`brew install > file` should not give "export CC=/foo" output on Build Failures.
Also moved the "Using clang" output to brew when BuildError is thrown as that is where it is interesting, and not if you just do `brew --env`.
Using xcrun as a proxy to execute the compiler tools is per its design. This means you can't treat ENV['CC'] as a path anymore, but I think I found the cases this was being expected and corrected them. It was not proper anyway to assume the variable was a path, it can be anything. Like a proxy. Like xcrun.
Also more thoroughly clear ENV.
This allows you to use llvm as your default compiler and keep the cc symlink
pointed at llvm, while allowing you to build forumla that requires the gcc.
Signed-off-by: Adam Vandenberg <flangy@gmail.com>
The code was sucking. To the extent that maintenance was hard. It's a lot
easier to work with code that is sensibly split at sensible boundaries. So
now it is more like that.
But the refactor is minimal. Because we don't want you to have more merge
hell than absolutely necessary.
If you merge you will need to pay attention to brew.h.rb (as it is deleted)
and bin/brew (as command logic is gone). It will be painful, but you will just
have to help git out by moving any changes around manually.
Note compatibility.rb. It ensures that any function renames or removals don't
break anything. We're pretty serious about backwards compatibility. And that's
because we encourage you to hack around with the innards. And we couldn't do
that if we would then just make stuff disappear behind your back.
