dart2dart: Preserve variable names throughout the IR.

sdk/lib/_internal/compiler/implementation/dart_backend/dart_codegen.dart

Index: sdk/lib/_internal/compiler/implementation/dart_backend/dart_codegen.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart_backend/dart_codegen.dart b/sdk/lib/_internal/compiler/implementation/dart_backend/dart_codegen.dart
index 8738ec6421d19e08451d471aba754bb729f66542..964c84819d6f6d43df7e9379494a80d16938bd46 100644
--- a/sdk/lib/_internal/compiler/implementation/dart_backend/dart_codegen.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart_backend/dart_codegen.dart
@@ -54,7 +54,6 @@ class ASTEmitter extends tree.Visitor<dynamic, Expression> {
     variables = <VariableDeclaration>[];
     statementBuffer = <Statement>[];
     seenVariables = new Set<tree.Variable>();
-    tree.Variable.counter = 0;
     variableList = new modelx.VariableList(tree.Modifiers.EMPTY);
     fallthrough = null;
     usedLabels = new Set<tree.Label>();
@@ -174,18 +173,32 @@ class ASTEmitter extends tree.Visitor<dynamic, Expression> {
     visitStatement(stmt.next);
   }
 
-  void visitAssign(tree.Assign stmt) {
-    // Synthesize an element for the variable, if necessary.
-    if (stmt.variable.element == null) {
-      stmt.variable.element = new modelx.VariableElementX(
-          stmt.variable.name,
-          ElementKind.VARIABLE,
-          functionElement,
-          variableList,
-          null);
+  String getVariableName(tree.Variable variable) {

[sigurdm, 2014/06/04 07:51:56]

Maybe move this to a getter, so the .name field is not exposed.

[asgerf, 2014/06/04 09:40:51]

Not so easy since it depends on this.variableList and this.functionElement.

[sigurdm, 2014/06/04 10:29:39]

True - my mistake

+    if (variable.element != null && variable.index == 0) {
+      return variable.element.name;
+    }
+    // FIXME(asgerf): prevent name clashes
+    String name;
+    if (variable.element != null) {
+      name = '${variable.element.name}${variable.index}';
+    } else {
+      name = 'v${variable.index}';
     }
+    // Synthesize an element for the variable
+    variable.element = new modelx.VariableElementX(
+        name,
+        ElementKind.VARIABLE,
+        functionElement,
+        variableList,
+        null);
+    variable.index = 0; // Index is relative to the new synthesized element.
+    return name;
+  }
+
+  void visitAssign(tree.Assign stmt) {
+    String name = getVariableName(stmt.variable);
     if (seenVariables.add(stmt.variable)) {
-      variables.add(new VariableDeclaration(stmt.variable.name)
+      variables.add(new VariableDeclaration(name)
                             ..element = stmt.variable.element);
     }
     statementBuffer.add(new ExpressionStatement(makeAssignment(
@@ -349,7 +362,7 @@ class ASTEmitter extends tree.Visitor<dynamic, Expression> {
   }
 
   Expression visitVariable(tree.Variable exp) {
-    return new Identifier(exp.name)
+    return new Identifier(getVariableName(exp))
                ..element = exp.element;
   }
 
@@ -366,6 +379,9 @@ class ASTEmitter extends tree.Visitor<dynamic, Expression> {
     } else if (type is TypeVariableType) {
       return new TypeAnnotation(type.name)
           ..dartType = type;
+    } else if (type is DynamicType) {
+      return new TypeAnnotation("dynamic")
+          ..dartType = type;
     } else {
       throw "Unsupported type annotation: $type";
     }