LWG 3171: restore stream insertion for filesystem::directory_entry

	* include/bits/fs_dir.h (operator<<): Overload for directory_entry,
	as per LWG 3171.
	* testsuite/27_io/filesystem/directory_entry/lwg3171.cc: New test.

From-SVN: r267238

libstdc++-v3/ChangeLog

 2018-12-18  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/fs_dir.h (operator<<): Overload for directory_entry,
+	as per LWG 3171.
+	* testsuite/27_io/filesystem/directory_entry/lwg3171.cc: New test.
+
 	* src/filesystem/std-dir.cc (filesystem::_Dir::advance): Move new
 	path instead of copying.
 

libstdc++-v3/include/bits/fs_dir.h

@@ -300,6 +300,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
     friend class directory_iterator;
     friend class recursive_directory_iterator;
 
+    // _GLIBCXX_RESOLVE_LIB_DEFECTS
+    // 3171. LWG 2989 breaks directory_entry stream insertion
+    template<typename _CharT, typename _Traits>
+      friend basic_ostream<_CharT, _Traits>&
+      operator<<(basic_ostream<_CharT, _Traits>& __os,
+		 const directory_entry& __d)
+      { return __os << __d.path(); }
+
     directory_entry(const filesystem::path& __p, file_type __t)
     : _M_path(__p), _M_type(__t)
     { }