Fix error handling in recursive_directory_iterator::increment

	* src/filesystem/dir.cc (recursive_directory_iterator::increment):
	Reset state on error.
	* testsuite/experimental/filesystem/iterators/
	recursive_directory_iterator.cc: Check state after increment error.

From-SVN: r241552

libstdc++-v3/ChangeLog

 2016-10-26  Jonathan Wakely  <jwakely@redhat.com>
 
+	* src/filesystem/dir.cc (recursive_directory_iterator::increment):
+	Reset state on error.
+	* testsuite/experimental/filesystem/iterators/
+	recursive_directory_iterator.cc: Check state after increment error.
+
 	PR libstdc++/78111
 	* src/filesystem/ops.cc (canonical): Set error for non-existent path.
 

libstdc++-v3/src/filesystem/dir.cc

@@ -343,7 +343,10 @@ fs::recursive_directory_iterator::increment(error_code& ec) noexcept
     {
       _Dir dir = open_dir(top.entry.path(), _M_options, &ec);
       if (ec)
-	return *this;
+	{
+	  _M_dirs.reset();
+	  return *this;
+	}
       if (dir.dirp)
 	  _M_dirs->push(std::move(dir));
     }

libstdc++-v3/testsuite/experimental/filesystem/iterators/recursive_directory_iterator.cc

@@ -81,6 +81,7 @@ test01()
   VERIFY( iter->path() == p/"d1/d2" );
   iter.increment(ec);  // should fail to recurse into p/d1/d2
   VERIFY( ec );
+  VERIFY( iter == fs::recursive_directory_iterator() );
 
   // Test inaccessible sub-directory, skipping permission denied.
   iter = fs::recursive_directory_iterator(p, opts, ec);