Compiler not found when upgrading to Xcode 7

>> mex cpp/helloworld.cpp
Error using mex
No supported compiler or SDK was found. For options, visit 
http://www.mathworks.com/support/compilers/R2014a/maci64.

>> mex cpp/helloworld.cpp -v
Verbose mode is on.
Neither -compatibleArrayDims nor -largeArrayDims is selected.
   Using -compatibleArrayDims. In the future, MATLAB will require the use of
   -largeArrayDims and remove the -compatibleArrayDims option.
   For more information:
   http://www.mathworks.com/help/matlab/matlab_external/upgrading-mex-files-to-use-64-bit-api.html.
... Looking for compiler 'Xcode Clang++' ...
... Executing command 'xcode-select -print-path' ...Yes ('/Applications/Xcode.app/Contents/Developer').
... Looking for folder '/Applications/Xcode.app/Contents/Developer' ...Yes.
... Executing command 'which xcrun' ...Yes ('/usr/bin/xcrun').
... Looking for folder '/usr/bin' ...Yes.
... Executing command 'defaults read com.apple.dt.Xcode IDEXcodeVersionForAgreedToGMLicense' ...Yes ('4.5.2').
... Executing command '
agreed=4.5.2 
 if echo $agreed | grep -E '[\.\"]' >/dev/null; then 
 lhs=`expr "$agreed" : '\([0-9]*\)[\.].*'` 
  rhs=`expr "$agreed" : '[0-9]*[\.]\(.*\)$'` 
 if echo $rhs | grep -E '[\."]' >/dev/null; then 
 rhs=`expr "$rhs" : '\([0-9]*\)[\.].*'` 
 fi 
 if [ $lhs -gt 4 ] || ( [ $lhs -eq 4 ] && [ $rhs -ge 3 ] ); then 
 echo $agreed 
 else 
 exit 1
 fi 
 fi' ...Yes ('4.5.2').
... Executing command 'xcode-select -print-path' ...Yes ('/Applications/Xcode.app/Contents/Developer').
... Looking for folder '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk' ...No.
... Looking for folder '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk' ...No.
... Looking for folder '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk' ...No.
... Executing command 'find /Applications/Xcode.app/Contents/Developer -name MacOSX10.7.sdk' ...No.
... Executing command 'find $$ -name MacOSX10.8.sdk' ...No.
... Executing command 'find $$ -name MacOSX10.9.sdk' ...No.
Did not find installed compiler 'Xcode Clang++'.
Error using mex
No supported compiler or SDK was found. For options, visit 
http://www.mathworks.com/support/compilers/R2014a/maci64.

Answer 1

[Walter Roberson]

http://uk.mathworks.com/matlabcentral/answers/243868-mex-can-t-find-compiler-after-xcode-7-update-r2015b

Please be sure to read all of the comments as some additional changes are noted there.