this is for forward compat for future rules_nodejs versions.
@josephperrott, this touches `packages/bazel/src/external.bzl` which will make the sync to g3 non-trivial.
PR Close#37727
`NodeInjector` is store in expando as a list of values in an array. The
offset constant into the array have been brought together into a single
`NodeInjectorOffset` enum with better documentation explaining their usage.
PR Close#38707
`TNodeType.View` was created to support inline views. That feature did
not materialize and we have since removed the instructions for it, leave
an unneeded `TNodeType.View` which was still used in a very
inconsistent way. This change no longer created `TNodeType.View` (and
there will be a follow up chang to completely remove it.)
Also simplified the mental model so that `LView[HOST]`/`LView[T_HOST]`
always point to the insertion location of the `LView`.
PR Close#38707
Host `TNode` was passed into `getOrCreateTNode` just so that we can
compute weather or not we are a root node. This was needed because
`previousOrParentTNode` could have `TNode` from `TView` other then
current `TView`. This is confusing mental model. Previous change
ensured that `previousOrParentTNode` must always be part of `TView`,
which enabled this change to remove the unneeded argument.
PR Close#38707
`previousOrParentTNode` stores current `TNode`. Due to inconsistent
implementation the value stored would sometimes belong to the current
`TView` and sometimes to the parent. We have extra logic which accounts
for it. A better solution is to just ensure that `previousOrParentTNode`
always belongs to current `TNode`. This simplifies the mental model
and cleans up some code.
PR Close#38707
This commit creates a sample router test application to introduce the
symbol tests. It serves as a guard to ensure that any future work on the
router package does not unintentionally increase the payload size.
PR Close#38714
The `RefreshTransplantedView` flag is used to indicate that the view or one of its children
is transplanted and dirty, so it should still be refreshed as part of change detection.
This flag is set on the transplanted view itself as well setting a
counter on as its parents.
When a transplanted view is detached and still has this flag, it means
it got detached before it was refreshed. This can happen for "backwards
references" or transplanted views that are inserted at a location that
was already checked. In this case, we should decrement the parent
counters _and_ clear the flag on the detached view so it's not seen as
"transplanted" anymore (it is detached and has no parent counters to
adjust).
fixes#38619
PR Close#38768
This commit adds `ngDevMode` guard to throw some errors only in dev mode
(similar to how things work in other parts of Ivy runtime code). The
`ngDevMode` flag helps to tree-shake these error messages from production
builds (in dev mode everything will work as it works right now) to decrease
production bundle size.
PR Close#38612
`tView` that is stored on a component def contains information about directives and pipes
that are available in the scope of this component. Patching component scope causes `tView` to be
updated. Prior to this commit, the `tView` information was not restored/reset in case component
class is not declared in the `declarations` field while calling `TestBed.configureTestingModule`,
thus causing `tView` to be reused between tests (thus preserving scopes information between tests).
This commit updates TestBed logic to preserve `tView` value before applying scope changes and
reset it back to the previous state between tests.
Closes#38600.
PR Close#38659
This commit adds a guard before throwing any forms errors. This will tree-shake
error messages which cannot be minified. It should also help to reduce the
bundle size of the `forms` package in production by ~20%.
Closes#37697
PR Close#37821
Fix a bug in the HTML sanitizer where an unclosed iframe tag would
result in an escaped closing body tag as the output:
_sanitizeHtml(document, '<iframe>') => '</body>'
This closing body tag comes from the DOMParserHelper where the HTML to be
sanitized is wrapped with surrounding body tags. When an opening iframe
tag is parsed by DOMParser, which DOMParserHelper uses, everything up
until its matching closing tag is consumed as a text node. In the above
example this includes the appended closing body tag.
By removing the explicit closing body tag from the DOMParserHelper and
relying on the body tag being closed implicitly at the end, the above
example is sanitized as expected:
_sanitizeHtml(document, '<iframe>') => ''
PR Close#38454
In the Angular Package Format, we always shipped UMD bundles and previously even ES5 module output.
With V10, we removed the ES5 module output but kept the UMD ES5 output.
