clang error: unknown argument: '-mno-fused-madd' (python package installation failure)

Question

I get the following error when attempting to install psycopg2 via pip on Mavericks 10.9:

clang: error: unknown argument: '-mno-fused-madd' [-Wunused-command-line-argument-hard-error-in-future]

Not sure how to proceed and have searched here and elsewhere for this particular error. Any help is much appreciated!

Here is the complete output from pip:

$ pip install psycopg2
Downloading/unpacking psycopg2
  Downloading psycopg2-2.5.2.tar.gz (685kB): 685kB downloaded
  Running setup.py (path:/private/var/folders/0z/ljjwsjmn4v9_zwm81vhxj69m0000gn/T/pip_build_tino/psycopg2/setup.py) egg_info for package psycopg2

Installing collected packages: psycopg2
  Running setup.py install for psycopg2
    building 'psycopg2._psycopg' extension
    cc -fno-strict-aliasing -fno-common -dynamic -arch x86_64 -arch i386 -g -Os -pipe -fno-common -fno-strict-aliasing -fwrapv -mno-fused-madd -DENABLE_DTRACE -DMACOSX -DNDEBUG -Wall -Wstrict-prototypes -Wshorten-64-to-32 -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch x86_64 -arch i386 -pipe -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.5.2 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090303 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I. -I/usr/local/Cellar/postgresql/9.3.3/include -I/usr/local/Cellar/postgresql/9.3.3/include/server -c psycopg/psycopgmodule.c -o build/temp.macosx-10.9-intel-2.7/psycopg/psycopgmodule.o
    clang: error: unknown argument: '-mno-fused-madd' [-Wunused-command-line-argument-hard-error-in-future]
    clang: note: this will be a hard error (cannot be downgraded to a warning) in the future
    error: command 'cc' failed with exit status 1
    Complete output from command /usr/bin/python -c "import setuptools, tokenize;__file__='/private/var/folders/0z/ljjwsjmn4v9_zwm81vhxj69m0000gn/T/pip_build_tino/psycopg2/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('
', '
'), __file__, 'exec'))" install --record /var/folders/0z/ljjwsjmn4v9_zwm81vhxj69m0000gn/T/pip-bnWiwB-record/install-record.txt --single-version-externally-managed --compile:
    running install

running build

running build_py

creating build

creating build/lib.macosx-10.9-intel-2.7

creating build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/__init__.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/_json.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/_range.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/errorcodes.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/extensions.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/extras.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/pool.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/psycopg1.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

copying lib/tz.py -> build/lib.macosx-10.9-intel-2.7/psycopg2

creating build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/__init__.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/dbapi20.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/dbapi20_tpc.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_async.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_bug_gc.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_bugX000.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_cancel.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_connection.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_copy.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_cursor.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_dates.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_extras_dictcursor.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_green.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_lobject.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_module.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_notify.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_psycopg2_dbapi20.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_quote.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_transaction.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_types_basic.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_types_extras.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/test_with.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/testconfig.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

copying tests/testutils.py -> build/lib.macosx-10.9-intel-2.7/psycopg2/tests

running build_ext

building 'psycopg2._psycopg' extension

creating build/temp.macosx-10.9-intel-2.7

creating build/temp.macosx-10.9-intel-2.7/psycopg

cc -fno-strict-aliasing -fno-common -dynamic -arch x86_64 -arch i386 -g -Os -pipe -fno-common -fno-strict-aliasing -fwrapv -mno-fused-madd -DENABLE_DTRACE -DMACOSX -DNDEBUG -Wall -Wstrict-prototypes -Wshorten-64-to-32 -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch x86_64 -arch i386 -pipe -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.5.2 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090303 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I. -I/usr/local/Cellar/postgresql/9.3.3/include -I/usr/local/Cellar/postgresql/9.3.3/include/server -c psycopg/psycopgmodule.c -o build/temp.macosx-10.9-intel-2.7/psycopg/psycopgmodule.o

clang: error: unknown argument: '-mno-fused-madd' [-Wunused-command-line-argument-hard-error-in-future]

clang: note: this will be a hard error (cannot be downgraded to a warning) in the future

error: command 'cc' failed with exit status 1

----------------------------------------
Cleaning up...
Command /usr/bin/python -c "import setuptools, tokenize;__file__='/private/var/folders/0z/ljjwsjmn4v9_zwm81vhxj69m0000gn/T/pip_build_tino/psycopg2/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('
', '
'), __file__, 'exec'))" install --record /var/folders/0z/ljjwsjmn4v9_zwm81vhxj69m0000gn/T/pip-bnWiwB-record/install-record.txt --single-version-externally-managed --compile failed with error code 1 in /private/var/folders/0z/ljjwsjmn4v9_zwm81vhxj69m0000gn/T/pip_build_tino/psycopg2

Answer 1

You can tell clang to not raise this as an error by setting the following environment variables prior compilation:

export CFLAGS=-Qunused-arguments
export CPPFLAGS=-Qunused-arguments

Then pip install psycopg2should work.

I had the same when trying to pip install lxml.

Edit: if you are installing as superuser (which will likely be the case if you are trying to append to /Library/Python/2.7/site-packages, the native Apple factory-installed Python distribution which ships with OS X, rather than to some other Python distribution which you have subsequently installed yourself), then you will need to do, as described by @Thijs Kuipers in comments below:

sudo -E pip install psycopg2

or the equivalent, for whatever other package name you may be substituting in place of psycopg2.

UPDATE [2014-05-16]: Apple has fixed this problem with updated system Pythons (2.7, 2.6, and 2.5) in OS X 10.9.3 so the workaround is no longer necessary when using the latest Mavericks and Xcode 5.1+. However, as of now, the workaround is still required for OS X 10.8.x (Mountain Lion, currently 10.8.5) if you are using Xcode 5.1+ there.