Fasta type inference prototype #2

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

Index: pkg/front_end/lib/src/fasta/kernel/builder_accessors.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/builder_accessors.dart b/pkg/front_end/lib/src/fasta/kernel/builder_accessors.dart
index 8b44a31c2c7adedf7b815e2e0ed9977d8d17f32e..4e49d8a95bb7b99468095b20333ebeffe74e4620 100644
--- a/pkg/front_end/lib/src/fasta/kernel/builder_accessors.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/builder_accessors.dart
@@ -8,6 +8,7 @@ export 'frontend_accessors.dart' show wrapInvalid;
 
 import 'frontend_accessors.dart' show Accessor;
 
+import 'package:front_end/src/fasta/builder/shadow_ast.dart';
 import 'package:kernel/ast.dart';
 
 import '../errors.dart' show internalError;
@@ -40,7 +41,7 @@ abstract class BuilderHelper {
 
   Expression toSuperMethodInvocation(MethodInvocation node);
 
-  Expression toValue(node);
+  ShadowExpression toValue(node);
 
   Member lookupSuperMember(Name name, {bool isSetter: false});
 
@@ -48,15 +49,16 @@ abstract class BuilderHelper {
 
   finishSend(Object receiver, Arguments arguments, int charOffset);
 
-  Expression buildCompileTimeError(error, [int charOffset]);
+  ShadowExpression buildCompileTimeError(error, [int charOffset]);
 
   Initializer buildCompileTimeErrorIntializer(error, [int charOffset]);
 
   Expression buildStaticInvocation(Procedure target, Arguments arguments);
 
-  Expression buildProblemExpression(ProblemBuilder builder, int charOffset);
+  ShadowExpression buildProblemExpression(
+      ProblemBuilder builder, int charOffset);
 
-  Expression throwNoSuchMethodError(
+  ShadowExpression throwNoSuchMethodError(
       String name, Arguments arguments, int charOffset,
       {bool isSuper: false, isGetter: false, isSetter: false});
 }
@@ -72,7 +74,7 @@ abstract class BuilderAccessor implements Accessor {
 
   String get plainNameForWrite => plainNameForRead;
 
-  Expression buildForEffect() => buildSimpleRead();
+  ShadowExpression buildForEffect() => buildSimpleRead();
 
   Initializer buildFieldInitializer(
       Map<String, FieldInitializer> initializers) {
@@ -96,12 +98,12 @@ abstract class BuilderAccessor implements Accessor {
   /* Expression | BuilderAccessor */ buildPropertyAccess(
       IncompleteSend send, bool isNullAware) {
     if (send is SendAccessor) {
-      return buildMethodInvocation(
-          buildSimpleRead(), send.name, send.arguments, send.charOffset,
+      return buildMethodInvocation(buildSimpleRead() as Expression, send.name,
+          send.arguments, send.charOffset,
           isNullAware: isNullAware);
     } else {
-      return PropertyAccessor.make(helper, send.charOffset, buildSimpleRead(),
-          send.name, null, null, isNullAware);
+      return PropertyAccessor.make(helper, send.charOffset,
+          buildSimpleRead() as Expression, send.name, null, null, isNullAware);
     }
   }
 
@@ -172,7 +174,7 @@ abstract class CompileTimeErrorAccessor implements BuilderAccessor {
     return buildError();
   }
 
-  Expression buildSimpleRead() => buildError();
+  ShadowExpression buildSimpleRead() => buildError() as ShadowExpression;
 
   Expression makeInvalidRead() => buildError();
 
@@ -193,9 +195,9 @@ class ThisAccessor extends BuilderAccessor {
 
   String get plainNameForRead => internalError(isSuper ? "super" : "this");
 
-  Expression buildSimpleRead() {
+  ShadowExpression buildSimpleRead() {
     if (!isSuper) {
-      return new ThisExpression();
+      return new ThisExpression() as ShadowExpression;
     } else {
       return helper.buildCompileTimeError(
           "Can't use `super` as an expression.", charOffset);
@@ -286,7 +288,7 @@ class ThisAccessor extends BuilderAccessor {
   Expression buildAssignmentError() {
     String message =
         isSuper ? "Can't assign to 'super'." : "Can't assign to 'this'.";
-    return helper.buildCompileTimeError(message, charOffset);
+    return helper.buildCompileTimeError(message, charOffset) as Expression;
   }
 
   toString() => "ThisAccessor($charOffset${isSuper ? ', super' : ''})";
@@ -311,7 +313,7 @@ class IncompleteError extends IncompleteSend with CompileTimeErrorAccessor {
       : super(helper, charOffset, null);
 
   Expression buildError() {
-    return helper.buildCompileTimeError(error, charOffset);
+    return helper.buildCompileTimeError(error, charOffset) as Expression;
   }
 }
 
@@ -325,7 +327,7 @@ class SendAccessor extends IncompleteSend {
 
   String get plainNameForRead => name.name;
 
