**TypeScript Version:** nightly (2.1.0-dev.20160822) **Code** ``` ts class A { protected x: "a" | "b"; } class B extends A { protected x = "b"; } ``` **Expected behavior:** Should compile without error. Code seems intuitive to me. **Actual behavior:** error TS2415: Class 'B' incorrectly extends base class. Type 'string' is not assignable to type '"a" | "b"'.