MATLAB MEX GCC archlinux

MATLAB usually requires acient gcc versions to compile MEX files (e.g. v4.9.x for R2016b). However, archlinux usually ships with the most recent version of gcc and this may results in some conflicts with linked C++ ABI.
Fortunately, archlinux AUR provides also older gcc versions (such as gcc49). The problem is that MATLAB's `mex -setup` doesn't find these additionally installed gcc versions. The solution is to go into your local mex config in:
`/home/XX/.matlab/R2016b/mex_C++_glnxa64.xml`
and replace the line
`<cmdReturns name="which g++" />`
e.g. with 
`<cmdReturns name="which g++-4.9" />`. 
Additionally, change 
`<cmdReturns name="g++ -print-file-name=libstdc++.so"`
to
`<cmdReturns name="g++-4.9 -print-file-name=libstdc++.so"`.
Then try to run `mex.getCompilerConfigurations('C++','Selected')` from MATLAB and verify the settings.
(Don't forget to the same if the mex_C xml files etc).

I had catastrophic failure with mex for C++. For some reason, the mex_C++_glnxa64.xml file didn't exist. This fixed it!

Thanks!

Dear bonanza123,

Thanks for pointing out the solution, do you also have a solution for 2018b which requires 6.3.x version? I could find all version but 6.3.x. I tried 6.5.0 but that also does not seem to work. :(