text: //// [genericDerivedTypeWithSpecializedBase2.ts]
  class A<T extends { length: number }> {
      x: T;
  }
  
  class B<U> extends A<string> {
      y: U;
  }
  
  var x: A<{ length: number; foo: number }>;
  var y: B<number>;
  x = y;  // error
  
  
  //// [genericDerivedTypeWithSpecializedBase2.js]
  var __extends = (this && this.__extends) || (function () {
      var extendStatics = function (d, b) {
          extendStatics = Object.setPrototypeOf ||
              ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
              function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
          return extendStatics(d, b);
      }
      return function (d, b) {
          extendStatics(d, b);
          function __() { this.constructor = d; }
          d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
      };
  })();
  var A = /** @class */ (function () {
      function A() {
      }
      return A;
  }());
  var B = /** @class */ (function (_super) {
      __extends(B, _super);
      function B() {
          return _super !== null && _super.apply(this, arguments) || this;
      }
      return B;
  }(A));
  var x;
  var y;
  x = y; // error
  