A different approach for resynthesizing enumerations.

pkg/analyzer/lib/src/dart/element/element.dart

Index: pkg/analyzer/lib/src/dart/element/element.dart
diff --git a/pkg/analyzer/lib/src/dart/element/element.dart b/pkg/analyzer/lib/src/dart/element/element.dart
index ce69476cfafa3ed2206cd394e8634832bae77a0c..eaa34d1a168752b625c634adf08d6ee481bf8521 100644
--- a/pkg/analyzer/lib/src/dart/element/element.dart
+++ b/pkg/analyzer/lib/src/dart/element/element.dart
@@ -71,6 +71,11 @@ class ClassElementImpl extends ElementImpl
   final UnlinkedClass _unlinkedClass;
 
   /**
+   * The unlinked representation of the enumeration in the summary.
+   */
+  final UnlinkedEnum _unlinkedEnum;
+
+  /**
    * A list containing all of the accessors (getters and setters) contained in
    * this class.
    */
@@ -138,6 +143,7 @@ class ClassElementImpl extends ElementImpl
    */
   ClassElementImpl(String name, int offset)
       : _unlinkedClass = null,
+        _unlinkedEnum = null,
         super(name, offset);
 
   /**
@@ -145,20 +151,21 @@ class ClassElementImpl extends ElementImpl
    */
   ClassElementImpl.forNode(Identifier name)
       : _unlinkedClass = null,
+        _unlinkedEnum = null,
         super.forNode(name);
 
   /**
    * Initialize using the given serialized information.
    */
-  ClassElementImpl.forSerialized(
-      this._unlinkedClass, CompilationUnitElementImpl enclosingUnit)
+  ClassElementImpl.forSerialized(this._unlinkedClass, this._unlinkedEnum,
+      CompilationUnitElementImpl enclosingUnit)
       : super.forSerialized(enclosingUnit);
 
   /**
    * Set whether this class is abstract.
    */
   void set abstract(bool isAbstract) {
-    assert(_unlinkedClass == null);
+    assert(_unlinkedClass == null && _unlinkedEnum == null);
     setModifier(Modifier.ABSTRACT, isAbstract);
   }
 
@@ -187,6 +194,9 @@ class ClassElementImpl extends ElementImpl
     if (_unlinkedClass != null) {
       return _unlinkedClass.codeRange?.length;
     }
+    if (_unlinkedEnum != null) {
+      return _unlinkedEnum.codeRange?.length;
+    }
     return super.codeLength;
   }
 
@@ -195,6 +205,9 @@ class ClassElementImpl extends ElementImpl
     if (_unlinkedClass != null) {
       return _unlinkedClass.codeRange?.offset;
     }
+    if (_unlinkedEnum != null) {
+      return _unlinkedEnum.codeRange?.offset;
+    }
     return super.codeOffset;
   }
 
@@ -232,6 +245,12 @@ class ClassElementImpl extends ElementImpl
           ? new SourceRange(comment.offset, comment.length)
           : null;
     }
+    if (_unlinkedEnum != null) {
+      UnlinkedDocumentationComment comment = _unlinkedEnum.documentationComment;
+      return comment != null
+          ? new SourceRange(comment.offset, comment.length)
+          : null;
+    }
     return super.docRange;
   }
 
@@ -240,6 +259,9 @@ class ClassElementImpl extends ElementImpl
     if (_unlinkedClass != null) {
       return _unlinkedClass?.documentationComment?.text;
     }
+    if (_unlinkedEnum != null) {
+      return _unlinkedEnum?.documentationComment?.text;
+    }
     return super.documentationComment;
   }
 
@@ -294,6 +316,7 @@ class ClassElementImpl extends ElementImpl
    * Set whether this class is defined by an enum declaration.
    */
   void set enum2(bool isEnum) {
+    assert(_unlinkedClass == null && _unlinkedEnum == null);
     setModifier(Modifier.ENUM, isEnum);
   }
 