For this, we were able to remove our second TypeScript transpilation. Instead we started only
building ES2015 output and then downleveled it to ES5 UMD for the NPM packages. This worked
as expected but unveiled an issue in the `@angular/core` reflection capabilities.
In JIT mode, Angular determines constructor parameters (for DI) using the `ReflectionCapabilities`. The
reflection capabilities basically read runtime metadata of classes to determine the DI parameters. Such
metadata can be either stored in static class properties like `ctorParameters` or within TypeScript's `design:params`.
If Angular comes across a class that does not have any parameter metadata, it tries to detect if the
given class is actually delegating to an inherited class. It does this naively in JIT by checking if the
stringified class (function in ES5) matches a certain pattern. e.g.
```js
function MatTable() {
var _this = _super.apply(this, arguments) || this;
```
These patterns are reluctant to changes of the class output. If a class is not recognized properly, the
DI parameters will be assumed empty and the class is **incorrectly** constructed without arguments.
This actually happened as part of v10 now. Since we downlevel ES2015 to ES5 (instead of previously
compiling sources directly to ES5), the class output changed slightly so that Angular no longer detects
it. e.g.
```js
var _this = _super.apply(this, __spread(arguments)) || this;
```
This happens because the ES2015 output will receive an auto-generated constructor if the class
defines class properties. This constructor is then already containing an explicit `super` call.
```js
export class MatTable extends CdkTable {
constructor() {
super(...arguments);
this.disabled = true;
}
}
```
If we then downlevel this file to ES5 with `--downlevelIteration`, TypeScript adjusts the `super` call so that
the spread operator is no longer used (not supported in ES5). The resulting super call is different to the
super call that would have been emitted if we would directly transpile to ES5. Ultimately, Angular no
longer detects such classes as having an delegate constructor -> and DI breaks.
We fix this by expanding the rather naive RegExp patterns used for the reflection capabilities
so that downleveled pass-through/delegate constructors are properly detected. There is a risk
of a false-positive as we cannot detect whether `__spread` is actually the TypeScript spread
helper, but given the reflection patterns already make lots of assumptions (e.g. that `super` is
actually the superclass, we should be fine making this assumption too. The false-positive would
not result in a broken app, but rather in unnecessary providers being injected (as a noop).
Fixes#38453
PR Close#38463
This commit updates the code to move generated i18n statements into the `consts` field of
ComponentDef to avoid invoking `$localize` function before component initialization (to better
support runtime translations) and also avoid problems with lazy-loading when i18n defs may not
be present in a chunk where it's referenced.
Prior to this change the i18n statements were generated at the top leve:
```
var I18N_0;
if (typeof ngI18nClosureMode !== "undefined" && ngI18nClosureMode) {
var MSG_X = goog.getMsg(“…”);
I18N_0 = MSG_X;
} else {
I18N_0 = $localize('...');
}
defineComponent({
// ...
template: function App_Template(rf, ctx) {
i0.ɵɵi18n(2, I18N_0);
}
});
```
This commit updates the logic to generate the following code instead:
```
defineComponent({
// ...
consts: function() {
var I18N_0;
if (typeof ngI18nClosureMode !== "undefined" && ngI18nClosureMode) {
var MSG_X = goog.getMsg(“…”);
I18N_0 = MSG_X;
} else {
I18N_0 = $localize('...');
}
return [
I18N_0
];
},
template: function App_Template(rf, ctx) {
i0.ɵɵi18n(2, 0);
}
});
```
Also note that i18n template instructions now refer to the `consts` array using an index
(similar to other template instructions).
PR Close#38404
When removal of one view causes removal of another one from the same
ViewContainerRef it triggers an error with views length calculation. This commit
fixes this bug by removing a view from the list of available views before invoking
actual view removal (which might be recursive and relies on the length of the list
of available views).
Fixes#38201.
PR Close#38317
Fixes an error if a CSS custom property, used inside a host binding, has a
number in its name. The error is thrown because the styling parser only
expects characters from A to Z,dashes, underscores and a handful of other
characters.
Fixes#37292.
