Fix three little issues in mustachio codegen (#2491)

Fix three little issues in mustachio codegen:

* Allow duplicate types in different `@Renderer` specifications.
* Only build each render class and renderer method once; you cannot declare two
  classes or functions with the same name.
* Do not attempt to add generators for type parameters; instead, use the bound
  if it is not `dynamic`.

Author: srawlins

test/mustachio/builder_test.dart

@@ -25,7 +25,7 @@ class Context<T> {
 };
 
 const _libraryFrontMatter = '''
-@Renderer(#renderFoo, Context<Foo>(), visibleTypes: {Bar})
+@Renderer(#renderFoo, Context<Foo>(), visibleTypes: {Bar, Baz})
 library foo;
 import 'package:mustachio/annotations.dart';
 ''';
@@ -73,15 +73,19 @@ $sourceLibraryContent
     setUpAll(() async {
       writer = InMemoryAssetWriter();
       await testMustachioBuilder('''
-abstract class FooBase {
+abstract class FooBase2<T> {
+  T get generic;
+}
+abstract class FooBase<T extends Baz> extends FooBase2<T> {
   Bar get bar;
 }
-class Foo extends FooBase {
+abstract class Foo extends FooBase {
   String s1 = "s1";
   bool b1 = false;
   List<int> l1 = [1, 2, 3];
 }
 class Bar {}
+class Baz {}
 ''');
       renderersLibrary = await resolveGeneratedLibrary(writer);
       var rendererAsset = AssetId.parse('foo|lib/foo.renderers.dart');
@@ -92,11 +96,13 @@ class Bar {}
       // The render function for Foo
       expect(
           generatedContent,
-          contains('String _render_FooBase(\n'
-              '    FooBase context, List<MustachioNode> ast, Template template,'));
+          contains('String _render_FooBase<T extends Baz>(\n'
+              '    FooBase<T> context, List<MustachioNode> ast, Template template,'));
       // The renderer class for Foo
-      expect(generatedContent,
-          contains('class _Renderer_FooBase extends RendererBase<FooBase>'));
+      expect(
+          generatedContent,
+          contains(
+              'class _Renderer_FooBase<T extends Baz> extends RendererBase<FooBase<T>>'));
     });
 
     test('for Object', () {
@@ -121,6 +127,11 @@ class Bar {}
       expect(renderersLibrary.getType('_Renderer_Bar'), isNotNull);
     });
 
+    test('for a generic, bounded type found in a getter', () {
+      expect(renderersLibrary.getTopLevelFunction('_render_Baz'), isNotNull);
+      expect(renderersLibrary.getType('_Renderer_Baz'), isNotNull);
+    });
+
     test('with a property map', () {
       expect(
           generatedContent,
@@ -130,7 +141,7 @@ class Bar {}
 
     test('with a property map which references the superclass', () {
       expect(generatedContent,
-          contains('..._Renderer_FooBase.propertyMap<CT_>(),'));
+          contains('..._Renderer_FooBase.propertyMap<Baz, CT_>(),'));
     });
 
     test('with a property map with a bool property', () {
@@ -203,6 +214,7 @@ class Bar {}
     await testMustachioBuilder('''
 class Foo {}
 class Bar {}
+class Baz {}
 ''', libraryFrontMatter: '''
 @Renderer(#renderFoo, Context<Foo>())
 @Renderer(#renderBar, Context<Bar>())
@@ -229,6 +241,7 @@ class FooBase<T> {}
 class Foo<T> extends FooBase<T> {}
 class BarBase<T> {}
 class Bar<T> extends BarBase<int> {}
+class Baz {}
 ''', libraryFrontMatter: '''
 @Renderer(#renderFoo, Context<Foo>())
 @Renderer(#renderBar, Context<Bar>())
@@ -275,6 +288,7 @@ import 'package:mustachio/annotations.dart';
     await testMustachioBuilder('''
 class Foo<T extends num> {}
 class Bar {}
+class Baz {}
 ''');
     var renderersLibrary = await resolveGeneratedLibrary(writer);
 
@@ -295,13 +309,14 @@ class Bar {}
     setUpAll(() async {
       writer = InMemoryAssetWriter();
       await testMustachioBuilder('''
-class Foo {
+abstract class Foo<T> {
   static Static get static1 => Bar();
   Private get _private1 => Bar();
   void set setter1(Setter s);
   Method method1(Method m);
 }
 class Bar {}
+class Baz {}
 class Static {}
 class Private {}
 class Setter {}

tool/mustachio/codegen_runtime_renderer.dart

@@ -101,11 +101,16 @@ String _simpleResolveErrorMessage(List<String> key, String type) =>
 
     specs.forEach(_addTypesForRendererSpec);
 
