Implement type inference for assignments to a static variable.

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

 // Copyright (c) 2017, 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.
 
 /// This file declares a "shadow hierarchy" of concrete classes which extend
 /// the kernel class hierarchy, adding methods and fields needed by the
 /// BodyBuilder.
 ///
 /// Instances of these classes may be created using the factory methods in
 /// `ast_factory.dart`.
@@ skipping 1431 matching lines @@
 }
 
 /// Common base class for shadow objects representing statements in kernel
 /// form.
 abstract class KernelStatement extends Statement {
   /// Calls back to [inferrer] to perform type inference for whatever concrete
   /// type of [KernelStatement] this is.
   void _inferStatement(KernelTypeInferrer inferrer);
 }
 
+/// Concrete shadow object representing an assignment to a static variable.
+class KernelStaticAssignment extends KernelComplexAssignment {
+  KernelStaticAssignment(Expression rhs) : super(rhs);
+
+  @override
+  DartType _inferExpression(
+      KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
+    typeNeeded = inferrer.listener.staticAssignEnter(desugared, typeContext) ||
+        typeNeeded;
+    // TODO(paulberry): record the appropriate types on let variables and
+    // conditional expressions.
+    DartType writeContext;
+    var write = this.write;
+    if (write is StaticSet) {
+      writeContext = write.target.setterType;
+    }
+    var inferredType = _inferRhs(inferrer, writeContext);
+    inferrer.listener.staticAssignExit(desugared, inferredType);
+    return inferredType;
+  }
+}
+
 /// Concrete shadow object representing a read of a static variable in kernel
 /// form.
 class KernelStaticGet extends StaticGet implements KernelExpression {
   KernelStaticGet(Member target) : super(target);
 
   @override
   void _collectDependencies(KernelDependencyCollector collector) {
     // A simple or qualified identifier referring to a top level function,
     // static variable, field, getter; or a static class variable, static getter
     // or method; or an instance method; has the inferred type of the referent.
@@ skipping 653 matching lines @@
   }
 
   transformChildren(v) {
     return internalError("Internal error: Unsupported operation.");
   }
 
   visitChildren(v) {
     return internalError("Internal error: Unsupported operation.");
   }
 }