That’s one of the reasons why “forward headers” are a much better pattern than manually declaring things everywhere. One person saying “struct X;” and another

That’s one of the reasons why “forward headers” are a much better pattern than manually declaring things everywhere. One person saying “struct X;” and another saying “class X;” is a compiler error when the inconsistency is found, and it gets worse when namespaces change, etc. Just push the maintainer to handle this (e.g. <iosfwd>).