Posted by virantha on Mon 24 March 2014

Getting around Xcode 5.1 clang -mno-fused-madd error

Recently updated to Xcode 5.1 on my Mavericks install, and when I went to update a few Python PyPI packages like reportlab and fabric, I started hitting this error on the compile step:

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

After a little bit of googling, it seems like the workaround for now is to do the following:

ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future pip install --upgrade reportlab fabric

Note that if you've already tried to install a package that had some C extensions for speedups that did not compile, yet the non-spedup version did install, then run the following command to reinstall it with the above ARCHFLAGS prefix 1:

pip install --upgrade --reinstall PACKAGE
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