xcrun: error: unable to find utility "clang"

While building the ParaMonte MATLAB library on macOS, you may receive a compiler error message similar to the following,

xcrun: error: unable to find utility "clang", not a developer tool or in PATH

or particularly, after macOS automatic update to a more recent version, for example, macosx10.15.4,

MEX - xcodebuild: error: SDK "macosx10.15.4" cannot be located

To resolve this error,

• Open MATLAB. On the MATLAB command line, type,

  compilerCfg = mex.getCompilerConfigurations
  open(compilerCfg(1).MexOpt)
  open(compilerCfg(2).MexOpt)
  

• The above commands should open two MATLAB internal files named mex_C_maci64.xml and mex_C++_maci64.xml. Toward the ends of each one of these files, look for a line that is similar to, or exactly, the following,

  <SDKVER>
      <cmdReturns name="xcrun -sdk macosx --show-sdk-version"/>
  </SDKVER>
  

• Once you find the lines, replace them with the following,

  <SDKVER>
      <cmdReturns name="xcrun -sdk macosx --show-sdk-version | cut -c1-5"/>
  </SDKVER>
  

  Once you make the changes, save boths files and close them.

• Now, on the MATLAB command line, type,

  mex -setup C++
  mex -setup C
  

• The above should hopefully fix the error. Now open a Bash terminal and rerun the same command that you originally used to build the ParaMonte library.