patch 8.0.0840: MS-Windows: fopen() and open() prototypes are wrong commit https://github.com/vim/vim/commit/b6843a007da9c06bd8f9491cc12e5e0afd858f33 Author: Bram Moolenaar <Bram@vim.org> Date: Wed Aug 2 22:07:12 2017 +0200 patch 8.0.0840: MS-Windows: fopen() and open() prototypes are wrong Problem: MS-Windows: fopen() and open() prototypes do not match the ones in the system header file. Can't build without FEAT_MBYTE. Solution: Add "const". Move macro to after including protoo.h.

--- a/src/vim.h
+++ b/src/vim.h
@@ -2141,6 +2141,11 @@ typedef enum {
 # define number_width(x) 7
 #endif
 
+/* This must come after including proto.h */
+#if !(defined(FEAT_MBYTE) && defined(WIN3264))
+# define mch_open(n, m, p)	open((n), (m), (p))
+# define mch_fopen(n, p)	fopen((n), (p))
+#endif
 
 #include "globals.h"	    /* global variables and messages */