YieldExpression12_es6.ts(3,6): error TS1163: A 'yield' expression is only allowed in a generator body.
YieldExpression12_es6.ts(3,12): error TS2304: Cannot find name 'foo'.


==== YieldExpression12_es6.ts (2 errors) ====
    class C {
      constructor() {
         yield foo
         ~~~~~
!!! error TS1163: A 'yield' expression is only allowed in a generator body.
               ~~~
!!! error TS2304: Cannot find name 'foo'.
      }
    }