=== tests/cases/compiler/declFileOptionalInterfaceMethod.ts ===
interface X {
>X : Symbol(X, Decl(declFileOptionalInterfaceMethod.ts, 0, 0))

    f? <T>();
>f : Symbol(f, Decl(declFileOptionalInterfaceMethod.ts, 0, 13))
>T : Symbol(T, Decl(declFileOptionalInterfaceMethod.ts, 1, 8))
}