The worst thing in modern C++ is metaprogramming. It's powerful technique, but the syntax is awful, programs are unreadable & unmaintainable. Moreover, compilers don't help with debugging such code, diagnostics messages rarely tell anything useful. Not to mention frequent ICEs, at least in MSVC. :)
As a programmer who already knew functional programming and have some experience in SML and Ocaml, I found C++-functional-programming really annoying.
As a programmer who already knew functional programming and have some experience in SML and Ocaml, I found C++-functional-programming really annoying.