From a712864e91584b24919c8d2aafa5a71503f7f978 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kornel=20Lesin=CC=81ski?= <kornel@geekhood.net>
Date: Tue, 21 Jul 2020 20:07:51 +0100
Subject: [PATCH] Avoid redefinition when vars are duplicated

---
 sys/build.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/build.rs b/sys/build.rs
index 924ed29f..cf2ebfb4 100644
--- a/sys/build.rs
+++ b/sys/build.rs
@@ -348,12 +348,14 @@ fn check_features(
         }
         includes_code.push_str(&format!(
             r#"
+            #ifndef {var}_is_defined
             #ifndef {var}
             #define {var} 0
             #define {var}_is_defined 0
             #else
             #define {var}_is_defined 1
             #endif
+            #endif
         "#,
             var = var
         ));