Error using mex 'No supported compiler was found' on Mac.

I am trying to run a c++ program in Matlab. To do this I am using mex. I have a mac.

I was trying to get my c++ files to run but that wasn't working so to begin with I have been trying to use this example provided by MATLAB: https://uk.mathworks.com/help/matlab/matlab_external/build-an-executable-mex-file.html

Each time I run the command 'mex timestwo.c' I recieve the same error as when I was trying to get my own programme to run. The error says:

'Warning: Xcode is installed, but its license has not been accepted. Run Xcode and accept its license agreement.

Error using mex

No supported compiler was found. For options, visit https://www.mathworks.com/support/compilers.'

This seems to be a very common problem and I have looked through all the guidance I can find but I am still recieving the same error. I have xcode 10.x and MATLAB 2019a and I have accepted the Xcode licence.

Thank you in advance

[Jan]

Matlab needs a installed compiler for the compilations. Did you install XCode? If so, which version? What is the output of:

mex -setup

?

[Hannah West]

Thanks Jan for the quick response. I am using Xcode Version 10.2.1 (10E1001). The output of 'mex -setup' is the same error I was receiving before.

'Warning: Xcode is installed, but its license has not been accepted. Run Xcode and accept its license agreement.

Error using mex

No supported compiler was found. For options, visit https://www.mathworks.com/support/compilers.'

But I have installed xcode and I have accepted the license.

Thanks

Hannah

Answer 1

[Jan]

Posting the error message offers new insights. Did you try this already - in a command shell of the operating system:

sudo xcodebuild -license accept

The thread https://www.mathworks.com/matlabcentral/answers/435292-mac-matlab-2018b-with-xcode10-installed-still-no-supported-compiler-was-found seems to show, that this does not solve the problem in all cases.

[Hannah West]

Yes I have, and still no luck! And I also checked it was looking in the right place using

'sudo xcode-select -s /Applications/Xcode.app/Contents/Developer'

[fadams18]

did you find a solution? I have the same issue

[Koren Murphy]

I am also having the same issue - was the solution found?

[Richard DeFazio]

Combining these two worked for me. Typing Hannah's second comment:

sudo xcode-select -s /Applications/Xcode.app/Contents/Developer

followed by Jan's comment:

sudo xcodebuild -license accept

[Paul Serna-Torre]

After installing XCode from the App store, I ran the two lines that Richard typed. Then the accelerator and rapid accelerator are running now. I am using Matlab 2023b and my mac version is Ventura 13.5.1.

Answer 2

[Shams Rashid]

I want to post my experience in case anyone else has a similar issue. After updating to macOS Sonoma 14.4.1 from macOS 12.x (yes, not updating sooner is very bad practice!), I found that one of my previously compiled mex files was no longer working. It ran without errors, but the output produced was in the order of 1^10 and incorrect. I updated my Matlab version, then updated Xcode to the latest version, and the mex file would not compile. I then followed the instructions on this page. I ran the commands:

sudo xcode-select -s /Applications/Xcode.app/Contents/Developer

and then

sudo xcodebuild -license accept

after which the mex file compiled, but it still produced the incorrect output. I finally found a solution in this link:

https://www.mathworks.com/matlabcentral/answers/600481-compiling-mex-files-with-xcode-error-using-mex

I followed those instructions and replaced int * with mwIndex * in the C file, compiled it, and then it finally worked and produced the expected output! So I guess the problem had to do with going from a 32-bit system to a 64-bit system. Funny thing is that the 32-bit version of the mex file worked OK on macOS 12.

My computer is a 16-inch 2019 MacBook Pro, Intel processor.