From 5cf15a9b11cfdfaaa58698708cd1d222efc00226 Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Fri, 25 Mar 2022 21:37:39 +0100
Subject: [PATCH] Try to work around the issue with <compare>.

---
 lib/globals.h | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/globals.h b/lib/globals.h
index 580ab03d..576dc9aa 100644
--- a/lib/globals.h
+++ b/lib/globals.h
@@ -1,6 +1,20 @@
 #ifndef GLOBALS_H
 #define GLOBALS_H
 
+#if defined(_MSVC_LANG)
+    #define CPP_VERSION _MSVC_LANG
+#else
+    #define CPP_VERSION __cplusplus
+#endif
+
+#define CPP20_PRESENT (CPP_VERSION >= 202002L)
+
+#if defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_three_way_comparison)
+    #define CPP20_COMPARISONS_PRESENT ((__cpp_impl_three_way_comparison >= 201907L) && (__cpp_lib_three_way_comparison >= 201907L))
+#else
+    #define CPP20_COMPARISONS_PRESENT CPP20_PRESENT
+#endif
+
 #include <stddef.h>
 #include <functional>
 #include <numeric>
@@ -15,7 +29,10 @@
 #include <climits>
 #include <variant>
 #include <optional>
-#include <compare>
+
+#if defined CPP20_COMPARISONS_PRESENT
+    #include <compare>
+#endif
 
 #if defined(_WIN32) || defined(__WIN32__)
 #include <direct.h>