Because Haiku has taken such an extraordinarily long time, as with a city centre that was constructed over multiple centuries we can see the clear lines of new work with new techniques and materials on top of old work done in a way that was usual at the time.
Haiku has a lot of C++ 98 code or even pre-standard C++, not least all the stuff re-used with permission from BeOS. As was usual for projects at that time many fundamental building blocks are provided rather than using a language standard. For example there's BString and BList.
Haiku also has seams of BSD code where there'd be a project to do Whatever (WiFi, TLS, drivers, etc.) "properly" in a way unique to Haiku but as a stop gap here's some BSD code until we finish our own proper solution, which of course never happens.
Haiku has a lot of C++ 98 code or even pre-standard C++, not least all the stuff re-used with permission from BeOS. As was usual for projects at that time many fundamental building blocks are provided rather than using a language standard. For example there's BString and BList.
Haiku also has seams of BSD code where there'd be a project to do Whatever (WiFi, TLS, drivers, etc.) "properly" in a way unique to Haiku but as a stop gap here's some BSD code until we finish our own proper solution, which of course never happens.