Fasta type inference prototype #2

pkg/front_end/lib/src/fasta/kernel/frontend_accessors.dart

Index: pkg/front_end/lib/src/fasta/kernel/frontend_accessors.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/frontend_accessors.dart b/pkg/front_end/lib/src/fasta/kernel/frontend_accessors.dart
index 61aa7919fa3648ffe5aa8d317194bba51512a04b..d96a0c86838666613e01fd29873fd5b5e94af5d7 100644
--- a/pkg/front_end/lib/src/fasta/kernel/frontend_accessors.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/frontend_accessors.dart
@@ -8,6 +8,8 @@
 /// let expressions.
 library kernel.frontend.accessors;
 
+import 'package:front_end/src/fasta/builder/shadow_ast.dart';
+import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart';
 import 'package:kernel/ast.dart';
 
 import '../names.dart' show indexGetName, indexSetName;
@@ -26,8 +28,8 @@ import '../names.dart' show indexGetName, indexSetName;
 /// called.
 abstract class Accessor {
   /// Builds an [Expression] representing a read from the accessor.
-  Expression buildSimpleRead() {
-    return _finish(_makeSimpleRead());
+  ShadowExpression buildSimpleRead() {
+    return _finish(_makeSimpleRead() as ShadowExpression);
   }
 
   /// Builds an [Expression] representing an assignment with the accessor on
@@ -36,7 +38,8 @@ abstract class Accessor {
   /// The returned expression evaluates to the assigned value, unless
   /// [voidContext] is true, in which case it may evaluate to anything.
   Expression buildAssignment(Expression value, {bool voidContext: false}) {
-    return _finish(_makeSimpleWrite(value, voidContext));
+    return _finish(_makeSimpleWrite(value, voidContext) as ShadowExpression)
+        as Expression;
   }
 
   /// Returns an [Expression] representing a null-aware assignment (`??=`) with
@@ -49,14 +52,20 @@ abstract class Accessor {
   Expression buildNullAwareAssignment(Expression value, DartType type,
       {bool voidContext: false}) {
     if (voidContext) {
-      return _finish(new ConditionalExpression(buildIsNull(_makeRead()),
-          _makeWrite(value, false), new NullLiteral(), type));
+      return _finish(new ConditionalExpression(
+          buildIsNull(_makeRead()),
+          _makeWrite(value, false),
+          new NullLiteral(),
+          type) as ShadowExpression) as Expression;
     }
     var tmp = new VariableDeclaration.forValue(_makeRead());
     return _finish(makeLet(
         tmp,
-        new ConditionalExpression(buildIsNull(new VariableGet(tmp)),
-            _makeWrite(value, false), new VariableGet(tmp), type)));
+        new ConditionalExpression(
+            buildIsNull(new VariableGet(tmp)),
+            _makeWrite(value, false),
+            new VariableGet(tmp),
+            type)) as ShadowExpression) as Expression;
   }
 
   /// Returns an [Expression] representing a compound assignment (e.g. `+=`)
@@ -67,7 +76,7 @@ abstract class Accessor {
     return _finish(_makeWrite(
         makeBinary(
             _makeRead(), binaryOperator, interfaceTarget, value, charOffset),
-        voidContext));
+        voidContext) as ShadowExpression) as Expression;
   }
 
   /// Returns an [Expression] representing a pre-increment or pre-decrement
@@ -93,7 +102,9 @@ abstract class Accessor {
         makeBinary(valueAccess(), binaryOperator, interfaceTarget,
             new IntLiteral(1), charOffset),
         true));
-    return _finish(makeLet(value, makeLet(dummy, valueAccess())));
+    return _finish(
+            makeLet(value, makeLet(dummy, valueAccess())) as ShadowExpression)
+        as Expression;
   }
 
   Expression _makeSimpleRead() => _makeRead();
@@ -106,7 +117,7 @@ abstract class Accessor {
 
   Expression _makeWrite(Expression value, bool voidContext);
 
-  Expression _finish(Expression body) => body;
+  ShadowExpression _finish(ShadowExpression body) => body;
 
   /// Returns an [Expression] representing a compile-time error.
   ///
@@ -130,7 +141,7 @@ class VariableAccessor extends Accessor {
   VariableAccessor.internal(this.variable, this.charOffset, this.promotedType);
 
   _makeRead() =>
-      new VariableGet(variable, promotedType)..fileOffset = charOffset;
+      new KernelVariableGet(variable, promotedType)..fileOffset = charOffset;
 
   _makeWrite(Expression value, bool voidContext) {
     return variable.isFinal || variable.isConst
@@ -179,7 +190,8 @@ class PropertyAccessor extends Accessor {
       ..fileOffset = charOffset;
   }
 
-  _finish(Expression body) => makeLet(_receiverVariable, body);
+  _finish(ShadowExpression body) =>
+      makeLet(_receiverVariable, body as Expression) as ShadowExpression;
 }
 
 /// Special case of [PropertyAccessor] to avoid creating an indirect access to
@@ -218,10 +230,10 @@ class NullAwarePropertyAccessor extends Accessor {
     return new PropertySet(receiverAccess(), name, value, setter);
   }
 
-  _finish(Expression body) => makeLet(
+  _finish(ShadowExpression body) => makeLet(
       receiver,
-      new ConditionalExpression(
-          buildIsNull(receiverAccess()), new NullLiteral(), body, type));
+      new ConditionalExpression(buildIsNull(receiverAccess()),
+          new NullLiteral(), body as Expression, type)) as ShadowExpression;
 }
 
 class SuperPropertyAccessor extends Accessor {
@@ -327,8 +339,9 @@ class IndexAccessor extends Accessor {
         valueVariable, makeLet(dummy, new VariableGet(valueVariable)));
   }
 
-  Expression _finish(Expression body) {
-    return makeLet(receiverVariable, makeLet(indexVariable, body));
+  ShadowExpression _finish(ShadowExpression body) {
+    return makeLet(receiverVariable, makeLet(indexVariable, body as Expression))
+        as ShadowExpression;
   }
 }
 
@@ -378,7 +391,8 @@ class ThisIndexAccessor extends Accessor {
         valueVariable, makeLet(dummy, new VariableGet(valueVariable)));
   }
 
-  Expression _finish(Expression body) => makeLet(indexVariable, body);
+  ShadowExpression _finish(ShadowExpression body) =>
+      makeLet(indexVariable, body as Expression) as ShadowExpression;
 }
 
 class SuperIndexAccessor extends Accessor {
@@ -424,8 +438,8 @@ class SuperIndexAccessor extends Accessor {
         valueVariable, makeLet(dummy, new VariableGet(valueVariable)));
   }
 
-  Expression _finish(Expression body) {
-    return makeLet(indexVariable, body);
+  ShadowExpression _finish(ShadowExpression body) {
+    return makeLet(indexVariable, body as Expression) as ShadowExpression;
   }
 }
 
@@ -462,7 +476,8 @@ class ReadOnlyAccessor extends Accessor {
 
   _makeWrite(Expression value, bool voidContext) => makeInvalidWrite(value);
 
-  Expression _finish(Expression body) => makeLet(value, body);
+  ShadowExpression _finish(ShadowExpression body) =>
+      makeLet(value, body as Expression) as ShadowExpression;
 }
 
 Expression makeLet(VariableDeclaration variable, Expression body) {