FunctionDeclaration7_es6.ts(3,20): error TS2523: 'yield' expressions cannot be used in a parameter initializer.
FunctionDeclaration7_es6.ts(3,20): error TS7057: 'yield' expression implicitly results in an 'any' type because its containing generator lacks a return-type annotation.


==== FunctionDeclaration7_es6.ts (2 errors) ====
    function*bar() {
      // 'yield' here is an identifier, and not a yield expression.
      function*foo(a = yield) {
                       ~~~~~
!!! error TS2523: 'yield' expressions cannot be used in a parameter initializer.
                       ~~~~~
!!! error TS7057: 'yield' expression implicitly results in an 'any' type because its containing generator lacks a return-type annotation.
      }
    }