TYPE MISMATCH IN ARGUMENT 0 OF APPLY AT expression at [<REPL>:12:1 - line:12:15] RangeText="c.doSomething()" argument value: %13 = open_existential_addr immutable_access %6 : $*SomeChild to $*@opened("25C7E87E-2911-11E8-A83E-0242AC110002") SomeChild // user: %14 parameter type: $@opened("25C7E87E-2911-11E8-A83E-0242AC110002") SomeChild