[PATCH] libstdc++/71005 fix post-increment for filesystem iterators

[Jonathan Wakely <jwakely at redhat dot com>]

Eric pointed out that the post-increment operator on filesystem
directory iterators was returning the incremented value, because the
returnedobject shared its state with the incremented iterator.

This makes post-increment return a proxy, which contains the
directory_entry value before the increment.

	PR libstdc++/71005
	* include/experimental/bits/fs_dir.h (__directory_iterator_proxy):
	New type.
	(directory_iterator::operator++(int)): Return proxy.
	(recursive_directory_iterator::operator++(int)): Likewise.
	* testsuite/experimental/filesystem/iterators/directory_iterator.cc:
	Test post-increment.
	* testsuite/experimental/filesystem/iterators/
	recursive_directory_iterator.cc: Likewise.

Tested x86_64-linux, committed to trunk. Backports to follow.

Attachment: patch.txt
Description: Text document