When compiling the juce core in a 64bit project with VisualStudio 2013 (admittedly not boilerplated with rejucer though), I get a static assertion failure from juce_String.cpp at this line:
static_jassert (sizeof (EmptyString) == sizeof (StringHolder));
I believe the problem has to do with the alignment specifier in the Atomic<int> (which is used in StringHolder, but not EmptyString):
#if JUCE_64BIT JUCE_ALIGN(8) #else JUCE_ALIGN (4) #endif
I did specify the JUCE_64BIT specifier: that makes no difference.
Taking the alignment macros out entirely makes it compile, but I don't know what consequences that has.
I used the master branch and the version Jule's committed to last evening - the code in question is there for a year now though, I don't think this is a new issue.
Maybe there's some additional build options I didn't set?