tests/cases/conformance/parser/ecmascript5/IndexSignatures/parserIndexSignature3.ts(2,5): error TS1019: An index signature parameter cannot have a question mark.


==== tests/cases/conformance/parser/ecmascript5/IndexSignatures/parserIndexSignature3.ts (1 errors) ====
    interface I {
      [a?]
        ~
!!! error TS1019: An index signature parameter cannot have a question mark.
    }