==== tests/cases/compiler/classExtendsValidConstructorFunction.ts (1 errors) ====
    function foo() { }
    
    var x = new foo(); // can be used as a constructor function
    
    class C extends foo { } // error, cannot extend it though
                    ~~~
!!! classExtendsValidConstructorFunction.ts(5,17): error TS2095: Could not find symbol 'foo'.