Don't serialize local variables.

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

 // Copyright (c) 2014, 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.
 
 library analyzer.src.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 3773 matching lines @@
    */
   void set labels(List<LabelElement> labels) {
     _assertNotResynthesized(serializedExecutable);
     for (LabelElement label in labels) {
       (label as LabelElementImpl).enclosingElement = this;
     }
     this._labels = labels;
   }
 
   @override
   List<LocalVariableElement> get localVariables {

[Brian Wilkerson, 2017/06/29 21:51:41]

If this method is always going to return an empty list, then can we remove
`_localVariables`?

More generally, though, I don't like the idea that one representation never has
local variable and others do. If we're removing them from the API, then it seems
like we should mark the getter as being deprecated and return an empty list from
all of the implementations. Am I missing something?

Should we remove other local elements as well (or at least mark the getters /
methods as deprecated)?

[scheglov, 2017/06/29 22:09:11]

This is an interesting question.
Now as I search to "localVariable" usages, I see that it is used only in a
couple of places.
We mostly SET it, but very rarely GET.

Tests use it pretty often, mostly to verify type inference; plus tests of
elements builders.

OK, I will try to clean up these clients first, and then we will get a change
that removes this API.

-    if (serializedExecutable != null && _localVariables == null) {
-      List<UnlinkedVariable> unlinkedVariables =
-          serializedExecutable.localVariables;
-      int length = unlinkedVariables.length;
-      if (length != 0) {
-        List<LocalVariableElementImpl> localVariables =
-            new List<LocalVariableElementImpl>(length);
-        for (int i = 0; i < length; i++) {
-          localVariables[i] = new LocalVariableElementImpl.forSerializedFactory(
-              unlinkedVariables[i], this);
-        }
-        _localVariables = localVariables;
-      } else {
-        _localVariables = const <LocalVariableElement>[];
-      }
-    }
     return _localVariables ?? const <LocalVariableElement>[];
   }
 
   /**
    * Set the local variables defined within this executable element to the given
    * [variables].
    */
   void set localVariables(List<LocalVariableElement> variables) {
     _assertNotResynthesized(serializedExecutable);
     for (LocalVariableElement variable in variables) {
@@ skipping 5259 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }