Fix warning, read/write have unsigned int count on windows.

2 files changed, 9 insertions, 2 deletions

diff --git a/src/nvim/macros.h b/src/nvim/macros.h
index 351fa55929..05065499f4 100644
--- a/src/nvim/macros.h
+++ b/src/nvim/macros.h
@@ -195,4 +195,11 @@
 # define UV_BUF_LEN(x)  (x)
 #endif
 
+// Type of bufcnt for read/write on Windows is unsigned int, not size_t.
+#if defined(WIN32)
+# define IO_SIZE(x)  (unsigned)(x)
+#else
+# define IO_SIZE(x)  (x)
+#endif
+
 #endif  // NVIM_MACROS_H
diff --git a/src/nvim/os/fs.c b/src/nvim/os/fs.c
index 5f29a45263..f3b3871aac 100644
--- a/src/nvim/os/fs.c
+++ b/src/nvim/os/fs.c
@@ -461,7 +461,7 @@ ptrdiff_t os_read(const int fd, bool *ret_eof, char *const ret_buf,
   while (read_bytes != size) {
     assert(size >= read_bytes);
     const ptrdiff_t cur_read_bytes = read(fd, ret_buf + read_bytes,
-                                          size - read_bytes);
+                                          IO_SIZE(size - read_bytes));
     if (cur_read_bytes > 0) {
       read_bytes += (size_t)cur_read_bytes;
     }
@@ -564,7 +564,7 @@ ptrdiff_t os_write(const int fd, const char *const buf, const size_t size)
   while (written_bytes != size) {
     assert(size >= written_bytes);
     const ptrdiff_t cur_written_bytes = write(fd, buf + written_bytes,
-                                              size - written_bytes);
+                                              IO_SIZE(size - written_bytes));
     if (cur_written_bytes > 0) {
       written_bytes += (size_t)cur_written_bytes;
     }