PR Close#38432
When using the safe navigation operator in a binding expression, a temporary
variable may be used for storing the result of a side-effectful call.
For example, the following template uses a pipe and a safe property access:
```html
<app-person-view [enabled]="enabled" [firstName]="(person$ | async)?.name"></app-person-view>
```
The result of the pipe evaluation is stored in a temporary to be able to check
whether it is present. The temporary variable needs to be declared in a separate
statement and this would also cause the full expression itself to be pulled out
into a separate statement. This would compile into the following
pseudo-code instructions:
```js
var temp = null;
var firstName = (temp = pipe('async', ctx.person$)) == null ? null : temp.name;
property('enabled', ctx.enabled)('firstName', firstName);
```
Notice that the pipe evaluation happens before evaluating the `enabled` binding,
such that the runtime's internal binding index would correspond with `enabled`,
not `firstName`. This introduces a problem when the pipe uses `WrappedValue` to
force a change to be detected, as the runtime would then mark the binding slot
corresponding with `enabled` as dirty, instead of `firstName`. This results
in the `enabled` binding to be updated, triggering setters and affecting how
`OnChanges` is called.
In the pseudo-code above, the intermediate `firstName` variable is not strictly
necessary---it only improved readability a bit---and emitting it inline with
the binding itself avoids the out-of-order execution of the pipe:
```js
var temp = null;
property('enabled', ctx.enabled)
('firstName', (temp = pipe('async', ctx.person$)) == null ? null : temp.name);
```
This commit introduces a new `BindingForm` that results in the above code to be
generated and adds compiler and acceptance tests to verify the proper behavior.
Fixes#37194
PR Close#37911
In JIT compiled apps, component definitions are compiled upon first
access. For a component class `A` that extends component class `B`, the
`B` component is also compiled when the `InheritDefinitionFeature` runs
during the compilation of `A` before it has finalized. A problem arises
when the compilation of `B` would flush the NgModule scoping queue,
where the NgModule declaring `A` is still pending. The scope information
would be applied to the definition of `A`, but its compilation is still
in progress so requesting the component definition would compile `A`
again from scratch. This "inner compilation" is correctly assigned the
NgModule scope, but once the "outer compilation" of `A` finishes it
would overwrite the inner compilation's definition, losing the NgModule
scope information.
In summary, flushing the NgModule scope queue could trigger a reentrant
compilation, where JIT compilation is non-reentrant. To avoid the
reentrant compilation, a compilation depth counter is introduced to
avoid flushing the NgModule scope during nested compilations.
Fixes#37105
PR Close#37795
Queries weren't matching directives that provide themselves via string
injection tokens, because the assumption was that any string passed to
a query decorator refers to a template reference.
These changes make it so we match both template references and
providers while giving precedence to the template references.
Fixes#38313.
Fixes#38315.
PR Close#38321
This commit contains no changes to code. It only breaks `i18n.ts` file
into `i18n.ts` + `i18n_apply.ts` + `i18n_parse.ts` +
`i18n_postprocess.ts` for easier maintenance.
PR Close#38368
The currently selected ICU was incorrectly being stored it `TNode`
rather than in `LView`.
Remove: `TIcuContainerNode.activeCaseIndex`
Add: `LView[TIcu.currentCaseIndex]`
PR Close#38345
This commit performs minor refactoring in Forms package to get rid of duplicate functions.
It looks like the functions were duplicated due to a slightly different type signatures, but
their logic is completely identical. The logic in retained functions remains the same and now
these function also accept a generic type to achieve the same level of type safety.
PR Close#38371
This change provides better typing for the `LView.debug` property which
is intended to be used by humans while debugging the application with
`ngDevMode` turned on.
In addition this chang also adds jasmine matchers for better asserting
that `LView` is in the correct state.
PR Close#38359
I18n code breaks up internationalization into opCodes which are then stored
in arrays. To make it easier to debug the codebase this PR adds `debug`
property to the arrays which presents the data in human readable format.
PR Close#38154
This commit creates a sample forms test application to introduce the symbol
tests. It serves as a guard to ensure that any future work on the
forms package does not unintentionally increase the payload size.
