This new rule validates that if a type/function/variable definition has
an ACL specifier, it is more restrictive than the containing body's
level. This is intended to lint a peculiarity of SE-0025 where it is
stated:
> The compiler should not warn when a broader level of access control is
used within a type with more restrictive access, such as internal within
a private type. This allows the designer of the type to select the
access they would use were they to make the type more widely accessible.
I think this is an anti-goal because when a type is made more open, it
should be a concious decision at that time to make it public. This is of
course an opt-in rule as well. This also has the added benefit of
linting this compiler bug: https://bugs.swift.org/browse/SR-2925
Keith Smiley
JP Simard