Besides being clearer, this fixes issues with GCC 15. The latter uses
C23 by default, which changes the meaning of function declarations
without parameters such as
bool return false();
Instead of "this function takes an unknown number of arguments", this
now equals (void), that is, "this function takes no arguments". So we
run into incompatible pointer type warnings all over when using such
functions. They could be cast to (void*) but this seems the cleaner
solution for this use case.
In case a subnet is moved from one interface to another the policies can
remain as is but the route has to change. This currently doesn't happen
automatically and there is no option to update the policy or route so
removing and reinstalling the policies is the only option.
Fixes#2820.
After an interface disappeared we can't remove the policies correctly as
the name doesn't resolve to the previous index anymore.
And making the policies so specific might not provide that much benefit.
To handle the interfaces on the policies correctly would require some
changes to the child-cfg, kernel-interface etc. so they'd take interface
indices directly so we could target the policies correctly even if an
interface disappeared (or reappeared and got a new index).