It's common for a requirement in a protocol and an implementation of that
requirement in a protocol extension to have the same
signature. Overload resolution prefers the requirement (which
dispatches dynamically), but that was being subverted by the shadowing
rules when the protocol came from an imported module and the extension
was in the current module. Fixes rdar://problem/21739333.
Swift SVN r30598
In most cases this means adding @public to things that get serialized;
in a few cases it means using a modern public stdlib API instead of
a legacy thing I was trying to keep @internal.
Swift SVN r19350
This includes proper rules for function overloads (i.e. shadowing by type)
and allowing type lookup to find a type even if it has the same name as
a non-type.
lookupVisibleDecls does not use this behavior yet.
Swift SVN r7016
