Use DartEditBuilder to write types and remove dead code

pkg/analyzer_plugin/lib/src/utilities/change_builder/change_builder_dart.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 468 matching lines @@
       {bool addSupertypeProposals: false,
       String groupName,
       ExecutableElement methodBeingCopied,
       bool required: false}) {
     if (type != null && !type.isDynamic) {
       _EnclosingElementFinder finder = new _EnclosingElementFinder();
       finder.find(dartFileEditBuilder.unit, offset);
       String typeSource = _getTypeSource(
           type, finder.enclosingClass, finder.enclosingExecutable,
           methodBeingCopied: methodBeingCopied);
-      if (typeSource != 'dynamic') {
+      if (typeSource.isNotEmpty && typeSource != 'dynamic') {
         if (groupName != null) {
           addLinkedEdit(groupName, (LinkedEditBuilder builder) {
             write(typeSource);
             if (addSupertypeProposals) {
               _addSuperTypeProposals(builder, type, new Set<DartType>());
             }
           });
         } else {
           write(typeSource);
         }
@@ skipping 450 matching lines @@
     if (type is TypeParameterType) {
       TypeParameterElement parameterElement = type.element;
       Element parameterParent = parameterElement.enclosingElement;
       // TODO(brianwilkerson) This needs to compare the parameterParent with
       // each of the parents of the enclosingElement. (That means that we only
       // need the most closely enclosing element.)
       return parameterParent == enclosingExecutable ||
           parameterParent == enclosingClass ||
           parameterParent == methodBeingCopied;
     }
+    Element element = type.element;
+    if (element == null) {
+      return true;
+    }
+    LibraryElement definingLibrary = element.library;
+    LibraryElement importingLibrary = dartFileEditBuilder.unit.element.library;
+    if (definingLibrary != null && definingLibrary != importingLibrary) {
+      if (element.isPrivate) {
+        return false;
+      }
+    }
     return true;
   }
 }
 
 /**
  * A [FileEditBuilder] used to build edits for Dart files.
  */
 class DartFileEditBuilderImpl extends FileEditBuilderImpl
     implements DartFileEditBuilder {
   /**
@@ skipping 38 matching lines @@
     _replaceReturnTypeWithFuture(body, typeProvider);
   }
 
   @override
   DartEditBuilderImpl createEditBuilder(int offset, int length) {
     return new DartEditBuilderImpl(this, offset, length);
   }
 
   @override
   void finalize() {
-    _addLibraryImports(
-        changeBuilder.sourceChange, unit.element.library, librariesToImport);
+    CompilationUnitElement unitElement = unit.element;
+    LibraryElement libraryElement = unitElement.library;
+    CompilationUnitElement definingUnitElement =
+        libraryElement.definingCompilationUnit;
+    if (definingUnitElement == unitElement) {
+      _addLibraryImports(libraryElement, librariesToImport);
+    } else {
+      (changeBuilder as DartChangeBuilder).addFileEdit(
+          definingUnitElement.source.fullName, (DartFileEditBuilder builder) {
+        (builder as DartFileEditBuilderImpl)
+            ._addLibraryImports(libraryElement, librariesToImport);
+      });
+    }
   }
 
   @override
   void importLibraries(Iterable<Source> libraries) {
     librariesToImport.addAll(libraries);
   }
 
   @override
   void replaceTypeWithFuture(
       TypeAnnotation typeAnnotation, TypeProvider typeProvider) {
@@ skipping 14 matching lines @@
     }
     // prepare code for the types
     addReplacement(range.node(typeAnnotation), (EditBuilder builder) {
       if (!(builder as DartEditBuilder).writeType(futureType)) {
         builder.write('void');
       }
     });
   }
 
   /**
-   * Adds edits to the given [change] that ensure that all the [libraries] are
-   * imported into the given [targetLibrary].
+   * Adds edits ensure that all the [libraries] are imported into the given
+   * [targetLibrary].
    */
-  void _addLibraryImports(SourceChange change, LibraryElement targetLibrary,
-      Set<Source> libraries) {
+  void _addLibraryImports(LibraryElement targetLibrary, Set<Source> libraries) {
     // Prepare information about existing imports.
     LibraryDirective libraryDirective;
     List<ImportDirective> importDirectives = <ImportDirective>[];
     for (Directive directive in unit.directives) {
       if (directive is LibraryDirective) {
         libraryDirective = directive;
       } else if (directive is ImportDirective) {
         importDirectives.add(directive);
       }
     }
@@ skipping 297 matching lines @@
   }
 }
 
 class _InsertionDescription {
   final int offset;
   final bool insertEmptyLineBefore;
   final bool insertEmptyLineAfter;
   _InsertionDescription(
       this.offset, this.insertEmptyLineBefore, this.insertEmptyLineAfter);
 }