fix(Core): correctly treat optional pipe dependencies as optional

Previously the `@Optional()` annotation used to mark injected dependencies as
optional was ignored on pipes, meaning a "No provider found ..." error would be
thrown when attempting to instantiate a pipe with a missing optional dependency.

Fixes #1665.

PiperOrigin-RevId: 222314430

_tests/test/regression/1665_optional_pipe_dependency_test.dart

@@ -0,0 +1,33 @@
+@TestOn('browser')
+import 'package:test/test.dart';
+import 'package:angular/angular.dart';
+import 'package:angular_test/angular_test.dart';
+
+import '1665_optional_pipe_dependency_test.template.dart' as ng;
+
+void main() {
+  tearDown(disposeAnyRunningTest);
+
+  test('a missing @Optional() pipe dependency does not throw', () async {
+    var testBed = NgTestBed.forComponent(ng.TestComponentNgFactory);
+    expect(testBed.create(), completes);
+  });
+}
+
+abstract class TestService {}
+
+@Pipe('test')
+class TestPipe {
+  TestPipe(@Optional() TestService _);
+
+  dynamic transform(dynamic value) => value;
+}
+
+@Component(
+  selector: 'test',
+  template: '{{value | test}}',
+  pipes: [TestPipe],
+)
+class TestComponent {
+  var value = 'Hello world!';
+}

angular/CHANGELOG.md

@@ -84,7 +84,13 @@
     Previously, this would build successfully but emit code that instantiated
     the directive with `dynamic` in place of the private type.
 
+*   [#1665][]: `@Optional()` dependencies of pipes are now correctly treated as
+    optional. Previously the annotation was ignored, and attempting to
+    instantiate the pipe with a missing optional dependency would throw an error
+    for the missing dependency.
+
 [#1653]: https://github.com/dart-lang/angular/issues/1653
+[#1665]: https://github.com/dart-lang/angular/issues/1665
 
 ## 5.1.0
 

angular/lib/src/compiler/view_compiler/compile_view.dart

@@ -1158,7 +1158,7 @@ class CompileView implements AppViewBuilder {
         return o.ReadClassMemberExpr('ref');
       }
       usesInjectorGet = true;
-      return injectFromViewParentInjector(this, diDep.token, false);
+      return injectFromViewParentInjector(this, diDep.token, diDep.isOptional);
     }).toList();
     final pipeInstance = storage.allocate(
       name,