A non-Unicode document path holding '..' (/a/../\xff/d.doc) was refused,
because the native join kept the '..' while the lexical result folded it.
join_native now folds the folder's components as normalize does, so such a
document resolves as a Unicode one would, and a '..' that leaves a Unix name
holding a backslash is still caught by the comparison.
std::path sees no \??\ or \\.\ prefix and no //server/share boundary on Unix,
so the native root check let those document roots through. Resolve the link
against the lossy document path with the Unicode rules, and return the native
join only when it names the same components.
A relative link next to a document whose path is not Unicode was joined
to the document's folder natively, skipping the parsing that refuses
device and object-manager namespaces. On Windows a document path with an
unpaired surrogate under \\.\, \\?\GLOBALROOT or \??\ therefore let
the link resolve inside that namespace. The native join now refuses those
roots as resolve does for a Unicode path; drives and shares are kept.
resolve_absolute refuses a result that is not absolute on the running
platform, such as a relative link in a document that has no path yet.
It is the function to call before opening a file.
Dylan M. Taylor
aiongg