How to tell mex to link with the libstdc++.so.6 in /usr/lib instead of the one in the MATLAB directory?

Question

Now mex in MATLAB 2012a only officially supports gcc 4.4.6 but I want to use gcc 4.7 at my own risk. Now If I compile something with mex directly, it will complain that

/usr/lib/gcc/i686-linux-gnu/4.7/cc1plus:
/usr/local/MATLAB/R2012a/sys/os/glnx86/libstdc++.so.6:
version `GLIBCXX_3.4.15' not found
(required by /usr/lib/i386-linux-gnu/libppl_c.so.4)

/usr/lib/gcc/i686-linux-gnu/4.7/cc1plus:
/usr/local/MATLAB/R2012a/sys/os/glnx86/libstdc++.so.6:
version `GLIBCXX_3.4.15' not found
(required by /usr/lib/i386-linux-gnu/libppl.so.9)

By strings /usr/lib/i386-linux-gnu/libstdc++.so.6 | grep 'GLIBCXX' I confirm that this libstdc++.so.6 has that version string. I reviewed mexopts.sh and modified the variable $RPATH and $MLIBS in that script, but it doesn't work. So if I don't use symbolic link, where can I config the path of the libstdc++.so.6 that mex uses? Thank you.

Answer 1

/usr/lib/gcc/i686-linux-gnu/4.7/cc1plus: /usr/local/MATLAB/R2012a/sys/os/glnx86/libstdc++.so.6: version `GLIBCXX_3.4.15' not found

The problem is that when you are building with mex, it puts -L/usr/local/MATLAB/R2012a/sys/os/glnx86 on the link line, and so the linker picks up libstdc++.so from there.

If you can't convince mex to prepend -L/usr/lib/i386-linux-gnu first, then I think your only other choice is to remove /usr/local/MATLAB/R2012a/sys/os/glnx86/libstdc++.so (just rename it to e.g. libstdc++.so.bak).