PR Close#38044
We recently reworked our `ng_rollup_bundle` rule to no longer output
ESM5 and to optimize applications properly (previously applications were
not optimized properly due to incorrect build optimizer setup).
This change meant that a lot of symbols have been removed from the
golden correctly. See: fd65958b88
Unfortunately though, a few symbols have been accidentally removed
because they are now part of the bundle as ES2015 classes which the
symbol extractor does not pick up. This commit fixes the symbol
extractor to capture ES2015 classes. We also update the golden to
reflect this change.
PR Close#38093
Currently we read lifecycle hooks eagerly during `ɵɵdefineComponent`.
The result is that it is not possible to do any sort of meta-programing
such as mixins or adding lifecycle hooks using custom decorators since
any such code executes after `ɵɵdefineComponent` has extracted the
lifecycle hooks from the prototype. Additionally the behavior is
inconsistent between AOT and JIT mode. In JIT mode overriding lifecycle
hooks is possible because the whole `ɵɵdefineComponent` is placed in
getter which is executed lazily. This is because JIT mode must compile a
template which can be specified as `templateURL` and those we are
waiting for its resolution.
- `+` `ɵɵdefineComponent` becomes smaller as it no longer needs to copy
lifecycle hooks from prototype to `ComponentDef`
- `-` `ɵɵNgOnChangesFeature` feature is now always included with the
codebase as it is no longer tree shakable.
Previously we have read lifecycle hooks from prototype in the
`ɵɵdefineComponent` so that lifecycle hook access would be monomorphic.
This decision was made before we had `T*` data structures. By not
reading the lifecycle hooks we are moving the megamorhic read form
`ɵɵdefineComponent` to instructions. However, the reads happen on
`firstTemplatePass` only and are subsequently cached in the `T*` data
structures. The result is that the overall performance should be same
(or slightly better as the intermediate `ComponentDef` has been
removed.)
- [ ] Remove `ɵɵNgOnChangesFeature` from compiler. (It will no longer
be a feature.)
- [ ] Discuss the future of `Features` as they hinder meta-programing.
Fix#30497
PR Close#35464
Fixes the following issues related to how we validate properties during JIT:
- The invalid property warning was printing `null` as the node name
for `ng-content`. The problem is that when generating a template from
`ng-content` we weren't capturing the node name.
- We weren't running property validation on `ng-container` at all.
This used to be supported on ViewEngine and seems like an oversight.
In the process of making these changes, I found and cleaned up a
few places where we were passing in `LView` unnecessarily.
PR Close#37773
One of the ivy acceptance tests currently fails in IE10. This
is because we recently added a new test that asserts that injecting
`ViewRef` results in a `NullInjectorError`.
Due to limitations in TypeScript and in polyfills for `setPrototypeOf`,
the error cannot be thrown as `ViewRef` is always considered injectable.
In reality, `ViewRef` should not be injectable, as explicitly noted
in c00f4ab2ae.
There seems no way to simulate the proper prototype chain in such
browsers that do not natively support `__proto__`, so TypeScript
and `core-js` polyfills simply break the prototype chain and
assign inherited properties directly on `ViewRef`. i.e. so that
`ViewRef.__NG_ELEMENT_ID__` exists and DI picks it up.
There is a way for TypeScript to theoretically generate proper
prototype chain in ES5 output, but they intend to only bother
about the proper prototype chain in ES6 where `setPrototypeOf`
etc. are offically standarized. See the response:
https://github.com/microsoft/TypeScript/issues/1601#issuecomment-94892833.
PR Close#37892
Currently when the `plural` or `select` keywords in an ICU contain trailing spaces (e.g. `{count, select , ...}`), these spaces are also included into the key names in ICU vars (e.g. "VAR_SELECT "). These trailing spaces are not desirable, since they will later be converted into `_` symbols while normalizing placeholder names, thus causing mismatches at runtime (i.e. placeholder will not be replaced with the correct value). This commit updates the code to trim these spaces while generating an object with placeholders, to make sure the runtime logic can replace these placeholders with the right values.
