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Incompatible gcc version with mex

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Andréas Sundström
Andréas Sundström on 26 Jun 2018
Commented: Mohamad Qadri on 16 Sep 2020
I run Ubuntu 18.04. When I try to compile files with mex, I get the error message saying that mex requires version 6.3.x of gcc, whereas the default gcc version on 18.04 is 7.3.
So far so good, I try to get my hands on an older version of gcc, but all i can find through the supported repositories is gcc version 6.4. The only way I seem to be able to get specifically version 6.3 is by manually compiling and installing gcc, but frankly, I do not want to go down that rabbit hole.
I have seen your answer regarding why you don't always support the latest gcc version, but can you please at least offer support for the latest version of gcc 6 (i.e. 6.4.x)?
  1 Comment
David Young
David Young on 22 Aug 2018
It would be very helpful to have some advice on what to do about this. I also don't want to have to compile gcc from sources, but I now have a system with gcc 5.4 and gcc 6.4 both installed, and I can't guess which I should try to use to compile mex files.
It's really very puzzling that the compiler needed for MATLAB isn't actually supported.

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Answers (11)

Maria Geffen
Maria Geffen on 26 Sep 2018
I have the same issue with 2018b... sure enough, it also only supports gcc-6.3.x... this is absolutely maddening.

Victor on 8 Apr 2019
Can you share how to compile mex files with gcc 8.2.0? Thanks
  1 Comment
Michal on 8 Apr 2019
I am afraid that there is no simple way how to reliably compile mex files on Ubuntu 18.10 with gcc 8.2.0 ... :(
This is terrible situation, because Ubuntu 18.10 is officially supported OS (see here and here ), but the only officially recomended way is via additional installation of gcc 6.3 (???!!!), which is on Ubuntu 18.10 very complicated or nearly impossible task, because only version gcc-6.4 is available in official Ubuntu repos (see here).
This is the main reason why I switch from Ubuntu to Debian 9 (stable) based distros (MX Linux 18, in my case).

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Ladislav Dobrovsky
Ladislav Dobrovsky on 29 May 2020
Edited: Ladislav Dobrovsky on 3 Jul 2020
EDIT, debian package: I have made a .deb package wich installs gcc-6.3 and does not destroy the main gcc installation:
I have compiled GCC 6.3 inside Virtualbox VM in Ubuntu 16 as gcc-6.3; then copied it back to my linux mint 19.3 (ubuntu 18) and did "make install" and also copied a shared object of a library that was in different version.
It works even with nvcc for cuda.
Michal on 2 Jun 2020
Edited: Michal on 2 Jun 2020
@Ladislav Dobrovsky Python integration with MATLAB looks interesting, but ...
1. well coded MEX file is still excellent way how to significantly speed up the standard MATLAB.
2. Python + MATLAB is still more about info Googling than about real programming
And moreover, regarding support of older (and latest) RHEL: see, there is none standard package for gcc-6.3 , too ??!! Same situation on Debian, Ubuntu, etc. This is a mysterious compatibility reason from the TMW, that only one "recommanded" compiler is not available even for RHEL or other officially supporeted Linux distros. So, what ... ???
Ladislav Dobrovsky
Ladislav Dobrovsky on 30 Jun 2020
I have made a .deb package wich installs gcc-6.3 and does not destroy the main gcc installation:

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Robert on 26 Jun 2018
Edited: Robert on 26 Jun 2018
I agree, Mathworks should have updated 2018a , at the very least, to gcc-6.4 at time of its release, which is was a bug fix to gcc-6.3, the only way to get 6.3 now is to a) compile it yourself, or b) use an old archive repository or .deb file. I have not tried the prerelease 2018b, I wonder what gcc version it supports?

