// main
sil @main : $@convention(c) (Int32, UnsafeMutablePointer<Optional<UnsafeMutablePointer<Int8>>>) -> Int32 {
bb0(%0 : $Int32, %1 : $UnsafeMutablePointer<Optional<UnsafeMutablePointer<Int8>>>):
  // function_ref f(op:)
  %2 = function_ref @_T04main1fyyyKcSg2op_tKF : $@convention(thin) (@owned Optional<@callee_owned () -> @error Error>) -> @error Error // user: %6
  // function_ref closure #&#8203;1 in 
  %3 = function_ref @_T04mainyyKcfU_ : $@convention(thin) () -> @error Error // user: %4
  %4 = thin_to_thick_function %3 : $@convention(thin) () -> @error Error to $@callee_owned () -> @error Error // user: %5
  %5 = enum $Optional<@callee_owned () -> @error Error>, #Optional.some!enumelt.1, %4 : $@callee_owned () -> @error Error // user: %6
  try_apply %2(%5) : $@convention(thin) (@owned Optional<@callee_owned () -> @error Error>) -> @error Error, normal bb1, error bb2 // id: %6

bb1(%7 : $()):                                    // Preds: bb0
  %8 = tuple ()                                   // user: %9
  %9 = enum $Optional<()>, #Optional.some!enumelt.1, %8 : $()
  %10 = integer_literal $Builtin.Int32, 0         // user: %11
  %11 = struct $Int32 (%10 : $Builtin.Int32)      // user: %12
  return %11 : $Int32                             // id: %12

bb2(%13 : $Error):                                // Preds: bb0
  unreachable                                     // id: %14
} // end sil function 'main'

apply expression is not marked as throwing or non-throwing
(call_expr type='()' location=<stdin>:3:6 range=[<stdin>:3:6 - line:3:25] arg_labels=op:
  (declref_expr type='((() throws -> Void)?) throws -> ()' location=<stdin>:3:6 range=[<stdin>:3:6 - line:3:6] decl=main.(file).f(op:)@<stdin>:2:6 function_ref=single)
  (tuple_expr type='(op: (() throws -> Void)?)' location=<stdin>:3:7 range=[<stdin>:3:7 - line:3:25] names=op
    (inject_into_optional implicit type='(() throws -> Void)?' location=<stdin>:3:12 range=[<stdin>:3:12 - line:3:24]
      (closure_expr type='() throws -> Void' location=<stdin>:3:12 range=[<stdin>:3:12 - line:3:24] discriminator=0
        (parameter_list range=[<stdin>:3:12 - line:3:12])
        (brace_stmt range=[<stdin>:3:12 - line:3:24]
          (throw_stmt range=[<stdin>:3:14 - line:3:22]
            (erasure_expr implicit type='Error' location=<stdin>:3:20 range=[<stdin>:3:20 - line:3:22]
              (normal_conformance type=E protocol=Error
                (value req=_domain witness=Swift.(file).Error._domain)
                (value req=_code witness=Swift.(file).Error._code)
                (value req=_userInfo witness=Swift.(file).Error._userInfo)
                (value req=_getEmbeddedNSError() witness=Swift.(file).Error._getEmbeddedNSError()))
              (call_expr type='E' location=<stdin>:3:20 range=[<stdin>:3:20 - line:3:22] nothrow arg_labels=
                (constructor_ref_call_expr type='() -> E' location=<stdin>:3:20 range=[<stdin>:3:20 - line:3:20] nothrow
                  (declref_expr implicit type='(E.Type) -> () -> E' location=<stdin>:3:20 range=[<stdin>:3:20 - line:3:20] decl=main.(file).E.init()@<stdin>:1:8 function_ref=single)
                  (type_expr type='E.Type' location=<stdin>:3:20 range=[<stdin>:3:20 - line:3:20] typerepr='E'))
                (tuple_expr type='()' location=<stdin>:3:21 range=[<stdin>:3:21 - line:3:22])))))))))