From 12b0e40ee4556318e5a0da3155f28bdfd7c5bc35 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlo=20Marcelo=20Arenas=20Bel=C3=B3n?= <carenas@gmail.com>
Date: Sun, 15 Jan 2023 14:38:44 -0800
Subject: [PATCH] build: make the C99 requirement explicit

Recent code uses C99 syntax (as reported in #163, and therefore it
will fail to build unless C99 (or higher) support is required by the
compiler (gcc >= 5 does it by default).

For those unfortunate to need an older compiler that does require a
flag to enable that, make sure that both autoconf and cmake make it
explicit.

While testing the change with the ancient autoconf version listed as
a prerequisite, noticed that the LT_INIT syntax introduced with 91485e5
(Update configure.ac for latest version of autoconf., 2021-02-02), was
not supported, so update the autoconf minimum as well.
---

diff --git a/CMakeLists.txt b/CMakeLists.txt
index cec7dfb4..a8147575 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -107,1 +107,3 @@
 PROJECT(PCRE2 C)
+set(CMAKE_C_STANDARD 99)
+set(CMAKE_C_STANDARD_REQUIRED TRUE)
 
 # Set policy CMP0026 to avoid warnings for the use of LOCATION in
 # GET_TARGET_PROPERTY. This should no longer be required.
diff --git a/configure.ac b/configure.ac
index ce5bda3c..67b2fdce 100644
--- a/configure.ac
+++ b/configure.ac
@@ -22,7 +22,7 @@ m4_define(libpcre2_posix_version, [3:4:0])
 # NOTE: The CMakeLists.txt file searches for the above variables in the first
 # 50 lines of this file. Please update that if the variables above are moved.
 
-AC_PREREQ([2.60])
+AC_PREREQ([2.62])
 AC_INIT([PCRE2],pcre2_major.pcre2_minor[]pcre2_prerelease,[],[pcre2])
 AC_CONFIG_SRCDIR([src/pcre2.h.in])
 AM_INIT_AUTOMAKE([dist-bzip2 dist-zip])
@@ -42,7 +42,7 @@ AC_CONFIG_MACRO_DIR([m4])
 
 remember_set_CFLAGS="$CFLAGS"
 
-AC_PROG_CC
+m4_version_prereq(2.70, [AC_PROG_CC], [AC_PROG_CC_C99])
 AM_PROG_CC_C_O
 AC_USE_SYSTEM_EXTENSIONS