-  Expression buildSimpleRead() {
+  ShadowExpression buildSimpleRead() {
     return internalError("Unhandled");
   }
 
@@ -355,7 +357,8 @@ class SendAccessor extends IncompleteSend {
         return buildThrowNoSuchMethodError(arguments);
       }
       if (builder.hasProblem) {
-        result = helper.buildProblemExpression(builder, charOffset);
+        result =
+            helper.buildProblemExpression(builder, charOffset) as Expression;
       } else {
         Member target = builder.target;
         if (target != null) {
@@ -374,7 +377,7 @@ class SendAccessor extends IncompleteSend {
       }
     } else {
       result = buildMethodInvocation(
-          helper.toValue(receiver), name, arguments, charOffset,
+          helper.toValue(receiver) as Expression, name, arguments, charOffset,
           isNullAware: isNullAware);
     }
     return result;
@@ -414,7 +417,7 @@ class IncompletePropertyAccessor extends IncompleteSend {
 
   String get plainNameForRead => name.name;
 
-  Expression buildSimpleRead() => internalError("Unhandled");
+  ShadowExpression buildSimpleRead() => internalError("Unhandled");
 
   Expression buildAssignment(Expression value, {bool voidContext: false}) {
     return internalError("Unhandled");
@@ -454,8 +457,8 @@ class IncompletePropertyAccessor extends IncompleteSend {
       return new StaticAccessor.fromBuilder(
           helper, builder, charOffset, setter);
     }
-    return PropertyAccessor.make(helper, charOffset, helper.toValue(receiver),
-        name, null, null, isNullAware);
+    return PropertyAccessor.make(helper, charOffset,
+        helper.toValue(receiver) as Expression, name, null, null, isNullAware);
   }
 
   Expression buildNullAwareAssignment(Expression value, DartType type,
@@ -499,7 +502,7 @@ class IndexAccessor extends kernel.IndexAccessor with BuilderAccessor {
 
   Expression doInvocation(int charOffset, Arguments arguments) {
     return buildMethodInvocation(
-        buildSimpleRead(), callName, arguments, charOffset);
+        buildSimpleRead() as Expression, callName, arguments, charOffset);
   }
 
   toString() => "IndexAccessor()";
@@ -591,8 +594,8 @@ class StaticAccessor extends kernel.StaticAccessor with BuilderAccessor {
 
   Expression doInvocation(int charOffset, Arguments arguments) {
     if (readTarget == null || isFieldOrGetter(readTarget)) {
-      return buildMethodInvocation(buildSimpleRead(), callName, arguments,
-          charOffset + (readTarget?.name?.name?.length ?? 0));
+      return buildMethodInvocation(buildSimpleRead() as Expression, callName,
+          arguments, charOffset + (readTarget?.name?.name?.length ?? 0));
     } else {
       return helper.buildStaticInvocation(readTarget, arguments)
         ..fileOffset = charOffset;
@@ -615,7 +618,7 @@ class SuperPropertyAccessor extends kernel.SuperPropertyAccessor
   Expression doInvocation(int charOffset, Arguments arguments) {
     if (getter == null || isFieldOrGetter(getter)) {
       return buildMethodInvocation(
-          buildSimpleRead(), callName, arguments, charOffset);
+          buildSimpleRead() as Expression, callName, arguments, charOffset);
     } else {
       return new DirectMethodInvocation(new ThisExpression(), getter, arguments)
         ..fileOffset = charOffset;
@@ -640,7 +643,7 @@ class ThisIndexAccessor extends kernel.ThisIndexAccessor with BuilderAccessor {
 
   Expression doInvocation(int charOffset, Arguments arguments) {
     return buildMethodInvocation(
-        buildSimpleRead(), callName, arguments, charOffset);
+        buildSimpleRead() as Expression, callName, arguments, charOffset);
   }
 
   toString() => "ThisIndexAccessor()";
@@ -662,7 +665,7 @@ class SuperIndexAccessor extends kernel.SuperIndexAccessor
 
   Expression doInvocation(int charOffset, Arguments arguments) {
     return buildMethodInvocation(
-        buildSimpleRead(), callName, arguments, charOffset);
+        buildSimpleRead() as Expression, callName, arguments, charOffset);
   }
 
   toString() => "SuperIndexAccessor()";
@@ -725,8 +728,8 @@ class VariableAccessor extends kernel.VariableAccessor with BuilderAccessor {
   Expression doInvocation(int charOffset, Arguments arguments) {
     // Normally the offset is at the start of the token, but in this case,
     // because we insert a '.call', we want it at the end instead.
-    return buildMethodInvocation(buildSimpleRead(), callName, arguments,
-        charOffset + (variable.name?.length ?? 0));
+    return buildMethodInvocation(buildSimpleRead() as Expression, callName,
+        arguments, charOffset + (variable.name?.length ?? 0));
   }
 
   toString() => "VariableAccessor()";