These have been around for some time.

This will compile for both a UNO and a DUE.

This will not compile with an error when compiled for a DUE.

c:\Users\john\Documents\Arduino\libraries\BoostForArduino\src/boost/functional/hash/detail/hash_float.hpp:96:41

error: non-constant in-class initialization invalid for static member 'boost::hash_detail::enable_binary_hash<long double, 24u, 128u>::value'

I do not think this error happened before.

I did give up on AVR examples.