As the 31 release seems to be delayed and there is no information on when it is due to be released I've been trying to build SpiderMonkey 24. I've managed to build it on Linux using gcc without any problems but I can't make any progress on windows at all. configure seems to be failing for me before I even get to the make stage.
I then run C:\mozilla-build\start-shell-msvcvs2013.bat
change directory to mozjs-24.2.0/js/src and run
This fails pretty quickly trying to build virtualenv which from what I've managed to work out is some sort of python build environment.
I get errors:
checking for python2.7... /c/mozilla-build/python/python2.7
Creating Python environment
New python executable in c:/SOURCE13/mozjs-24.2.0/js/src/_virtualenv\Scripts\python2.7.exe
Also creating executable in c:/SOURCE13/mozjs-24.2.0/js/src/_virtualenv\Scripts\python.exe