Memory alignment fix for VS2013 x64

[rafalbigaj]

On Windows x64 compilation with VisualStudio 2013 any call to ffi function ends with segmentation fault.
It's caused by invalid memory alignment. The used mask 0x7UL is 32 bit on this platform, 0x7ULL is required.

[tduehr]

I'd like to do some testing of this. How do you have visual studio and ruby setup to compile gems rather than mingw?

[rafalbigaj]

You need to use VS2013 x64 Native Tools Command Prompt to build ruby and the ffi gem extensions.
I share the required ruby dependencies here: https://dl.dropboxusercontent.com/u/51529271/ruby-vc2013-x64-dep.zip.
Regular ruby compilation is required.
When building ffi gem extension I encountered problems when building ffi lib. I had to change manually warnings level -W3 to -W2 in Makefile.vc64 to ignore "non-fatal error".

[tduehr]

Thanks

Regular as in compile from source not the installer?

[rafalbigaj]

Yes, you have to compile ruby with Visual Studio.

[cfis]

Any chance this can be applied? I have just run into the same issue, and the patch correctly fixes it.