+    var builtRenderers = <ClassElement>{};
+
     while (_typesToProcess.isNotEmpty) {
       var info = _typesToProcess.removeFirst();
 
       if (info.isFullRenderer) {
-        _buildRenderer(info);
+        var buildOnlyPublicFunction =
+            builtRenderers.contains(info._contextClass);
+        _buildRenderer(info, buildOnlyPublicFunction: buildOnlyPublicFunction);
+        builtRenderers.add(info._contextClass);
       }
     }
 
@@ -142,6 +147,18 @@ String _simpleResolveErrorMessage(List<String> key, String type) =>
     if (property.isPrivate || property.isStatic || property.isSetter) return;
     if (property.hasProtected || property.hasVisibleForTesting) return;
     var type = property.type.returnType;
+    if (type is TypeParameterType) {
+      var bound = (type as TypeParameterType).bound;
+      if (bound == null || bound.isDynamic) {
+        // Don't add functions for a generic type, for example
+        // `List<E>.first` has type `E`, which we don't have a specific
+        // renderer for.
+        // TODO(srawlins): Find a solution for this. We can track all of the
+        // concrete types substituted for `E` for example.
+        return;
+      }
+      type = bound;
+    }
     var isFullRenderer = _isVisibleToMustache(type.element);
 
     if (_typeSystem.isAssignableTo(type, _typeProvider.iterableDynamicType)) {
@@ -170,9 +187,8 @@ String _simpleResolveErrorMessage(List<String> key, String type) =>
 
   /// Adds [type] to the [_typesToProcess] queue, if it is not already there.
   void _addTypeToProcess(ClassElement element, {@required isFullRenderer}) {
-    var typeToProcess = _typesToProcess
-        .singleWhere((rs) => rs._contextClass == element, orElse: () => null);
-    if (typeToProcess == null) {
+    var types = _typesToProcess.where((rs) => rs._contextClass == element);
+    if (types.isEmpty) {
       var rendererInfo = _RendererInfo(element,
           isFullRenderer: isFullRenderer, public: _rendererClassesArePublic);
       _typesToProcess.add(rendererInfo);
@@ -181,11 +197,14 @@ String _simpleResolveErrorMessage(List<String> key, String type) =>
         _typeToRendererClassName[element] = rendererInfo._rendererClassName;
       }
     } else {
-      if (isFullRenderer && !typeToProcess.isFullRenderer) {
-        // This is the only case in which we update a type-to-render.
-        typeToProcess.isFullRenderer = true;
-        _typeToRenderFunctionName[element] = typeToProcess._renderFunctionName;
-        _typeToRendererClassName[element] = typeToProcess._rendererClassName;
+      for (var typeToProcess in types) {
+        if (isFullRenderer && !typeToProcess.isFullRenderer) {
+          // This is the only case in which we update a type-to-render.
+          typeToProcess.isFullRenderer = true;
+          _typeToRenderFunctionName[element] =
+              typeToProcess._renderFunctionName;
+          _typeToRendererClassName[element] = typeToProcess._rendererClassName;
+        }
       }
     }
   }
@@ -201,14 +220,19 @@ String _simpleResolveErrorMessage(List<String> key, String type) =>
     return _isVisibleToMustache(element.supertype.element);
   }
 
-  /// Builds both the render function and the renderer class for [renderer].
+  /// Builds render functions and the renderer class for [renderer].
   ///
   /// The function and the class are each written as Dart code to [_buffer].
   ///
   /// If [renderer] also specifies a `publicApiFunctionName`, then a public API
   /// function (which renders a context object using a template file at a path,
   /// rather than an AST) is also written.
-  void _buildRenderer(_RendererInfo renderer) {
+  ///
+  /// If [buildOnlyPublicFunction] is true, then the private render function and
+  /// renderer classes are not built, having been built for a different
+  /// [_RendererInfo].
+  void _buildRenderer(_RendererInfo renderer,
+      {@required bool buildOnlyPublicFunction}) {
     var typeName = renderer._typeName;
     var typeWithVariables = '$typeName${renderer._typeVariablesString}';
 
@@ -221,6 +245,8 @@ String ${renderer.publicApiFunctionName}${renderer._typeParametersString}(
 ''');
     }
 
+    if (buildOnlyPublicFunction) return;
+
     // Write out the render function.
     _buffer.writeln('''
 String ${renderer._renderFunctionName}${renderer._typeParametersString}(