Michal on 1 Jul 2018
Frankly speaking I do not understand why TMW choose the "compatible" compiler version on Linux so terribly. On many distributions officially supported by Matlab is very difficult to install "compatible" gcc version.
On the other hand, in most cases the incompatibility mex warning message has no impact on functionality.
  1 Comment
Andréas Sundström
Andréas Sundström on 2 Jul 2018
To be more specific, I'm trying to build and install the Matlab wrapper for Adios. There, I get nothing out except this incompatibility warning and an error.

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Patrick Amy
Patrick Amy on 2 Oct 2018
I actually built and installed gcc-6.3 from source after much effort, but I get an error that mex can't find gcc-6.3 for C++ compiling, only for C compiling. So when I run:
>> mex -setup C++ Error using mex No supported compiler was found. For options, visit
However, when I run
> mex -setup -v Verbose mode is on. ... Looking for compiler 'gcc' ... ... Executing command 'which gcc' ...Yes ('/usr/bin/gcc'). ... Executing command 'gcc' ...Yes ('/usr/lib64/'). Found installed compiler 'gcc'. ... Looking for compiler 'gcc' ... ... Executing command 'which gcc' ...Yes ('/usr/bin/gcc'). ... Executing command 'gcc' ...Yes ('/usr/lib64/'). Found installed compiler 'gcc'. MEX configured to use 'gcc' for C language compilation.
I know my computer is using gcc-6.3 because when I check the version in the terminal I get
gcc (GCC) 6.3.0 Copyright (C) 2016 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Could Matlab just not know where to look for the compiler? I already add the /bin file with gcc in it to the path and set the environment variables and what not.
Darun Barazanchy
Darun Barazanchy on 6 Aug 2019
Can you post you gcc version somewhere? I am trying to built gcc 6.3, but I get error after error! It is extremely disappointing that MATLAB can't support a more recent version of gcc!!! Terrible
Ladislav Dobrovsky
Ladislav Dobrovsky on 3 Jun 2020
the setup is not good, you can set which GCC to use for the actual compilation call:
mex GCC='/usr/local/bin/gcc-6.3' arrayProduct.cpp

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Alexander Kristensen
Alexander Kristensen on 12 Mar 2019
Edited: Alexander Kristensen on 12 Mar 2019
I have a similar issue.
Compiling mex files works fine with current gcc compiler (gcc 8.2.0 on Ubuntu 18.10, MATLAB 2018b) but throws a warning message.
However if I try and use mexcuda it throws an error of incompatibility.
"Error using mex.
no supported compiler was found. For options. visit ..."
But installing the gcc 6.3.x is quite tedious, especially for someone with no experience in that area.
I hope for more assistance for Linux users.

Adam Hyler
Adam Hyler on 23 Sep 2019
Xingang Li
Xingang Li on 9 Apr 2020
This also worked for me and the repository is still available.

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Po-Hsuan Huang
Po-Hsuan Huang on 3 Mar 2020
I just wrote Matlab a service request. Hopefully they will respond to this thread. Have anyone tried to contact Matlab ? Did they reply ?
I will update if I hear back from them.
  1 Comment
Michal on 3 Mar 2020
Yes, I tried to contact matlab by service request ... No solution!!!
Just proposal to install supported version of compiler, which is nearly (or completely) impossible from official Ubuntu repositories.

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BRSC User on 6 Apr 2020
I also get tons of error when attempt to use locally developed C++/C based source code with matlab with mex / mexFunction. Look forward for any update form Mathworks OR other netizens for success.
Ladislav Dobrovsky
Ladislav Dobrovsky on 30 Jun 2020
I have made a .deb package wich installs gcc-6.3 and does not destroy the main gcc installation:
Mohamad Qadri
Mohamad Qadri on 16 Sep 2020
Thanks Ladislav, the package works great

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ma la
ma la on 11 Sep 2020
A work arround which seems to work in some cases is to use octave to compile the mex.
I am realy surprised that is does, and I have no idea of the limitation or the limits of that workarround. Currently, I compile the mex code with the ubuntu (20.04 LTS) version of octace and then run the code from matlab. I would always recommend to first run an example with known results to validate that the code is actually performing as expected.


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