From bde60daa0ec9d0ee8dc79c0caa2c94d128527867 Mon Sep 17 00:00:00 2001
From: Thomas Munro <tmunro@postgresql.org>
Date: Wed, 20 Jul 2022 16:09:50 +1200
Subject: [PATCH] Fix warnings on Windows.

Avoid macro redefinition warnings.

Reported-by: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/CAApHDvocHp4SXcPeMTwFiCQGaf9JypjTJ3Bh90jcPuGwxyDjjQ%40mail.gmail.com
---
 src/include/port/win32_port.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 5ea66528fa..4de5bf3bf6 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -87,7 +87,9 @@
  * We have a replacement for fdatasync() in src/port/fdatasync.c, which is
  * unconditionally used by MSVC and Mingw builds.
  */
+#ifndef HAVE_FDATASYNC
 #define HAVE_FDATASYNC
+#endif
 
 #define USES_WINSOCK