Add data structures to AST to indicate potentially mutated variables.

pkg/analyzer/lib/dart/ast/ast.dart

Index: pkg/analyzer/lib/dart/ast/ast.dart
diff --git a/pkg/analyzer/lib/dart/ast/ast.dart b/pkg/analyzer/lib/dart/ast/ast.dart
index 8e295f2c3410800bceda00ca30cc2bbf0722e98b..57e69201eb29a7f2da7315f7bd8f7e8e619a7b4e 100644
--- a/pkg/analyzer/lib/dart/ast/ast.dart
+++ b/pkg/analyzer/lib/dart/ast/ast.dart
@@ -536,7 +536,7 @@ abstract class AstNode {
    * (either AST nodes or tokens) that make up the contents of this node,
    * including doc comments but excluding other comments.
    */
-  Iterable/*<AstNode | Token>*/ get childEntities;
+  Iterable /*<AstNode | Token>*/ get childEntities;
 
   /**
    * Return the offset of the character immediately following the last character
@@ -591,7 +591,7 @@ abstract class AstNode {
    * Use the given [visitor] to visit this node. Return the value returned by
    * the visitor as a result of visiting this node.
    */
-  dynamic /* =E */ accept/*<E>*/(AstVisitor/*<E>*/ visitor);
+  dynamic /* =E */ accept /*<E>*/ (AstVisitor /*<E>*/ visitor);
 
   /**
    * Return the most immediate ancestor of this node for which the [predicate]
@@ -3776,6 +3776,13 @@ abstract class FunctionBody extends AstNode {
   Token get keyword;
 
   /**
+   * Return additional information about local variables and parameters that
+   * are declared within this function body or any enclosing function body.
+   * Returns `null` if resolution has not yet been performed.
+   */
+  LocalVariableInfo get localVariableInfo;

[Brian Wilkerson, 2016/02/16 21:13:39]

I'm wondering whether it might not be better to avoid adding another class to
the API and to simply have a pair of methods added to FunctionBody:

bool isPotentiallyMutatedInClosure(VariableElement element)
bool isPotentiallyMutatedInScope(VariableElement element)

That would leave open the possibility of not pre-computing the whole list of
mutated elements.

[Paul Berry, 2016/02/16 21:49:47]

Good idea.  Not only does this keep the API smaller, it also prevents clients
from accidentally modifying data structures they shouldn't touch.  PTAL.

+
+  /**
    * Return the star following the 'async' or 'sync' keyword, or `null` if there
    * is no star.
    */
@@ -5215,6 +5222,27 @@ abstract class ListLiteral extends TypedLiteral {
 abstract class Literal extends Expression {}
 
 /**
+ * Additional information about local variables within a function or method
+ * produced at resolution time.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+abstract class LocalVariableInfo {
+  /**
+   * Return the set of local variables and parameters that are potentially
+   * mutated within a local function other than the function in which they are
+   * declared.
+   */
+  Set<VariableElement> get potentiallyMutatedInClosure;
+
+  /**
+   * Return the set of local variables and parameters that are potentially
+   * mutated within the scope of their declarations.
+   */
+  Set<VariableElement> get potentiallyMutatedInScope;
+}
+
+/**
  * A literal map.
  *
  * > mapLiteral ::=