Error "File is not a MEX file" on Arch Linux

Hello!

I am trying to build a MEX file form a cpp code, but I always get the error "file.mexa64 is not a MEX file". This happens also with any c file (I tried with the timestwo.c example).

The only related information on the helper is about MEX Platform Compatibility, but the extension mexa64 is the correct one for my os.

I am running Matlab r2020a on Manjaro OS (Arch Linux) and using the gcc compiler (g++ for cpp), version 10.2.0 - might be this the problem? I read that the supported compiler is gcc 6.3.x but I couldn't retrieve that (super old) version so far. Also, I'd prefere not to downgrade to that version.

Any suggestion on how to fix the problem? I have no idea.

Thank you!

[Till Blaha]

Hello Alessia,

I have the exact same behaviour in R2019a running on Arch Linux. Did you find a workaround?

Kind regards

Till

[Till Blaha]

In fact: These error message is weird and I have now spent around 2 hours compiling ancient GCC's without success.. but running the function just worked! So, if probably compiled just fine and the error message might just arise during verification? Still a bit scary, but so far, everything I compiled worked.

At least, after working around another probably unrelated problem as https://nl.mathworks.com/matlabcentral/answers/103108-why-do-i-get-an-error-when-running-the-mex-file-from-a-non-standard-location-on-selinux

[Alessia Perilli]

Hello!

Sorry for the late reply...

Finally I was able to compile, after relinking some libraries and changing the call to mex into: "try mex ... ; catch; end;"

I don't remeber exactly which libraries I needed to relink but there is a lot of information on the internet about that.

Hope it helps!

Regards, Alessia

[Arnaud Benjamin]

For me, I had this error message (truncated for clarity) :

/usr/local/MATLAB/R2022b/bin/glnxa64/../../sys/os/glnxa64/libstdc++.so.6: version `GLIBCXX_3.4.29' not found

The specified libstdc++.so.6 file is shipped with matlab. What probably happened, is that my OS's gcc (being up-to-date thanks to Arch Linux repos) produced a binary .mexa64 file which requires a more recent version of the standard lib than Matlab comes supplied with.

Simply relinking the above symlink to my system's /lib/libstdc++.so.6 fixed this error. You must also restart Matlab.