- `brew update` should try to install `curl` before `git` on older
versions of Mac OS X where it is needed for accessing modern SSL
certificates.
- We don't need an HTTP mirror for `git` because `curl` will already be
installed before it is downloaded.
- Don't recommend GCC on Mac OS X versions where it can't be built with
the default system compiler.
- Start using the Homebrew `curl` on Mac OS X versions where it is
needed as soon as it is installed.
This will use Curl’s default user agent to reduce homepage errors and
provides a function that can be used for other audits to perform
similar tests on URLs.
Clang has fully implemented OpenMP support as of LLVM 3.7, so if OpenMP
is required by a formula gcc is no longer the only choice of compiler.
Clang should be preferred over gcc because using gcc meant linking
against libstdc++, which is ABI incompatible with libc++. This may be
unnoticeable for some users, but it causes other builds to fail, e.g.
pstoedit when imagemagick was built with OpenMP. pstoedit is required
for the octave formula, so for some users this could be a significant
problem.
