Implement type inference for assignments to a static variable.

pkg/front_end/testcases/inference/infer_assign_to_static.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.
+
+/*@testedFeatures=inference*/
+library test;
+
+class A {}
+
+class B extends A {
+  A operator +(C v) => null;
+  B operator -(int i) => null;
+  B operator *(B v) => null;
+  C operator &(A v) => null;
+
+  static B staticVariable;
+}
+
+class C extends B {}
+
+T f<T>() => null;
+
+B topLevelVariable;
+
+void test_topLevelVariable() {
+  topLevelVariable = /*@typeArgs=B*/ f();
+  topLevelVariable ??= /*@typeArgs=B*/ f();
+  topLevelVariable += /*@typeArgs=dynamic*/ f();
+  topLevelVariable *= /*@typeArgs=dynamic*/ f();
+  topLevelVariable &= /*@typeArgs=dynamic*/ f();
+  --topLevelVariable;
+  topLevelVariable--;
+  var /*@type=B*/ v1 = topLevelVariable = /*@typeArgs=B*/ f();
+  var /*@type=B*/ v2 = topLevelVariable ??= /*@typeArgs=B*/ f();
+  var /*@type=A*/ v3 = topLevelVariable += /*@typeArgs=dynamic*/ f();
+  var /*@type=B*/ v4 = topLevelVariable *= /*@typeArgs=dynamic*/ f();
+  var /*@type=C*/ v5 = topLevelVariable &= /*@typeArgs=dynamic*/ f();
+  var /*@type=B*/ v6 = --topLevelVariable;
+  var /*@type=B*/ v7 = topLevelVariable--;
+}
+
+void test_staticVariable() {
+  B.staticVariable = /*@typeArgs=B*/ f();
+  B.staticVariable ??= /*@typeArgs=B*/ f();
+  B.staticVariable += /*@typeArgs=dynamic*/ f();
+  B.staticVariable *= /*@typeArgs=dynamic*/ f();
+  B.staticVariable &= /*@typeArgs=dynamic*/ f();
+  --B.staticVariable;
+  B.staticVariable--;
+  var /*@type=B*/ v1 = B.staticVariable = /*@typeArgs=B*/ f();
+  var /*@type=B*/ v2 = B.staticVariable ??= /*@typeArgs=B*/ f();
+  var /*@type=A*/ v3 = B.staticVariable += /*@typeArgs=dynamic*/ f();
+  var /*@type=B*/ v4 = B.staticVariable *= /*@typeArgs=dynamic*/ f();
+  var /*@type=C*/ v5 = B.staticVariable &= /*@typeArgs=dynamic*/ f();
+  var /*@type=B*/ v6 = --B.staticVariable;
+  var /*@type=B*/ v7 = B.staticVariable--;
+}
+
+main() {}