[PATCH 2/1] libstdc++: Add missing friend declaration to join_view::_Sentinel

[Patrick Palka]

On Thu, 5 Mar 2020, Jonathan Wakely wrote:

> On 05/03/20 11:24 -0500, Patrick Palka wrote:
> > The converting constructor of join_view::_Sentinel<true> needs to be able to
> > access the private members of join_view::_Sentinel<false>.
> > 
> > libstdc++-v3/ChangeLog:
> > 
> > 	* include/std/ranges (join_view::_Sentinel<_Const>): Befriend
> > 	join_view::_Sentinel<!_Const>.
> > 	* testsuite/std/ranges/adaptors/join.cc: Augment test.
> 
> OK.

Thanks for the review.  Unfortunately the added test fails to compile
without first a fix for PR 93978 (or alternatively, we can add -O0 to
dg-options in join.cc).