Why can't MEX find a supported compiler in MATLAB R2016a after I upgraded to Xcode 9.4.1?

I installed Xcode 9.4.1 on my Mac and tried to use MEX. I receive the following error at the MATLAB command prompt:

 >> mex -setup
 Error using mex
 No supported compiler or SDK was found. For options, visit
 http://www.mathworks.com/support/compilers/R2016a/maci64.html

Why does MATLAB not recognize the Xcode 9.4.1 installation on my Mac?

The problem is that I can use it before, but after I have ran the code 'ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null' to install GSL, I can not use mex on Matlab normally anymore.

Please help me!

Answer 1

[Rik]

Because Xcode 9 is not explicitly mentioned in the list of supported compilers for R2016a, you have no guarantee it will work. Apparently it doesn't, so either you'll have to upgrade Matlab to one that will work with the new version of Xcode, or you'll have to downgrade Xcode again to 7.x.

[Wang Yankai]

Thank you in advance! But I just downgraded Xcode again to 7.x, it still not works.

[Rik]

Did you already try rebooting your computer? Because the mex setup should recognize the supported compiler. I don't have a mac, so I can't do any testing for you.

[Wang Yankai]

no, it still doesn't work. If there is anything wrong because I ran the code 'ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null' in my Terminal?

[Wang Yankai]

Ok, finally, I updated Matlab to 2018a, then it worked. Thank you!:)