Operators: passing the list of Unknowns per a const reference is dangerous
Probably replace by pass-by-value.
We could be otherwise be tempted to do something like:
auto operator =
std::make_unique<operator_type>(felt_space,
{ fluid_mass_unknown, fluid_velocity_unknown },
{ fluid_mass_unknown, fluid_velocity_unknown },
...)
which could lead to undefined behaviour.
In fact it is properly done when a std::vector
is used... but not when it is an std::array