The proper fix will be hopefully be in future installers, but for now you can do it yourself by running:
sudo rm -rf /Library/Developer/CommandLineTools/usr/include/c++ - Josh
For those who haven't been following the ticket, we've determined that
the problem is caused by the CLTs installer not deleting everything left
over from older versions when updating, combined with some unfortunate
logic in how clang++ constructs its include paths. Fresh CLTs
installations are therefore not affected, but ones that have been
updated over time can be.
