From 5e7f0357fb44849e551bfbe5077bd56fef9e2475 Mon Sep 17 00:00:00 2001
From: Albrecht Schlosser <albrechts.fltk@online.de>
Date: Tue, 15 Jul 2025 18:50:42 +0200
Subject: [PATCH] Fix compiler warning [-Wundef]

warning: "_WIN32" is not defined, evaluates to 0 [-Wundef]

Manually backported from master (FLTK 1.5):
commit 2d2f474794f46fae6d12b97661d4bebe5bb21085
---
 fluid/fluid.cxx | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fluid/fluid.cxx b/fluid/fluid.cxx
index c8b2292d1..6e3f1fb15 100644
--- a/fluid/fluid.cxx
+++ b/fluid/fluid.cxx
@@ -1,7 +1,7 @@
 //
 // FLUID main entry for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2024 by Bill Spitzak and others.
+// Copyright 1998-2025 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -285,7 +285,7 @@ static void create_tmpdir() {
   tmpdir_create_called = true;
 
   char buf[128];
-#if _WIN32
+#ifdef _WIN32
   // The usual temp file locations on Windows are
   //    %system%\Windows\Temp
   //    %userprofiles%\AppData\Local