From 912a8dcfc5369d840dcd6bf0f88ee0bac7d902d6 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Thu, 30 Sep 2021 18:24:37 +0900
Subject: [PATCH] Needs `AC_PROG_CC`

Although `AC_PROG_CC_C99` has been obsolete, `AC_PROG_CC` is not
and the latter is necessary not to make C++ compiler mandatory.
---
 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index b24a8f59b0..c7059ee1ec 100644
--- a/configure.ac
+++ b/configure.ac
@@ -203,7 +203,7 @@ rb_test_CXXFLAGS=${CXXFLAGS+yes}
 # BSD's ports and MacPorts prefix GNU binutils with 'g'
 
 dnl Seems necessarily in order to add -std=gnu99 option for gcc 4.9.
-m4_version_prereq([2.70], [], [AC_PROG_CC_C99])
+m4_version_prereq([2.70], [AC_PROG_CC], [AC_PROG_CC_C99])
 
 AC_PROG_CXX
 AC_PROG_CPP
-- 
2.31.1