Previously we would only add @_disfavoredOverload if the only type
changed was the return type, because in any other case it is unambiguous
which overload to call. However it is still ambiguous when storing the
function as a value rather than calling the function, unless explicit
type annotations are used.
To avoid breaking any existing code, this patch adds
@_disfavoredOverload to every overload generated by @_SwiftifyImport.
rdar://151206394
Swift nodes imported from clang don't have doc comments carried over,
but IDEs are clever enough to fetch the comments from the associated
clang node. The swift node in the macro expansion from _SwiftifyImport
doesn't have a clang node directly associated with it however.
This patch adds the same comment from the clang node to the
_SwiftifyImport macro invocation node. Since the macro has access to
this node, it can easily copy over its leading trivia.
For now the comment is not altered at all, meaning @param still remains
even if the parmeter is removed.
rdar://151346977
