Users are advised to use string types and iterators instead of containers
to construct/assign/append to paths.
In v4, the support for containers is removed.
In v4 path::lexically_normal, don't generate a trailing dot element if the
original path ends with a directory separator or dot. Also omit the trailing
directory separator the normalized path ends with a dot-dot element.
Additionally, convert directory separators to preferred separators in
root name on Windows (in v3 and v4). This may be significant for UNC paths.
Appending an absolute path now results in assigning the path, as
specified in C++17. This change is made for consistency with C++
and other languages that implement path manipulation (e.g. Python).
In Boost.Filesystem v3 path appending mostly worked as a slight upgrade
of concatenation, where appending would only add directory separators
when necessary, but not consider semantics of the root name and root
directory of the appended paths. This would work well for relative paths,
but produce unexpected results for paths with root names.
In v4, we now implement appending that is aware of root name and directory
of the appendedn paths. This means that appending a path with a root name
and/or directory no longer concatenates the paths, but rather rebases the
appended path on top of the source path. In particular, if the appended path
has a root name different from the source path, the append operation will
act as assignment.
This is closer to C++20 std::filesystem but not exactly the same. The
difference is for the case when the appended path is absolute. The C++20
spec requires assignment in this case, Boost.Filesystem v4 deliberately
omits this check. This is to ensure the correct result for UNC paths on
POSIX systems, where "//net/foo" / "/bar" is expected to produce "//net/bar",
not "/bar".
As part of this work, refactored path constructors and operators for more
optimal implementation and reducing the number of overloads.
Closes https://github.com/boostorg/filesystem/issues/214.
When the path ends with a non-root directory separator, no longer
produce a trailing dot element (filename). Instead, return an empty
path.
This affects not only path iterators and path::filename, but also any
other APIs that rely on them.
Closes https://github.com/boostorg/filesystem/issues/193.
Boost.Filesystem v4 will contain breaking changes from v3 that are required
for better compatibility with C++17 std::filesystem. It will also remove
the deprecated features of v3.
Updated docs to reflect the differences between v3 and v4. Updated tests
to verify both v3 and v4 where the differences are present.
