Compiler error trying to install Astropy

[shj.wallstrom@…]

I've been trying to install py27-astropy for days now, to no avail, despite frantic googling. I get the following error: "Error: org.macports.build for port py27-astropy returned: command execution failed Please see the log file for port py27-astropy for details:

/opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_python_py-astropy/py27-astropy/main.log"

Checking the log file tells me (eventually): ":info:build Compiler specified by CC environment variable :info:build (/usr/bin/llvm-gcc-4.2:i686-apple-darwin11-llvm-gcc-4.2 (GCC) 4.2.1 (Based on App$ :info:build Copyright (C) 2007 Free Software Foundation, Inc. :info:build This is free software; see the source for copying conditions. There is NO :info:build warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.) will fail to compile ast$ :info:build Please set CC=clang and try again. :info:build You can do this, for example, by running: :info:build :info:build CC=clang python setup.py <command> :info:build :info:build where <command> is the command you ran. :info:build :info:build Command failed: cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org$ :info:build Exit code: 1 :error:build org.macports.build for port py27-astropy returned: command execution failed"

from which I gather I need the compiler clang. I did not appear to have this, so I installed it via macports and now have "clang-3.4 @3.4.2_9+analyzer+arm_runtime (active)" but the error persists. So how do I tell macports to use a different compiler in this case?