Basic implementation of typedef member lookups (#2768)

* flatten

* Fix up typedef implementation to handle generic non-class correctly

* oops, forgot a bit

Author: jcollins-g

lib/src/model/model_element.dart

@@ -315,7 +315,10 @@ abstract class ModelElement extends Canonicalization
       if (e.aliasedType is FunctionType) {
         return FunctionTypedef(e, library, packageGraph);
       }
-      return Typedef(e, library, packageGraph);
+      if (e.aliasedType.element is ClassElement) {
+        return ClassTypedef(e, library, packageGraph);
+      }
+      return GeneralizedTypedef(e, library, packageGraph);
     }
     if (e is ConstructorElement) {
       return Constructor(e, library, packageGraph);

lib/src/model/typedef.dart

@@ -9,7 +9,7 @@ import 'package:dartdoc/src/model/comment_referable.dart';
 import 'package:dartdoc/src/model/model.dart';
 import 'package:dartdoc/src/render/typedef_renderer.dart';
 
-class Typedef extends ModelElement
+abstract class Typedef extends ModelElement
     with TypeParameters, Categorization
     implements EnclosedElement {
   Typedef(TypeAliasElement element, Library library, PackageGraph packageGraph)
@@ -40,6 +40,8 @@ class Typedef extends ModelElement
   @override
   String get filePath => '${library.dirName}/$fileName';
 
+  /// Helper for mustache templates, which can't do casting themselves
+  /// without this.
   FunctionTypedef get asCallable => this as FunctionTypedef;
 
   @override
@@ -65,34 +67,73 @@ class Typedef extends ModelElement
 
   TypedefRenderer get _renderer => packageGraph.rendererFactory.typedefRenderer;
 
-  Map<String, CommentReferable> _referenceChildren;
+  @override
+  Iterable<CommentReferable> get referenceParents => [definingLibrary];
 
+  Map<String, CommentReferable> _referenceChildren;
   @override
   Map<String, CommentReferable> get referenceChildren {
     if (_referenceChildren == null) {
       _referenceChildren = {};
-
-      // Only consider parameters if this is a function typedef.
-      if (isCallable) {
-        _referenceChildren
-            .addEntriesIfAbsent(parameters.explicitOnCollisionWith(this));
-      }
       _referenceChildren
           .addEntriesIfAbsent(typeParameters.explicitOnCollisionWith(this));
     }
     return _referenceChildren;
   }
+}
+
+/// A typedef referring to a non-function typedef that is nevertheless not
+/// referring to a defined class.  An example is a typedef alias for `void` or
+/// for `Function` itself.
+class GeneralizedTypedef extends Typedef {
+  GeneralizedTypedef(
+      TypeAliasElement element, Library library, PackageGraph packageGraph)
+      : super(element, library, packageGraph) {
+    assert(!isCallable);
+  }
+}
+
+/// A typedef referring to a non-function, defined type.
+class ClassTypedef extends Typedef {
+  ClassTypedef(
+      TypeAliasElement element, Library library, PackageGraph packageGraph)
+      : super(element, library, packageGraph) {
+    assert(!isCallable);
+    assert(modelType.modelElement is Class);
+  }
 
   @override
-  Iterable<CommentReferable> get referenceParents => [definingLibrary];
+  DefinedElementType get modelType => super.modelType;
+
+  @override
+  Map<String, CommentReferable> get referenceChildren {
+    if (_referenceChildren == null) {
+      _referenceChildren = super.referenceChildren;
+      _referenceChildren
+          .addEntriesIfAbsent(modelType.modelElement.referenceChildren.entries);
+    }
+    return _referenceChildren;
+  }
 }
 
 /// A typedef referring to a function type.
 class FunctionTypedef extends Typedef {
   FunctionTypedef(
       TypeAliasElement element, Library library, PackageGraph packageGraph)
-      : super(element, library, packageGraph);
+      : super(element, library, packageGraph) {
+    assert(isCallable);
+  }
 
   @override
   Callable get modelType => super.modelType;
+
+  @override
+  Map<String, CommentReferable> get referenceChildren {
+    if (_referenceChildren == null) {
+      _referenceChildren = super.referenceChildren;
+      _referenceChildren
+          .addEntriesIfAbsent(parameters.explicitOnCollisionWith(this));
+    }
+    return _referenceChildren;
+  }
 }

test/end2end/model_special_cases_test.dart

@@ -186,6 +186,23 @@ void main() {
         expect(referenceLookup(constructorTearoffs, 'F.new'),
             equals(MatchingLinkResult(Fnew)));
       });
+
+      test('.new works on typedefs', () {
+        expect(referenceLookup(constructorTearoffs, 'At.new'),
+            equals(MatchingLinkResult(Anew)));
+        expect(referenceLookup(constructorTearoffs, 'Bt.new'),
+            equals(MatchingLinkResult(Bnew)));
+        expect(referenceLookup(constructorTearoffs, 'Ct.new'),
+            equals(MatchingLinkResult(Cnew)));
+        expect(referenceLookup(constructorTearoffs, 'Dt.new'),
+            equals(MatchingLinkResult(Dnew)));
+        expect(referenceLookup(constructorTearoffs, 'Et.new'),
+            equals(MatchingLinkResult(Enew)));
+        expect(referenceLookup(constructorTearoffs, 'Fstring.new'),
+            equals(MatchingLinkResult(Fnew)));
+        expect(referenceLookup(constructorTearoffs, 'Ft.new'),
+            equals(MatchingLinkResult(Fnew)));
+      });
     }, skip: !_constructorTearoffsAllowed.allows(utils.platformVersion));
   });
 

test/end2end/model_test.dart

@@ -2236,7 +2236,8 @@ void main() {
     group('Linking for generalized typedef cases works', () {
       Library generalizedTypedefs;
       Typedef T0, T2, T5, T8;
-      Class C2;
+      Class C1, C2;
+      Field C1a;
 
       setUpAll(() {
         generalizedTypedefs = packageGraph.libraries
@@ -2245,7 +2246,9 @@ void main() {
         T2 = generalizedTypedefs.typedefs.firstWhere((a) => a.name == 'T2');
         T5 = generalizedTypedefs.typedefs.firstWhere((a) => a.name == 'T5');
         T8 = generalizedTypedefs.typedefs.firstWhere((a) => a.name == 'T8');
+        C1 = generalizedTypedefs.classes.firstWhere((c) => c.name == 'C1');
         C2 = generalizedTypedefs.classes.firstWhere((c) => c.name == 'C2');
+        C1a = C1.allFields.firstWhere((f) => f.name == 'a');
       });
 
       test('Verify basic ability to link anything', () {
@@ -2266,6 +2269,12 @@ void main() {
         var T5name = T5.parameters.firstWhere((t) => t.name == 'name');
         expect(referenceLookup(T5, 'name'), equals(MatchingLinkResult(T5name)));
       });
+
+      test('Verify ability to link to class members of aliased classes', () {
+        expect(referenceLookup(generalizedTypedefs, 'T8.a'),
+            equals(MatchingLinkResult(C1a)));
+        expect(referenceLookup(T8, 'a'), equals(MatchingLinkResult(C1a)));
+      });
     });
 
     group('Linking for complex inheritance and reexport cases', () {

testing/test_package_experiments/lib/constructor_tearoffs.dart

@@ -58,4 +58,4 @@ typedef NotAClass = Function;
 
 /// Mixins don't have constructors either, so disallow `M.new`.
 mixin M<T> on C {
-}
+}