From 6aabf42189a814aded49ac4b71e8ad6823caf705 Mon Sep 17 00:00:00 2001
From: Peter Kokot <peterkokot@gmail.com>
Date: Thu, 19 Jan 2023 23:31:25 +0100
Subject: [PATCH] AC_PROG_CC_C99 is obsolete with autoconf >= 2.70

To make sure that compiler supports C99 before Autoconf 2.69, this was
needed. But with Autoconf 2.70 and later the macro is obsolete because
the checks are done in AC_PROG_CC and warnings are emitted when building
configure script.
---
 configure.ac | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 690b6ad0a26e4..b0697e3208db0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -128,7 +128,9 @@ PKG_PROG_PKG_CONFIG
 AC_PROG_CC([cc gcc])
 PHP_DETECT_ICC
 PHP_DETECT_SUNCC
-AC_PROG_CC_C99
+
+dnl AC_PROG_CC_C99 is obsolete with autoconf >= 2.70 yet necessary for <= 2.69.
+m4_version_prereq([2.70],,[AC_PROG_CC_C99])
 AC_PROG_CPP
 AC_USE_SYSTEM_EXTENSIONS
 AC_PROG_LN_S