The Handmade Hero code triggers a lot of warnings (primarily variable shadowing) in VS2015. These can be supressed with the flag -Wv:18.
Maybe Casey could add this, so VS2015 users don't have to do this every time.
VS2015 also is not happy about implicitly casting from double to float in line 40 of handmade_intrinsics.h.
Maybe use fabsf instead of fabs?