Matlab does not find compatible GCC

GCC 9.3, which should be compatible with matlab R2020b, is cleary installed on my system

>> !gcc --version
gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
Copyright (C) 2019 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.

>> !gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/9/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:hsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 9.3.0-17ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-9/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,gm2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-9 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-9-HskZEa/gcc-9-9.3.0/debian/tmp-nvptx/usr,hsa --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04) 

Nevertheless, MEX can't seem to find it.

>> mex -setup C++
Error using mex
No supported compiler was found. For options, visit https://www.mathworks.com/support/compilers.

Any ideas on this?

[Walter Roberson]

What shows up for

mex -v -setup C++

Note: for anything except compiling Mex or using Simulink itself, in R2020b you need gcc 8.x -- for example for MATLAB Coder.

[Wouter Verstraelen]

Verbose mode is on.
... Looking for compiler 'g++' ...
... Executing command 'which g++' ...No.
Did not find installed compiler 'g++'.
Error using mex
No supported compiler was found. For options, visit https://www.mathworks.com/support/compilers.

[Wouter Verstraelen]

What's the difference between mex and matlab coder?

In fact, I manage to use matlab coder and test/run the c++ generated code from there, the error only appears at the very last step when the mex standalone is generated.

[Walter Roberson]

You installed gcc but not g++

sudo apt-get install g++

[Wouter Verstraelen]

Solved it, thanks!

Answer 1

[Walter Roberson]

g++ was needed

sudo apt-get install g++