From d18170da1436d0cd52aa641d80ae44827dba28f1 Mon Sep 17 00:00:00 2001
From: Thomas Beutlich <modelica@tbeu.de>
Date: Fri, 9 Apr 2021 20:02:31 +0200
Subject: [PATCH] Fix C89 compliance

---
 Modelica/Resources/C-Sources/ModelicaInternal.c | 4 ++++
 Modelica/Resources/C-Sources/snprintf.c         | 2 +-
 Modelica/Resources/C-Sources/zlib/gzguts.h      | 3 +++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/Modelica/Resources/C-Sources/ModelicaInternal.c b/Modelica/Resources/C-Sources/ModelicaInternal.c
index 99066486aa..2dbec6a4d3 100644
--- a/Modelica/Resources/C-Sources/ModelicaInternal.c
+++ b/Modelica/Resources/C-Sources/ModelicaInternal.c
@@ -132,6 +132,10 @@
                      ModelicaInternal_getFullPath
 */
 
+#if defined(__gnu_linux__) && !defined(NO_FILE_SYSTEM)
+#define _GNU_SOURCE 1
+#endif
+
 #include "ModelicaInternal.h"
 #include "ModelicaUtilities.h"
 
diff --git a/Modelica/Resources/C-Sources/snprintf.c b/Modelica/Resources/C-Sources/snprintf.c
index 62ed611c07..b216522342 100644
--- a/Modelica/Resources/C-Sources/snprintf.c
+++ b/Modelica/Resources/C-Sources/snprintf.c
@@ -522,7 +522,7 @@ static UINTMAX_T cast(LDOUBLE);
 static UINTMAX_T myround(LDOUBLE);
 static LDOUBLE mypow10(int);
 
-//extern int errno;
+/*extern int errno;*/
 
 int
 rpl_vsnprintf(char *str, size_t size, const char *format, va_list args)
diff --git a/Modelica/Resources/C-Sources/zlib/gzguts.h b/Modelica/Resources/C-Sources/zlib/gzguts.h
index 990a4d2514..01a2d5e01c 100644
--- a/Modelica/Resources/C-Sources/zlib/gzguts.h
+++ b/Modelica/Resources/C-Sources/zlib/gzguts.h
@@ -101,6 +101,9 @@
 #  ifdef __MVS__
 #    define NO_vsnprintf
 #  endif
+#  ifndef STDC99
+#    define NO_vsnprintf
+#  endif
 #endif
 
 /* unlike snprintf (which is required in C99), _snprintf does not guarantee