* include/experimental/bits/fs_path.h (__is_path_src)
(_S_range_begin, _S_range_end): Overload to treat string_view as a
Source object.
(path::operator+=, path::compare): Overload for basic_string_view.
* testsuite/experimental/filesystem/path/construct/string_view.cc:
New test.
* testsuite/experimental/filesystem/path/construct/
string_view_cxx17.cc: New test.
From-SVN: r241658
