安装scikit：找不到gcc-4.2，而是使用Clang

Question

When trying to install scikit on my Mac (OS X Lion) I stumbled upon this error:

gcc-4.2 not found, using clang instead.

I searched how to fix this and it seems that the environment variable CC is not correctly set. My question now is, how can I change this and to what do I have to change this? In my /usr/lib/ I do see the g++, gcc, llvm-g++-4.2 and llvm-gcc-4.2 executables. Also when I check env I don't see the CC variable. Even when I try to export CC=gcc I don't see it with the env command.

Answer 1

There are multiple ways of doing this:

1. If you are using make to compile the sources, use the following command:

    make CC=/path/to/gcc CXX=path/to/g++ make CC=/path/to/gcc CXX=path/to/g++ install etc. 

2. You could permanently change your default compilers by:

    cd /usr/bin rm cc c++ gcc g++ ln -s gcc-4.2 cc ln -s gcc-4.2 gcc ln -s c++-4.2 c++ ln -s g++-4.2 g++ 

You should also give clang a try, though - it's not bad at all, and in many cases is known to produce equivalent or better-optimized programs than gcc .

Answer 2

If scikits is explicitly looking for gcc-4.2, it sounds like it's hardcoded in the setup procedure (bad idea imo).

I would then just go for the symlink solution; a bit different than my comment or Ramneek's answer, but pretty much the same:

sudo ln -s /usr/bin/llvm-gcc-4.2 /usr/bin/gcc-4.2

Answer 3

gcc and such shouldn't be in /usr/lib/ , but (also) in /usr/bin/ . The ones in /usr/lib/ are subdirectories, the ones in /usr/bin/ are the executables.

It may very well be that you have the libraries in those subdirectories, but not the actual executables and header files.

Have you installed the command-line tools during your XCode installation?