1 minute summary, no gobbledygook:
When clang sees a build line, if there is no -stdlib=Something specified, it
adds -stdlib=libstdc++ on systems up to 10.8, and -stdlib=libc++ on 10.9 and
If the older OS is set up to use -stdlib=libc++, then all these ports break,
and need painful manual shenanigans.
All this is rendered extinct if clang just defaults to add -stdlib=libc++ on
all systems, if there is no -stdlib specified on the build line.
The fix that is needed in clang to accomplish this miraculous feat is literally
one single character change.
Think of the tickets that might never need to be dealt with.
I would ask that we consider doing this once we default to libc++ on all