@@ -383,7 +406,7 @@ class ClassElementImpl extends ElementImpl
   }
 
   void set interfaces(List<InterfaceType> interfaces) {
-    assert(_unlinkedClass == null);
+    assert(_unlinkedClass == null && _unlinkedEnum == null);
     _interfaces = interfaces;
   }
 
@@ -392,17 +415,31 @@ class ClassElementImpl extends ElementImpl
     if (_unlinkedClass != null) {
       return _unlinkedClass.isAbstract;
     }
+    if (_unlinkedEnum != null) {
+      return false;
+    }
     return hasModifier(Modifier.ABSTRACT);
   }
 
   @override
-  bool get isEnum => hasModifier(Modifier.ENUM);
+  bool get isEnum {
+    if (_unlinkedClass != null) {
+      return false;
+    }
+    if (_unlinkedEnum != null) {
+      return true;
+    }
+    return hasModifier(Modifier.ENUM);
+  }
 
   @override
   bool get isMixinApplication {
     if (_unlinkedClass != null) {
       return _unlinkedClass.isMixinApplication;
     }
+    if (_unlinkedEnum != null) {
+      return false;
+    }
     return hasModifier(Modifier.MIXIN_APPLICATION);
   }
 
@@ -447,6 +484,10 @@ class ClassElementImpl extends ElementImpl
       return _metadata ??=
           _buildAnnotations(enclosingUnit, _unlinkedClass.annotations);
     }
+    if (_unlinkedEnum != null) {
+      return _metadata ??=
+          _buildAnnotations(enclosingUnit, _unlinkedEnum.annotations);
+    }
     return super.metadata;
   }
 
@@ -457,6 +498,7 @@ class ClassElementImpl extends ElementImpl
    * Set the methods contained in this class to the given [methods].
    */
   void set methods(List<MethodElement> methods) {
+    assert(_unlinkedEnum == null);
     for (MethodElement method in methods) {
       (method as MethodElementImpl).enclosingElement = this;
     }
@@ -483,7 +525,7 @@ class ClassElementImpl extends ElementImpl
   }
 
   void set mixins(List<InterfaceType> mixins) {
-    assert(_unlinkedClass == null);
+    assert(_unlinkedClass == null && _unlinkedEnum == null);
     _mixins = mixins;
   }
 
@@ -492,6 +534,9 @@ class ClassElementImpl extends ElementImpl
     if (_unlinkedClass != null) {
       return _unlinkedClass.name;
     }
+    if (_unlinkedEnum != null) {
+      return _unlinkedEnum.name;
+    }
     return super.name;
   }
 
@@ -500,6 +545,9 @@ class ClassElementImpl extends ElementImpl
     if (_unlinkedClass != null) {
       return _unlinkedClass.nameOffset;
     }
+    if (_unlinkedEnum != null) {
+      return _unlinkedEnum.nameOffset;
+    }
     return super.nameOffset;
   }
 
@@ -519,7 +567,7 @@ class ClassElementImpl extends ElementImpl
    * [typeParameters].
    */
   void set typeParameters(List<TypeParameterElement> typeParameters) {
-    assert(_unlinkedClass == null);
+    assert(_unlinkedClass == null && _unlinkedEnum == null);
     for (TypeParameterElement typeParameter in typeParameters) {
       (typeParameter as TypeParameterElementImpl).enclosingElement = this;
     }
@@ -527,8 +575,9 @@ class ClassElementImpl extends ElementImpl
   }
 
   @override
-  List<UnlinkedTypeParam> get unlinkedTypeParams =>
-      _unlinkedClass.typeParameters;
+  List<UnlinkedTypeParam> get unlinkedTypeParams {
+    return _unlinkedClass?.typeParameters ?? const <UnlinkedTypeParam>[];
+  }
 
   @override
   ConstructorElement get unnamedConstructor {