== Switching to Libc++ on older systems by default ==

Wiki page for the setup: [wiki:LibcxxOnOlderSystems Libc++ on older systems]

Tickets to be addressed:
 * [[TicketQuery(id=50448|55471|53634|56041)]]
See also:
 * [[TicketQuery(id=52000|49903)]]

cxx_stdlib might need to be one additional criteria to respect when selecting an archive site here:
* https://github.com/macports/macports-ports/blob/master/_resources/port1.0/fetch/archive_sites.tcl
* https://github.com/macports/macports-base/blob/995dde8476c48580db4f6eedfde09e90dc5e8c99/src/package1.0/portarchivefetch.tcl#L66
Then the archive site would no longer be used if anyone changes the default in macports.conf.

=== Call with Joshua

* Make cxx_stdlib to be respected in selection of archive_sites (that would prevent users from downloading binaries rev-upgrade will mark as broken anyway)
* Offer two separate sets of binary archives for the migration. That would provide a smoother transition, but could also be avoided to reduce effort spent.
  * Move existing binary archives to a subdirectory (or new binaries in a subdirectory)
  * List both archive_sites in the ports_tree for the older systems (base will select the one that matches configuration)
* Josh to file a ticket to remind us to finish up what we need to improve bootstrapping for C++11 on older systems in time for 2.5.0