I actually prefer x64 VC++'s inline asm support to the gcc variety. C99 support has been OK since VS2012 in my experience. Library support was iffy in earlier

I actually prefer x64 VC++'s inline asm support to the gcc variety. C99 support has been OK since VS2012 in my experience. Library support was iffy in earlier versions, but anybody accustomed to actually writing multi-platform code could handle it. A bit of a silly situation, but, as always, if you need to target multiple systems, you just do what you have to. Luckily, you can now probably rely on VS2015 or better.