PR Close#37866
Invoking a callback registered through `ViewRef.onDestroy` throws an error, because we weren't registering it correctly in the internal data structure. These changes also remove the `storeCleanupFn` function, because it was mostly identical to `storeCleanupWithContext` and was only used in one place.
Fixes#36213.
PR Close#37543
Special DI tokens like `ChangeDetectorRef` and `ElementRef` can provide a factory via `NG_ELEMENT_ID`. The problem is that we were reading it off the token as `token[NG_ELEMENT_ID]` which will go up the prototype chain if it couldn't be found on the current token, resulting in the private `ViewRef` API being exposed, because it extends `ChangeDetectorRef`.
These changes fix the issue by guarding the property access with `hasOwnProperty`.
Fixes#36235.
PR Close#37574
Verify that HTML parsing is supported in addition to DOMParser existence.
This maybe wasn't as important before when DOMParser was used just as a
fallback on Firefox, but now that DOMParser is the default choice, we need
to be more accurate.
PR Close#36578
This commit replaces an assert with more descriptive error message that is thrown in case `<ng-template>` or `<ng-container>` is used as host element for a Component.
Resolves#35240.
PR Close#35916
Currently when bootstrapped component is being removed using `ComponentRef.destroy` or `NgModuleRef.destroy` methods, DOM nodes may be retained in the DOM tree. This commit fixes that problem by always attaching host element of the internal root view to the component's host view node, so the cleanup can happen correctly.
Resolves#36449.
PR Close#37600
Interestingly enough, our rollup bundle optimization pipeline
did not work properly before 1b827b058e5060963590628d4735e6ac83c6dfdd.
Unused declarations were not elided because build optimizer did not
consider the Angular packages as side-effect free. Build optimizer has
a hard-coded list of Angular packages that are considered side-effect
free. Though this one did not match in the old version of the rollup
bundle rule, as internal sources were resolved through their resolved
bazel-out paths. Hence build optimizer could not detect the known
Angular framework packages. Now though, since we leverage the
Bazel-idiomatic `@bazel/rollup` implementation, sources are resolved
through linked `node_modules`, and build optimizer is able to properly
detect files as side-effect free.
PR Close#37623
Refactors the `ng_rollup_bundle` rule to a macro that relies on
the `@bazel/rollup` package. This means that the rule no longer
deals with custom ESM5 flavour output, but rather only builds
prodmode ES2015 output. This matches the common build output
in Angular projects, and optimizations done in CLI where
ES2015 is the default optimization input.
The motiviation for this change is:
* Not duplicating rollup Bazel rules. Instead leveraging the official
rollup rule.
* Not dealing with a third TS output flavor in Bazel.The ESM5 flavour has the
potential of slowing down local development (as it requires compilation replaying)
* Updating the rule to be aligned with current CLI optimizations.
This also _fixes_ a bug that surfaced in the old rollup bundle rule.
Code that is unused, is not removed properly. The new rule fixes this by
setting the `toplevel` flag. This instructs terser to remove unused
definitions at top-level. This matches the optimization applied in CLI
projects. Notably the CLI doesn't need this flag, as code is always
wrapped by Webpack. Hence, the unused code eliding runs by default.
PR Close#37623
Currently Angular internally already handles `InjectionToken` as
predicates for queries. This commit exposes this as public API as
developers already relied on this functionality but currently use
workarounds to satisfy the type constraints (e.g. `as any`).
We intend to make this public as it's low-effort to support, and
it's a significant key part for the use of light-weight tokens as
described in the upcoming guide: https://github.com/angular/angular/pull/36144.
In concrete, applications might use injection tokens over classes
for both optional DI and queries, because otherwise such references
cause classes to be always retained. This was also an issue in View
Engine, but now with Ivy, this pattern became worse, as factories are
directly attached to retained classes (ultimately ending up in the
production bundle, while being unused).
More details in the light-weight token guide and in: https://github.com/angular/angular-cli/issues/16866.
Closes#21152. Related to #36144.
PR Close#37506