idyntree and wb-toolbox conda binaries do not work on MATLAB online

[traversaro]

No description provided.

[traversaro]

If I go to MATLAB Online and execute the following code:

system('curl -LO https://github.com/conda-forge/miniforge/releases/latest/download/Miniforge3-Linux-x86_64.sh')
system('sh Miniforge3-Linux-x86_64.sh -b')
system('~/miniforge3/condabin/conda install -c robotology-staging yarp-matlab-bindings idyntree -y')
addpath('~/miniforge3/mex')
vec = iDynTree.Vector3()

This fails with error:

>> vec = iDynTree.Vector3()
Invalid MEX-file '/home/mluser/miniforge3/mex/iDynTreeMEX.mexa64': libMatlabEngine.so: cannot open shared object file: No such file or directory

Error in iDynTree.Vector3 (line 12)
        tmp = iDynTreeMEX(314, varargin{:});

The reason is that modern CMake's FindMatlab matlab_add_mex always links all the available libraries, including the libMatlabEngine.so library that is available in MATLAB, but not in MATLAB Online.

[traversaro]

The problem is also affecting BlockFactory:

system('~/miniforge3/condabin/conda install -c robotology-staging blockfactory -y')
[..]
>> system('ldd ~/miniforge3/mex/BlockFactory.mexa64')
	linux-vdso.so.1 =>  (0x00007ffc6d951000)
	libMatlabEngine.so => not found
	libMatlabDataArray.so => /MATLAB/bin/glnxa64/libMatlabDataArray.so (0x00007f7a25c14000)
	libmex.so => /MATLAB/bin/glnxa64/libmex.so (0x00007f7a25afb000)
	libmx.so => /MATLAB/bin/glnxa64/libmx.so (0x00007f7a257f0000)
	libBlockFactoryCore.so.0.8 => /home/mluser/miniforge3/mex/../lib/libBlockFactoryCore.so.0.8 (0x00007f7a25ac3000)

[traversaro]

yarp-matlab-bindings is not affected as it is using an old vendored FindMatlab CMake that does not search or link to libMatlabEngine.so.

[traversaro]

iDynTree was fixed in robotology/idyntree#840 and the fix was released in 3.0.1, now indeed iDynTree works fine in MATLAB online: