Building on Windows with mingw_64

[jlmelville]

I tried building this (immensely helpful and educational) package on Windows 10 with RStudio via devtools::load_all(".") and building with the g++ that comes with Rtools\mingw_64 fails. It doesn't realize it's on Windows, and wants to #include <sys/mman.h>.

Both the 32-bit and 64-bit versions of MinGW have a __MINGW32__ macro, so changing the check on line 37 of annoylib.h worked for me:

#if defined(_MSC_VER) || defined(__MINGW32__)
#ifdef _MSC_VER
#define NOMINMAX
#endif
#include "mman.h"
#include <windows.h>
#else
#include <sys/mman.h>
#endif

[eddelbuettel]

Hm, but it build fine on Windows as it does everywhere else.

Plus, that is a line in the upstream code.

[eddelbuettel]

And it is still unchanged upstream so it seems like you should make sure load_all() does not unset _MSER_VER which it may. Not our fault.

Also, try to communicate with diff output, not new code chunk as that makes the change more apparent.