From 1bdbf55cbf054bd2a4d0cd57b0a162522ce33a60 Mon Sep 17 00:00:00 2001
From: Jakob Kaivo <jkk@ung.org>
Date: Thu, 13 Aug 2020 10:21:41 -0400
Subject: cause an error if _POSIX_C_SOURCE >= 200112L or _XOPEN_SOURCE >= 600
 is defined without a C99 or better compiler

---
 ftw.h | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'ftw.h')

diff --git a/ftw.h b/ftw.h
index 219a486..4b6c922 100644
--- a/ftw.h
+++ b/ftw.h
@@ -48,6 +48,14 @@ SOFTWARE.
 #	define _POSIX_SOURCE
 #endif
 
+#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 19901L
+#	if (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 200112L)
+#		error POSIX.1-2001 and later require a C99 compiler
+#	elif (defined _XOPEN_SOURCE && _XOPEN_SOURCE >= 600)
+#		error XOPEN Issue 6 and later require a C99 compiler
+#	endif
+#endif
+
 #if	(defined _XOPEN_SOURCE)
 /* ./src/ftw/FTW_D.c */
 #define FTW_D                                                             (1<<1)
-- 
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