Generic finite element implementations rely on undefined behaviour
All 'generic' finite element implementations, i.e., those building up on the infrastructure in
dune/localfunctions/utility/ make heavy use of
reinterpret_cast breaking strict aliasing rules.
As a consequence evaluation of the basis functions leads to undefined behaviour.
For those not aware of strict aliasing errors: A typical manifestation of this is, that optimized code may silently compute wrong numbers in special cases because the compiler makes wrong assumptions on when to sync register values with memory.